CN112705203B - Composite oxide material and cobalt-based catalyst, and preparation methods and applications thereof - Google Patents

Abstract

The present invention relates to the field of catalysts, and in particular to a composite oxide material and a cobalt-based catalyst and a preparation method and application thereof. The composite oxide material preparation method comprises the following steps: (I1) hydrothermally reacting a first mixture containing a silicon source, a zirconium source, a titanium source, a precipitant and a first solvent to obtain a first solid; (I2) preparing a second mixture containing the first solid, a second solvent and a cobalt source into a slurry, and drying and calcining the slurry; wherein, relative to 100 parts by weight of the Si source, the amount of the Zr source is 1-15 parts by weight, the amount of the Ti source is 2-40 parts by weight, and the content of the Co element is 0.5-20 parts by weight. The composite oxide material of the present invention has comprehensive properties such as suitable specific surface area, pore structure, particle size distribution and anti-wear performance, and the cobalt-based catalyst of the present invention has high catalytic activity, low methane selectivity and good stability when used in the Fischer-Tropsch synthesis reaction.

Description

Composite oxide material and cobalt-based catalyst and preparation method and application thereof

Technical Field

The present invention relates to the field of catalysts, and in particular to a composite oxide material, a method for preparing the composite oxide material, a composite oxide material obtained by the preparation method, a cobalt-based catalyst containing the composite oxide material, a method for preparing the cobalt-based catalyst, and applications of the cobalt-based catalyst.

Background technique

Fischer-Tropsch synthesis is an important way to convert coal or natural gas into liquid fuels and chemicals. It is also an effective way to achieve clean utilization of coal in my country, alleviate the shortage of oil resources and ensure energy security. The performance of Fischer-Tropsch synthesis catalysts directly determines the economic efficiency of the Fischer-Tropsch synthesis process. Therefore, catalysts with high activity, high selectivity and stable performance are the research focus of Fischer-Tropsch synthesis.

Currently, the most widely used Fischer-Tropsch synthesis catalysts in the industrial field are iron-based catalysts and cobalt-based catalysts.

my country has abundant iron resources with low cost, which can be used as a catalyst for the preparation of low-carbon olefins and high-octane gasoline, and is suitable for a wide range of syngas compositions and operating temperatures. However, the defects of iron-based catalysts are: they have high activity in the water-gas shift reaction and poor chain growth ability, and are prone to carbon deposition and deactivation when the reaction temperature is too high.

In contrast, cobalt-based catalysts have higher Fischer-Tropsch reaction activity and high selectivity for heavy straight-chain saturated hydrocarbons, are insensitive to water-gas shift, have wide adaptability to raw materials, are highly adjustable to products, and are not easily deactivated by carbon deposition. Therefore, cobalt-based catalysts have received extensive attention in this field. However, cobalt-based catalysts usually have the following shortcomings: the characteristics of the Co element itself make it difficult to reconcile the reduction degree and dispersion of its particles, resulting in the catalytic activity and selectivity of the catalyst being still not ideal; and the wear resistance of cobalt-based catalysts still needs to be improved, especially the slurry bed reaction has high requirements for the wear resistance of the catalyst.

Therefore, it is of great significance to study a cobalt-based catalyst with better comprehensive performance for the Fischer-Tropsch synthesis reaction.

Summary of the invention

The purpose of the present invention is to further improve the catalytic activity of cobalt-based catalysts, and to provide a composite oxide material, a method for preparing the composite oxide material, a composite oxide material obtained by the preparation method, a cobalt-based catalyst containing the composite oxide material, a method for preparing the cobalt-based catalyst, and applications of the cobalt-based catalyst.

The first aspect of the present invention provides a composite oxide material, which contains Si, Zr, Ti and Co elements; relative to 100 parts by weight of the Si element calculated as _SiO2 , the content of the Zr element calculated as _ZrO2 is 1-15 parts by weight, the content of the Ti element calculated as _TiO2 is 2-40 parts by weight, and the content of the Co element calculated as Co is 0.5-20 parts by weight; the composite oxide material is spherical and has a particle size of 1-500μm.

A second aspect of the present invention provides a method for preparing a composite oxide material, the method comprising the following steps:

(I1) subjecting a first mixture containing a silicon source, a zirconium source, a titanium source, a precipitant and a first solvent to a hydrothermal reaction, and subjecting a material obtained by the hydrothermal reaction to solid-liquid separation to obtain a first solid;

(I2) preparing a second mixture containing the first solid, a second solvent and a cobalt source into a slurry, and drying and calcining the slurry;

Wherein, relative to 100 parts by weight of the Si source calculated as _SiO2 , the amount of the Zr source calculated as _ZrO2 is 1-15 parts by weight, the amount of the Ti source calculated as _TiO2 is 2-40 parts by weight, and the amount of the Co source calculated as Co is 0.5-20 parts by weight.

The third aspect of the present invention provides a composite oxide material prepared by the method described in the second aspect of the present invention.

The fourth aspect of the present invention provides a cobalt-based catalyst, which includes a composite oxide material and a main active component and a co-active component loaded on the composite oxide material. The composite oxide material is the composite oxide material described in the first aspect or the third aspect of the present invention.

The fifth aspect of the present invention provides a method for preparing the cobalt-based catalyst according to the fourth aspect of the present invention, characterized in that the method comprises the following steps:

(II1) preparing an impregnation solution containing a main active ingredient precursor and a co-active ingredient precursor;

(II2) Spraying or impregnating the composite oxide material described in the first or third aspect of the present invention with the impregnation solution, and calcining the obtained solid phase.

The sixth aspect of the present invention provides the use of the composite oxide material described in the first aspect or the third aspect of the present invention or the cobalt-based catalyst described in the fourth aspect in a Fischer-Tropsch synthesis reaction.

Through the above technical solution, the present invention has at least the following advantages:

(1) The composite oxide material of the present invention has a higher specific surface area and a more suitable pore size;

(2) The composite oxide material of the present invention has uniform particle size distribution and strong wear resistance;

(3) The cobalt-based catalyst of the present invention has excellent hydrothermal stability;

(4) The cobalt-based catalyst of the present invention has higher catalytic activity (CO conversion rate), lower methane selectivity and better stability when used in the Fischer-Tropsch synthesis reaction.

