CN101844083A - Monolithic catalysts used for preparing dimethyl ether by using synthesis gas, preparation method and application - Google Patents

Abstract

A monolithic catalyst for the production of dimethyl ether from synthesis gas, with honeycomb ceramics as the carrier, γ-Al ₂ O ₃ as the inert component coating, and the loading of the inert component in each gram of the monolithic catalyst is 0.2-0.5g ;CuO-ZnO-Al ₂ O ₃ /SO ₄ ² -γ-Al ₂ O ₃ is the active component, loaded on the inert component coating, and the active component loading per gram of monolithic catalyst is 0.6-2.0g . The invention also provides the preparation method and application of the above catalyst. The monolithic catalyst prepared by the invention has excellent heat and mass transfer performance, easy to scale up, mild reaction conditions, high catalytic activity, good stability, less by-products, and more importantly, it solves the problem of high reaction temperature in the prior art , The problem of poor catalyst stability.

Description

A monolithic catalyst for producing dimethyl ether from synthesis gas, its preparation method and application

technical field

The invention relates to a monolithic catalyst for directly preparing dimethyl ether from synthesis gas.

The present invention also relates to the preparation method of above-mentioned catalyst,

The invention also relates to the use of the catalysts described above.

Background technique

Dimethyl ether is an important chemical raw material, which is widely used in the fields of pharmaceuticals, fuels, pesticides, refrigeration, daily chemicals, etc. It has the characteristics of non-toxic, safe, high combustion heat efficiency, clean combustion tail gas without black smoke, and no corrosion to metals, etc. Advantages, it can be used as propellant, civil fuel and diesel engine fuel, etc. It is an ideal substitute for liquefied fuel gas; it is also an important intermediate for producing liquid fuel from natural gas and coal, and plays a very important role in modern chemical production. Therefore, It has attracted increasing attention at home and abroad.

The traditional industrial method for preparing dimethyl ether is the dehydration reaction of methanol carried out on a solid acid catalyst. Such as Chinese patents CN 1613558A, CN 1745894A, CN 1106219C, CN1895779A, CN 1919451A, CN 1151110C and U.S. patents US707606, US4560807, etc. have all reported the catalyst progress of methanol dehydration to dimethyl ether from different angles, but there are certain differences Defects, or the reaction temperature is high, which is unfavorable to the stability of the catalyst; or the preparation process is complicated; or the modification component contains rare earth elements or precious metals, and the cost is relatively high.

In recent years, the development of a new process for directly producing dimethyl ether from synthesis gas has attracted more and more attention from researchers. There are methanol synthesis and methanol dehydration reactions in the synthesis gas direct synthesis of dimethyl ether reaction system, so the catalyst used is a bifunctional catalyst composed of a methanol synthesis catalyst and a methanol dehydration catalyst. Methanol synthesis catalysts are mainly copper and zinc-based composite metal oxide catalysts, such as Cu-Zn-Al, Cu-Zn-Zr or Cu-Zn-Cr composite oxides; methanol dehydration catalysts mainly use γ-Al ₂ O ₃ or Solid acid catalysts such as molecular sieves. Patents US5753716, US 4417000, ZL 00133279.1, ZL 93115774.9, CN 101157038A, etc. have used different bifunctional catalysts to study the reaction process of syngas directly producing dimethyl ether, but the bifunctional catalysts disclosed in these invention patents have reaction temperature and reaction There are defects such as high pressure and low catalytic activity, and most patents do not mention the service life of the catalyst. Most of the bifunctional catalysts for the synthesis of dimethyl ether are granular, and the bed pressure drop of the packed reactor of the granular catalyst is usually large, there is a large temperature gradient between the beds, and the thermal resistance is relatively high. Large and poor thermal conductivity, it is very easy to cause local overheating of the catalyst bed, so that the active components are easier to sinter during the reaction process, and the activity of the catalyst decreases rapidly. How to improve the activity and stability of the catalyst for direct synthesis of dimethyl ether from synthesis gas is the key issue in the one-step synthesis of dimethyl ether, and to obtain a high CO conversion rate for the direct production of dimethyl ether from synthesis gas under mild reaction conditions Catalysts with longer service life are the main target direction.

