Single-layered high-efficiency catalyst for treating exhaust gases of internal combustion engine and a method for preparing the same
FIELD: gas treatment catalysts.
SUBSTANCE: invention provides catalyst consisted of inert carrier and catalytic coating containing platinum, rhodium, and oxide substrate, wherein catalytic coating includes: (i) at least one first substrate material selected from group consisted of first active aluminum oxide enriched with cerium oxide; mixed oxide, which is cerium oxide/zirconium dioxide; and zirconium dioxide component; provided that catalytic component in at least one first substrate material is first portion of the total quantity of catalyst platinum, wherein concentration of the first portion of the total quantity of catalyst platinum lies within a range of 0.01 to 5.0% of the total mass of catalyst-containing materials; and (ii) a second substrate material containing second portion of total quantity of platinum and rhodium as catalytic component, said second substrate material being second active aluminum oxide, wherein concentration of platinum plus rhodium on the second substrate material lies within a range of 0.5 to 20% of the total mass of the second substrate material. Method for preparing above catalyst is also provided.
EFFECT: increased catalytic activity and reduced catalyst preparation expenses.
17 cl, 3 dwg, 5 tbl, 3 ex
The present invention relates to a single layer of highly efficient three-component catalytic Converter (TAC), comprising an inert carrier-based catalytic coating containing platinum, rhodium and various oxide materials.
Three-way catalytic converters are used to convert those contained in the exhaust gases of internal combustion engines of toxic constituents as carbon monoxide (CO), hydrocarbons (HC) and oxides of nitrogen (NOx), into harmless substances. In the known three-component catalytic converters with good activity and durability by using one or more catalytic components of the platinum group metals such as platinum, palladium, rhodium deposited on a refractory oxide carrier with a large specific surface area, such as aluminum oxide with a large specific surface area. The basis is usually in the form of a thin layer or coating on acceptable carrier or substrate, such as a monolithic carrier comprising a refractory ceramic or metal honeycomb structure.
Growing demand for high catalytic activity and durability has led to the creation of complex catalytic forms, including many catalytic layers on the structures of the carrier, being the m each of these layers includes selected materials fundamentals and catalytic components, as well as so-called promoters, stabilizers and accumulate oxygen connection.
For the application of different layers on patterns of media prepare so-called dispersion for coating compositions for coatings or compositions based on γ-aluminium oxide, which include substrate materials in finely ground form and optional additional soluble components. The preferred liquid phase composition for coating is water. This composition for coating use for drawing on patterns of native catalytic coating. Technology coating specialist in this field of technology is well known. Next a fresh coating is dried and calicivirus to secure the cover and for the conversion of the optional soluble components of compositions for coatings in their final insoluble form.
In the preparation of catalytic converters with dual layer or multilayer catalysts for each layer need to be prepared intended for him composition for coatings. This increases the cost of the retrieval process. Thus, the aim of the present invention is to provide a single layer of catalyst on the catalytic properties of approaching difficult to prepare multilayer catalytic converters.
In modern tricomponent the x catalytic converters use platinum group metals: platinum, palladium and rhodium. Platinum and palladium contribute mainly to the oxidation of hydrocarbons (HC) and carbon monoxide (CO) and may be present in the catalytic Converter simultaneously or alternately. Rhodium contributes mainly to the recovery of oxides of nitrogen (NOx). While platinum and palladium may to some extent each other to replace the rhodium is not suitable. Requirements for efficient purification of the exhaust gases is promoted by most modern legal standards can be met at acceptable costs only with the use of rhodium plated together with platinum or palladium or both of them.
On the other hand, noted that radiogardase three-way catalytic converters are subject to the so-called aging at the termination of the fuel supply. The concept of "aging in the termination of fuel supply" reflects the deterioration in the performance of catalytic converters due to the termination of the fuel supply after operation of the internal combustion engine at high load. This situation often occurs during periods of fast driving car when you need emergency deceleration. During high-speed driving, the engine operates at such ratios of air/fuel, which is slightly below the stoichiometric mn of the treatment. Exhaust gas temperature can reach values that are much higher than 900°that is the reason for the higher temperature catalytic Converter due to exothermic reactions of turning on the catalyst. In the event of a sharp slowdown modern electronic controls operation of the engine completely stop fuel flow to the engine, resulting in the value of the normalized ratio of the air/fuel (also called the coefficient of excess air λ) in exhaust gases is changing dramatically with the rich to the poor.
Such a large amplitude changes of the values of the normalized ratio of the air/fuel from the rich to the poor at high temperatures the catalytic Converter reduces the catalytic activity. Catalytic activity can at least partially restore long-term operation of the engine under conditions of stoichiometric or rich ratio in the exhaust gases. The faster return catalytic activity after aging due to the termination of fuel supply, the higher the efficiency of the catalytic Converter as a whole. Thus, accelerate the recovery of catalytic activity after aging due to the termination of fuel flow to the modern three-component catalytic is such converters is required.
Therefore, another objective of the present invention is to provide a catalyst with high resistance against aging by stopping the fuel supply. In other words, after high-temperature aging in poor exhaust gases such catalyst must quickly fully restore its effectiveness in relation to the transformation of the three main present in the exhaust gases components. The reduction of the degree of aging at the termination of the fuel supply will, apparently, to improve the overall dynamic behavior of the catalytic Converter.
In the US 4965243 described single-layer three-component catalyst comprising activated alumina, platinum and rhodium in a weight ratio of 5:1, and optionally cerium oxide, barium oxide and zirconium dioxide. This combination of components is said to be very effective for maintaining excellent catalytic activity even after exposure to the catalyst to high temperatures (900-1100°).
In the US 5200384 described single-layer three-component catalyst comprising activated alumina, platinum and rhodium in a weight ratio of 5:1, and optionally cerium oxide, aoademy with Zirconia stabilized with cerium oxide, in which the mass ratio of cerium oxide and zirconium dioxide is the limit is x 1:99-25:75. Adding soosazhdenie Zirconia stabilized with cerium oxide, ternary catalyst increases, as stated, the catalyst activity at low temperature after high temperature aging.
In the US 5254519 described single-layer catalyst, comprising a combination of the obtained rare earth element oxide from zirconium dioxide, containing dispersed therein rhodium component and a first activated alumina containing dispersed thereon a platinum component. This catalyst may include a second rhodium component dispersed on the first aluminiumoxide basis. According to another variant of the second rhodium component may be dispersed on the second aluminiumoxide component.
In recent years one could observe the trend for a complete replacement triple platinum in the catalyst palladium due to its lower price and good oxidation activity. Were created palladium/rhodium and platinum/palladium/rhodium three-component catalysts that at high palladium content exhibit excellent catalytic activity. Meanwhile, the high demand for palladium creates accumulation of palladium in the world, associated with a significant increase in palladium prices. Currently, palladium is more expensive is, than platinum. Thus, another object of the present invention is enabling the use of platinum and rhodium in the catalyst with less expensive at the price of metals, but at the catalytic activity equivalent to the activity of palladium - and registergui catalysts.
These and other objectives of the invention are achieved by creating a highly efficient single-layer catalyst comprising an inert carrier-based catalytic coating containing platinum, rhodium and various oxide materials.
The catalyst is characterized by the fact that the catalytic coating includes
a) at least one first material is a substrate selected from the group comprising the first active alumina rich in cerium oxide mixed oxide in the form of cerium oxide/zirconium dioxide and zirconocenes component, and at least one first material substrate as a catalytic component, enter the first part of the total amount of platinum in the catalyst, and
b) the second material is a substrate, in which as a catalytic component enter the second part of the total amount of platinum and rhodium, and the second material substrate is a second active alumina.
The concept of "containing catalytic component material" denotes a material on the surface is ti which in finely dispersed form contains a catalytically active components, such as platinum, rhodium and palladium.
The present invention is based on the entity described in conjunction considering the European patent application filed by the authors of the present invention, published under the number EP A2-1046423. In this proposal describes a two-layer catalyst with the inner and outer layers on an inert carrier basis, including noble metals of the platinum group deposited on materials and substrates. Platinum inner layer precipitated on the first substrate and the first oxygen-storing component, and platinum outer layer and rhodium precipitated on the second substrate, and the second layer further comprises a second accumulating oxygen component.