Other features and advantages of the present invention will be described in detail in the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

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:

FIG. 1 is a graph showing the change in CO conversion rate of the catalysts prepared in Example 1 and Comparative Examples 1-3 in a hydrothermal reaction as a function of Fischer-Tropsch reaction time.

Detailed ways

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 regarded as specifically disclosed in this article.

The first aspect of the present invention provides a composite oxide material, wherein the composite oxide material contains Si, Zr, Ti and Co; relative to 100 parts by weight of the Si element calculated as _SiO2 , the content of the Zr element calculated as _ZrO2 is 1-15 parts by weight, the content of the Ti element calculated as _TiO2 is 2-40 parts by weight, and the content of the Co element calculated as Co is 0.5-20 parts by weight; the composite oxide material is spherical and has a particle size of 1-500 μm. Wherein, the Si element, Zr element, Ti element and Co element exist in the composite oxide material in the form of oxides respectively.

The inventors of the present invention have found that by matching Si, Zr, Ti and Co elements in the above ratio, the composite oxide material can have good physical (e.g., appropriate specific surface area and pore structure) and chemical (e.g., good hydrothermal stability) properties. The inventors of the present invention have found that by matching Si, Zr, Ti and Co elements in the above ratio, the active components can obtain good reduction and dispersion.

In addition, since the catalyst particles are prone to wear and breakage during the slurry bed reaction, on the one hand, it will make it difficult to separate the product wax from the catalyst, affecting the product quality, and on the other hand, the loss of the catalyst will cause the catalyst activity to decrease, so higher requirements are placed on the catalyst's anti-wear performance. Therefore, the inventors of the present invention have found that the spherical composite oxide material within the above-mentioned particle size range can have the best anti-wear performance and can have both good fluidity and wear resistance. It should be noted that the concept of "spherical" described in the present invention is interpreted according to the conventional understanding of sphere in the chemical industry, and the concept of standard sphere in the geometric sense cannot be used to limit the present invention. In principle, all shapes that are considered to be similar to spheres belong to the protection scope of this application.

In order to further improve the catalytic activity of the prepared cobalt-based catalyst, preferably, in the composite oxide material, relative to 100 parts by weight of the Si element calculated as _SiO2 , the content of the Zr element calculated as _ZrO2 is 2-10 parts by weight, the content of the Ti element calculated as _TiO2 is 5-25 parts by weight, and the content of the Co element calculated as Co is 5-15 parts by weight; more preferably, relative to 100 parts by weight of the Si element calculated as _SiO2 , the content of the Zr element calculated as _ZrO2 is 3-8 parts by weight, the content of the Ti element calculated as _TiO2 is 6-12 parts by weight, and the content of the Co element calculated as Co is 8-12 parts by weight.

In order to further improve the fluidity and wear resistance of the prepared composite oxide material, preferably, the particle size of the composite oxide material is 38-150 μm; more preferably 60-120 μm. In the present invention, the term "particle size" refers to the geometric diameter of each spherical particle of the composite oxide material, which is measured by a Malvern Mastersizer 3000 laser particle size analyzer in the present invention.

Preferably, the composite oxide material with a particle size in the range of 38-150 μm accounts for more than 85% of the total weight of the composite oxide material, more preferably more than 90%. Therefore, the composite oxide material has a good particle size distribution.

The composite oxide material with the above specific content ratio of the present invention can have better physical properties (such as specific surface area and pore structure in a more suitable range). Preferably, the specific surface area of the composite oxide material is ^120-190m2 /g, and the average pore size is 10-25nm; more preferably, the specific surface area of the composite oxide material is ^150-185m2 /g, and the average pore size is 15-20nm.

A second aspect of the present invention provides a method for preparing a composite oxide material, the method comprising the following steps:

(I1) subjecting a first mixture containing a silicon source, a zirconium source, a titanium source, a precipitant and a first solvent to a hydrothermal reaction, and subjecting a material obtained by the hydrothermal reaction to solid-liquid separation to obtain a first solid;

(I2) preparing a second mixture containing the first solid, a second solvent and a cobalt source into a slurry, and drying and calcining the slurry;

Wherein, relative to 100 parts by weight of the Si source calculated as _SiO2 , the amount of the Zr source calculated as _ZrO2 is 1-15 parts by weight, the amount of the Ti source calculated as _TiO2 is 2-40 parts by weight, and the content of the Co element calculated as Co is 0.5-20 parts by weight.

The amounts of the silicon source, zirconium source, titanium source and cobalt source mentioned above can enable the active components to obtain better reduction degree and dispersion, thereby improving the catalytic activity of the cobalt-based catalyst prepared by the composite oxide material. Preferably, relative to 100 parts by weight of the silicon source calculated as _SiO2 , the amount of the Zr source calculated as _ZrO2 is 2-10 parts by weight, the amount of the Ti source calculated as _TiO2 is 5-25 parts by weight, and the amount of the Co source calculated as Co is 5-15 parts by weight; further preferably, relative to 100 parts by weight of the silicon source calculated as _SiO2 , the amount of the zirconium source calculated as _ZrO2 is 3-8 parts by weight, the amount of the titanium source calculated as _TiO2 is 6-12 parts by weight, and the amount of the cobalt source calculated as Co is 8-12 parts by weight.

Preferably, the amount of the precipitant is 5-15 parts by weight, more preferably 8-12 parts by weight, relative to 100 parts by weight of the silicon source calculated as _SiO2 .

Preferably, the silicon source is selected from one or more of silicon dioxide and silica sol; more preferably, the silicon source is powdered and/or sol-state silicon dioxide. Preferably, the particle size of the powdered silicon dioxide is 50-200 nm.

Preferably, the titanium source is selected from one or more of titanium tetrachloride, metatitanic acid, titanium oxide, titanium sulfate, titanium ethylene propoxide, tetrabutyl titanate and isopropyl titanate.

