Multi-metal oxide catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of multi-metal oxide catalysts, in particular to a multi-metal oxide catalyst. The catalyst comprises an oxide of a main metal element and an oxide of an auxiliary metal element, wherein the main metal element is Fe; the molar ratio of the main metal element to the auxiliary metal element is 10: (1-8); the oxygen element concentration in the multi-metal oxide catalyst is 17-22 wt%; in the multi-metal oxide catalyst, the oxygen element concentration in a region from the surface to a depth of 10 nm below the surface is 52-66 wt%; the multi-metal oxide catalyst has a non-mixture phase. The catalyst has a non-mixture phase, surface metal elements are uniformly distributed, and the catalyst has high catalytic activity in a carbon-resource conversion reaction, so that products can be distributed on light components (C5 and below) in a concentrated manner, and particularly, the yield of C1-C3 products can be remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-metal oxide catalysts, and in particular to a multi-metal oxide catalyst and a preparation method and application thereof. Background Art

[0002] Metal oxides are commonly used catalysts or carriers in heterogeneous catalysis. They have the advantages of diverse combinations, adjustable structures, modifiable surface properties, and low prices. They are widely used in carbon-based resources (such as CO, CO 2 , CH 4 ) catalytic conversion, catalytic dehydrogenation, and catalytic oxidation reactions. Multi-metal oxides have gradually attracted attention due to their multiple metal active sites, synergistic effects between components, different valence states of metals, and interface structures between oxides.

[0003] The existing methods for preparing multi-metal oxide catalysts mainly include: (1) preparing multi-metal oxides by heat-treating multi-metal hydroxides in an inert atmosphere, wherein the multi-metal hydroxides are calcined in an inert atmosphere at a high temperature (≥800°C) to obtain pure phase high entropy oxides, and when the calcination temperature is reduced (<800°C), a mixed phase of multi-metal oxides is formed after calcination; (2) preparing multi-metal oxides by heat-treating mixed multi-metal salts, wherein the multi-metal salts are ball-milled and mixed to form powders, and then heat-treated to obtain multi-metal oxides; (3) preparing multi-metal oxides by thermally decomposing oleic acid-multi-metal complexes. (4) The multi-metal oxide is prepared by a hydrothermal method, which mainly involves dissolving a metal salt and an alkali in a solvent, and driving the metal cations to react with hydroxide ions by temperature and pressure to obtain a multi-metal oxide; (5) The multi-metal oxide is prepared by a solution-gel method, which mainly involves forming a gel with metal ions and ligands in a solvent, and then forming a multi-metal oxide after heat treatment.

[0004] In the above preparation method, for the preparation of polymetallic oxides by heat treatment of polymetallic hydroxides and mixed polymetallic salts in an inert atmosphere, polymetallic hydroxides and mixed polymetallic salts are used as precursors for heat treatment in an inert atmosphere, and the temperature is used to drive the entropy increase of the system to achieve uniform mixing of metals. Usually, a higher temperature is required. When high-temperature treatment is used, energy consumption is high and it is easy to cause metal agglomeration and low specific surface area. When low-temperature treatment is used, a polymetallic oxide mixed phase is often produced and the phases are separated. For the thermal decomposition of oleic acid-polymetallic complexes, the preparation process is cumbersome and the reaction activity is low. The catalysts synthesized by this method are mostly used in CO or CO 2Hydrogenation alcohol production process. For the hydrothermal method and the solution-gel method, the preparation cycle of these two methods is long, and the raw material cost of the solution-gel method is relatively high, which is not conducive to the large-scale production of catalysts. In addition, during the preparation of the catalyst by the solution-gel method, the active metal will be coated in other component metals, thus resulting in low catalyst activity.

[0005] The above method has the problems of long preparation cycle, high energy consumption and cost, insufficient mixing of oxide phases in the catalyst, and uneven distribution of surface metal elements. The product distribution of the provided catalyst in carbon-resource conversion (for example, carbon monoxide hydrogenation) is relatively wide and is dominated by heavy products (C 6 And above). Summary of the invention

[0006] The present invention aims to solve the problems of existing multi-metal oxide catalysts, such as the presence of a mixed phase, uneven distribution of metal elements on the catalyst surface resulting in insufficient catalytic activity, and low selectivity of light products in carbon-resource conversion, and to provide a multi-metal oxide catalyst and its preparation method and application.