The catalyst for this jointly consider the European patent application shows excellent catalytic properties comparable to the properties of palladium - and registergui three-component catalysts. When creating the present invention attempts to achieve similar catalytic properties to develop a single layer of catalyst in order to reduce the cost of its preparation.
The preparation of the catalyst of the present invention reduced the degree of aging and improved dynamic behavior and catalytic activity reaches placement on designated material is x-substrates platinum and rhodium. The increased catalytic activity of such a catalyst can reduce the content of precious metals, while maintaining the catalytic activity comparable with the activity of a modern three-component palladium/rhodium catalysts. This leads to reducing the cost of precious metals in comparison with the cost of them in the usual catalysts.
The essential difference between the present invention is that the entire rhodium, on the catalyst, tightly associated with platinum. This is done by deposition of the second part of the total quantity of platinum and rhodium on the same powdery material substrate, the second active alumina.
In accordance with this aspect of the invention causes decreased sensitivity to aging at the termination of the fuel supply can be that large amplitude changes of the values of the normalized ratio of the air/fuel from the rich to the poor at high temperatures of the catalyst reduces the catalytic activity primarily rhodium. In terms of stoichiometric or rich exhaust gas rhodium is recovered to almost zero oxidation state, which for the catalysis of the conversion of the three components is the most effective condition. In poor exhaust gases and at high temperatures rolled atora rhodium is oxidized to the level of oxidation of +3. In this state of oxidation of rhodium is less active for the conversion of three toxic components. Moreover since in the crystallographic structure of Rh2About3is isomorphic to the relative Al2O3at temperatures exceeding 600°With, he is able to migrate into the crystal lattice of the aluminum oxide or isomorphic other oxide substrates of the General composition M2About3(M denotes a metal atom), resulting in catalytic activity is constantly decreasing.
Thus, to return to its catalytic activity and prevent loss of rhodium in the crystal lattice of the aluminum oxide when the composition of the exhaust gas changes, returning to the stoichiometric rhodium need as quickly as possible to restore. In accordance with this aspect of the invention, the recovery of rhodium to the zero-state oxidation catalyzed by platinum. The more dense is the contact between the platinum and rhodium, the greater this effect recovery.
In addition, the trend Rh2About3to migration is isomorphic to the oxide substrate can limit the appropriate doping of these oxides. The favorable influence of the alloying components in the reducing conditions capable of forming the activated hydrogen. In reducing the conditions activated hydrogen promotes more rapid translation of rhodium oxide in the metal mold and, therefore, to further minimize the risk of migration Rh2O3in the oxide basis. Suitable alloying component is cerium oxide (cerium oxide). But since the cerium oxide is also the ability to store and release oxygen, the amount of cerium oxide used in the doping should be small, as too high a content of cerium oxide in the oxide substrate promotiom oxidation of rhodium.
Further improve the stability of the catalyst against aging reach the appropriate choice is accumulating oxygen component. It is well known that cerium oxide exhibits the ability to store oxygen. In poor exhaust gas cerium fully oxidized to the oxidation state of CE4+. In terms of rich exhaust gas, the cerium oxide emit oxygen and enters the oxidation state of CE3+. According to the present invention as accumulating oxygen compounds instead of pure cerium oxide using such mixed oxide compounds as rich oxide, cerium oxide, cerium/zirconium dioxide. The concept of the cerium oxide denote material containing more than 50 wt.% cerium oxide. The preferred concentration of the cerium oxide comprises 60-90 wt.% in terms of the total weight of the mixed oxide. Such materialization with a specific surface area 20-200 m 2/g and exhibit good thermal stability in relation to surface area. It is known that these materials have a cubic crystal form, such as the CEO2as described in US 5712218. Further improvements can be achieved by stabilization of this material oxide, praseodymium, yttrium oxide, neodymium oxide, lanthanum oxide, gadolinium oxide or mixtures thereof. Stabilization accumulating oxygen materials based on cerium oxide using praseodymium oxide, neodymium oxide, lanthanum oxide or their mixtures described in DE A1-19714707. Stabilization of mixed oxides in the form of cerium oxide/Zirconia oxide praseodymium is much preferred.
As already mentioned, the second portion of the total quantity of platinum in the catalyst is in tight contact with the rhodium. This contributes to the recovery of rhodium oxide, formed during periods of stop the flow of fuel to a low state of oxidation. For this task the most effective mass ratio between platinum and rhodium is about 1:1. Nevertheless good enough catalytic activity is provided, as installed, in case of deviation from a ratio of 1:1 within 3:1-1:5. Although it is a mass ratio of platinum and rhodium, precipitated together on the second active alumina, effective, total wt the TV ratio of platinum/rhodium in the catalyst can be varied in the range of 10:1-1:5, preferably in the range of 10:1-1:1, and most preferably the ratio of 3:1.
Zirconocene component of the first materials-substrates can serve as zirconium dioxide, optionally stabilized with 0.5-10 wt.% yttrium oxide, cerium oxide, neodymium oxide, lanthanum oxide, praseodymium oxide, gadolinium oxide, or mixtures thereof. In another embodiment, zirconocenes component can inform the function of storage of oxygen by the addition of cerium oxide in a quantity sufficient to achieve a significant share of the total capacity of the catalyst to accumulate oxygen. The content of cerium oxide in such zirconocene component can be varied from above 1 to below 50 wt.% in terms of the total weight of zirconocene component. Such materials are technically available in the form of so-called mixed oxide type oxide zirconium/cerium oxide. In the name of "the dioxide of zirconium/cerium oxide" position "Zirconia" in the first place indicates that the zirconium dioxide is contained in a quantity at least equivalent, but usually exceeds the amount of cerium oxide. This zirconocenes component can additionally stabilize the above-mentioned stabilizers, namely yttrium oxide, neodymium oxide, lanthanum oxide, praseodymium oxide, gadolinium oxide or mixtures thereof, for the odd zirconium dioxide and cerium oxide. For example, the overall composition zirconocene component may include 99,5-45 wt.% zirconium dioxide and 0.5 to 55 wt.% cerium oxide, yttrium oxide, neodymium oxide, lanthanum oxide, praseodymium oxide, gadolinium oxide or their mixtures, resulting zirconium dioxide is contained in an amount which equals or exceeds the amount of cerium oxide.
The first material of the substrate constitute the bulk of the catalytic coating. The mass ratio between the first material, the substrate and the second material of the substrate is in the range from 1.1:1 to 20:1. The concentration of the first part of the total quantity of platinum catalyst on the first materials-substrates (selected from the active aluminum oxide, mixed oxides in the form of cerium oxide/zirconium dioxide and zirconocene component and mixtures thereof) is in the range of 0.01-5 wt.%, preferably 0.05 to 1 wt.%, in terms of the total mass containing catalysts materials. In contrast, the preferred concentration of platinum plus rhodium on the second material substrate (second active alumina) higher and is in the range of 0.5-20 wt.%, in terms of the mass of the second material of the substrate, and the preferred concentration is in the range of 1-15 wt.%. In General, platinum and rhodium held together in the catalytic coating in concentrations of 0.02-10 wt.% in terms of bwuu a lot of coverage.
Media-based catalyst used in the present invention, is in the form of honeycomb monolithic element with many passing through it almost parallel channels. These channels are defined by walls on which the catalytic coating is applied.
The channels in the carrier-based serve as passages for the movement of the exhaust gas flow of an internal combustion engine. When driving through these channels the exhaust gases come into tight contact with a catalytic coating, resulting in the toxic components contained in exhaust gases into harmless substances. Media-bases can be made from any acceptable material, in particular of metal or ceramic materials, as is well known in the art. The channels are in the form of a homogeneous structure throughout the cross section of the media-the basics. The so-called density of cells (number of channels per unit cross-sectional area) can vary in the range of 10-200 cm-2. Other acceptable media-the basics may have a structure poroplast with open pores. Can be used with metal or ceramic cellular plastics.
