CN102091628A - Method for preparing low-carbon mixed alcohol catalyst by synthesis gas - Google Patents

Abstract

The invention relates to a method for preparing low-carbon mixed alcohol (with 1 to 5 carbon atoms) catalyst by synthesis gas (CO and H2), which belongs to the technical field of chemical industry. The method is characterized by comprising the following steps of: preparing (CuO-ZnO-Al2O3-ZrO2)-MgO composite oxide by compounding MgO and CuO-ZnO-Al2O3-ZrO2; and with (CuO-ZnO-Al2O3-ZrO2)-MgO as a catalyst and synthesis gas as raw gas, preparing C1-C5 mixed alcohol under the conditions of heating and pressurizing. The (CuO-ZnO-Al2O3-ZrO2)-MgO catalyst prepared by the method of the invention has higher time space yield of C2-C5 mixed alcohol than that of CuO-ZnO-Al2O3-ZrO2 catalyst.

Description

A method for preparing low-carbon mixed alcohol catalyst from synthesis gas

technical field

The invention relates to a catalyst for producing low-carbon mixed alcohols (alcohols with 1 to 5 carbon atoms) from synthesis gas (CO+H ₂ ) and a preparation method thereof, more specifically a preparation (CuO-ZnO- The method of Al ₂ O ₃ -ZrO ₂ )-MgO catalyst belongs to the technical field of chemical industry.

Background technique

Catalytic hydrogenation of carbon monoxide to synthesize low-carbon mixed alcohols (C ₁ ～C ₅ alcohols) is one of the important ways for the clean utilization of coal resources. With the increasing requirements of environmental protection, the research on the production of low-carbon mixed alcohols from syngas has received special attention. Among them, C ₂ ~C ₅ mixed alcohols are environmentally friendly liquid fuel additives (without sulfur, nitrogen, aromatic compounds, etc.), which have high added value and can directly replace the potentially polluting methyl tert-butyl ether (MTBE) Become a high-quality and clean gasoline additive. The production of syngas from coal and the production of low-carbon mixed alcohols from the syngas as fuel or gasoline additives have good application prospects.

Many patents have disclosed catalysts and process technologies for synthesizing low-carbon mixed alcohols. More representative catalysts and techniques are as follows, for example, the Octamix process (European Patent EP-0034338-A2, U.S. Patent US-4513100, US- No. 4031123 and US-2327066); the IFP process with Cu-Co as the main component of the catalyst developed by the French Petroleum Research Institute (US-4122110, US-4291126); jointly developed by Dow Chemical Company and United Carbon Corporation The Sygmol process with _MoS2 as the main component of the catalyst (US Patent No. US-4675344 and European Patent No. EP-0235886). These patented technologies have their own characteristics. Among them, the content of C ₂₊ alcohols in the products of Sygmol and IFP processes is relatively high; the Octamix process adopts a low-pressure method, which has high space-time yield and low water content, and its product distribution is expected to be further improved. However, the composition of the catalysts used in these patented technologies is relatively complicated, the preparation process is relatively cumbersome, and some of them have harsh reaction conditions. On the other hand, there are also patents disclosing the use of rhodium-containing catalysts to manufacture C from synthesis gas _Alcohol technology, such as Chinese Patent No. 96112685 provides a rhodium-containing Li(Na)/Rh-Mn-Fe/ _SiO catalyzer, The total selectivity of oxygenates such as methanol, ethanol, acetaldehyde, and propanol can reach more than 90%, but the CO conversion rate is very low (less than about 6-7%), the catalyst preparation process is cumbersome, and rhodium metal is expensive. Although the modified Cu-Zn-Al catalyst developed by Lurgi Company has good activity to generate low-carbon alcohols, the selectivity of C ₂₊ alcohols is not high, and the reaction conditions are relatively harsh.

The present invention prepares (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-MgO composite oxide catalyst through the composite of MgO and CuO-ZnO-Al ₂ O ₃ -ZrO ₂ , and traditional CuO-ZnO-Al ₂ O Compared with the ₃ -ZrO ₂ catalyst, the catalyst of the present invention has a higher space-time yield of C ₂ -C ₅ mixed alcohols.