[0007] To achieve the above object, the present invention provides a multi-metal oxide catalyst in a first aspect, the multi-metal oxide catalyst comprising: an oxide of a main metal element and an oxide of a co-metal element; wherein the main metal element is Fe;

[0008] The molar ratio of the main metal element: the auxiliary metal element is 10:(1-8);

[0009] The oxygen concentration in the multi-metal oxide catalyst is 17-22 wt %;

[0010] In the multi-metal oxide catalyst, the oxygen concentration in the region from the surface to a depth of 10 nm below the surface is 52-66 wt %;

[0011] The multimetal oxide catalyst has a non-mixed phase.

[0012] A second aspect of the present invention provides a method for preparing a multi-metal oxide catalyst, comprising: heat-treating a mixed metal hydroxide under a CO atmosphere to obtain a multi-metal oxide catalyst;

[0013] Wherein, the mixed metal hydroxide includes a hydroxide of a main metal element and a hydroxide of an auxiliary metal element; the main metal element is Fe;

[0014] The molar ratio of the main metal element: the auxiliary metal element is 10:(1-8).

[0015] The third aspect of the present invention provides a multi-metal oxide catalyst prepared by the method described in the second aspect.

[0016] The fourth aspect of the present invention provides use of the multi-metal oxide catalyst described in the first aspect or the third aspect in a carbon monoxide hydrogenation reaction.

[0017] The multi-metal oxide catalyst provided by the present invention is mainly composed of Fe oxide, has a non-mixed phase, and has a specific oxygen element concentration distribution. The surface metal elements of the catalyst are evenly distributed, and it has high catalytic activity in the carbon-resource conversion reaction, and the product distribution can be concentrated on the light component (C 5 and below). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 This is the XRD spectrum of the catalyst prepared in Example 1 of the present invention.

[0020] Figure 2 This is the TEM-Mapping image of the catalyst prepared in Example 1 of the present invention.

[0021] Figure 3 This is the XRD pattern of the catalyst prepared in Comparative Example 1 of the present invention.

[0022] Figure 4 This is the XRD pattern of the catalyst prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0023] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0024] The first aspect of the present invention provides a multi-metal oxide catalyst, the multi-metal oxide catalyst comprising: an oxide of a main metal element and an oxide of a co-metal element; wherein the main metal element is Fe;

[0025] The molar ratio of the main metal element: the auxiliary metal element is 10:(1-8);

[0026] The oxygen content of the multi-metal oxide catalyst is 17-22% by weight;

[0027] In the multi-metal oxide catalyst, the oxygen concentration in the region from the surface to a depth of 10 nm below the surface is 52-66 wt %;

[0028] The multimetal oxide catalyst has a non-mixed phase.

[0029] The multimetal oxide catalyst provided by the present invention contains an oxide of element Fe and an oxide of a metal promoter, wherein the oxide of Fe is the main component and satisfies the molar ratio of the main metal element to the metal promoter of 10:(1-8). The inventors of the present invention have found in their research that, under the condition of satisfying the above chemical composition, further, when the multimetal oxide has a non-mixed phase and the oxygen concentration in the multimetal oxide catalyst is 17-22% by weight, and at the same time, in the multimetal oxide, the oxygen concentration in the region from the surface to a depth of 10 nm below the surface is 52-66% by weight, the multimetal oxide can be used as a catalyst in a carbon-resource conversion reaction with high catalytic activity, and the product distribution is concentrated in the light component (C 5 and below).

[0030] In the present invention, the "non-mixed phase" is understood to mean that the oxides in the multi-metal oxide do not coexist in the form of a simple physical mixture, which can be manifested as a single spinel crystal phase in the XRD test spectrum of the multi-metal oxide, rather than the coexistence of crystal phases of multiple oxides.

[0031] According to the present invention, in the multi-metal oxide catalyst, the auxiliary metal element can be selected from at least one of Mg, Cu, Zn, Mn, Co, Ni, Cr and Ga. The use of the above-mentioned different auxiliary metal elements or their combinations can achieve selective regulation of CO hydrogenation reaction products.

[0032] According to the present invention, in the multi-metal oxide catalyst, preferably, the auxiliary metal element can be further selected from at least one of Mg, Cu, Zn, Mn and Co, which is more conducive to regulating the distribution of CO hydrogenation reaction products to concentrate on light components.

[0033] According to a preferred embodiment of the present invention, the auxiliary metal elements are Mg, Cu, Zn, Mn and Co.

[0034] According to the present invention, in the multi-metal oxide catalyst, preferably, the molar ratio of the main metal element: the auxiliary metal element is 10:(2.5-6).

[0035] According to a most preferred embodiment of the present invention, in the multi-metal oxide catalyst, the main metal element is Fe, and the auxiliary metal elements are Mg, Cu, Zn, Mn and Co, wherein the molar ratio of Fe:Mn:Mg:Co:Zn:Cu is 10:(0.5-1.2):(0.5-1.2):(0.5-1.2):(0.5-1.2):(0.5-1.2).

