CN114797903B - Syngas-to-lower alcohol catalyst and preparation method and application thereof - Google Patents

Abstract

The invention relates to the field of catalysts, and discloses a catalyst for preparing low-carbon alcohol from synthesis gas, a preparation method of the catalyst and application of the catalyst in preparing low-carbon alcohol from synthesis gas. The catalyst contains an active component Co, mo, K, S and an auxiliary agent M, wherein M is at least one element selected from Mg, ca and La; based on the total amount of the catalyst, the Co content is 5.5-17wt%, the Mo content is 33-47wt%, the K content is 4-9wt%, the S content is 30-50wt%, and the M content is 0.05-0.9wt%, wherein the molar ratio of M to Mo is 0.005-0.09:1. the catalyst for preparing the low-carbon alcohol from the synthetic gas is used in the reaction for preparing the low-carbon alcohol from the synthetic gas, has high catalytic activity, and improves the selectivity of the total alcohol in the product and the space-time yield of the total alcohol.

Description

Syngas-to-lower alcohol catalyst and preparation method and application thereof

Technical field

The invention relates to the field of catalysts, specifically to a catalyst for producing lower alcohol from synthesis gas, a preparation method of the catalyst, and the application of the catalyst in producing lower alcohol from synthesis gas.

Background technique

Energy is the basis for human survival and civilization evolution, and our country is a country short of oil, little gas, and rich in coal. It is of great strategic significance to develop a modern coal chemical industry and develop clean and efficient coal conversion technology. Producing syngas (CO+H ₂ ) by coal gasification, and then catalytically converting the syngas to synthesize low-carbon alcohols can not only alleviate the current shortage of petroleum resources in China, but is also one of the most realistic and feasible ways to achieve efficient and clean conversion of coal resources. Low-carbon mixed alcohols can be used as gasoline additives, fuels, and as high value-added chemicals after separation.

Due to the complexity of the synthesis gas-to-lower alcohol reaction process and mechanism, the selectivity of the target product is low, while the selectivity of the by-products methanol and hydrocarbons is high. This reaction process requires the dissociative adsorption of CO to achieve carbon chain growth, and the non-dissociative adsorption of CO. When the carbon chain grows to a certain length, it is inserted to generate alcohol. The coordination and matching of these two reactions must be achieved to obtain More target products C ₂ OH-C ₆ OH. If the CO insertion ability is weak, more hydrocarbons will be obtained after carbon chain growth. If the carbon chain growth ability is weak, CO will be hydrogenated to generate more methanol. , resulting in low selectivity of the target product C ₂ ⁺ alcohol. Therefore, the design and development of catalysts with high selectivity and activity and excellent stability are key factors for this technological breakthrough.

_MoS2- based catalysts are considered to be one of the most promising catalyst systems for the synthesis of low-carbon alcohols due to their unique sulfur tolerance, high activity and alcohol selectivity, and long life. However, the current MoS2 _- based catalysts There are still problems such as low catalytic activity, low total alcohol selectivity, and low total alcohol space-time yield.

CN103459020A discloses a catalyst for converting synthesis gas into alcohol. The catalyst includes nickel, molybdenum, at least one metal selected from palladium, ruthenium, chromium, gold, zirconium and aluminum, and an alkali metal or alkali metal as a promoter. A combination of at least one of alkaline earth metals. Although this catalyst can improve the selectivity of C ₂ -C ₄ alcohols, the conversion rate is low and the total alcohol selectivity is low.

US4882360 discloses a catalyst for producing lower alcohols from synthesis gas and a preparation method thereof. The catalyst includes a first component of at least one of molybdenum and tungsten, a second component of at least one of Fe, Co, and Ni, a third component of an alkali metal or alkaline earth metal promoter, and a fourth component of other components. and carrier. When the reaction temperature is about 300°C, the reaction pressure is 10MPa, and the space velocity is 1000-2000h ^-1 , the catalyst can achieve a total alcohol selectivity of more than 70% in the product, CH ₃ OH/C ₂ ⁺ alcohol ( wt%)<0.5, but the space velocity used is low, resulting in low space-time yield of alcohol products.

Summary of the invention

The purpose of the present invention is to overcome the problems in the prior art of using MoS ₂ -based catalysts to produce low-carbon alcohols from synthesis gas, low total alcohol selectivity and low total alcohol space-time yield, and provide a catalyst for producing low-carbon alcohols from synthesis gas. and preparation methods and applications thereof.

In order to achieve the above object, the first aspect of the present invention provides a catalyst for preparing low-carbon alcohols from synthesis gas, the catalyst comprising active components Co, Mo, K, S and an additive M, wherein M is at least one element selected from Mg, Ca and La;

Based on the total amount of the catalyst, the content of Co is 5.5-17wt%, the content of Mo is 33-47wt%, the content of K is 4-9wt%, the content of S is 30-50wt%, and the content of M is 0.05-0.9wt%, where the molar ratio of M to Mo is 0.005-0.09:1.

