CN101020139A - Catalyst for preparing methanol with synthetic gas and its prepn process - Google Patents

Abstract

The invention discloses a catalyst for producing methanol from synthesis gas and a preparation method thereof, relating to a catalyst for producing methanol, in particular to a catalyst for synthesizing methanol by reacting CO and _H2 and a preparation method thereof. Provided is a low-temperature, high-activity, good thermal stability heat-resistant copper-based catalyst for synthesizing methanol by reacting CO and H ₂ and a preparation method thereof. The catalyst is composed of heat insulating agent M and Cu-Zn-Al mixed oxide. The heat insulating agent M is selected from γ-Al ₂ O ₃ , white carbon black, silicon aluminum molecular sieve, hydrotalcite, magnesium aluminum spinel, titanium dioxide, At least one of 5A molecular sieves, ZSM-5, and 3A molecular sieves, Cu, Zn, and Al oxides are oxides obtained by calcination of soluble salts without Cl- ^and SO ₄ ^2- , and the proportion of each component of the catalyst is measured by atomic ratio. 30-70, Zn 20-60, Al 7-15; the addition amount of heat insulating agent M is 1%-20% of the mass of the catalyst in terms of mass ratio.

Description

Catalyst for methanol production from synthesis gas and preparation method thereof

technical field

The invention relates to a catalyst for producing methanol, in particular to a catalyst for synthesizing methanol by reacting CO and _H2 and a preparation method thereof.

Background technique

Methanol is an important basic organic chemical raw material. In recent years, with the rapid development of science and technology and the change of energy structure, methanol has opened up more new uses. The zinc-chromium catalyst successfully developed by the German BASF company, due to its low activity, needs to be operated under high temperature (317-319°C) and high pressure (25-35MPa) conditions in order to obtain higher catalytic activity and higher conversion rate , is gradually being phased out. The copper-based catalyst successfully developed by ICI Company of the United Kingdom and Lurgi Company of Germany is widely used because of its good activity, high selectivity, and a low-pressure (5-10MPa) catalyst. At present, industrial methanol synthesis catalysts are mainly Cu-Zn-Al catalytic systems. Due to the large thermal effect (greater than 94Kcal) of syngas to methanol, the pure ternary copper-based catalysts have poor thermal stability and short service life.

In order to overcome the Achilles heel of industrial methanol synthesis catalysts, in recent years, some patents at home and abroad have reported a series of heat-resistant copper-based catalysts for methanol synthesis. European patent EP0864360 discloses a highly active heat-resistant copper-based catalyst, which is a metal oxide of Cu/Zn/Al/SiO ₂ /N coexistence, and N is one or more oxides of zirconium, gallium, and palladium. The mass fractions are: 20%-60%, 10%-50%, 2%-10%, 0.3%-0.9%, 0%-10%, 0%-10%, and the calcination temperature is 480-690°C.

Chinese patent CN1173393 introduces the catalyst of Cu/Zn/Al/M'/M" five-component coexistence metal oxide prepared by mixed co-precipitation method. M' is selected from metal scandium (Se) and yttrium (Y) of IIIB group Or lanthanide rare earth, M" is selected from titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), molybdenum ( Mo), tungsten (W), its composition (atomic ratio) Cu is 20-60, Zn is 25-45, Al is 8-10, M' is 0.1-5, and M" is 0.1-6.

Chinese patent CN1660493 introduces a new copper-based methanol synthesis catalyst, the main component of which is a copper-zinc active matrix and a secondary component of a thermally stable large-surface active carrier.

Contents of the invention

The object of the present invention is to provide a low temperature, high activity, good thermal stability, heat-resistant copper-based catalyst for synthesizing methanol by CO and _H2 reaction and its preparation method.

The catalyst for producing methanol from synthesis gas according to the present invention consists of heat insulating agent M and Cu-Zn-Al mixed oxide, and the heat insulating agent M is selected from γ-Al ₂ O ₃ , white carbon black, silicon At least one of aluminum molecular sieve, hydrotalcite, magnesium aluminum spinel, titanium dioxide, 5A molecular sieve, ZSM-5, and 3A molecular sieve, and the Cu, Zn, and Al oxides are free of Cl ^- and SO ₄ ^2- The oxide obtained by calcining the soluble salt, the soluble salt is preferably nitrate or acetate. The distribution ratio of each component of the catalyst is measured by atomic ratio as Cu is 30-70, preferably 35-65; Zn is 20-60, preferably 30-50; Al is 7-15, preferably 8-12; The thermal agent M is added in a mass ratio, and the added amount is 1% to 20% of the mass of the catalyst, preferably 8% to 12%.

