CN108014816A - A kind of preparation method and application of CO hydrogenation synthesis mixing primary alconol coproduction alkene catalyst - Google Patents

Abstract

The invention provides a preparation method and application of a catalyst for CO hydrogenation to synthesize mixed primary alcohols and co-produce olefins. The general form of the catalyst is Co‑Mn‑X/AC, the carrier is activated carbon, the active component is Co‑Co ₂ C double active center composed of Co and Co ₂ C generated in the reaction process, the main additive is Mn, and X is One or more of Ce, Zn, Cu, La. Wherein, the content of Co is 1-30wt%, the content of Mn is 0.01-10wt%, and the content of auxiliary agent X is 0-10wt%. The catalyst provided by the invention can improve the selectivity of olefins and _C2 or more mixed primary alcohols in Fischer-Tropsch synthesis products, so that the total mass fraction of olefins and alcohols in the product is greater than 50wt%, which is conducive to the further production of alcohols, ethers, aldehydes , carboxylic acid and other high value-added chemicals and fine chemical products such as detergents, plasticizers and surfactants.

Description

A kind of preparation method and application of CO hydrogenation synthesis mixed primary alcohol coproduction olefin catalyst

technical field

The invention relates to a preparation method and application of a catalyst for CO hydrogenation to synthesize mixed primary alcohols and co-produce olefins. Specifically, the catalyst is in the form of Co-Mn-X/AC, which is an activated carbon-supported Co-Co ₂ C dual-active center catalyst, with Mn as the main additive, and auxiliary additives such as Ce, Cu, Zn, and La To improve the selectivity of olefins and mixed primary alcohols in the product.

Background technique

Using the Fischer-Tropsch (FT) synthesis method to produce olefins, alcohols, ethers, aldehydes, acids and other high-value chemicals using synthesis gas (CO/H ₂ ) in one step has become an important direction in the chemical industry in recent years. Specifically, C ₂ -C ₄ low-carbon olefins are important raw materials in the chemical industry, and can be used to produce chemicals such as polyethylene and polypropylene, and have a broad market space. Alkenes with a carbon number greater than or equal to 5 can be converted into corresponding alcohols, ethers, aldehydes, acids, halides and other fine chemicals through hydroformylation and other means, which have high added value. In addition, primary alcohols with a carbon number greater than or equal to 2 have unique and excellent properties and are widely used in many fields of the national economy. Among them, C ₂ -C ₅ alcohols can be used as excellent fuel additives to improve combustion efficiency, C ₆ -C ₁₁ higher alcohols can be used to produce plasticizers, and C ₁₂ -C ₁₈ higher alcohols can be used to produce surfactants. It is estimated that the market price of high-carbon primary alcohol is 10,000-20,000 yuan/ton, and the annual demand is about 13 million tons, with a growth rate of about 3%.

At present, the methods for industrially synthesizing low-carbon olefins mainly include methanol-to-olefins (MTO) and petroleum cracking. High-carbon olefins are mainly derived from the polymerization of low-carbon olefins. Therefore, starting from syngas, the one-step preparation of olefins has the shortest technical route and better economic benefits. The main methods for the synthesis of mixed primary alcohols are Ziegler method and olefin hydroformylation method. The Ziegler method uses ethylene as the raw material and triethylaluminum as the catalyst to achieve carbon chain growth, and then undergoes oxidation, hydrolysis and separation processes to obtain C ₆ -C ₁₆ straight-chain even-numbered primary alcohols. However, this method has a long process flow, complex technology, great difficulty in development, large catalyst consumption and poor safety. The olefin hydroformylation method is that under the action of Rh-based or Co-based catalysts, olefins are hydroformylated with a mixture of CO and _H2 to form aldehydes, and the aldehydes are then hydrogenated to produce corresponding alcohols. However, the process of this method is long, and the catalyst is expensive and easy to lose. Therefore, there is an urgent need to develop new technologies for the production of mixed primary alcohols with simple processes, mild reaction conditions, readily available raw materials and wide sources.