A second aspect of the present invention provides a method for preparing a catalyst for preparing low-carbon alcohols from synthesis gas, the method comprising:

(1) Prepare ammonium thiomolybdate solution and a mixed solution containing cobalt salt and M salt;

(2) The ammonium thiomolybdate solution and the mixed solution are subjected to a co-precipitation reaction in the bottom liquid;

(3) The product obtained by the co-precipitation reaction is subjected to solid-liquid separation, and then the obtained solid is washed, dried, and roasted to obtain a precursor;

Wherein, the drying and roasting are performed under inert gas protection conditions;

(4) Mix the precursor with potassium carbonate, grind and tablet it to obtain the catalyst;

Wherein, M is selected from at least one element among Mg, Ca and La; the amounts of ammonium thiomolybdate, cobalt salt, M salt and potassium carbonate are such that the content of Co in the obtained catalyst is 5.5-17wt %, the content of Mo is 33-47wt%, the content of K is 4-9wt%, the content of S is 30-50wt%, and the content of M is 0.05-0.9wt%; the ammonium thiomolybdate and M salt are The dosage meets: the molar ratio of M to Mo is 0.005-0.09:1.

The third aspect of the present invention provides a catalyst for preparing low-carbon alcohols from synthesis gas prepared by the preparation method described above.

A fourth aspect of the present invention provides a use of the above-mentioned synthesis gas to prepare low-carbon alcohols catalyst in the preparation of low-carbon alcohols from synthesis gas.

Through the above technical solution, the synthesis gas to lower alcohol alcohol catalyst of the present invention is used in the synthesis gas to lower alcohol alcohol reaction, has high catalytic activity, and improves the selectivity of the total alcohol in the product and the space-time yield of the total alcohol.

Description of drawings

Figure 1 is an X-ray diffraction analysis (XRD) chart of the catalysts prepared in Examples 1-3 and Comparative Example 1.

Detailed ways

The endpoints of ranges and any values disclosed herein are not limited to the precise range or value, but these ranges or values are to be understood to include values approaching such ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges. These values The scope shall be deemed to be specifically disclosed herein.

The first aspect of the present invention provides a catalyst for producing lower alcohols from synthesis gas. The catalyst contains active components Co, Mo, K, S and an auxiliary agent M, wherein M is selected from at least one of Mg, Ca and La. element;

Based on the total amount of the catalyst, the content of Co is 5.5-17wt%, the content of Mo is 33-47wt%, the content of K is 4-9wt%, the content of S is 30-50wt%, and the content of M is 0.05-0.9wt%, where the molar ratio of M to Mo is 0.005-0.09:1.

In some specific embodiments of the present invention, the aforementioned catalyst compositions can achieve the purpose of the present invention. In order to further improve the activity of the catalyst, and further improve the selectivity of total alcohol in the product and the space-time yield of total alcohol, preferably, The total amount of the catalyst is the basis, the content of Co is 6.5-16wt%, the content of Mo is 35-45wt%, the content of K is 4.5-7wt%, the content of S is 35-45wt%, and the content of M is 0.08 -0.6wt%.

In some specific embodiments of the present invention, in the synthesis gas-to-lower alcohol catalyst of the present invention, Co, Mo and auxiliary agent M exist in the form of sulfide, and K exists in the form of K ₂ S ₃ O ₆ . The sulfides of Co and Mo exist in various forms, including composite metal sulfides (Co-MoS ₂ ) and independent metal sulfides (MoS ₂ , CoS ₂ and Co ₉ S ₈ ). Among them, CO dissociation adsorption, H ₂ dissociation adsorption and CH _x species formation reactions occur on the independent metal sulfide phase (CoS ₂ , Co ₉ S ₈ , MoS ₂ ). Under the reaction evaluation conditions, after about 100- At 200h, CoS ₂ gradually transformed into Co ₉ S ₈ , which is more favorable for the reaction; non-dissociative adsorption of CO, carbon chain growth and alcohol formation reactions occurred on the potassium-promoted composite metal sulfide phase (Co-MoS ₂ ).

In some specific embodiments of the present invention, an X-ray diffractometer (XRD) of model D/max-2600/pc purchased from Rigaku Company is used to perform phase analysis on the synthesis gas-to-lower alcohol catalyst of the present invention. In the X-ray diffraction analysis (XRD) chart, the characteristic peaks appearing at 2θ=19.0°, 23.9°, 24.7°, 24.9°, 26.5°, 28.1°, and 31.1° of the synthesis gas-to-lower alcohol catalyst of the present invention are consistent with The K ₂ S ₃ O ₆ standard card PDF-75-1479 is consistent, indicating that the K ₂ S ₃ O ₆ structure is formed in the synthesis gas to lower alcohol catalyst prepared in the present invention; and the synthesis gas prepared without adding the additive M However, the characteristic peaks of K ₂ S ₃ O ₆ did not appear in the lower alcohol production catalyst, and the K ₂ S ₃ O ₆ structure was not formed, indicating that the introduction of the additive M during the preparation process of the MoS _2- based catalyst can promote the adsorption of K ₂ on the catalyst. The formation of S ₃ O ₆ structure and K ₂ S ₃ O ₆ structure can stabilize the intermediate products of the reaction and change the electronic structure of the catalyst, making the activation of CO easier and reducing the hydrogenation activity of alkyl species. Assistant M The addition of Co-MoS ₂ is also beneficial to reducing the size of the Co-MoS active center and increasing the number of active centers per unit weight of the catalyst, thereby improving the catalytic activity of the catalyst, the selectivity of the total alcohol in the product and the space-time yield of alcohol.