The preparation method of the catalyst of methanol by syngas of the present invention, its steps are as follows:

1) According to the distribution ratio of the catalyst group, the measured soluble salts of Cu, Zn and Al are made into a mixed aqueous solution;

2) Add it to the precipitant solution at 65-70°C under stirring, and control the pH=7.0-8.5 as the end point; the precipitant is

Na ₂ CO ₃ with content ≥98.5%, Cl ^- ≤0.1%;

3) washing the precipitate with deionized water until there is no Cl ⁻ ;

4) Add the measured heat insulating agent M to the sediment according to the proportion, stir for 15-25 minutes, filter and drain;

5) Dried at 110-120°C, calcined at 450-500°C for 2-3 hours, ground, pressed into tablets, and then crushed to 16-40 mesh.

The catalyst needs to be activated before use, and it can be activated (reduced) in a fixed-bed reactor, using low H ₂ (H ₂ /N ₂ =3/97) for 16-20 hours, and the maximum reduction temperature is 245°C.

The activity evaluation of the catalyst adopts one way of gas splitting into two fixed-bed reactors, and the temperature-raising reduction and activity evaluation are carried out in parallel. The catalyst loading amount is 0.5ml, the feed gas composition is CO: _{H 2} :CO ₂ :N ₂ =14:76:5:5, the reaction pressure is 2.0MPa, the space velocity is 3000h ^-1 , the evaluation temperature is 245°C, and the measurement results become the initial activity. Then the catalyst was heat-treated at 450°C for 5 hours in a syngas atmosphere, and then lowered to 245°C. The measured result was called activity after heat treatment. The product was analyzed by gas chromatography, and the activity of the catalyst was represented by the space-time yield (g.ml ^-1 _cat .h ^-1 ). The catalyst of the invention has the characteristics of good thermal stability and high methanol selectivity, and after heat treatment at 450 DEG C, there are few by-products and the methanol selectivity is stable.

Detailed ways

Below by embodiment the present invention will be further described.

Example 1

1) Take 90ml of 1M Cu(NO ₃ ) ₂ solution, 45ml of 1M Zn(NO ₃ ) ₂ solution and 16.5ml of 1M Al(NO ₃ ) ₃ solution in a 400ml beaker and stir to mix.

2) Take 150ml of 1M Na ₂ CO ₃ solution and place it in a 1000ml beaker, heat it to 70°C, add the mixture obtained in step 1 to the Na ₂ CO ₃ solution at a rate of 20ml/min under stirring, stop heating and stirring after aging for 2 hours , at this time the pH of the mixed solution=7.5.

3) The precipitate prepared in step 2 was washed with deionized water at 60° C. to be free of Cl ⁻ , and 1.0 g of hydrotalcite was added to the precipitate and stirred for 20 min.

4) Filtration, drying the filter cake at 110°C for 4h, crushing, and calcining at 450°C for 3h.

5) Finally, the mixed oxide obtained in step 4 is pressed into tablets, crushed and sieved into 16-40 mesh for later use. The ratio of the obtained catalyst is Cu:Zn:Al=60:30:11 (atomic ratio).

The catalyst is activated (reduced) in a fixed-bed reactor before use, and is reduced with low H ₂ (H ₂ /N ₂ =3/97) for 16-20 hours, and the maximum reduction temperature is 245°C.

The activity evaluation of the catalyst adopts one way of gas splitting into two fixed-bed reactors, and the temperature-raising reduction and activity evaluation are carried out in parallel. The product was analyzed by gas chromatography, and the activity of the catalyst was represented by the space-time yield (g.ml ^-1 _cat .h ^-1 ). The catalyst loading amount is 0.5ml, the feed gas composition is CO: _{H 2} :CO ₂ :N ₂ =14:76:5:5, the reaction pressure is 2.0MPa, the space velocity is 3000h ^-1 , the evaluation temperature is 245°C, and the measurement results The initial activity was 0.15g.ml ^- _cat .h ^- , and then the catalyst was heat-treated at 450°C for 5h in a syngas atmosphere, and then lowered to 245°C. The measured activity after heat treatment was 0.12g.ml ^-1 _cat .h ^-1 .

