Method of obtaining oxide catalysts on a substrate
SUBSTANCE: invention pertains to the method of obtaining porous substances on a substrate for catalytic applications, to the method of obtaining porous catalysts for decomposition of N2O and their use in decomposing N2O, oxidising ammonia and reforming methane with water vapour. Description is given of the method of obtaining porous substances on a substrate for catalytic applications, in which one or more soluble precursor(s) metal of the active phase is added to a suspension, consisting of an insoluble phase of a substrate in water or an organic solvent. The suspension undergoes wet grinding so as to reduce the size of the particles of the substrate phase to less than 50 mcm. The additive is added, which promotes treatment before or after grinding. A pore-forming substance is added and the suspension, viscosity of which is maintained at 100-5000 cP, undergoes spray drying, is pressed and undergoes thermal treatment so as to remove the pore-forming substance, and is then baked. Description is also given of the method of obtaining porous catalysts on a substrate for decomposing N2O, in which a soluble cobalt precursor is added to a suspension of cerium oxide and an additive, promoting treatment, in water. The suspension is ground to particle size of less than 10 mcm. A pore-forming substance, viscosity of which is regulated to approximately 1000 cP, is added before the suspension undergoes spray drying with subsequent pressing. The pore-forming substance is removed and the product is baked. Description is given of the use of the substances obtained above as catalysts for decomposition of N2O, oxidation of ammonia and reforming of methane with water vapour.
EFFECT: obtaining catalysts with homogenous distribution of active phases and uniform and regulated porosity for optimisation of characteristics in catalytic applications.
The scope of the invention
The present invention relates to a universal method for producing a granular catalysts with different distribution of the active phase and an adjustable porosity. Requirements distribution of active phases and controlled porosity are determined by the characteristics inherent in the catalytic reaction (application), and may vary in accordance with the proposed method.
Description of the prior art,
The manufacture of the catalyst is carried out in some pretty difficult stages that depend on a large number of variables that are difficult to regulate at the same time.
Traditionally, large-scale manufacture of the catalyst includes two main approaches. The first is the method of co-precipitation. The second includes the impregnation of prior carrier (substrate) a precursor of the active phase or by the method of initial moisture content, or by an ion exchange method.
In the manufacture of the catalyst by coprecipitation of the components of the catalyst was prepared in the form of a solution and mixed in the appropriate ratios and concentrations. Phase catalyst precursor, typically a carbonate, hydroxide or oxide, is produced by adding a precipitating agent to the solution of the catalyst. Usually as a precipitator use the hydroxides or carbonates of alkali metals. Cree is practical parameters are the mixing, the regulation of pH and temperature. The suspension of catalyst precursor maintain that it has become more favorable morphology or structure. To facilitate filtration or centrifugation can add flocculants, and the solid precursor is separated from the liquid phase.
The precursor is washed to remove undesirable cations or anions. You may need to re-suspendirovanie and conduct ion exchange for the removal of adsorbed ions of alkali metals. The precursor is dried and then calcined to obtain the oxide phase. At this stage, the catalyst can be re-suspended for the deposition of additional phases.
If the pellets have to be formed by extrusion in the form of the oxide granularit to obtain a flowable powder, for example, by re-suspension and spray drying or fluidized bed or in a rotary granulator. Add additives for processing, for example lubricants, and then the granules formed into pellets, followed by heat treatment to obtain granules of the required strength.
Typical receive operation catalyst impregnation are the following.
Impregnation by the initial moisture content:
Prepare the substrate for the catalyst. This process involves a lot of individual operations, the including or extrusion and heat treatment paste the substrate, or granulation, tableting and heat treatment paste the substrate. Active phase receive in the form of a solution. Phase substrate is impregnated with a solution of the active phase. The impregnated granules are dried and subjected to heat treatment.
The loading of the active metal can be adjusted by adjusting the concentration of the metal precursor in the solution. If you want a high concentration of the active phase or if the solubility of the precursor is low, you may need several cycles of impregnation - treatment. In addition, it is difficult to specify the content of the metal. Several cycles may also be required when it is necessary to obtain bimetallic catalysts. The most important stage of this method is the drying process. If it is desirable to achieve uniform distribution of the active phase, the necessary quick drying. It is difficult to implement in large-scale way. Slow drying leads to segregation of the active phase on the outside of the granules and the uneven distribution of the active phase. This can have a negative effect on the catalytic properties of this substance.
Prepare the substrate for the catalyst. The substrate is dipped in a dilute solution of the active phase. Establish such a pH that the ion exchange of the active phase occurs with surface groups on the surface of the substrate. The pellets p is washed to remove ions of the active phase, not adsorbed on the surface of the substrate, and then thermally treated. The active phase will tend evenly distributed in the pellet, but its concentration is low. The maximum concentration of the active phase, which can be obtained will be limited ion exchange capacity of the phase of the substrate and/or solubility of a saturated solution of the active phase.
There are also other ways of obtaining oxide catalysts.
From US patent No. 6107238 a method of producing a catalyst with high resistance to abrasion, containing enriched oxide surface layer, comprising obtaining a suspension containing particles of the catalyst, catalyst precursor or substrate to catalyst (for example, transition metal oxides), colloidal Sol of oxide (for example, colloidal silicon dioxide) and a solution of solvent and solute, in which the dissolved substance consists essentially of the predecessor specified enriched oxide surface with a particle size of not greater than 5 nm (e.g., aqueous silicic acid or polysilicon acid) and then spray drying the suspension with the formation of porous microspheres catalyst, abrasion resistant, and calcining the microspheres after spray drying. This catalyst is particularly climbed the n in the processes of oxidation, in which the oxidation is conducted by the oxidized form of the catalyst and obtained the recovered form of the catalyst is separately recovered (for example, the two-stage vapor-phase methods, carried out in reactors with recirculating solids reactor with the transfer layer or circulating fluidized bed reactor and the like).
The US patent No. 6130184 describes a method of obtaining a cobalt containing catalyst or catalyst precursor comprising (a) a process of mixing (1) titanium oxide or a precursor of titanium oxide, (2) liquid and (3) compounds of cobalt, which is at least partially insoluble in the amount of fluid with the formation of the mixture, (b) shaping and drying of the thus obtained mixture, and (C) calcining the resulting composition. The process of mixing can imagine mixing, grinding or kneading depending on the content of solids in the mixture. Forming catalyst may include tableting, granulation, extrusion, spray drying, or a method of putting hot oil. This method does not result in a catalyst with the desired properties, in particular, with adjustable metal distribution centers and porosity. Control of these parameters is essential for optimization of performance in catalytic applications.
On the target inventions
The object of the invention is to provide a simple method of obtaining catalysts generally suitable for industrial applications. The next object is to obtain an oxide catalyst on a substrate with a certain distribution of the active phase and an adjustable porosity. Another object is reproducible and simple method of producing catalysts for the decomposition of N2O. Another object is the application of these catalysts in various catalytic processes.
These and other objects of the invention are realized by a method described below. In addition, the invention is characterized by the claims.
The invention will be further illustrated by figure 1-9 on which:
figure 1 shows a comparison of unit operations in the traditional method of co-precipitation to obtain an oxide catalyst on a substrate and method of application spray (SDM), described in this application.
Figure 2 shows a micrograph obtained by the method of transmission electron microscopy (FACT), catalysts With/CEO2received by the SDM method, with different dispersion of the metal when using (A) a soluble precursor of cobalt (high dispersion) or (C) insoluble precursor of cobalt (low dispersion).
Figure 3 represents the porosity of the catalysts With/CEO2/sub> cylindrical pellets of 5 mm × 5 mm)obtained by the method of SDM, depending on the starch content (with respect to the contents CEO2after sintering in air for six hours at different temperatures.
Figure 4 represents the influence of the porosity of the catalyst on the diffusion coefficient of the gas and the radial crushing strength of the catalyst With/CEO2cylindrical pellets of 5 mm × 5 mm)obtained by the method of SDM.
Figure 5 shows the conversion of N2O depending on the temperature in the laboratory testing of catalysts With/CEO2(particle 125-200 μm), obtained by different methods: (a) SDM with soluble precursor of cobalt, (b) SDM with an insoluble cobalt precursor and (C) by the method of initial moisture content. Experimental conditions: flow = 3 mbar N2O, 20 mbar NOx, 80 mbar O2, 50 mbar H2Oh, total pressure = 2 bar, watch the volumetric rate of gas = 140000 h-1.
