A method of making the catalyst

 

(57) Abstract:

A method of manufacturing the catalyst comprises applying to the carrier layer of aluminum hydroxide from an aqueous solution of sodium hydroxide and sodium aluminate in the presence in the solution of aluminum metal, the Department specified media with a layer of aluminum hydroxide from the solution, the formation of the aluminum oxide layer by thermal dehydration of aluminum hydroxide, the introduction of known methods of one or more substances, "oven" aluminum oxide, one or more catalytic materials. The specified method of making the catalyst more efficient, and made the catalysts have a higher reproducibility of the quality of the layer and higher activity in the oxidation of CO and hydrocarbons. 3 C.p. f-crystals, 1 Il., 6 table.

The invention relates to the manufacture of catalysts for purification of exhaust gases of internal combustion engines.

A known method of manufacturing a catalyst, in which the layer of aluminum oxide formed on the surface of the carrier, such as cell structure, by dipping the carrier in the slurry of aluminum oxide or pumping through him of the suspension of the oxide of al is x components (patent SU 1170058, CL B 01 J 37/02, 30.07.85) [1]. To produce the desired amount of aluminum oxide on the carrier procedure of application of aluminum oxide in the slurry is repeated several times and after each procedure, surgery is drying, which leads to additional energy costs. In addition, in this method each time it is necessary before drying to remove excess slurry. For this cell structure dramatically shaken or blown off the channels of the honeycomb structure with compressed air. This leads to the inevitable loss of the suspension, which increases the flow of materials.

In U.S. patents[2]-[6] ([2]-U.S. patent 3227659, CL 252-437, priority 04.01.66, Phillips Petroleum Co. ; [3] the U.S. patent 3232520, CL 230-69, priority 01.02.66, Power Jetscresearch Development Limited; [4] the U.S. patent 3240698, CL 208-143, priority 15.03.66, Texac Inc.; [5] U.S. patent 3362783, CL 23-2, priority 09.01.68, Texac Inc.; [6] U.S. patent 4442024, class B 01 J 23/42, priority 09.02.82, Texac Inc.) describe the methods of preparation of catalysts in which the formation of aluminum oxide on the carrier is carried out by thermal dehydration layer of aluminum hydroxide formed on the carrier when contacting the carrier with a solution of hydroxide and sodium aluminate.

The closest way to the same destination to the claimed method is spatel layer of aluminum hydroxide from an aqueous solution of sodium hydroxide and sodium aluminate in the presence in the solution of aluminum metal, branch specified media with a layer of aluminum hydroxide from the solution, forming the aluminum oxide layer by thermal dehydration of aluminum hydroxide, the introduction of known methods of one or more substances, "oven" aluminum oxide, one or more catalytic materials. A method of manufacturing a catalyst, described in [7], is adopted for the prototype.

The disadvantage of this method is the length of the process applied on the carrier layer of aluminum hydroxide from an aqueous solution of sodium hydroxide and sodium aluminate and instability of this process, manifested in an unplayable receiving layer of aluminum hydroxide on the surface of the carrier of the required quality, which results in deterioration of the characteristics of the aluminum oxide layer, which is expressed in non-uniformity of the aluminum oxide layer on the carrier and a low adhesion layer of aluminum oxide to the surface of the carrier. In the operating conditions in the structure of the vehicle due to rapid temperature changes, vibration, and gas flow through the media will be the detachment and entrainment of the active layer, with a corresponding reduction in the efficiency of cleaning of exhaust gases.

The purpose of the crust is the target of sodium hydroxide and sodium aluminate and improving the quality of the resulting layer of aluminum oxide and characteristics of the catalyst as a whole.

This goal is achieved through the application of circulation of the solution of sodium hydroxide and sodium aluminate surface of the media.

Properties of aluminate solutions are well studied and described (Belyaev A. I. , "metallurgy of light metals", 1954, S. 42-47) [8]. The formation of aluminum hydroxide from a solution of hydroxide and sodium aluminate passes through two stages: the formation of embryos of aluminum hydroxide and further growth of the formed crystals. For forming a layer of aluminum hydroxide was uniformly throughout the surface of the carrier, you must ensure that at the stage of nucleation same degree of saturation of the solution of the sodium aluminate near the entire surface of the carrier and at the stage of crystal growth - the supply of reactants and the removal of reaction products.

