Fischer-Tropsch synthesis catalysts, their preparation methods and applications

Abstract

The present invention relates to the field of catalysts, and discloses a Fischer-Tropsch synthesis catalyst and a preparation method and application thereof. The catalyst comprises a heat-resistant inorganic oxide and an active component, wherein the active component comprises cobalt and an auxiliary agent, wherein the auxiliary agent is selected from at least one of group IA metal elements, group IIA elements, group IB elements, group IIB elements, group IIIB elements, group IVB elements, group VB elements, group VIB elements, group VIIB elements and group VIII elements, and based on the total amount of the catalyst, the content of cobalt is 10-40% by weight, and the content of the auxiliary agent is 0.002-17% by weight in terms of oxide; after the catalyst is subjected to re-reduction treatment, the number of active centers of the catalyst is 0.02-0.2 mmol hydrogen / g catalyst, and the re-reduction treatment conditions include: a temperature of 220° C., a time of 2 hours, a re-reduction atmosphere of an atmosphere containing hydrogen and argon with a hydrogen concentration of 10% by volume, and a gas-to-agent volume ratio of 15000; and a particle size of the catalyst of 1-10 mm. The catalyst is applied in the Fischer-Tropsch synthesis process and has a high CO conversion rate and C5+ hydrocarbon selectivity.

Description

Technical Field

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

[0002] FT synthesis refers to the reaction in which synthesis gas (CO+H2) is converted into hydrocarbons over a catalyst. The products include alkanes and olefins, and by-products include CO2 and H2O as well as organic oxygen-containing compounds such as alcohols, aldehydes, acids, ketones and esters. After deep processing, the products can be used to obtain high-quality liquid fuels such as gasoline, diesel and aviation kerosene. The first step of FT synthesis is the chemical adsorption of CO and H2. From the perspective of structural chemistry, transition elements with 3d and 4f bonds and energy levels can mostly be used as active components of FT synthesis catalysts. Research results show that three metal catalysts, Fe, Co and Ru, are suitable as active components of catalysts for synthesizing high molecular weight wax hydrocarbons. Among them, Co has high FT synthesis activity, mild reaction conditions, less water-gas shift reaction, stable performance and longer life, so people have studied Co catalysts more widely.

[0003] For gas-solid-liquid multiphase reaction systems such as Fischer-Tropsch (FT) synthesis carried out in fixed bed reactors, the particle size of the catalyst is generally several mm, so the influence of diffusion control on catalytic activity is difficult to avoid. The prior art shows that, compared with catalysts with uniform distribution of active components, catalysts with non-uniform distribution such as eggshell distribution can significantly improve C5+ selectivity in reactions such as Fischer-Tropsch synthesis and reduce methane selectivity due to small diffusion limitation, and are more suitable for reactions such as Fischer-Tropsch synthesis.

[0004] The metal components of metal hydrogenation catalysts are usually prepared in the form of oxides. Only by reducing the catalyst can it have catalytic activity. The quality of catalyst reduction directly affects the performance of the catalyst. Reasonable selection of catalyst reduction pretreatment conditions can make the catalyst have higher activity in the reaction.

[0005] The catalyst reduction method can adopt an off-site pre-reduction treatment or an on-site reduction treatment technology. The off-site pre-reduction technology can improve the utilization rate of the reducing agent and reduce the amount of reducing agent. The pre-reduced catalyst can be restored to activity by simple reactivation at a lower temperature, which can reduce the start-up time, reduce the start-up cost, shorten the start-up cycle, and ultimately increase the economic benefits of the enterprise. The pre-reduced catalyst can be used after being loaded into the reactor and reactivated at low temperature. It is especially suitable for situations where the reduction temperature is significantly higher than the subsequent reaction temperature. The reactor does not need to undergo special processing due to the reduction reaction. The reaction temperature of the cobalt-based Fischer-Tropsch synthesis catalyst is relatively low, and the reactor loaded with the pre-reduced catalyst does not need to undergo special processing due to the reduction reaction, which can reduce investment. Therefore, the industry is in urgent need of a pre-reduced Fischer-Tropsch synthesis catalyst.

[0006] At the same time, for the same catalyst, different reduction and passivation treatment methods have different effects on the activity and selectivity of the reaction. For different catalysts, in order to achieve better activity and selectivity, different reduction and passivation treatment methods are usually adopted. The pre-reduction passivation method in the prior art takes a long time, and it is necessary to develop a pre-reduction method that is simple to operate, safe and reliable for pre-reduction treatment of the catalyst. Summary of the invention

[0007] The purpose of the present invention is to overcome the problem of long reduction time and high temperature of Fischer-Tropsch synthesis catalyst in the prior art, and to provide a Fischer-Tropsch synthesis catalyst and its preparation method and application. The catalyst provided by the present invention can be restored to a hydrogenation catalyst with a higher number of active centers by reduction at a lower temperature and in a shorter time.

[0008] In order to achieve the above-mentioned object, the first aspect of the present invention provides a Fischer-Tropsch synthesis catalyst, which comprises a heat-resistant inorganic oxide and an active component, wherein the active component comprises cobalt and an additive, wherein the additive is selected from at least one of Group IA metal elements, Group IIA elements, Group IB elements, Group IIB elements, Group IIIB elements, Group IVB elements, Group VB elements, Group VIB elements, Group VIIB elements and Group VIII elements, and based on the total amount of the catalyst, the content of cobalt is 10-40% by weight, and the content of the additive is 0.002-17% by weight, calculated as oxide;

[0009] The number of active centers of the catalyst after the re-reduction treatment is 0.02-0.2 mmol hydrogen / g catalyst, and the re-reduction treatment conditions include: temperature of 220° C., time of 2 hours, re-reduction atmosphere of an atmosphere containing hydrogen and argon with a hydrogen concentration of 10% by volume, and a gas-to-agent volume ratio of 15000;

[0010] The particle size of the Fischer-Tropsch synthesis catalyst is 1-10 mm.

[0011] A second aspect of the present invention provides a method for preparing a Fischer-Tropsch synthesis catalyst, the method comprising the following steps:

[0012] (1) introducing active components onto a heat-resistant inorganic oxide by an impregnation method to obtain an oxidized catalyst; the active components include cobalt and an additive, the additive is selected from at least one of Group IA metal elements, Group IIA elements, Group IB elements, Group IIB elements, Group IIIB elements, Group IVB elements, Group VB elements, Group VIB elements, Group VIIB elements and Group VIII elements, and the particle size of the heat-resistant inorganic oxide is 1-10 mm;

[0013] (2) reducing the oxidized catalyst in a hydrogen-containing atmosphere;

[0014] The reduction comprises: stage 1) heating the temperature to 160-300°C at a heating rate of 60-150°C / hour and keeping the temperature for 0.5-8 hours; stage 2) heating the temperature to 320-520°C at a heating rate of 50-150°C / hour and keeping the temperature for 0.3-8 hours;

[0015] (3) After the temperature of the catalyst obtained by reduction in step (2) drops below 60° C., the catalyst obtained by reduction in step (2) is passivated, wherein the passivation comprises: continuously introducing an oxygen-containing gas below 60° C. and controlling the passivation temperature to be no higher than 80° C.; wherein the oxygen concentration of the oxygen-containing gas is continuously increased.

[0016] The third aspect of the present invention provides the use of the Fischer-Tropsch synthesis catalyst provided in the first aspect or the Fischer-Tropsch synthesis catalyst prepared by the preparation method provided in the second aspect in a Fischer-Tropsch synthesis reaction.