Preferably, the zirconium source is selected from one or more of zirconium oxynitrate, zirconium oxychloride and zirconium nitrate.

Preferably, the cobalt source is selected from one or more of cobalt hydroxide and cobalt oxide; more preferably, the cobalt source is cobalt hydroxide. The inventors of the present invention have found that when the cobalt source is cobalt hydroxide (Co(OH) ₂ ), the methane selectivity of the prepared cobalt-based catalyst can be significantly reduced.

Preferably, the precipitant may be a homogeneous precipitant, preferably urea and/or hexamethylenetetramine, most preferably urea.

In step (I1), the conditions of the hydrothermal reaction can be carried out in a conventional manner in the art. Preferably, the conditions of the hydrothermal reaction include: a temperature of 120-250°C and a time of 10-30h; more preferably, the conditions of the hydrothermal reaction include: a temperature of 150-200°C and a time of 10-20h.

In step (I1), the amount of the first solvent in the first mixture is not particularly limited, as long as it can provide a sufficient reaction environment for the reaction. Preferably, the weight of the first solvent accounts for 50-85% by weight of the total weight of the first mixture.

In step (I2), the amount of the second solvent in the second mixture is not particularly limited, as long as it can provide a sufficient mixing environment. Preferably, the weight of the second solvent accounts for 35-70 weight % of the total weight of the second mixture.

There is no particular limitation on the specific selection of the first solvent and the second solvent, as long as they have no significant effect on the reaction, and deionized water is preferred.

In step (I2), in order to achieve the composite oxide material having the characteristics of the particle size range, particle size distribution, etc. described in the present invention, preferably, the drying is spray drying.

Preferably, the spray drying conditions include: an inlet temperature of 250-400°C, and an outlet temperature of 100-250°C; more preferably, the spray drying conditions include: an inlet temperature of 300-350°C, and an outlet temperature of 150-200°C.

In step (I2), preferably, the calcination conditions include: temperature of 400-500°C, time of 3-6h; more preferably, the calcination conditions include: temperature of 420-480°C, time of 4-5h.

The third aspect of the present invention provides a composite oxide material prepared by the method described in the second aspect of the present invention.

According to the method of the second aspect, a first solid containing a silicon source, a zirconium source and a titanium source is first prepared by a hydrothermal reaction, and then the first solid is mixed with a cobalt source. The composite oxide material prepared in this step-by-step manner can have good physical and chemical properties, can make the active components obtain good reduction degree and dispersion, and the prepared cobalt-based catalyst can have good catalytic activity.

The specific parameters and characteristics of the composite oxide material of the third aspect of the present invention are the same as those of the composite oxide material of the first aspect of the present invention, and will not be described in detail herein.

The fourth aspect of the present invention provides a cobalt-based catalyst, which includes a composite oxide material and a main active component and a co-active component loaded on the composite oxide material. The composite oxide material is the composite oxide material described in the first aspect or the third aspect of the present invention.

In order to further improve the catalytic activity of the cobalt-based catalyst, preferably, the main active component is Co element, and the auxiliary active components include Mn element and precious metal elements.

Preferably, relative to 100 parts by weight of Si element in the composite oxide material calculated as _SiO2 , the sum of the contents of the main active ingredient calculated as element and the auxiliary active ingredient calculated as element is 2-20 parts by weight, more preferably 6-15 parts by weight.

The limitation on the content of Co element in the fourth aspect of the present invention does not include the amount of Co element in the first, second and third aspects of the present invention. For the convenience of description, the "Co element as the main active component" in the fourth aspect of the present invention does not include the Co element in the first, second and third aspects of the present invention; however, it should be noted that Co in the carrier also plays the role of the main active component.

In the present invention, unless otherwise specified, the term "support" refers to the composite oxide material.

Preferably, relative to 100 parts by weight of Si element in the composite oxide material calculated as SiO ₂ , the content of the Co element as the main active component is 2-15 parts by weight, the content of the Mn element is 0.5-5 parts by weight, and the content of the precious metal element is 0.1-2 parts by weight; more preferably, relative to 100 parts by weight of Si element in the composite oxide material calculated as SiO ₂ , the content of the Co element as the main active component is 5-12 parts by weight, the content of the Mn element is 1-3 parts by weight, and the content of the precious metal element is 0.2-1 parts by weight. In this paragraph, the Co element refers only to the Co element as the main active component, and does not include the Co element in the carrier.

According to the specific implementation mode of the present invention in which the main active ingredient is the Co element, a part of the Co is combined with the interior of the carrier, and interacts and cooperates with the Si element, the Zr element and the Ti element; while the other part of the Co is loaded on the surface of the carrier, and interacts and cooperates with the auxiliary active ingredients; this distribution mode of Co can effectively improve the Fischer-Tropsch synthesis reaction performance of the cobalt-based catalyst.

Preferably, relative to 100 parts by weight of Si element in the composite oxide material calculated as _SiO2 , the sum of the content of the Co element as the main active component and the content of the Co element in the carrier is 10-50 parts by weight, more preferably 10-30 parts by weight, and most preferably 15-25 parts by weight.

Preferably, the noble metal element is selected from one or more of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum (Pt); more preferably, the noble metal element is ruthenium and/or platinum.

The fifth aspect of the present invention provides a method for preparing the cobalt-based catalyst according to the fourth aspect of the present invention, characterized in that the method comprises the following steps:

(II1) preparing an impregnation solution containing a main active ingredient precursor and a co-active ingredient precursor;

(II2) Spraying or impregnating the composite oxide material described in the first or third aspect of the present invention with the impregnation solution, and calcining the obtained solid phase.

In step (II1), the main active ingredient precursor is a cobalt source, and the auxiliary active ingredient precursor includes a manganese source and a noble metal source.

Similar to the description of the fourth aspect of the present invention, the "main active component precursor" in the fifth aspect of the present invention also does not include the "Co source" in the second aspect of the present invention.

