Metal bulk phase catalyst for preparing methanol through carbon dioxide hydrogenation as well as preparation method and application of metal bulk phase catalyst

Abstract

The invention discloses a metal bulk phase catalyst for preparing methanol through carbon dioxide hydrogenation and a preparation method and application thereof.The metal bulk phase catalyst is composed of, by mass, 2-7% of indium metal element, 0.1-3% of zinc metal element, 0.1-3% of nickel metal element, 0.1-3% of cobalt metal element and the balance iron metal element, and the mass ratio of the indium metal element to the zinc metal element to the nickel metal element to the cobalt metal element to the iron metal element in the metal bulk phase catalyst is 1: 1. The catalyst comprises the following components in percentage by mass: 2-10% of a nickel metal element, 2-10% of a cobalt metal element and 70-93.9% of an iron metal element, and the sum of the mass ratios of the five metal elements is 100%. Experiments show that when the metal bulk phase catalyst is used for a reaction for preparing methanol through carbon dioxide hydrogenation, the metal bulk phase catalyst not only has excellent catalytic performance and stability, but also has a wide reaction temperature window, and is especially suitable for H2-rich feed gas; in addition, the metal bulk phase catalyst also has the advantages of simple preparation method, cheap and easily available raw materials, easy realization of large-scale production, easy molding and the like.

Description

Technical Field

[0001] The invention relates to a metal bulk catalyst for preparing methanol by hydrogenating carbon dioxide and a preparation method and application thereof, belonging to the technical field of catalysts. Background Art

[0002] Carbon dioxide, as a "carbon resource" that exists in large quantities in the atmosphere, plays a vital role in the global carbon cycle. However, in the past century, the extensive use of traditional fossil energy by humans has caused the emission of carbon dioxide in the atmosphere to far exceed the level that can be effectively fixed by plant photosynthesis and rainwater dissolution in nature, resulting in a continuous increase in the concentration of carbon dioxide in the global atmosphere, which has seriously damaged the carbon cycle balance of the global ecosystem, and has further caused a series of environmental problems such as climate anomalies, glacier melting and sea level rise, which seriously threatens the sustainable development of mankind.

[0003] In recent years, a series of initiatives have been proposed to address the problem of excessive carbon dioxide emissions. Among them, carbon dioxide capture and storage technology has received widespread attention due to the huge carbon dioxide storage potential in natural storage areas such as depleted oil and gas fields and abandoned coal seams. However, the uncertainty of carbon dioxide storage time and high operating costs have hindered its widespread application. It is worth noting that carbon dioxide is an abundant and cheap carbon-containing resource. In addition to directly capturing / storing carbon dioxide, how to effectively catalytically convert and utilize carbon dioxide to achieve an "artificial carbon cycle" has also become a hot topic for many scientific researchers.

[0004] With the increasing maturity of photolysis and electrolysis of water to produce hydrogen, the efficient conversion of carbon dioxide hydrogenation into methanol, methane, formic acid, low-carbon olefins, aromatics and other chemicals has become a promising way to utilize carbon dioxide. Among many chemicals, methanol is recognized as an important platform molecule. First, methanol can be derived into a series of downstream chemical products. For example, methanol can be directly used to manufacture formaldehyde, methylamine, methyl chloride, acetic acid, methyl tert-butyl ether, methyl methacrylate, dimethyl sulfate and other organic products; at the same time, thanks to the design and continuous optimization of molecular sieve catalysts, methanol can also partially replace traditional petrochemical products to produce ethylene, propylene and other basic chemical raw materials. Secondly, methanol itself also has important uses. On the one hand, because of its excellent solubility, it can be directly used as a solvent for chemicals such as paints, coatings, dyes, adhesives, cellulose, alkaloids, etc.; on the other hand, methanol is also a promising green vehicle and marine fuel. Therefore, direct production of methanol from carbon dioxide hydrogenation can not only solve energy problems, but also alleviate the greenhouse effect, and has important social significance and economic value.

[0005] The chemical equation and thermodynamic data of the carbon dioxide hydrogenation reaction are as follows:

[0006] CO2 +3H 2 →CH 3 OH+H 2 O(ΔH 0 298K) = -49.01 kJ / mol;

[0007] CO 2 +H 2 →CO+H 2 O(ΔH 0 298K) = +41.17 kJ / mol;

[0008] CO 2 +4H 2 →CH 4 +2H 2 O(ΔH 0 298K) = -165.00 kJ / mol;

[0009] From the above reaction equation, it can be seen that the hydrogenation of carbon dioxide to methanol is an exothermic reaction limited by thermodynamic equilibrium. High temperature is not conducive to the main reaction of methanol production, but it is favorable for the side reaction of carbon monoxide production. Generally speaking, when the temperature is higher than 300℃, the reverse water gas shift reaction (CO 2 +H 2 →CO+H 2 O) will significantly increase. At the same time, the catalyst may produce a certain amount of carbon deposits at this temperature, resulting in the Sabatier reaction (CO 2 +4H 2 →CH 4 +2H 2 O) will also significantly increase the methane produced, and the occurrence of these two side reactions seriously hinders the further improvement of methanol yield. Therefore, the development of economical and applicable catalysts with high activity and high methanol selectivity in a wide temperature window is the key to achieving large-scale industrialization of carbon dioxide hydrogenation to methanol, but it faces huge challenges.