[0017] Through the above technical scheme, the pre-reduction hydrogenation catalyst provided by the present invention has a suitable degree of reduction, has many active centers, good reactivation performance, and good stability. It can restore its activity under lower re-reduction conditions (for example, the re-reduction temperature is 220°C and the time is 2 hours). It has better Fischer-Tropsch synthesis performance when applied to the Fischer-Tropsch synthesis process, especially has a higher CO conversion rate and C5+ hydrocarbon selectivity.

[0018] The pre-reduction type hydrogenation catalyst of the present invention can be restored to a hydrogenation catalyst with a higher number of active centers at a relatively low temperature, thereby reducing the start-up time and the investment in reduction equipment.

[0019] The preparation method provided by the present invention, through the above-mentioned specific reduction process, cooperates with a specific passivation process, and cooperates with each other, so that the metal components in the catalyst can be quickly reduced better and more at a lower temperature and in a shorter time, and cooperates with subsequent moderate passivation to jointly improve the performance of the obtained pre-reduction type hydrogenation catalyst, and the reduction passivation efficiency is high. The obtained pre-reduction type hydrogenation catalyst has many active centers, and can be restored to a hydrogenation catalyst with a higher number of active centers at a lower re-reduction temperature before application. DETAILED DESCRIPTION

[0020] 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.

[0021] In the present invention, the gas-to-catalyst ratio refers to the ratio of the volume of gas passing through the catalyst bed per hour to the volume of the catalyst. In the reduction process (or re-reduction process), the gas in the gas-to-catalyst ratio refers to the reducing gas (i.e., hydrogen-containing gas), and in the passivation process, the gas in the gas-to-catalyst ratio refers to the passivating gas (i.e., oxygen-containing passivating gas, also called oxygen-containing gas).

[0022] In the present invention, for the purpose of distinction, the reduction of the catalyst before passivation is referred to as "reduction", and the reduction of the catalyst after passivation is referred to as "re-reduction".

[0023] The first aspect of the present invention provides a Fischer-Tropsch synthesis catalyst, which comprises a heat-resistant inorganic oxide and an active component, wherein the active component comprises cobalt and an additive, wherein the additive is selected from at least one of Group IA metal elements, Group IIA elements, Group IB elements, Group IIB elements, Group IIIB elements, Group IVB elements, Group VB elements, Group VIB elements, Group VIIB elements and Group VIII elements, and the content of cobalt is 10-40% by weight and the content of the additive is 0.002-17% by weight, based on the total amount of the catalyst and calculated as oxide;

[0024] The number of active centers of the catalyst after the re-reduction treatment is 0.02-0.2 mmol hydrogen / g catalyst, and the re-reduction treatment conditions include: temperature of 220° C., time of 2 hours, re-reduction atmosphere of an atmosphere containing hydrogen and argon with a hydrogen concentration of 10% by volume, and a gas-to-agent volume ratio of 15000;

[0025] The particle size of the Fischer-Tropsch synthesis catalyst is 1-10 mm.

[0026] The particle size of the present invention refers to the maximum straight-line distance between any two different points on the catalyst particle; for example, when the catalyst is a spherical particle, the particle size refers to its diameter.

[0027] The Fischer-Tropsch synthesis catalyst provided by the present invention has more active centers, good reactivation performance, good stability, and can restore activity under relatively low re-reduction conditions (for example, the re-reduction temperature is 220° C., and the time is 2 hours). When applied to the Fischer-Tropsch synthesis process, it has better Fischer-Tropsch synthesis performance, especially higher CO conversion rate and C5+ hydrocarbon selectivity.

[0028] In the present invention, the number of active centers of the catalyst is obtained by performing a H2-programmed temperature desorption (H2-TPD) test on an Autochem2950 fully automatic high-pressure chemical adsorption instrument produced by Micromeritics Corporation of the United States. The test method includes: weighing 0.2000g of a 40-60 mesh sample, first performing a re-reduction activation, and the re-reduction conditions are: H2-Ar mixed gas with a hydrogen content of 10 volume %, a flow rate of 50mL / min, heating to 220°C at a heating rate of 10°C / min for reduction for 2h. The reduced catalyst is cooled in a H2-Ar mixed gas with a hydrogen content of 10 volume %, and after the temperature drops to 55°C, it is switched to Ar gas for purging, with an Ar flow rate of 20mL / min, until the baseline is stable, and then a H2-TPD experiment is performed. The experimental conditions and procedures of H2-TPD were as follows: the carrier gas was Ar, the carrier gas flow rate was 20 mL / min, the heating rate was 10 °C / min, the final temperature was 400 °C, and the thermal conductivity detector (TCD) detected the signal to obtain the TPD curve.

[0029] According to a preferred embodiment of the present invention, based on the total amount of the catalyst, the content of cobalt is 12-35% by weight and the content of the auxiliary agent is 0.002-10% by weight in terms of oxide.

[0030] The present invention has a wide selection range for the auxiliary agent. Preferably, the auxiliary agent is selected from one or more of La, Zr, Mn, V, Cr, Cu, Ce, W, Ti, Zn, Sc, Mg, Ca, Be, Na, K, Ru, Ag, Au, Re, Pt and Pd, and more preferably selected from one or more of La, Zr, Cu, Ce, W, Ti, Ru, Ag, Au, Re, Pt and Pd. In the preferred case of the present invention, the catalyst exhibits better CO conversion rate and C5+ hydrocarbon selectivity in the Fischer-Tropsch synthesis reaction.

[0031] In a preferred embodiment of the present invention, in addition to cobalt and additives, the active components may optionally contain other components, and those skilled in the art may select them according to their needs, as long as they are beneficial to improving the catalytic performance of the catalyst in the Fischer-Tropsch synthesis reaction.

[0032] In the present invention, the heat-resistant inorganic oxide may be an inorganic oxide conventionally used in the art. Preferably, the heat-resistant inorganic oxide is selected from one or more of aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, calcium oxide and titanium oxide, more preferably aluminum oxide and / or silicon oxide.

[0033] According to a preferred embodiment of the present invention, the number of active centers of the catalyst after the re-reduction treatment is 0.025-0.15 mmol hydrogen / g catalyst.

[0034] According to a preferred embodiment of the present invention, the catalyst is characterized by TPR, and in its TPR curve, the temperature corresponding to the peak of the low-temperature reduction peak with the largest area is 150-280°C, preferably 160-270°C. The temperature corresponding to the peak of the low-temperature reduction peak with the largest area in the TPR spectrum curve can be used as an indicator for evaluating the regeneration performance of the passivated catalyst. The lower the temperature corresponding to the peak of the low-temperature reduction peak with the largest area, the easier the catalyst is to regenerate. The Fischer-Tropsch synthesis catalyst provided by the present invention has good regeneration performance.

[0035] In the present invention, the TPR (i.e., programmed temperature reduction) characterization is carried out on an Autochem2950 fully automatic high-pressure chemical adsorption instrument produced by Micromeritics, USA. The specific test conditions include: taking 0.20g of sample, first heating the sample to 120°C for dehydration treatment for 1 hour under 50mL / min Ar gas flow at a heating rate of 10°C / min, and after the temperature drops to 50°C, performing a TPR experiment. The experimental conditions and procedures of TPR are: the reducing gas is 10 volume % H2-Ar mixed gas, the flow rate is 50mL / min, and the temperature is increased to 900°C at a heating rate of 10°C / min; in the above-mentioned heating process, the signal is detected by a thermal conductivity detector (TCD) to obtain a TPR spectrum curve.