The amounts of the main active ingredient precursor and the auxiliary active ingredient precursor are all calculated by element weight, for example, the cobalt source is calculated by Co element, the manganese source is calculated by Mn element, and the noble metal source is calculated by noble metal element.

The specific components and amounts of the main active ingredient precursor and the auxiliary active ingredient precursor measured by element weight are the same as the specific components and amounts of the active ingredient in the fourth aspect of the present invention measured by element weight, and will not be repeated here.

Preferably, the cobalt source as a precursor of the main active ingredient is selected from one or more of cobalt nitrate, cobalt acetate, cobalt chloride and cobalt sulfate.

Preferably, the manganese source is selected from one or more soluble salts of manganese; more preferably, the manganese source is selected from one or more of manganese nitrate, manganese acetate and manganese chloride.

Preferably, the noble metal source is one or more of nitrates, chlorides and sulfates of the noble metal elements.

Preferably, the noble metal element is selected from one or more of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum (Pt). The noble metal element is most preferably ruthenium and/or platinum.

In step (II2), before the calcination, the solid phase obtained by spraying or impregnation is aged at 10-40° C. for 2-6 h.

In step (II2), in order to further improve the catalytic activity of the prepared cobalt-based catalyst, preferably, the calcination temperature rising program includes: in the first stage, heating from 20-50°C to 100-150°C at a rate of 0.5-5°C/min and then maintaining for 8-15h; in the second stage, heating to 160-180°C at a rate of 0.5-5°C/min and then maintaining for 1-7h; in the third stage, heating to 220-300°C at a rate of 0.5-5°C/min and then maintaining for 2-10h; more preferably, the calcination temperature rising program includes: in the first stage, heating from 20-50°C to 110-120°C at a rate of 1-2°C/min and then maintaining for 10-12h; in the second stage, heating to 180-200°C at a rate of 1-2°C/min and then maintaining for 3-5h; in the third stage, heating to 230-280°C at a rate of 1-2°C/min and then maintaining for 5-8h.

In step (II2), the spraying can be carried out in a conventional manner in the art. Preferably, the spraying conditions include: temperature of 15-35°C and time of 2-6 hours; more preferably, the spraying conditions include: temperature of 20-30°C and time of 4-5 hours.

In step (II2), the impregnation can be carried out in a conventional manner in the art. Preferably, the impregnation conditions include: temperature of 15-35°C, time of 2-6 hours; more preferably, the impregnation conditions include: temperature of 20-30°C, time of 4-5 hours.

The sixth aspect of the present invention provides the use of the composite oxide material described in the first aspect or the third aspect of the present invention or the cobalt-based catalyst described in the fourth aspect in the Fischer-Tropsch synthesis reaction. The application method can be the same as the application method of conventional cobalt-based catalysts in the Fischer-Tropsch synthesis reaction, which will not be repeated here.

The present invention will be described in detail below through examples.

Embodiment 1:

(1) Preparation of carrier:

26.15g of ZrOCl ₂ ·8H ₂ O (equivalent to 10g in terms of ZrO ₂ ) and 20g of urea were weighed and dissolved in 500ml of deionized water to obtain solution A. 125.16ml of 2mol/L TiCl ₄ (i.e. 47.50g TiCl ₄ , equivalent to 20g in terms of TiO ₂ ) was dropped into solution A to obtain solution B. 200g of silicon oxide powder (equivalent to 200g in terms of SiO ₂ , purchased from Tianjin Chemical Research Institute, the same below) was weighed and placed into solution B and then transferred into a hydrothermal autoclave with a polytetrafluoroethylene lining. The hydrothermal autoclave was heated to 180°C and kept at a constant temperature for 15h. The hydrothermal slurry was then filtered and washed with deionized water for 3 times. The filter cake obtained by washing was mixed with 300 ml of deionized water and 31.56 g of Co(OH) ₂ (equivalent to 20 g of Co) and slurried. The slurry was dried and formed in a spray dryer (inlet temperature was 300°C, outlet temperature was 200°C, the same below). The obtained granular powder was calcined at 450°C for 4 hours to obtain a carrier marked as Z-1.

(2) Preparation of catalyst:

76.78 g of Co(NO ₃ ) ₂ ·6H ₂ O (equivalent to 15.55 g in terms of Co) was weighed and dissolved in 300 ml of deionized water, and 15.55 g of Ru(NO)(NO ₃ ) ₃ aqueous solution (Ru concentration of 5 wt %) (equivalent to 0.78 g in terms of Ru) and 20.26 g of 50 wt % Mn(NO ₃ ) ₂ aqueous solution (equivalent to 3.11 g in terms of Mn) were added, and the mixture was mixed well to prepare the impregnation solution. Weigh 200g of the carrier prepared in step (1) above, put it into a coating machine, and spray the impregnation liquid while continuously rolling. During the spraying process, the speed of the coating machine is set to 60r/min. After the spraying is completed, the sample is kept at 30°C for 2h in the coating machine, and then transferred to a muffle furnace for calcination in a flowing air atmosphere. The heating program is: heating to 120°C at 1°C/min and keeping it for 10 hours, then heating to 180°C at 1°C/min and keeping it for 4 hours, and then heating to 250°C at 1°C/min and keeping it for 8 hours. The catalyst C1 of the present invention is obtained.

Embodiment 2:

(1) Preparation of carrier:

15.69 g of ZrOCl ₂ ·8H ₂ O (equivalent to 6 g in terms of ZrO ₂ ) and 21 g of urea were weighed and dissolved in 500 ml of deionized water to obtain solution A. 150.19 ml of 2 mol/L TiCl ₄ (equivalent to 24 g in terms of TiO ₂ ) was dropped into solution A to obtain solution B. 200 g of silicon oxide powder (200 g in terms of SiO ₂ ) was weighed and placed in solution B and then transferred to a hydrothermal kettle lined with polytetrafluoroethylene. The hydrothermal kettle was heated to 200°C and kept at a constant temperature for 10 hours. The slurry produced by the hydrothermal reaction was then filtered and washed with deionized water for 3 times. The filter cake obtained by washing was mixed with 300 ml of deionized water and 31.56 g of Co(OH) ₂ (equivalent to 20 g in terms of Co) and slurried. The slurry was dried and formed in a spray dryer. The obtained granular powder was calcined at 420°C for 5 hours to obtain a carrier marked as Z-2.