Comparative example 1

The steps and conditions are as in Example 1, step 3) without adding heat insulating agent M, then the initial activity of the catalyst is 0.13g.ml ^-1 _cat .h ^-1 , and the activity after heat treatment is 0.08g.ml ^-1 _cat .h ^-1 .

Embodiment 2～3

The type of heat insulating agent and the added quality were changed, and other conditions and preparation methods were the same as those in Example 1. The results of activity measurement are shown in Table 1.

Example 4

1) Take 90ml of 1M Cu(NO ₃ ) ₂ solution, 45ml of 1M Zn(NO ₃ ) ₂ solution and 12ml of 1M Al(NO ₃ ) ₃ solution in a 400ml beaker and stir to mix.

2) Take 150ml of 1M Na ₂ CO ₃ solution and place it in a 1000ml beaker, heat it to 70°C, add the mixture obtained in step 1 to the Na ₂ CO ₃ solution at a rate of 20ml/min under stirring, stop heating and stirring after aging for 2 hours , at this time the pH of the mixed solution=7.5.

3) The precipitate prepared in step 2 was washed with deionized water at 60°C until Cl ⁻ was free, and 1.1 g of 3A molecular sieve was added to the precipitate and stirred for 20 min.

Steps 4 to 5 are the same as steps 4 to 5 in Example 1, and the activity evaluation of the catalyst is the same as in Example 1. The results are shown in Table 1.

Example 5

1) Take 90ml of 1M Cu(NO ₃ ) ₂ solution, 90ml of 1M Zn(NO ₃ ) ₂ solution and 24ml of 1M Al(NO ₃ ) ₃ solution in a 400ml beaker and stir to mix.

2) Take 200ml of 1M Na ₂ CO ₃ solution and place it in a 1000ml beaker, heat it to 70°C, add the mixture obtained in step 1 to the Na ₂ CO ₃ solution at a rate of 20ml/min under stirring, and stop heating after aging for 2 hours Stir, and the pH of the mixture is 7.5.

3) The precipitate prepared in step 2 was washed with deionized water at 60° C. to be free of Cl ⁻ , and 1.0 g of titanium dioxide was added to the precipitate and stirred for 15 min.

The rest of the steps are the same as in Example 1, and the activity measurement results of the catalyst are shown in Table 1.

Example 6

1) Take 110ml of 1M Cu(NO ₃ ) ₂ solution, 60ml of 1M Zn(NO ₃ ) ₂ solution and 20ml of 1M Al(NO ₃ ) ₃ solution in a 400ml beaker and stir to mix.

2) Take 190ml of 1M Na ₂ CO ₃ solution and place it in a 1000ml beaker, heat it to 70°C, add the mixture obtained in step 1 to the Na ₂ CO ₃ solution at a rate of 20ml/min under stirring, stop heating and stirring after aging for 2 hours , pH of the mixed solution=7.5.

3) Wash the precipitate with deionized water at 60°C until there is no Cl ⁻ , add 1.2 g of MgAl ₂ O ₄ to the precipitate and stir for 25 min. The rest of the steps are the same as in Example 1, and the activity measurement results of the catalyst are shown in Table 1.

Example 7

1) Take 80ml of 1M Cu(NO ₃ ) ₂ solution, 70ml of 1M Zn(NO ₃ ) ₂ solution and 20ml of 1M Al(NO ₃ ) ₃ solution in a 400ml beaker and stir to mix.

2) Take 170ml1M Na ₂ CO ₃ solution and place it in a 1000ml beaker, heat it to 70°C, add the mixed solution obtained in step 1 to the Na ₂ CO ₃ solution at a rate of 20ml/min under stirring, stop heating and stirring after aging for 2 hours , pH of the mixed solution=7.5.

3) Wash the precipitate with deionized water at 60°C until there is no Cl ⁻ , add 1.0 g of white carbon black to the precipitate and stir for 20 min. The rest of the steps are the same as in Example 1, and the activity measurement results of the catalyst are shown in Table 1.

