WO2022166084A1

WO2022166084A1 - Preparation method for and use of solvent coordination metal catalyst

Info

Publication number: WO2022166084A1
Application number: PCT/CN2021/103443
Authority: WO
Inventors: 林鹿; 陈高峰; 曾宪海; 孙勇; 唐兴; 雷廷宙
Original assignee: 厦门大学
Priority date: 2021-02-04
Filing date: 2021-06-30
Publication date: 2022-08-11
Also published as: CN112844446A; CN112844446B

Abstract

The present invention belongs to the technical field of energy conversion and utilization, and specifically relates to a preparation method for and the use of a catalyst for preparing a lower alcohol from synthesis gas (CO+H2) of coal/biomass, etc. The catalyst takes a mesoporous material as a carrier. Metal ions are induced to enter the interior of a carrier pore channel by means of coordination between a polyhydroxy solvent ligand and the metal ions, and the metal ions are close to each other on the atomic scale. Under a high-temperature inert atmosphere, amorphous carbon generated by pyrolysis of the solvent ligand can reduce a metal in a high-valence state into active nanoparticles in situ. The pore channels of the mesoporous material and the amorphous carbon jointly exert a synchronous confinement effect, so as to effectively inhibit agglomeration and sintering of metal particles, and obtain nanoscale, high-activity, and high-dispersion active metal particles. Using the catalyst of the present invention can solve the past problems of a low CO conversion rate, poor stability of the catalyst, a wide product carbon number distribution, and especially, poor ethanol selectivity, during the process of preparing a lower alcohol from coal-based or biomass-based synthesis gas.

Description

A kind of preparation method and application of solvent coordination metal catalyst

technical field

The invention belongs to the technical field of energy conversion and utilization, and in particular relates to a preparation method and application of a catalyst for preparing low-carbon alcohol from coal-based or biomass-based synthesis gas (CO+H ₂ ).

Background technique

The reduction of crude oil reserves and the aggravation of environmental pollution have stimulated a research upsurge in the clean and efficient conversion of fossil energy and the development and utilization of renewable energy. Direct catalytic conversion of coal-based/biomass-based synthesis gas (CO+H ₂ ) to prepare low-carbon alcohols (C ₂₊ alcohols) is the choice for the clean conversion and utilization of coal and biomass. Low-carbon alcohols can further synthesize high-value chemicals, pharmaceuticals, plasticizers, lubricants, detergents, especially when used as fuels or fuel additives, and have excellent qualities such as high octane number and low pollutant emissions. It is mixed with gasoline to form an oil-alcohol hybrid fuel. In the process of preparing low-carbon alcohols from synthesis gas, there are many elementary reactions, the product system is complex, and the by-products include alkanes, low-carbon olefins, _CO2 , etc. Yield has become the technical bottleneck of large-scale industrial production in the low-carbon alcohol industry. Among them, the research and development of high-activity and high-stability catalysts is the focus and difficulty of research.

In the coal-based/biomass-based synthesis gas preparation system for low-carbon alcohols, CuCo-based catalysts are currently the most popular due to their abundant reserves, low price, mild reaction conditions, high CO hydrogenation activity and low-carbon alcohol selectivity, and strong carbon chain growth ability. Catalysts with industrial application prospects. Mechanism level: the bridge-adsorbed CO molecule dissociates and adsorbs on the Co ⁰ active site, the dissociated C ^* is directly hydrogenated to obtain CH _y ^* , the CC is coupled and then hydrogenated to obtain C _x H _y ^* , and the Cu ⁰ The linear adsorption of CO occurs on the active site to generate non-dissociated CO ^* , and C _x H _y ^* migrates to the Cu ⁰ active site and undergoes an insertion reaction with CO ^* to generate lower alcohols after hydrogenation. Therefore, the synergistic effect of Cu and Co is crucial for the synthesis of low-carbon alcohols, and studies have shown that the closer the active centers of Cu and Co are, the better the synergistic catalysis can be exerted. Therefore, the development of highly dispersed and intimate CuCo dual-active catalysts can effectively promote the synthesis of low-carbon alcohols towards industrialization.