6 represents the selectivity for NO and the formation of N2O depending on the time during the oxidation of ammonia in the pilot testing of catalysts With/CEO2cylindrical pellets of 3 mm × 3 mm)obtained by the method of SDM c soluble precursor of cobalt and insoluble cobalt precursor. Experimental conditions: flow = 10,5% vol. NH3in the air, temperature = 900°C, total pressure = 5 bar, cha the new volumetric rate of gas = 60000 h -1.
Fig.7 represents the conversion of N2O depending on the time in the pilot testing of catalysts for Co2AlO4/SEO2cylindrical pellets of 5 mm × 5 mm), manufactured by the method of SDM with soluble precursor of cobalt by adding corn starch or without him. Experimental conditions: flow = 6.5 mbar N2About 50 mbar NOx, 30 mbar O2, 80 mbar H2Oh, temperature = 900°C, total pressure = 5 bar, watch the volumetric rate of gas = 100000 h-1.
Fig represents the conversion of N2O depending on the time in the pilot testing of catalysts for Co2AlO4/SEO2cylindrical pellets of 5 mm × 5 mm), manufactured by the method of SDM c soluble Co-precursor and corn starch, as well as by coprecipitation. Experimental conditions: flow = 6.5 mbar N2About 50 mbar NOx, 30 mbar O2, 80 mbar H2Oh, temperature = 900°C, total pressure = 5 bar, watch the volumetric rate of gas = 100000 h-1.
Fig.9 represents the catalytic activity of Ni/Al2O3made by the SDM method, the reforming reaction of methane with water vapor in laboratory tests and comparison with commercial catalyst based on Ni (G91-HGS, Sud-Chemie). The tests were carried out on the catalyst particles 300-500 μm. Experimental conditions: temperature = 650°C, supply = the hypoxia ratio of N 2O/CO2/CH4total gas flow = 125 IO h-1, 2 g of catalyst + 10 g α-Al2O3(diluent), total pressure = 25 bar, a mass hourly space velocity = 1000 nl h-1g-1pre-processing catalyst = net N2at 600°C for 12 h.
Thus, the invention relates to a method for producing a porous substances on the substrate for catalytic applications in which one or more soluble(s) precursor(s) of the active phase is added to a suspension consisting of insoluble phase substrate in water or in an organic solvent. The suspension is milled to reduce particle size and phase of the substrate(carrier) to a value of less than 50 microns, before or after grinding add additives that facilitate the processing, add a pore-forming substance and the suspension is subjected to spray-dried, pressed and thermally treated to remove the pore-forming substance. After that, the substance is sintered and preferably subjected to a preliminary treatment with hydrogen gas is a reducing agent or an inert gas.
Preferably, the suspension is subjected to wet grinding and particle size is reduced to 0.1-10 μm, preferably 1 μm. The viscosity of the suspension support at the level of 100-5000 JV, preferably about 1000 CP. A pore-forming substance is preferably I have is cellulose, starch or polymer fiber, is removed at a pressure of 10-20 mbar O2diluted with an inert gas at 300 to 400°C. the heating Rate is preferably chosen possibly low, usually 1°·min-1.
Phase substrate (carrier) represents one or more components selected from Al2O3, SiO2, ZrO2, TiO2, ZnO, MgO, MgAl2O4, CoAl2O4and CeO2. The active metal phase selected from transition metals (for example, Co, Ni, Cu, Fe), noble metals (such as Pt, Rh, Ru), lanthanides (e.g. La, Ce), as well as other elements of the Periodic table, which can act as stabilizers and / or promoters (alkaline earth, for example, Na, Mg, K, Cs) or other trivalent neustanovivshiesya metals (such as Al, Ga). The precursor of the active phase is one or more compounds selected from acetates, nitrates, sulfates, oxalates, acetylacetonates, preferably acetates. Cations of the active phase before adding to the suspension substrate can be bound in complexes with organic phase. You can also make partial complexation of cations, which operate to prevent the formation of large crystals. Additives that facilitate the processing, can provide dispersing agents, binders, plasticizers, lubr the edges, the pH modifiers, etc.
The invention also relates to a method for production of porous catalysts on the substrate for decomposition of N2O, in which the soluble precursor of cobalt is added to a suspension of cerium oxide and additives that processing in the water. After that, the suspension is milled to a particle size less than 10 microns, add a pore-forming agent, viscosity regulate to about 1000 SP before the suspension is subjected to spray-dried, and then pressed, remove the pore-forming substance and the product is sintered. You can add the zirconium oxide and/or a soluble compound of aluminum. It is preferable to use as the precursor of cobalt acetate.
The substance obtained according to the method, it is possible to use, for example, as a catalyst for the decomposition of N2O, the ammonia oxidation or reforming of methane with water vapor.
Detailed description of the invention
The present invention discloses a new simple, inexpensive, reproducible, uniform way that is easy to use on a large scale, producing high quality porous substances on the substrate for catalytic applications. The authors called his method of spray application (SDM). Figure 1 presents a comparison of unit operations in the method SDM and conventional coprecipitation method.
The main novelty of the JV is soba SDM this introduction one of the basic operations, i.e. spray drying, for simultaneously carrying out a large number of operations on the production of the catalyst:
i) applying a precursor(s) of metal on the substrate evenly over one stage;
ii) drying the catalyst precursor (avoiding subsequent separation of solid - liquid, such as filtration, centrifugation);
iii) introduction of additives that contribute to the processing (dispersants, binders, plasticizers, lubricants, modifiers, pH and the like);
iv) the granulation powder to obtain easily pressable powder.
After selecting the active form (compounds) and substrates for her, the challenge is to build from the predecessors of these active forms of the catalytic structure with properties and characteristics that will meet the requirements of the industrial customer. It was shown that the large scale production of catalysts for the decomposition of N2O by the method of spray application amounts to many tons. Methods such as coprecipitation and impregnation or ion exchange, lead to many serious technical problems when scaling compared to the SDM. Other methods, such as Sol-gel, inoculation (clutch), heterogenization complexes and deposition-precipitation is still used only in laboratory scale and only dlearning number of formulations. Catalysts synthesized by these methods are not produced on an industrial scale.
Soluble precursor of the active phase is first added to a suspension consisting of phase substrate in water or other organic solvent in appropriate quantities and concentrations. The slurry is subjected to wet grinding in the mill constantly stir environment, or a ball mill to reduce particle size and phase of the substrate, preferably to less than 1 μm, thus achieving a stable dispersion. To prepare the catalyst for forming additives that facilitate processing, such as dispersants, binders, plasticizers, lubricants and pH modifiers that can be added before or after grinding. After grinding to the suspension, you can add a pore-forming substance, such as starch, cellulose or polymer fibers. The suspension is subjected to spray drying to obtain granules, suitable for molding by extrusion in the form, i.e. with a size distribution from 50 to 400 microns.
Extremely fast drying, achieved when spray drying, allows to obtain the precursor of the active phase deposited on the surface of the phase of the substrate evenly over the entire spray dried granule. This stage plays a crucial role in the emergence of close contact between Akti is Noah phase and its predecessor, which leads to the uniform distribution of metal in the final catalyst. Then the substance is pressed. Removing a pore-forming substances should be conducted in a controlled atmosphere (10-20 mbar O2diluted with an inert gas, such as N2, He or Ar). Thermal decomposition of the pore-forming phase in an oxidizing atmosphere can kataliziruetsa metal of the active phase, leading to thermal destruction. This happens not only in the oxidation of starch and cellulose, which is ectothermic. Many polymer processing additives that decompose endothermically, even when heated in air, such as polymethylmethacrylate (emission spectra obtained for pure), decompose exothermically if heated by contact with a catalytic phases. The proposed method of removing a pore-forming substances is also considered as a new aspect of the present invention, which is generally applicable in the production of catalysts. After this process the substance is sintered at a high temperature and get the ultimate catalyst. The uniform distribution of the active phase in the granules, spray dried, preserved in the final product - the catalyst granules.