[0010] At present, the catalysts for the hydrogenation of carbon dioxide to methanol are mainly divided into copper-based catalysts, precious metal-supported catalysts and metal oxide catalysts. In 1923, BASF (Badische Anilin and Soda Fabrik) of Germany used synthesis gas containing carbon dioxide as raw material and used zinc chromate (ZnO-Cr 2 O 3) as a catalyst, and commercial methanol synthesis was first achieved under reaction conditions of reaction temperature of 320-450°C and pressure of 250-300 bar. In the next 40 years, the reaction raw materials changed from coal to naphtha or natural gas, which continuously improved the purity of synthesis gas. Against this background, Imperial Chemical Industries (ICI) of the United Kingdom developed copper-zinc-aluminum (Cu-ZnO-Al 2 O 3 ) catalyst, and thereafter copper-based catalysts, such as Cu / ZrO 2 , Cu / CeO x / TiO 2 CuZnM (M = Al, Si, Ga, Fe, Zr) is widely used in the research of carbon dioxide hydrogenation to methanol. Among them, CuZnAlGa catalyst has good performance at 200℃ and H 2 / CO 2 =2,3500mL h -1 g -1 and 110 bar, despite a 30% higher CO 2 The conversion rate is 2.3%, but the methanol selectivity is only 69.3%. Therefore, due to the existence of the reverse water-gas shift competition reaction, the copper-based catalyst has the problem of low methanol selectivity. What is more serious is that the traditional Cu / ZnO catalyst (Appl. Catal. A, 2001, 218, 235) is directly used for the carbon dioxide hydrogenation reaction. The production of product water causes the Cu active component to sinter continuously, resulting in rapid deactivation of the catalyst. Patent (CN102302934A) discloses a novel catalyst for the catalytic hydrogenation of carbon dioxide to produce methanol modified by a novel additive, which is modified by adding a promoter SiO 2 -TiO 2 The stability of the Cu / ZnO catalyst was greatly improved, and the deactivation problem of the catalyst was solved to a certain extent. However, the methanol selectivity was only 41.17%. The patent (CN103272607) discloses a Cu / Zn / Al / Zr-based catalyst prepared by co-precipitation method using a polymer as a stabilizer. 2 The conversion rate is still far from the thermodynamic equilibrium conversion rate under the reaction conditions, especially the low methanol selectivity. Among the supported precious metal catalysts, Pd-based catalysts have better reaction performance, such as PdZn / CeO 2 Catalyst (Appl. Catal. A, 2019, 584, 117185), at 220 °C, 20 bar, H 2 / CO 2 =3, 2400h -1 Under the reaction conditions, CO2 The conversion rate can reach 14%, and the methanol selectivity can reach 95%; Pd-In / SiO 2 Catalyst (Appl. Catal. B, 2018, 220, 9), at 210 °C, 50 bar, H 2 / CO 2 =3 reaction conditions, the methanol generation rate is higher than that of Cu-ZnO-Al 2 O 3 The catalyst is about 70% (900 μmolmmol PdIn -1 h -1 and 540 μmol mmol CuZnAl -1 h -1 The patent (CN105498756A) discloses a supported Pd noble metal catalyst prepared by an impregnation method at 210°C, 40 bar, H 2 / CO 2 =3, 15000mL g -1 h -1 Under the reaction conditions, 15.7% CO was obtained. 2 The patent (CN101444731A) discloses a PdZn catalyst with carbon nanotube-based materials as promoter, which can be used at 270℃, 50bar, H 2 / CO 2 =3, 15000mL g -1 h -1 Under the reaction conditions, nearly 7% CO 2 The conversion rate and methanol selectivity are close to 100%. Although Pd-based catalysts have good reaction performance, the rare content and high price of precious metals, mainly Pd, limit their large-scale preparation and application. 2 O 3 Because of its high methanol selectivity, it has attracted much attention. The literature (Angew. Chem. Int. Ed., 2016, 55, 6261) reported a ZrO 2 Load In 2 O 3 Catalyst, at 300°C, 50 bar, H 2 / CO 2 =4, 16000h -1 Under the reaction conditions, 100% methanol selectivity was obtained, but its CO 2 The conversion rate and methanol space-time yield still need to be further improved (CO 2 The conversion rate is only 5%, and the methanol space-time yield is only 0.295g MeOHg cat -1 h -1 ).

[0011] Since the hydrogenation of carbon dioxide to methanol is an exothermic process, low-temperature reactions are thermodynamically favorable. In addition, although noble metals (such as Pd) have good low-temperature activity and selectivity, they are expensive; while non-noble metal catalysts have good catalytic selectivity, but poor low-temperature activity. Therefore, the art is in urgent need of developing a catalyst for the hydrogenation of carbon dioxide to methanol that has high activity at low temperatures, high methanol selectivity, high methanol space-time yield, good stability, wide operating temperature window, low preparation cost, and is easy to scale up. Summary of the invention

[0012] In view of the above problems and needs in the prior art, the object of the present invention is to provide a metal bulk catalyst for producing methanol by hydrogenation of carbon dioxide and a preparation method and application thereof.

[0013] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0014] A metal bulk catalyst for hydrogenating carbon dioxide to produce methanol is composed of five metal elements, namely, indium (In), zinc (Zn), nickel (Ni), cobalt (Co), and iron (Fe). The mass proportion of each metal element in the metal bulk catalyst is as follows:

[0015] Indium metal element 2-7%;

[0016] Zinc metal element 0.1-3%;

[0017] Nickel metal element 2-10%;

[0018] Cobalt metal element 2-10%;

[0019] Iron metal elements 70-93.9%;

[0020] The sum of the mass percentages of the above five metal elements is 100%.

[0021] Furthermore, the metal bulk catalyst contains at least Fe, FeNi, FeCo and In 3 Ni 2 Nanocrystalline particles.