Contents of the invention

The object of the present invention is to provide a catalyst for producing C ₁ -C ₅ mixed alcohols from synthesis gas and a preparation method thereof. The (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-MgO catalyst prepared by this method has a higher C ₁ -C ₅ mixed alcohol space-time recovery than the traditional CuO-ZnO-Al ₂ O ₃ -ZrO ₂ catalyst. The yield, especially the space-time yield of C ₂ -C ₅ mixed alcohols has been greatly improved.

The (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-MgO catalyst and its preparation method for producing C ₁ -C ₅ mixed alcohols from synthesis gas provided by the present invention are characterized in that: mechanical mixing or co-precipitation Composite MgO and CuO-ZnO-Al ₂ O ₃ -ZrO ₂ , and roast at a certain temperature to obtain (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-MgO composite oxide. Using the (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-MgO prepared by the method of the present invention as a catalyst and using synthesis gas as a raw material, C ₁ to C ₅ mixed alcohols can be efficiently produced under conditions of heating and pressure .

In the (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-MgO catalyst prepared by the method of the present invention, the mass percentage of CuO-ZnO-Al ₂ O ₃ -ZrO ₂ and MgO is (CuO-ZnO-Al ₂ O ₃ - ZrO ₂ ): 85-35%, MgO: 15-65%, and the composition (molar ratio) of CuO-ZnO-Al ₂ O ₃ -ZrO ₂ is Cu: 40-50%, Zn: 30-40%, Al : 5-15%, Zr: 5-15%.

The specific process of preparing (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-MgO catalyst by co-precipitation method includes:

(1) Preparation of raw material salt and precipitant solution

Prepare Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , Al(NO ₃ ) ₃ , ZrO(NO ₃ ) ₂ and Mg(NO ₃ ) ₂ metal salt solutions in different proportions, prepare KOH and K ₂ CO ₃ Mix the aqueous precipitant solution.

(2) Precipitation, aging and post-treatment process

The metal salt aqueous solution and the precipitant aqueous solution are simultaneously added dropwise to produce precipitation, then aged, filtered, washed and dried, and finally the powder is roasted in a muffle furnace to obtain (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-MgO.

The specific process of preparing (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-MgO catalyst by mechanical mixing method includes:

(1) Preparation of CuO-ZnO-Al ₂ O ₃ -ZrO ₂

Prepare Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , Al(NO ₃ ) ₃ and ZrO(NO ₃ ) ₂ metal salt solutions, prepare KOH and K ₂ CO ₃ mixed precipitant aqueous solution, mix metal salt solution and precipitation The aqueous solution of the agent is added dropwise at the same time to produce precipitation, then aged, filtered, washed and dried, and finally the powder is roasted in a muffle furnace to obtain CuO-ZnO-Al ₂ O ₃ -ZrO ₂ .

(2) Preparation of MgO

MgO can be prepared from Mg(NO ₃ ) ₂ by traditional precipitation method; commercial MgO can also be used directly.

(3) Composites of CuO-ZnO-Al ₂ O ₃ -ZrO ₂ and MgO

Weigh CuO-ZnO-Al ₂ O ₃ -ZrO ₂ and MgO in a certain proportion, perform mechanical mixing, and then roast in a muffle furnace to obtain (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-MgO.

The invention uses synthesis gas as raw material gas to prepare C ₁ -C ₅ mixed alcohol under the conditions of heating and pressurizing and the presence of (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-MgO catalyst. The synthesis gas used in the present invention is a mixed gas with the ratio of carbon monoxide and hydrogen = 1:1. Carry out above-mentioned reaction by the method of the present invention, carry out under heating. The reaction temperature is generally 250-350° C.; the above-mentioned reaction is carried out according to the method of the present invention under increased pressure, and the pressure of the synthesis gas is generally 6 MPa.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the embodiments.