In the prior art, Cao A et al. (Cao A, Liu G, Wang L, Liu J, Yue Y, Zhang L, Liu Y. Growing layered double hydroxides on CNTs and their catalytic performance for higher alcohol synthesis from syngas. J Mater Sci, 2016, 51: 5216-5231.) reported that CuCo catalysts were supported on carbon nanotubes by a co-precipitation method using layered double hydroxides as precursors. The raw materials used are Cu(NO ₃ ) ₂ .3H ₂ O, Co(NO ₃ ) ₂ .6H ₂ O, Al(NO ₃ ) ₃ .9H ₂ O, NaOH, Na ₂ CO ₃ and carbon nanotubes, and Commercially purchased expensive carbon nanotubes still need to be calcined at high temperature (350 °C) in the air for 2 hours to remove amorphous carbon, and then refluxed in a boiling solution of concentrated nitric acid and concentrated sulfuric acid at 100 °C for 4 hours, followed by deionized water. Finally, it was dried at 60° C. overnight to obtain the treated carbon nanotube carrier. The preparation method is also more complicated, requiring a Cu/Co/Al solution with strict molar concentration ratio (A[Cu ²⁺ ]+[Co ²⁺ ]+[Al ³⁺ ]=0.01M), and NaOH (0.04M) , Na ₂ CO ₃ (0.01M) mixed solution B, the mixing of A and B solution needs to maintain a strict alkaline system with pH=9.5. The CO conversion rate was 45.4% in the catalytic lower alcohol synthesis reaction, the yield of lower alcohol was 28.6%, and the catalyst stability was tested for 192 hours.

Therefore, the catalyst system of the prior art has the defects of low CO conversion rate, poor catalyst stability, wide product carbon number distribution, especially poor ethanol selectivity, etc. It is necessary to further develop solvent formulations with high CO hydrogenation activity and low carbon alcohol selectivity. metal catalyst.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the existing catalyst system, and cleverly design a solvent-coordinated metal catalyst with high CO hydrogenation activity and low carbon alcohol selectivity.

The invention provides a solvent-coordinated metal catalyst, which is characterized in that the catalyst uses a mesoporous material as a carrier, and is coordinated by a polyhydroxyl solvent and impregnated to reduce the active metal in situ, and the simultaneous confinement effect is in the pores of the mesoporous material. Confined growth of active nanoparticles in the channel; wherein, the mesoporous material is selected from SBA-15, KIT-6 or MCM-41; the active metals are Cu and M, and M is selected from Co, Fe, Ni, Mn , Mo, or Nb, preferably Co; the polyhydroxy solvent ligand is selected from ethylene glycol, 1,2-propanediol, 1,4-butanediol, or glycerol.

The mesoporous material can be prepared by a known method or obtained by commercial purchase.

In a specific embodiment, the weight percent composition of the catalyst is Cu: 1-30%, M: 1-30%, and the rest is a carrier, preferably, the weight percent composition of the catalyst is Cu: 7-13% , M: 7-13%, the rest are carriers.

Preferably, the carrier has a specific surface area of 200-900 m ² /g and an average pore size of 4-12 nm.

The present invention provides a method for preparing the above solvent-coordinated metal catalyst, which is characterized in that, using the mesoporous material as a carrier, a solvent-coordination impregnation method is used to confine the growth of Cu and M components in the pores of the mesoporous material, and after drying, The catalyst is obtained by pyrolysis in an inert atmosphere.

Preferably, the confined growth of Cu and M nanoparticles in the pores is performed by using metal ions corresponding to Cu and M to coordinate with a polyhydroxy solvent, so that Cu and M are close to each other at the atomic level.

In a specific embodiment, the immersion time is 12-24 h; the ratio of the metal ions corresponding to Cu and M is 3/1-1/3 (molar ratio).

More specifically, the metal ions corresponding to Cu and M are in the form of nitrates.

In a specific embodiment, the drying is vacuum drying at 100-150°C for 10-36h; the inert atmosphere is pyrolyzed under an inert atmosphere at 350-650°C for 2-8h; preferably, the inert atmosphere refers to _N2 atmosphere.

At the same time, the present invention also provides the application of the above-mentioned solvent-coordinated metal catalyst in the preparation of low-carbon alcohol from coal-based or biomass-based synthesis gas.