The method of spray application requires 3-5 unit operations, i.e. less than traditional methods such as coprecipitation and impregnation (see figure 1). Few operas is tion in the new method are multi-purpose, that makes it very attractive (see above).
The method of spray application provides the ability to get a wide range of catalysts on the substrate. The only requirement is to have a soluble active phase and the insoluble substrate. There are many opportunities to find appropriate precursors of the metals. You can use metals of different nature from the Periodic table of elements, while other methods have large restrictions.
This requirement meets traditional substrates used in catalysis (e.g., Al2O3, SiO2, ZrO2, TiO2, ZnO, CeO2, MgO, MgAl2O4, CoAl2O4). The active phase is selected from transition metals (for example, Co, Ni, Cu, Fe), noble metals (such as Pt, Rh, Ru), lanthanides (e.g. La, Ce), as well as other elements of the Periodic table, which can act as stabilizers and / or promoters (alkaline earth, for example, Na, Mg or Al, Ga. It is preferable to use the acetates, nitrates, sulfates, oxalates or acetylacetonates. Another feature of the method of spray application is the possibility of obtaining polymetallic catalysts with high dispersion of the components. This makes it attractive, for example, bifunctional catalysis or promoted the reaction is rd. Classic joint or sequential impregnation impregnation of the two metal salts has been shown to be not effective to achieve close cooperation between the two metals. Tested and new methods. In all cases, looking for a way to get monometallic catalyst (i.e. the source of catalyst), which is then modified by the addition of a second metal. This modification is carried out through selective reaction which takes place only on monometallic particles of the original catalyst. How SDM offers through operations in a single tank is a simple way to overcome this difficult and time-consuming manufacturing process, reaching very close contact of the introduced metals.
For the synthesis of bimetallic phases on a substrate the method of synthesis of the spray application can be further improved by linking the complex cations of the active phase with the organic phase before adding to the suspension substrate. This is a modification of the well-known Pechini method to obtain mixed metal oxides, in which the cations are bound in complexes with organic molecules, which undergo polymerization process. This approach leads to the formation of phase precursor containing chaotic dispersion of metal ions, which is then applied to mean the ku during spray drying. This ensures the formation of a mixed phase oxides at low temperatures. Suitable complexing agents include citric acid, glycine, EDTA, etc.
At high concentration of the active phase during the drying process, the granules can be formed large crystals of the active phase. This can be avoided by adding a small amount of monodentate complexing agents, such as triethanolamine (tea). This number must be less than the amount sufficient for complete bonding in complexes of cations of the active phase, preferably sufficient to bind each cation only one molecule of the complexing agents. The result of this partial complexation of the cation is that it prevents the formation of large crystals of the precursor of the active phase due to interruption of the crystal lattice.
How SDM universal that can be continuous or periodic, which contrasts with the high requirements to make way coprecipitation continuous. Scaling from pilot plant to full-scale production is relatively easy to implement in the framework of the SDM way that was demonstrated. The most important single operation, the grinding slurry and spray drying are standard operations in the processing of ceramics and Ho is Osho studied.
The method of spray application is well suited to achieve a uniform distribution of the catalyst components or creating predecessors with a specific stoichiometry. The final catalyst consists of small and dispersed mixed crystallites components due to the good contact of the active phase (for example, in bimetallic systems) and the substrate before and after the stage spray drying/coating. The coprecipitation also leads to high dispersion, but the technological requirements are much higher here, as well as the difficulties the quality of the precipitated product and the challenges of maintaining a constant product quality during the entire deposition process. Excellent characteristics of the catalyst, deposited by sputtering, in comparison with other methods were shown for the decomposition of N2O in the presence of catalysts based on Co.
How SDM also allows you to accurately design the macrostructure of the obtained catalyst (pore size and pore volume) for optimum performance. By this method were obtained solid granules with a porosity of 70%.
The method of producing catalyst
Further describes a method of producing catalyst, entitled "Method of spray application and disclosed in the claims. The method of obtaining described with reference to obtaining catalyst razloga the Oia N 2O, containing a pore-forming phase. Also covered other catalytic applications. It also describes the influence of the pore-forming phase on the properties of the catalyst to transfer gas. Further detail of each unit of operation in the method SDM presented in figure 1 for the catalyst With-Al/CeO2.
Aqueous suspension of cerium oxide or other phase substrate is prepared by adding to water their powder of cerium oxide c size agglomerates d50that usually lie in the range of 10-20 microns. For dispersion of the suspension and prevent sedimentation using vigorous stirring. To this suspension is added polyvinyl alcohol (PVA) in the form of 5-10 wt.% aqueous solution. As a rule, to dissolve the PVA PVA solution should be warmed. After adding PVA to its suspension is stirred for 12 hours. While PVA adsorbed on the surface of the cerium oxide. The role of PVA is twofold. In suspension it acts as a steric stabilizer cerium oxide, reducing the tendency to sedimentation. At a later stage of manufacture, it acts as a temporary binder for granules obtained by spray drying.
To a suspension of cerium oxide added with vigorous stirring cobalt acetate, hydroxyacetate aluminum and zirconium oxide. For some trains you can use nitrate or other is Oli. The suspension is milled using a ball mill or mills with continuous mixing media to reduce the size of agglomerates of cerium oxide, so that d50reduced to 0.1 to 10 μm (preferably 1 μm). This allows you to get the suspension is resistant to sedimentation, which is a practical advantage, and can improve the characteristics of the catalyst due to the improved uniformity of the catalyst. The viscosity of the slurry should be maintained at the level of 100-5000 JV, preferably about 1000 SP.
A pore-forming substance
To stable suspensions add a pore-forming substance. Use corn starch with an average particle size of 10-15 µm. The pore size can be adjusted by choice of starch. Other starches, such as rice or potato can be used to obtain smaller or larger pores, respectively. You can also use other pore-forming substances, other than starch. In the manufacture of catalysts according to the method SDM successfully applied microcrystalline cellulose Avicel.
In principle, it is possible to use any substance which is insoluble and thermally decomposed, leaving the inorganic residue. In the past alternatively, the starch used microcrystalline cellulose, although it did not give special advantages. Mo is but also use polymer beads or fibers, but if they melt before thermal decomposition, it may cause difficulties during heat treatment. Starch is added after grinding, so that the structure of starch grains, which causes the pore size is maintained. The water content of the suspension is set so that the viscosity of the suspension was 1000 SP.
Spray drying was performed on a pilot plant using a two-fluid atomizer and centrifugal atomizers. Full-scale spray drying is performed with the use of centrifugal atomizers and sprayers high pressure. In each case, no serious problems, and always get a good flowing powder. Once in full production, it was found that when using a spray gun high pressure in counter-current mode is too high, the inlet temperature may cause ignition of the powder. In this case, use the temperature at the inlet above 400°C. Countercurrent model is not ideal for substances that are sensitive to heat. Therefore, either the inlet temperature should be lower, which will lead to a reduction in the rate of production, or it is necessary to use a model of dispersion in parallel threads.
In our pilot tests, the inlet temperature typically ranged from 250 to 180°in the W ill feed rate of the suspension, and the outlet temperature was usually in the range of 105-110°C. This led to a moisture content of 0.2-0.5% and the average grain size d5060-80 microns.
Before pressing the powder, spray dried, was added 0.5% of aluminum stearate and the water content is brought to 0.5-2%. This operation was performed in a Forberg mixer. Water acts as a plasticizer for PVA, and the optimum water content depends on the exact composition of the catalyst. The required amount of water depends on the surface area of cerium oxide and purity PVA. The extruded pellets by uniaxial pressing on the press PTX Pentronix 612. For pellets of 5 mm or less acceptable mold single actions, but for the manufacture of larger granules, such as 9 mm corrugated granules, you must use the operation of double pressing. The compression ratio (the ratio between the depth of fill and the height of the pressed pellets) is usually equal to 2.2.
Removing a pore-forming substance
After pressing, the pellets are subjected to heat treatment to remove the pore-forming phase, after which it is sintered to the final obtain pellets of the catalyst. Heat treatment to remove the pore-forming starch is the most critical and crucial stage in the manufacture of the catalyst. The heated air granules containing starch, Pref which leads to a rapid rise in temperature in the stratum granulosum and unregulated burning of starch, that adversely affects the integrity of the granules. Heating of the granules in the nitrogen, to which is added a small amount of air, regulates the removal of starch. The range of concentrations of oxygen in the initial stages is 0.1 to 0.5 vol.%. At all stages of the removal of the starch, the main decomposition products of starch are the CO2and water vapor even when the oxygen content of 0.5%.