Example 1

(1) Preparation of 50% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-50% MgO catalyst (co-precipitation method)

Weigh 1.41g Cu(NO ₃ ) ₂ , 1.74g Zn(NO ₃ ) ₂ , 0.49g Al(NO ₃ ) ₃ , 0.35g ZrO(NO ₃ ) ₂ and 6.67g Mg(NO ₃ ) ₂ into 100ml deionized water to make a metal salt solution; weigh 3.37g KOH and 4.14g K ₂ CO ₃ into 120ml deionized water to make a precipitant solution. In addition, measure 80ml of deionized water into the flask, place it in a water bath at a constant temperature of 65°C, and add the metal salt solution and the precipitant solution dropwise to the deionized water in the above flask at the same time under stirring, and adjust and maintain the precipitation process. pH=9. After the dropwise addition, continue to stir the mother liquor for 1 hour, then filter, wash the filter cake 3 times with hot deionized water at 80°C, then wash 2 times with normal temperature deionized water, and finally wash 2 times with ethanol, and put the filter cake in an oven Dry at 110°C for 12 hours, and then place in a muffle furnace and bake at 400°C in air for 3 hours to obtain a 50% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-50% MgO catalyst.

(2) In the presence of 50% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-50% MgO, the reaction of synthesis gas to C ₁ -C ₅ mixed alcohols is carried out. The reaction of synthesis gas to C ₁ -C ₅ mixed alcohols It was carried out in a stainless steel tube lined with a quartz tube (10mm inner diameter) micro-fixed-bed flow reactor. Weigh 0.5 g of 50% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-50% MgO catalyst and put it in the middle of the quartz tube, and fill the upper and lower ends of the catalyst bed with quartz wool. Before the reaction, the catalyst was raised from room temperature to 270°C at 1°C/min in H ₂ /N ₂ mixed gas (V _N2 /V _H2 =4/1), and reduced at 270°C for 4 hours. Then adjust to the reaction temperature of 250°C, switch to raw material gas (V _H2 /V _CO = 1/1), and react under 6MPa pressure, the raw material gas flow rate is controlled by a mass flow meter (space velocity is 6000mL/g/h) , the reaction pressure is controlled by a pressure stabilizing valve and a back pressure valve, and the temperature of the catalyst bed is measured and controlled by a thermocouple and a temperature controller. The gas at the outlet of the reaction tube is decompressed and the product is detected and analyzed online by an online gas chromatograph at a temperature of 150°C. After the sampling and analysis of the reaction at 250°C, the temperature of the catalyst bed was raised to 300°C for the reaction, and the gas at the outlet of the reaction tube was also detected and analyzed by online gas chromatography. After the sampling and analysis of the reaction at 300°C, the temperature of the catalyst bed was raised to 350°C for the reaction, and the gas at the outlet of the reaction tube was also detected and analyzed by online gas chromatography. The CO conversion rate and the space-time yield of alcohol ether products were calculated according to the chromatographic analysis results, and the reaction results are listed in Table 1.

Example 2

(1) Preparation of 35% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-65% MgO catalyst (co-precipitation method)

Weigh 0.87g Cu(NO ₃ ) ₂ , 0.833g Zn(NO ₃ ) ₂ , 0.3g Al(NO ₃ ) ₃ , 0.21g ZrO(NO ₃ ) ₂ and 8.21g Mg(NO ₃ ) ₂ into 100ml deionized water to make a metal salt solution; weigh 3.37g KOH and 4.14g K ₂ CO ₃ into 120ml deionized water to make a precipitant solution. In addition, measure 80ml of deionized water into the flask, place it in a water bath at a constant temperature of 65°C, and add the metal salt solution and the precipitant solution dropwise to the deionized water in the above flask at the same time under stirring, and adjust and maintain the precipitation process. pH=9. Other subsequent steps are the same as those in Example 1, that is, a 35% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-65% MgO catalyst is obtained.

(2) In the presence of 35% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-65% MgO, the reaction for producing C ₁ -C ₅ mixed alcohols from synthesis gas is the same as in Example 1 (2). The reaction results are listed in Table 2.