[0022] Furthermore, the metal bulk catalyst contains at least Fe, FeNi, FeCo, In 3 Ni 2 、FeZn 7 and Ni 5 Zn 21 Nanocrystals.

[0023] In one embodiment, the method for preparing the metal bulk catalyst of the present invention comprises the following steps:

[0024] S1) Weighing calculated amounts of oxides and / or hydroxides of metals In, Zn, Ni, Co, and Fe respectively, and mixing them uniformly;

[0025] S2) calcining the mixture obtained in step S1) at 300-600° C. in an air atmosphere for 0.5-12 hours;

[0026] S3) with H 2 The product calcined in step S2) is subjected to reduction treatment with a reducing gas or a mixed gas at 500-600° C. under normal pressure for 1-3 hours, and the obtained powder is the metal bulk catalyst.

[0027] In step S1), the oxide of Co metal includes CoO, Co 3 O 4 、Co 2 O 3 At least one of .

[0028] In step S1), the Fe metal oxide includes FeO, Fe 3 O 4 , Fe 2 O 3 At least one of .

[0029] In step S1), the hydroxide of Fe metal comprises Fe(OH) 2 、Fe(OH) 3 At least one of .

[0030] In another embodiment, the method for preparing the metal bulk catalyst of the present invention comprises the following steps:

[0031] a) Weighing calculated amounts of water-soluble metal salts of In, Zn, Ni and Co respectively, and dissolving them completely in water to form a mixed aqueous solution;

[0032] b) adding Fe powder and / or Fe oxide and / or Fe hydroxide to the mixed aqueous solution obtained in step a), then heating at 70-100° C. for 3-5 hours, evaporating water, and then calcining in air at 300-500° C. for 0.5-12 hours;

[0033] c) Use H 2 The product after calcination in step b) is subjected to reduction treatment by a reducing gas or a mixed gas at 500-600° C. under normal pressure for 1-3 hours, and the obtained powder is the metal bulk catalyst.

[0034] In step a), the water-soluble metal salt is selected from one or more of the nitrates, hydrochlorides, sulfates and acetates of various metals.

[0035] In another embodiment, the method for preparing the metal bulk catalyst of the present invention comprises the following steps:

[0036] ① Weigh the calculated amounts of In, Zn, Ni, Co, and Fe metal powders respectively and mix them evenly;

[0037] ②Use H 2 The mixture obtained in step ① is subjected to reduction treatment with a reducing gas or a mixed gas at 600-800° C. under normal pressure for 3-5 hours, and the obtained powder is the metal phase catalyst.

[0038] According to a further embodiment, the above preparation method further comprises the following forming step:

[0039] A) purging and passivating the obtained metal bulk catalyst powder with an oxygen-nitrogen mixed gas at room temperature;

[0040] B) mixing the metal bulk catalyst powder after the passivation treatment in step A) with the required amount of graphite powder and SiO 2 and / or Al 2 O 3 After uniform mixing, the catalyst is formed by tableting with a tabletting machine.

[0041] As a preferred solution, the volume fraction of oxygen in the oxygen-nitrogen mixed gas is 0.5%.

[0042] As a preferred embodiment, in the shaped catalyst, the mass proportion of the metal bulk catalyst is not less than 85%.

[0043] As a preferred embodiment, the radial crushing strength of the molded catalyst is not less than 100 N / cm.

[0044] The metal bulk catalyst and the shaped catalyst described in the present invention can both be used as catalysts for the reaction of hydrogenating carbon dioxide to produce methanol.

[0045] As a preferred embodiment, the reaction conditions are: in a fixed bed at 180-320°C and 4-8 MPa pressure, H 2 With CO 2 The volume ratio is 3:1 to 10:1, and the gas hourly space velocity is 12000 to 36000 mL / g cat / h.

[0046] Compared with the prior art, the present invention has the following significant beneficial effects:

[0047] Experiments show that the metal bulk catalyst provided by the present invention, when used for the reaction of hydrogenating carbon dioxide to produce methanol, not only has high selectivity for the target product methanol (higher than 90%, up to 99.4%), low selectivity for the by-product methane (less than 0.1%), but also has high single-pass conversion rate of carbon dioxide (higher than 6%, up to 32.1%), wide reaction temperature window (even at a low temperature of 180°C, the single-pass conversion rate of carbon dioxide can still reach 6%, while the selectivity of methanol can reach 99.4%, and no methane is generated; and at a high temperature of 320°C, the single-pass conversion rate of carbon dioxide can also reach 22%, while the selectivity of methanol is maintained at more than 90%, and the selectivity of methane is only 0.1%), and is particularly suitable for H-rich products. 2 Raw gas (can be at 250℃, 4.0MPa, 12000mL / g cat / h, with H 2 / CO 2 = 10 / 1 (volume / volume) mixed gas as raw material, the single-pass conversion rate of carbon dioxide reached 32.1%, the selectivity of methanol reached 98.6%, the rest was CO, and the selectivity of methane was 0), and it had good stability (in the 200-hour test process, CO 2 The conversion rate and methanol selectivity are both maintained stable, with no signs of deactivation); in addition, the metal bulk catalyst described in the present invention also has the advantages of simple preparation method, cheap and readily available raw materials, easy large-scale production and easy molding, and has significant industrial application value, which is of great significance for the industrialization of carbon dioxide to methanol. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a transmission electron microscope image of the metallic bulk catalyst IZNFC-1 prepared in Example 1;

[0049] Figure 2 This is a physical photo of the metallic bulk catalyst IZNFC-2 prepared in Example 2;

[0050] Figure 3 is a transmission electron microscope image of the metallic bulk catalyst IZNFC-2 prepared in Example 2;

[0051] Figure 4 is a transmission electron microscope image of the metallic bulk catalyst IZNFC-3 prepared in Example 3;

[0052] Figure 5 This is a physical photo of the formed catalyst IZNCF-CX prepared in Example 4;

[0053] Figure 6 is a transmission electron microscope image of a comparative metal bulk catalyst prepared in Comparative Example 6;

[0054] Figure 7 This is the stability test result of the catalyst IZNCF-2 in Application Example 1 in the reaction of hydrogenating carbon dioxide to produce methanol. DETAILED DESCRIPTION

[0055] The technical solution of the present invention is further described in detail and completely below in combination with embodiments, comparative examples and application examples.