The present invention has the following characteristics: the selected polyhydroxy coordination type solvent ligands can coordinate Cu ions and M ions at the same time to form metal systems that are close to each other at the atomic level; The amorphous carbon generated by the solution plays the role of in-situ reduction, eliminating the step of hydrogen reduction of metal oxides, simplifying the operation and saving energy; the amorphous carbon plays the role of synchronously confining metal nanoparticles, inhibiting the degradation of metal particles. Agglomeration and sintering to obtain highly dispersed nanoscale active metal particles. In addition, the catalyst carrier selected in the present invention adopts a mesoporous material with a high specific surface area (200-900 m ² /g) and an average pore diameter of 4-12 nm, and the relatively large pores are favorable for the coordination growth of solvent-coordinated metals in the pores. . The relatively large pores ensure high dispersion of active components and promote the diffusion of reactants and products in the pores, reducing mass transfer resistance.

Therefore, the catalyst of the present invention has a good application in the preparation of low-carbon alcohols from coal-based/biomass-based synthesis gas. Compared with the prior art, it has the following advantages: the catalyst of the present invention can solve the problem of low CO conversion rate, poor stability, and wide product carbon number distribution in the process of preparing low-carbon alcohol from coal-based/biomass-based synthesis gas in the past. Especially the problem of poor ethanol selectivity. Experiments show that the single-pass CO conversion rate of the catalyst of the present invention can be up to 82.4%; the water-gas shift activity on the catalyst is low, and the CO ₂ selectivity is lower than 3%; the distribution of low-carbon alcohols in the product is narrow, and the selectivity of C1-C3 alcohols is good. up to 97%. In addition, the catalyst of the invention has a controllable preparation process, good stability and low price, and has good industrial application prospects.

Description of drawings

Figure 1 is an X-ray diffraction pattern (XRD) of the catalyst in the present invention.

Figure 2 is a transmission electron microscope (TEM) and particle statistics diagram of the catalyst in the present invention.

Fig. 3 is the XRD comparison diagram of the catalyst prepared by direct carbonization under the inert atmosphere in the present invention and the catalyst obtained by carbonization and air roasting and then hydrogen reduction.

Fig. 4 is the XRD comparison diagram of the catalyst prepared by using the solvent ligand 1,2 propylene glycol in the present invention and the catalyst obtained by deionized water as the solvent.

Fig. 5 is the stability evaluation result of the catalyst of Example 2 of the present invention.

Fig. 6 is the GC spectrum of the lower alcohol of the product obtained in Example 2 of the present invention.

Figure 7 is the MS spectrum of the product ethanol obtained in Example 2 of the present invention.

Figure 8 is the MS spectrum of the product n-propanol obtained in Example 2 of the present invention.

Figure 9 is the MS spectrum of the product n-butanol obtained in Example 2 of the present invention.

Detailed ways

The technical solutions of the present invention are described below with specific embodiments, but the protection scope of the present invention is not limited thereto.

Example 1

The preparation steps of the solvent-coordinated metal catalyst of the present embodiment are as follows:

① Dissolve 2.0g triblock copolymer P123 in 12.0g ethanol at 40°C, add 2.0g dilute hydrochloric acid (0.2M), stir for 4h, add 4.16g tetraethyl orthosilicate, and continue stirring for 48h. Then crystallize in a 100°C hydrothermal kettle for 24h. The obtained material was calcined at 500°C for 6h in an air atmosphere to obtain SBA-15.

② Dissolve 1.5 g of copper nitrate (Cu(NO ₃ ) ₂ ·3H ₂ O) and 1.0 g of cobalt nitrate (Co(NO ₃ ) ₂ ·6H ₂ O) in 20 mL of ethylene glycol, and immerse the above solution into 3.0 g In SBA-15, the catalyst A was prepared by dipping for 20 h, vacuum drying at 120 °C for 24 h, and then calcining at 550 °C under _N2 atmosphere for 5 h.

The weight percent composition of catalyst A is as follows: Cu 13%, Co 7%, and the balance is SBA-15.

③ The synthesis reaction of low-carbon alcohol is carried out in a high-pressure fixed-bed reactor. The reaction conditions are: 260° C., 2.5MPa, 4.0L/g.cat.h, and the synthesis gas composition is V(H ₂ )/V(CO)/V( N ₂ )=60/30/10, and the catalyst amount is 0.4 g. In order to ensure the reliability of the steady-state operation data, analysis and sampling can be started after the catalyst runs for 24 hours. The reaction raw materials, gas products and liquid products are analyzed on an Agilent GC 7890B. The results are shown in Table 1.