After removal of the weight of the starch, as evidenced by the lack of CO2in the exhaust gas, the oxygen content increases to 20 vol.%. Starch consists of two polymers, one of them is decomposed 170°and another in the range of 250-300°C. the heating Rate should be as low as possible, usually 1°·min-1. Pellets are loaded into a perforated basket and passed through a layer of granules from the bottom of the gas mixture of the nitrogen-oxygen. To purge through the granules gas heat. The temperature of the pellets regulate by means of gas temperature and oxygen concentration. During this operation the temperature of the layer is more sensitive to oxygen than the temperature of the inlet gas, so it is a means by which temperature can be regulated during decomposition. In the first stage, the pellets are heated to 170°With the gas stream containing 0.1 vol.% the oxygen. Once it reaches a stable temperature, the con is entrely oxygen is slowly increased. For the development of the reaction can be followed by the rise of temperature in baskets, arranged vertically in series. As soon as the first polymer of starch decompose, the oxygen concentration is reduced and the temperature was raised to 250°C. Upon reaching a stable temperature, the oxygen concentration again increased up until all baskets will not complete the second stage of decomposition. The temperature was raised to 300°and the oxygen concentration is increased to 20%, while the reaction will not stop. Baskets cooled overnight in a stream of oxygen. The total process time is typically 2.5 days.
After removal from the furnace for burning a pore-forming substance baskets are placed in a vertical tube furnace. They heat up in the air with a speed of 1°·min-1up to 950-1000°C. After 6-12 h at a maximum temperature of the furnace is cooled. The sintering process usually takes 2 days. Sintered pellets represent the final product.
Hereinafter the invention will be illustrated in the following examples:
Example 1. Obtaining catalysts Co/CeO2with different distribution of active phases and download metal method SDM
Example 1A. The catalyst with a high dispersion of cobalt oxide supported on cerium oxide
Aqueous suspension phase substrate of cerium oxide were prepared by adding 5 kg sogepa the scientists powder of cerium oxide (Rhodia HSA15) c size of the agglomerates d 50usually in the range of 10-20 μm to 5 l of water containing 40 g of PVA (Rhodoviol 25/140). For dispersion of cerium oxide used vigorous stirring, and then it was stirred for 15 hours to allow the PVA to be adsorbed on the surface of the cerium oxide.
To a suspension of cerium oxide was added 289 g of cobalt acetate (Fluka) with vigorous stirring. The suspension was ground in the mill continuously stir the environment to reduce the size of agglomerates of cerium oxide so that d50is less than 1 micron.
The water content of the suspension was adjusted so that the viscosity of the suspension is 1000 SP. Typically, the moisture content in the suspension is between 40 and 50%.
Spray drying can be carried out in the dryer with a centrifugal atomizer. The inlet temperature was usually 180-400°depending on the speed of injection of the suspension, and the outlet temperature was usually equal 105-110°C. as a result, the moisture content was 0.2-0.5 wt.% and the granules have a size of d50from 60 to 200 microns, depending on the type of spray.
Before pressing the powder, spray dried, was added 0.5 wt.% the aluminum stearate and the water content is brought to 0.5 wt.%. This operation was performed in a Forberg mixer. Water acts as a plasticizer for PVA, and the optimum water content depends on the exact composition of the catalyst. Not the required amount of water depends on the surface area of cerium oxide and purity PVA. The extruded pellets by uniaxial pressing on the press PTX Pentronix 612. Received the corrugated beads with seven channels (dm=9 mm, dh=1.7 mm). Can be obtained pellets of various shapes, from simple cylinders to a multilayer pellets. Pressed pellets were specaly in the air, using conventional muffle furnace. The pellets were heated at a rate of 1°·min-1900-1000°and kept at the maximum temperature for 6-12 hours. The chemical composition of the final catalyst consisted of 1.9 wt.% Co2About3and to 98.1 wt.% SEO2.
Example 1b. The catalyst with low dispersion of cobalt oxide supported on cerium oxide
Received a suspension of cerium oxide as described in example 1A, using 5 kg of cerium oxide (Rhodia HSA15) and 5 l of water containing 40 grams of dissolved PVA (Rhodoviol 25/140). To the aqueous slurry of cerium oxide was added to 93 g of cobalt oxide (Co3About4, Merck) with vigorous stirring. After 1 hour of stirring to ensure uniform dispersion of the cobalt oxide, the slurry was ground in a ball mill to reduce the size of agglomerates of cerium oxide to a value of d50less than 1 micron. The water content of the suspension was adjusted so that the viscosity of the suspension was 1000 SP. For spray drying, the addition of lubricants, extrusion pellets and sintering was performed as opisanoj example 1A. The chemical composition of the final catalyst consisted of 2.0 wt.% Co2About3and 98,0 wt.% SEO2.
Figure 2 shows the different composition of the catalyst relative to the active phase depending on the nature of the cobalt precursor used in the preparation. The use of a soluble precursor of cobalt (cobalt acetate, example 1A) leads to a highly dispersed catalyst (figa). In the micrograph, obtained by the method of transmission electron microscopy, high-resolution, are not visible particles of cobalt oxide, and it shows that the particles of cobalt oxide have a size of less than 1 nm. When using insoluble precursor of cobalt (Co3About4, example 1b) observed large agglomerates of cobalt oxide on the substrate SEO2(pigv), indicating less dispersion of the active phase in the final catalyst. A different composition of cobalt will undoubtedly affect the catalytic properties of substances, as shown in examples 4 and 5.
Example 2. Obtaining catalyst Ni/Al2O3way SDM
The catalyst is Nickel oxide deposited on a gamma-alumina, can be obtained according to the method described in example 1A. In 5 l of water were dissolved 40 g of PVA (Rhodoviol 25/140). With vigorous stirring, was added 5 kg of gamma-aluminum oxide (Sigma-Aldrich). The suspension was stirred for 15 h and then suspensie of aluminum oxide was added 3,175 kg of Nickel nitrate (Fluka). After stirring for 1 hour the suspension was ground using a ball mill to a value of d50equal to 1 μm. After grinding the moisture content in the suspension was 42.9% and the viscosity was equal to 960 SP that is suitable for spray drying. The suspension was subjected to spray-dried and granulated by the method described in example 1A. Pellets were specaly standard muffle furnace in air. The pellets were heated at a rate of 1°·min-1up to 700°C and held at this temperature for 6 hours. The chemical composition of the final catalyst consisted of 16.6 wt.% NiO and of 83.4 wt.% Al2O3.
Example 3. Obtaining catalysts With/CEO2with different porosity way SDM
How SDM preparation of catalysts allows to obtain catalysts with adjustable volume and pore sizes. This is achieved by introducing fugitive pore-forming phase, such as starch, cellulose or polymer, in a suspension of the catalyst prior to spray drying. After pressing, spray dried granules, pellets or tablets pore-forming phase is removed by means of controlled heat treatments.
Aqueous suspension of cerium oxide and cobalt acetate as described in example 1A, was prepared and crushed to the desired particle size. To the suspension was added with rapid stirring fugitive pore-forming the ABC - corn starch (Collamyl). The suspension containing phase catalyst and a pore-forming phase from corn starch, is subjected to spray drying by the method described in example 1b. After adding lube, aluminum stearate, and regulation of the moisture content of the granules, dried by spraying, got granules or pellets by uniaxial pressing in the form as described in example 1A.