[0056] Example 1

[0057] S1) Weigh 0.60 g of In 2 O 3 , 0.025 g ZnO, 0.33 g NiO, 0.68 g Co 3 O 4 and 12.67 g of Fe 2 O 3 , grind in a mortar to mix well;

[0058] S2) calcining the mixture obtained in step S1) at 500° C. for 5 hours in an air atmosphere;

[0059] S3) with H 2 The product calcined in step S2) is reduced by a reducing gas at 525° C. under normal pressure for 3 hours to obtain a powder, which is the metallic bulk catalyst and is denoted as IZNCF-1.

[0060] Plasma inductively coupled atomic emission spectroscopy (ICP) measurement revealed that in the metal bulk catalyst prepared in this embodiment, the mass content of the In element was 4.9%, the mass content of the Zn element was 0.2%, the mass content of the Ni element was 2.6%, the mass content of the Co element was 4.9%, and the mass content of the Fe element was 87.4%.

[0061] Figure 1 is a transmission electron microscope image of the metallic bulk catalyst IZNFC-1 prepared in this example. Figure 1 As shown in the figure, the metal bulk catalyst prepared in this embodiment contains Fe, FeNi, FeCo and In 3 Ni 2 Nanocrystalline, no FeZn found 7 and Ni 5 Zn 21 Nano-grains, which may be due to the low content of Zn.

[0062] In addition, this embodiment can also be evolved as follows:

[0063] In step S1), the metal precursors of In, Zn, Ni, Co and Fe are selected from the hydroxides or mixtures of oxides and hydroxides of the metals, and the oxide of Co metal is selected from CoO, Co 3 O 4 、Co 2 O 3 At least one of the following, the Fe metal oxide is selected from FeO, Fe 3 O 4 , Fe 2 O 3 At least one of the following, the hydroxide of Fe metal is selected from Fe(OH) 2 、Fe(OH) 3 At least one of the above conditions is met, while the other conditions remain unchanged;

[0064] In step S1), the amount of each metal precursor of In, Zn, Ni, Co, and Fe can be selected according to the mass proportion of each metal element in the metal bulk catalyst: "2-7% indium metal element, 0.1-3% zinc metal element, 2-10% nickel metal element, 2-10% cobalt metal element, and the balance is iron metal element", while the other conditions remain unchanged;

[0065] In step S2), the calcination temperature can be selected within the range of 300 to 600°C, and the calcination time can be selected within the range of 0.5 to 12 hours, while the other conditions remain unchanged;

[0066] In step S3), the reduction treatment temperature can be selected within the range of 500 to 600° C., and the reduction treatment time can be selected within the range of 1 to 3 hours, while the other conditions remain unchanged;

[0067] In step S3), H 2 The reducing gas can also be H 2 The mixture of gases is replaced by the mixture of gases, while other conditions remain unchanged.

[0068] Example 2

[0069] a) 0.97 g of indium nitrate tetrahydrate, 0.9 g of zinc nitrate hexahydrate, 1.52 g of nickel nitrate hexahydrate and 3.04 g of cobalt nitrate hexahydrate were weighed respectively and completely dissolved in 50 ml of distilled water to prepare a mixed aqueous solution;

[0070] b) weighing 8.55 g of iron powder with a particle size of 100 to 200 μm, adding it to the mixed aqueous solution prepared in step a), and heating it at 85° C. for 4 hours; heating and evaporating the water in the system, and then calcining it in air at 450° C. for 8 hours;

[0071] c) Use H 2The product calcined in step b) is subjected to reduction treatment with reducing gas at 500° C. under normal pressure for 3 hours to obtain a powder, which is the metallic bulk catalyst, denoted as IZNCF-2.

[0072] Plasma inductively coupled atomic emission spectroscopy (ICP) measurement revealed that in the metal bulk catalyst prepared in this embodiment, the mass content of the In element was 3.1%, the mass content of the Zn element was 1.9%, the mass content of the Ni element was 3.2%, the mass content of the Co element was 6.0%, and the mass content of the Fe element was 85.8%.

[0073] Figure 2 is a physical photo of the metal bulk catalyst IZNFC-2 prepared in this example. Figure 2 As shown, the obtained catalyst is black and has uniform color, indicating that the catalyst is completely reduced and has uniform composition distribution.

[0074] Figure 3 is a transmission electron microscope image of the metallic bulk catalyst IZNFC-2 prepared in this example. Figure 3 As shown in the figure, the metal bulk catalyst prepared in this embodiment contains Fe, FeNi, FeCo, In 3 Ni 2 、FeZn 7 and Ni 5 Zn 21 Nanocrystalline particles.