[0036] A second aspect of the present invention provides a method for preparing a Fischer-Tropsch synthesis catalyst, the method comprising the following steps:

[0037] (1) introducing active components onto a heat-resistant inorganic oxide by an impregnation method to obtain an oxidized catalyst; the active components include cobalt and an additive, the additive is selected from at least one of Group IA metal elements, Group IIA elements, Group IB elements, Group IIB elements, Group IIIB elements, Group IVB elements, Group VB elements, Group VIB elements, Group VIIB elements and Group VIII elements, and the particle size of the heat-resistant inorganic oxide is 1-10 mm;

[0038] (2) reducing the oxidized catalyst in a hydrogen-containing atmosphere;

[0039] The reduction comprises: stage 1) heating the temperature to 160-300°C at a heating rate of 60-150°C / hour and keeping the temperature for 0.5-8 hours; stage 2) heating the temperature to 320-520°C at a heating rate of 50-150°C / hour and keeping the temperature for 0.3-8 hours;

[0040] (3) After the temperature of the catalyst obtained by reduction in step (2) drops below 60° C., the catalyst obtained by reduction in step (2) is passivated, wherein the passivation comprises: continuously introducing an oxygen-containing gas below 60° C. and controlling the passivation temperature to be no higher than 80° C.; wherein the oxygen concentration of the oxygen-containing gas is continuously increased.

[0041] According to the present invention, there is no specific limitation on the source of the heat-resistant inorganic oxide, and the heat-resistant inorganic oxide can be prepared by conventional methods in the art. In one embodiment, the heat-resistant inorganic oxide is an extruded product, and the preparation method thereof comprises:

[0042] (a) uniformly mixing the precursor powder and the extrusion aid according to a certain ratio, adding the peptizing agent solution and kneading them thoroughly, and mixing them in a kneading machine to obtain a composition;

[0043] (b) extruding the composition on an extruder;

[0044] (c) drying and calcining the extrudate obtained in step (b).

[0045] According to the present invention, the extrusion molding can be carried out using various conventional molding equipment. For example, extrusion molding using a screw extruder, compression molding, ball rolling molding, etc. In order to further improve the average pore diameter and pore volume of the heat-resistant inorganic oxide finally obtained, extrusion molding is preferably used, and extrusion molding using a screw extruder is most preferably used. Further preferably, the extrusion conditions of the screw extruder preferably include: an extrusion temperature of 10-100°C, more preferably 40-90°C; an extrusion pressure of 0.5-5MPa, more preferably 0.8-4MPa.

[0046] In the present invention, there is no particular limitation on the shape of the heat-resistant inorganic oxide precursor obtained by extrusion molding. Generally, the shape of the extrusion molding can be butterfly-shaped, column-shaped, clover-shaped, honeycomb-shaped, Raschig ring-shaped or pineapple ball-shaped, etc., preferably butterfly-shaped or clover-shaped. In the above preferred case, it is beneficial to make the finally obtained heat-resistant inorganic oxide have a significantly increased average pore diameter and pore volume, and have a more concentrated pore diameter distribution.

[0047] Wherein, the precursor is a substance that can be calcined to obtain the heat-resistant inorganic oxide. Preferably, in order to ensure the smooth extrusion molding, step (1) also includes introducing appropriate amounts of water, peptizing agent, and extrusion aid. Preferably, the weight ratio of water to the precursor powder is 0.4-2.5:1, more preferably 0.5-1.8:1, and most preferably 0.55-1.5:1; preferably, the peptizing agent is at least one of nitric acid, hydrochloric acid, acetic acid and citric acid, and most preferably nitric acid. In the mixture containing the carrier precursor powder and water, the content of the extrusion aid can be appropriately selected within the range of the extrusion aid dosage in the conventional extrusion molding process. In order to make the heat-resistant inorganic oxide finally obtained have significantly improved mechanical strength, the content of the peptizing agent is preferably 0.1-6 parts by weight, and more preferably 0.6-4 parts by weight relative to 100 parts by weight of the precursor powder.

[0048] In the present invention, the type of the extrusion aid is not specifically limited, for example, it can be at least one selected from starch and its derivatives, cellulose and its derivatives, ethylene glycol, diethylene glycol, acrylic resin, polyurethane, epoxy resin and polyvinyl alcohol. In a preferred case, the extrusion aid is at least one selected from starch and its derivatives, cellulose and its derivatives, ethylene glycol and diethylene glycol, and more preferably at least one selected from starch and its derivatives and cellulose and its derivatives. The starch derivative can be, for example, at least one selected from oxidized starch, esterified starch, carboxymethyl starch, cationic starch, hydroxyalkyl starch and polystarch; the cellulose derivative can be, for example, cellulose ether, cellulose ester or cellulose ether ester. Specifically, the cellulose ester can be at least one selected from cellulose nitrate, cellulose acetate, cellulose acetate butyrate and cellulose xanthate. The cellulose ether can be at least one selected from methyl cellulose, carboxymethyl cellulose, ethyl cellulose, hydroxyethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose.

[0049] In a most preferred embodiment of the present invention, the mixture containing the carrier precursor powder and water contains both the peptizing agent and the extrusion aid, and the contents of the peptizing agent and the extrusion aid are both within the above ranges. In this preferred embodiment, the catalyst carrier thus obtained has a significantly improved average pore diameter and pore volume.

[0050] In the preparation method of the catalyst carrier provided by the present invention, the drying and calcining can be carried out according to conventional operating methods. The carrier precursor after molding is dried, preferably quickly dried. For example, the drying can be carried out at 80-300°C for 1-12 hours, preferably at 120-260°C for 2-5 hours, and most preferably at 140-260°C for 2-5 hours.

[0051] The oxide of the present invention is calcined at 400-1300°C, preferably 450-1100°C, and more preferably 500-700°C to obtain an oxide having a specific surface area of ​​about 0.1-900 m 2 / g, preferably 10-300m 2 / g, and the pore volume is about 0.01-3.6 ml / g, preferably 0.1-0.9 ml / g.

[0052] In the present invention, there is no particular limitation on the specific implementation of the impregnation method in step (1) of the catalyst preparation method, as long as the active component is introduced into the heat-resistant inorganic oxide. Preferably, it includes preparing an impregnation solution of a compound containing an active metal component, and then impregnating the heat-resistant inorganic oxide with the solution. The impregnation method is a conventional method, for example, it can be an excess liquid impregnation or a pore saturation method impregnation. Among them, by adjusting and controlling the concentration, dosage or oxide dosage of the impregnation solution of the compound containing the active component, a catalyst with a specified content can be prepared, which is easily understood and implemented by those skilled in the art.

[0053] In the present invention, there are more than two types of active components, and the active components can be co-impregnated into the heat-resistant inorganic oxide or impregnated into the heat-resistant inorganic oxide in steps, preferably co-impregnated. The specific operation is well known to those skilled in the art, and the present invention will not be repeated here.

[0054] According to a preferred embodiment of the present invention, the heat-resistant inorganic oxide is impregnated with an impregnation solution containing an active component precursor, and then dried and calcined. Preferably, the drying temperature can be 80°C-200°C, and more preferably 100-150°C. Preferably, the calcination temperature is 200°C-800°C, and preferably 300-600°C. The present invention does not have any restrictions on the drying and calcination time, and conventional drying and calcination time can be used. The calcination device used and its operating conditions are conventional equipment and operating parameters in existing calcination technology, and the present invention has no special restrictions on them.

[0055] The present invention has no particular limitation on the types of the precursor of the active component and the precursor of the auxiliary agent, which can be independently selected from water-soluble compounds corresponding to the active component and the auxiliary agent, such as nitrate, acetate, chloride, etc. For example, the precursor of cobalt can be at least one of cobalt nitrate, cobalt chloride, basic cobalt carbonate and cobalt acetate.