The catalytic coating is applied to the carrier-based in amounts from about 50 to 250 g/L. Preferable rolled the systematic coverage includes 0-150 g/l, preferably 20-150 g/l, the first active aluminium oxide and 10-100 g/l, preferably 20-100 g/l, mixed oxide component, a cerium oxide/zirconium dioxide. Zirconocenes component may contain concentrations 0-80 g/l, preferably 5-60 g/l
For proper operation of the catalyst is sufficient capacity to accumulate oxygen. The ability to store oxygen, the catalyst is reported primarily by rich cerium oxide component, a cerium oxide/zirconium dioxide. Some part of the overall ability of the catalyst to accumulate oxygen is also due to the small quantities zirconocene component. But in the preferred embodiment, the catalyst ability of the catalyst to accumulate oxygen caused only mixed oxide in the form of rich cerium oxide cerium oxide/zirconium dioxide, while zirconocenes component represents the net zirconocenes material or zirconium dioxide, stabilized with 0.5-10 wt.% the above-mentioned stabilizers.
The preferred concentration of the second active alumina is chosen in the range of 5-50 g/l In the most preferred embodiment, the first and second active alumina to use the same material with a specific surface area in the range of 50-200 m2/g, stabilizirovannyi 0.5 to 25 wt.% oxide of lanthanum, cerium oxide, yttrium oxide, neodymium oxide, gadolinium oxide, or mixtures thereof. Accumulating oxygen component it is advisable to choose from the rich cerium oxide mixed oxides of cerium oxide/zirconium dioxide, containing 60-90 wt.% cerium oxide and optionally stabilized with 0.5-10 wt.% oxide praseodymium (Pr6About11).
In order to suppress the hydrogen sulphide in the catalytic coating can also be entered from about 1 to 30 g/l Nickel, iron or manganese component.
Specific surface area materials-substrates for containing a noble metal component is important for the final catalytic activity the catalytic Converter. Typically, the specific surface area of these materials must be more than 10 m2/g Specific surface area of these materials in the art also referred to as surface area or specific surface area by BET. The preferred specific surface area of the material should exceed 50 m2/g, most preferably greater than 100 m2/, Usually the specific surface area of the active alumina is equal to 140 m2/, Accumulate oxygen components based on cerium oxide or mixed oxides in the form of cerium oxide/zirconium dioxide available from specific areas in the s surface, depending on the state of calcination, in which it's delivered, from 80 up to 200 m2/, in Addition, it is also the so-called cerionidae materials with low specific surface area: less than 10 m2/, Also normal zirconocene materials with a 100 m2/year
Below the present invention is illustrated with reference to figures 1-3.
Figure 1. Figure 1 visually displays the structure of the options for performing a single-layer catalyst comprising first and second oxides of aluminum, cerium oxide/zirconium dioxide and zirconium dioxide as materials-substrates.
Figure 2. Figure 2 visually displays the structure of the second variant implementation of the single-layer catalyst comprising only the second aluminum oxide, cerium oxide/zirconium dioxide and zirconium dioxide as materials-substrates.
Figure 3. Figure 3 schematically presents used when performing the present invention chart of aging at the termination of fuel flow.
Figure 1 in cross-section a first embodiment of a catalytic coating comprising both the first and second active aluminum oxide. This coating is precipitated on an inert carrier. Different materials of the substrate of the catalyst is symbolically depicted in the form of different geometric shapes. Platinum precipitated only on the first oxide aluminium is s (represented by a hexagon), on the cerium oxide/zirconium dioxide (represented by the ellipse) and Zirconia (represented by octagon). Platinum crystallites is symbolically depicted by small circles. Platinum and rhodium precipitated on the second aluminum oxide. Rhodium crystallites is symbolically depicted by small diamonds. This catalyst is platinum and rhodium are in tight contact with each other. For visual indication of this fact in figure 1 platinum and rhodium crystallites placed in pairs. Such pairwise accommodation used only for explanatory purposes and is not intended to restrict the scope of the invention. The actual relationship between platinum and rhodium depends on the method of obtaining, so it can vary from isolated platinum and rhodium crystallites on the same particle of aluminum oxide through an intermediate phase of close proximity of platinum and rhodium crystallites before the actual platinum-rhodium alloys.
In accordance with this aspect of the invention believe that the best results are achieved with the close proximity of platinum and rhodium crystallites and the actual platinum-rhodium alloys.
Although according to figure 1 as substrates for platinum and platinum/rhodium applied respectively to the first and second oxides of aluminum, it must be borne in mind that the first choice is aluminum oxide as a substrate for platinum is an optional component, which can be deleted as platinum deposited on curiosity/zirconocenes and zirconocenes components. This option is proposed according to the invention of the catalyst are presented in figure 2. According to figure 2 the catalytic layer of the first aluminiumoxide component does not contain.
The catalyst according to the present invention can be prepared in various ways. Some of them are described below.
For applying the catalytic coating in the channels of the catalyst carrier the carrier of the catalyst can be coated water composition for coatings, including certain powdered materials of the substrate with the catalyst. In the context of the present invention, the composition for coatings usually referred to as a dispersion for coating. Technology coating on the carrier of catalysts with the use of such compositions for coatings specialist in this field of technology is well known. Next, the coating is dried and calicivirus on the air. In a preferred embodiment, drying is carried out at elevated temperatures, up to 150°C. During calcination of the coating, the temperature should be 200-500°and a duration of 0.5-5 hours
Before preparation of a composition for coating as catalysts in the materials of the substrate must enter the appropriate precious metals. For in the edenia in the materials of the substrate as a catalyst of platinum only, you can use basic technology, such as the impregnation solution containing the compound, the precursor of platinum. You can use any connection-the platinum precursor, provided that the compound is soluble in the selected solvent and decompose during exposure to air at elevated temperatures. Examples of these platinum compounds are platinochloride acid, chloroplatinic ammonium hydrate platinum tetrachloride, dichlorocarbanilide platinum, dinitrogen platinum, platinum nitrate and the solubilized the amine hydroxide platinum. Preferred compounds precursor with a low content of chlorine or without him. Especially preferred solubilization the amine compounds of platinum such as hexahydroxy methylethanolamine(IV) [(MEA)2Pt(OH)6] and hexahydroxy ethanolamine(IV) [(EA)2Pt(OH)6]. It is known that these anionic complex platinum compounds form a finely dispersed precipitation of metallic platinum. After impregnation, the material of the substrate is dried at elevated temperature for thermal fixing them platinum calicivirus in air at temperatures in the range of 200-500°C. Then, in the preferred embodiment, the materials introduced thus the catalyst is dispersed in water to obtain a first dispersion.
In a preferred method, the introduction paragraph is tiny as a catalyst in the relevant materials of the substrate to impregnate the so-called injection impregnation. The method of impregnation injectionem described in DE-A-1 19714732 and DE-A-1 19714707. To this end, the material of the substrate is dispersed in water and then in the dispersion slowly Inuktitut a solution of the compound of the platinum precursor, preferably (EA)2Pt(OH)6. Thereby the pH value of the dispersion increases, shifting it in the basic range. Further regulation of the pH of the dispersion acetic acid platinum precipitated in powder materials. The deposition starts, when it starts to decrease the pH value of the dispersion. Typically, to complete the precipitation of the desired pH value less than 7. In the processes of injection box and deposition for rapid and uniform distribution of the injected solution in the whole volume of the dispersion it is continuously stirred. The implementation of this method provides a solid anchoring of the besieged platinum compounds on the material-carriers, allowing thermal hardening by drying and calcining, as mentioned above, become unnecessary. The dispersion prepared according to this method can directly be used as the above-mentioned first dispersion.
Then the impregnation of the substrate with an aqueous solution of soluble compounds, the precursors of platinum and rhodium, and drying and calcining this impregnated substrate to prepare the second active aluminum oxide carrying platinum and rhodium. Acceptable those connections precursor of platinum, which is already mentioned above. As compounds of rhodium precursor can effectively use examinermichael, trichloride rhodium, carbonylchloride rhodium, hydrate trichloride rhodium, rhodium nitrate or acetate of rhodium, but the preferred rhodium nitrate.
The second active alumina can be impregnated with compounds precursors of platinum and rhodium or sequentially in any order or simultaneously using a single common solution. Active aluminum oxide with put it this way catalysts are dried and calicivirus for fixing it platinum and rhodium. Then this material is again dispersed in water to obtain a second dispersion. Next, the first and second dispersion combined with the receipt of the finished composition for coating.
However, as indicated above, it is necessary to achieve a tight contact between the platinum and rhodium. It was found that by the above injection deposition on the material of substrate is best to first precipitate platinum, and then rhodium. With this purpose, the primary connection is the precursor of platinum, preferably solubilisation an amine, such hexahydroxy ethanolamine(IV), precipitated by the relevant regulation of the pH of the dispersion acetic acid in which the limits of 6-8. After deposition of the platinum substrate is not dried and calicivirus, and then directly from the solution acidic compounds, a predecessor of rhodium such as rhodium nitrate, precipitated rhodium.