In some specific embodiments of the present invention, if the molar ratio of the additive M to Mo is greater than 0.09, it will not only fail to improve the total alcohol selectivity and total alcohol space-time yield, but will also reduce the activity of the catalyst; if the additive If the molar ratio of additive M to Mo is less than 0.005, the content of M in the catalyst will be too low, which will not improve the total alcohol selectivity and total alcohol space-time yield. Therefore, only the molar ratio of additive M to Mo can be Only when the ratio is controlled within the range of 0.005-0.09:1 can the selectivity of total alcohol and the space-time yield of total alcohol be improved. In order to further improve the selectivity of total alcohol and the space-time yield of total alcohol, preferably, the molar ratio of assistant M to Mo is 0.008-0.06:1, more preferably 0.01-0.05:1.

In some specific embodiments of the present invention, in order to ensure an appropriate ratio between the two active centers (Co-MoS ₂ and MoS ₂ , CoS ₂ ), to improve the catalytic activity of the catalyst in the synthesis gas to lower alcohol reaction and For the selectivity of total alcohol in the product, preferably, the molar ratio of Co to Mo is 0.2-0.8:1, more preferably 0.3-0.7:1.

In some specific embodiments of the present invention, in order to promote the formation of sulfides of Co and Mo active metals, improve the catalytic activity of the catalyst and the selectivity of the total alcohol in the product, preferably, the molar ratio of S to Mo is 2-4 :1, more preferably 2.5-3.5:1.

A second aspect of the invention provides a method for preparing a catalyst for producing lower alcohols from synthesis gas, which method includes:

(1) Prepare ammonium thiomolybdate solution and a mixed solution containing cobalt salt and M salt;

(2) The ammonium thiomolybdate solution and the mixed solution are subjected to a co-precipitation reaction in the bottom liquid;

(3) The product obtained by the co-precipitation reaction is subjected to solid-liquid separation, and then the obtained solid is washed, dried, and roasted to obtain a precursor;

Wherein, the drying and roasting are performed under inert gas protection conditions;

(4) mixing the precursor with potassium carbonate, grinding and tableting to obtain the catalyst;

Wherein, M is selected from at least one element among Mg, Ca and La; the amounts of ammonium thiomolybdate, cobalt salt, M salt and potassium carbonate are such that the content of Co in the obtained catalyst is 5.5-17wt %, the content of Mo is 33-47wt%, the content of K is 4-9wt%, the content of S is 30-50wt%, and the content of M is 0.05-0.9wt%; the ammonium thiomolybdate and M salt are The dosage meets: the molar ratio of M to Mo is 0.005-0.09:1.

In some specific embodiments of the present invention, the amounts of ammonium thiomolybdate, cobalt salt, M salt and potassium carbonate can be selected according to the content and molar ratio of the aforementioned components, which will not be described again here.

In some specific embodiments of the present invention, the cobalt salt can be a water-soluble cobalt salt commonly used in the art, selected from water-soluble cobalt salts, and can be a commercial product. For example, the cobalt salt can be selected from the group consisting of water-soluble cobalt salts. From at least one of cobalt acetate, cobalt nitrate and cobalt sulfate.

In some specific embodiments of the present invention, the M salt can be a water-soluble M salt commonly used in the art, selected from water-soluble salts containing the M element, and can be a commercially available product. For example, the M salt can be selected from at least one of acetate, nitrate and sulfate containing the M element.

In some specific embodiments of the present invention, in step (1), the ammonium thiomolybdate solution can be prepared according to conventional methods. For example, the step of preparing the ammonium thiomolybdate solution can be: adding molybdic acid Ammonium and ammonium sulfide solution react at a temperature of 50-70°C for 0.2-4h.

In some specific embodiments of the present invention, in step (2), the bottom liquid can be used to obtain a predetermined ratio of catalyst precursor, and the precipitation reaction can also be maintained in the pH range of 4-6. In addition, it can also ensure When the mixed solution of ammonium thiomolybdate solution, cobalt salt, and M salt is dropped into the precipitation flask, it can precipitate uniformly at the set temperature. In order to further improve the selectivity of total alcohol in the product and the space-time yield of total alcohol, preferably, the bottom liquid is an acetic acid solution with a mass concentration of 20-40 wt%.

In some specific embodiments of the present invention, preferably, in step (2), the conditions of the coprecipitation reaction include: an aging temperature of 50-60° C. and an aging time of 0.5-12 h.

In some specific embodiments of the present invention, in step (3), conventional separation methods can be used to separate the solid from the solid-liquid separation. For example, filtration can be used to achieve solid-liquid separation.