To create a variable porosity while maintaining the mechanical integrity of the granules pore-forming phase, you must remove the regulated way. This is achieved by thermal oxidation of a pore-forming substance with a low partial pressure of oxygen. The atmosphere consists of air diluted with nitrogen so that the oxygen concentration is 0.1-2 vol.%. Corn starch is composed of two different polymers amylose and amylopectin. Amylose consists of linear chains of alpha-linked glucose, and amylopectin consists of a branched polymer of alpha-linked glucose. Usually corn starch consists of 75% amylopectin and 25% amylose. Both polymer decomposed at 240 and 380°respectively in contact with solids, for example, aluminum oxide. In the presence of the oxidation catalyst, the decomposition temperature can be reduced by 80-100°C. Burning corn starch from the catalyst cobal the t/cerium oxide, obtained by the method SDM involves slow heating of the surface layer of granules to 170°C. During the heating process through the layer of miss gas consisting of air diluted with nitrogen so that the oxygen concentration below 1 vol.%. Low oxygen concentration limit temperature rise in the layer of pellets due to oxidation of amylopectin, less than 50°C. After complete decomposition of amylopectin, as evidenced by the low level of carbon oxides in the exhaust gas, the temperature is slowly increased to 300°and maintain at this temperature until complete digestion of amylose. After removal of the starch granules are heated in air up to 900-1000°for sintering.
The starch content of the suspension was varied from 0 to 25 wt.% in the calculation of the mass of cerium oxide. It is possible to produce granules of the catalyst with a higher content of the pore-forming substance, but the mechanical properties of the pellets after removal of the pore-forming substance is very low.
Changing the amount of a pore-forming phase, it is possible to adjust the pore volume. Figure 3 shows the effect of starch content on the porosity of the granules in the system With/CEO2(nominal composition: 2 wt.% Co2About3and 98% SEO2) at different sintering temperatures. With increasing starch content in the composition is above 9%, the porosity of the granules increases. Dr. who and the properties of the critically determined by the porosity of the catalyst: the effective diffusion coefficient inside the granules compared with the diffusion coefficient of the gas in the free space, and the strength of the granules. These two properties for the system Co/CEO2shown in figure 4. The increase in porosity leads to an increase of the effective diffusion coefficient in the grain with reduced strength. Therefore, the optimum depends on the specific application.
Upon receipt of the granules or pellets by extrusion or by extrusion in the absence of a pore-forming phase receive a porosity in the range of 40-55%, provided that the sintering temperature is not very high. Pore size is determined by the size of the primary particles, which depends on the degree of grinding. The more efficient the process of crushing, the smaller the size of the pores between the particles. However, if the particle size less than one micron, a large proportion of the porosity will be less than 0.1-0.2 μm. By introducing a pore-forming phase can be increased and the porosity and pore size.
Example 4. Characteristics of catalysts With/CEO2in the direct decomposition of N2O
Catalysts With/CEO2(nominal composition: 2 wt.% Co2About3and 98% SEO2in the form of particles with a size of 125-200 μm, manufactured by different methods, were tested in the decomposition of N2O. the Results are shown in figure 5. Clearly the correlation between catalytic activity and the dispersion phase of cobalt. The catalyst obtained by the method SDM using cobalt acetate as a precursor for what it shows the highest activity due to the high degree of dispersion of cobalt in the catalyst. The catalyst obtained by the method SDM from cobalt oxide as the precursor, showed significantly less activity due to the low dispersion of the active phase, forming large agglomerates of cobalt oxide on the substrate SEO2(see figv). The catalyst With/CEO2obtained by the method of initial moisture content using cobalt acetate, lead to very low activity, which correlates with low dispersion obtained by this method.
Example 5. The influence of cobalt precursor on the characteristics of the catalysts With/CEO2in the oxidation of ammonia
Catalysts With/CEO2in the form of cylindrical pellets with a size of 3 mm × 3 mm, obtained by the method SDM using soluble and insoluble precursors of cobalt, were tested in the oxidation of ammonia (Fig.6). Both catalyst had chemical composition: 20 wt.% Co2About3and 80 wt.% SEO2. The catalysts showed similar initial selectivity NO (˜85%). However, the initial formation of N2O on the catalyst obtained with the use of cobalt acetate as a precursor, was significantly lower compared with the catalyst obtained with the use of cobalt oxide as the precursor. Moreover, both the catalyst vary greatly in stability. The catalyst With/CEO2obtained and the use of insoluble precursor of cobalt, deactivated much faster, which leads to lower selectivity and NO increased formation of N2O.
Example 6. The influence of the porosity of the granules on the characteristics of the catalysts of Co2AlO4/CeO2in the decomposition of N2O
Catalysts CoAl2O4/CeO2were obtained by the method SDM using cobalt acetate as its predecessor with the addition of corn starch or without him. Both catalyst had chemical composition: 1 wt.% Co2About3, 0,3% vol. Al2O3and 98 wt.% SEO2. Catalysts in the form of cylindrical pellets of 5 mm × 5 mm were tested in the direct decomposition of N2O to evaluate the influence of the porosity of the granules on the activity of the decomposition of N2O. the Results are shown in Fig.7. Adding starch has proven beneficial effect on performance; the catalyst starch (porosity pellets 65%) showed a slightly higher conversion of N2O than the catalyst with 15 wt.% starch (porosity of granules 50%).
Example 7. The influence of the method of obtaining catalysts of Co2AlO4/CeO2on the decomposition of N2O
The catalyst CoAl2O4/CeO2was obtained by the method SDM using cobalt acetate as a precursor and with the addition of corn starch (15 wt.% in calculating the masses SEO2). The final catalyst and the ate chemical composition: 1 wt.% Co 2About3, 0,3% vol. Al2O3and 98 wt.% SEO2. In addition, the catalyst CoAl2O4/CeO2was obtained by coprecipitation from a solution of precursors of Co, Al and CE (soluble) solution of the base sodium hydroxide and sodium carbonate. Aoademy catalyst had chemical composition: 42 wt.% Co2About3, a 13.9 wt.% Al2O3and of 42.7 wt.% SEO2. To assess activity in the decomposition of N2O used catalysts in the form of cylindrical pellets of 5 mm × 5 mm Fig results were compared. The catalysts obtained by the method SDM, have a high initial activity and stability throughout the work. There is a significant decontamination (˜20% of the initial activity after 30 days) of the catalyst obtained by coprecipitation. High dispersion of the cobalt cerium oxide facilitates a strong interaction between the active phase and the substrate, which stabilizes the composition. This cannot be achieved by conventional methods such as coprecipitation, as shown in the figure.
Example 8. Characteristics of catalysts based on Ni in the reforming process of methane
The activity of the catalyst Ni/Al2O3obtained by the method SDM according to example 2, in the reforming of methane at different feed ratios of H2O/CO2/CH4compared with the industrial activity of the catalyst is of forminga (G91-HGS, Süd-Chemie). Both catalyst contained similar amounts of Nickel: 16.6 wt.% NiO to Ni/Al2O3and 19 wt.% NiO in industrial catalysts. This catalyst also contains other promoters, such as K. the Catalytic tests were carried out on particles of 300-500 μm and obtained values of intrinsic activity. Activity apromotional catalyst Ni/Al2O3received by way of SDM, at 650°expressed as the mole fraction of the product (on dry basis), higher than the activity of modern industrial Ni-catalyst (Fig.9). Were obtained methane conversion 26% (SDM) and 23% (industrial). The activity of the catalyst SDM decreases with the increase of the relative content of CO2in the feed mixture (dry reforming). The industrial activity of the catalyst in a mixture of N2O/CO2/CH4=1/1/1 higher than that of the catalyst Ni/Al2O, obtained by the method of SDM. This may be due to the presence of promoters in the industrial catalyst, which reduces the rate of formation of coke, while the composition of the catalyst SDM was not present other metals than Ni.
The method of spray application allows you to obtain catalysts with homogeneous distribution of the active phase and uniform and controlled porosity with some regulation of pore size. Excellent characteristics of the catalysts obtained the s-SDM way, compared to other traditional methods (coprecipitation or impregnation) have been proven in various applications, including direct decomposition of N2O, ammonia oxidation and reforming of methane with water vapor.
1. The method of obtaining porous substances on the substrate for catalytic applications in which one or more soluble(x) predecessor(s) of the active metal phase is added to a suspension consisting of insoluble phase substrate in water or an organic solvent, the suspension is subjected to wet grinding to reduce particle size and phase of the substrate to less than 50 μm, add additives that facilitate processing before or after grinding, add a pore-forming substance and the suspension, the viscosity of which is supported at 100-5000 JV, is subjected to spray-dried, pressed and heat-treated to remove the pore-forming substance and bake.