This can be achieved through a diffusion process whose rate is low. In this case, the process of forming a layer of aluminum hydroxide on the surface of the carrier may take dozens of hours and becomes reproducible in time. Moreover, since the increase of the degree of saturation of a solution of the sodium aluminate by dissolving aluminum metal solution stanowienia can go both in the bulk solution near a metal of aluminum or directly on the surface of metal aluminum, where will be greater the degree of saturation and the surface layer of the solution near the phase boundary liquid-gas, where the evaporation temperature of the solution is lower than in the bulk of solution, and the degree of saturation is greater because of the lower solubility of sodium aluminate at a lower temperature. This leads to the further growth of crystals of aluminum hydroxide is in solution and subsequent precipitation. Therefore, the task of applying to the internal surface of the carrier complex geometric shapes, such as block carrier of honeycomb structure with a plurality of longitudinal channels with a length up to 200 mm and more, without the use of forced supply of reagents to the inner surface of the carrier and removal of reaction products from the surface, and thus ensuring the same degree of saturation of the solution of the sodium aluminate near the entire inner surface of the carrier, is practically difficult to implement. Forced supply of reagents to the inner surface of the carrier and the removal of reaction products from the surface of the carrier is carried out, organizing the flow of solution along the surface of the carrier, for example, using the nanos or ozonation of gas bubbles, which, podyma corrugated and flat strips of a thickness of 50 μm made of steel HU in the form of a cylinder with a diameter of 104 mm, height of 90 mm and a density of channels 90 pieces/cm2. Then the media is annealed at 900-1000oC for 20-20 PM

The solution of aluminate and sodium hydroxide is prepared as follows: in 1500 ml of distilled water is dissolved in 74 g of sodium hydroxide and add 50 grams of aluminum metal in the form of granules. Then the media hung on one of the levers measuring scales and placed in the solution so that the media was completely immersed in the solution, do not touch the bottom of the tank and was able to control the change of the mass media in time when planting on aluminum hydroxide. The media is removed from solution in the moment when aluminum metal is completely dissolved, and the increase in the mass media does not occur. At the time of extracting the carrier from the solution selected a sample solution for analysis on the content of sodium aluminate. Then the carrier is released from the solution, washed with distilled water, dried at 150oC and heated at 500oC for 1 h for the transformation of aluminum hydroxide to aluminum oxide. Then the media weigh, determine the utilization of aluminum, i.e., the proportion of aluminum metal deposited on a carrier in the form of aluminum oxide, from which xida aluminum.

Thus there was prepared 6 carriers. Data on time spent by medium in the solution, the utilization of aluminum, the degree of surface coverage are given in table. 1.

Example 2. At the bottom of the tank with a solution of hydroxide and sodium aluminate, prepared as in example 1, set the mixer with the special profile of the blades, which is driven by an alternating magnetic field and the rotation creates a flow of solution through the channels of the carrier from the bottom up. In order to avoid contact of metallic aluminum and a rotating stirrer, share their spatial mesh which is situated above the stirrer and on which is placed a metallic aluminum. The carrier is placed in a solution for forming a layer of aluminum hydroxide is removed from solution, select a sample solution for analysis, washed from sodium hydroxide in distilled water and subjected to heat treatment as in example 1. In order to avoid the influence of flow of solution through the media when operating the mixer to the operation of weighing, weighing the stirrer is turned off.

Thus there was prepared 6 carriers. Data on time spent by medium in the solution, the utilization of aluminum is aluminum, the degree of surface coverage of media and the utilization of aluminum in example 5 (table.2 ) is significantly higher compared with example 1 (table. 1).

Example 3. Hydroxide solution and sodium aluminate is prepared as in example 1. The media hung on the balance and immersed in the solution, as in example 1, and the bottom of the tank down through the air tube, which is bubbled through the solution so that the air bubbles rise to the top, passing through the channels of the carrier and carrying the solution, creating the flow of the solution through the channels along the surface of the carrier. In order to avoid the influence of flow of solution through the media on the operation of weighing, weighing the air supply is stopped. The media is removed from solution in the moment when aluminum metal is completely dissolved and the mass media does not occur. At the time of extracting the carrier from the solution selected a sample solution for analysis on the content of sodium aluminate.

Thus there was prepared 6 carriers. Data on time spent by medium in the solution, the utilization of aluminum, the degree of surface coverage are given in table. 3.

The reproducibility of the deposition of the aluminum oxide layer, the degree of the comparison example 1 (table. 1).

Example 4. A solution of sodium hydroxide and sodium aluminate is prepared as in example 1. For applying a layer of aluminum hydroxide use scheme, where the container hydroxide solution and the sodium aluminate and the media spatially separated, and the circulation of the solution is performed using a pump circuit capacity-medium-capacity, shown in the drawing.

Aluminum metal 2 is loaded into the container 1 with a solution of hydroxide and sodium aluminate. The pump 4 is realized by the circulation of the solution through the carrier 3 along the contour of the capacity-medium-capacity in the direction of the arrow. During the process of forming a layer of aluminum hydroxide periodically select a sample solution for analysis on the content of sodium aluminate. The process finishes when aluminum metal is completely dissolved and the content of sodium aluminate in the solution is equal to the content of sodium aluminate in examples 1-3, which corresponds to the complete solution of the hydrolysis of sodium aluminate.