In some specific embodiments of the present invention, the solid obtained by solid-liquid separation can be washed with deionized water, and then dried and calcined under the protection of inert gas to obtain the precursor. In order to prevent the catalyst from being violently oxidized and causing structural changes, the drying and calcining are both carried out in an inert atmosphere. The inert atmosphere can be an atmosphere formed by various existing gases that do not react with reactants and products, for example, it can be an atmosphere formed by gases such as nitrogen and/or helium and/or argon.

In some specific embodiments of the present invention, the drying conditions are not particularly limited, as long as the solvent attached to the product can be removed. For example, the drying conditions usually include: the drying temperature can be 40-120 ℃, preferably 70-110 ℃; drying time can be 2-25h, preferably 4-20h.

In some specific embodiments of the present invention, the roasting conditions are not particularly limited, as long as CoMoS ₄ can be decomposed into Co-MoS ₂ and the excess S is evaporated in the form of S element. For example, the roasting The conditions usually include: the calcination temperature can be 300-500°C, and the calcination time can be 0.3-6h. In order to avoid the Co-MoS ₂ active center particles being larger and reducing the activity, preferably, the roasting temperature is 350-400°C and the roasting time is 0.5-4h.

The third aspect of the present invention provides a synthesis gas-to-lower alcohol catalyst prepared by the above-mentioned preparation method. The catalyst contains active components Co, Mo, K, S and auxiliary agent M, wherein M is selected from at least one element selected from Mg, Ca and La;

Based on the total amount of the catalyst, the content of Co is 5.5-17wt%, the content of Mo is 33-47wt%, the content of K is 4-9wt%, the content of S is 30-50wt%, and the content of M is 0.05-0.9wt%, where the molar ratio of M to Mo is 0.005-0.09:1.

In some specific embodiments of the present invention, preferably, based on the total amount of the catalyst, the content of Co is 6.5-16wt%, the content of Mo is 35-45wt%, the content of K is 4.5-7wt%, the content of S is 35-45wt%, and the content of M is 0.08-0.6wt%.

In some embodiments of the present invention, preferably, the molar ratio of M to Mo is 0.008-0.06:1, more preferably 0.01-0.05:1.

In some specific embodiments of the present invention, preferably, the molar ratio of Co to Mo is 0.2-0.8:1, more preferably 0.3-0.7:1.

In some embodiments of the present invention, preferably, the molar ratio of S to Mo is 2-4:1, more preferably 2.5-3.5:1.

In some embodiments of the invention, preferably, Co, Mo and M exist in the form of sulfide, and K exists in the form of K ₂ S ₃ O ₆ .

A fourth aspect of the present invention provides a use of the above-mentioned synthesis gas to prepare low-carbon alcohols catalyst in the preparation of low-carbon alcohols from synthesis gas.

In some specific embodiments of the present invention, the method of using the catalyst of the present invention to produce lower alcohols from synthesis gas may include: molding the catalyst of the present invention, loading it into a fixed bed reactor, and using the air in the reactor with The inert gas is replaced, and then the reactor is heated. When the temperature and pressure rise to the temperature and pressure required for the reaction, the reaction gas is introduced into the reactor for reaction, thereby producing low carbon alcohol. Among them, the reaction conditions include: pressure 7-10MPa, temperature 320-350°C, volume space velocity 2000-4000mL·g ^-1 ·h ^-1 , volume ratio of reaction gas H ₂ /CO = 0.8-1.2:1 . Wherein, the production of lower alcohol from synthesis gas can be carried out in a fixed bed or a fluidized bed, preferably in a fixed bed.

In the present invention, the pressure is gauge pressure.

The present invention will be described in detail through examples below, but it should be understood that the protection scope of the present invention is not limited by the examples.

In the following examples and comparative examples, the raw materials used are commercial products.

The molar (or weight) composition of the prepared syngas-to-lower alcohol catalyst component was analyzed and measured using an X-ray fluorescence spectrometer (XRF) model ZSX Primus II purchased from Rigaku Company, using Upside Radiation X-ray generation. Device, 4kW Rh target, test element category range is F-U, test area diameter is 30mm, test method is all-element semi-quantitative method;

The prepared synthesis gas to low-carbon alcohol catalyst was subjected to X-ray diffraction analysis using an X-ray diffractometer (XRD) of model D/max-2600/pc purchased from Rigaku Corporation;

The microstructure of the catalyst for preparing low-carbon alcohols from synthesis gas was observed and measured by a scanning electron microscope (SEM) of model Nova Nano SEM 450 purchased from FEI Company, with an acceleration voltage of 20kV-30kV, a resolution limit of about 1.2nm, and a magnification of 25-200K times.

The catalytic performance of the prepared synthesis gas-to-lower alcohol catalyst was evaluated through a four-channel reactor purchased from Altamira Company.

The reaction conditions include: pressure 8MPa, temperature 345°C, volume space velocity 3000mL·g ^-1 ·h ^-1 , and reaction gas volume ratio H ₂ /CO = 1/1.