[0075] In addition, this embodiment can also be evolved as follows:

[0076] In step a), the metal salt precursors of In, Zn, Ni, and Co can be selected from one or more water-soluble metal salts of nitrates, hydrochlorides, sulfates, and acetates; the amounts of the metal salt precursors of In, Zn, Ni, and Co can be selected according to the mass proportion of each metal element in the metal phase catalyst: "indium metal element 2-7%, zinc metal element 0.1-3%, nickel metal element 2-10%, cobalt metal element 2-10%", while the other conditions remain unchanged;

[0077] In step b), the metal Fe powder can be replaced by a mixture of Fe powder and Fe oxide, a mixture of Fe powder and Fe hydroxide, a mixture of Fe oxide and Fe hydroxide, Fe oxide, or Fe hydroxide, while the other conditions remain unchanged; the amount of the iron element precursor can also be selected according to the mass ratio range of the iron metal element in the metal phase catalyst: "70-93.9%", while the other conditions remain unchanged;

[0078] In step b), the heating treatment temperature can also be selected within the range of 70 to 100° C., the heating treatment time can also be selected within 3 to 5 hours, and the other conditions remain unchanged; the roasting temperature can also be selected within the range of 300 to 500° C., the roasting time can also be selected within the range of 0.5 to 12 hours, and the other conditions remain unchanged;

[0079] In step c), the reduction treatment temperature can be selected within the range of 500 to 600° C., and the reduction treatment time can be selected within the range of 1 to 3 hours, while the other conditions remain unchanged;

[0080] In step c), H 2 The reducing gas can also be H 2 The mixture of gases is replaced by the mixture of gases, while other conditions remain unchanged.

[0081] Example 3

[0082] ① Weigh 0.7 g of In metal powder, 0.1 g of Zn metal powder, 0.8 g of Ni metal powder, 0.9 g of Co metal powder and 7.5 g of Fe metal powder respectively and mix them evenly;

[0083] ②Use H 2 The mixture obtained in step ① is reduced by a reducing gas at 600° C. under normal pressure for 5 hours, and the obtained powder is the metal phase catalyst, which is denoted as IZNCF-3.

[0084] Plasma inductively coupled atomic emission spectroscopy (ICP) measurement revealed that in the metal bulk catalyst prepared in this embodiment, the mass content of the In element was 7%, the mass content of the Zn element was 1%, the mass content of the Ni element was 8%, the mass content of the Co element was 9%, and the mass content of the Fe element was 75%.

[0085] Figure 4 is a transmission electron microscope image of the metallic bulk catalyst IZNFC-3 prepared in this example. Figure 4 As shown in the figure, the metal bulk catalyst prepared in this embodiment contains Fe, FeNi, FeCo, In 3 Ni 2 、FeZn 7 and Ni 5 Zn 21 Nanocrystalline particles.

[0086] In addition, this embodiment can also be evolved as follows:

[0087] In step ①, the amount of each metal powder of In, Zn, Ni, Co, and Fe can be selected according to the mass proportion of each metal element in the metal bulk catalyst: "2-7% indium metal element, 0.1-3% zinc metal element, 2-10% nickel metal element, 2-10% cobalt metal element, and the balance is iron metal element", while the other conditions remain unchanged;

[0088] In step ②, the reduction treatment temperature can be selected within 600 to 800° C., and the reduction treatment time can be selected within 3 to 5 hours, while the other conditions remain unchanged;

[0089] In step ②, H 2 The reducing gas can also be H 2 The mixture of gases is replaced by the mixture of gases, while other conditions remain unchanged.

[0090] Example 4

[0091] A) preparing a metallic bulk catalyst according to Example 2, and the obtained catalyst powder was purged and passivated with an oxygen-nitrogen mixed gas (wherein the oxygen volume fraction was 0.5%) at room temperature;

[0092] B) Weigh 90 g of the metal bulk catalyst powder after the passivation treatment in step A), 3 g of graphite powder and 7 g of Al 2 O 3 After uniform mixing, the catalyst was tableted by a tabletting machine to obtain a shaped catalyst, which was recorded as IZNCF-CX.

[0093] It was determined that the radial crushing strength of the obtained molded catalyst IZNCF-CX was 120 N / cm.

[0094] In addition, this embodiment can also be evolved as follows:

[0095] In step A), the metal bulk catalyst powder may be a mixture of any one or more of Examples 1 to 3, or a mixture of any one or more of the modified examples of Examples 1 to 3, while the other conditions remain unchanged;

[0096] In step B), Al 2 O 3 SiO 2 or Al 2 O 3 With SiO 2 The mixture is replaced by , while the other conditions remain unchanged;

[0097] In step B), the mass proportion of the metal bulk catalyst can be selected within a range of not less than 85%, and the remainder is graphite powder and SiO 2 and / or Al 2 O 3, while the other conditions remain unchanged.

[0098] Figure 5 is a photo of the shaped catalyst IZNCF-CX prepared in this example. Figure 5 It can be seen that the catalyst formed into tablets is in a regular cylindrical shape, with uniform particle size and color.

[0099] Comparative Example 1

[0100] This comparative example adopts the preparation method described in Example 3:

[0101] ① Weigh 0.7 g of In metal powder, 0.2 g of Zn metal powder and 9.1 g of Fe metal powder respectively and mix them evenly;

[0102] ②Use H 2 The mixture obtained in step ① is reduced by reducing gas at 600° C. under normal pressure for 5 hours, and the obtained powder is a comparative metal bulk catalyst, denoted as: IZF.

[0103] The results of plasma inductively coupled atomic emission spectroscopy (ICP) showed that the mass content of In element in the metal phase catalyst prepared in this comparative example was 7%, the mass content of Zn element was 2%, the mass content of Ni element was 0%, the mass content of Co element was 0%, and the mass content of Fe element was 91%.

