CN1153080A - Catalyst for direct preparation of dimethyl ether with synthetic gas - Google Patents

Abstract

Dimethyl ether is produced from synthesis gas in one step on a catalyst that has both methanol synthesis active centers and methanol dehydration active centers. The catalyst of the present invention uses copper, zinc oxide and zirconium oxide as methanol synthesis components, and may also contain an auxiliary element. Using H-type Y or SY or ZSM-5 molecular sieve or mordenite or H-type Y or SY or ZSM-5 molecular sieve containing an auxiliary element as methanol dehydration component, it is prepared by co-precipitation deposition method. The catalyst has the advantages of less generation of _CO2 by-products, good selectivity to dimethyl ether, high catalytic activity, good stability, and simple preparation process. The result of the reaction is that the conversion rate of CO can reach more than 90%, and the selectivity of dimethyl ether is respectively: >95% (to organic products), >80% (to all products including carbon dioxide), good stability, and the reaction can be performed at a relatively low temperature. It is carried out under low pressure, temperature and large space velocity.

Description

Catalyst for direct production of dimethyl ether from synthesis gas

The invention belongs to a method for preparing dimethyl ether from synthesis gas in one step, in particular to a catalyst used and a preparation process thereof.

Dimethyl ether is not only the main intermediate in the improved method of producing gasoline from syngas through methanol conversion, but also an important raw material for the production of various chemical products, and has many unique uses in pharmaceutical, dyestuff, pesticide and other industries. DME may also attract increasing attention as a substitute for city gas or liquefied petroleum gas or even diesel.

The process of producing dimethyl ether from synthesis gas in one step has been patented and reported in literature since the 1970s. Such as US patent, USP4,098,809, USP4,177,167, USP4,375,424, USP4,417,000 Japanese patent JP155496, the People's Republic of China invention patent application publication number CN1087033A and literature Ind.Eng.Chem.Res., Vol.30, No.11 , 1991 P2372-2378. Frankly speaking, the common disadvantage of the various catalysts described in the patent literature is that under the condition of industrial synthesis gas H ₂ /CO=2-3 as the raw material gas, the amount of CO ₂ by-products is too high, or this data is lacking According to reports, the catalysts used in these patents and documents are all made of synthetic methanol metal active components and methanol dehydration acidic components. Fine powders of the active components are uniformly mechanically mixed (dry or wet) together, i.e. the mechanical mixing method, or the synthetic methanol metal active component is impregnated on the methanol dehydration acid component (impregnation method), and the synthetic methanol Active metal components are all concentrated on Cu, Zn, Cr, and its auxiliary element is K. The acidic dehydration component adopts r-Al ₂ O ₃ , mordenite, HY, HZSM-5 molecular sieve before or after modification.

The purpose of this invention is to provide a kind of catalyst and preparation method thereof that are used for the one-step system of dimethyl ether by synthesis gas. Using this catalyst to convert synthesis gas into dimethyl ether, the conversion rate of reactant CO is high, the amount of _CO2 by-products is small, the selectivity of dimethyl ether is high, the stability is good, and the reaction is carried out at a relatively low pressure .

The catalyst for the one-step production of dimethyl ether from synthesis gas of the present invention is composed of synthetic methanol active components and methanol dehydration components, and is characterized in that the synthetic methanol active components are Cu, zinc oxide and zirconium oxide, wherein copper, zinc , The atomic ratio of zirconium is: Cu: (Zn+Zr) = 1: 0.5-5.0, Zn: Zr = 1: 0.3-3.0, the methanol dehydration component is H type Y or SY or ZSM-5 molecular sieve or mordenite, The weight ratio of the synthetic methanol component to the methanol dehydration component is 1:0.3-3.0.

In addition to Cu, zinc oxide and zirconium oxide, the active component for synthesizing methanol in the present invention may also contain one of Sr, Mg, Mn and B as auxiliary element, and the atomic ratio of auxiliary element to Cu is 1:10-100.

In addition to H-type Y or SY or ZSM-5 molecular sieve or mordenite, the methanol dehydration component of the present invention can also contain one of V, Ti, W as an auxiliary element, and the weight ratio of the methanol dehydration component is: 1: 50-500, additive elements are oxides.