The evaluation process includes: tableting and sieving the catalyst of the present invention to obtain particles of 20-40 mesh, using quartz sand to fix the catalyst in the constant temperature section of the reactor. The loading amount of the catalyst is 1.5 grams. After performing a leak test on the device, Replace the air in the reactor with the inert gas He gas 3-5 times, and then heat up the reactor. When the temperature and pressure rise to the temperature and pressure required for the reaction (345°C, 8MPa), 37.5mL ( Standard conditions) H ₂ and 37.5 mL of CO and 3.26 mL of N ₂ (internal standard gas) were passed into the reactor to carry out the reaction of synthesis gas to lower alcohol.

After the reaction, the gas tail gas passed through the cold trap for gas-liquid separation, and the tail gas was analyzed online using Agilent 7890 chromatography. Among them, H ₂ , CO, CH ₄ , and N ₂ were analyzed by TDX-01 carbon molecular sieve chromatography column, with He as The carrier gas is detected by TCD; C ₁ -C ₆ hydrocarbons (alkenes and alkanes) are analyzed through a modified Al ₂ O ₃ packed chromatographic column, using Ar as the carrier, and detected by FID. The remaining products were analyzed by offline chromatography Shimadzu GC-2010, and the liquid phase products were analyzed by two Porpak Q chromatographic columns, using TCD (water and methanol) and FID (C ₁ -C ₅ oxygenated compounds) detectors respectively.

CO conversion rate, total alcohol selectivity and C ₂ ⁺ alcohol selectivity are used as evaluation indicators for the performance of the syngas-to-lower alcohol catalyst. CO conversion rate (χCO), product selectivity ( Calculated based on the mol number of carbon, the carbon base selectivity is based on) and the total alcohol selectivity (S _ROH is calculated on the basis of the mol number of carbon, the carbon based selectivity is based on) are calculated by the following equations:

Among them, χCO represents the CO conversion rate; represents the product selectivity; S _ROH represents the total alcohol selectivity; F represents the number of moles of the substance, i represents the number of carbon atoms of the substance;/> Indicates the number of moles of CO at the inlet,/> Indicates the number of moles of CO at outlet.

Example 1

(1) 100 g of a 26.5 wt % ammonium molybdate solution was heated to 60° C., and then 206.5 g of a 20 wt % ammonium sulfide solution was added, and the mixture was reacted at 60° C. for 1 h to obtain an ammonium thiomolybdate solution; 13.2 g of cobalt acetate and 0.42 g of magnesium acetate were dissolved in 280 mL of deionized water to prepare a mixed solution;

(2) at a temperature of 55° C., the ammonium thiomolybdate solution and the mixed solution were added dropwise to a base solution (the base solution was a 30 wt % acetic acid solution) at the same speed to perform a coprecipitation reaction, and after aging at 55° C. for 1 h, a precipitate was obtained;

(3) After filtering and washing the precipitate, dry it at 90°C for 12 hours under the protection of nitrogen atmosphere, and then bake it at 400°C for 1 hour under the protection of nitrogen atmosphere to obtain the precursor;

(4) Mix 9g of precursor and 1g of K ₂ CO ₃ , grind and press into tablets. The prepared catalyst is marked as S1.

Among them, the molar ratio of Mg to Mo is 0.011:1; the molar ratio of Co to Mo is 0.35:1; the molar ratio of S to Mo is 2.7:1, the content of Mo is 42.43wt%, and the content of Co is 9.12wt%. , the content of Mg is 0.12wt%, the content of K is 5.66wt%, and the content of S is 38.33wt%.

Example 2

(1) Heat 100g of ammonium molybdate solution with a concentration of 26.5wt% to 60°C, then add 340.5g of ammonium sulfide solution with a concentration of 20wt%, and react at 65°C for 1 hour to obtain an ammonium thiomolybdate solution; add 30.5g Cobalt nitrate and 0.94g of lanthanum acetate were dissolved in 320mL of deionized water to prepare a mixed solution;

(2) At a temperature of 55°C, add the ammonium thiomolybdate solution and the mixed solution dropwise to the bottom liquid at the same speed (the bottom liquid is a 30wt% acetic acid solution) for co-precipitation reaction, and age at 55°C. After 2 hours, a precipitate was obtained;

(3) After filtering and washing the precipitate, dry it at 90°C for 12 hours under the protection of nitrogen atmosphere, and then bake it at 390°C for 1.5 hours under the protection of nitrogen atmosphere to obtain the precursor;

(4) Mix 9g of precursor and 1g of K ₂ CO ₃ , grind and press into tablets, and the prepared catalyst is marked as S2.

Among them, the molar ratio of La to Mo is 0.01:1; the molar ratio of Co to Mo is 0.7:1; the molar ratio of S to Mo is 3.4:1, the content of Mo is 34.86wt%, and the content of Co is 14.99wt%. , the content of La is 0.50wt%, the content of K is 5.66wt%, and the content of S is 39.65wt%.