Mixed alcohols (C ₁ -C ₆ ) can be directly synthesized in one step by CO hydrogenation, and this method has the advantage of simple process. The US4775696 patent discloses a method for synthesizing low-carbon mixed alcohols from synthesis gas, and the catalyst is a Mo, W or Re-based catalyst. US4752622 and US4882630 patents provide methods for synthesizing low-carbon mixed alcohols with synthesis gas as raw material gas, using Mo and W-based catalysts modulated by Fe, Co and Ni additives, and adding alkali metals or alkaline earth metals. US6753353 discloses that nano-MoS ₂ or W ₂ C is used as a catalyst to catalyze the hydrogenation of CO to synthesize low-carbon mixed alcohols. The US8048933 patent discloses a method for producing low-carbon mixed alcohols using synthesis gas as a raw material. The catalyst used is Mo ₂ C, and Ni and/or Na are added as additives to improve the performance of the catalyst. CN01130481 discloses a Mn-Ni-K- _MoS2 catalyst. The Mn element is introduced into the preparation of the _MoS2- based catalyst, so that the activity of the catalyst to catalyze the synthesis of alcohol is significantly improved, and at the same time, the selectivity of alcohols above _C2 is improved. CN200610097869 provides a catalyst for synthesizing low-carbon alcohols from syngas and its preparation method, the main components of the catalyst are CuO, ZnO, Cr ₂ O ₃ , Al ₂ O ₃ and an appropriate amount of other additives (V, Mo, Mn, Mg, Ce), with higher CO conversion and higher selectivity to alcohols above _C2 . However, the carbon number of the mixed alcohols prepared by one-step CO hydrogenation is relatively low, generally C ₁ -C ₆ , and it is basically impossible to obtain high-carbon alcohols above C ₆ with high added value, and methanol with low added value has a larger proportion , reaching more than 40%, which restricts the economy of this technology.

The Dalian Institute of Chemical Physics, Chinese Academy of Sciences has developed a catalyst for preparing higher alcohols above _C6 through Fischer-Tropsch synthesis, wherein US 7670985 and CN101310856 disclose that the catalyst system is a Co-based catalyst supported by activated carbon. Under its catalytic action, CO Hydrogenation can directly synthesize high-carbon mixed primary alcohols. The selectivity of C ₂ -C ₁₈ alcohols in liquid products is as high as 60%, and the distribution of methanol in alcohols only accounts for about 2-4%. However, in addition to alcohols, the CO hydrogenation reaction products of the above catalysts also contain a large amount of alkanes, and the content of high value-added olefins is relatively low. Therefore, further optimization of the catalyst is needed.

Contents of the invention

The purpose of the present invention is to develop a catalyst that simultaneously increases the content of mixed primary alcohols and olefins in the Fischer-Tropsch synthesis product, so that the total mass fraction of mixed primary alcohols and olefins in the product reaches more than 50 wt%, in order to start from synthesis gas and produce alcohol, alcohol, and olefins in one step. High value-added chemicals such as ethers, aldehydes, and carboxylic acids.

In order to achieve the above goals, the technical solution adopted in the present invention specifically includes:

A catalyst for synthesizing olefins and mixed primary alcohols by CO hydrogenation is characterized in that the catalyst is in the form of Co-Mn-X/AC. Among them, the active component of the catalyst is a Co-Co ₂ C double active center composed of Co and Co ₂ C generated in the reaction process, the main additive is Mn, and the X additive is one of Ce, Cu, Zn, La or Several, the carrier is activated carbon. The olefin is an olefin compound with 2 to 30 carbons, and the mixed primary alcohol is a primary alcohol compound with 2 to 30 carbons.

For the above catalyst, the content of Co element in the active component is 1-30 wt% of the catalyst weight, the content of Mn is 0.01-10 wt% of the catalyst weight, and the content of auxiliary agent X is 0-10 wt% of the catalyst weight. The carrier is apricot kernel activated carbon or coconut shell activated carbon, the particle size of the activated carbon is 40μm-2cm, the specific surface area is 100-1500m ² /g, the average pore diameter is 0.1-20nm, and the pore volume is 0.1-2.5mL/g.