2. The method according to claim 1, in which the particle size is reduced to 0.1-10 μm, preferably 1 μm.
3. The method according to claim 1, in which the viscosity of the suspension support at about 1000 SP.
4. The method according to claim 3, in which a pore-forming substance is removed at a pressure of 10-20 mbar O2diluted with an inert gas at 300 to 400°C.
5. The method according to claim 4, in which the heating rate is low, usually 1°·min-1.
6. The method according to claim 1, in which oterom phase substrate is one or more compounds selected from Al2O3, SiO2, ZrO2, TiO2, ZnO, MgO, MgAl2O4, CoAl2O4and CeO2.
7. The method according to claim 1, in which the active metal phase selected from transition metals such as Co, Ni, Cu, Fe, noble metals such as Pt, Rh, Ru, lanthanides such as La, CE, and other elements of the Periodic table, which can act as stabilizers and / or promoters - alkaline earth, such as Na, Mg, K, Cs, or other trivalent neustanovivshiesya metals such as Al, Ga.
8. The method according to claim 7, in which the precursor of the active phase is one or more compounds selected from acetates, nitrates, sulfates, oxalates, acetylacetonates, preferably acetates.
9. The method according to claim 1, which used a pore-forming substance is a cellulose, starch or polymer fibers.
10. The method according to claim 1, in which the additives that facilitate the processing, are dispersing agents, binders, plasticizers, lubricants, pH modifiers, etc.
11. The method of obtaining porous catalysts on the substrate for decomposition of N2O, in which the soluble precursor of cobalt is added to a suspension of cerium oxide and additives that treatment, in water, the suspension is milled to a particle size less than 10 microns, add a pore-forming substance, the viscosity of the reg is irout to about 1000 SP before as the suspension is subjected to spray-dried, followed by pressing, remove the pore-forming substance and the product is sintered.
12. The method according to claim 11, in which add zirconium oxide and/or a soluble compound of aluminum.
13. The method according to claim 11, in which the predecessor's use of cobalt acetate.
14. The use of the substance obtained according to any one of § § 11-13, as a catalyst for the decomposition of N2O.
15. The use of the substance obtained according to any one of claims 1 to 10, as a catalyst for the decomposition of N2O.
16. The use of the substance obtained according to any one of claims 1 to 10, as catalyst for the oxidation of ammonia.
17. The use of the substance obtained according to any one of claims 1 to 10, as a catalyst for the reforming of methane with water vapor.
SUBSTANCE: converter includes housing and devices for input oxygen enriched air, fed of vapour-hydrocarbon mix and bleeding of converted gas. The housing is provided with inner fikking designed as two cylindrical tubes installed one inside the other and forming with the converter housing two radial clearances: the outer clearance for input vapour-hydrocarbon mix and inner one for output of converted gas. At that the packing made of channeled plates is provided for inner fikking, this packing forms the channels of square section; the upper part (1/20-1/25) of channels is provided with perforation track, the middle part (1/5-1/6) of channels height located lower than perforation track is filled with catalyst used for primary and secondary hydrocarbon conversions; and the lowest part (1/6-1/8) of channels height is filled with catalyst used for preliminary hydrocarbon conversion. The device for input oxygen enriched air is positioned in the upper part of channels. The method is implemented in converter. Hydrocarbon material heating and converted gas cooling are carried out by the way of its passing through heat exchanger and mixing of hydrocarbon material with water vapour, then vapour-hydrocarbon mix is fed downstream through outer radial clearance and further it is delivered up the channels through catalyst bed for implementing of preliminary and primary conversions. Then through perforation track it is fed down the channels for converted gas oxidizing and secondary vapour conversion with subsequent converted gas upflow takeoff through inner radial clearance.
EFFECT: increasing of hydrocarbon material conversion and reduction of probability of free carbon formation.
2 cl, 3 dwg
SUBSTANCE: invention relates to two methods (two variants) of reforming process using oxidizing gas at temperature 980-1000°C. The recirculation of the flow part outgoing from the autothermic reformer to the flowrate vapour-hydrocarbon is described at that the said recirculation is implemented throught the instrumentality of thermocompressor ejector using heated beforehand supplied mix as operative fluid. For the optimization of general configuration the mole ratio of recirculating synthesis gas and operative fluid was chosen in the range 0.2-1.0. In order to prevent the carbon black formation in the reforming process recirculated hydrogen and vapour are fed to the input flow and the temperature of feeding is increased. Since there is a certain pressure drop between initial mixture of vapour and natural gas and the mix fed to reformer it is necessary to increase the pressure of initial mixture but it is compensated with the lower pressure drop in the heater and other equipment laid out upstream and downstream because of decreasing of vapour capacity.
EFFECT: reforming process is carried out without carbon black formation.
27 cl, 2 dwg, 1 tbl
FIELD: chemistry; processing of hydrocarbon material to synthesis gas.
SUBSTANCE: porous ceramic catalytical module represents the product of exothermic finely dispersed nickel-aluminium mixture exposed to vibration compaction and to sintering. The said product contains: nickel 55.93-96.31 Wt%; aluminium 3.69-44.07 Wt%. Porous ceramic catalytical module may contain up to 20 Wt% (based on the module weight) of titanium carbide as well as catalytic coating including following groups: La and MgO, or Ce and MgO, or La, Ce and MgO, or ZrO2, Y2O3 and MgO, or Pt and MgO, or W2O5 and MgO in quantity 0,002-6 Wt% based on the module weight synthesis gas is produced by conversion of methane and carbon dioxide mixture on porous ceramic catalytical module in filtration mode The process conditions are as follows: temperature 450-700°C, pressure 1-10 atm, rate of CH4-CO2 mixture delivery to catalytical module 500-5000 l/dm3*hr.
EFFECT: inventions permit to carry out the process at lower temperatures.
5 cl, 37 dwg
FIELD: hydrogen production processes.
SUBSTANCE: invention relates to catalysts for hydrolysis of hydride compounds to produce pure hydrogen for being supplied to power installations, including fuel cells. Invention provides catalyst for production of hydrogen from aqueous or water-alkali solutions of hydride compounds containing platinum group metal deposited on complex lithium-cobalt oxide and, additionally, modifying agent selected from series: titanium dioxide, carbon material, oxide of metal belonging to aluminum, magnesium, titanium, silicon, and vanadium subgroups. According to second variant, catalyst contains no platinum group metal. Described are also catalyst preparation method (variants) and hydrogen generation process, which is conducted at temperature no higher than 60°C both in continuous and in periodic mode. As hydrogen source, sodium borohydride, potassium borohydride, and ammine-borane can be used.
EFFECT: increased catalyst activity at environmental temperatures (from -20 to 60°C), prolonged time of stable operation of catalytic system, and reduced or suppressed platinum metals in composition of catalyst.
14 cl, 1 tbl, 20 ex
FIELD: method and torch for producing synthesis gas at decomposition of liquid hydrocarbons such as oil and natural gas at elevated temperatures without usage of catalyst by CO and hydrogen.
SUBSTANCE: method is realized by partial oxidation of liquid and solid combustible materials at presence of oxygen and oxygen containing gases. Fuel, oxygen-containing gas and atomizing fluid are fed to torch separately. Atomizing fluid is expanded just in front of inlet opening for fuel by means of one or several nozzles providing speed of atomizing fluid in range 20 - 300 m/s. Relation of diameter of outlet opening of nozzle for liquid fuel to diameter of opening of nozzle for atomizing fluid is in range 1/1.1 - 1/5.
EFFECT: possibility for simplifying process.
2 dwg, 2 ex
FIELD: method for producing synthetic gas, which may be used in oil chemistry for producing motor fuels.
SUBSTANCE: method includes processing of biogas under temperature of 1420-1800°C and following cooling of resulting synthetic gas. Thermal processing of biogas is performed in liquid heat carrier with ratio of volume of liquid heat carrier to volume of barbotaged gas, equal to 10-100 during 0,3-2 seconds, or in boiling layer of solid particles, where the speed of biogas is selected to be greater than minimal speed of fluidization.
EFFECT: increased purity of produced synthetic gas.
8 cl, 6 ex
FIELD: alternative fuels.