[0056] In the preparation method of the present invention, during the reduction process, the introduction of hydrogen (hydrogen has good thermal conductivity and diffusion properties, and can improve the efficiency of heat and mass transfer) in stage 1) can enable the catalyst to be initially reduced while draining water. On the one hand, it can reduce the adverse effects of water vapor on the reduction; on the other hand, it can avoid the decrease in strength of the oxidized catalyst due to the large amount of water released in a short time during the reduction process. Furthermore, by controlling the overall reduction time, cobalt with a suitable grain size can be obtained, which is conducive to obtaining a larger number of active centers; and with suitable passivation conditions, a catalyst that is easy to regenerate and has a large number of active centers can be obtained. The above multiple measures improve the performance of the obtained catalyst as a whole.

[0057] In the present invention, there is no limitation on the method of cooling the catalyst obtained by reduction in step (2), as long as the catalyst can be cooled to the desired temperature, for example, cooling by heat exchange, cold exchange, water cooling, ammonia cooling, purging, etc. Preferably, the catalyst obtained by reduction in step (2) is passivated after its temperature drops below 50°C.

[0058] In the present invention, it can be understood that the passivation temperature is not higher than 80° C. means that the passivation temperature of the catalyst bed is not higher than 80° C. Preferably, the passivation temperature is controlled to be not higher than 70° C.

[0059] According to a preferred embodiment of the present invention, the amount of heat-resistant inorganic oxide and active component used is such that in the oxidized catalyst, the cobalt content is 10-40% by weight, preferably 12-35% by weight, calculated as oxide, based on the total amount of the oxidized catalyst, and the content of the auxiliary agent is 0.002-17% by weight, preferably 0.002-10% by weight.

[0060] According to a preferred embodiment of the present invention, the auxiliary agent is selected from one or more of La, Zr, Mn, V, Cr, Cu, Ce, W, Ti, Zn, Sc, Mg, Ca, Be, Na, K, Ru, Ag, Au, Re, Pt and Pd, and more preferably selected from one or more of La, Zr, Cu, Ce, W, Ti, Ru, Ag, Au, Re, Pt and Pd.

[0061] According to a preferred embodiment of the present invention, the heat-resistant inorganic oxide is selected from one or more of aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, calcium oxide and titanium oxide, more preferably aluminum oxide and / or silicon oxide.

[0062] According to a preferred embodiment of the present invention, the hydrogen-containing atmosphere contains hydrogen and optionally a protective gas, and the protective gas generally refers to a gas that does not participate in the reduction reaction.

[0063] Preferably, the concentration of hydrogen in the hydrogen-containing atmosphere is not less than 5% by volume, more preferably 5-80% by volume, further preferably 10-80% by volume, for example, it can be any point value among 10, 12, 15, 20, 25, 30, 35, 40, 45, 55, 60, 65, 70, 75, 80% by volume and the range between any point values.

[0064] According to a preferred embodiment of the present invention, the protective gas is selected from at least one of nitrogen, helium, argon and neon, more preferably nitrogen.

[0065] In the present invention, preferably, the hydrogen-containing atmosphere is provided by the following method: firstly introducing a protective gas, and then introducing hydrogen. The gas-to-agent ratio in this scheme is calculated based on the hydrogen-containing atmosphere.

[0066] According to a specific embodiment of the present invention, the method further comprises: before the reduction, first replacing the gas in the reduction system with a protective gas to ensure that the content of O2 in the reduction system is ≤0.5% by volume, and then maintaining the pressure of the reduction system at 0-0.2MPa (gauge pressure); then introducing hydrogen-containing gas to meet the composition of the reduction atmosphere, and then reducing according to the reduction process. This preferred solution can prevent the explosion caused by excessive oxygen mixing with the reduction gas, and ensure the safe operation of the device.

[0067] Further preferably, the method further comprises a heat exchange step: the introduced hydrogen-containing gas or protective gas is first heat exchanged with the reduced gas, and then heated. The reduced tail gas is cooled by heat exchange and preferentially separated into gas and liquid, and the tail gas after water removal can be recycled for the reduction process.

[0068] According to a preferred embodiment of the present invention, the gas-to-agent ratio of reduction is 700-5000; preferably, the gas-to-agent ratio of stage 1) is 1000-4000, and the gas-to-agent ratio of stage 2) is 1500-4500; under the above preferred embodiment, it is more conducive to promoting the reduction process of the catalyst and making the catalyst evenly and moderately reduced.

[0069] According to a preferred embodiment of the present invention, the reduction comprises: stage 1) heating to 170-280°C at a heating rate of 70-120°C / hour and keeping warm for 1-5 hours; stage 2) heating to 320-500°C at a heating rate of 50-150°C / hour and keeping warm for 1-8 hours.

[0070] According to a preferred embodiment of the present invention, the reduction stage 2) includes: stage 2-1) heating to 320-400°C at a heating rate of 50-150°C / hour, and keeping warm for 0.5-6 hours; stage 2-2) heating to 420-490°C at a heating rate of 50-150°C / hour, and keeping warm for 0.3-4 hours. The present invention further adopts a two-stage temperature increase reduction method in the reduction stage 2), on the one hand, the cobalt oxide in the catalyst is relatively fully reduced, the reduction degree of the hydrogenation catalyst is increased to an appropriate range, and by using a higher concentration of hydrogen, the heat conduction and diffusion are accelerated, and the adverse effects of water on the reduction are reduced.

[0071] According to a preferred embodiment of the present invention, the hydrogen concentration of the hydrogen-containing atmosphere introduced in stage 2-1) is not lower than that in stage 2-2). Under this preferred embodiment, the reduction process of the catalyst can be promoted, so that the catalyst is uniformly and moderately reduced.

[0072] According to a preferred embodiment of the present invention, the passivation time is 2-70 hours, preferably 6-60 hours, and more preferably 10-40 hours. The passivation time in the prior art pre-reduction method is generally more than 48 hours.

[0073] In step (3) of the present invention, the “oxygen concentration of the oxygen-containing gas continues to increase” means that the oxygen concentration in the introduced oxygen-containing gas shows an overall upward trend. For example, 1. the oxygen concentration in the introduced oxygen-containing gas continues to increase (that is, the oxygen concentration increases at a certain rate); 2. the oxygen concentration in the introduced oxygen-containing gas may be increased after being introduced stably for a certain period of time. In this case, the oxygen concentration increases in stages. For example, in multiple stages, in one specific embodiment, the oxygen concentration in the latter stage is higher than that in the previous stage. In another specific embodiment, the oxygen concentrations in the first few stages are the same and lower than that in the subsequent stages, thereby showing an overall upward trend.

[0074] The present invention has a wide range of optional degrees of increasing oxygen concentration in the oxygen-containing gas, which can be a regular continuous increase, for example, a 2-fold continuous increase, or an exponential continuous increase; or an irregular continuous increase, for example, the oxygen concentration in the second stage is 1 times that in the first stage, the oxygen concentration in the third stage is 1.2 times that in the second stage, and the oxygen concentration in the fourth stage is 2 times that in the third stage.

[0075] In the present invention, preferably, the oxygen concentration of the oxygen-containing gas is continuously increased in stages. In this case, the present invention has a wide range of optional durations for the various stages, as long as it is beneficial to improving the performance of the obtained catalyst. More preferably, during the passivation process, when the oxygen-containing gas introduced in the previous stage makes the oxygen concentration in the passivation outlet gas equal to the oxygen concentration of the introduced oxygen-containing gas, the oxygen-containing gas is introduced into the next stage.