Contents of the invention

The object of the present invention is to provide a monolithic catalyst for directly preparing dimethyl ether from synthesis gas with lower reaction temperature, higher CO conversion rate and dimethyl ether selectivity.

Another object of the present invention is to provide a method for preparing the above-mentioned monolithic catalyst.

The invention expects to solve the problems of high reaction temperature, low catalyst activity and poor stability existing in the prior art.

In order to achieve the above object, the monolithic catalyst for synthesis gas to dimethyl ether provided by the present invention is expressed as CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ /honeycomb ceramic; honeycomb Ceramic is the carrier, γ-Al ₂ O ₃ is the inert component coating, and the load of the inert component per gram of monolithic catalyst is 0.2-0.5g, preferably 0.3-0.4g; CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ is the active component, which is loaded on the inert component coating, and the loading amount of the active component per gram of monolithic catalyst is 0.6-2.0g, preferably 1-1.4g.

In the monolithic catalyst for producing dimethyl ether from synthesis gas, the pore density of the honeycomb ceramic carrier is 200-400 pore/square inch.

The method for preparing the above-mentioned monolithic catalyst provided by the present invention, the main steps are:

1) Preparation of honeycomb ceramic carrier loaded with γ-Al ₂ O ₃ coating: immerse the honeycomb ceramic carrier in the aluminum sol, rinse the aluminum sol on the surface after taking it out, blow out the residual aluminum sol in the channels of the honeycomb ceramic carrier, dry and roast The honeycomb ceramic carrier loaded with γ-Al ₂ O ₃ coating is obtained;

2) Preparation of CuO-ZnO-Al ₂ O ₃ methanol synthesis catalyst by co-precipitation method: the nitrate mixed solution of copper, zinc and aluminum and sodium carbonate solution are mixed under the conditions of temperature 50-80°C and pH=6.0-10.0 flow co-precipitation, the resulting precipitation solution is aged at 60-90 ° C, dried and roasted to obtain CuO-ZnO-Al ₂ O ₃ powder, wherein the mass ratio of copper, zinc and aluminum in the nitrate mixed solution is 15-65:10 -40: 2-20;

3) Preparation of SO ₄ ^2- -γ-Al ₂ O ₃ : γ-Al ₂ O ₃ is calcined at 400°C-500°C and then refluxed with acid or salt solution containing SO ₄ ^2- at 50-90°C , to obtain a solid sample by filtering, drying and roasting the obtained solid sample to obtain SO ₄ ^2- -γ-Al ₂ O ₃ , wherein the mass content of SO ₄ ^2- is 1-20%;

4) Preparation of CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ slurry: mix CuO-ZnO-Al ₂ O ₃ in step 2 with SO ₄ ^2- -γ- in step 3 Al ₂ O ₃ is mechanically mixed according to the mass ratio of 1:1-4:1 and then added with water or ethanol for ball milling, wherein the mass ratio of water or ethanol to SO ₄ ^2- -γ-Al ₂ O ₃ is 12-20 : 1, to obtain CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ slurry;

5) Monolith catalyst preparation: impregnate the honeycomb ceramic carrier loaded with γ-Al ₂ O ₃ coating in step 1 into the CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O in step 4 ₃ In the slurry, after taking it out, rinse the slurry on the surface of the carrier, blow out the residual slurry in the carrier channel, and then flash dry at 250-300°C to obtain CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ /honeycomb ceramic monolithic catalyst.

The preparation method, wherein, before step 1, soak the honeycomb ceramic carrier with _HNO3 with a mass concentration of 30-65%, take it out, wash it with water to pH=7.0, dry it at 100-120°C for 10-24 hours (h), and bake at a temperature of 450-550°C, roasting time 2-6h.