Example 3

(1) Heat 100g of ammonium molybdate solution with a concentration of 26.5wt% to 55°C, then add 206.5g of ammonium sulfide solution with a concentration of 20wt%, and react at 55°C for 1 hour to obtain an ammonium thiomolybdate solution; add 18.9g Cobalt acetate and 0.87g of calcium sulfate were dissolved in 280mL of deionized water to prepare a mixed solution;

(2) At a temperature of 55°C, add the ammonium thiomolybdate solution and the mixed solution dropwise to the bottom liquid at the same speed (the bottom liquid is a 30wt% acetic acid solution) for co-precipitation reaction, and age at 55°C. After 1 hour, a precipitate was obtained;

(3) After filtering and washing the precipitate, dry it at 100°C for 8 hours under the protection of nitrogen atmosphere, and then bake it at 360°C for 4 hours under the protection of nitrogen atmosphere to obtain the precursor;

(4) 8.9 g of the precursor was mixed with 1.1 g of K ₂ CO ₃ , ground, and pressed into tablets. The resulting catalyst was designated as S3.

Among them, the molar ratio of Ca to Mo is 0.03:1; the molar ratio of Co to Mo is 0.5:1; the molar ratio of S to Mo is 3:1, the content of Mo is 38.32wt%, and the content of Co is 11.75wt% , the content of Ca is 0.48wt%, the content of K is 6.22wt%, and the content of S is 38.45wt%.

Example 4

According to the method of Example 1, the difference is that in step (1), the amount of magnesium acetate added is 2.3g, and the obtained catalyst is marked as S4.

Among them, the molar ratio of Mg to Mo is 0.06:1.

Example 5

According to the method of Example 1, the difference is that in step (1), the amount of magnesium acetate added is 3.4g, and the obtained catalyst is marked as S5.

Among them, the molar ratio of Mg to Mo is 0.09:1.

Example 6

The method of Example 1 was followed, except that in step (1), the amount of cobalt acetate added was 30.2 g, and the resulting catalyst was denoted as S6.

Among them, the molar ratio of Co to Mo is 0.8:1.

Example 7

According to the method of Example 1, the difference is that in step (1), the amount of cobalt acetate added is 5.7g, and the obtained catalyst is marked as S7.

Among them, the molar ratio of Co to Mo is 0.15:1.

Example 8

The method of Example 1 was followed, except that in step (1), the amount of ammonium sulfide solution added was 175.9 g, and the catalyst obtained was recorded as S8.

Among them, the molar ratio of S to Mo is 2.3:1.

Example 9

The method of Example 1 was followed, except that in step (1), the amount of ammonium sulfide solution added was 321.2g, and the catalyst obtained was recorded as S9.

Among them, the molar ratio of S to Mo is 4.2:1.

Example 10

The method of Example 1 was followed, except that in step (1), the amount of magnesium acetate added was 3.5 g, and the catalyst obtained was recorded as S10.

Among them, the content of Mg is 0.9wt%.

Example 11

According to the method of Example 1, the difference is that in step (4), the amount of potassium carbonate added is 1.70g, and the obtained catalyst is marked as S11.

Wherein, the content of K is 9wt%.

Example 12

The method of Example 1 is followed, except that in step (1), 13.2 g of cobalt acetate, 0.22 g of magnesium acetate and 0.12 g of lanthanum acetate are dissolved in 280 mL of deionized water to prepare a mixed solution. The resulting catalyst is recorded as S12.

Among them, the content of Mg is 0.06wt%, and the content of La is 0.06wt%.

Example 13

The method of Example 1 was followed, except that in step (1), 13.2 g of cobalt acetate, 0.13 g of calcium acetate and 0.12 g of lanthanum acetate were dissolved in 280 mL of deionized water to prepare a mixed solution. The resulting catalyst was recorded as S13.

Among them, the content of Ca is 0.06wt%, and the content of La is 0.06wt%.

Example 14

According to the method of Example 1, the difference is that in step (1), 13.2g of cobalt acetate, 0.22g of magnesium acetate, 0.13g of calcium acetate, and 0.12g of lanthanum acetate were dissolved in 280 mL of deionized water to prepare into a mixed solution, and the resulting catalyst was marked as S14.

Among them, the content of Mg is 0.06wt%, the content of Ca is 0.06wt%, and the content of La is 0.06wt%.

Comparative example 1

The method of Example 1 is followed, except that the mixed solution in step (1) does not contain magnesium acetate. The obtained catalyst is denoted as D1.

Comparative Example 2

According to the method of Example 1, the difference is that in step (1), the amount of magnesium acetate added is 3.7g, and the obtained catalyst is marked as D2. Among them, the content of Mg is 1wt%.

Comparative example 3

The method of Example 2 was followed, except that in step (1), the amount of lanthanum acetate added was 2.3 g, and the resulting catalyst was recorded as D3, wherein the content of La was 1.2 wt%.

Comparative example 4

According to the method of Example 1, the difference is that in step (1), the amount of magnesium acetate added is 0.11g, and the obtained catalyst is marked as D4. Among them, the molar ratio of Mg to Mo is 0.003:1.

The syngas-produced lower alcohol catalysts prepared in Examples 1-3 and Comparative Example 1 were subjected to X-ray diffraction analysis (XRD), and the results are shown in Figure 1.