The preparation method of catalyst of the present invention comprises the steps:

1) Use Cu·(NO ₃ ) ₂ or other Cu salts, Zn(NO ₃ ) ₂ or other zinc salts, ZrOCl ₂ or ZrO(NO ₃ ) ₂ and one of the salts of additive elements such as Mg(NO ₃ ) ₂ or a mixed solution of Sr(NO ₃ ) ₂ or boric acid and Na ₂ CO ₃ or KCO ₃ or NH ₄ CO ₃ solution or ammonia water co-precipitation, stirring, filtering and washing several times;

2) Using commercial Na-type mordenite or Y or SY or ZSM-5 molecular sieve, using ion exchange technology to make H-type zeolite, or directly using commercial H-type mordenite or Y or SY or ZSM-5 molecular sieve;

3) V ₂ O ₅ or WO ₃ or TiO ₂ loaded on the molecular sieve made in the above 2;

4) adding the fine powder of the molecular sieve described in the above 2 or 3 to a certain amount of distilled water to make a suspension;

5) Add the precipitate prepared in the above 1 to the suspension in the above 4, stir, filter, dry, roast, press and form, and reduce. The calcination temperature is 300-450°C, and the reduction temperature is 180°C-350°C.

The catalyst prepared by the method described above is used in the direct synthesis of dimethyl ether from synthesis gas. The reaction conditions are that the raw material _H2 /CO molar ratio (volume) of the synthesis gas is 1-5, and the mixed gas contains a certain amount of CO ₂ , the ratio of CO/CO ₂ is 5-15, the reaction pressure is 2.0-5.0MPa, the reaction temperature is 220-400℃, the space velocity of the synthesis gas in the reaction can be in the range of 500-10000hr ^-1 , and the more suitable space velocity is 1000-3000hr ^-1 .

The outstanding feature of the catalyst of the present invention is the high dispersion of the active components and the synergistic effect between the active components for synthesizing methanol and the methanol dehydration components, so that the catalyst not only has high activity for synthesizing methanol but also has good dehydration performance , and the addition of Zr played a good role in stabilizing the active center.

Due to this feature of the catalyst, the present invention has the following advantages,

First, the CO conversion rate is high

Second, the generation of _CO2 by-products is small, and the number of moles of _dimethyl ether generated is 2.3-3.5 times that of CO2. moles of _CO2

Third, the selectivity of dimethyl ether is high

Fourth, compared with the C301 catalyst for industrial methanol synthesis, the stability of the catalyst of the present invention is greatly improved, making it applicable in industry.

Realization mode and best embodiment of the present invention

example 1

Bake the commercial H-type ZSM-5 (Si/Al=50) molecular sieve at 120°C for 12 hours, and then roast it in 540°C _N2 gas for 4 hours. After grinding, add a certain amount of distilled water to make H-type ZSM-5 (Si/Al=50) molecular sieve suspension. Weigh quantitative Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , ZrOCl ₂ and dissolve in a certain amount of distilled water, co-precipitate this mixed solution with Na ₂ CO ₃ solution, stir, filter, and wash the precipitate 4-6 times. Add this precipitate to the above-mentioned H-type ZSM-5 molecular sieve suspension, stir, filter, dry at 120°C, roast at 350°C, press into tablets at 16MPa, and then crush it into particles with a sieve size of 20-40 mesh to obtain catalyst A . Its activity and selectivity are shown in the following table.

Example 2

Weigh quantitative Mg(NO ₃ ) ₂ , Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , ZrOCl ₂ and dissolve them in a certain amount of distilled water, and co-precipitate this mixed solution with Na ₂ CO ₃ solution, Stir, filter, and wash the precipitate 4-6 times. Add this precipitate to the same H-type ZSM-5 (Si/Al=50) molecular sieve suspension as in Example 1, stir, filter, dry, roast, and compress into tablets under 16MPa, and then crush it into a 20-40 mesh sieve particles to obtain catalyst B. Its activity and selectivity are shown in the following table.