Example 2

①SBA-15 was prepared in the same way as in Example 1.

② Dissolve 1.0 g of copper nitrate (Cu(NO ₃ ) ₂ ·3H ₂ O) and 2.6 g of cobalt nitrate (Co(NO ₃ ) ₂ ·6H ₂ O) in 25 mL of 1,2 propylene glycol, and immerse the above solution into 4.0 g of In SBA-15, immersion for 20 h, vacuum drying at 120 °C for 24 h, and then calcination at 550 °C for 5 h under N ₂ atmosphere to prepare the catalyst B.

The weight percent composition of catalyst B is as follows: Cu 7%, Co 13%, and the balance is SBA-15.

③ The synthesis reaction of low-carbon alcohol is carried out in a high-pressure fixed-bed reactor. The reaction conditions are: 270° C., 2.3MPa, 4.5L/g.cat.h, and the synthesis gas composition is V(H ₂ )/V(CO)/V( N ₂ )=60/30/10, and the catalyst amount is 0.5 g. In order to ensure the reliability of the steady-state operation data, analysis and sampling can be started after the catalyst runs for 24 hours. The reaction raw materials, gas products and liquid products are analyzed on an Agilent GC7890B. The results are shown in Table 1. Figures 6-9 show the GC-MS spectrum of the lower alcohol obtained in Example 2. Wherein, Fig. 6 is the GC spectrum of the product lower alcohol, Fig. 7 is the MS spectrum of ethanol, Fig. 8 is the MS spectrum of n-propanol, and Fig. 9 is the MS spectrum of n-butanol.

Example 3

①SBA-15 was prepared in the same way as in Example 1.

② Dissolve 1.9 g of copper nitrate (Cu(NO ₃ ) ₂ ·3H ₂ O) and 2.5 g of cobalt nitrate (Co(NO ₃ ) ₂ ·6H ₂ O) in 30 mL of 1,4 butanediol, and immerse the above solution into The catalyst C was prepared by immersing 5.0 g of SBA-15 for 24 h, vacuum drying at 130 °C for 24 h, and then calcining at 550 °C under N ₂ atmosphere for 5 h.

The weight percent composition of catalyst C is as follows: Cu 10%, Co 10%, and the balance is SBA-15.

③ The synthesis reaction of low-carbon alcohol is carried out in a high-pressure fixed-bed reactor. The reaction conditions are: 250° C., 2.6MPa, 4.3L/g.cat.h, and the synthesis gas composition is V(H ₂ )/V(CO)/V( N ₂ )=60/30/10, and the catalyst amount is 0.4 g. In order to ensure the reliability of the steady state operation data, analysis and sampling can be started after the catalyst runs for 24 hours. The reaction raw materials, gas products and liquid products are analyzed on an Agilent GC7890B. The results are shown in Table 1.

Example 4

①3.0g of P123 was dissolved in 80g of deionized water, 5.0g of concentrated hydrochloric acid (37wt%) was added, 3.0g of n-butanol and 6.4g of ethyl orthosilicate were added to the above solution system, and stirred for 24h. Then, it was crystallized at 100°C for 24h, the obtained material was washed and dried overnight, and calcined at 550°C for 6h in an air atmosphere to obtain KIT-6.

② Dissolve 1.1 g of copper nitrate (Cu(NO ₃ ) ₂ ·3H ₂ O) and 1.5 g of cobalt nitrate (Co(NO ₃ ) ₂ ·6H ₂ O) in 20 mL of 1,2 propylene glycol, and immerse the above solution to 3.0 g KIT-6, impregnated for 24 h, vacuum-dried at 120 °C for 24 h, and calcined at 550 °C for 5 h under N ₂ atmosphere to prepare the catalyst D.

The weight percent composition of catalyst D is as follows: Cu 10%, Co 10%, and the balance is KIT-6.

③ The synthesis reaction of low-carbon alcohol is carried out in a high-pressure fixed-bed reactor. The reaction conditions are: 240° C., 2.5MPa, 4.0L/g.cat.h, and the synthesis gas composition is V(H ₂ )/V(CO)/V( N ₂ )=60/30/10, and the catalyst amount is 0.5 g. In order to ensure the reliability of the steady state operation data, analysis and sampling can be started after the catalyst runs for 24 hours. The reaction raw materials, gas products and liquid products are analyzed on an Agilent GC7890B. The results are shown in Table 1.