Table 1 Evaluation results of adding different heat insulating agents

Example   Methanol yield (g.ml ^-1 _cat .h ^-1 ) Cu:Zn:Al The amount of M added Initial activity   Activity after heat treatment 2 60:30:11 1.0g ZSM-5 0.13 0.10 3 60:30:11 0.8g 5A molecular sieve 0.12 0.09 4 60:45:8   1.1g 3A molecular sieve 0.13 0.11 5 45:45:12   1.0g titanium dioxide 0.14 0.11 6 55:30:10 1.2g MgAl ₂ O ₄ 0.13 0.09 7 40:35:10   1.0g white carbon black 0.13 0.12

Example 8

1) Take 72ml of 1M Cu(C ₂ H ₄ O ₂ ) ₂ solution, 100ml of 1M Zn(C ₂ H ₄ O ₂ ) ₂ solution and 18ml of 1MAl(NO ₃ ) ₃ solution in a 400ml beaker, stir and mix.

2) Take 180ml of 1M Na ₂ CO ₃ solution and place it in a 1000ml beaker, heat it to 70°C, add the mixture obtained in step 1 to the Na ₂ CO ₃ solution at a rate of 20ml/min under stirring, stop heating and stirring after aging for 2 hours , at this time the pH of the mixed solution=7.8.

3) The precipitate was washed with deionized water at 70°C until there was no Cl ⁻ , and 1.0 g of white carbon black was added to the precipitate and stirred for 20 min.

4) Filtration, drying the filter cake at 110°C for 4h, crushing, and calcining at 500°C for 3h.

5) Finally, crush and sieve the obtained mixed oxide into 16-40 mesh for later use.

The obtained catalyst formula is Cu:Zn:Al=36:50:9 (atomic ratio), and the activity measurement of the catalyst is the same as in Example 1. The result was that the initial activity was 0.13g.ml ^-1 _cat .h ^-1 , and the activity after heat treatment was 0.11g.ml ^-1 _cat .h ^-1 .

Embodiment 9～10

Change the heat insulating agent kind and add quality, other conditions and preparation method are the same as embodiment 8. The results of the activity assay are shown in Table 2.

Example 11

1) Take 90ml of 1M Cu(C ₂ H ₁ O ₂ ) ₂ solution, 45ml of 1M Zn(C ₂ H ₄ O ₂ ) ₂ solution and 16.5ml of 1M Al(NO ₃ ) ₃ solution in a 400ml beaker, stir and mix.

2) Take 142ml of 1M Na ₂ CO ₃ solution and place it in a 1000ml beaker, heat it to 70°C, add the mixture obtained in step 1 to the Na ₂ CO ₃ solution at a rate of 20ml/min under stirring, stop heating and stirring after aging for 2 hours , at this time the pH of the mixed solution=7.8.

3) The precipitate was washed with 70°C deionized water until there was no Cl ⁻ , and 0.9 g of γ-Al ₂ O ₃ was added to the precipitate and stirred for 20 min.

Remaining steps are the same as in Example 8, and the results of the activity measurement of the catalyst are shown in Table 2.

Example 12

1) Take 90ml of 1M Cu(C ₂ H ₄ O ₂ ) ₂ solution, 66ml of 1M Zn(C ₂ H ₄ O ₂ ) ₂ solution and 18ml of 1M Al(NO ₃ ) ₃ solution in a 400ml beaker, stir and mix.

2) Take 165ml of 1M Na ₂ CO ₃ solution and place it in a 1000ml beaker, heat it to 70°C, add the mixture obtained in step 1 to the Na ₂ CO ₃ solution at a rate of 20ml/min under stirring, stop heating and stirring after aging for 2 hours , at this time the pH of the mixed solution=7.8.

3) The precipitate was washed with deionized water at 70°C until there was no Cl ⁻ , and 0.7 g of 3A molecular sieve was added to the precipitate and stirred for 20 min.

Remaining steps are the same as in Example 8, and the results of the activity measurement of the catalyst are shown in Table 2. Activity assay results are shown in Table 2

Example 13

1) Take 90ml of 1M Cu(C ₂ H ₄ O ₂ ) ₂ solution, 45ml of 1M Zn(C ₂ H ₄ O ₂ ) ₂ solution and 18ml of 1M Al(NO ₃ ) ₃ solution in a 400ml beaker, stir and mix.

3) Take 141ml of 1M Na ₂ CO ₃ solution and place it in a 1000ml beaker, heat it to 70°C, add the mixture obtained in step (1) to the Na ₂ CO ₃ solution at a rate of 20ml/min under stirring, and age for 2 hours Stop heating and stirring, and the pH of the mixed solution is now 7.8.