[0036] According to the present invention, the oxygen concentration in the surface region of the multi-metal oxide catalyst (i.e., the weight content ratio of the oxygen element in the surface region) is higher than the oxygen concentration in the internal region outside the surface region of the multi-metal oxide catalyst (i.e., the weight content ratio of the oxygen element in the internal region), which can make the catalyst have higher CO hydrogenation activity.

[0037] In the present invention, the surface region of the multi-metal oxide catalyst refers to the region from the surface to a depth of 10 nm below the surface of the multi-metal oxide catalyst.

[0038] According to the present invention, in the multi-metal oxide catalyst, preferably, the difference between the oxygen concentration in the region from the surface to a depth of 10 nm below the surface and the oxygen concentration in the multi-metal oxide catalyst is 33-48.5% by weight, which can significantly improve the CO hydrogenation reaction activity.

[0039] In the present invention, the oxygen concentration in the region from the surface to a depth of 10 nm below the surface of the multimetal oxide catalyst can be measured by X-ray photoelectron spectroscopy (XPS).

[0040] In the present invention, the oxygen concentration in the multi-metal oxide catalyst (ie, the weight content ratio of oxygen in all regions) can be measured using an oxygen, nitrogen and hydrogen analyzer and a pulse resistance inert gas combustion method.

[0041] In the present invention, the content and molar ratio of each metal element in the multi-metal oxide catalyst can be measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES).

[0042] According to the present invention, preferably, the specific surface area of ​​the multi-metal oxide catalyst is 10-100m 2 / g, more preferably 10-50m 2 / g.

[0043] According to the present invention, the specific surface area of ​​the multimetal oxide catalyst is expressed by N 2 Determination by physical adsorption-desorption method.

[0044] According to the present invention, the multi-metal oxide catalyst has uniform distribution of metal elements on the surface and rich surface oxygen content, which contributes to the catalyst having high CO catalytic activity, and the distribution of CO hydrogenation products is concentrated in light components.

[0045] In the present invention, the surface metal element distribution of the multi-metal oxide catalyst can be measured by X-ray photoelectron spectroscopy (XPS).

[0046] The multi-metal oxide catalyst provided by the present invention is used in carbon-resource conversion reactions (e.g., CO 2 Hydrogenation, CH 4 It has high catalytic activity in dry reforming and CO hydrogenation, etc., which can make the distribution of reaction products concentrated in light components (C 5 and below), especially in the carbon monoxide hydrogenation reaction, it can significantly increase C 1 -C 3 The yield of the product.

[0047] A second aspect of the present invention provides a method for preparing a multi-metal oxide catalyst, comprising: heat-treating a mixed metal hydroxide under a CO atmosphere to obtain a multi-metal oxide catalyst;

[0048] Wherein, the mixed metal hydroxide includes a hydroxide of a main metal element and a hydroxide of an auxiliary metal element; the main metal element is Fe;

[0049] The molar ratio of the main metal element: the auxiliary metal element is 10:(1-8).

[0050] According to the present invention, in the preparation method of the multi-metal oxide catalyst, in the mixed metal hydroxide, the auxiliary metal element can be selected from at least one of Mg, Cu, Zn, Mn, Co, Ni, Cr and Ga. The use of the above-mentioned different auxiliary metal elements or their combinations can achieve selective regulation of CO hydrogenation reaction products. Preferably, the auxiliary metal element can be further selected from at least one of Mg, Cu, Zn, Mn and Co, which is more conducive to regulating the CO hydrogenation reaction products to be concentrated in the light components.

[0051] According to a preferred embodiment of the present invention, in the preparation method of the multi-metal oxide catalyst, the auxiliary metal elements are Mg, Cu, Zn, Mn and Co. Preferably, in the mixed metal hydroxide, the molar ratio of Fe:Mn:Mg:Co:Zn:Cu is 10:(0.5-1.2):(0.5-1.2):(0.5-1.2):(0.5-1.2):(0.5-1.2).

[0052] According to the present invention, in the preparation method of the multi-metal oxide catalyst, in the mixed metal hydroxide, preferably, the molar ratio of the main metal element: the auxiliary metal element is 10: (2.5-6), which is more conducive to the formation of a non-mixed phase during the heat treatment process under a CO atmosphere.