If detail then this second variance with platinum and rhodium deposited on the active aluminum oxide is prepared by dispersing the active aluminum oxide in water and then injectionem aqueous solution solubilizing the amine compounds of the platinum precursor in the dispersion for coating. Solubilizing the amine compound, the precursor of platinum easily adsorbed on the active alumina. After that, in such a dispersion Inuktitut aqueous solution of acidic compounds of rhodium precursor, and then appropriately adjust the pH value of the dispersion to secure compounds of platinum and rhodium on the second active alumina. Further, this second dispersion is combined with the first dispersion, getting ready catalytic composition for coating.
The improved properties of the catalyst, provided in accordance with the invention is further illustrated by the following examples. In the preparation of all of the catalysts shown in the following examples, was used by cellular carriers, made of cordierite (10.16 cm diameter; length of 15.24 cm; density of cells 62 cm-2). the values of the concentration or content of different primer components are given relative to the volume of media in grams per liter (g/l).
The catalyst in accordance with the invention was obtained by applying the cell carrier catalytic coating, as set out below. The finished coating consisted of platinum and rhodium in a weight ratio of 5:1 when the total content of noble metal 1,41 g/l (40 g/ft3). The concentration of the oxide of the coating components from γ-alumina was 160 g/l In the future, this catalyst is designated as K1.
Preparing a first dispersion
In the solution of praseodymium acetate was administered rich in cerium accumulating oxygen component (70 wt.% cerium oxide, 30 wt.% Zirconia, specific surface area: 200 m2/g). Adjustable injection of ammonia and stirring for about 30 min praseodymium acetate besieged on the cerium oxide/zirconium dioxide. Then added a stabilized aluminum oxide (3 wt.% La2O3, 97 wt.% Al2About3, specific surface area: 140 m2/g) and bulk zirconium dioxide (specific surface area: 100 m2/g). Later in the sludge was injectible solution of platinum compounds [(EA)2Pt(OH)6] and the corresponding regulation of the pH of the dispersion with the aid of acetic acid on the cerium oxide/Zirconia and Zirconia besieged platinum.
Preparing a second dispersion
Water was dispersively stabilization of the new alumina (3 wt.% La 2About3, 97 wt.% Al2About3). Next was injectively not containing platinum chloride salt [(EA)2Pt(OH)6], which was easily adsorbiroval aluminum oxide. After that was injectively rhodium nitrate. Both catalytic component was fixed on aluminiumoxide substrate regulation of pH using acetic acid.
Both dispersions were combined with obtaining compositions for coatings. Dipping the carrier in the composition was coated, it was dried and was caliciviral in air at 500°C.
Below visually shows the placement of the various components of the catalyst relative to each other. Numbers indicate the concentration of the components of the coating in grams per liter of volume of the medium. The result of deposition of praseodymium to cerium oxide/zirconium oxide during the preparation of the first dispersion after calcination of the coating was the cerium oxide/zirconium dioxide stabilized with praseodymium oxide (CeO2/ZrO2/Pr6O11). The concentration of cerium oxide/zirconium dioxide in this material was accounted for 51.7 g/l, whereas the concentration of praseodymium oxide was equal to 4.3 g/L. the Composition of the catalyst is summarized in table 1.
In the first three rows represent the components of the coating applied using the first dispersion for coatings, and the fourth line presents the components received from the second dispersion.
Comparative example 1
The catalyst K1 in accordance with example 1 were compared with two-layer catalyst according to example 1 together consider European patent application published under number EP A2 1046423. The composition of this catalyst was identical to the composition of the catalyst of the present invention. He was different from the catalyst of the present invention that the substrate materials, including as a catalyst only platinum was in the first layer and the aluminum oxide, including as catalysts of platinum and rhodium, together with the other components were in the second, outer layer.
Preparation of the first (inner) layer
In the solution of praseodymium acetate was administered rich in cerium accumulating oxygen component (70 wt.% cerium oxide, 30 wt.% zirconium dioxide). Adjustable injection of ammonia and stirring for about 30 min praseodymium acetate besieged on the cerium oxide/zirconium dioxide. Then added a stabilized aluminum oxide (3 wt.% La2O3, 97 wt.% Al2O3and bulk Zirconia. Later in the sludge of V.N.Karazin Aravali solution of platinum compounds [(EA) 2Pt(OH)6] and the corresponding regulation of the pH of the dispersion using acetic acid, aluminum oxide, zirconium oxide and cerium oxide/Zirconia besieged platinum.
After grinding of the slurry in the slurry was dipped a monolithic carrier for the first layer. After drying and calcination in air at 500°With the total amount absorbed by the coating material from the γ-alumina was 160 g/l
Preparing a second dispersion
Water was dispersively stabilized aluminum oxide (4 wt.% La2About3, 96 wt.% Al2O3). Next was injectively not containing platinum chloride salt [(EA)2Pt(OH)6], which was easily adsorbiroval aluminum oxide. After that was injectively rhodium nitrate. Both catalytic component was fixed on aluminiumoxide substrate regulation of pH values.
At the end was administered composition for coating of the γ-aluminium oxide, aluminium oxide, praseodymium acetate and rich in cerium oxide accumulating oxygen component (70 wt.% cerium oxide, 30 wt.% zirconium dioxide).
Before applying on a monolithic substrate coating, the pH of the slurry is brought up to approximately 6, and crushed. The total amount absorbed by the coating material from the γ-alumina was 70 g/l, the Catalyst was dried and calcined what I in air at 500° C.
Below in table 2 visually displays the location and concentrations of the various components of the catalyst relative to each other.
In the first layer, the combination of a cerium oxide/zirconium dioxide stabilized with praseodymium oxide was characterized by the same mass ratio of cerium oxide/zirconium oxide and praseodymium oxide, as shown in example 1 (51,7/4,3). In the second layer of praseodymium acetate were soaked all the components of this layer.
The mass ratio between platinum and rhodium in the upper layer was 1Pt/1Rh. The total content of platinum and rhodium was equal to 1.41 g/l (1,175 g Pt/l and 0,235 g Rh/l) at a mass ratio 5Pt/1Rh (cumulative mass ratio for both layers). This comparative catalyst will be further denoted as W1.
Evaluation of catalysts
The catalysts in accordance with the invention and a comparative catalyst (both hereinafter referred to as "catalyst samples") were tested at operating temperatures in the vehicle with the internal combustion engine V8 (8 cylinder engine; engine: 5.3 l). The exhaust from this engine was equipped with two in series is placed converters of exhaust gases. The first transducer was directly connected to the engine, while the second transducer was located under the floor of the body.
Directly attached Converter was equipped with only palladium catalyst, the volume of which was 0,431 l when the diameter of 9.3 cm (3.66 inch) and the length of 6.35 cm (2.5 inches). The volume of sample catalysts was equal 0,776 l with the same diameter as the direct-attached catalyst, but their length was 11,43 cm (4.5 inches). Each of the two samples of the catalysts were placed in individual Converter under the floor of the body.
Before measuring the output temperature transducers with samples of catalysts designed for placement under the floor of the body, was first subjected to aging for 65 h at the test stand engines certified to EPA (environmental protection Agency environment) of the United States. The maximum temperature at the inlet to the Converter was equal to 850°C. This method of aging is widely considered the equivalent of riding a cycle of 80,000 km
Upon completion of the aging process both Converter, designed for placement under the floor of the body, one was installed on a test vehicle. Further in accordance with a test cycle FTP 75 ran the engine. Emissions collected in all three sets of data presented in table 3, the Emissions of carbon monoxide are not represented, because they remained significantly lower than all current and future emission limits.
The results of the test cycle FTP 75; package summary data for non-methane hydrocarbons (NAV) and oxides of nitrogen ( NOx)
Analogously to example 1 was prepared by another catalytic Converter. Unlike example 1, this catalyst was prepared in the mass ratio between the total amount of platinum and rhodium 2:1, while the mass ratio of platinum and rhodium on the second aluminum oxide was maintained at a level of 1:1. After drying and calcination, the concentration of the oxide components in the coating material prepared cell catalyst was 160 g/l, and platinum plus rhodium - 1.06 g/l (30 g/ft3). In the future, this catalyst is designated as K2.