[0076] According to the present invention, preferably, in the passivation process, the oxygen concentration of the oxygen-containing gas is continuously increased in at least 3 stages. It is understandable that, under the preferred embodiment, the oxygen concentration of the oxygen-containing gas in the first stage is lower than the oxygen concentration of the oxygen-containing gas in the second stage, and the oxygen concentration of the oxygen-containing gas in the second stage is lower than the oxygen concentration of the oxygen-containing gas in the third stage, so it is continuously increased. Further, it is understandable that the relative multiples of the oxygen concentration of the oxygen-containing gas in each adjacent two stages can be independently the same or different, such as the relative multiples of the oxygen concentration of the oxygen-containing gas in the first stage and the second stage are 1.5, and the relative multiples of the oxygen concentration of the oxygen-containing gas in the second stage and the third stage can be 1.5, or 2.

[0077] Further preferably, during the passivation process, the oxygen concentration of the oxygen-containing gas is continuously increased in 3-12 stages, for example, the number of stages can be any point value among 4, 5, 6, 7, 8, 9, 10, 11, and 12, and more preferably, it is continuously increased in 4-9 stages. By adopting the preferred embodiment of the present invention, the catalyst can be passivated more uniformly, so that the catalyst has more reduction active centers after re-reduction activation.

[0078] According to a preferred embodiment of the present invention, the passivation gas-to-agent ratio is 200-5000, for example, any point value among 300, 400, 500, 1000, 1200, 1500, 2000, 3000, 4000, 5000 and any point value and range therebetween, more preferably 500-3000.

[0079] According to a preferred embodiment of the present invention, during the passivation process, the gas-to-agent ratio in the first stage is not lower than that in the second stage. This preferred solution is more conducive to promoting a uniform passivation process of the catalyst and improving the passivation efficiency.

[0080] In the present invention, the oxygen-containing gas is preferably a mixture of a protective gas and oxygen, and the protective gas is selected from one or more of helium, argon, carbon dioxide and nitrogen.

[0081] According to a preferred embodiment of the present invention, the method further comprises: before the passivation, firstly introducing a protective gas (preferably carbon dioxide and N2 in a volume ratio of 10-20:1), and then introducing oxygen, so that the oxygen content in the passivation atmosphere meets the required oxygen concentration, and then performing the passivation. The gas after passivation is recycled or directly discharged.

[0082] According to the present invention, when the reduction and passivation are carried out using the same equipment, it is preferred that a protective gas is introduced after the reduction to replace the hydrogen in the system before the passivation is carried out.

[0083] According to a preferred embodiment of the present invention, the passivation temperature is ensured to be no higher than 80° C. by adjusting the pumping amount of protective gas (preferably carbon dioxide).

[0084] According to a preferred embodiment of the present invention, the concentration of the oxygen-containing gas is 0.01-21 volume %.

[0085] According to a preferred embodiment of the present invention, during the passivation process, the initial oxygen concentration of the oxygen-containing gas introduced is 0.01-1% by volume, more preferably 0.01-0.1% by volume.

[0086] According to a preferred embodiment of the present invention, during the passivation process, the oxygen concentration of the oxygen-containing gas introduced in the latter stage is 1-3 times the oxygen concentration of the oxygen-containing gas introduced in the previous stage. Under this preferred embodiment, the catalyst can be passivated more uniformly and controllably, so that the obtained catalyst has more reduction active centers after re-reduction treatment, and the passivation efficiency is high.

[0087] According to a preferred embodiment of the present invention, during the passivation process, the concentration of the oxygen-containing gas introduced in the last stage is 21% by volume, that is, air is introduced.

[0088] In the present invention, the hydrogen-containing gas and the oxygen-containing gas may be used once or recycled; preferably, the gas is recycled.

[0089] In the present invention, there is no restriction on the equipment used for the reduction, for example, the main equipment for reduction can be a reduction furnace or a reduction reactor, the reduction equipment can be a converter, a moving bed reactor, a fixed bed reactor, and the equipment shape can be a cylindrical, a biconical, a spherical device, etc., or an axial reactor or a radial reactor. Preferably, a fixed bed reactor (for example, a flat cylindrical axial reactor with a height-to-diameter ratio of 0.3-0.8) is used, in order to reduce the stay of water vapor in the catalyst bed as much as possible, uniformly reduce the catalysts at different bed positions, and do not damage the mechanical strength of the catalyst. The present invention has no restriction on the equipment used for the passivation, for example, the main equipment for passivation can be a passivation furnace. The present invention can also be equipped with a heat exchanger, a cold exchanger, a water cooler, an ammonia cooler, a dryer, a regeneration heating furnace, and a circulating fan. The reduction equipment and the passivation equipment can be configured separately, or one can be shared, preferably shared, and other supporting equipment is preferably shared.

[0090] According to the present invention, preferably, the reduction degree of the Fischer-Tropsch synthesis catalyst is 47-97% as characterized by TPR. The Fischer-Tropsch synthesis catalyst provided by the present invention has a suitable reduction degree and higher activity. However, the pre-reduction catalyst of the prior art has a higher reduction degree (close to 100%) and low activity.

[0091] In the present invention, the test method of reduction degree is as follows: The test method of reduction degree is as follows: first test the TPR spectrum curve of the pre-reduced catalyst; then calcine 0.2g of the pre-reduced catalyst in an air atmosphere at 450°C for 2h to obtain an oxidized catalyst, test the TPR spectrum curve of the oxidized catalyst according to the TPR test method described in the first aspect, and calculate the reduction degree of the pre-reduced catalyst. Wherein, reduction degree = (direct reduction TPR peak area of ​​oxidized catalyst - high temperature unreduced peak area of ​​pre-reduced catalyst) / direct reduction TPR peak area of ​​oxidized catalyst × 100%.

[0092] The Fischer-Tropsch synthesis catalyst provided by the present invention can be reactivated by hydrogen at a temperature below 300°C.

[0093] The Fischer-Tropsch synthesis catalyst provided by the present invention comprises a heat-resistant inorganic oxide, so that in the reduction and passivation process, the diffusion distance is short, the macroscopic surface area is large, better reduction and passivation can be performed, and the efficiency is high, and the Fischer-Tropsch synthesis performance is better. In addition, the preparation method of the present invention has low cost and can be applied in large-scale industry.

[0094] The third aspect of the present invention provides use of the Fischer-Tropsch synthesis catalyst described in the first aspect or the Fischer-Tropsch synthesis catalyst prepared by the preparation method described in the second aspect in a Fischer-Tropsch synthesis reaction.

[0095] The present invention will be described in detail below through examples.

[0096] Example 1

[0097] An oxidized catalyst having a CoO content of 20 wt % and a ZrO2 content of 1 wt % and a particle size of 1.2-6 mm is selected and placed in a reactor. A nitrogen replacement system is first introduced into the reactor until the oxygen content is qualified (oxygen content ≤ 0.5 volume %), and then hydrogen is supplemented to make the hydrogen content in the hydrogen-nitrogen mixed gas to be 65 volume %, and then a multi-stage reduction process is started. In stage 1), the above-mentioned mixed gas with a gas-to-agent ratio of 1000 is introduced, and the temperature of the catalyst is raised to 200° C. at a heating rate of 80° C. / hour, and the temperature is kept constant for 2 hours; in stage 2), the above-mentioned mixed gas with a gas-to-agent ratio of 2000 is introduced, and in stage 2-1), the temperature of the catalyst is first raised to 400° C. at a heating rate of 70° C. / hour, and the temperature is maintained for 3 hours; then entering stage 2-2), the hydrogen content in the hydrogen-nitrogen mixed gas is adjusted to be 60 volume %, the temperature of the catalyst is raised to 450° C. at a heating rate of 60° C. / hour, and the temperature is maintained for 1 hour, and the reduction step is terminated.