The preparation method, wherein the solid content of the aluminum sol in step 1 is 8-15wt%, the drying temperature is 100-120°C, the drying time is 10-24h, the calcination temperature is 450-550°C, and the calcination time is 2-6h.

Said preparation method, wherein the co-precipitation temperature in step 2 is 60-70°C, pH=7.0-9.0, and the aging time is 1-3 hours.

Said preparation method, wherein, the mass ratio of copper, zinc and aluminum contained in the nitrate mixed solution described in step 2 is 25-50:15-30:5-10.

The preparation method, wherein the acid or salt containing SO ₄ ^2- in step 3 is H ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ , ZnSO ₄ , FeSO ₄ , (NH ₄ ) ₂ SO ₄ , Ti (SO ₄ ) ₂ or mixtures thereof.

The preparation method, wherein, the mass content of SO ₄ ^2- in the SO ₄ ^2- -γ-Al ₂ O ₃ prepared in step 3 is 1-15%.

The preparation method, wherein, in step 3, the reflux temperature of SO ₄ ^2- treated γ-Al ₂ O ₃ is 60-80°C, and the reflux time is 24-72h.

Said preparation method, wherein, in step 3, the drying temperature is 90-120° C. for 12-48 hours; the calcination temperature is 400-700° C. for 3-8 hours.

The preparation method, wherein, in step 4, the mass ratio of CuO-ZnO-Al ₂ O ₃ to SO ₄ ^2- -γ-Al ₂ O ₃ is 2:1-3:1, water or ethanol and SO ₄ ^{2 -} The mass ratio of -γ-Al ₂ O ₃ is 15-18:1, the rotational speed of the ball mill is 220-250r/min, and the ball milling time is 3-4h.

Said preparation method, wherein, the monolithic catalyst in step 5 is flash-dried in a muffle furnace, the drying temperature is 270-280° C., and the drying time is 5-12 minutes.

Said preparation method, wherein, the soaking and flash drying process in step 5 is repeated.

The CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ /honeycomb ceramic monolithic catalyst of the present invention can be applied in the synthesis gas dimethyl ether reaction, and the catalyst is loaded in a fixed-bed reactor , reduce _{the H2} diluted with N2 at normal pressure at 250-280°C and the space velocity of 1000-3000h ^-1 , after cooling down to 80-100°C, switch the _H2 diluted with _N2 into synthesis gas, and proceed with heating Synthesis reaction, _the synthesis reaction conditions are: temperature 200-280°C, pressure 1-10MPa, space velocity 500-10000h ^-1 ; wherein, the volume ratio of H ₂ diluted with N 2 is N ₂ : H ₂ =10-20: 1; The volume composition of the synthesis gas is: H ₂ :CO:CO ₂ =2:1-2:0.1-2.

The honeycomb ceramic integral catalyst provided by the present invention dilutes the boundary between the catalyst and the reactor, adopts a special design different from traditional catalysts, and can conveniently integrate various chemical operations such as chemical reaction, separation, heat exchange, and mass transfer. Together. On the other hand, thanks to the special geometrical, structural, and hydrodynamic properties, the monolithic catalyst exhibits excellent mass and heat transfer performance and is easy to scale up. The reaction test of the direct synthesis of dimethyl ether from synthesis gas in a fixed bed reactor shows that the monolithic catalyst of the present invention has the advantages of low reaction temperature, high catalytic activity and stable catalytic performance. The monolithic catalyst prepared by the method of the invention is suitable for synthesizing dimethyl ether from synthesis gas from various sources such as coal, natural gas and biomass.

Description of drawings

Fig. 1 is the stability evaluation experiment result of the catalyst 100h prepared in embodiment 2.

Detailed ways

The invention relates to a synthesis of honeycomb ceramics as a carrier, γ-Al ₂ O ₃ as an inert component coating, and CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ as an active component Preparation and application of a monolithic catalyst for the direct production of dimethyl ether from gas.