[0053] According to the present invention, in the preparation method of the multi-metal oxide catalyst, the mixed metal hydroxide is a mixture of the hydroxide of the main metal element and the hydroxide of the auxiliary metal element. In the present invention, the source of the mixed metal hydroxide is broadly limited, and it can be obtained by fully mixing the commercially available or pre-prepared hydroxide of the main metal element and the hydroxide of the auxiliary metal element, or by jointly subjecting a salt containing the main metal element and a salt containing the auxiliary metal element to a precipitation reaction. Preferably, the preparation method of the mixed metal hydroxide may include: subjecting a salt solution containing the main metal element and the auxiliary metal element to a precipitation reaction with an alkaline solution, and then washing and drying the obtained solid phase product to obtain the mixed metal hydroxide.

[0054] According to the present invention, in the above method for preparing the mixed metal hydroxide, the salt solution containing the main metal element and the auxiliary metal element can be prepared by dissolving the salt containing the main metal element and the salt containing the auxiliary metal element in water. Preferably, in the salt solution containing the main metal element and the auxiliary metal element, the concentration of the metal salt (in terms of metal cation) is 0.05-4 mol / L.

[0055] According to the present invention, in the above method for preparing the mixed metal hydroxide, the alkali solution has a wide range of restrictions, as long as it can react with the metal cations in the salt solution containing the main metal element and the auxiliary metal element to generate a metal hydroxide precipitate. Preferably, the alkali solution can be selected from a NaOH solution or a KOH solution.

[0056] According to the present invention, in the above method for preparing the mixed metal hydroxide, preferably, the precipitation reaction is carried out at a pH of 12.5-13.5.

[0057] According to the present invention, in the above method for preparing the mixed metal hydroxide, the washing is relatively broad, and a conventional washing method can be used as long as the residual alkali solution can be removed. Preferably, the washing is performed by first washing with water and then washing with alcohol.

[0058] According to the present invention, in the above method for preparing the mixed metal hydroxide, the drying is limited to a wide range, as long as the washing solvent can be removed by drying. Preferably, the drying conditions include: a temperature of 60-80°C and a time of 6-12 hours.

[0059] According to the present invention, in the preparation method of the multi-metal oxide catalyst, before the heat treatment, the mixed metal hydroxide is preferably crushed, which is more conducive to heat transfer during the heat treatment and sufficient contact between CO and the mixed metal hydroxide. Preferably, the crushing treatment is carried out by grinding.

[0060] According to the present invention, in the preparation method of the multi-metal oxide catalyst, the mixed metal hydroxide is heat-treated under a CO atmosphere to obtain a multi-metal oxide with a non-mixed phase structure, and the preparation method can make the oxygen element concentration in the surface area of ​​the multi-metal oxide higher, forming a specific gradient with the oxygen element concentration in its internal area, and making the metal elements on the surface of the multi-metal uniformly distributed. Preferably, the conditions of the heat treatment include: temperature of 120-300°C and time of 0.5-24h.

[0061] The preparation method of the multi-metal oxide catalyst provided by the present invention uses a mixed metal hydroxide as a precursor, and heat-treats the precursor in a carbon monoxide atmosphere to make the prepared multi-metal oxide catalyst react with carbon resources (for example, CO 2 Hydrogenation, CH 4 It has high catalytic activity in dry reforming and CO hydrogenation, and the reaction products are concentrated in the light components (C 5 and below), especially in the CO hydrogenation reaction, the reaction product distribution can be concentrated on the light components, significantly improving C 1 -C 3 The yield of the product.

[0062] The third aspect of the present invention provides a multi-metal oxide catalyst prepared by the method described in the second aspect.

[0063] According to the present invention, the composition, structure and performance of the multi-metal oxide catalyst prepared by the method described in the second aspect are completely the same as those of the multi-metal oxide catalyst described in the first aspect, and will not be described in detail here.

[0064] The fourth aspect of the present invention provides use of the multi-metal oxide catalyst described in the first aspect or the third aspect in a carbon monoxide hydrogenation reaction.

[0065] The multi-metal oxide catalyst provided by the present invention has high catalytic activity in the carbon monoxide hydrogenation reaction, and can make the reaction product distribution concentrated in the light component, significantly improving the C 1 -C 3 The yield of the product, the C 1 -C 3 The product accounts for more than 70 mol%.

[0066] The present invention will be described in detail below by way of examples. In the following examples and comparative examples, unless otherwise specified, all are conventional methods; the reagents and materials, unless otherwise specified, can be obtained from commercial sources.