[0104] Comparative Example 2

[0105] This comparative example adopts the preparation method described in Example 3:

[0106] ① Weigh 0.7 g of In metal powder, 0.2 g of Zn metal powder, 0.8 g of Ni metal powder and 8.3 g of Fe metal powder respectively and mix them evenly;

[0107] ②Use H 2 The mixture obtained in step ① is reduced by reducing gas at 600° C. under normal pressure for 5 hours, and the obtained powder is a comparative metal bulk catalyst, denoted as: IZNF.

[0108] The results of plasma inductively coupled atomic emission spectroscopy (ICP) showed that the mass content of In element in the metal phase catalyst prepared in this comparative example was 7%, the mass content of Zn element was 2%, the mass content of Ni element was 8%, the mass content of Co element was 0%, and the mass content of Fe element was 83%.

[0109] Comparative Example 3

[0110] This comparative example adopts the preparation method described in Example 3:

[0111] ① Weigh 0.7 g of In metal powder, 0.2 g of Zn metal powder, 1.0 g of Co metal powder and 8.1 g of Fe metal powder respectively and mix them evenly;

[0112] ②Use H 2 The mixture obtained in step ① is reduced by reducing gas at 600° C. under normal pressure for 5 hours, and the obtained powder is a comparative metal bulk catalyst, denoted as: IZCF.

[0113] The results of inductively coupled plasma atomic emission spectroscopy (ICP) showed that the mass content of the In element in the metal phase catalyst prepared in this comparative example was 7%, the mass content of the Zn element was 2%, the mass content of the Ni element was 0%, the mass content of the Co element was 10%, and the mass content of the Fe element was 81%.

[0114] Comparative Example 4

[0115] This comparative example adopts the preparation method described in Example 3:

[0116] ① Weigh 0.7 g of In metal powder, 0.8 g of Ni metal powder, 1.0 g of Co metal powder and 7.5 g of Fe metal powder respectively and mix them evenly;

[0117] ②Use H 2 The mixture obtained in step ① is reduced by reducing gas at 600° C. under normal pressure for 5 hours to obtain a powder, which is a comparative metal bulk catalyst and is denoted as INCF.

[0118] The results of plasma inductively coupled atomic emission spectroscopy (ICP) showed that the mass content of In element in the metal phase catalyst prepared in this comparative example was 7%, the mass content of Zn element was 0%, the mass content of Ni element was 8%, the mass content of Co element was 10%, and the mass content of Fe element was 75%.

[0119] Comparative Example 5

[0120] This comparative example adopts the preparation method described in Example 3:

[0121] ① Weigh 0.2 g of Zn metal powder, 0.8 g of Ni metal powder, 1.0 g of Co metal powder and 8.0 g of Fe metal powder respectively and mix them evenly;

[0122] ②Use H 2 The mixture obtained in step ① is reduced by reducing gas at 600° C. under normal pressure for 5 hours, and the obtained powder is a comparative metal bulk catalyst, denoted as: ZNCF.

[0123] The results of plasma inductively coupled atomic emission spectroscopy (ICP) showed that the mass content of In element in the metal phase catalyst prepared in this comparative example was 0%, the mass content of Zn element was 2%, the mass content of Ni element was 8%, the mass content of Co element was 10%, and the mass content of Fe element was 80%.

[0124] Comparative Example 6

[0125] This comparative example adopts the preparation method described in Example 3:

[0126] ① Weigh 0.05 g of In metal powder, 0.05 g of Zn metal powder, 0.1 g of Ni metal powder, 0.1 g of Co metal powder and 9.7 g of Fe metal powder respectively and mix them evenly;

[0127] ②Use H 2 The mixture obtained in step ① is reduced by reducing gas at 600° C. under normal pressure for 5 hours to obtain a powder, which is a comparative metal bulk catalyst and is denoted as IZNCF-DB.

[0128] The results of plasma inductively coupled atomic emission spectroscopy (ICP) showed that the mass content of the In element in the metal phase catalyst prepared in this comparative example was 0.5%, the mass content of the Zn element was 0.5%, the mass content of the Ni element was 1%, the mass content of the Co element was 1%, and the mass content of the Fe element was 97%.

[0129] Figure 6 is a transmission electron microscope image of the comparative metal bulk catalyst prepared in this comparative example, Figure 6 As shown in the figure, the catalyst of this comparative example only contains Fe, FeNi and FeCo nanoparticles, and no In 3 Ni 2 、FeZn 7 and Ni 5 Zn 21 Nano-grains, which may be due to the low contents of In and Zn.

[0130] Application Example 1

[0131] In a fixed bed reactor, the metal bulk catalyst prepared in Example 2 was used to investigate the catalytic performance of carbon dioxide hydrogenation to methanol under different reaction conditions:

[0132] A stainless steel fixed bed reactor with an aluminum liner is used, and the catalyst is filled in the aluminum liner, wherein the liner has an outer diameter of 10 mm, an inner diameter of 8 mm, and a length of 770 mm; the reaction products are quantitatively detected and analyzed online by a gas chromatograph equipped with a hydrogen flame ionization detector (FID) and a thermal conductivity detector (TCD); the performance of the metal bulk catalyst is directly tested under the set reaction conditions without further activation treatment.

[0133] Reaction conditions 1: reaction temperature is 180-320°C, reaction pressure is 4.0 MPa, H 2 / CO 2 =5 / 1 (volume ratio), catalyst dosage is 0.50 g, gas hourly space velocity is 12000 mL / g cat / h(ie:CO 2 Gas hourly space velocity is 2000mL / g cat / h);

[0134] Under the above conditions, the effect of reaction temperature on catalytic performance was investigated, and the reaction results are shown in Table 1.