(2) Preparation of catalyst:

76.78 g of Co(NO ₃ ) ₂ ·6H ₂ O (equivalent to 15.55 g in terms of Co) was weighed and dissolved in 300 ml of deionized water, and 18.66 g of Ru(NO)(NO ₃ ) ₃ aqueous solution (Ru concentration of 5 wt %) (equivalent to 0.933 g in terms of Ru) and 15.19 g of 50 wt % Mn(NO ₃ ) ₂ aqueous solution (equivalent to 2.33 g in terms of Mn) were added, and the mixture was mixed well to prepare the impregnation solution. Weigh 200g of the carrier prepared in step (1) above, put it into a coating machine, and spray the impregnation liquid while continuously rolling. During the spraying process, the speed of the coating machine is set to 60r/min. After the spraying is completed, the sample is kept at 30°C for 2h in the coating machine, and then transferred to a muffle furnace for calcination in a flowing air atmosphere. The heating program is: heating to 120°C at 1°C/min and keeping it for 10 hours, then heating to 180°C at 1°C/min and keeping it for 4 hours, and then heating to 230°C at 1°C/min and keeping it for 8 hours. The catalyst C2 of the present invention is obtained.

Embodiment 3:

(1) Preparation of carrier:

41.84 g of ZrOCl ₂ ·8H ₂ O (equivalent to 16 g in terms of ZrO ₂ ) and 17 g of urea were weighed and dissolved in 500 ml of deionized water to obtain solution A. 75.10 ml of 2 mol/L TiCl ₄ (equivalent to 12 g in terms of TiO ₂ ) was dropped into solution A to obtain solution B. 200 g of silicon oxide powder (200 g in terms of SiO ₂ ) was weighed and placed in solution B and then transferred to a hydrothermal kettle lined with polytetrafluoroethylene. The hydrothermal kettle was heated to 150°C and kept at a constant temperature for 20 hours. The slurry produced by the hydrothermal reaction was then filtered and washed with deionized water for 3 times. The filter cake obtained by washing was mixed with 300 ml of deionized water and 31.56 g of Co(OH) ₂ (equivalent to 20 g in terms of Co) and slurried. The slurry was dried and formed in a spray dryer. The obtained granular powder was calcined at 480°C for 4 hours to obtain a carrier marked as Z-3.

(2) Preparation of catalyst:

77.39 g Co(NO ₃ ) ₂ ·6H ₂ O (equivalent to 15.67 g in terms of Co) was weighed and dissolved in 300 ml of deionized water, and 12.54 g of Ru(NO)(NO ₃ ) ₃ aqueous solution (Ru concentration of 5 wt %) (equivalent to 0.627 g in terms of Ru) and 25.52 g of 50 wt % Mn(NO ₃ ) ₂ aqueous solution (equivalent to 3.92 g in terms of Mn) were added, and the mixture was mixed well to prepare the impregnation solution. Weigh 200g of the carrier prepared in step (1) above, put it into a coating machine, and spray the impregnation liquid while continuously rolling. During the spraying process, the speed of the coating machine is set to 60r/min. After the spraying is completed, the sample is kept at 30°C for 2h in the coating machine, and then transferred to a muffle furnace for calcination in a flowing air atmosphere. The heating program is: heating to 120°C at 1°C/min and keeping it for 10 hours, then heating to 180°C at 1°C/min and keeping it for 4 hours, and then heating to 280°C at 1°C/min and keeping it for 8 hours. The catalyst C3 of the present invention is obtained.

Embodiment 4:

(1) Preparation of carrier:

21.66 g of ZrO(NO ₃ ) ₂ ·2H ₂ O (9.98 g in terms of ZrO ₂ ) and 19 g of urea were weighed and dissolved in 500 ml of deionized water to obtain solution A. 200 g of silicon oxide powder (200 g in terms of SiO ₂ ) and 20 g of titanium oxide powder (20 g in terms of TiO ₂ ) were weighed and placed in solution A and then transferred to a hydrothermal kettle lined with polytetrafluoroethylene. The hydrothermal kettle was heated to 180° C. and kept at a constant temperature for 15 h. The slurry produced by the hydrothermal reaction was then filtered and washed with deionized water for three times. The filter cake obtained by washing was mixed with 300 ml of deionized water and 31.56 g of Co(OH) ₂ (equivalent to 20 g in terms of Co) and slurried. The slurry was dried and formed in a spray dryer. The obtained granular powder was calcined at 450° C. for 4 hours to obtain a carrier marked as Z-4.

(2) Preparation of catalyst:

A catalyst was prepared according to the method of Example 1, namely, the catalyst C4 of the present invention was obtained.

Embodiment 5:

(1) Preparation of carrier:

Prepare carrier Z-5 (same as carrier Z-1) according to the method of Example 1;

(2) Preparation of catalyst:

The catalyst was prepared according to the method of Example 1, except that “76.78 g of Co(NO ₃ ) ₂ ·6H ₂ O (equivalent to 15.55 g in terms of Co) was dissolved in 300 ml of deionized water, 15.55 g of Ru(NO)(NO ₃ ) ₃ aqueous solution (Ru concentration of 5 wt %) (equivalent to 0.78 g in terms of Ru) and 20.26 g of 50 wt % Mn(NO 3 ) _{2 aqueous solution (equivalent to 3.11 g in terms of Mn) were added, and the mixture was mixed well to use as the impregnation solution” was replaced by “65.72 g of Co(CH 3 COO) 2 ·4H 2 O (equivalent to 15.55 g in terms of Co), 1.54 g of Pt(NH 3 ) 4} (NO ₃ ) 2 (equivalent to 0.78 g in terms of Pt) and 13.87 g of Mn(CH ₃ COO) _{2 ·4H 2 O” was used to prepare the catalyst according to the method of Example 1, except that “76.78 g of Co(NO 3 ) 2 ·6H 2} O (equivalent to 15.55 g in terms of Co) was dissolved in 300 ml of deionized water, 15.55 g of Ru(NO)(NO ₃ ) ₃ aqueous solution (Ru concentration of 5 wt %) (equivalent to 0.78 g in terms of Ru) and 20.26 g of 50 wt _% Mn(NO ₃ ) ₂ aqueous solution (equivalent to 3.11 g in terms of Mn) were added, and _the mixture was mixed well to use as the impregnation solution _” . O (equivalent to 3.1 g in terms of Mn) was dissolved in 300 ml of deionized water and mixed evenly to form an "impregnation solution", thereby obtaining the catalyst C5 of the present invention.