[0067] Example 1

[0068] Will Fe(NO 3 )·9H 2 O、Mn(NO 3 ) 2 ·4H 2 O、Mg(NO 3 ) 2 6H 2 O、Co(NO 3 ) 2 6H 2 O、Zn(NO 3 ) 2 6H 2 O, Cu(NO 3 ) 2 The materials are added in a molar ratio of 10:1:1:1:1:1, added to 50 mL of deionized water, and stirred evenly to obtain a mixed metal salt solution (wherein the total concentration of metal cations is 0.75 mol / L); the mixed metal salt solution is slowly added dropwise to a NaOH aqueous solution with a pH value of 13, and stirred to form a mixed system. During the dropping process, the pH value of the mixed system is adjusted to 13 with a 1M NaOH solution, and a precipitation reaction is performed. After the precipitation is complete, the solid phase product is separated by suction filtration, washed with deionized water for 3 times, and then washed with anhydrous ethanol for 3 times, and the washed product is placed in an oven and dried at 60° C. for 6 h to obtain a blocky mixed metal hydroxide;

[0069] The above mixed metal hydroxides were ground into powder, 2 g was weighed and placed in a vertical tube furnace, CO (200 mL / min) gas was introduced, the temperature was increased at a rate of 10°C / min, and calcined at 200°C for 1 h to obtain a multi-metal oxide catalyst (denoted as P1).

[0070] The composition of P1 is iron oxide, manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide, among which the molar ratio of Fe: Mn, Mg, Co, Zn, Cu is 10:1:1:1:1:1. The specific surface area of ​​P1 is 11.12m 2 / g.

[0071] The oxygen concentration in P1 was measured to be 17.43 wt %.

[0072] The oxygen concentration in the region from the surface to a depth of 10 nm below the surface of P1 was measured to be 65.57 wt %.

[0073] XRD test was performed on P1, and the results were as follows: Figure 1 ,from Figure 1 It can be seen that the crystal phase of P1 is mainly a spinel phase structure, and there are no obvious auxiliary metal oxide (manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide) impurity peaks, indicating that P1 has a non-mixed phase.

[0074] TEM-Mapping test was performed on P1, and the results are as follows Figure 2 ,from Figure 2 It can be seen that there is no obvious local enrichment of the metal elements on the surface of P1, and they are evenly distributed.

[0075] Example 2

[0076] Will Fe(NO 3 )·9H 2 O、Mn(NO 3 ) 2 ·4H 2 O、Mg(NO 3 ) 2 6H 2 O、Co(NO 3 ) 2 6H 2 O、Zn(NO 3 ) 2 6H 2 O, Cu(NO 3 ) 2 The materials are added in a molar ratio of 10:0.5:0.5:0.5:0.5:0.5, added to 50 mL of deionized water, and stirred evenly to obtain a mixed metal salt solution (wherein the total concentration of metal cations is 1.25 mol / L); the mixed metal salt solution is slowly added dropwise to a NaOH aqueous solution with a pH value of 13, and stirred to form a mixed system. During the dropping process, the pH value of the mixed system is adjusted to 13 by a 1M NaOH solution, and a precipitation reaction is carried out. After the precipitation is complete, the solid phase product is separated by suction filtration, and washed with deionized water for 3 times, and then washed with anhydrous ethanol for 3 times. The washed product is placed in an oven and dried at 60°C for 6 hours to obtain a blocky mixed metal hydroxide;

[0077] The above mixed metal hydroxides were ground into powder, 2 g was weighed and placed in a vertical tube furnace, CO (200 mL / min) gas was introduced, the temperature was increased at a rate of 10°C / min, and calcined at 150°C for 1 h to obtain a multi-metal oxide catalyst (denoted as P2).

[0078] P2 is composed of iron oxide, manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide, among which the molar ratio of Fe: Mn, Mg, Co, Zn, Cu is 10: 0.5: 0.5: 0.5: 0.5: 0.5.

[0079] XRD test shows that P2 is a spinel phase oxide with a non-mixed phase; TEM-Mapping test shows that the metal elements on the surface of P2 are evenly distributed. The specific surface area of ​​P2 is 14.27m 2 / g.

[0080] The oxygen concentration in P2 was measured to be 19.34 wt%.

[0081] The oxygen concentration in the region from the surface to a depth of 10 nm below the surface of P2 was measured to be 56.33 wt %.

[0082] Example 3

[0083] According to the method of Example 1, the only difference is that the calcination temperature is 150° C., and the other steps and conditions are the same as Example 1, to obtain a multi-metal oxide catalyst (denoted as P3).

[0084] P3 is composed of iron oxide, manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide, among which the molar ratio of Fe:Mn, Mg, Co, Zn, Cu is 10:1:1:1:1:1.