Example 3

Weigh quantitative Mn(NO ₃ ) ₂ , Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , ZrOCl ₂ and dissolve in a certain amount of distilled water, and co-precipitate this mixed solution with Na ₂ CO ₃ solution, Stir, filter, and wash the precipitate 4-6 times. Add this precipitate to the same H-type ZSM-5 (Si/Al=50) molecular sieve suspension as in Example 1, stir, filter, dry, roast, and compress under 16MPa, and then crush it into 20-40 mesh sieves particles to obtain catalyst C. Its catalytic performance is shown in the following table.

Example 4

Weigh quantitative H ₃ BO ₃ , Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , ZrOCl ₂ and dissolve them in a certain amount of distilled water, co-precipitate this mixed solution with Na ₂ CO ₃ solution, stir, Filter and wash the precipitate 4-6 times. Add this precipitate to the same H-type ZSM-5 (Si/Al=50) molecular sieve suspension as in Example 1, stir, filter, dry, calcinate and compress under 16MPa, and then break into 20-40 mesh sieves. The particles yielded Catalyst D. Its catalytic performance is shown in the following table.

Example 5

Commercial Na-type ZSM-5 (Si/Al=84) molecular sieves were exchanged into HZSM-5 (Si/Al=84) through 0.15N HCl solution four times. Then calcined for 4 hours (550°C) to obtain H-type ZSM-5 (Si/Al=84). Add a certain amount of distilled water to this molecular sieve to make a suspension. Weigh Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , ZrOCl ₂ and dissolve them in a certain amount of distilled water, co-precipitate the mixed solution and Na ₂ CO ₃ solution in parallel, stir, filter, and wash the precipitate 4-6 times. The precipitate was added to the H-type ZSM-5 (Si/Al=84) molecular sieve suspension, dried, roasted, pressed into tablets, and crushed into 20-40 mesh particles according to the conditions described in Example 1 to obtain catalyst E. Its activity and selectivity are shown in the following table.

Example 6

The commercial Na-type Y molecular sieve was exchanged into NH ₄ Y by 1NNH ₄ Cl solution six times. Roast under the same conditions as Example 5 to obtain HY molecular sieve, add a certain amount of distilled water after grinding, and prepare HY molecular sieve suspension. According to the predetermined amount, weigh Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , ZrOCl ₂ and dissolve them in a certain amount of distilled water. The same procedure and conditions as in Example 1 were used to obtain a precipitate, which was added to the above HY Suspension, the procedure and condition identical with example 1 are made the particle of 20-40 mesh size, obtains catalyst F. Its activity and selectivity are shown in the following table.

Example 7

The commercial Na-type SY (ultrastable Y) molecular sieve was exchanged into NH ₄ SY by 2N NH4NO ₃ solution six times. Roast under the same conditions as Example 5 to obtain HSY molecular sieve, after grinding, add a certain amount of distilled water to prepare HSY molecular sieve suspension. Weigh Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , ZrOCl ₂ and dissolve them in a certain amount of distilled water respectively according to the predetermined amount. The same procedure and conditions as in Example 1 are used to obtain a precipitate, and the precipitate is added to the above-mentioned HSY for suspension. liquid, the same procedures and conditions as in Example 1 were used to make particles with a sieve size of 20-40 to obtain catalyst G. Its activity and selectivity are shown in the following table.

Example 8

Weigh quantitatively pure ammonium tungstate (NH ₄ ) ₆ H ₅ [H ₂ (WO ₄ ) ₆ ]·H ₂ O and add quantitative distilled water to prepare a solution. Immerse commercial H-type ZSM-5 (Si/Al=50) molecular sieve fine powder in ammonium tungstate solution, stir for 24 hours, dry at 120°C, and bake at 540°C to obtain WO ₃ /HZSM-5 (Si/Al=50 ). After grinding, add a certain amount of distilled water to make a suspension. Weigh Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , ZrOCl ₂ and dissolve them in a certain amount of distilled water respectively according to the predetermined amount. The same procedure and conditions as Example 1 are used to obtain a precipitate, which is added to the above WO ₃ /HZSM-5 (Si/Al=50) suspension, the same procedures and conditions as in Example 1 were used to make particles with a sieve size of 20-40 mesh to obtain catalyst H. Its activity and selectivity are shown in the following table.