Example 5

① KIT-6 was prepared in the same manner as in Example 4.

② 0.8 g of copper nitrate (Cu(NO ₃ ) ₂ ·3H ₂ O) and 1.5 g of cobalt nitrate (Co(NO ₃ ) ₂ ·6H ₂ O) were dissolved in 25 mL of glycerol, and the above solution was immersed in 2.5 g of KIT- In 6, immersion for 24h, vacuum drying at 140°C for 24h, and then calcination at 550°C for 6h under _N2 atmosphere to prepare the catalyst E.

The weight percent composition of catalyst E is as follows: Cu 8%, Co 12%, and the balance is KIT-6.

③ The synthesis reaction of low-carbon alcohol is carried out in a high-pressure fixed-bed reactor. The reaction conditions are: 230°C, 2.7MPa, 4.8L/g.cat.h, and the synthesis gas composition is V(H ₂ )/V(CO)/V( N ₂ )=60/30/10, and the catalyst amount is 0.6 g. In order to ensure the reliability of the steady state operation data, analysis and sampling can be started after the catalyst runs for 24 hours. The reaction raw materials, gas products and liquid products are analyzed on an Agilent GC7890B. The results are shown in Table 1.

Table 1 Catalyst performance evaluation results in Examples 1 to 5

Example 6

The catalysts of Examples 1-5 of the present invention were characterized by X-ray diffraction (XRD). XRD test method: test on Rigaku Ultima IV X-ray diffractometer, Cu Kα rays (λ=0.1543nm), test angle 10-80°, rate 10°/min; test angle 42.5-45.5°, rate 0.5°/ min, the results are shown in Figure 1. The diffraction peaks at 2θ=43.3, 50.5° and 74.3° in the XRD patterns of each example are assigned to Cu(111), Cu(200) and Cu(220) crystal planes, respectively (JCPDS 04-0836). FIG. 2 shows the transmission electron microscope (TEM) and particle statistics of the catalyst prepared in the embodiment of the present invention. The particle size calculated according to Scherrer's formula is about 5-6 nm, indicating that the CuCo nanoparticles are highly dispersed in the pores of the catalyst.

Example 7

Taking the catalyst prepared in Example 2 as an example, the catalyst life test was carried out. Reaction conditions: 270°C, 2.3MPa, 4.5L/g.cat.h, the synthesis gas composition is V(H ₂ )/V(CO)/V(N ₂ )=60/30/10, the amount of catalyst is 0.5g, The test time is 300h. The results are shown in Figure 5. The CO conversion and product selectivity distribution remained stable and did not change significantly during the reaction for more than 300 h. It shows that the catalyst of the present invention has excellent stability. This excellent stability is due to the simultaneous coordination of CuCo ions by polyhydroxy solvent ligands, and the confined growth of nano-scale, high-dispersion active particles in the pores of the mesoporous material, and The amorphous carbon generated by the pyrolysis of solvent ligands also plays an effective role in inhibiting the agglomeration of copper nanoparticles, thereby improving the stability of the catalyst.

Example 8

The reaction evaluation results of the representative part of the catalysts currently reported in the synthesis gas to prepare the low-carbon alcohol system are listed in Table 2. It can be seen that the CO conversion rate and the low-carbon alcohol yield of the catalyst prepared in Example 2 of the present invention both show outstanding performance.

Table 2 is compared with the evaluation results of catalyst performance reported in the literature

Among them, the references mentioned are:

[1] Dong X, Liang X, Li H, Lin G, Zhang P, Zhang H.Preparation and characterization of carbon nanotube-promoted Co-Cu catalyst for higher alchol synthesis from syngas.Catalysis Today,2009,147:158-165 .

[2]Cao A,Liu G,Wang L,Liu J,Yue Y,Zhang L,Liu Y.Growing layered double hydroxides on CNTs and their catalytic performance for higher alcohol synthesis from syngas.J Mater Sci,2016,51:5216 -5231.

[3]Niu T,Liu G,Chen Y,Yang J,Wu J,Cao Y,Liu Y.Hydrothermal synthesis of graphene-LaFeO ₃ composite supported with Cu-Co nanocatalyst for higher alcohol synthesis from syngas.Appl Surf Sci,2016 , 364:388-399.