Embodiment 6:

The catalyst was prepared according to the method of Example 1, except that "weighing 200 g of silicon oxide powder" was replaced by "weighing 150 g of silicon oxide powder and 125 g of silica sol (containing 40 wt % of silicon oxide)" to obtain carrier Z-6 and catalyst C6.

Embodiment 7:

The catalyst was prepared in the same manner as in Example 1, except that no Mn additive was added, to obtain carrier Z-7 (same as carrier Z-1) and catalyst C7.

Embodiment 8:

The catalyst was prepared in the same manner as in Example 1, except that in step (1), "31.56 g of Co(OH) ₂ (equivalent to 20 g in terms of Co)" was replaced with "98.78 g of Co(NO ₃ ) ₂ ·6H ₂ O (equivalent to 20 g in terms of Co)" to obtain carrier Z-8 and catalyst C8.

Example 9

The catalyst was prepared in the same manner as in Example 1, except that

In step (1), the amount of Co(OH) ₂ was changed to be equivalent to 10 g in terms of Co;

In step (2), the amount of Co(NO ₃ ) ₂ ·6H ₂ O used was changed so as to correspond to 19.70 g in terms of Co.

The carrier Z-9 and the catalyst C9 are obtained.

Example 10

The catalyst was prepared in the same manner as in Example 1, except that

In step (1), the amount of Co(OH) ₂ was changed to be equivalent to 30 g in terms of Co;

In step (2), the amount of Co(NO ₃ ) ₂ ·6H ₂ O used was changed so as to correspond to 7.38 g in terms of Co.

The carrier Z-10 and the catalyst C10 were obtained.

Comparative Example 1:

The catalyst was prepared according to the method of Example 2 in CN105772107A to obtain carrier ZD-1 and catalyst D1.

Comparative Example 2:

The catalyst was prepared according to the method of Example 1 in CN102039133A to obtain catalyst D2.

Comparative Example 3:

The catalyst was prepared according to the method of Example 2 in CN101983102A to obtain carrier ZD-3 and catalyst D3.

Comparative Example 4:

The catalyst was prepared in the same manner as in Example 1, except that the process of preparing carrier Z-1 in step (1) was not carried out. Instead, 200 g of silicon oxide powder (the same silicon oxide powder used in preparing the carrier in Example 1) was directly weighed as the carrier, and the amounts of Co(NO ₃ ) ₂ ·6H ₂ O, Ru(NO)(NO ₃ ) ₃ and Mn(NO ₃ ) ₂ in the impregnation solution were adjusted according to the weight ratio in Table 2 to prepare the impregnation solution. The catalyst was prepared in the same manner as in step (2) of Example 1.

Catalyst D4 was obtained.

Comparative Example 5:

The catalyst was prepared according to the method of Example 1, except that there was no hydrothermal treatment step in the preparation of the carrier. Instead, solution B, silica powder, deionized water and Co(OH) ₂ were directly mixed and slurried in the same amounts as in Example 1, the slurry was dried and formed in a spray dryer, and the obtained granular powder was calcined at 450°C for 4 hours to obtain carrier ZD-5 and catalyst D5.

Comparative Example 6:

The catalyst was prepared according to the method of Example 1, except that no Co source was added during the preparation of the carrier, and the active component cobalt was all loaded on the carrier through the impregnation solution. Therefore, "weigh 76.78 g Co(NO ₃ ) ₂ ·6H ₂ O and dissolve it in 300 ml deionized water" in Example 1 was replaced by "weigh 171.76 g Co(NO ₃ ) ₂ ·6H ₂ O and dissolve it in 300 ml deionized water" to obtain carrier ZD-6 and catalyst D6.

Test Case I

The carriers obtained in the above examples and comparative examples were respectively subjected to the following tests.

(1) Specific surface area and average pore size

The specific surface area and pore structure of the carrier were measured using a Micromeritics ASAP 2000 physical adsorption instrument. During the test, the sample was cooled to -196°C in liquid nitrogen and a low-temperature _N2 adsorption-desorption experiment was performed. The specific surface area was then calculated using the BET equation, and the average pore size was calculated according to the BJH method. The results are recorded in Table 1.

(2) Wear resistance

The analysis of the wear resistance of the carrier is completed on a spray cup fluidized wear index tester. Weigh 50g of sample and put it into the spray cup, open the air inlet valve, set the air flow rate to 10L/min, and the air flows into the spray cup after humidification. Smaller particles escape from the outlet of the spray cup and are collected in the filter cartridge. After 5 hours, close the air inlet valve and weigh the mass of fine powder in the filter cartridge (g), recorded as m. The sample wear rate is calculated as follows: Wear rate % = m/50/5×100%, and the results are recorded in Table 1.

(3) Particle size distribution

The particle size and distribution of the carrier powder were measured using a Malvern Mastersizer 3000 laser particle size analyzer. It was found that the particle sizes of the obtained carrier powders were all in the range of 1-500 μm. The proportion of particles with a particle size between 38 and 150 μm in the sample, i.e., the particle size distribution (%), was calculated and recorded in Table 1. The results are recorded in Table 1.

(4) Scanning electron microscopy observation

The carriers prepared in the examples were observed by scanning electron microscopy (SEM), and it was found that the carriers obtained in the examples were all spherical particles of uniform size. The results are recorded in Table 1.