[0085] XRD test shows that P3 is a spinel phase oxide with a non-mixed phase; TEM-Mapping test shows that the metal elements on the surface of P3 are evenly distributed. The specific surface area of ​​P3 is 13.52m 2 / g.

[0086] The oxygen concentration in P3 was measured to be 19.52 wt %.

[0087] The oxygen concentration in the region from the surface to a depth of 10 nm below the surface of P3 was measured to be 55.33 wt %.

[0088] Example 4

[0089] According to the method of Example 1, the only difference is that the calcination temperature is 300° C., and the other steps and conditions are the same as Example 1, to obtain a multi-metal oxide catalyst (denoted as P4).

[0090] P4 is composed of iron oxide, manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide, among which the molar ratio of Fe:Mn, Mg, Co, Zn, Cu is 10:1:1:1:1:1.

[0091] XRD test shows that P4 is a spinel phase oxide with a non-mixed phase; TEM-Mapping test shows that the metal elements on the surface of P4 are evenly distributed. The specific surface area of ​​P4 is 10.34m 2 / g.

[0092] The oxygen content in P4 was measured to be 17.55 wt%.

[0093] The oxygen content in the region from the surface to a depth of 10 nm below the surface of P4 was measured to be 57.92 wt %.

[0094] Example 5

[0095] According to the method of Example 1, the only difference is that the calcination time is 24 hours, and the other steps and conditions are the same as Example 1, to obtain a multi-metal oxide catalyst (denoted as P5).

[0096] P5 is composed of iron oxide, manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide, among which the molar ratio of Fe:Mn, Mg, Co, Zn, Cu is 10:1:1:1:1:1.

[0097] XRD test shows that P5 is a spinel phase oxide with a non-mixed phase; TEM-Mapping test shows that the metal elements of P5 are evenly distributed. The specific surface area of ​​P5 is 11.32m 2 / g.

[0098] The oxygen concentration in P5 was measured to be 17.85 wt %.

[0099] The oxygen concentration in the region from the surface to a depth of 10 nm below the surface of P5 was measured to be 59.43 wt %.

[0100] Example 6

[0101] The method of Example 1 is followed except that Fe(NO 3 )·9H 2 O、Mn(NO 3 ) 2 ·4H 2 O、Mg(NO 3 ) 2 6H 2 O、Co(NO 3 ) 2 6H 2 O、Zn(NO 3 ) 2 6H 2 O, Cu(NO 3 ) 2 The molar ratio of is adjusted to 10:1:0.5:0.5:0.5:0.5, and the other steps and conditions are the same as those in Example 1 to obtain a multi-metal oxide catalyst (denoted as P6).

[0102] P6 is composed of iron oxide, manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide, among which the molar ratio of Fe: Mn, Mg, Co, Zn, Cu is 10:1:0.5:0.5:0.5:0.5.

[0103] XRD test shows that P6 is a spinel phase oxide with a non-mixed phase; TEM-Mapping test shows that the metal elements on the surface of P6 are evenly distributed. The specific surface area of ​​P3 is 11.62m 2 / g.

[0104] The oxygen concentration in P6 was measured to be 18.78 wt %.

[0105] The oxygen concentration in the region from the surface to a depth of 10 nm below the surface of P6 was measured to be 53.23 wt %.

[0106] Example 7

[0107] The method of Example 1 is followed except that Fe(NO 3 )·9H 2 O、Mn(NO 3 ) 2 ·4H 2 O、Mg(NO 3 ) 2 6H 2 O、Co(NO 3 ) 2 6H 2 O、Zn(NO 3 ) 2 6H 2 O, Cu(NO 3 ) 2 The molar ratio of is adjusted to 10:1:1.2:1.2:1.2:1.2, and the other steps and conditions are the same as those in Example 1 to obtain a multi-metal oxide catalyst (denoted as P7).

[0108] P7 is composed of iron oxide, manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide, among which the molar ratio of Fe:Mn, Mg, Co, Zn, Cu is 10:1:1.2:1.2:1.2:1.2.

[0109] XRD test shows that P7 is a spinel phase oxide with a non-mixed phase; TEM-Mapping test shows that the metal elements on the surface of P7 are evenly distributed. The specific surface area of ​​P7 is 13.67m 2 / g.

[0110] The oxygen concentration in P7 was measured to be 21.08 wt %.

[0111] The oxygen concentration in the region from the surface to a depth of 10 nm below the surface of P7 was measured to be 56.25 wt %.

[0112] Comparative Example 1

[0113] The method of Example 1 is followed except that the CO gas is replaced by an equal flow rate of N 2 The other steps and conditions were the same as those in Example 1 to obtain a multi-metal oxide catalyst (denoted as D1).