[4] Chen G, Lei T, Wang Z, Liu S, He X, Guan Q, Xin X, Xu H. Preparation of higher alcohols by biomass-based syngas from wheat straw over CoCuK/ZrO2-SiO2 catalyst.Industrial Crops&Products, 2019, 131:54-61.

[5] Cao A, Liu G, Yue Y, Zhang L, Liu Y. Nanoparticles of Cu-Co alloy derived from layered double hydroxides and their catalytic performance for higher alcohol syntheis from syngas. RSC Advances, 2015, 5(72): 58804-58812.

[6] Li Z, Luo G, Chen T, Zeng Z, Guo S, Lv J, Huang S, Wang Y, Max X. Bimetallic CoCu catalyst derived from in-situ grown Cu-ZIF-67 encapsulated inside KIT-6 for higher alchol synthesis from syngas. Fuel, 2020, 278:118292-118301.

[7] Sun K, Wu Y, Tan M, Wang L, Yang G, Zhang M, Zhang W, Tan Y. Ethanol and higher alcohols synthesis from syngas over CuCoM (M=Fe, Cr, Ga ans Al) nanoplates derived from hydrotalcite-like precursors. Chemcatchem, 2019, 11:2695-2706.

[8] Xiang Y, Barbosa R, Li X, Kruse N. Ternary cobalt–copper–niobium catalysts for the selective CO hydrogenation to higher alcohols. ACS Catal 2015, 5:2929-2934.

[9] Xiang Y, Barbosa R, Kruse N. Higher alcohols through CO hydrogenation over CoCu catalysts: Influence of precursor activation. ACS Catal 2014, 4:2792-2800.

Taking Reference 2, which has a higher yield of low-carbon alcohols, as an example, the authors adopted a co-precipitation method to support CuCo catalysts on carbon nanotubes using layered double hydroxides as precursors. The CO conversion rate was 45.4% in the catalytic synthesis of low-carbon alcohol, the yield of low-carbon alcohol was 28.6%, and the catalyst stability was tested for 192 hours. Compared with reference 2, the present invention takes Example 2 as an example, no matter from the raw materials (few varieties, low price), preparation method (without tedious carrier pretreatment process and harsh preparation environment), CO in the synthesis of low-carbon alcohols. It has obvious advantages in conversion rate (82.4%), lower alcohol yield (48.6%) and catalyst life (>300h).

Comparative Example 1

The source and properties of the carrier mesoporous silica SBA-15 are the same as those in Example 2. The catalyst preparation steps of this comparative example are based on the preparation method steps in Example 2, and the following steps are further added: roasting in a muffle furnace at 400°C for 4 hours, and then reducing it in a hydrogen atmosphere at 450°C for 4 hours to obtain this comparative example. catalyst. The catalyst evaluation method is the same as that of Example 2, the catalyst evaluation results are shown in Table 3, and the XRD pattern thereof is shown in FIG. 3 .

Table 3 Reaction evaluation results of catalysts in different preparation processes

It can be seen from Table 3 and Figure 3 that the composition of the carrier is kept the same during the preparation process, and changing the decomposition and reduction process of the catalyst precursor has an important impact on the structure and activity of the final catalyst. In Example 2, calcination under nitrogen atmosphere will pyrolyze the solvent ligands into amorphous carbon, which plays the role of in-situ reduction and fills the pores of the carrier as a dispersant to prevent the migration and agglomeration of active nanoparticles. . As shown in the XRD pattern of Fig. 3, the confinement effect of carbon is lost by roasting in a muffle furnace, and the copper particles obtained under a hydrogen atmosphere are easy to agglomerate. From the aspect of catalytic performance, the catalyst obtained by direct inert atmosphere pyrolysis of the present invention has higher CO conversion rate and lower alcohol selectivity.

Comparative Example 2

The source and properties of the carrier mesoporous silica SBA-15 are the same as those in Example 2. The catalyst preparation steps of this comparative example refer to the preparation method in Example 2, and the only difference is that deionized water is used as the solvent, namely 1.0 g of copper nitrate (Cu(NO ₃ ) ₂ ·3H ₂ O), 2.6 g of cobalt nitrate (Co(NO ₃ ) ₂ ·6H ₂ O) was dissolved in 20 mL of deionized water, and the subsequent steps were the same as those in Example 2 to obtain the catalyst of this comparative example. The catalyst evaluation method is the same as that in Example 2, and the catalyst evaluation results are shown in Table 4.