Thus there was prepared 6 carriers. Data on time spent by medium in the solution, the utilization of aluminum, the degree of surface coverage are given in table. 4.

Vosproizvodimost INIA in example 4 (table. 4) is significantly higher compared with example 1 (table. 1).

Example 5-8. To test the adhesion of the aluminum oxide layer from the surface of the carrier samples coated with the layer of aluminum oxide are tested for thermal shock. To do this, use the media with a diameter of 2.5 cm and height 9 cm, obtained in the same manner as described in example 1.

The solution of aluminate and sodium hydroxide for each example is prepared by dissolving in 75 ml of distilled water, 3.6 g of sodium hydroxide and 2.4 g of aluminum metal in the form of granules.

Then, for each sample prepare 6 samples with a layer of aluminum oxide: without the use of circulation (example 5, samples 25-30); using circulation using a mixer as in example 2 (example 6, examples 31-36); using circulation during the bubbling of air, as in example 3 (example 7, samples 37-32); using flowing through the circuit by means of the pump when the tank solution and the carrier spatially separated, as in example 4 (example 8, the samples 43-48).

The samples are heated up to 800oC in a muffle furnace, then remove them and lowered into the water when 20-33oC. then dried at 150oC, weigh and calculate the loss of weight of aluminum oxide.

Lower losses of aluminum oxide when tested for thermal shock samples 31-48, made according to examples 6-8 indicate a stronger grip the aluminum oxide layer from the surface of the carrier, compared with 25-30 samples of example 5.

Examples 9-12. In examples 25, 28 (example 9), 33, 36 (10), 38, 42 (example 11), 43, 44 (example 12) in the same way consistently introduced by impregnation of BaO an aqueous solution of barium acetate and Pt from a solution of hexachloroplatinic acid. Samples are tested for activity in the oxidation of CO and hydrocarbons. As the hydrocarbon used propylene. The flow rate of the gas mixture 50000 h-1. The CO concentration is 1%, the concentration of the propylene - 0,06%. After testing the activity of the sample is weighed to determine the mass loss of the active layer due to exposure to high temperature and gas flow.

In table. 6 shows the data for the temperature fifty-fifty (T50) conversion and decrease of the mass.

Thus, the method of manufacturing a catalyst according to the present method more productive and catalysts produced by this method have a higher reproducibility of the quality of the layer, the better the quality CLASS="ptx2">

1. A method of manufacturing a catalyst comprising coating the carrier layer of aluminum hydroxide from an aqueous solution of sodium hydroxide and sodium aluminate in the presence in the solution of aluminum metal, the Department specified media with a layer of aluminum hydroxide from the solution, the formation of the aluminum oxide layer by thermal dehydration of aluminum hydroxide, the introduction of known methods of one or more substances, "oven" aluminum oxide, one or more catalytic substances, characterized in that the deposition of aluminum hydroxide is carried out, using the circulation hydroxide solution and sodium aluminate along the surface of the media.

2. The method according to p. 1, characterized in that the medium is immersed in a container with a solution of hydroxide and sodium aluminate, and the circulation is carried out by a special device.

3. The method according to p. 2, characterized in that the circulation is carried out using gas bubbles rising from the bottom up.

4. The method according to p. 1, characterized in that the container with the solution and the carrier spatially separated and circulation provide a special device in the closed circuit from the tank solution through novtel

 

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FIELD: hydrocarbon conversion catalysts.

SUBSTANCE: catalyst for generation of synthesis gas via catalytic conversion of hydrocarbons is a complex composite composed of ceramic matrix and, dispersed throughout the matrix, coarse particles of a material and their aggregates in amounts from 0.5 to 70% by weight. Catalyst comprises system of parallel and/or crossing channels. Dispersed material is selected from rare-earth and transition metal oxides, and mixtures thereof, metals and alloys thereof, period 4 metal carbides, and mixtures thereof, which differ from the matrix in what concerns both composition and structure. Preparation procedure comprises providing homogenous mass containing caking-able ceramic matrix material and material to be dispersed, appropriately shaping the mass, and heat treatment. Material to be dispersed are powders containing metallic aluminum. Homogenous mass is used for impregnation of fibrous and/or woven materials forming on caking system of parallel and/or perpendicularly crossing channels. Before heat treatment, shaped mass is preliminarily treated under hydrothermal conditions.

EFFECT: increased resistance of catalyst to thermal impacts with sufficiently high specific surface and activity retained.

4 cl, 1 tbl, 8 ex

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