Below visually shows the location and concentration values (in grams per liter of volume of media) of various catalyst components K2 relative to each other.
Comparative example 2
In the catalyst according to the invention is used, the active aluminum oxide stabilized with lanthanum oxide, powdered zirconium dioxide and powdered cerium oxide/zirconium dioxide as a substrate material for the noble metal catalyst.
The catalysts prepared according to the present state of this technology, often based on non-stabilized active alumina and powdered cerium oxide. In addition, the dispersion for coating additionally add cerium acetate and zirconium acetate and by calcining the catalytic coating is converted into a cerium oxide and zirconium dioxide, uniformly dispersed throughout the catalyst. Further impregnation compounds of platinum and rhodium in the floor impose catalytic component.
For comparison, the catalyst prepared according to this old technology, with a catalyst in accordance with the invention, a comparative catalyst W2 was prepared as follows. Water was dispersively active alumina (specific surface area of 140 m2/g) and powdered cerium oxide (material with low specific surface area, 10 m2/g). After the addition of cerium acetate and zirconium acetate formed dispersion for coatings used in the coating at the cell media. The obtained t is thus the substrate layer was dried and illnerova, and then simultaneously impregnated with platinum and rhodium with the application of the General solution of tetranitro platinum and rhodium nitrate. Soaked floor again dried and illnerova.
Below visually shows the location and concentrations of the various components of the catalyst W2 relative to each other.
Comparative example 3
Another comparative catalyst, designated as TC3, was prepared as follows. All oxide components of the catalyst of example 2, beginning as a catalytic component as in example 2 was introduced platinum, and then they were dispersible in the water and was coated on a honeycomb carrier. This coating was dried and was caliciviral. Next, the resulting catalytic layer was impregnated with rhodium nitrate, dried and illnerova. This comparative catalyst had the same total concentration of components as the catalyst K2. The only difference was the placement of platinum and rhodium on the materials of the substrate and relative to each other.
Below visually shows the location and concentrations of the various components of the catalyst TC3 relative to each other.
Comparative example 4
Another comparative catalyst, designated as SK4, prepared with the use of STRs is mandatory, already described in examples 1 and 2. Comparative catalyst SK4 had the same total concentration of components as the catalyst K2. Unlike example 2, platinum and rhodium were placed on different substrate materials, as it is visually shown below
Evaluation of catalysts K2, W2, TC3 and SK4
The aging process at the termination of fuel flow.
First, these four catalysts were subjected to the so-called aging at the termination of fuel flow to the engine with a displacement of 2.8 liters when the duration of 76 including the exhaust System, this engine was equipped with a special transitional details, which are allowed to be aging all four placed in parallel catalyst.
The aging process at the termination of the fuel supply included four cycles with a duration of 19 hours Each cycle consisted of two periods, as shown in figure 3. During period I, the catalysts were subjected to 75 podzilla processing, which simulated conditions at the termination of the fuel supply. During each subcycle corresponding increase of load on the engine the temperature of the exhaust gas before entering the catalyst regulating, supporting at level 850°C. the Engine is operated at a lambda value of 1 (the stoichiometric ratio). After the initial the stage of operation of the stoichiometric ratio for 360 with every 60 with 5 to interrupt the supply of fuel consequently, the lambda value is abruptly changed from 1 to 2.5. Due to the termination of fuel flow to the catalyst was affected by highly oxidizing conditions of the poor exhaust gases at high temperatures of exhaust gases. When working in the mode of the stoichiometric ratio due to exothermic reactions on the catalyst temperature of the catalyst was increased to 80-100°C. Each of the 75 potzilov continued 625 S.
Period II consisted of 12 potzilov that mimicked the poisoning of the catalysts by sulfur compounds at moderate temperatures of exhaust gases. During each subcycle the exhaust gas temperature was increased in three steps from 490 to 580°and then to 680°C. Each phase lasted for 10 minutes
After aging by stopping fuel supply to the engine with a working volume of 2 l was determined operating temperature T50%for the conversion of NA, CO, NOxand dynamic point of intersection of the CO/NOx. The term "operating temperature" means the temperature of the exhaust gas, when using the catalyst of the transformation are 50% of the toxic components of exhaust gases. For NS, and NOxthe working temperature can be different. The concept of "dynamic point of intersection" and its definition is described in detail in conjunction considering the European is what the patent application, submitted by authors of the present invention, the EP A2-1046423.
Determining the operating temperature was carried out at flow rate of 65,000 h-1with the gradual increase in the temperature of the exhaust gas (38 K/min) of the engine. During these definitions lambda is modulated with an amplitude of +0.5 V/T (a/T indicate the air/fuel) and a frequency of 1 Hz. The average lambda value regulated, maintaining a level 0,999.
The degree of conversion at the point of intersection represents the maximum value of the conversion that can be achieved for both CO and NOx. The higher this intersection point, the better the dynamic characteristics of catalytic activity of the catalyst, respectively, of the catalytic Converter. The intersection point was determined when the exhaust gas temperature of 400°C.
The results of these determinations are presented in table 4. Each value is the average of the values of several definitions. The point of intersection of several depend on the direction of change in the lambda value. The numbers in table 4 are average values obtained by changing the lambda values in accordance with changing conditions from a rich mixture to the poor and from lean to rich. In addition to the results of these determinations were averaged results definitions for multiple cycle the changes in lambda values when conditions change from a rich mixture to the poor and from lean to rich.
|1 Hz ± 0,5||1 Hz ± 1,0|
Table 4 provides the evidence suggests that the proposed according to the invention the catalyst K2 exhibits a significantly improved dynamic characteristic of their catalytic activity, although its working temperature T50%slightly different from the operating temperature of the comparative catalysts. The difference between the CTE is the group of transformations at the point of intersection for the catalyst according to the invention and comparative catalysts would be even more pronounced in cases of higher temperatures of the exhaust gas during aging (e.g., at 950°instead 850°before entering the catalyst).
Another catalyst, K3, was prepared as catalyst K2.
Comparative example 5
To improve thermal stability aluminiumoxide component of the catalytic composition and to improve the degree of conversion of NOxthe catalyst dispersion for coatings often add the barium oxide in the form of barium hydroxide. To study the effect of barium oxide on the catalytic activity in the case of aging at the termination of the fuel supply was preparing comparative catalyst SC. SC was a variant of the catalyst K3. In dispersion for the first layer, the content of La/Al2O3reduced from 70 to 60 g/l, but instead was added 10 g/l of barium oxide in the form of barium hydroxide.
Comparative example 6
Comparative catalyst S was prepared analogously to example 1 in US 5200384. In the preparation of dispersions for coatings used active aluminum oxide with a specific surface area of 140 m2/g, cerium oxide with a specific surface area of 80 m2/g, carbonate and zirconium mixed oxide in the form of the dioxide of zirconium/cerium oxide (with a mass ratio of 80/20). The mass ratio between platinum and rhodium was set equal to 2:1, and the total concentration of the oxide components in the composition for coating of the γ-aluminum oxide which I obtained catalyst was increased to 160 g/L. The process of preparation of the catalyst was performed as close as possible to the method described in example 1 of US 5200384. As it said on the active alumina besieged entirely and platinum, and rhodium. With this purpose used (EA)2Pt(OH)6and rhodium nitrate.
The finished catalyst had the following composition: 1.06 g/l (30 g/ft3) platinum plus rhodium; the mass ratio between platinum and rhodium: 2:1; 102,4 g/l of aluminum oxide; 38,4 g/l of cerium oxide; 6.4 g/l of Zirconia (zirconium carbonate) and 12.8 g/l of zirconium oxide/cerium oxide. The concentration of all oxide components in the catalyst was 160 g/l
Comparative example 7
Comparative catalyst S was prepared analogously to example 1 in US 4965243. In the preparation of dispersions for coatings used active aluminum oxide with a specific surface area of 140 m2/g, cerium oxide with a specific surface area of 80 m2/g zirconium dioxide with a specific surface area of 100 m2/g and barium hydroxide. The mass ratio between platinum and rhodium was set equal to 2:1, and the total concentration of the oxide components in the composition for coating of the γ-aluminum oxide in the obtained catalyst was increased to 160 g/L. the Process of preparation of the catalyst was performed as close as possible to the method described in example 1 of US 4965243. As it said on the active OK the ideal aluminum besieged entirely and platinum, and rhodium. With this purpose used (EA)2Pt(OH)6and rhodium nitrate.