3) The precipitate was washed with deionized water at 70°C until there was no Cl ⁻ , and 1.1 g of 3A molecular sieve was added to the precipitate and stirred for 20 min.

Remaining steps are the same as in Example 8, and the results of the activity measurement of the catalyst are shown in Table 2.

Example 14

1) Take 90ml of 1M Cu(C ₂ H ₄ O ₂ ) ₂ solution, 90ml of 1M Zn(C ₂ H ₄ O ₂ ) ₂ solution and 20ml of 1M Al(NO ₃ ) ₃ solution in a 400ml beaker, stir and mix.

2) Take 190ml of 1M Na ₂ CO ₃ solution and place it in a 1000ml beaker, heat it to 70°C, add the mixture obtained in step 1 to the Na ₂ CO ₃ solution at a rate of 20ml/min under stirring, stop heating and stirring after aging for 2 hours , at this time the pH of the mixed solution=7.8.

3) The precipitate was washed with deionized water at 70°C until there was no Cl ⁻ , and 1.4 g of 3A molecular sieve was added to the precipitate and stirred for 20 min.

Remaining steps are the same as in Example 8, and the results of the activity measurement of the catalyst are shown in Table 2.

Table 2 Evaluation results of adding different heat insulating agents M

Example Raw material formula Methanol yield (g.ml ^- _cat .h ^- ) Cu:Zn:Al The amount of M added Initial activity   Activity after heat treatment 9 36:50:9 0.3g titanium dioxide and 0.7g5A molecular sieve 0.12 0.09 10 36:50:9 1.0g Hydrotalcite 0.12 0.10 11 60:30:11 0.9g γ-Al ₂ O ₃ 0.11 0.10 12 30:22:8 0.7g 3A molecular sieve 0.10 0.08 13 60:30:12 1.1g 3A molecular sieve 0.12 0.10 14 45:45:10 1.4g 3A molecular sieve 0.13 0.11

Claims (7)

1. A catalyst for producing methanol from synthesis gas, characterized in that the catalyst is composed of heat insulating agent M and Cu-Zn-Al mixed oxide, and the heat insulating agent M is selected from γ-Al ₂ O ₃ , white At least one of carbon black, silicon-aluminum molecular sieve, hydrotalcite, magnesium-aluminum spinel, titanium dioxide, 5A molecular sieve, ZSM-5, and 3A molecular sieve, and the Cu, Zn, and Al oxides are free of Cl ^- , SO ₄ The oxide obtained by calcination of the soluble salt of ^2- , the distribution ratio of each component of the catalyst is 30-70 according to the atomic ratio, Cu is 30-70, Zn is 20-60, and Al is 7-15; 1% to 20% of the mass of the catalyst. 2. The catalyst for producing methanol from syngas as claimed in claim 1, characterized in that the distribution ratio of each component of the catalyst is 35-65 in atomic ratio; Cu is 35-65; Zn is 30-50; Al is 8-12. 3. The catalyst for producing methanol from syngas as claimed in claim 1, characterized in that the addition amount of the heat insulating agent M in terms of mass ratio is 8% to 12% of the mass of the catalyst. 4. The catalyst for producing methanol from syngas as claimed in claim 1, characterized in that said soluble salt is selected from nitrate or acetate. 5. as claimed in claim 1, is characterized in that its steps are as follows: 1) According to the distribution ratio of the catalyst group, the measured soluble salts of Cu, Zn and Al are made into a mixed aqueous solution; 2) Add it into the precipitant solution at 65-70°C under stirring, and control the pH=7.0-8.5 as the end point; the precipitant is Na ₂ CO ₃ ; 3) washing the precipitate with deionized water until there is no Cl ⁻ ; 4) Add the measured heat insulating agent M to the sediment according to the proportion, stir for 15-25 minutes, filter and drain; 5) Dried at 110-120°C, calcined at 450-500°C for 2-3 hours, ground, pressed into tablets, and then crushed to 16-40 mesh. 6. The preparation method of catalyst for producing methanol from syngas as claimed in claim 5, characterized in that said precipitant is Na ₂ CO ₃ with content ≥ 98.5%, Cl ⁻ ≤ 0.1%. 7. The preparation method of the catalyst for producing methanol from syngas as claimed in claim 5, characterized in that the drying time is 4 hours.