Example 9

Weigh quantitative analytical pure TiCl ₄ , add quantitative distilled water, then add commercial H-type ZSM-5 (Si/Al=50) molecular sieve fine powder, stir for 24 hours, wash until the filtrate has no Cl ^- ions, and then do the same as in Example 8 The procedures and conditions of TiO ₂ /HZSM-5 (Si/Al=50) were prepared, and a certain amount of distilled water was added after grinding to prepare TiO ₂ /HZSM-5 (Si/Al=50) suspension. Weigh Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , ZrOCl ₂ and dissolve them in a certain amount of distilled water respectively according to the predetermined amount. The same procedure and conditions as Example 1 are used to obtain a precipitate, and this precipitate is added to the above procedure and The conditions are to make particles with a sieve size of 20-40 meshes to obtain the catalyst I. Its catalytic performance is shown in the following table.

Example 10

Weigh quantitative analytically pure ammonium metavanadate NH ₄ VO ₃ and add quantitative distilled water to prepare a solution. Immerse commercial H-type ZSM-5 (Si/Al=50) molecular sieve fine powder in this solution, stir for 24 hours, and prepare V ₂ O ₅ /HZSM-5 (Si/al= 50), adding a certain amount of distilled water after grinding to make V ₂ O ₅ /HZSM-5 (Si/Al=50) suspension. Weigh Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , ZrOCl ₂ and dissolve them in a certain amount of distilled water respectively according to the predetermined amount. The same procedures and conditions as Example 1 are used to obtain a precipitate, which is added to the above V ₂ O ₅ /HZSM-5 (Si/Al=50) suspension was prepared into particles with a mesh size of 20-40 by the same procedures and conditions as in Example 1 to obtain Catalyst J. Its activity and selectivity are shown in the following table.

Example 11

Dissolve Mg(NO ₃ ) ₂ , Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , and ZrOCl ₂ in a certain amount of distilled water according to the predetermined amount, and prepare a precipitate with the same procedure and conditions as in Example 1. The mixture was added to the same V ₂ O ₅ /HZSM-5 (Si/Al=50) suspension as in Example 10, and the same procedures and conditions as in Example 1 were used to prepare particles with a mesh size of 20-40 to obtain Catalyst K. Its catalytic performance is shown in the following table.

Example 12

Sr(NO ₃ ) ₂ , Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , and ZrOCl ₂ were weighed and dissolved in a certain amount of distilled water according to the predetermined amount, and the precipitate was prepared by the same procedure and conditions as in Example 1. The precipitate was added to the V ₂ O ₅ /HZSM-5 (Si/Al=50) suspension phase of Example 10, and the same procedures and conditions as Example 1 were used to prepare particles with a mesh size of 20-40 to obtain catalyst L. Its catalytic performance is shown in the following table.

Example 13

Load 1.5ml of the catalyst L1.5ml prepared in the above example 12 on the continuous flow fixed bed micro-reactor, first use Ar gas to purge at 140°C for 0.5 hours, the flow rate of Ar gas is controlled at about GHSV to be 1200hr ^- 1, and then use the temperature program The instrument carries out the range-rising reduction, the space velocity of hydrogen is 1500hr ^- 1, the heating rate is controlled at about 1°C/min, the total reduction time is 6 hours, and the maximum reduction temperature does not exceed 250°C. Lower the temperature to 200°C to improve the synthesis gas and then slowly raise the temperature. The reaction conditions adopted are reaction pressure 4.0MPa, reaction temperature 285°C, the gas used for the reaction is synthesis gas (H ₂ CO = 2), and GHSV is 1500hr ^-1 under the reaction conditions, The results of the 100-hour life test on Catalyst L are listed in Table 2.

Table 1 Reaction results on AL catalyst Catalyst temperature °C selectivity (%) CO conversion rate (%) CH ₄ CH ₃ OH C ₂ +C ^- ₂ CO ₂ DME DME (for all (for organic) products) A 280B 280C 280D 290E 280F 280G 290H 280I 280J 280K 280L 285 0.4 0.5 0.5 14.8 83.8 98.80.3 0.7 0.6 13.7 84.7 98.20.3-0.6 12.4 86.7 98.60.3 0.2 17.5 80.2 97.80.2 0.7 1.8 81.9 99.00.3 0.1 83.3 97.8.3 2.5.5.5.5.5.5.5.5 0.6 0.9 17.4 80.6 98.20.5 1.0 0.9 13.7 83.9 98.10.3 0.5 0.4 14.0 84.8 99.10.4 0.5 0.6 13.9 84.6 97.80.4 0.4 0.7 15.3 83.3 98. 89.990.785.686.789.387.090.687.987.890.691.492.0