The finished catalyst had the following composition: 1.06 g/l (30 g/ft3) platinum plus rhodium; the mass ratio between platinum and rhodium: 2:1; to 85.2 g/l of aluminum oxide; 48,7 g/l of cerium oxide; 17 g/l of zirconium dioxide and 9.1 g/l barium oxide (barium hydroxide).
Evaluation of catalysts K3, SC, SC and SK
These four catalyst was subjected to aging for the above, and then to determine the parameters given in table 4, was carried out by the same test methods as described above. The parameters of the intersection points determined at 400°modulation frequency of the lambda value of 1 Hz with amplitude ±0,5 a/T and at 450°modulation frequency of the lambda value of 1 Hz with amplitude ±1.0 In/So the Results are summarized in table 5.
|1 Hz ± 0,5||1 Hz ± 1,0|
For the comparative catalyst SC to determine the point of intersection at 450°it was impossible.
The intersection point transformations for the comparative catalyst SC were significantly lower than the corresponding values for the catalyst K3. This is attributed to the undesirable influence of barium oxide to platinum in terms of aging at the termination of the fuel supply. Aging at the termination of the fuel supply leads to the transformation of platinum in platinum and, consequently, to the loss of catalytic activity. This is also true for the comparative catalyst SK, for which after aging at the termination of fuel flow to determine the point of intersection at 450°it was impossible.
1. A single layer of a highly efficient catalyst for cleaning exhaust gases of internal combustion engines, comprising an inert carrier-based catalytic coating containing platinum, rhodium and oxide material substrate, characterized in that the catalytic coating includes
a) men who she least one first material of the substrate, selected from the group comprising the first active aluminum oxide enriched in cerium oxide mixed oxide constituting the oxide of cerium/zirconium dioxide, and zirconocenes component, and at least one first material substrate as a catalytic component, enter the first part of the total amount of platinum in the catalyst, where the concentration of the first partial quantity of platinum is in the range from 0.01 to 5 wt.% calculated on the total mass containing catalysts materials, and
b) the second material is a substrate, in which as a catalytic component enter the second part of the total amount of platinum and rhodium, and the second material substrate is a second active alumina, where the concentration of platinum plus rhodium on the second material of the substrate is in the range from 0.5 to 20 wt.% calculated on the total weight of the second material of the substrate.
2. The catalyst according to claim 1, characterized in that the total mass ratio of platinum/rhodium in the catalyst is chosen in the range of 10:1-1:5.
3. The catalyst according to claim 1, characterized in that platinum and rhodium are contained on the second active aluminium oxide at a mass ratio of platinum/rhodium 3:1-1:5.
4. The catalyst according to claim 1, characterized in that platinum and rhodium are contained in the catalytic coating in concentrations of 0.05-10 wt.% in baresch the ones on the total weight of the coating.
5. The catalyst according to claim 1, characterized in that platinum and rhodium are contained on the second active aluminum oxide in tight contact with each other.
6. The catalyst according to claim 1, characterized in that the first and second active aluminum oxide stabilized with 0.5-25 wt.% oxide of lanthanum, cerium oxide, yttrium oxide, neodymium oxide, gadolinium oxide, or mixtures thereof.
7. The catalyst according to claim 1, characterized in that the mixed oxide constituting the oxide of cerium/zirconium dioxide, contains 60 to 90 wt.% cerium oxide, calculated on the total weight of the mixed oxide and additionally stable oxide of praseodymium, yttrium oxide, neodymium oxide, lanthanum oxide, gadolinium oxide or mixtures thereof.
8. The catalyst according to claim 1, characterized in that zirconocenes component is additionally stabilised by 0.5 to 55 wt.% cerium oxide, yttrium oxide, neodymium oxide, lanthanum oxide, praseodymium oxide, gadolinium oxide or their mixtures, resulting zirconium dioxide is contained in an amount which equals or exceeds the amount of cerium oxide.
9. The catalyst according to claim 8, characterized in that zirconocenes component is a zirconium dioxide or zirconium dioxide, optionally stabilized with 0.5-10 wt.% yttrium oxide, cerium oxide, neodymium oxide, lanthanum oxide, praseodymium oxide, gadolinium oxide, or mixtures thereof.
10. Katal is congestion in one of claims 1 to 9, characterized in that the carrier-the Foundation is in a cellular form with many passing through it almost parallel channels, and these channels are defined by walls on which the catalytic coating is applied in amounts from about 50 to 250 g/l of the volume of the media.
11. The catalyst according to claim 10, characterized in that the first active aluminum oxide is contained in the amount of 0-150 g/l, mixed oxide constituting the oxide of cerium/zirconium dioxide, contained in the amount of 10-100 g/l and zirconocenes component is contained in an amount of 0-80 g/l
12. The catalyst according to claim 11, characterized in that the second active alumina is contained in an amount of 5-50 g/l
13. The catalyst according to item 12, wherein the catalytic coating further comprises from about 1 to 30 g/l Nickel, iron or manganese component.
14. The method of preparation of a catalyst for cleaning exhaust gases of internal combustion engines according to any one of the preceding paragraphs, characterized in that it includes
a) preparation of an aqueous dispersion of at least one first material of the substrate injection solution hexahydroxy ethanolamine (IV) in the dispersion and regulation of the pH of the resulting dispersion acetic acid to bring this value below 7,
b) preparation of water is isperia from the second active alumina, injection solution hexahydroxy ethanolamine (IV) in this dispersion,
C) subsequent injection into the dispersion for coatings with stage b) aqueous acidic compounds of rhodium precursor and regulation of the pH of this dispersion acetic acid to bring this value up to 6-8 with obtaining thus the second active alumina, including as a catalytic component, platinum/rhodium,
g) combining the dispersion from stage a) and stage (C) obtaining a composition for coating
d) use of the composition for coating when applied to a monolithic carrier-based catalytic coating and
e) drying and calcining the monolith media coverage.
15. The method according to 14, wherein the primary connection-the platinum precursor is hexahydroxy ethanolamine (IV)and the acid compound, the precursor rhodium is a rhodium nitrate.
16. The method of preparation of a catalyst for cleaning exhaust gases of internal combustion engines according to any one of claims 1 to 13, characterized in that it includes
a) impregnation of at least one first material of the substrate in an aqueous solution of a soluble compound of the platinum precursor, drying and calcining the impregnated materials for thermal C is mounting on it platinum,
b) preparation of an aqueous dispersion of material from step a), containing a catalytic component platinum
C) preparation of an aqueous dispersion of the second active alumina, injection into the dispersion solution of the compound of the platinum precursor,
g) subsequent injection into the dispersion for coatings with stage V) aqueous solution of acidic compounds of rhodium precursor and regulation of the pH of this dispersion acetic acid to bring this value up to 6-8 with obtaining thus the second active alumina, including as a catalytic component, platinum/rhodium,
d) combining the dispersion with phase b and phase d) obtaining a composition for coating
e) use of the composition for coating when applied to a monolithic carrier-based catalytic coating and
f) drying and calcining the monolith media coverage.
17. The method according to item 16, wherein the connection-the platinum precursor is hexahydroxy ethanolamine (IV)and the acid compound, the precursor rhodium is a rhodium nitrate.
FIELD: catalyst preparation methods.
SUBSTANCE: invention relates to a method for preparing catalyst and to catalyst no honeycomb-structure block ceramic and metallic carrier. Preparation procedure includes preliminarily calcining inert honeycomb block carrier and simultaneously applying onto its surface intermediate coating composed of modified alumina and active phase of one or several platinum group metals from water-alcohol suspension containing, wt %: boehmite 15-30, aluminum nitrate 1-2, cerium nitrate 4-8, 25% ammonium hydroxide solution 10-20, one or several precipitate group metal salts (calculated as metals) 0.020-0.052, water-to-alcohol weight ratio being 1:5 to 1:10; drying; and reduction. Thus prepared catalyst has following characteristics: specific coating area 100-200 m2/g, Al2O3 content 5-13%, CeO2 content 0.5-1,3%, active phase (on conversion to platinum group metals) 0.12-0.26%.