The technical scheme that the present invention adopts is as follows:

(1) Preparation of catalyst

The preparation method of the monolithic catalyst directly preparing dimethyl ether from synthesis gas provided by the invention comprises the following steps successively:

①Treatment of honeycomb ceramic carrier: Soak the honeycomb ceramic carrier with a size of 12×12×50mm in HNO ₃ with a mass concentration of 30-65% for 1-4h, take it out and wash it with deionized water until PH=7.0, dry and roast it to obtain Honeycomb ceramic substrate treated with _HNO3 ;

② Preparation of honeycomb ceramic carrier loaded with γ-Al ₂ O ₃ coating: immerse the HNO _3- treated honeycomb ceramic carrier obtained in step ① into 50ml of aluminum sol with a solid content of 5-20wt%, and put it into a vacuum oven for pumping When the liquid level of the glue rises to close to the mouth of the beaker, stop vacuuming, take it out after 30s, rinse the aluminum sol on the surface with deionized water, blow out the remaining glue in the channel with 0.2-0.7MPa compressed air, and dry and roast After that, the honeycomb ceramic carrier loaded with γ-Al ₂ O ₃ coating is obtained;

③ Preparation of CuO-ZnO-Al ₂ O ₃ Methanol Synthesis Catalyst by Co-precipitation Method: Co-flow the nitrate mixed solution of copper, zinc and aluminum and sodium carbonate solution at a temperature of 50-80°C and a pH of 6.0-10.0 Co-precipitation, the resulting precipitation solution is aged at 60-90°C for 1-4h, and after suction filtration, washing, drying, and roasting, CuO-ZnO-Al ₂ O ₃ powder is obtained, in which copper, zinc, and aluminum in the nitrate mixed solution The mass ratio is 15-65: 10-40: 2-20;

④ Preparation of SO ₄ ^2- -γ-Al ₂ O ₃ : Commercial γ-Al ₂ O ₃ is roasted at 400°C-500°C and then refluxed with acid or salt solution containing SO ₄ ^2- at 50-90°C for 12 -72h, then filter to obtain a solid sample, wash, dry and roast the obtained solid sample to obtain SO ₄ ^2- -γ-Al ₂ O ₃ , wherein the mass content of SO ₄ ^2- is 1-20%;

⑤ Preparation of CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ slurry: combine CuO-ZnO-Al ₂ O ₃ in step ③ with SO ₄ ^2- -γ-Al ₂ in step ④ O ₃ is mechanically mixed according to the ratio of 1:1-4:1 in mass ratio, then put into a 250ml ceramic ball mill jar, add water or ethanol, and ball mill for 2-6h at a speed of 200-280r/min in the ball mill, wherein water or The mass ratio of ethanol to SO ₄ ^2- -γ-Al ₂ O ₃ is 12-20:1 to obtain CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ slurry;

⑥Monolithic catalyst preparation: impregnate the honeycomb ceramic carrier loaded with γ-Al ₂ O ₃ coating in step ② into the CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ slurry in step ⑤ Put it in a vacuum oven until air bubbles emerge from the honeycomb ceramic channels, stop vacuuming, take it out after 30s, rinse the slurry on the surface of the carrier with water, blow out the residual slurry in the channels with compressed air, and place it in a muffle furnace Flash drying at 250-300°C for 2-15min. Repeat this impregnation _and flash drying process 3-10 times to obtain CuO-ZnO-Al 2 O ₃ /SO with a loading of active components of 0.6-2.0 g and a loading of γ-Al ₂ O ₃ of 0.2-0.5 g ₄ ^2- -γ-Al ₂ O ₃ /honeycomb ceramic monolithic catalyst finished product.