SUBSTANCE: invention relates to catalysts and process of steam conversion of hydrocarbons to produce synthesis gas. Proposed catalyst for steam conversion of hydrocarbons contains nickel oxide (4.0-9.2%) and magnesium oxide (4.0-6.5%) supported by porous metallic nickel (balancing amount). Carrier has specific surface area 0.10-0.20 m2/g, total pore volume 0.07-0.12 cm3/g, predominant pore radius 1-30 μm, and porosity at least 40%. Described are also catalyst preparation method and generation of synthesis gas via steam conversion of hydrocarbons.
EFFECT: increased heat conductivity of catalyst resulting in stable activity in synthesis gas generation process.
8 cl, 1 tbl, 5 ex
FIELD: production of synthesis-gas.
SUBSTANCE: proposed method is carried out at temperature of 750-900 C due to external heating of tubular furnace reaction tubes filled with catalyst; mixture of natural gas and superheated steam is fed to reaction tubes. External heating of reaction tubes filled with catalyst is first performed by burning the natural gas in air; after attaining the required mode of operation, external heating is carried out by burning the synthesis-gas fed from tubular furnace outlet to reaction tube external heating chamber. Device proposed for realization of this method includes tubular furnace with reaction tubes filled with catalyst, chamber for mixing the natural gas with superheated steam and external heating chamber for heating the reaction tubes filled with catalyst for maintenance of conversion process; heating chamber is provided with air inlet. Device is also provided with gas change-over point whose one inlet is used for delivery of natural gas fed to chamber of external heating tubular furnace reaction tubes during starting the mode of steam conversion process; other inlet of gas change-over point is used for delivery of synthesis-gas from tubular furnace outlet through distributing synthesis-gas delivery point. Device is also provided with regulator for control of delivery of synthesis-gas to reaction tube external heating chamber required for combustion.
EFFECT: enhanced economical efficiency of process.
3 cl, 1 dwg
FIELD: steam catalytic conversion of natural gas into synthesis-gas with the use of thermal and kinetic energy of synthesis-gas.
SUBSTANCE: proposed method includes external heating of reaction tubes of tubular furnace filled with nickel catalyst on aluminum oxide substrate by passing mixture of natural gas and superheated steam through them. External heating of reaction tubes filled with catalyst is performed by burning the natural gas in air at exhaust of flue gases from heating zone. After tubular furnace, the synthesis-gas is directed to gas turbine for utilization of thermal and kinetic energy; gas turbine rotates electric generator; then, synthesis-gas is directed to synthesis-gas burner of electric power and heat supply system; flue gases from external heating zone are directed to heat exchangers for preheating the natural gas and steam before supplying them to reaction tubes of tubular furnace. Device proposed for realization of this method includes sulfur cleaning unit, tubular furnace with reaction tubes filled with nickel catalyst on aluminum oxide substrate with inlet for gas mixture of natural gas and superheated steam; device also includes external heating zone for reaction tubes with flue gas outlet and gas burner for external heating of reaction tubes of tubular furnace with inlet for natural gas and air. For utilization of thermal and kinetic energy of synthesis-gas, device is provided with gas turbine and electric generator at tubular furnace outlet and synthesis-gas burner of electric power and heat supply system; device is also provided with heat exchangers for preheating the natural gas and steam before supplying them to tubular furnace.
EFFECT: improved ecological parameters; enhanced power efficiency of process.
3 cl, 1 dwg
FIELD: processing of hydrocarbon raw materials; oxidizing conversion of hydrocarbon gases into synthesis-gas.
SUBSTANCE: proposed method is carried out in flow-through two-chamber reactor in turbulent mode at combustion of mixture of hydrocarbon raw material and oxidizer. Superheated water steam is additionally introduced into said mixture in the amount of 5-20 mass-% relative to mass of carbon fed in form of hydrocarbon raw material. Three-component mixture is ignited in combustion chamber by jet of hot gas fed from external source where pressure exceeds pressure in first chamber during ignition. Combustion products from first chamber of reactor are directed to second chamber via nozzle at critical difference in pressure and combustion process is continued till content of oxygen in combustion products does not exceed 0.3 vol-%. Process is carried out in combustion reactor which is made in form of two coaxial cylindrical chambers with cooled nozzle located in between them; section of this nozzle ensures required pressure differential between chambers. Injector unit mounted at inlet of first chamber is used for delivery of working mixture components. Turbulator is mounted in first chamber. Lateral surface of first chamber has one or several holes for introducing the jet of hot gas from external source whose pressure exceeds pressure of first chamber and volume of second chamber exceeds that of first chamber. Proposed method makes it possible to produce synthesis-gas at H2/CO ratio approximately equal to 2.0; residual content of oxygen does not exceed 0.3 vol-% and content of carbon black does not exceed trace amount.
EFFECT: enhanced efficiency.
9 cl, 2 dwg, 11 ex
FIELD: inorganic synthesis catalysts.
SUBSTANCE: invention relates to catalytic elements including ceramic contact of regular honeycomb structure for heterogeneous high-temperature reactions, e.g. ammonia conversion, and can be used in production of nitric acid, hydrocyanic acid, and hydroxylamine sulfate. Described is catalytic element for heterogeneous high-temperature reactions comprising two-step catalytic system consisting of ceramic contact of regular honeycomb structure made in the form of at least one bed constituted by (i) separate prisms with honeycomb canals connected by side faces with gap and (ii) platinoid grids, ratio of diameter of unit honeycomb canal to diameter of wire, from which platinoid grids are made, being below 20.
EFFECT: increased degree of conversion and degree of trapping of platinum, and prolonged lifetime of grids.
5 cl, 6 ex
FIELD: inorganic synthesis catalysts.
SUBSTANCE: decomposition if N2O under Ostwald process conditions at 750-1000°C and pressure 0.9-15 bar is conducted on catalyst, which comprises (A) support composed of α-Al2O3, ZrO2, SeO2, or mixture thereof and (B) supported coating composed of rhodium or rhodium oxide, or mixed Pd-Rh catalyst. Apparatus wherein N2O is decomposed under Ostwald process conditions on the above-defined catalyst is also described. Catalyst is disposed successively downstream of catalyst grids in direction of stream of NH3 to be oxidized.
EFFECT: increased catalyst activity.
8 cl, 2 tbl, 3 ex
FIELD: chemical industry; methods of manufacture of the building structures.
SUBSTANCE: the invention is pertaining to the field of the chemical industry, in particular, to production of the nitric acid, nitric fertilizers, the cyanhydric acid, the nitrites and nitrates and to other productions of chemical products, where the flow sheet of production provides for the catalytic conversion of ammonia up to the nitrogen oxides with usage of the platinoid mesh catalytic agents. The platinoid mesh catalytic agent formed in the form of the catalytic package produced out of the layer-by-layer stacked wire catalytic meshes and weaved out of the wires with the diameter of 0.06-0.1 mm consisting of the alloys of platinum with rhodium, palladium, ruthenium and other metals of the platinum group differs that the catalytic package consists of two different in the geometry of the braiding types of the meshes sequentially alternating in the height of the package. At that the geometry of the braiding of the first type of the catalytic meshes is characterized by the number of the wires interlacing per 1 cm2 in the interval of 1024-450, and the geometry of the braiding of the second type of the catalytic meshes is characterized by the number of the wires interlacing per 1 cm2 in the interval of 400-200. The technical result of the invention is the increased conversion of ammonia and the decreased share of the platinoids included in the mesh catalytic agent production processes providing for the catalytic conversion of ammonia in the flow sheet of the chemical goods production.
EFFECT: the invention ensures the increased conversion of ammonia and the decreased share of the platinoids included in the mesh catalytic agent production processes providing for the catalytic conversion of ammonia in the flow sheet of the chemical goods production.
FIELD: chemical industry; method of intensification of the installations for production of the non-concentrated nitric acid.
SUBSTANCE: the invention is pertaining to the method of intensification of the installations for production of the non-concentrated nitric acid and may be used for raising productivity of the installations for production of the non-concentrated nitric acid under pressure. The invention provides for creation of the excess pressure on the inlet of the air compressor by preliminary compression of the atmospheric air in the high-pressure fan. At that the heat of the compression process in the warm season of the year is withdrawn by the direct contact with the water at the inlet of the fan, and in the cold season the heat is used for heating, at that in full or partially excluding heating of the air in the preheater mounted to prevent the icing up of the guiding apparatuses of the air compressor. At the enterprises with the high degree of the air dusting or chemical pollution for the contact cooling of the air by water it is possible to use scrubbers-washers, which combine the functions of the air cooler and the purification device. The method is effective for the operating installations, in which as a result of the wear-out of the flow-through section of the air compressors and the gas turbines decreases not only productivity, but also the pressure in the system, and as the result of it the concentration of the nitric acid. The method allows to realize the intensification of the installations using already existed equipment due to the increased pressure in the system. Concentration of the nitric acid is not lowered, the degree of purification of the tailing gases is preserved, production cost and the specific consumption of the steam and the natural gas are reduced.