(5) Component analysis

The weight composition analysis was performed using an X-ray fluorescence spectrometer (XRF), model ZSX PrimusII (Rigaku), Upside Radiation X-ray generator, 4kW Rh target, test element category range F-U, test area diameter 30mm, and test method full element semi-quantitative method. The results are recorded in Table 2.

In Table 1, the vectors identical to Z-1 (including Z-5, Z-7, and ZD-5) are not listed, and ZD-2 without a separate vector is not listed.

Table 1

Carrier Specific surface area (m ² /g) Average pore size (nm) Wear rate (%/h) Particle size distribution(%) Z-1 160.3 17.5 2.9 93.1 Z-2 155.8 18.3 2.4 91.3 Z-3 174.6 16.5 3.2 94.8 Z-4 154.6 19.8 2.1 90.6 Z-6 179.5 16.3 2.6 93.9 Z-8 181.3 15.8 2.8 93.5 Z-9 169.8 16.9 3.1 93.4 Z-10 154.1 19.9 2.7 90.2 ZD-1 104.0 20.3 3.3 88.5 ZD-3 193.4 13.8 5.2 81.6 ZD-4 215.7 12.5 3.5 92.3 ZD-5 153.5 18.7 3.0 90.2 ZD-6 209.3 12.9 3.1 93.0

It can be seen from Table 1 that the carriers of the present invention generally have more suitable specific surface area, larger average pore size, lower wear rate and higher particle size distribution, and their comprehensive performance is better than that of the comparative example.

Test Case II

The catalysts obtained in the above examples and comparative examples were tested as follows, and the results are recorded in Table 2.

(1) Component analysis

The weight composition analysis was carried out using an X-ray fluorescence spectrometer (XRF), model ZSX PrimusII (Rigaku), Upside Radiation X-ray generator, 4kW Rh target, the test element category range was F-U, the test area diameter was 30mm, and the test method was a full element semi-quantitative method.

The test was carried out twice. The first time, the carrier was analyzed to obtain the composition of each component in the carrier, where the Co content was recorded as Co1; the second time, the catalyst prepared from the above carrier was analyzed to obtain the composition of each component in the catalyst, where the Co content was recorded as Cototal, and Co2 was calculated as Cototal-Co1, where Co2 is the Co content loaded by impregnation (excluding Co in the carrier). The results are shown in Table 2.

(2) Catalytic performance test of Fischer-Tropsch synthesis reaction

The prepared catalyst needs to be reduced before the reaction. The specific reduction conditions are as follows: 1g of catalyst is loaded into a fixed bed reactor, pure _H2 is introduced at a flow rate of 8L/(g catalyst·h), the temperature is raised to 400°C at a rate of 5°C/min, and the reduction is carried out at normal pressure for 10h. After the reduction is completed, the temperature is lowered to room temperature in a reducing atmosphere.

The reduced catalyst was transferred to a high-pressure reactor containing 300 g of liquid paraffin through a glove box, and the reactor was sealed. In a nitrogen atmosphere, the temperature was increased to 180°C at a heating rate of 1°C/min, and then the reaction raw gas was switched to the reaction temperature at a heating rate of 0.5°C/min.

The reaction conditions of the catalyst are: raw gas composition H ₂ /CO/N ₂ = 16/8/1 (volume ratio), set temperature is 210°C, set pressure is 2MPa, and the flow rate of the reaction mixture is 3L/(g catalyst·h). The reaction products are collected by hot trap and cold trap respectively, and the gas products are discharged after metering. When the catalyst reaches a steady state, the catalyst performance is examined within a reaction time of 10-80h.

The contents of gaseous products such as CO, H ₂ , CH ₄ , CO ₂ , and C ₂ -C ₄ were measured online using Agilent's 7890A gas chromatograph. The CO conversion rate and hydrocarbon selectivity were calculated using the following formula (where C ₅₊ represents hydrocarbons with a carbon number greater than 5):

The conversion rate of CO is calculated by the following formula:

The selectivity of methane (C ₁ ) is calculated by the following formula:

The selectivity of C _2-4 was calculated by the following formula:

The selectivity of C ₅₊ is calculated by the following formula: C ₅₊ selectivity (%) = S _C5+ = 1 - S _CH4 - S _C2-4

(3) Hydrothermal stability

In order to compare the hydrothermal stability of the catalyst under high water partial pressure, the catalyst was subjected to Fischer-Tropsch reaction according to the catalytic performance test method described in Test Example II (2). After 50 hours of reaction, the water vapor valve was opened to introduce water vapor, and the volume ratio of water vapor to raw gas was maintained at 1:10. After 3 hours, the introduction of water vapor was stopped, and the Fischer-Tropsch reaction was continued for 80 hours. The catalysts of Example C1 and Comparative Examples D1-D3 were tested in the same manner as above, and the reaction results are shown in Figure 1. It can be seen from the figure that after 3 hours of water vapor was introduced during the reaction, the activity and stability of each catalyst were significantly reduced. Among them, the CO conversion rate of the C1 catalyst decreased from 64.0% to 54.6%, and the deactivation rate was 16% during the 30-hour reaction after the water vapor treatment; the CO conversion rate of the D1 catalyst decreased from 46.0% to 33.8%, and the deactivation rate was 17% during the 30-hour reaction after the water vapor treatment; the CO conversion rate of the D2 catalyst decreased from 47.9% to 19.4%, and the deactivation rate was 20.7% during the 30-hour reaction after the water vapor treatment; the CO conversion rate of the D3 catalyst decreased from 46.9% to 32.0%, and the deactivation rate was 25.8% during the 30-hour reaction after the water vapor treatment; by comparison, it can be found that after the water vapor treatment, the cobalt-based Fischer-Tropsch synthesis catalyst of the present invention can maintain better activity and stability.