[0135] Table 1 Catalytic performance of carbon dioxide hydrogenation to methanol at different reaction temperatures

[0136]

[0137] From the results shown in Table 1, it can be seen that, under the premise that other conditions are the same, increasing the temperature is beneficial to improving the single-pass conversion rate of carbon dioxide, but it will reduce the selectivity of methanol and gradually increase the by-products of CO and methane.

[0138] Reaction conditions 2: reaction temperature is 250°C, reaction pressure is 4.0MPa, catalyst dosage is 0.50g, CO 2 Gas hourly space velocity is 2000mL / g cat / h;

[0139] Under the above conditions, the H 2 / CO 2 The effect of the volume ratio on the catalytic performance and the reaction results are shown in Table 2.

[0140] Table 2 Different H 2 / CO 2 Effect of volume ratio of carbon dioxide on catalytic performance of methanol hydrogenation

[0141]

[0142] From the results shown in Table 2, it can be seen that under the premise that other conditions are the same, H 2 / CO 2The larger the volume ratio of the catalyst, the more favorable it is for improving the single-pass conversion rate of carbon dioxide and the selectivity of methanol, and reducing the by-products of CO and methane at the same time, which indicates that the metal bulk catalyst of the present invention is suitable for H-rich 2 The catalytic performance of hydrogenating carbon dioxide in the feed gas to produce methanol is very excellent.

[0143] Reaction condition 3: reaction temperature is 250℃, H 2 / CO 2 =5 / 1 (volume ratio), catalyst dosage is 0.50 g, gas hourly space velocity is 12000 mL / g cat / h(ie:CO 2 Gas hourly space velocity is 2000mL / g cat / h);

[0144] Under the above conditions, the effect of reaction pressure on catalytic performance was investigated, and the reaction results are shown in Table 3.

[0145] Table 3 Catalytic performance of carbon dioxide hydrogenation to methanol at different reaction pressures

[0146]

[0147] From the results shown in Table 3, it can be seen that, under the premise that other conditions are the same, the increase in reaction pressure will be beneficial to improving the single-pass conversion rate of carbon dioxide and the selectivity of methanol, and can simultaneously reduce CO and methane by-products.

[0148] Reaction conditions 4: reaction temperature is 250°C, reaction pressure is 4.0 MPa, H 2 / CO 2 =5 / 1 (volume ratio), the amount of catalyst is 0.50 g;

[0149] Under the above conditions, the effect of gas hourly space velocity on the catalytic performance was investigated, and the reaction results are shown in Table 4.

[0150] Table 4 Catalytic performance of carbon dioxide hydrogenation to methanol at different gas hourly space velocities

[0151]

[0152] From the results shown in Table 4, it can be seen that, under the premise that other conditions are the same, an increase in the gas hourly space velocity will be beneficial to improving the single-pass conversion rate of carbon dioxide and the selectivity of methanol, and can simultaneously reduce CO and methane by-products.

[0153] In addition, when the reaction temperature is 200-300°C, the reaction pressure is 4 MPa, and the H 2 / CO 2=5:1 (volume ratio) and a catalyst dosage of 0.50 g, the stability of the catalytic performance in the carbon dioxide hydrogenation to methanol reaction was investigated using the metal bulk catalyst prepared in Example 2.

[0154] Figure 7 is the stability test result, Figure 7 As shown in the figure, the metal bulk catalyst prepared in Example 2 of the present invention has good stability. During the 200-hour test, the CO 2 Both conversion and methanol selectivity remained stable with no signs of deactivation.

[0155] Application Example 2

[0156] The catalytic performance of the catalysts of Examples 1 to 4 and Comparative Examples 1 to 6 for the hydrogenation of carbon dioxide to methanol reaction was investigated in a fixed bed reactor:

[0157] A stainless steel fixed bed reactor with an aluminum liner is used, and the catalyst is filled in the aluminum liner, wherein the liner has an outer diameter of 10 mm, an inner diameter of 8 mm, and a length of 770 mm; the reaction products are quantitatively detected and analyzed online by a gas chromatograph equipped with a hydrogen flame ionization detector (FID) and a thermal conductivity detector (TCD); the performance of each catalyst is directly tested under the set reaction conditions without further activation treatment.

[0158] Reaction conditions: reaction temperature is 250℃, reaction pressure is 8.0MPa, H 2 / CO 2 =5 / 1 (volume ratio), catalyst dosage is 0.50 g, gas hourly space velocity is 12000 mL / g cat / h(ie:CO 2 Gas hourly space velocity is 2000mL / g cat / h).

[0159] Under the above reaction conditions, the catalytic performance of each catalyst for hydrogenation of carbon dioxide to methanol is shown in Table 5.