Above-mentioned catalyst preparation method comprises the following steps:

(1) Activated carbon raw material is first boiled and washed with deionized water;

(2) After impregnating the active carbon carrier with the soluble salt of the active component and the auxiliary agent or the aqueous acid solution, dry it under the air condition of 323～353K for 8～48 hours to prepare the semi-dry base catalyst;

(3) The semi-dry catalyst is roasted for 4-100 hours at a temperature of 353-700K and a space velocity of 100-5000h ^-1 under a nitrogen or argon atmosphere to prepare a dry catalyst;

(4) The dry-based catalyst is reduced for 2-100 hours in a hydrogen-containing atmosphere with a hydrogen content of 10-100%, a temperature of 473-873K, a pressure of 0-1.0 MPa, and a space velocity of 100-5000 h ^-1 to prepare an activated catalyst.

(5) The activated catalyst needs to be pretreated by H ₂ /CO mixed gas to achieve stable activity and selectivity. The H ₂ /CO molar ratio in the mixed gas is 0.5-4.0, and the pre-treatment temperature is 433-563K. The pressure is 0-6MPa, the space velocity is 100-10000h ^-1 , and the treatment time is 1-96 hours.

The catalyst mentioned above can be applied to both fixed-bed reactor and slurry-bed reactor. When applied to a fixed bed reactor, the above (3) (4) (5) steps are carried out in situ in the fixed bed reactor; when applied to a slurry bed reactor, (3) (4) steps are performed in the fluidized bed reactor After completion, the catalyst is transferred to a slurry bed reactor for step (5). Inert gas delivery should be used for catalyst transfer.

The preferred reaction conditions for the catalyst to catalyze CO hydrogenation to synthesize olefins and mixed primary alcohols are temperature 383-525K, pressure 0-8MPa, space velocity 100-6000h ^-1 , H ₂ /CO molar ratio 0.5-4.0.

In the CO hydrogenation reaction product of the above catalyst, the total mass of olefins accounts for no less than 30 wt%, the total mass of mixed primary alcohols accounts for no less than 20 wt%, and the total mass of olefins and mixed primary alcohols The proportion in the product is not less than 50wt%.

Compared with the prior art, the present invention has the following advantages:

By using the catalyst provided by the invention, the yield of mixed primary alcohols and olefins in the synthetic product can be increased simultaneously, and the proportion of the total mass in the product is not less than 50 wt%.

The Co-Co ₂ C catalyst provided by the present invention utilizes the noble metal-like properties of Co ₂ C to realize the functions of CO adsorption and carbon chain insertion, without using noble metals, and the catalyst price is reduced, which is beneficial to industrial mass production.

The catalyst provided by the invention has a carrier of activated carbon, which does not react with the loaded Co to form refractory substances such as cobalt silicate and cobalt aluminate during the catalyst activation and reaction process, which is beneficial to improving the reduction degree of Co and improving the life of the catalyst.

The beneficial effects of the present invention are:

On the basis of maintaining its high selectivity of mixed primary alcohols, the selectivity of olefins is greatly improved, and the olefins produced can be further converted into chemicals such as alcohols through hydroformylation, which improves the comprehensive value of CO hydrogenation products .

Detailed ways

The present invention will be further described below in conjunction with the examples and attached tables, without any limitation to the present invention.

Example 1

Prepare 10Co0.3Mn0.2Zn/AC catalyst, labeled as Cat1.

Coconut shell activated carbon with a specific surface area of 960m ² /g, an average pore diameter of 3.8nm, and a pore volume of 0.6mL/g was selected as the carrier, which was repeatedly washed in deionized water at 90°C for 20 times, and dried at 393K for 20 hours to obtain purified Activated carbon carrier.