[0098] Then, hydrogen in the nitrogen replacement system is introduced, and the catalyst after the above reduction is cooled to below 45°C, and an oxygen-containing gas with an oxygen concentration of 0.1-21% by volume, which is composed of air and nitrogen, is introduced at normal pressure below 45°C. The oxygen-containing gas with oxygen concentrations of 0.1%, 0.2%, 0.4%, 0.8%, 1.2%, 3.0%, 8.0%, and 21% by volume is introduced in 8 sections in sequence, wherein after the oxygen-containing gas of the previous stage is introduced, when the oxygen concentration at the gas outlet is equal to the oxygen concentration at the gas inlet, the oxygen-containing gas of the latter stage is introduced, and the oxygen concentration is gradually increased for passivation until the passivation ends. The gas-agent ratio of the first two sections of passivation is 1000, and the gas-agent ratio of the latter six sections of passivation is 500. During this period, the passivation temperature of the catalyst bed is controlled to be less than 65°C, and the total passivation time is 12 hours. Obtain a passivated hydrogenation catalyst (i.e., a pre-reduction type low-cobalt content hydrogenation catalyst).

[0099] Comparative Example 1

[0100] The method of Example 1 is different in that the passivation is not segmented, and specifically includes: introducing an oxygen-containing gas with an oxygen concentration of 21% by volume and a temperature below 55°C under normal pressure, with a gas-to-agent ratio of 500, during which the passivation temperature of the catalyst bed is controlled to be less than 170°C, and the passivation time is 4 hours.

[0101] Comparative Example 2

[0102] The method of Example 1 is followed, except that the passivation process is different. Specifically, an oxygen-containing gas with an oxygen concentration of 1.5-21% by volume and a temperature below 55° C. is introduced under normal pressure. The passivation is divided into two stages. The gas-to-agent ratio is 500. The oxygen-containing gas used in the first stage passivation has an oxygen concentration of 1.5% by volume; the oxygen-containing gas used in the second stage passivation has an oxygen concentration of 21% by volume. After the oxygen-containing gas of the first stage is introduced, when the oxygen concentration at the gas outlet is equal to the oxygen concentration at the gas inlet, the oxygen-containing gas of the second stage is introduced. During this period, the passivation temperature of the catalyst bed is controlled to be less than 140° C., and the total passivation time is 5 hours.

[0103] Example 2

[0104] The low-cobalt content oxidized hydrogenation catalyst prepared in Example 1 was selected and placed in a reactor. First, a nitrogen replacement system was introduced into the reactor until the oxygen content was qualified (oxygen content ≤ 0.5 volume %), and then hydrogen was added to the reactor to make the hydrogen content in the hydrogen-nitrogen mixed gas to be 65 volume %, and then a multi-stage reduction process of the catalyst was started. In stage 1), the above-mentioned mixed gas with a gas-to-agent ratio of 1000 was introduced, and the temperature of the catalyst was raised to 200° C. at a heating rate of 80° C. / hour, and the physical water was removed at a constant temperature for 2 hours; in stage 2), the above-mentioned mixed gas with a gas-to-agent ratio of 2500 was introduced, and in stage 2-1), the temperature of the catalyst was raised to 400° C. at a heating rate of 70° C. / hour, and this temperature was maintained for 3 hours; then entering stage 2-2), the hydrogen content in the hydrogen-nitrogen mixed gas was adjusted to 60 volume %, the temperature of the catalyst was raised to 450° C. at a heating rate of 60° C. / hour, and this temperature was maintained for 1 hour, and the reduction step was terminated.

[0105] Then, hydrogen is introduced into the nitrogen replacement system until the hydrogen content is ≤1% by volume, and the catalyst after the reduction is cooled to below 40°C, and an oxygen-containing gas with an oxygen concentration of 0.05-21% by volume composed of air and nitrogen is introduced at normal pressure below 40°C. Oxygen-containing gases with oxygen concentrations of 0.05%, 0.1%, 0.2%, 0.4%, 0.8%, 1.2%, 3.0%, 8.0% and 21% by volume are introduced in 9 sections in sequence, wherein after the oxygen-containing gas of the previous stage is introduced, when the oxygen concentration at the gas outlet is equal to the oxygen concentration at the gas inlet, the oxygen-containing gas of the next stage is introduced, and the oxygen concentration is gradually increased for passivation until the passivation is completed. The gas-agent ratio of the first two sections of passivation is 1000, and the gas-agent ratio of the last seven sections of passivation is 500. During this period, the passivation temperature of the catalyst bed is controlled to be less than 60°C, and the total passivation time is 13 hours. A passivated hydrogenation catalyst (ie, a pre-reduced low-cobalt content hydrogenation catalyst) is obtained.

[0106] Example 3

[0107] The oxidized hydrogenation catalyst prepared in Example 1 was selected and placed in a reactor. First, a nitrogen replacement system was introduced into the reactor until the oxygen content was qualified (oxygen content ≤ 0.5 volume %), and then the hydrogen content in the hydrogen-nitrogen mixed gas was 75 volume % by hydrogen supplementation, and the multi-stage reduction process of the catalyst was started. In stage 1), the above-mentioned mixed gas with a gas-to-agent ratio of 3000 was introduced, and the temperature of the catalyst was raised to 200° C. at a heating rate of 80° C. / hour, and the physical water was removed at a constant temperature for 4 hours; in stage 2), the above-mentioned mixed gas with a gas-to-agent ratio of 2800 was introduced, and in stage 2-1), the temperature of the catalyst was first raised to 400° C. at a heating rate of 60° C. / hour, and this temperature was maintained for 3 hours; then entering stage 2-2), the hydrogen content in the hydrogen-nitrogen mixed gas was adjusted to 70 volume %, the temperature of the catalyst was raised to 450° C. at a heating rate of 50° C. / hour, and this temperature was maintained for 1 hour, and the reduction step was terminated.

[0108] Then, hydrogen is introduced into the nitrogen replacement system until the hydrogen content is ≤1% by volume, and the catalyst after the above reduction is cooled to below 30°C, and an oxygen-containing gas with an oxygen concentration of 0.05-21% by volume composed of air and nitrogen is introduced at normal pressure below 30°C. Oxygen-containing gases with oxygen concentrations of 0.05%, 0.1%, 0.2%, 0.4%, 0.8%, 1.2%, 3.0%, 8.0% and 21% by volume are introduced in 9 sections in sequence, wherein after the oxygen-containing gas of the previous stage is introduced, when the oxygen concentration at the gas outlet is equal to the oxygen concentration at the gas inlet, the oxygen-containing gas of the next stage is introduced, and the oxygen concentration is gradually increased for passivation until the passivation ends. The gas-agent ratio of the first three sections of passivation is 2000, and the gas-agent ratio of the last six sections of passivation is 500. During this period, the passivation temperature of the catalyst bed is controlled to be less than 50°C, and the total passivation time is 11 hours. A passivated hydrogenation catalyst (ie, a pre-reduced low-cobalt content hydrogenation catalyst) is obtained.

[0109] Example 4

[0110] The oxidized hydrogenation catalyst prepared in Example 1 was selected and placed in a reactor. First, a nitrogen replacement system was introduced into the reactor until the oxygen content was qualified (oxygen content ≤ 0.5 volume %), and then the hydrogen content in the hydrogen-nitrogen mixed gas was 75 volume % by hydrogen supplementation, and the multi-stage reduction process of the catalyst was started. In stage 1), the above-mentioned mixed gas with a gas-to-agent ratio of 3000 was introduced, and the temperature of the catalyst was raised to 200° C. at a heating rate of 80° C. / hour, and the physical water was removed at a constant temperature for 2 hours; in stage 2), the above-mentioned mixed gas with a gas-to-agent ratio of 3000 was introduced, and in stage 2-1), the temperature of the catalyst was first raised to 400° C. at a heating rate of 60° C. / hour, and this temperature was maintained for 3 hours; then entering stage 2-2), the hydrogen content in the hydrogen-nitrogen mixed gas was adjusted to 70 volume %, the temperature of the catalyst was raised to 480° C. at a heating rate of 50° C. / hour, and this temperature was maintained for 1 hour, and the reduction step was terminated.