EFFECT: simplified technology due to reduced number of stages, accelerated operation, and high-efficiency catalyst.
5 cl, 1 tbl, 10 ex
FIELD: catalyst preparation methods.
SUBSTANCE: method involves preparing porous carrier and forming catalyst layer by impregnation of carrier with aqueous solution of transition group metal salts followed by drying and calcination. Porous catalyst carrier is a porous substrate of organic polymer material: polyurethane or polypropylene, which is dipped into aqueous suspension of powdered metal selected from metals having magnetic susceptibility χ from 3.6·106 to 150·106 Gs·e/g: iron, cobalt, chromium, nickel, or alloys thereof, or vanadium and polyvinylacetate glue as binder until leaving of air from substrate is completed, after which carrier blank is dried at ambient temperature and then fired at 750°C in vacuum oven and caked at 900-1300°C. Caked blank is molded and then subjected to rolling of outside surface to produce carrier having variable-density structure with density maximum located on emitting area. Formation of catalyst layer is achieved by multiple impregnations of the carrier with aqueous solution of acetates or sulfates of transition group metals: iron, cobalt, chromium, nickel, or alloys thereof in alternative order with dryings at ambient temperature and calcinations to produced catalyst bed 50-80 μm in thickness. In another embodiment of invention, formation of catalyst layer on carrier is accomplished by placing carrier in oven followed by forcing transition group metal carbonate vapors into oven for 60-120 min while gradually raising oven temperature to 850°C until layer of catalyst is grown up to its thickness 50-80 μm.
EFFECT: improved quality of catalyst and reduced its hydrodynamic resistance.
8 cl, 1 tbl, 3 ex
FIELD: catalyst preparation methods.
SUBSTANCE: invention relates to alumina-supported catalyst preparation method and employment thereof in reactions of nucleophilic substitution of aromatic halides containing electron-accepting group. In particular, alumina support impregnated with alkali selected from alkali metal hydroxides is prepared by treating alkali metal hydroxide aqueous solution with aluminum oxide in organic solvent followed by drying thus obtained catalyst mixture at temperature not lower than 150°C. Catalyst is, in particular, used to introduce electron-accepting protective groups into organic compounds comprising at least one of -OH, -SH, and -NH, as well as in reaction of substituting amino, thio, or ether group for halogen in a haloarene and in preparation of 2-puperidinobenzonitrile.
EFFECT: simplified preparation of catalyst and regeneration of spent catalyst, and avoided involvement of dangerous reactants.
11 cl, 20 ex
FIELD: catalyst preparation methods.
SUBSTANCE: catalyst containing crystalline anatase phase in amount at least 30% and nickel in amount 0.5 to 2% has porous structure with mean pore diameter 2 to 16 nm and specific surface at least 70 m2/g. When used to catalyze photochemical reaction of isolation of hydrogen from water-alcohol mixtures, it provides quantum yield of reaction 0.09-0.13. Preparation of titanium dioxide-based mesoporous material comprises adding titanium tetraalkoxide precursor and organic-nature template to aqueous-organic solvent, ageing reaction mixture to complete formation of spatial structure therefrom through consecutive sol and gel formation stages, separating reaction product, and processing it to remove template. Invention is characterized by that water-alcohol derivative contains no more than 7% water and template consists of at least one ligand selected from group of macrocyclic compounds, in particular oxa- and oxaazamacrocyclic compounds containing at least four oxygen atoms, and/or complexes of indicated macrocyclic compounds with metal ions selected from group of alkali metals or alkali-earth metal metals, or f-metals consisting, in particular, of lithium, potassium, sodium, rubidium, cesium, magnesium, calcium, strontium, barium, lanthanum, and cerium used in amounts from 0.001 to 0.2 mole per 1 mole precursor. Sol is formed by stirring reaction mixture at temperature not higher than 35°C. Once formation of spaced structure completed, mixture is held at the same temperature in open vessel to allow free access of water steam and, when template is removed from the mixture, mixture is first treated with nickel salt solution and then with alkali metal borohydride solution until metallic nickel is formed.
EFFECT: increased sorption and photocatalytic properties of catalyst and enabled reproducibility of its property complex.
7 cl, 68 ex
FIELD: organic synthesis catalysts.
SUBSTANCE: invention provides improved method for preparing catalyst for synthesis of N-methylaniline from aniline and methanol. Method comprises impregnation of alumina carrier with copper nitrate solution, to which were added nitrates of modifying metals selected from group consisting of manganese, chromium, iron, cobalt, and zinc, after which impregnated carrier is dried at temperature ensuring effective conversion of deposited nitrates into oxides of corresponding metals. When calcined, catalyst is subjected to additional impregnation with copper ammine solution, wherein Cu content (on conversion to oxide) lies within 0.6 to 7.0% based on the weight of catalyst, then dried at 100-120°C, and re-calcined at 230-250°C. After first calcination Cu content is 10.1-13% and after the second it rises by 0.6-5.0%. Lifetime of catalyst increases by a factor of 1.3 to 2.
EFFECT: increased lifetime of catalyst.
1 tbl, 12 ex
FIELD: industrial organic synthesis catalysts.
SUBSTANCE: invention relates to environmentally friendly processes for production of isoalkanes via gas-phase skeletal isomerization of linear alkanes in presence of catalyst. Invention provides catalyst for production of hexane isomers through skeletal isomerization of n-hexane, which catalyst contains sulfurized zirconium-aluminum dioxide supplemented by platinum and has concentration of Lewis acid sites on its surface 220-250 μmole/g. Catalyst is prepared by precipitation of combined zirconium-aluminum hydroxide from zirconium and aluminum nitrates followed by deposition of sulfate and calcination in air flow before further treatment with platinum salts. Hexane isomer production process in presence of above-defined cat is also described.
EFFECT: increased catalyst activity.
5 cl, 2 tbl, 6 ex
FIELD: gas treatment catalysts.
SUBSTANCE: catalyst preparation method comprises depositing initially liquid soda glass onto metallic or glass-cloth surface, after which transition metal oxide mixture is sputtered onto wet surface, said transition metal oxide mixture containing, wt %: chromium (III) oxide 18-35, manganese (IV) oxide 18-35, alumina - the rest; or cupric oxide 5-15, chromium (III) oxide 10-15, alumina - the rest; or cupric oxide 12-35 and alumina - the rest. Resulting coating is dried in air during 1 day and then molded through stepwise heat treatment to temperature 400°C, which temperature is maintained for 2-2.5 h.
EFFECT: prolonged lifetime at the same catalytic efficiency.
FIELD: petroleum processing and petrochemistry.
SUBSTANCE: invention relates to catalysts for isomerization of paraffins and alkylation of unsaturated and aromatic hydrocarbons contained in hydrocarbon stock. Catalyst of invention is characterized by that it lowers content of benzene and unsaturated hydrocarbons in gasoline fractions in above isomerization and alkylation process executed in presence of methanol and catalyst based on high-silica ZSM-5-type zeolite containing: 60.0-80.0% of iron-alumino-silicate with ZSM-5-type structure and silica ratio SiO2/Al2O3 = 20-160 and ratio SiO2/Fe2O3 = 30-550; 0.1-10.0% of modifying component selected from at least one of following metal oxides: copper, zinc, nickel, gallium, lanthanum, cerium, and rhenium; 0.5-5.0% of reinforcing additive: boron oxide, phosphorus oxide, or mixture thereof; the rest being alumina. Preparation of catalyst includes following steps: hydrothermal crystallization of reaction mixture at 120-180°C during 1 to 6 days, said reaction mixture being composed of precursors of silica, alumina, iron oxide, alkali metal oxide, hexamethylenediamine, and water; conversion of thus obtained iron-alumino-silicate into H-iron-alumino-silicate; further impregnation of iron-alumino-silicate with modifying metal compound followed by drying operation for 2 to 12 h at 110°C; mixing of dried material with reinforcing additive, with binder; mechanochemical treatment on vibrating mill for 4 to 72 h; molding catalyst paste; drying it for 0.1 to 24 h at 100-110°C; and calcination at 550-600°C for 0.1 to 24 h. Lowering of content of benzene and unsaturated hydrocarbons in gasoline fractions in presence of above catalyst is achieved during isomerization and alkylation of hydrocarbon feedstock carried out at 300-500°C, volumetric feedstock supply rate 2-4 h-1, weight ratio of hydrocarbon feedstock to methanol 1:(0.1-0.3), and pressure 0.1 to 1.5 MPa. In particular, hydrocarbon feedstock utilized is fraction 35-230°C of hydrostabilized liquid products of pyrolysis.