In Figure 1, S1 is the X-ray diffraction curve of the synthesis gas-to-lower alcohol catalyst prepared in Example 1, S2 is the X-ray diffraction curve of the synthesis gas-to-lower alcohol catalyst prepared in Example 2, and S3 is the X-ray diffraction curve of the synthesis gas-to-lower alcohol catalyst prepared in Example 3, and D1 is the X-ray diffraction curve of the synthesis gas-to-lower alcohol catalyst prepared in Comparative Example 1. It can be seen from Figure 1 that the synthesis gas-to-lower alcohol catalysts prepared in Examples 1-3 (corresponding to curves S1, S2, and S3 in the figure respectively) have characteristic peaks 2θ=19.0°, 23.9°, 24.7°, and 24.9 °, 26.5°, 28.1°, and 31.1° are consistent with the K ₂ S ₃ O ₆ standard card PDF-75-1479, indicating that the K ₂ S ₃ O ₆ structure is formed in the synthesis gas-to-lower alcohol catalyst prepared in the present invention; However, in the synthesis gas-to-lower alcohol catalyst prepared in Comparative Example 1 (corresponding to curve D1 in the figure), the characteristic peak of K ₂ S ₃ O ₆ does not appear, and the K ₂ S ₃ O ₆ structure is not formed, indicating that the additive M The addition can promote the formation of the K ₂ S ₃ O ₆ structure on the catalyst. The K ₂ S ₃ O ₆ structure can stabilize the reaction intermediates and change the electronic structure of the catalyst, making it easier to activate CO and reducing the addition of alkyl species. Hydrogen activity, thereby improving the catalytic activity of the catalyst, the selectivity of the total alcohol in the product, and the space-time yield of the total alcohol. The remaining examples are similar and the results are not shown.

The catalytic performance of the synthesis gas-to-lower alcohol catalysts prepared in Examples 1-14 and Comparative Examples 1-4 was evaluated, and the results are shown in Table 1.

Table 1

It can be seen from the results in Table 1 that the catalyst containing the additive M has better catalytic activity, selectivity for total alcohol in the product and space-time yield of total alcohol than the catalyst without the additive M.

In particular, it can be seen from the comparison of the evaluation results of Examples 1-5 that by controlling the molar ratio of the auxiliary agent M to Mo within the preferred range of the present invention, the activity, total alcohol selectivity and total alcohol space-time yield of the prepared catalyst are further improved;

Comparing the evaluation results of Example 1 and Examples 6-7, it can be seen that controlling the molar ratio of Co to Mo within the preferred range of the present invention can further improve the catalytic activity of the catalyst, the selectivity of the total alcohol in the product and the total alcohol space-time yield;

Comparing the evaluation results of Example 1 and Examples 8-9, it can be seen that controlling the molar ratio of S to Mo within the preferred range of the present invention can further improve the catalytic activity of the catalyst, the selectivity of the total alcohol in the product and the total alcohol space-time yield;

Comparing the evaluation results of Example 1 and Example 10, it can be seen that the content of the additive M is within the preferred range of the present invention, which can further improve the catalytic activity of the catalyst, the selectivity of the total alcohol in the product, and the space-time yield of the total alcohol. ;

Comparing the evaluation results of Example 1 and Example 11, it can be seen that the content of K is within the preferred range of the present invention, which can further improve the catalytic activity of the catalyst, the selectivity of the total alcohol in the product, and the space-time yield of the total alcohol;

Comparing the evaluation results of Examples 1-3 and 12-14, it can be seen that when the additive M is two or three kinds of Mg, Ca and La, it can also further improve the activity of the catalyst and the content of the total alcohol in the product. Selectivity and space-time yield of total alcohols.

Comparing the evaluation results of Example 1 and Comparative Example 1, it can be seen that the catalyst without additive M cannot improve the catalytic activity of the catalyst, the selectivity of the total alcohol in the product, and the space-time yield of the total alcohol.

Comparing the evaluation results of Example 1 and Comparative Examples 2-3, it can be seen that only when the content of the promoter M in the catalyst is within the range limited by the present invention can the catalytic activity of the catalyst be improved, and the selectivity and total alcohol selectivity of the total alcohol in the product can be improved. If the content of additive M is too high, it will not only fail to improve the catalytic performance, but will also reduce the catalytic activity of the catalyst, the selectivity of the total alcohol in the product, and the space-time yield of the total alcohol.

Comparing the evaluation results of Example 1 and Comparative Example 4, it can be seen that catalysts whose molar ratio of additives M and Mo are not within the limited range of the present invention are useful for improving the catalytic activity of the catalyst, the selectivity of the total alcohol in the product, and the total alcohol space and time. The effect on yield is not obvious.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the disclosed content of the present invention. All belong to the protection scope of the present invention.