[0111] Then, hydrogen is introduced into the nitrogen replacement system until the hydrogen content is ≤1% by volume, and the catalyst after the above reduction is cooled to below 30°C, and an oxygen-containing gas with an oxygen concentration of 0.05-21% by volume composed of air and nitrogen is introduced at normal pressure below 30°C. Oxygen-containing gases with oxygen concentrations of 0.05%, 0.1%, 0.2%, 0.4%, 0.8%, 1.2%, 3.0%, 8.0% and 21% by volume are introduced in 9 sections in sequence, wherein after the oxygen-containing gas of the previous stage is introduced, when the oxygen concentration at the gas outlet is equal to the oxygen concentration at the gas inlet, the oxygen-containing gas of the next stage is introduced, and the oxygen concentration is gradually increased for passivation until the passivation ends. The gas-agent ratio of the first three sections of passivation is 2000, and the gas-agent ratio of the last six sections of passivation is 500. During this period, the passivation temperature of the catalyst bed is controlled to be less than 50°C, and the total passivation time is 11.5 hours. A passivated hydrogenation catalyst (ie, a pre-reduced low-cobalt content hydrogenation catalyst) is obtained.

[0112] Example 5

[0113] The method of Example 1 was followed, except that the catalyst composition was 25% by weight of CoO, 3% by weight of WO3, and the particle size of the catalyst was 1.6-7 mm, to obtain a Fischer-Tropsch synthesis catalyst CAT5.

[0114] Example 6

[0115] According to the method of Example 1, the difference is that the passivation process specifically includes: cooling the above-mentioned reduced catalyst to below 40°C, and introducing an oxygen-containing gas with an oxygen concentration of 0.05-21% by volume composed of air and nitrogen at below 40°C under normal pressure. Introduce oxygen-containing gases with oxygen concentrations of 0.05%, 0.2%, 0.4%, 0.8%, 1.2%, 3.0%, 8.0%, and 21% by volume in 8 stages, wherein after the oxygen-containing gas of the previous stage is introduced, when the oxygen concentration at the gas outlet is equal to the oxygen concentration at the gas inlet, the oxygen-containing gas of the next stage is introduced, and the oxygen concentration is gradually increased for passivation until the passivation is completed. The gas-to-agent ratio of the first two stages of passivation is 1000, and the gas-to-agent ratio of the last six stages of passivation is 500. During the period, the passivation temperature of the catalyst bed is controlled to be less than 55°C, and the total passivation time is 12 hours. Obtain Fischer-Tropsch synthesis catalyst CAT6.

[0116] Example 7

[0117] According to the method of Example 1, the difference is that the passivation process specifically includes: cooling the reduced catalyst to below 45°C, introducing oxygen-containing gas with an oxygen concentration of 0.15-21% by volume under normal pressure, and sequentially introducing oxygen-containing gas with oxygen concentrations of 0.15%, 0.3%, 1.0%, 6%, 12% and 21.0% by volume in 6 stages; the gas-to-agent ratio in the first 2 stages of passivation is 2000, and the gas-to-agent ratio in the last 4 stages of passivation is 1000, during which the passivation temperature of the catalyst bed is controlled to be less than 55°C, and the total passivation time is 12 hours. The Fischer-Tropsch synthesis catalyst CAT7 is obtained.

[0118] The number of active centers of the catalysts in Examples 1-7 and Comparative Examples 1-2 after re-reduction treatment, the temperature corresponding to the peak value of the low-temperature reduction peak with the largest area in the TPR spectrum curve, and the degree of reduction are listed in Table 1. The re-reduction treatment conditions include: a temperature of 220° C., a time of 2 hours, a re-reduction atmosphere of an atmosphere containing hydrogen and argon with a hydrogen concentration of 10% by volume, and a gas-to-agent volume ratio of 15,000.

[0119] Table 1

[0120]

[0121] It can be seen from Table 1 that the Fischer-Tropsch synthesis catalyst obtained by the method of the present invention has a higher number of active centers, and the temperature corresponding to the peak value of the low-temperature reduction peak with the largest area is lower, and the catalyst is easier to regenerate.

[0122] Test Case

[0123] The pre-reduction catalysts obtained in the above examples and comparative examples were evaluated in a fixed-bed Fischer-Tropsch synthesis reactor, with a catalyst dosage of 5 g and a mesh size of 40-60 meshes.

[0124] Before using the catalyst, it is necessary to reduce the catalyst. The reduction gas is hydrogen, and the reduction reaction conditions are: pressure is normal pressure, heating rate is 5℃ / min, hydrogen space velocity is 600h -1 The re-reduction temperature is 220°C and the re-reduction time is 2 hours.

[0125] After re-reduction, the reaction performance test was carried out. The specific reaction conditions were: the raw gas was synthesis gas, wherein the H2 / CO molar ratio was 2 / 1, the pressure was 2.5 MPa, the temperature was 210°C, and the raw gas volume space velocity was 4000 h -1 After the reaction was carried out for 12 hours, a gas sample was taken for chromatographic analysis.

[0126] The reaction performance indicators include: CO conversion rate, methane selectivity, C5+ hydrocarbon selectivity and CO2 selectivity. The reaction performance test results are shown in Table 2.

[0127] The calculation formula of methane selectivity is:

[0128]

[0129] Among them, n CH4 is the number of moles of CO converted to methane, n con is the total molar number of CO converted.

[0130] The formula for calculating the selectivity of C5+ hydrocarbons is: (total moles of CO converted - moles of carbon monoxide converted to carbon dioxide and C1-C4 hydrocarbons) / total moles of CO converted.

[0131] The formula for calculating CO2 selectivity is: moles of C converted to CO2 / total moles of CO converted.

[0132] Table 2

[0133]

[0134] The test results in Table 2 show that the catalyst provided by the present invention has better FT synthesis performance, i.e., higher CO conversion rate and C5+ hydrocarbon selectivity, lower methane selectivity and CO2 selectivity. Moreover, the methane selectivity of the catalyst of the present invention does not increase significantly due to the increase in temperature, which significantly solves the diffusion problem of the FT synthesis reaction.