Dissolve 4.94g of cobalt nitrate hexahydrate, 0.091g of zinc nitrate hexahydrate and 0.094g of manganese acetate in 10g of water to prepare an impregnation solution. Use the impregnating liquid to impregnate 8.95g of activated carbon carrier at room temperature 298K, and then dry it in the shade for about 10 hours. After there is no flowable water on the surface of the catalyst, place it in a 313K oven and dry it for 24 hours. After taking it out, in nitrogen, gradually raise the temperature to 573K and roast for 20 hours. , take it out and put it into a fixed bed reactor with a diameter of 6mm, the filling volume is 2mL, and the space velocity is 2000h ^-1 . The catalyst was gradually heated up to 673K for reduction in hydrogen for 20 hours, cooled down to 423K, switched to synthesis gas (H ₂ /CO=2:1), pressure 2 MPa, and heated up to 493K for FT reaction. After being stable for 12 hours, samples were taken every 24 hours to analyze the concentration of each component in the tail gas and the yield of liquid phase products. The results obtained are listed in Appendix Table 1.

Example 2

Preparation of 15Co0.3Mn3Cu/AC catalyst, labeled as Cat2.

Dissolve 7.41g of cobalt nitrate hexahydrate, 1.14g of copper nitrate trihydrate and 0.094g of manganese acetate in 10g of water to prepare an impregnation solution. Use this impregnation solution to impregnate 8.17g of activated carbon carrier at room temperature 298K, dry in the shade for about 10 hours, and place it in a 313K oven to dry for 24 hours after there is no flowable moisture on the surface of the catalyst. hour, take it out and put it into a fixed-bed reactor with a diameter of 6mm, the filling volume is 2ml, and the space velocity is 2000h ^-1 . The catalyst was gradually heated up to 673K for reduction in hydrogen for 20 hours, cooled down to 423K, switched to synthesis gas (H ₂ /CO=2:1), pressure 2 MPa, and heated up to 493K for FT reaction. After being stable for 12 hours, samples were taken every 24 hours to analyze the concentration of each component in the tail gas and the yield of liquid phase products. The results obtained are listed in Appendix Table 1.

Example 3

Preparation of 10Co0.5Mn1Ce0.1La/AC catalyst, marked as Cat3.

Dissolve 4.94g of cobalt nitrate hexahydrate, 0.99g of cerium nitrate, 0.03g of lanthanum nitrate hexahydrate and 0.157g of manganese acetate in 10 grams of water to prepare an impregnation solution. Use this impregnating solution to impregnate 8.84g of activated carbon carrier at room temperature 298K and then dry it in the shade for about 10 hours. After there is no flowable moisture on the surface of the catalyst, place it in a 313K oven and dry it for 24 hours. hour, take it out and put it into a fixed-bed reactor with a diameter of 6mm, the filling volume is 2mL, and the space velocity is 2000h ^-1 . The catalyst was gradually heated up to 673K for reduction in hydrogen for 20 hours, cooled down to 423K, switched to synthesis gas (H ₂ /CO=2:1), pressure 2 MPa, and heated up to 493K for FT reaction. After being stable for 12 hours, samples were taken every 24 hours to analyze the concentration of each component in the tail gas and the yield of liquid phase products. The results obtained are listed in Appendix Table 1.

Example 4

Preparation of 10Co2Mn0.2Zn2Cu/AC catalyst, marked as Cat4.

Dissolve 4.94g of cobalt nitrate hexahydrate, 0.091g of zinc nitrate hexahydrate, 0.76g of copper nitrate trihydrate and 0.629g of manganese acetate in 10g of water to prepare an impregnation solution. Use this impregnating solution to impregnate 8.6g of activated carbon carrier at room temperature 298K and then dry it in the shade for about 10 hours. After there is no flowable moisture on the surface of the catalyst, place it in a 313K oven and dry it for 24 hours. hour, take it out and put it into a fixed-bed reactor with a diameter of 6mm, the filling volume is 2mL, and the space velocity is 2000h ^-1 . The catalyst was gradually heated up to 673K for reduction in hydrogen for 20 hours, cooled down to 423K, switched to synthesis gas (H ₂ /CO=2:1), pressure 2 MPa, and heated up to 493K for FT reaction. After being stable for 12 hours, samples were taken every 24 hours to analyze the concentration of each component in the tail gas and the yield of liquid phase products. The results obtained are listed in Appendix Table 1.