[0114] The composition of D1 is iron oxide, manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide, among which the molar ratio of Fe: Mn, Mg, Co, Zn, Cu is 10:1:1:1:1:1. The specific surface area of ​​D1 is 10.65m 2 / g.

[0115] The oxygen concentration in D1 was measured to be 20.33 wt %.

[0116] The oxygen content in the region from the surface to a depth of 10 nm below the surface in D1 was measured to be 52.77 wt %.

[0117] XRD test was performed on D1, and the results were as follows: Figure 3 ,from Figure 3 It can be seen that the crystal phase diffraction peaks of D1 show a variety of oxide characteristic peaks, indicating that D1 has a mixed phase of iron oxide, manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide.

[0118] Comparative Example 2

[0119] According to the method of Example 1, the only difference is that the CO gas is replaced by air of equal flow rate, and the other steps and conditions are the same as Example 1, to obtain a multi-metal oxide catalyst (denoted as D2).

[0120] The composition of D2 is iron oxide, manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide, among which the molar ratio of Fe: Mn, Mg, Co, Zn, Cu is 10:1:1:1:1:1. The specific surface area of ​​D2 is 7.08m 2 / g.

[0121] The oxygen content in D2 was measured to be 21.40 wt%.

[0122] The oxygen content in the region from the surface to a depth of 10 nm below the surface in D2 was measured to be 57.92 wt %.

[0123] XRD test was performed on D2, and the results were as follows: Figure 4 ,from Figure 4It can be seen that the crystal phase diffraction peaks of D2 show a variety of oxide characteristic peaks, indicating that D2 has a mixture phase of iron oxide, manganese oxide, magnesium oxide, cobalt oxide, zinc oxide and copper oxide.

[0124] Test Case

[0125] Evaluation of the performance of the catalyst for CO catalytic hydrogenation reaction:

[0126] The above multi-metal oxide catalysts P1-P5 and D1-D2 were used to conduct a carbon monoxide hydrogenation reaction test to compare the reaction performance of the catalysts. The apparatus and test conditions are as follows:

[0127] A high-pressure fixed-bed reaction gas (FID-2000, Hunan Huasi Instrument Co., Ltd.) was used, and a casing mode was adopted, with a quartz tube (outer diameter 14 mm, inner diameter 12 mm) as the inner lining and a reaction steel tube as the outer lining.

[0128] The reaction conditions of transient CO hydrogenation experiment were as follows: 0.5 g catalyst was mixed with 0.5 g quartz sand, and H 2 (90mL·min -1 ) at 350℃ for 1h at room pressure, with a syngas ratio of H 2 / CO / N 2 =45 / 45 / 10, pressure 1MPa, reaction temperature 280℃, synthesis gas space velocity 12000mL·g -1 ·hr -1 .

[0129] The test process is as follows:

[0130] (1) Evenly mix 0.5 g of 20-40 mesh catalyst and 0.5 g of 25-40 mesh quartz sand, slowly add them into the reaction tube, and use N 2 Raise the pressure to 1.1 MPa, perform a pressure test on the reaction tube, and check the air tightness of the reaction tube;

[0131] (2) Release the pressure of the reaction tube to normal pressure and wait for N 2 Drain and pass H 2 , the flow rate was set to 90 mL min -1 , program the temperature to 350℃, the heating rate is 10℃·min -1 , constant temperature reduction for 1h;

[0132] (3) Waiting for H 2 After the reduction is completed, when the temperature drops below 280°C, N 2Purge and cool down, close the needle valve at the tail gas outlet of the reaction tube to increase the pressure, set the back pressure valve to 1.1MPa, observe the pressure indication and the bubbles in the bubbler at the tail gas outlet, wait for the pressure indication to reach 1.1MPa, and the bubbler produces bubbles, then the pressure increase is over. At this time, set the temperature to the reaction temperature, i.e. 280℃, and the heating rate is 10℃·min -1 ;

[0133] (4) When the temperature of the reaction tube rises to the reaction temperature, switch the gas line to bypass and open the tail gas needle valve of the reaction tube to release the pressure and discharge N 2 At this time, the reaction tube is bypassed and is at 1.1 MPa, 280 °C and N 2 atmosphere; when the pressure drops to normal pressure, CO and H are introduced simultaneously 2 、N 2 , the flow rates were set to 45 mL min -1 、45mL·min -1 、10mL·min -1 ; Slowly adjust the three-way gas outlet pressure until the reaction tube pressure reaches 1.1MPa; wait for bubbles to form in the bubbler, indicating that the side branch pressure boost operation is completed; perform online analysis of the side branch mixed gas composition ratio through chromatography, and calibrate the mixed gas until the ratio remains almost unchanged, indicating that the gas mixing is uniform;

[0134] (5) When the gas line is switched from the side branch to the reaction tube, the time when the tail gas produced after the mixed gas begins to contact the catalyst and enters the chromatogram is called dead time. This period of time is used to determine the time required for the first mixed gas to contact and react with the surface of the fresh catalyst. It is determined by the timing of a stopwatch and the start of bubble generation by the bubbler, and the chromatogram peak is used as auxiliary evidence.