(2) Use of catalyst

The monolithic catalyst is packed in a stainless steel pressurized fixed-bed reactor with an inner diameter of 10mm by wrapping it with a sealing ring. _H2 diluted with _N2 under normal pressure is reduced for 6-8h under the conditions of 250-280°C and space velocity of 1000-3000h ^-1 , and the _H2 diluted with _N2 is switched to high-pressure syngas after cooling down to 80-100°C. Then the synthesis reaction is carried out by raising the temperature program, the reaction conditions are: temperature 200-280°C, pressure 1-10MPa, space velocity 500-10000h ^-1 .

In the above technical solution, the mass concentration of the _HNO3 solution described in step ① is preferably 50-65%, and the soaking time is preferably 2-3h.

In the above technical solution, the drying temperature in step ① is preferably 100-120°C, the drying time is preferably 10-24h, the calcination temperature is preferably 450-550°C, and the calcination time is preferably 2-6h.

In the above technical solution, the solid content of the aluminum sol described in step ② is preferably 8-15wt%, the drying temperature is preferably 100-120°C, the drying time is preferably 12-20h, the calcination temperature is preferably 450-550°C, and the calcination time is preferably 3 -5h.

The mass ratio of copper, zinc and aluminum in the nitrate mixed solution described in step ③ in the above technical solution is preferably 25-50:15-30:5-10.

In the above technical solution, the co-precipitation temperature in step ③ is preferably 60-70°C, the pH value is preferably =7.0-9.0, and the aging time is preferably 1-3h.

In the above technical solution, the mass percentage of SO ₄ ^2- in the SO ₄ ^2- -γ-Al ₂ O ₃ described in step ④ is preferably 5-15%.

In the above technical scheme, the acid or salt containing SO ₄ ^2- described in step ④ is preferably H ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ , ZnSO ₄ , FeSO ₄ , (NH ₄ ) ₂ SO ₄ , Ti (SO ₄ ) ₂ or a mixture thereof, more preferably Al ₂ (SO ₄ ) ₃ , ZnSO ₄ , (NH ₄ ) ₂ SO ₄ .

In the above technical solution, the reflux temperature of the SO ₄ ^2- treatment γ-Al ₂ O ₃ described in step ④ is preferably 60-80°C, and the reflux time is preferably 24-72h.

In the above technical solution, the drying temperature described in step ④ is preferably 100-110°C, the drying time is preferably 12-24h, the calcination temperature is preferably 450-550°C, and the calcination time is preferably 4-6h.

In the above technical scheme, the mass ratio of CuO-ZnO-Al ₂ O ₃ and SO ₄ ^2- -γ-Al ₂ O ₃ described in step ⑤ is preferably 2:1-3:1, and the rotational speed of the ball mill is preferably 220- 250r/min, the ball milling time is preferably 3-4h.

In the above technical solution, the flash drying temperature of the monolithic catalyst described in step ⑥ in the muffle furnace is preferably 270-280° C., and the drying time is preferably 5-12 minutes.

In the above technical solution, the reaction conditions of the catalyst described in step (2) are preferably: reaction temperature 230-260°C, reaction pressure 3.0-5.0MPa, reaction space velocity 1000-3000h ^-1 .

The present invention will be further described below in conjunction with embodiment.

Example 1

(1) Cut commercially available honeycomb ceramics with 400 holes/square inch into cube-shaped samples of 12mm×12mm×50mm, soak them in 65wt% HNO ₃ for 2h, wash with deionized water until the filtrate is neutral, and dry at 110°C 12h, 500 ℃ roasting 4h, that is the pretreated honeycomb ceramic matrix.

(2) Immerse the pretreated honeycomb ceramic substrate in 50ml of aluminum sol with a solid content of 10wt%, and put it into a vacuum oven to pump until the glue liquid level rises to close to the mouth of the beaker, stop vacuuming, and take it out after 30s. Rinse the aluminum sol on the surface of the carrier with deionized water, blow out the residual glue in the channels with 0.3MPa compressed air, dry at 110°C for 12h, and bake at 500°C for 4h, that is, the γ-Al ₂ O ₃ coating is loaded Honeycomb ceramic carrier.