Example 5

Preparation of 10Co7Mn7Cu1Ce/AC catalyst labeled as Cat5.

Dissolve 4.94g of cobalt nitrate hexahydrate, 2.66g of copper nitrate trihydrate, 0.31g of cerium nitrate hexahydrate and 2.20g of manganese acetate in 10g of water to prepare an impregnation solution. Use this impregnating solution to impregnate 7.50g of activated carbon carrier at room temperature 298K and then dry it in the shade for about 10 hours. After there is no flowable moisture on the surface of the catalyst, place it in a 313K oven and dry it for 24 hours. hour, take it out and put it into a fixed-bed reactor with a diameter of 6mm, the filling volume is 2mL, and the space velocity is 2000h ^-1 . The catalyst was gradually heated up to 673K for reduction in hydrogen for 20 hours, cooled down to 423K, switched to synthesis gas (H ₂ /CO=2:1), pressure 2 MPa, and heated up to 493K for FT reaction. After being stable for 12 hours, samples were taken every 24 hours to analyze the concentration of each component in the tail gas and the yield of liquid phase products. The results obtained are listed in Appendix Table 1.

Example 6

Preparation of 10Co5Mn2Zn1Ce/AC catalyst, labeled as Cat6.

Dissolve 4.94g of cobalt nitrate hexahydrate, 0.091g of zinc nitrate hexahydrate, 0.31g of cerium nitrate hexahydrate and 1.57g of manganese acetate in 10g of water to prepare an impregnation solution. Use this impregnating solution to impregnate 8.40g of activated carbon carrier at room temperature 298K and then dry it in the shade for about 10 hours. After there is no flowable moisture on the surface of the catalyst, place it in a 313K oven and dry it for 24 hours. hour, take it out and put it into a fixed-bed reactor with a diameter of 6mm, the filling volume is 2mL, and the space velocity is 2000h ^-1 . The catalyst was gradually heated up to 673K for reduction in hydrogen for 20 hours, cooled down to 423K, switched to synthesis gas (H ₂ /CO=2:1), pressure 2 MPa, and heated up to 493K for FT reaction. After being stable for 12 hours, samples were taken every 24 hours to analyze the concentration of each component in the tail gas and the yield of liquid phase products. The results obtained are listed in Appendix Table 1.

Embodiment 7～8

Apricot kernel activated carbon is selected as the carrier, the specific surface area of the carrier is 912m ² /g, the average pore diameter is 3.5nm, and the pore volume is 0.43mL/g. It is repeatedly washed in boiling deionized water for 20 times, and dried at 393K for 20 hours to obtain the purified activated carbon carrier.

Prepare and evaluate 10Co5Mn2Zn1Ce/AC catalyst according to the method similar to Example 4, marked as Cat7, and the obtained results are listed in Attached Table 1.

Prepare and evaluate 10Co2Mn0.2Zn2Cu/AC catalyst according to the method similar to Example 6, marked as Cat8, and the obtained results are listed in Attached Table 1.

Comparative example 1

The formula and method provided by the patent CN201210292413 were used instead to prepare the catalyst, and a similar method was used to evaluate its reaction and compare with the examples. The results obtained are listed in Appendix Table 1.

Comparative example 1: 15Co0.1Al/AC1

Comparative example 2

Compared with the Fe ₁₀₀ A _a B _b C _c O _x catalyst reported in patent CN201210225885, the results are listed in Table 1.

Comparative example 2: 20% Fe ₁₀₀ Mn ₅₀ Mg ₅ K ₅ O _x +80% (10% TiO ₂ +90% α-Al ₂ O ₃ ).