[0160] Table 5 Catalytic performance of various catalysts for hydrogenation of carbon dioxide to methanol

[0161]

[0162] From the results shown in Table 5, it can be seen that the metal bulk catalyst described in the present invention (composed of 5 metal elements, namely In, Zn, Ni, Co and Fe, wherein the mass proportion of each metal element in the metal bulk catalyst is: 2-7% indium metal element, 0.1-3% zinc metal element, 2-10% nickel metal element, 2-10% cobalt metal element, and 70-93.9% iron metal element) is used as a catalyst for the reaction of hydrogenating carbon dioxide to produce methanol, and all of them have excellent catalytic activity and high selectivity for methanol, and the molded catalyst after molding has a catalytic performance equivalent to that of the powder (please compare Examples 2 and 4); however, if the constituent metal elements are not the 5 metal elements in the metal bulk catalyst described in the present invention, even if they are 3 or 4 metals therein, and the mass proportion of the metal elements contained in the obtained catalyst is also within the range described in the present invention, the excellent properties of the metal bulk catalyst described in the present invention cannot be obtained. The present invention has different catalytic performance (please compare Example 3 with Comparative Examples 1 to 5), and even if the constituent metal elements are 5 of the metal bulk catalysts described in the present invention, if the mass proportion of each metal element in the obtained catalyst is not within the range described in the present invention, the excellent catalytic performance of the metal bulk catalyst described in the present invention cannot be obtained (please compare Example 3 with Comparative Example 6); through the embodiments and comparative examples, it can be clearly seen that the excellent catalytic performance of the catalyst described in the present invention depends on the specific combination of the 5 metal elements, which is not obviously predictable and known; the present invention is not only significantly progressive, but also produces unexpected technical effects; in addition, the metal bulk catalyst described in the present invention also has the advantages of simple preparation method, cheap and easy to obtain raw materials, easy to realize large-scale production and easy to shape; therefore, the present invention has industrial application value and is of great significance to the industrialization of carbon dioxide to methanol.

[0163] Finally, it should be pointed out that the above are only some preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above contents of the present invention all fall within the scope of protection of the present invention.

Claims

1. A bulk metal catalyst for hydrogenation of carbon dioxide to methanol, Features: The metal bulk catalyst is composed of five metal elements, namely, indium (In), zinc (Zn), nickel (Ni), cobalt (Co), and iron (Fe), wherein the mass proportion of each metal element in the metal bulk catalyst is as follows: Indium metal element 2-7%; Zinc metal element 0.1-3%; Nickel metal element 2-10%; Cobalt metal element 2-10%; Iron metal elements 70-93.9%; The sum of the mass percentages of the above five metal elements is 100%.

2. The metal bulk catalyst according to claim 1, Features: The metal bulk catalyst contains at least Fe, FeNi, FeCo and In 3 Ni 2 Nanocrystalline particles.

3. A method for preparing the metal bulk catalyst according to claim 1, It is characterized in that The preparation method comprises the following steps: S1) Weighing calculated amounts of oxides and / or hydroxides of metals In, Zn, Ni, Co, and Fe respectively, and mixing them uniformly; S2) calcining the mixture obtained in step S1) at 300-600° C. in an air atmosphere for 0.5-12 hours; S3) with H 2 The product calcined in step S2) is subjected to reduction treatment with a reducing gas or a mixed gas at 500-600° C. under normal pressure for 1-3 hours, and the obtained powder is the metal bulk catalyst.

4. The preparation method according to claim 3, Features: In step S1), the oxide of Co metal includes CoO, Co 3 O 4 、Co 2 O 3 At least one of the Fe metal oxides includes FeO, Fe 3 O 4 , Fe 2 O 3 At least one of the following, the hydroxide of Fe metal comprises Fe(OH) 2 、Fe(OH) 3 At least one of .

5. A method for preparing the metal bulk catalyst according to claim 1, It is characterized in that The preparation method comprises the following steps: a) Weighing calculated amounts of water-soluble metal salts of In, Zn, Ni and Co respectively, and dissolving them completely in water to form a mixed aqueous solution; b) adding Fe powder and / or Fe oxide and / or Fe hydroxide to the mixed aqueous solution obtained in step a), then heating at 70-100° C. for 3-5 hours, evaporating water, and then calcining in air at 300-500° C. for 0.5-12 hours; c) Use H 2 The product after calcination in step b) is subjected to reduction treatment by a reducing gas or a mixed gas at 500-600° C. under normal pressure for 1-3 hours, and the obtained powder is the metal bulk catalyst.

6. The preparation method according to claim 5, Features: In step a), the water-soluble metal salt is selected from one or more of the nitrates, hydrochlorides, sulfates and acetates of various metals.

7. A method for preparing the metal bulk catalyst according to claim 1, It is characterized in that The preparation method comprises the following steps: ① Weigh the calculated amounts of In, Zn, Ni, Co, and Fe metal powders respectively and mix them evenly; ②Use H 2 The mixture obtained in step ① is subjected to reduction treatment with a reducing gas or a mixed gas at 600-800° C. under normal pressure for 3-5 hours, and the obtained powder is the metal phase catalyst.

8. The preparation method according to claim 3, 5 or 7, It is characterized in that The following molding steps are also included: A) purging and passivating the obtained metal bulk catalyst powder with an oxygen-nitrogen mixed gas at room temperature; B) mixing the metal bulk catalyst powder after the passivation treatment in step A) with the required amount of graphite powder and SiO 2 and / or Al 2 O 3 After uniform mixing, the catalyst is formed by tableting with a tabletting machine.

9. Use of the metal bulk catalyst according to claim 1 or 2, It is characterized in that Under the following conditions: In a fixed bed at 180-320°C and 4-8MPa pressure, H in the raw gas 2 With CO 2 The volume ratio is 3:1 to 10:1, and the gas hourly space velocity is 12000 to 36000 mL / g cat / h catalytic carbon dioxide hydrogenation to methanol reaction.

10. Use of the shaped catalyst according to claim 8, It is characterized in that Under the following conditions: In a fixed bed at 180-320°C and 4-8MPa pressure, H in the raw gas 2 With CO 2 The volume ratio is 3:1 to 10:1, and the gas hourly space velocity is 12000 to 36000 mL / g cat / h catalytic carbon dioxide hydrogenation to methanol reaction.

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