(3) Dissolve 48.3g Cu(NO ₃ ) ₂ ·3H ₂ O, 24.3g Zn(NO ₃ ) ₂ ·6H ₂ O and 17.4g Al(NO ₃ ) ₃ ·9H ₂ O in 600ml of distilled water to make a uniform After a stable mixed solution, co-precipitate with Na ₂ CO ₃ solution at 70°C and pH=7.5. After the precipitation is complete, continue to stir and age at 70°C for 1h, filter the precipitate and wash it with deionized water until the filtrate is neutral, dry at 110°C for 16h, and roast at 350°C for 4h to form CuO-ZnO-Al ₂ O ₃ precipitate .

(4) After commercial γ-Al ₂ O ₃ is roasted at 450°C, weigh 16g and 320ml of SO ₄ ^2- (NH ₄ ) ₂ SO ₄ solution with a mass content of 10% and reflux at 75°C for 24h, then A solid sample was obtained by filtration, washed, dried at 110°C for 12 hours, and calcined at 500°C for 4 hours to obtain SO ₄ ^2- -γ-Al ₂ O ₃ .

(5) Mechanically mix 16g of CuO-ZnO-Al ₂ O ₃ precipitate obtained in step (3) with 8g of SO ₄ ^2- -γ-Al ₂ O ₃ in step (4) and put it into a 250ml ceramic ball mill jar, add 126g Water was milled in a ball mill at a speed of 230r/min for 4h to obtain a CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ slurry. Immerse the honeycomb ceramic carrier loaded with γ-Al ₂ O ₃ coating obtained in step (1) in the CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ slurry, and put it in a vacuum oven Pump until air bubbles emerge from the honeycomb ceramic channels, stop vacuuming, take it out after 30 seconds, rinse the slurry on the surface of the carrier with water, blow out the residual slurry in the channels with compressed air, and then place it in a muffle furnace for 8 minutes at 280°C for flash drying . Repeat this impregnation and flash drying process 6 times, that is, CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ with a loading of 1.2 g of active components and a loading of γ-Al ₂ O ₃ of 7.8 wt % -Al ₂ O ₃ /honeycomb ceramic monolithic catalyst finished product.

(6) The monolithic catalyst is packed in a stainless steel pressurized fixed-bed reactor with an inner diameter of 10mm by wrapping it with a sealing ring. H ₂ diluted with N ₂ under normal pressure (H ₂ molar content: 5%, space velocity 1500 h ⁻¹ ) was reduced at 270° C. for 6 hours. The temperature is lowered to 100°C, switched to syngas and then pressurized, and the temperature is programmed to carry out the synthesis reaction. H ₂ /CO in the syngas = 1:1. The reaction conditions are as follows: temperature 240°C, pressure 4.0MPa, space velocity 1500h ^-1 . The reaction results are shown in Table 1.

Example 2

The preparation method of the monolithic catalyst is the same as in Example 1, except that the reaction conditions in step (6) are: temperature 250°C, pressure 4.0MPa, space velocity 1500h ^-1 , and the catalyst was subjected to 100h reaction under these reaction conditions Catalytic performance evaluation, the evaluation results are shown in Figure 1.

Example 3

_{The preparation} ^method of _the monolithic catalyst is the same as that in _Example 1, except that the CuO- _ZnO- The mass of Al ₂ O ₃ precipitate is 8g, the mass of SO ₄ ^2- -γ-Al ₂ O ₃ is 8g, and the mass of added water is 88g. The reaction conditions in step (6) are: temperature 250°C, pressure 4.0MPa, space velocity 1500h ^-1 . The reaction results are shown in Table 1.

Example 4

The preparation method of the monolithic catalyst is the same as in Example 1, except that the (NH ₄ ) ₂ SO solution involved in the step (4) has a SO ₄ ^2- mass content of 15%, _and the reaction in the step (6) The conditions are: temperature 240°C, pressure 4.0MPa, space velocity 1500h ^-1 . The reaction results are shown in Table 1.