[0135] (6) When the gas line is switched from the side branch to the reaction tube, a stopwatch is used to time and calculate the dead time, and the chromatographic online injection is used to analyze the transient CO hydrogenation reaction performance of the catalyst.

[0136] The contents of various hydrocarbon components in the reaction product were determined online using Shimadzu gas chromatography (model GC2014C). The results are shown in Table 1.

[0137] Table 1

[0138] catalyst CO conversion rate / % <![CDATA[C 1 -C 3 / mol%]]> <![CDATA[C 4 / mol%]]> <![CDATA[C 5 + / mol%]]> P1 78.13 86.13 6.33 7.54 P2 73.58 80.04 8.34 11.62 P3 68.34 75.27 6.01 18.72 P4 65.54 77.98 5.0 17.02 P5 63.22 72.24 7.35 20.41 P6 74.09 81.08 9.24 9.68 P7 76.67 84.56 7.21 8.23 D1 53.18 49.89 7.68 42.42 D2 42.79 58.15 4.94 36.9

[0139] As can be seen from Table 1, under the above test conditions, catalysts P1-P7 have high catalytic activity in the carbon monoxide hydrogenation reaction, with a CO conversion rate of more than 63%, and the hydrocarbon products obtained by hydrogenation are concentrated in the light components, among which C 1 -C 3 The light component accounts for more than 70 mol%, C 5 + The product selectivity is low.

[0140] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A multi-metal oxide catalyst, characterized in that: The multi-metal oxide catalyst comprises: an oxide of a main metal element and an oxide of an auxiliary metal element; wherein the main metal element is Fe; The molar ratio of the main metal element: the auxiliary metal element is 10:(1-8); The oxygen concentration in the multi-metal oxide catalyst is 17-22 wt %; In the multi-metal oxide catalyst, the oxygen concentration in the region from the surface to a depth of 10 nm below the surface is 52-66 wt %; The multimetal oxide catalyst has a non-mixed phase.

2. The multimetal oxide catalyst according to claim 1, wherein The auxiliary metal element is selected from at least one of Mg, Cu, Zn, Mn, Co, Ni, Cr and Ga, preferably at least one of Mg, Cu, Zn, Mn and Co.

3. The multimetal oxide catalyst according to claim 1 or 2, wherein: The molar ratio of the main metal element: the auxiliary metal element is 10:(2.5-6).

4. The multimetal oxide catalyst according to any one of claims 1 to 3, wherein: In the multimetal oxide catalyst, the difference between the concentration of oxygen in a region from the surface to a depth of 10 nm below the surface and the concentration of oxygen in the multimetal oxide catalyst is 33-48.5 wt %.

5. The multimetal oxide catalyst according to any one of claims 1 to 4, wherein: The specific surface area of ​​the multi-metal oxide catalyst is 10-100m 2 / g, preferably 10-50m 2 / g.

6. A method for preparing a multi-metal oxide catalyst, characterized in that: include: The mixed metal hydroxide is heat-treated under a CO atmosphere to obtain a multi-metal oxide catalyst; Wherein, the mixed metal hydroxide includes a hydroxide of a main metal element and a hydroxide of an auxiliary metal element; the main metal element is Fe; The molar ratio of the main metal element: the auxiliary metal element is 10:(1-8).

7. The preparation method according to claim 6, wherein: The auxiliary metal element is selected from at least one of Mg, Cu, Zn, Mn, Co, Ni, Cr and Ga; And / or, the heat treatment conditions include: temperature of 150-300° C. and time of 0.5-24 h.

8. The preparation method according to claim 6 or 7, wherein: The preparation method of the mixed metal hydroxide comprises: subjecting a salt solution containing the main metal element and the auxiliary metal element to a precipitation reaction with an alkali solution, and then washing and drying the obtained solid phase product to obtain the mixed metal hydroxide.

9. A multimetal oxide catalyst prepared by the method according to any one of claims 6 to 8.

10. Use of the multimetal oxide catalyst according to any one of claims 1 to 5 and 9 in the carbon monoxide hydrogenation reaction.

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