EFFECT: facilitated reduction of benzene and unsaturated hydrocarbons in gasoline fractions and other hydrocarbon fuel mixtures.
3 cl, 1 tbl, 13 ex
FIELD: petrochemical process catalysts.
SUBSTANCE: preparation of crusted metallic catalyst comprises: (i) applying suspension containing diluent, catalytically active metal selected from cobalt and ruthenium groups, and optionally first refractory element (atomic number at least 20) oxide onto surface of carrier particles to form wet coating and (ii) removing at least part of diluent from wet coating, said suspension containing at least 5% by weight of catalytically active metal based on the weight of calcination residue, which would result after drying and calcination of suspension. Crusted metallic catalyst itself and hydrocarbon production process are also described.
EFFECT: simplified catalyst preparation technology, improved physicochemical properties of catalyst as well as selectivity thereof, and increased productivity of hydrocarbon production process.
10 cl, 1 tbl, 3 ex
FIELD: industrial organic synthesis.
SUBSTANCE: invention is dealing with catalysts showing high catalytic stability in production of chloroform from carbon tetrachloride via catalytic dehydrochlorination reaction. Catalyst containing γ-alumina-supported platinum is characterized by that platinum in the form of particles 1 to 12 nm in size is distributed throughout the bulk of microspheric γ-alumina particles having median diameter 30 to 70 μm and pore volume 0.3 -0.6 cm3/g. Preparation of catalyst involves impregnation step accomplished via spraying γ-alumina with aqueous platinum compound solution used in amount equal to or less than alumina pore volume followed by platinum compound reduction step, wherein this compound is deposited onto γ-alumina with aqueous solution of formic acid or alkali metal formate.
EFFECT: achieved retention of high catalyst activity and selectivity over a long time period without being preliminarily activated.
9 cl, 2 tbl, 4 cl
FIELD: industrial organic synthesis catalysts.
SUBSTANCE: in order to increase CO-into-hydrocarbons conversion, invention provides alumina-supported catalyst containing 10-20% active Co component (calculated as CoO), 0.1-1.0% promoter F, and 0.3-1.0% platinum group metal or first transition series metal promoters or mixtures thereof.
EFFECT: increased CO conversion.
2 tbl, 8 ex
FIELD: gas treatment.
SUBSTANCE: catalyst contains alumina-supported palladium oxide, 0.80-2.54%, copper salt, 3.09-11.79%, promoter represented by phthalocyanine complex with iron or cobalt, 0.10-1.00%, and 0.50-3.00% of polyatomic alcohol.
EFFECT: enhanced efficiency of removing carbon monoxide as well as accompanying sulfur-containing impurities.
1 tbl, 21 ex
FIELD: production of catalytic neutralizers.
SUBSTANCE: high-efficiency catalytic neutralizer has internal and external layers on inert carrier which contain noble metals of platinum group deposited on materials of base and oxygen-accumulating components. Inner layer of proposed catalytic neutralizer contains platinum deposited on first base and first oxygen-accumulating component and its external layer contains platinum and rhodium deposited on second base only; this second layer contains additionally second oxygen-accumulating component. Production of catalytic neutralizer includes application of coat on carrier made from composition containing powder-like materials including first material of base and first oxygen-accumulating component followed by drying, calcining, immersing the carrier with coat in solution of platinum precursor; coat is calcined and external layer is applied over previous layer. Specification describes two more versions of production of catalytic neutralizer.
EFFECT: enhanced ability of catalytic neutralizer for reduction of catalytic activity after aging due to discontinuation of delivery of fuel.
24 cl, 1 dwg, 11 tbl, 5 ex, 3 ex
FIELD: catalysts of selective hydrogenation of alkynes of C4 fractions.
SUBSTANCE: proposed catalyst contains 1-30 mass-% of copper used as first active component, 0.001-5 mass-% of palladium used as second active component, at least 0.001-6 mass-% of one metal selected from Al, Pt, Pb, Mn, Co, Ni, Cr, Bi, Zr and Mo as co-catalyst; the remainder being one carrier selected from aluminum oxide, silicon dioxide and titanium oxide. Method of production of catalyst includes impregnation of carrier calcined preliminarily with solutions of active components depending on their content in catalyst. Alkynes are removed from C4 fractions enriched with alkynes by means of selective hydrogenation with the use of said catalyst.
EFFECT: enhanced selectivity and stability of catalyst.
31 cl, 2 tbl, 13 ex
FIELD: petrochemical process catalysts.
SUBSTANCE: cobalt-based catalyst precursor is prepared by impregnation of porous catalyst carrier particles with cobalt salt followed by partial drying and subsequent calcination of impregnated carrier, after which calcined product is partially reduced, impregnated with cobalt salt, partially dried and finally calcined. Preparation of Fischer-Tropsch catalyst comprises similar preparation of precursor thereof and reduction of the latter.
EFFECT: increased catalytic activity.
12 cl, 3 dwg, 1 tbl, 2 ex
FIELD: industrial organic synthesis.
SUBSTANCE: invention provides a method for preparing improved oxirane hydroformylation catalyst, improved oxirane hydroformylation catalyst, and single-stage process for production of 1,3-diol in presence of such catalyst. Preparation of catalyst comprises preparing complex A by contacting ruthenium(0) compound with di-tertiary phosphine ligand and preparing complex B via redox reaction of complex A with cobalt(0) carbonyl compound. Single-stage 1,3-diol production process involves reaction of oxirane with synthesis gas under hydroformylation conditions in inert solvent in presence of aforesaid catalyst, where recovery of product is preferably accomplished through separation of product-rich phase.
EFFECT: reduced number of stages to a single one or increased yield of 1,3-diol without by-products and preserved catalytic activity after catalyst regeneration operation.
10 cl, 3 dwg, 6 tbl, 21 ex
FIELD: petrochemical processes catalysts.
SUBSTANCE: fischer-Tropsch process catalyst constituted by cobalt deposited on granulated halumine may further contain promoters selected from oxides ZrO2 and HfO2 and metals Ru, Pd, and Pt.
EFFECT: increased selectivity and productivity.
2 cl, 3 tbl, 2 ex
FIELD: petrochemical process catalysts.
SUBSTANCE: fischer-Tropsch process catalyst constituted by cobalt deposited on aluminum metal may additionally contain promoters selected from oxides ZrO2, La2O3, K2O and metals Re, Ru, Pd, and Pt.
EFFECT: increased heat conductivity and selectivity.
2 cl, 2 tbl, 2 ex
FIELD: selective oxidation of carbon monoxide in hydrogen-containing stream.
SUBSTANCE: invention relates to method for selective oxidation of carbon monoxide to carbon dioxide in raw material containing hydrogen and carbon monoxide in presence of catalyst comprising platinum and iron. Catalyst may be treated with acid. Certain amount of free oxygen is blended with mixture containing hydrogen and carbon monoxide to provide second gaseous mixture having elevated ratio of oxygen/carbon monoxide. Second gaseous mixture is brought into contact with catalyst, containing substrate impregnated with platinum and iron. Carbon monoxide in the second gaseous mixture is almost fully converted to carbon dioxide, i.e. amount of carbon monoxide in product stream introduced into combustion cell is enough small and doesn't impact on catalyst operation characteristics.
EFFECT: production of hydrogen fuel for combustion cell with industrial advantages.
13 cl, 1 tbl, 4 ex
FIELD: industrial organic synthesis catalysts.
SUBSTANCE: catalyst contains following active components: Pd (0.001-1%), Bi (0.001-5%), at least of Ag, Cu, Zn, K, Na, Mg, Ca, Be, Sn, Pb, Cd, Sr, Ba, Ra, Mn, Zr, Mo, and Ge (0.001-10%), and at least one of rare-earth metals deposited on porous inorganic carrier (the balance.). Catalyst is capable of selectively and rapidly hydrogenating strongly unsaturated hydrocarbons such as alkynes. Catalyst is suitable for industrial cracking process and is characterized by favorable long regeneration period, long service time, and low cost.
EFFECT: improved performance characteristics of catalyst at low cost.
23 cl, 5 tbl, 22 ex