Example 3

(1) Preparation of 70% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-30% MgO catalyst (co-precipitation method)

Weigh 2.283g Cu(NO ₃ ) ₂ , 2.186g Zn(NO ₃ ) ₂ , 0.788gAl(NO ₃ ) ₃ , 0.561g ZrO(NO ₃ ) ₂ and 4.872g Mg(NO ₃ ) ₂ and add them into 100ml deionized water , to make a metal salt solution; weigh 3.37g KOH and 4.14g K ₂ CO ₃ and add it to 120ml deionized water to make an aqueous solution of a precipitant. In addition, measure 80ml of deionized water into the flask, place it in a water bath at a constant temperature of 65°C, and add the metal salt solution and the precipitant solution dropwise to the deionized water in the above flask at the same time under stirring, and adjust and maintain the precipitation process. pH=9. Other subsequent steps are the same as those in Example 1, that is, 70% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-30% MgO is obtained.

(2) In the presence of 70% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-30% MgO, the reaction for producing C ₁ -C ₅ mixed alcohols from synthesis gas is the same as in Example 1 (2). The reaction results are listed in Table 3.

Example 4

(1) Preparation of 85% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-15% MgO catalyst (co-precipitation method)

Weigh 3.153g Cu(NO ₃ ) ₂ , 3.019g Zn(NO ₃ ) ₂ , 1.088gAl(NO ₃ ) ₃ , 0.775g ZrO(NO ₃ ) ₂ and 2.821gMg(NO ₃ ) ₂ and add them into 100ml deionized water , to make a metal salt solution; weigh 3.37g KOH and 4.14g K ₂ CO ₃ and add it to 120ml deionized water to make an aqueous solution of a precipitant. In addition, measure 80ml of deionized water into the flask, place it in a water bath at a constant temperature of 65°C, and add the metal salt solution and the precipitant solution dropwise to the deionized water in the above flask at the same time under stirring, and adjust and maintain the precipitation process. pH=9. The subsequent other steps are the same as in Example 1, that is, an 85% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-15% MgO catalyst is obtained.

(2) In the presence of 85% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-15% MgO, the reaction for producing C ₁ -C ₅ mixed alcohols from synthesis gas is the same as in Example 1 (2). The reaction results are listed in Table 4.

Example 5

(1) Preparation of 50% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-50% MgO (mechanical mixing) catalyst

Prepare CuO-ZnO-Al ₂ O ₃ -ZrO ₂ oxide first: weigh 4.35g Cu(NO ₃ ) ₂ , 4.05g Zn(NO ₃ ) ₂ , 1.50g Al(NO ₃ ) ₃ and 1.07g ZrO(NO ₃ ) ₂ was added to 100ml deionized water to make a metal salt aqueous solution; 3.37g KOH and 4.14g K ₂ CO ₃ were weighed and added to 120ml deionized water to make a precipitant aqueous solution. In addition, measure 80ml of deionized water into the flask, place it in a water bath at a constant temperature of 65°C, and add the metal salt solution and the precipitant solution dropwise to the deionized water in the above flask at the same time under stirring, and adjust and maintain the precipitation process. pH=7. Other subsequent steps are the same as in Example 1, namely to obtain CuO-ZnO-Al ₂ O ₃ -ZrO ₂ .

Composite of MgO and CuO-ZnO-Al ₂ O ₃ -ZrO ₂ : Weigh 1.00g of commercial reagent MgO (calcined at 400°C in air for 3 hours before use) and mix with 1.00g of CuO-ZnO-Al ₂ O ₃ -ZrO ₂ , Use ethanol as diluent, mechanically mix and stir for 10 hours, then evaporate the ethanol to dryness, put the solid in an oven and dry it at 110°C for 12 hours, then place it in a muffle furnace and roast it in air at 400°C for 3 hours to obtain 50% ( CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-50% MgO (mechanical mixing) catalyst.