EFFECT: the invention allows to realize the intensification of the installations using already existed equipment, to reduce production cost and the specific consumption of the steam and the natural gas.
4 cl, 2 ex, 2 tbl, 2 dwg
FIELD: methods and devices for supporting of the catalytic meshes in the burners for oxygenation of ammonia.
SUBSTANCE: the invention is pertaining to the support system for catalytic meshes in the burners for oxygenation of ammonia and to the method of reduction of movement of the particulates of the ceramic substance caused by the thermal expansion. The support system consists of the catalytic meshes (1) and possibly, of the support sieves (2) which are supported by the ceramic filling agents placed in the burner box with metallic walls and the perforated bottom. The support structure (9) is attached to the metallic wall (4) and-or the outer part of the periphery of the bottom (5). The technical result of the invention is development of the support structure, which does not cause damage of the packet from the catalyzer during operation of the burner, and the development of the system preventing movement of the of the particulates of the ceramic substance.
EFFECT: the invention ensures development of the support structure, which does not cause damage of the packet from the catalyzer during operation of the burner, and the development of the system preventing movement of the of the particulates of the ceramic substance.
12 cl, 2 dwg, 2 tbl
FIELD: inorganic compounds technologies.
SUBSTANCE: invention relates to ammonia conversion processes based on two-step catalytic system, which can be employed in production of nitric and hydrocyanic acids and in hydroxylamine sulfate production. Process according to invention comprises passing gaseous ammonia- and oxygen-containing mixture through two-step catalytic system, wherein first downstream step is embodied in a wire catalytic grate stack and second step in one or several layers of block honeycomb material, ratio of second-step hydraulic resistance value to the first-step one exceeding 4. Catalytic system steps are spaced from each other by distance equal to at most 10 and preferably 0.5 to 2 effective thickness of block channel σ calculated in terms of formula σ=2(S/(πn)1/2 (1-ε1/2), wherein S represents honeycomb block cross-section area, n number of channels in block, and ε open surface of block. Spacing between the steps is achieved by positioning between them spacing layer of gas-permeable chemically inactive material having hydraulic resistance coefficient below 100, hydraulic resistance of the second step being calculated as summary value of hydraulic resistances of honeycomb and spacing layers.
EFFECT: increased yield of desired products.
4 cl, 6 ex
FIELD: initiating ammonia conversion reaction.
SUBSTANCE: proposed method is performed on reticular platinoid catalyst by passing the ammonia-containing gas mixture and oxygen-containing gas through it; local sections of catalyst surfaces are periodically heated to reaction initiating temperature by means of linear electric heating elements located directly on catalyst surface. Equivalent diameters of local sections of catalyst surface are selected between 1-5 of magnitude of external equivalent diameter of separate electric heating element; linear electric heating elements are connected to electric power source at duty factor from 20 to 1 s. Used as material for reticular platinoid catalyst are the following alloys: Pt-81, Pd-15, Rh-3.5 and Ru-0.5 mass-%; Pt-92,5, Pd -4.0 and Rh -3.5 mass-%; Pt-95 and Rh-5 mass-%; Pt-92.5 and Rh-7.5 mass-%. Initiating the ammonia conversion reaction by this method is performed in reactors for production of nitric and hydrocyanic acids and hydroxylamine sulfate.
EFFECT: reduction of time required for reaction over entire surface of catalyst; reduction of explosion danger.
2 cl, 10 ex
FIELD: chemical industry.
SUBSTANCE: the invention is pertinent to the field of chemical industry, in particular to production of a catalysts and processes of oxidation of ammonia in production of a weak nitric acid. The invention offers an ammonia conversion catalyst on the basis of the mixture of oxides of unitized structure and a method oxidation of ammonia in production of weak nitric acid. The catalyst represents a mixture of oxides of the over-all formula (AxByO3Z)k (MmOn)f, (NwPgvOv)r where: A - cation of Ca, Sr, Ba, Mg, Be, Ln or their mixtures; B - cations of Mn, Fe, Ni, Co, Cr, Cu, V, A1 or their mixtures; x=0-2, y=1-2, z=0.8-l.7; M - A1, Si, Zr, Cr, Ln, Mn, Fe, Co, Cu, V, Ca, Sr, Ba, Mg, Be or their mixtures; m=l-3, n=l-2; N - Ti, Al, Si, Zr, Ca, Mg, Ln, W, Mo or their mixtures, P - phosphorus, O - oxygen; w=0-2, g=0-2, v=l-3; k, f and r - mass %, at a ratio (k+f)/r=0-l, f/r=0-l, k/f = 0-100. The catalyst is intended for use in a composition of a two-stage catalytic system generated by different methods, also in a set with the trapping platinoid screens and-or inert nozzles. The technical result ensures activity, selectivity and stability of the catalyst to thermocycles at its use in two-stage catalytic system with a decreased loading of platinoid screens.
EFFECT: the invention ensures high activity, selectivity and stability of the catalyst to thermocycles at its use in two-stage catalytic system with a decreased loading of platinoid screens.
8 cl, 1 tbl, 5 ex
FIELD: chemical industry; production of nitric acid.
SUBSTANCE: the invention is dealt with production of nitric acid with the help of oxidation of ammonia by oxygen of the air and absorption of nitrogen oxides by water in installations with uniform pressure at the stages of oxidation of ammonia and absorption of nitrogen oxides. The method of production of nitric acid in the installations with uniform pressure at the stages of oxidation of ammonia and absorption of nitrogen oxides provides, that compression of the air up to a uniform terminal pressure is conducted continuously within one stage without intermediate cooling and after that the compressed and so heated air is divided into two streams, one of which intended for production of nitric acid is directed to be cooled with further mixing with ammonia, and another is fed directly into a fuel combustion chamber connected with a recuperation turbine. The design embodiment of the installation for production of nitric acid provides for usage in the gas-turbine plant as an air engine for compression of air of an axial-flow compressor mounted directly on a common shaft with the recuperation turbine, at which near the outlet of the air engine the line of a compressed air stream is divided into two parts, one of which intended for production of nitric acid is first connected with a compressed air cooler and then with a mixer of ammonia with air, and the second intended for incineration of fuel is directly connected with the recuperation turbine combustion chamber. Besides in the capacity of a the compressed air cooler they use a "boiling" economizer connected to a line of a feed water for a boiler-utilizer and with a vapor collector of the boiler-utilizer by a line of steam-and-water mixture. The line of the air intended for production of nitric acid is also connected through the reheater of ammonia with a nitric acid blowing column. The technical result is simplification of the method, decreased investments and specific consumption of fuel.
EFFECT: the invention ensures simplification of the method, decreased investments and specific consumption of fuel.
4 cl, 1 dwg
SUBSTANCE: invention pertains to a catalyst and a method for selective increase in quality of paraffin raw material, with the aim of obtaining concentrated isoparaffin product as a benzine component. Description is given of the catalyst, which consists of a carrier from a sulphated oxide or hydroxide of group IVB (IUPAC 4) metals. The first component is, at least, from one lanthanide element or an yttric component, which is mainly ytterbium, and at least, one metal of the platinum group, which is mainly platinum, and a fireproof oxide binding substance, on which is dispersed at least, one metal of the platinum group. Description is given of the method of making the above mentioned catalyst, including a sulphated oxide or hydroxide of a group 1VB metal, depositing of the first component, mixing the sulphated carrier with the fireproof inorganic oxide of the oxide carrier, burning, depositing of the second component and subsequent burning. Description is given of the method of converting hydrocarbons through contacting with raw materials with the catalyst described above.
EFFECT: selective increase in quality of paraffin raw materials.
12 cl, 2 tbl, 2 dwg, 7 ex