Example 5

The preparation method of the monolithic catalyst is the same as in Example 4, except that the reaction conditions in step (6) are: temperature 250°C, pressure 4.0MPa, space velocity 1500h ^-1 . The reaction results are shown in Table 1.

Example 6

The preparation method of the monolithic catalyst is the same as in Example 1, except that the impregnation and flash drying process involved in step (5) is repeated 8 times to obtain 1.6 g of the active component loading, γ-Al ₂ O ₃ A CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ /honeycomb ceramic monolithic catalyst with a loading of 7.8wt% is finished. The reaction conditions in step (6) are: temperature 250°C, pressure 4.0MPa, space velocity 1500h ^-1 . The reaction results are shown in Table 1.

Example 7

The preparation method of the monolithic catalyst is the same as in Example 1, except that the impregnation and flash drying process involved in step (5) is repeated four times to obtain a 0.8 g active component loading, γ-Al ₂ O ₃ A CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ /honeycomb ceramic monolithic catalyst with a loading of 7.8wt% is finished. The reaction conditions in step (6) are: temperature 250°C, pressure 4.0MPa, space velocity 1500h ^-1 . The reaction results are shown in Table 1.

Example 8

The preparation method of the monolithic catalyst is the same as that of Example 1, except that the H ₂ /CO in the synthesis gas involved in the step (6) is 2:1. The reaction conditions are as follows: temperature 250°C, pressure 4.0MPa, space velocity 1500h ^-1 . The reaction results are shown in Table 1.

Example 9

The preparation method of the monolithic catalyst is the same as in Example 4, except that the reaction conditions in step (6) are: temperature 250°C, pressure 3.0MPa, space velocity 1500h ^-1 . The reaction results are shown in Table 1.

Example 10

The preparation method of the monolithic catalyst is the same as in Example 4, except that the reaction conditions in step (6) are: temperature 250°C, pressure 4.0MPa, space velocity 3000h ^-1 . The reaction results are shown in Table 1.

Table 1: Example catalyst reaction results

Catalyst CO conversion rate (%) DME selectivity ^* (%) CH ₃ OH selectivity ^* (%) Example 1 63.10 99.1 0.9

Catalyst CO conversion rate (%) DME selectivity ^* (%) CH ₃ OH selectivity ^* (%) Example 3 72.80 99.8 0.17 Example 4 67.57 99.8 0.18 Example 5 82.86 99.7 0.27 Example 6 73.00 99.0 1.0 Example 7 74.70 99.4 0.6 Example 8 80.79 99.3 0.68 Example 9 70.28 99.5 0.47 Example 10 66.48 99.4 0.58

^* CO ₂ is not included, other small by-products are C2 and C3 hydrocarbons

Claims (10)