(2) In the presence of 50% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-50% MgO (mechanical mixing), the reaction of synthesis gas to C ₁ -C ₅ mixed alcohols is carried out

Reaction operation is with embodiment 1 (2). The reaction results are listed in Table 5.

Comparative example 1

(1) Preparation of CuO-ZnO-Al ₂ O ₃ -ZrO ₂ catalyst

Weigh 4.35g Cu(NO ₃ ) ₂ , 4.05g Zn(NO ₃ ) ₂ , 1.50g Al(NO ₃ ) ₃ and 1.07g ZrO(NO ₃ ) ₂ and add them into 100ml deionized water to form a metal salt solution; Weigh 3.37g KOH and 4.14g K ₂ CO ₃ and add them into 120ml deionized water to form a precipitant aqueous solution. In addition, measure 80ml of deionized water into the flask, place it in a water bath at a constant temperature of 65°C, and add the metal salt solution and the precipitant solution dropwise to the deionized water in the above flask at the same time under stirring, and adjust and maintain the precipitation process. pH=7. Other subsequent steps are the same as in Example 1, namely to obtain a CuO-ZnO-Al ₂ O ₃ -ZrO ₂ catalyst.

(2) In the presence of CuO-ZnO-Al ₂ O ₃ -ZrO _{2 ,} the reaction of syngas to C ₁ -C ₅ mixed alcohols

Reaction operation is with embodiment 1 (2). The reaction results are listed in Table 6.

The reaction result of Table 1 Example 1 (50% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-50% MgO catalyst)

Note: The total alcohol ether product refers to the sum of dimethyl ether + methanol + C ₂ -C ₅ alcohol (the same below).

The reaction result of Table 2 Example 2 (35% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-65% MgO catalyst)

Table 3 Example 3 (70% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-30% MgO catalyst) reaction results

Table 4 Example 4 (85% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-15% MgO catalyst) reaction results

Table 5 Example 5 (mechanical mixing 50% (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ )-50% MgO catalyst) reaction results

The reaction result of Table 6 Comparative Example 1 (CuO-ZnO-Al ₂ O ₃ -ZrO ₂ catalyst)

Claims (6)

1. method from the synthesis gas preparation low carbon mixed alcohol catalyst, it is characterized in that: this method is by MgO and CuO-ZnO-Al ₂O ₃-ZrO ₂Compound (the CuO-ZnO-Al that makes ₂O ₃-ZrO ₂)-MgO composite oxides are with (CuO-ZnO-Al ₂O ₃-ZrO ₂)-MgO is catalyst, is unstripped gas with the synthesis gas, makes C under the condition of pressurization of heating ₁～C ₅Mixed alcohol.

2. method according to claim 1 is characterized in that: described at (CuO-ZnO-Al ₂O ₃-ZrO ₂In the)-MgO catalyst, CuO-ZnO-Al ₂O ₃-ZrO ₂With the mass percent of MgO be (CuO-ZnO-Al ₂O ₃-ZrO ₂): 85～35%, MgO:15～65%.

3. method according to claim 1 is characterized in that: described at CuO-ZnO-Al ₂O ₃-ZrO ₂In, the molar percentage of each metal is Cu:40～50%, Zn:30～40%, Al:5～15%, Zr:5～15%.

4. method according to claim 1 is characterized in that: MgO and CuO-ZnO-Al ₂O ₃-ZrO ₂Compound employing mechanical mixing or coprecipitation.

5. method according to claim 4 is characterized in that: adopt coprecipitation to prepare MgO and CuO-ZnO-Al ₂O ₃-ZrO ₂Compound the time, precipitating reagent adopts KOH and K ₂CO ₃Mixed aqueous solution, and KOH and K ₂CO ₃Mol ratio be 2/1～1/1.

6. method according to claim 4 is characterized in that: adopt mechanical mixing to prepare MgO and CuO-ZnO-Al ₂O ₃-ZrO ₂Compound the time, CuO-ZnO-Al ₂O ₃-ZrO ₂Make by the precipitation method earlier, mix by certain quality percentage and MgO again, and through 400 ℃ of roastings.