[0135] 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 Fischer-Tropsch synthesis catalyst, comprising a heat-resistant inorganic oxide and an active component, wherein the active component comprises cobalt and an additive, wherein the additive is selected from at least one of Group IA metal elements, Group IIA elements, Group IB elements, Group IIB elements, Group IIIB elements, Group IVB elements, Group VB elements, Group VIB elements, Group VIIB elements and Group VIII elements, wherein the content of cobalt is 10-40% by weight and the content of the additive is 0.002-17% by weight, based on the total amount of the catalyst and calculated as oxide; After the catalyst is subjected to the re-reduction treatment, the number of active centers of the catalyst is 0.1-0.2 mmol hydrogen / g catalyst, and the re-reduction treatment conditions include: The temperature is 220°C, the time is 2 hours, and the reducing atmosphere is an atmosphere containing hydrogen and argon with a hydrogen concentration of 10% by volume and a gas-to-agent volume ratio of 15000; The particle size of the Fischer-Tropsch synthesis catalyst is 1-10 mm; A method for preparing a Fischer-Tropsch synthesis catalyst, the method comprising the following steps: (1) introducing active components onto a heat-resistant inorganic oxide by an impregnation method to obtain an oxidized catalyst; the active components include cobalt and an additive, the additive is selected from at least one of Group IA metal elements, Group IIA elements, Group IB elements, Group IIB elements, Group IIIB elements, Group IVB elements, Group VB elements, Group VIB elements, Group VIIB elements and Group VIII elements, and the particle size of the heat-resistant inorganic oxide is 1-10 mm; (2) reducing the oxidized catalyst in a hydrogen-containing atmosphere; The reduction comprises: stage 1) heating the temperature to 160-300°C at a heating rate of 60-150°C / hour and keeping the temperature for 0.5-8 hours; stage 2) heating the temperature to 320-520°C at a heating rate of 50-150°C / hour and keeping the temperature for 0.3-8 hours; (3) After the temperature of the catalyst obtained by the reduction in step (2) drops below 60° C., the catalyst obtained by the reduction in step (2) is passivated, wherein the passivation comprises: continuously introducing an oxygen-containing gas below 60° C. and controlling the passivation temperature to be no higher than 80° C.; wherein during the passivation process, the oxygen concentration of the oxygen-containing gas is continuously increased in at least three stages.

2. The Fischer-Tropsch synthesis catalyst according to claim 1, wherein Based on the total amount of the catalyst, the content of cobalt is 12-35% by weight, and the content of the auxiliary agent is 0.002-10% by weight, calculated as oxide.

3. The Fischer-Tropsch synthesis catalyst according to claim 1 or 2, wherein The auxiliary agent is selected from one or more of La, Zr, Mn, V, Cr, Cu, Ce, W, Ti, Zn, Sc, Mg, Ca, Be, Na, K, Ru, Ag, Au, Re, Pt and Pd.

4. The Fischer-Tropsch synthesis catalyst according to claim 3, wherein The auxiliary agent is selected from one or more of La, Zr, Cu, Ce, W, Ti, Ru, Ag, Au, Re, Pt and Pd.

5. The Fischer-Tropsch synthesis catalyst according to claim 1 or 2, wherein The heat-resistant inorganic oxide is selected from one or more of aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, calcium oxide and titanium oxide.

6. The Fischer-Tropsch synthesis catalyst according to claim 5, wherein The heat-resistant inorganic oxide is aluminum oxide and / or silicon oxide.

7. The Fischer-Tropsch synthesis catalyst according to claim 1 or 2, wherein After the catalyst is subjected to re-reduction treatment, the number of active centers of the catalyst is 0.1-0.15 mmol hydrogen / g catalyst.

8. The Fischer-Tropsch synthesis catalyst according to claim 1 or 2, wherein The catalyst is characterized by TPR. In its TPR curve, the temperature corresponding to the peak of the low-temperature reduction peak with the largest area is 150-280°C.

9. The Fischer-Tropsch synthesis catalyst according to claim 8, wherein The catalyst is characterized by TPR. In its TPR curve, the temperature corresponding to the peak of the low-temperature reduction peak with the largest area is 160-270°C.

10. A method for preparing a Fischer-Tropsch synthesis catalyst according to any one of claims 1 to 9, comprising the following steps: (1) introducing active components onto a heat-resistant inorganic oxide by an impregnation method to obtain an oxidized catalyst; the active components include cobalt and an additive, the additive is selected from at least one of Group IA metal elements, Group IIA elements, Group IB elements, Group IIB elements, Group IIIB elements, Group IVB elements, Group VB elements, Group VIB elements, Group VIIB elements and Group VIII elements, and the particle size of the heat-resistant inorganic oxide is 1-10 mm; (2) reducing the oxidized catalyst in a hydrogen-containing atmosphere; The reduction comprises: stage 1) heating the temperature to 160-300°C at a heating rate of 60-150°C / hour and keeping the temperature for 0.5-8 hours; stage 2) heating the temperature to 320-520°C at a heating rate of 50-150°C / hour and keeping the temperature for 0.3-8 hours; (3) After the temperature of the catalyst obtained by the reduction in step (2) drops below 60° C., the catalyst obtained by the reduction in step (2) is passivated, wherein the passivation comprises: continuously introducing an oxygen-containing gas below 60° C. and controlling the passivation temperature to be no higher than 80° C.; wherein during the passivation process, the oxygen concentration of the oxygen-containing gas is continuously increased in at least three stages.

11. The preparation method according to claim 10, wherein: The hydrogen-containing atmosphere contains hydrogen and optionally a protective gas.

12. The preparation method according to claim 11, wherein In the hydrogen-containing atmosphere, the concentration of hydrogen is not less than 5 volume %.

13. The preparation method according to claim 12, wherein: In the hydrogen-containing atmosphere, the concentration of hydrogen is 5-80% by volume.

14. The preparation method according to claim 11, wherein: The protective gas is selected from at least one of nitrogen, helium, argon and neon.

15. The preparation method according to any one of claims 10 to 14, wherein: The gas-to-agent ratio for reduction is 700-5000.

16. The preparation method according to claim 15, wherein: The gas-to-agent ratio in stage 1) is 1000-4000, and the gas-to-agent ratio in stage 2) is 1500-4500.

17. The preparation method according to any one of claims 10 to 14, wherein: The reduction comprises: stage 1) heating the temperature to 170-280°C at a heating rate of 70-120°C / hour and keeping the temperature for 1-5 hours; stage 2) heating the temperature to 320-500°C at a heating rate of 50-150°C / hour and keeping the temperature for 1-8 hours.

18. The preparation method according to any one of claims 10 to 14, wherein: The reduction stage 2) includes: stage 2-1) heating to 320-400°C at a heating rate of 50-150°C / hour and keeping warm for 0.5-6 hours; stage 2-2) heating to 420-490°C at a heating rate of 50-150°C / hour and keeping warm for 0.3-4 hours.

19. The preparation method according to claim 18, wherein: The hydrogen concentration of the hydrogen-containing atmosphere introduced in stage 2-1) is not lower than that in stage 2-2).

20. The preparation method according to any one of claims 10 to 14, wherein: The passivation time is 2-70 hours.

21. The preparation method according to claim 20, wherein: The passivation time is 6-60 hours.

22. The preparation method according to any one of claims 10 to 14, wherein: During the passivation process, the concentration of the oxygen-containing gas is continuously increased in 3-12 stages.

23. The preparation method according to claim 22, wherein: During the passivation process, the concentration of the oxygen-containing gas increases continuously in 4-9 stages.

24. The preparation method according to any one of claims 10 to 14, wherein: The passivation gas-to-agent ratio is 200-5000.

25. The preparation method according to claim 24, wherein: The gas-to-agent ratio of the passivation is 500-3000.

26. The preparation method according to any one of claims 10 to 14, wherein: During the passivation process, the gas-to-agent ratio in the first stage is not lower than the gas-to-agent ratio in the second stage.

27. The preparation method according to any one of claims 10 to 14, wherein: The concentration of the oxygen-containing gas is 0.01-21 volume %.

28. The preparation method according to claim 27, wherein During the passivation process, the initial oxygen concentration of the oxygen-containing gas introduced is 0.01-1% by volume.

29. The preparation method according to claim 28, wherein During the passivation process, the initial oxygen concentration of the oxygen-containing gas introduced is 0.01-0.1 volume %.

30. The preparation method according to any one of claims 10 to 14, wherein: During the passivation process, the oxygen concentration of the oxygen-containing gas introduced in the latter stage is 1-3 times the oxygen concentration of the oxygen-containing gas introduced in the former stage.

31. Use of the Fischer-Tropsch synthesis catalyst according to any one of claims 1 to 9 in a Fischer-Tropsch synthesis reaction.

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