1. A monolithic catalyst for producing dimethyl ether from syngas, expressed as CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ /honeycomb ceramics; The honeycomb ceramic is used as the carrier, γ-Al ₂ O ₃ is the inert component coating, and the loading amount of the inert component in each gram of monolithic catalyst is 0.2-0.5g; CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ is the active component, which is loaded on the inert component coating, and the active component loading per gram of monolithic catalyst is 0.6-2.0g . 2. The monolithic catalyst for producing dimethyl ether from syngas as claimed in claim 1, wherein the pore density of the honeycomb ceramic carrier is 200-400 pore/square inch. 3. prepare the method for monolithic catalyst as claimed in claim 1, main steps are: 1) Preparation of honeycomb ceramic carrier loaded with γ-Al ₂ O ₃ coating: immerse the honeycomb ceramic carrier in the aluminum sol, rinse the aluminum sol on the surface after taking it out, blow out the residual aluminum sol in the channels of the honeycomb ceramic carrier, dry and roast The honeycomb ceramic carrier loaded with γ-Al ₂ O ₃ coating is obtained; 2) Preparation of CuO-ZnO-Al ₂ O ₃ methanol synthesis catalyst by co-precipitation method: the nitrate mixed solution of copper, zinc and aluminum and sodium carbonate solution are mixed under the conditions of temperature 50-80°C and pH=6.0-10.0 flow co-precipitation, the resulting precipitation solution is aged at 60-90 ° C, dried and roasted to obtain CuO-ZnO-Al ₂ O ₃ powder, wherein the mass ratio of copper, zinc and aluminum in the nitrate mixed solution is 15-65:10 -40: 2-20; 3) Preparation of SO ₄ ^2- -γ-Al ₂ O ₃ : γ-Al ₂ O ₃ is calcined at 400°C-500°C and then refluxed with acid or salt solution containing SO ₄ ^2- at 50-90°C , to obtain a solid sample by filtering, drying and roasting the obtained solid sample to obtain SO ₄ ^2- -γ-Al ₂ O ₃ , wherein the mass content of SO ₄ ^2- is 1-20%; 4) Preparation of CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ slurry: mix CuO-ZnO-Al ₂ O ₃ in step 2 with SO ₄ ^2- -γ- in step 3 Al ₂ O ₃ is mechanically mixed according to the mass ratio of 1:1-4:1 and then added with water or ethanol for ball milling, wherein the mass ratio of water or ethanol to SO ₄ ^2- -γ-Al ₂ O ₃ is 12-20 : 1, to obtain CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ slurry; 5) Monolith catalyst preparation: impregnate the honeycomb ceramic carrier loaded with γ-Al ₂ O ₃ coating in step 1 into the CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O in step 4 ₃ In the slurry, after taking it out, rinse the slurry on the surface of the carrier, blow out the residual slurry in the carrier channel, and then flash dry at 250-300°C to obtain CuO-ZnO-Al ₂ O ₃ /SO ₄ ^2- -γ-Al ₂ O ₃ /honeycomb ceramic monolithic catalyst. 4. The preparation method according to claim 3, wherein, before step 1, soak the honeycomb ceramic carrier with HNO ₃ with a mass concentration of 30-65%, wash it with water to pH=7.0 after taking it out, and dry it at 100-120°C at 450-550 ℃ roasting and then used in the process of step 1. 5. The preparation method according to claim 3, wherein the acid or salt containing SO ₄ ^2- in step 3 is H ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ , ZnSO ₄ , FeSO ₄ , (NH ₄ ) ₂ SO ₄ , Ti(SO ₄ ) ₂ or mixtures thereof. 6. The preparation method according to claim 3, wherein the drying temperature in step 3 is 90-120° C. for 12-48 hours; the calcination temperature is 400-700° C. for 3-8 hours. 7. The preparation method according to claim 3, wherein the monolithic catalyst in step 5 is flash-dried in a muffle furnace at a drying temperature of 270-280° C. and a drying time of 5-12 minutes. 8. The preparation method as claimed in claim 3, wherein the dipping and flash drying process in step 5 is repeated. 9. The application of the CuO-ZnO-Al ₂ O ₃ /SO ₄ ² --γ-Al ₂ O ₃ /honeycomb ceramic monolithic catalyst according to claim 1 in the synthesis gas DME reaction, the catalyst is packed in In the fixed bed reactor, the H ₂ diluted with N ₂ is reduced under normal pressure at 250-280°C and the space velocity is 1000-3000h ^-1 , and the H ₂ diluted with N ₂ is switched to The synthesis gas is heated up to carry out the synthesis reaction. The synthesis reaction conditions are: temperature 200-280°C, pressure 1-10MPa, space velocity 500-10000h ^-1 . 10. The application as claimed in claim 9, wherein the composition of _H2 diluted with _N2 is N2: _H2 =10-20:1 by volume _ratio ; the volume composition of synthesis gas is: _H2: CO: _CO2 =2:1-2:0.1-2.