Cobalt-based Fischer-Tropsch synthesis catalyst with excellent carbon deposition resistance and preparation method and application thereof

Abstract

The invention belongs to the technical field of Fischer-Tropsch synthesis catalysts, and particularly relates to a cobalt-based Fischer-Tropsch synthesis catalyst with excellent carbon deposition resistance and a preparation method and application thereof.The preparation method comprises the steps that a Ti precursor, a Zr precursor and an alkaline precipitator are subjected to a precipitation reaction, aging is conducted, a Ti-Zr hydroxide precipitate is generated, filtering and washing are conducted, and the cobalt-based Fischer-Tropsch synthesis catalyst is obtained. A Ti-Zr precipitation filter cake is obtained; the preparation method comprises the following steps: carrying out precipitation reaction on a precursor of Co, a precursor of Mn and an alkaline precipitator, aging to generate a hydroxide precipitate of Co-Mn, and filtering and washing to obtain a precipitate filter cake of Co-Mn; and uniformly mixing the obtained precipitate filter cake, performing extrusion molding, and drying and roasting the molded material to obtain the cobalt-based Fischer-Tropsch synthesis catalyst. The obtained catalyst has excellent carbon deposition resistance, is stable in operation in a synthesis gas raw material with a low hydrogen-carbon ratio, and can be used for synthesizing solid wax with high selectivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of Fischer-Tropsch synthesis catalysts, and in particular relates to a cobalt-based Fischer-Tropsch synthesis catalyst with excellent carbon deposition resistance, and a preparation method and application thereof. Background Art

[0002] The Fischer-Tropsch synthesis reaction is a process in which synthesis gas is converted into hydrocarbons under the catalytic action of a catalyst. The reaction equation is as follows:

[0003] nCO+(2n+1)H2→C n H 2n+2 +nH2OΔH=-165KJ / mol.

[0004] