Catalyst and method for producing dimethyl ether and methanol from synthesis gas

 

Catalyst for the synthesis of dimethyl ether and methanol from synthesis gas on the basis of copper-zinc-chromium-aluminum system, characterized in that it is prepared by mixing component A, obtained by treating aluminum hydroxide in the amount of 5-10 wt.% (in terms of aluminum oxide) by weight of the total solution chromic anhydride, component B, which represents ammonia or ammonium carbonate, or ammonium formity or ammonium acetate solution of copper and zinc, and component, which is used as the oxide or aluminum hydroxide; distillation of ammonia or ammonia and carbon dioxide from the solution; drying the obtained precipitate and calcination at a temperature not higher than 380^oC, and the operation of mixing the components a, B and C are conducted in such a way that either the first mixing components B and C, and further add the component a or first mixed components a and B, and the component In add later stage after drying or after the stage of calcination, and the operation of the distillation is carried out either after mixing all three components, or after mixing two components, one component B. the Technical result is to obtain a stable catalyst, providing a high prie years increased interest in obtaining dimethyl ether (DME) as an intermediate product for the production of motor fuel or in connection with the projected using it directly as an environmentally friendly fuel.

In industry, the synthesis of dimethyl ether by dehydration of methanol to high-silica zeolites. However, published a number of patents on the catalytic synthesis of dimethyl ether from carbon oxides and hydrogen, in some cases with the addition of water vapor.

The process of DME synthesis involves the reaction of hydrogenation of oxides of carbon to methanol, the conversion of carbon monoxide with water vapor and dehydration of methanol to DME. To implement such a process is necessary catalysts possessing multifunctional properties, which must ensure the flow of all these reactions.

In known patents indicated on the application for the purpose of alumina and catalysts for methanol synthesis.

As catalysts are used, as a rule, copper-zinc-chromium, copper-zinc-chromium-aluminum or copper-zinc-chromium-aluminosilicate system.

In all cases, the catalysts obtained by coprecipitation of the components of the nitric acid solutions followed by washing precipitation, drying, calcination and pelletizing, separate deposition hydrogenating and dehydrating components and their subsequent mixing (U.S. Pat. Germany 3118620) or using them separately, by C is utilizator (U.S. Pat. Italy 929006). The catalyst consists of carbonates (basic carbonates and/or hydroxides of the metals, which in the subsequent calcining turn into oxides (mixed oxides).

In addition to these disadvantages of the above methods, as significant production costs associated with the consumption of pure condensate or demineralized water for washing precipitation, difficulties in further processing of the filtrate and use of wash water containing impurities of non-ferrous metals, obtained by using these methods, the catalysts have insufficient stability in the synthesis of dimethyl ether, and must be regenerated directly in the synthesis process after a short period of time (40-60 hours), which complicates the process, reduce production and additional costs (U.S. Pat. USA 2097382 and Germany 3118620).

Closest to the proposed catalyst is a copper-zinc-chromium-aluminum catalyst, obtained by the Japan patent 5071297 B4. The catalyst is prepared by joint precipitation of zinc and chromium and/or aluminum with obtaining sediment and deposition of copper and zinc with chromium and/or aluminum with obtaining sediment B. Precipitation a and B together is dispersed in water, then subspecialise high performance in the process of synthesis of dimethyl ether (DME) and methanol in a long time.

This goal is achieved by the fact that to obtain a catalyst using the following components: component A, obtained by treating aluminum hydroxide in the amount of 5-10 wt.% (in terms of aluminum oxide) of the total mass of the final calcined catalyst with a solution of chromic anhydride; component B represents ammonia or ammonium carbonate, or ammonium formity or ammonium acetate solution of copper and zinc; - component, which is used as the oxide or hydroxide of aluminum, preferably in the form of powder or aqueous suspension 1:1, and the catalyst obtained by the operations of mixing the above components, distillation of ammonia or ammonia and carbon dioxide from the solution at a temperature of 80-90^oWith, drying the obtained precipitate to a fluid state and its calcination at a temperature not higher than 380^oC, and the mixture of components a, B and C are conducted sequentially in the following way: first or mix components a and B, and the component To add later, or first mixing components B and C, and further add component a, and, thus, in the case where first by mixing the components a and B, the component To add to the intermediate PSEH three components, or after mixing two components, one of which is a component B.

Collected in this way the catalyst for the synthesis of dimethyl ether and methanol is a copper-zinc-chromium-aluminium-containing catalyst, preferably of the following composition (in wt. %): SiO - (17,5-35,0); ZnO - (17,5-35,0); CR₂O₃- (12,5-25,0); Al₂O₃- (5-52,5) (the content of the components is given in terms of the content of oxides in the calcined catalyst), including at least 10 wt.% by weight of calcined catalyst aluminum compounds with chromium and at least 10 wt. % of chromium compounds with copper and zinc (total).

Thus, the proposed method for the preparation of the catalyst provides a high content of chromium and aluminum in the catalyst, and the presence in its composition more stable, not destroyed in the process of synthesis of dimethyl ether and methanol components, preferably of chromium, copper and zinc (CuZn)Cr₂O₄and hidrocarbonetos aluminum Al(Oh)CDF₄.

The calcined catalyst containing all three components a, B and C, may be further treated with a solution of copper salt, preferably based introduction 2-9% CuO on the calcined catalyst, and then subjected to drying and p. the present invention is that: - does not require consumption of reagent-precipitator, for example PA₂CO₃; - there is no need to wash sediments. Accordingly, no additional equipment is required for processing of the filtrate in a saleable by-product and equipment for cleaning and recycling the wash water.

Recovery of ammonia and carbon dioxide is carried water, i.e., the most simple compared to other methods of cleaning; resulting ammonium or amino-carbonate solutions are put back into the production cycle.

Obtaining a catalyst according to the present invention is illustrated further by the examples, without ogranichivayas character.

Examples of preparation of the catalyst.

Example 1.

The receiving component A.

Dissolved in 150 ml of N₂About 33 g of chromic anhydride. Add in a solution of 15 g of milled aluminum hydroxide (fraction 0-0,06 mm), stirred at 50-70^oC for 4-6 hours

The receiving component B.

1. Dissolved 28 g of copper in 250 ml of an ammonium carbonate solution containing 200 g/l NH₃and 150 g/l CO₂at a temperature of 50-70^oC.

2. Dissolved 28 g of zinc in 200 ml of an ammonium carbonate solution containing 200 g/l NH₃and 150 g/l CO₂at a temperature of 50-70o

The mixture of components.

In the resulting solution component B add component b and mix. Then add the component And raise the temperature in the solution to 90^oAnd distilled ammonia (to a residual content of 5 g/l) and carbon dioxide. The formed precipitate is filtered, dried at 100-120^oWith up to a friable state, mixed, calcined at a temperature of not higher than 380^oWith (continue roasting until then, until the weight of the sample, optionally calcined at 900^oWith, will not be less than its weight after calcination at 380^oWith 5-6%) and tabletirujut.

The composition of the catalyst after calcination in terms of oxides: CuO - 30,5, ZnO - 30,5, CR₂O₃- 22, Al₂About₃- 17 wt.%.

In all subsequent examples, the receive operation of the components a and B, distillation of ammonia or ammonia and carbon dioxide, drying the obtained precipitate and calcination is conducted in the same manner as described in example 1.

Example 2.

Component In the aluminum hydroxide powder in the amount of 15,

The mixture of components.

In contrast to example 1, after mixing components B and In effect the Stripping of ammonia and carbonic acid, the precipitate is filtered, mixed with component a, dried and calcined as described in note the sub>O₃- 17 wt.%.

Examples 3 and 4.

Blending operation and subsequent operations are similar to examples 1 and 2, respectively.

The difference lies in the fact that the component is added to the number 70,

The composition of the catalyst after calcination in terms of oxides: CuO - 23,25, ZnO - 23,25, CR₂O₃- 16,6, Al₂About₃- 36.9 wt.%.

Example 5.

Component In the alumina powder in the amount of 46,

The mixture of components.

First mix the components a and B, distilled ammonia and carbonic acid, the precipitate is filtered and dried as described in example 1, and then add the component In and calcined as described in example 1.

The composition of the catalyst after calcination in terms of oxides: CuO - 23,25, ZnO - 23,25, CR₂O₃- 16,6, Al₂About₃- 36.9 wt.%.

Example 6.

Component as in example 5.

The mixture of components.

First mix the components a and B, distilled ammonia and carbonic acid, the precipitate is filtered off, dried and calcined as described in example 1, and then add the component Century.

The composition of the catalyst after calcination in terms of oxides: CuO - 23,25, ZnO - 23,25, CR₂About₃- 16,6, Al₂About₃- 36.9 wt.%.

Example 7.

Component as in example 5.

Mesenerskie introduction 2-9% CuO (calcined catalyst), with subsequent drying and calcination at a temperature not higher than 380^oC.

Another embodiment of the present invention to implement its purpose, is a method of obtaining DME and methanol from synthesis gas at elevated temperature and pressure, which use the above-described catalysts.

The following examples illustrate the advantages which are achieved with the use of catalysts according to the present invention, in the method of synthesis of dimethyl ether and methanol.

In more detail, in table.1 given process conditions for the synthesis of a mixture of DME and methanol on the catalyst prepared according to certain examples of the present application, and presents data on their activity (conversion) and selectivity in the process. In table.2 shows the results for the catalyst prepared according to example 6, obtained at different points in time during its continuous operation for 450 hours in different modes.

Testing of the catalysts (table.1, 2) was performed in a flow reactor.

In the first column of the table.1 are numbers of examples, which were obtained from the studied catalysts. In the first column of the table.2 shows the number of experiments in the order of their conduct.

In the second column Enola; in the third column is the volumetric feed rate of the original synthesis gas, then (columns 4, 5 and 6-9) - the pressure in the reactor, the temperature and the composition of the primary synthesis gas, respectively. In column 10 of table.1 shows the conversion of carbon monoxide in percent, and in columns 11 and 12 - selectivity for dimethyl ether and methanol, respectively. In column 10 of table.2 shows the performance of the catalyst for dimethyl ether (kg DME per 1 liter of catalyst per hour). In column 11 of table.2 given the concentration of dimethyl ether in volume percent at the outlet of the catalyst layer, in the column 12 - the conversion of carbon monoxide in percentages in columns 13 and 14 - selectivity for dimethyl ether and methanol.

As can be seen from the table.1 and 2, the use of the inventive catalysts provides high conversion of carbon monoxide in a flow reactor. However, depending on the conditions of mixing of components a, B, C can be obtained at the output of a mixture of methanol and dimethyl ether with different selectivity for dimethyl ether and methanol.

From table. 2 can also be seen when comparing the synthesis of DME on prepared according to example 6 catalyst at different points in time, after 400 h of operation catalyst performance for dimethyl ether is not izmenenii of carbon monoxide in the feed gas experience 6 (45,6% vol. from 39.3% vol. in experiment 1). On the stable operation of the catalyst also shows the performance of the process of synthesis of DME for experiments 5 (350 h) and 6 (450 hours of operation catalyst).

It should also be noted that, as follows from the data table.2, the catalyst has high stability and high activity. Thus, the conversion of carbon monoxide in the flow reactor is already at a pressure of 5.4 MPa reaches 70,3% (example 2). When the pressure 10.9 MPa and flow rate 5490^-1the conversion of carbon monoxide per pass is to 87.9% in performance dimethyl ether 0,98 kg DME/l cat-RA/h (example 3).

Thus, the test results showed that the proposed catalyst for 450 h practically does not lose its activity and selectivity with respect to the synthesis of DME (PL.2). At the same time, in the process of the prior art regeneration of the catalyst have to spend 40-60 hours, preferably daily (U.S. Pat. USA 2097382 and U.S. Pat. Germany 3118620), i.e. about one order of magnitude shorter periods of time.

While the increase in flow rate to 10000 h^-1at the optimum temperature (260^oC) and a pressure of 9.8 MPa is achieved extremely high performance catalyst for DME - 1,65 kg/l/h, with the degree pet the best indicators of the patented process. In particular, for comparison, you can specify that the achieved performance of methanol according to the generally accepted at the present time in the world of technology at the close pressure of 8 MPa is 0.4 kg/kg/h, while the proposed catalyst in terms of produced methanol she is more than 2 kg/l/h (or 2 kg/kg/h, taking into account the fact that the density of the catalyst according to the invention is close to 1).

Furthermore, an additional advantage of the method of synthesis of dimethyl ether and methanol according to the present invention lies in the fact that you can use synthesis gas of arbitrary composition. The proposed catalysts can recycle synthesis gas, containing up to 70% nitrogen, obtained by air oxidation of methane, with a high conversion per pass - over 70% (almost to the equilibrium). An example is given in table.3 for the catalyst according to example 6 (notations are the same as in table.1, 2). In contrast, the described known processes are carried out with the use of synthesis gas, almost not diluted with nitrogen.

Claims

1. Catalyst for the synthesis of dimethyl ether and methanol from synthesis gas on the basis of copper-zinc-chromium-aluminum system, characterized in that it prigotovlena alumina by weight of the total solution chromic anhydride, component B, which represents ammonia or ammonium carbonate, or ammonium formity or ammonium acetate solution of copper and zinc, and component, which is used as the oxide or aluminum hydroxide; distillation of ammonia or ammonia and carbon dioxide from the solution; drying the resulting sludge; and annealing at a temperature not higher than 380°C, and the operation of mixing the components a, B and C are conducted in such a way that either the first mixing components B and C, and further add the component a or first mixed components a and B, component b is added later stage after drying or after the stage of calcination, and the operation of the distillation is carried out either after mixing all three components, or after mixing two components, one component B.

2. The catalyst p. 1, wherein after calcination of the mixture components obtained product is further treated with a solution of copper, and then again dried and calcined.

3. The way dimethyl ether and methanol from synthesis gas in the presence of copper-zinc-chromium-aluminum catalyst at elevated pressure and temperature, characterized in that the use of the catalyst according to any one of paragraphs.1 and 2.

4. The method according to p. 3, distinguish