Claims (28)

1. A catalyst for preparing low-carbon alcohols from synthesis gas, characterized in that the catalyst contains active components Co, Mo, K, S and an additive M, wherein M is at least one element selected from Mg, Ca and La; Based on the total amount of the catalyst, the content of Co is 5.5-17wt%, the content of Mo is 33-47wt%, the content of K is 4-9wt%, the content of S is 30-50wt%, and the content of M is 0.05-0.9wt%, where the molar ratio of M to Mo is 0.005-0.09:1; K exists in the form of K ₂ S ₃ O ₆ . 2. The catalyst according to claim 1, wherein, based on the total amount of the catalyst, the content of Co is 6.5-16wt%, the content of Mo is 35-45wt%, the content of K is 4.5-7wt%, the content of S is 35-45wt%, and the content of M is 0.08-0.6wt%. 3. The catalyst according to claim 2, wherein the molar ratio of M to Mo is 0.008-0.06:1. 4. The catalyst according to claim 3, wherein the molar ratio of M to Mo is 0.01-0.05:1. 5. The catalyst according to claim 2, wherein the molar ratio of Co to Mo is 0.2-0.8:1. 6. The catalyst according to claim 5, wherein the molar ratio of Co to Mo is 0.3-0.7:1. The catalyst according to claim 2 , wherein the molar ratio of S to Mo is 2-4:1. 8. The catalyst according to claim 7, wherein the molar ratio of S to Mo is 2.5-3.5:1. 9. The catalyst of claim 2, wherein Co, Mo and M are present in the form of sulfide. 10. A method for preparing a catalyst for producing lower alcohols from synthesis gas, characterized in that the method includes: (1) preparing an ammonium thiomolybdate solution and a mixed solution containing a cobalt salt and an M salt; (2) The ammonium thiomolybdate solution and the mixed solution are subjected to a co-precipitation reaction in a bottom liquid; the bottom liquid is an acetic acid solution with a mass concentration of 20-40wt%; (3) The product obtained by the co-precipitation reaction is subjected to solid-liquid separation, and then the obtained solid is washed, dried, and roasted to obtain a precursor; Wherein, the drying and roasting are performed under inert gas protection conditions; (4) Mix the precursor with potassium carbonate, grind and tablet it to obtain the catalyst; Wherein, M is selected from at least one element among Mg, Ca and La; the amounts of ammonium thiomolybdate, cobalt salt, M salt and potassium carbonate are such that the content of Co in the obtained catalyst is 5.5-17wt %, the content of Mo is 33-47wt%, the content of K is 4-9wt%, the content of S is 30-50wt%, and the content of M is 0.05-0.9wt%; the ammonium thiomolybdate and M salt are The dosage satisfies: the molar ratio of M to Mo is 0.005-0.09:1; K exists in the form of K ₂ S ₃ O ₆ . 11. The preparation method according to claim 10, wherein the dosage of the ammonium thiomolybdate and M salt satisfies: the molar ratio of M to Mo is 0.008-0.06:1. 12. The preparation method according to claim 11, wherein the amounts of the ammonium thiomolybdate and the M salt satisfy that the molar ratio of M to Mo is 0.01-0.05:1. 13. The preparation method according to claim 10, wherein the amounts of ammonium thiomolybdate and cobalt salt satisfy: the molar ratio of Co to Mo is 0.2-0.8:1. 14. The preparation method according to claim 13, wherein the amounts of ammonium thiomolybdate and cobalt salt satisfy: the molar ratio of Co to Mo is 0.3-0.7:1. 15. The preparation method according to claim 10, wherein the amount of ammonium thiomolybdate is such that the molar ratio of S to Mo in the obtained catalyst is 2-4:1. 16. The preparation method according to claim 15, wherein the amount of ammonium thiomolybdate is such that the molar ratio of S to Mo in the obtained catalyst is 2.5-3.5:1. 17. The preparation method according to claim 10, wherein the amounts of the ammonium thiomolybdate, the cobalt salt, the M salt and the potassium carbonate are such that the catalyst contains 6.5-16wt% Co, 35-45wt% Mo, 4.5-7wt% K, 35-45wt% S and 0.08-0.6wt% M. 18. The preparation method according to any one of claims 10-17, wherein in step (1), the step of preparing ammonium thiomolybdate solution is specifically: mixing ammonium molybdate and ammonium sulfide solution at 50-70 React at ℃ temperature for 0.2-4h. 19. The preparation method according to any one of claims 10 to 17, wherein the cobalt salt is selected from water-soluble cobalt salts; the M salt is selected from water-soluble salts containing M element. 20. The preparation method according to claim 19, wherein the cobalt salt is selected from at least one of cobalt acetate, cobalt nitrate and cobalt sulfate. 21. The preparation method according to claim 19, wherein the M salt is selected from at least one of acetate, nitrate and sulfate containing M element. 22. The preparation method according to any one of claims 10-17, wherein the conditions of the co-precipitation reaction include: aging temperature is 50-60°C, and aging time is 0.5-12h. 23. The preparation method according to claim 22, wherein the drying conditions include: a temperature of 40-120°C and a time of 2-25 hours. 24. The preparation method according to claim 23, wherein the drying conditions include: a temperature of 70-110°C and a time of 4-20 hours. 25. The preparation method according to claim 22, wherein the roasting conditions include: a temperature of 300-500°C and a time of 0.3-6h. 26. The preparation method according to claim 25, wherein the roasting conditions include: a temperature of 350-400°C and a time of 0.5-4h. 27. A synthesis gas-to-lower alcohol catalyst prepared by the preparation method according to any one of claims 10 to 26. 28. Application of the synthesis gas to lower alcohol catalyst as claimed in any one of claims 1 to 9 and 27 in synthesis gas to lower alcohol.