Table 1

Performance of CO Hydrogenation Synthesis of Mixed Primary Alcohols and Olefins over Co-Mn-X/AC Catalyst

From the comparative results, the catalyst provided by the present invention has further improved the selectivity of olefins in the product on the basis of maintaining a higher selectivity of mixed primary alcohols; The catalyst provided by the patent can simultaneously produce a large amount of mixed primary alcohols, which has higher atom economy and added value.

Claims (10)

1. A catalyst for CO hydrogenation synthesis of mixed primary alcohols co-producing olefins, characterized in that, The catalyst is in the form of Co-Mn-X/AC, in which the active component of the catalyst is Co-Co ₂ C double active center composed of Co and Co ₂ C generated during the reaction, Mn is the main auxiliary agent, X auxiliary agent It is one or more of Ce, Cu, Zn, La, and the carrier is activated carbon. 2. according to the described catalyst of claim 1, it is characterized in that, The olefins in the product are olefins with 2 to 30 carbons, and the mixed primary alcohols are primary alcohols with 2 to 30 carbons. 3. according to the described catalyst of claim 1, it is characterized in that, Calculated as metal Co, the content of Co in the active component is 1-30 wt% of the weight of the catalyst. 4. according to the described catalyst of claim 1, it is characterized in that, The Mn content is 0.01-10 wt% of the catalyst weight, and the auxiliary agent X content is 0-10 wt% of the catalyst weight. 5. according to the described catalyst of claim 1, it is characterized in that, The carrier is apricot kernel activated carbon or coconut shell activated carbon, the particle size of the activated carbon is 40μm-2cm, the specific surface area is 100-1500m ² /g, the average pore diameter is 0.1-20nm, and the pore volume is 0.1-2.5mL/g. 6. a preparation method of the described catalyst of claim 1, is characterized in that, comprises the following steps: (1) Activated carbon raw material is first boiled and washed with deionized water; (2) After impregnating the active carbon carrier with an aqueous solution of active component Co and a soluble salt of an auxiliary agent or an acid, dry it under 323-353K air conditions for 8-48 hours to prepare a semi-dry catalyst; (3) The semi-dry catalyst is roasted for 4-100 hours at a temperature of 353-700K and a space velocity of 100-5000h ^-1 under a nitrogen or argon atmosphere to prepare a dry catalyst; (4) The dry-based catalyst is reduced for 2-100 hours in a hydrogen-containing atmosphere with a hydrogen content of 10-100%, a temperature of 473-873K, a pressure of 0-1.0 MPa, and a space velocity of 100-5000 h ^-1 to prepare an activated catalyst; (5) The activated catalyst needs to be pretreated by H ₂ /CO mixed gas to achieve stable activity and selectivity. The H ₂ /CO molar ratio in the mixed gas is 0.5-4.0, and the pre-treatment temperature is 433-563K. The pressure is 0-6MPa, the space velocity is 100-10000h ^-1 , and the treatment time is 1-96 hours. 7. according to the preparation method described in claim 6, it is characterized in that, The catalyst can be applied to both fixed bed reactor and slurry bed reactor; When applied to a fixed bed reactor, the steps of (3)(4)(5) in claim 6 are carried out in situ in the fixed bed reactor; When applied to a slurry bed reactor, steps (3) and (4) are performed in a fluidized bed reactor, and after completion, the catalyst is transferred to a slurry bed reactor to perform step (5). 8. the application of a kind of catalyst described in claim 1, is characterized in that, The catalyst catalyzes FT synthesis of olefins and mixed primary alcohols under the conditions of a temperature of 383-525K, a pressure of 0-8 MPa, and a molar ratio of H ₂ /CO of 0.5-4.0. 9. Use according to claim 8, characterized in that The proportion of the total mass of olefins in the product is not less than 30wt%. 10. Use according to claim 8, characterized in that The proportion of the total mass of mixed primary alcohols in the product is not less than 20wt%.