Table 2

As can be seen from Table 2, the cobalt-based catalyst of the present invention has a high CO conversion rate when the reaction is 10 hours, and in a preferred case can reach more than 60%, and the CO conversion rate does not decrease significantly after 80 hours of reaction. The cobalt-based catalyst of the present invention has a low methane selectivity and a high selectivity for C ₅₊ . It can be seen that compared with the comparative example, the cobalt-based catalyst of the present invention can have both a higher CO conversion rate and a C ₅₊ selectivity (lower methane selectivity).

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 (21)

1. A composite oxide material used as a catalyst carrier for Fischer-Tropsch synthesis, characterized in that the composite oxide material contains Si, Zr, Ti and Co; relative to 100 parts by weight of the Si element calculated as _SiO2 , the content of the Zr element calculated as _ZrO2 is 3-8 parts by weight, the content of the Ti element calculated as _TiO2 is 2-40 parts by weight, and the content of the Co element calculated as Co is 5-15 parts by weight; the composite oxide material is spherical, with a particle size of 1-500 μm and a specific surface area of 120-190 ^m2 /g; Wherein, the preparation method of the composite oxide material comprises the following steps: (I1) subjecting a first mixture containing a silicon source, a zirconium source, a titanium source, a precipitant and a first solvent to a hydrothermal reaction, and subjecting a material obtained by the hydrothermal reaction to solid-liquid separation to obtain a first solid; (I2) preparing a second mixture containing the first solid, a second solvent and a cobalt source into a slurry, and drying and calcining the slurry; In step (I1), the conditions of the hydrothermal reaction include: temperature of 120-250° C. and time of 10-30 h. 2. The composite oxide material according to claim 1, wherein, relative to 100 parts by weight of the Si element calculated as _SiO2 , the content of the Zr element calculated as _ZrO2 is 3-8 parts by weight, the content of the Ti element calculated as _TiO2 is 5-25 parts by weight, and the content of the Co element calculated as Co is 5-15 parts by weight. 3. The composite oxide material according to claim 1 or 2, wherein the composite oxide material with a particle size in the range of 38-150 μm accounts for more than 85% of the total weight of the composite oxide material. 4 . The composite oxide material according to claim 1 , wherein the average pore size of the composite oxide material is 10-25 nm. 5. A method for preparing a composite oxide material used as a Fischer-Tropsch synthesis catalyst carrier, characterized in that the method comprises the following steps: (I1) subjecting a first mixture containing a silicon source, a zirconium source, a titanium source, a precipitant and a first solvent to a hydrothermal reaction, and subjecting a material obtained by the hydrothermal reaction to solid-liquid separation to obtain a first solid; (I2) preparing a second mixture containing the first solid, a second solvent and a cobalt source into a slurry, and drying and calcining the slurry; Wherein, relative to 100 parts by weight of the Si source calculated as _SiO2 , the amount of the Zr source calculated as _ZrO2 is 3-8 parts by weight, the amount of the Ti source calculated as _TiO2 is 2-40 parts by weight, and the amount of the Co source calculated as Co is 5-15 parts by weight; In step (I1), the conditions of the hydrothermal reaction include: temperature of 120-250° C. and time of 10-30 h. 6. The method according to claim 5, wherein, relative to 100 parts by weight of the silicon source calculated as _SiO2 , the amount of the Zr source calculated as _ZrO2 is 3-8 parts by weight, the amount of the Ti source calculated as _TiO2 is 5-25 parts by weight, the amount of the Co source calculated as Co is 5-15 parts by weight, and the amount of the precipitant is 5-15 parts by weight. 7. The method according to claim 5 or 6, wherein the silicon source is silicon dioxide in powder and/or sol state. 8. The method according to claim 5 or 6, wherein the titanium source is selected from one or more of titanium tetrachloride, metatitanic acid, titanium oxide, titanium sulfate, tetrabutyl titanate and isopropyl titanate. 9. The method according to claim 5 or 6, wherein the zirconium source is selected from one or more of zirconium oxynitrate, zirconium oxychloride and zirconium nitrate. 10. The method according to claim 5 or 6, wherein the precipitating agent is selected from urea and/or hexamethylenetetramine. 11. The method according to claim 5 or 6, wherein the cobalt source is cobalt hydroxide. 12. The method according to claim 5 or 6, wherein in step (I2), the drying is spray drying. 13. The method according to claim 12, wherein the spray drying conditions include: an inlet temperature of 250-400°C and an outlet temperature of 100-250°C. 14. The method according to claim 5 or 6, wherein the calcination conditions include: a temperature of 400-500°C and a time of 3-6 hours. 15. A composite oxide material prepared by the method according to any one of claims 5 to 14. 16. A cobalt-based catalyst, characterized in that the cobalt-based catalyst comprises a composite oxide material and a main active component and a co-active component supported on the composite oxide material, and the composite oxide material is the composite oxide material according to any one of claims 1-4 and 15. 17 . The cobalt-based catalyst according to claim 16 , wherein the main active component is Co element, and the auxiliary active components include Mn element and precious metal element. 18. The cobalt-based catalyst according to claim 17, wherein the sum of the contents of the main active component calculated as an element and the auxiliary active component calculated as an element is 2-20 parts by weight relative to 100 parts by weight of the Si element calculated as _SiO2 in the composite oxide material. 19. The cobalt-based catalyst according to claim 17, wherein, relative to 100 parts by weight of Si element in terms of _SiO2 in the composite oxide material, the content of the Co element is 2-15 parts by weight, the content of the Mn element is 0.5-5 parts by weight, and the content of the precious metal element is 0.1-2 parts by weight. 20. A method for preparing the cobalt-based catalyst according to any one of claims 16 to 19, characterized in that the method comprises the following steps: (II1) preparing an impregnation solution containing a precursor of a main active ingredient and a precursor of a co-active ingredient; (II2) The composite oxide material according to any one of claims 1 to 4 and 15 is sprayed or impregnated with the impregnation solution, and the obtained solid phase is calcined. 21. Use of the composite oxide material according to any one of claims 1 to 4 and 15 or the cobalt-based catalyst according to any one of claims 16 to 19 in a Fischer-Tropsch synthesis reaction.