Table 2 Life Test Results Cumulative Reaction Time of Catalyst L (h) (15min) 1 15 27 65 75 100 CO Conversion (%) 88.5 88.0 88.4 86.8 81.7 79.3 74.1 DME Selectivity (%) 98.1 98.2 97.5 98.3 97.5 98.8 98.4( For organic product) and initial conversion 100 99.4 99.9 98.1 92.3 89.6 83.7 rate ratio (%) industrial synthetic methanol catalyst C301 cumulative reaction time (h) (15min) 1 17 40 65 89 100CO conversion rate (%) 39.8 37.8 33.2 30.7 28.0 25.6 22.5 CH ₃ OH selectivity (%) 89.7 85.5 86.4 86.9 86.5 86.6 85.4 (for organic products) and the initial conversion 100 95.0 83.4 77.1 70.4 64.3 56.5 rate ratio (%) Note: the reaction temperature is 260 ° C and other reaction conditions are the same as catalyst L

Claims (6)

1. a catalyst of producing dimethyl ether by synthesis gas one step is to form with synthesizing methanol active constituent and methanol dehydration component, it is characterized in that the synthesizing methanol active constituent is Cu, zinc oxide and zirconia, wherein the atomic ratio of copper, zinc, zirconium is: Cu: (Zn+Zr)=1: 0.5-5.0, Zn: Zr=1: 0.3-3.0, the methanol dehydration component is H type Y or SY or ZSM-5 molecular sieve or modenite, and the weight ratio of synthesizing methanol component and methanol dehydration component is 1: 0.3-3.0.

2. catalyst as claimed in claim 1, it is characterized in that the synthesizing methanol active constituent except that Cu, zinc oxide, zirconia, also can contain Sr, Mg, Mn, B one of them as auxiliary element, the atomic ratio of auxiliary element and Cu is: 1: 10-100.

3. catalyst as claimed in claim 1, it is characterized in that the methanol dehydration component is except that H type Y or SY or ZSM-5 molecular sieve or modenite, can also contain V, Ti, W one of them as auxiliary element, with the weight ratio of methanol dehydration component be: 1: 50-500, auxiliary element is oxide.

4. comprise the steps: as Preparation of catalysts method as described in claim 1 or 2 or 3

1) adopts Cu (NO ₃) ₂Or other Cu salt, Zn (NO ₃) ₂Or other zinc salt, ZrOCl ₂Or ZrO (NO ₃) ₂And one of the salt of auxiliary element is as Mg (NO ₃) ₂Or Sr (NO ₃) ₂Or the mixed solution of boric acid and Na ₂CO ₃Or KCO ₃Or NH ₄CO ₃Solution or ammoniacal liquor also flow co-precipitation, stirring, filtration, washing for several times;

2) adopt commodity Na type modenite or Y or SY or ZSM-5 molecular sieve, utilize ion exchange technique to make H type zeolite, or directly adopt commodity H type modenite or Y or SY or ZSM-5 molecular sieve;

3) V ₂O ₅Or WO ₃Or TiO ₂Be supported on the above-mentioned 2 made molecular sieves;

4) with above-mentioned 2 or the fine powder of 3 described molecular sieves, add a certain amount of distilled water and make suspension;

5) above-mentioned 1 made sediment is added in above-mentioned 4 the suspension, stirring, filtration, drying, roasting, compression moulding, reduction, sintering temperature is 300-450 ℃, reduction temperature is 180 ℃-350 ℃.

5. a utilization goes on foot the course of reaction of producing dimethyl ether according to claim 1 or 2 or 3 described catalyst by synthesis gas one, it is characterized in that reaction condition is: reaction temperature: 220-400 ℃; Reaction pressure: 2.0-5.0MPa; Reaction gas H ₂/ CO mol ratio (volume): 1: 0.2-1.

6. according to the described course of reaction of claim 5, it is characterized in that containing in the reactant synthesis gas a certain amount of CO ₂, CO/CO ₂Than being 5-15%.