Table 4 Reaction evaluation results of catalysts with different solvent precursors

It can be seen from Table 4 and Figure 4 that the choice of polyhydroxy solvent complexing agent has a great influence on the activity of the catalyst. The choice of deionized water as the solvent loses the coordination effect between the solvent and the metal ions, which is not conducive to the metal particles in the The confined growth inside the pores of the mesoporous material, and the obtained catalyst is mainly in the oxidation state, and the catalytic activity is low.

Comparative Example 3

The source and properties of the carrier mesoporous silica SBA-15 are the same as those in Example 2. The preparation steps of the catalyst of this comparative example are basically the same as those of the preparation method in Example 2, except that the last step is calcination at 400° C. for 5 h under N ₂ atmosphere to obtain the catalyst of this comparative example. The catalyst evaluation method is the same as that in Example 2, and the catalyst evaluation results are shown in Table 5.

It can be seen from Table 5 that the in-situ carbonization of the solvent ligands of the catalyst precursor at 550 °C can achieve higher CO conversion and higher selection of low-carbon alcohols than at 400 °C, and the distribution of alcohol products to low-carbon Alcohol orientation shift. Therefore, in the present invention, the catalyst obtained by carbonizing and decomposing the catalyst precursor at 550° C. is used in the low-carbon alcohol synthesis system.

The present invention has been exemplarily described above. It should be noted that, without departing from the core of the present invention, any simple deformation, modification, or other equivalent replacements that can be performed by those skilled in the art without any creative effort fall into the scope of the present invention. the scope of protection of the invention.

Claims

A solvent-coordinated metal catalyst is characterized in that, the catalyst uses a mesoporous material as a carrier, and is coordinated by a polyhydroxyl solvent and impregnated to reduce the active metal in situ, and the simultaneous confinement effect is confined in the pores of the mesoporous material. growing active nanoparticles;

Wherein, the mesoporous material is selected from SBA-15, KIT-6 or MCM-41; the active metals are Cu and M, and M is selected from Co, Fe, Ni, Mn, Mo, or Nb, preferably Co; the polyhydroxy solvent ligand is selected from ethylene glycol, 1,2-propanediol, 1,4-butanediol, or glycerol.
The solvent-coordinated metal catalyst according to claim 1, wherein the weight percentage of the catalyst is Cu: 1-30%, M: 1-30%, and the rest is a carrier, preferably, the catalyst is The weight percent composition is Cu: 7-13%, M: 7-13%, and the rest are carriers.
The solvent-coordinated metal catalyst according to claim 1, wherein the carrier has a specific surface area of 200-900 m 2 /g and an average pore diameter of 4-12 nm.
The method for preparing a solvent-coordinated metal catalyst according to any one of claims 1-3, characterized in that, using the mesoporous material as a carrier, a solvent-coordination impregnation method is used to confine the growth of Cu and M in the pores of the mesoporous material. The components are dried and pyrolyzed in an inert atmosphere to obtain a catalyst.
The method for preparing a solvent-coordinated metal catalyst according to claim 4, characterized in that, the Cu and M nanoparticles grown within the confinement in the pores are coordinated by metal ions corresponding to Cu and M to a polyhydroxyl solvent, so that The Cu and M are brought close to each other at the atomic level.
The method for preparing a solvent-coordinated metal catalyst according to claim 5, wherein the immersion time is 12-24 h; the ratio of the metal ions corresponding to the Cu and M is 3/1 to 1/3 (mol Compare).
The method for preparing a solvent-coordinated metal catalyst according to claim 5, wherein the metal ions corresponding to Cu and M are in the form of nitrates.
The method for preparing a solvent-coordinated metal catalyst according to claim 7, wherein the drying is vacuum drying at 100-150° C. for 10-36 hours.
The method for preparing a solvent-coordinated metal catalyst according to claim 7, wherein the inert atmosphere is pyrolyzed under an inert atmosphere at 350-650°C for 2-8 hours; preferably, the inert atmosphere is N 2 Atmosphere.
Application of any one of the solvent-coordinated metal catalysts of claims 1-3 in the preparation of low-carbon alcohols from coal-based or biomass-based synthesis gas.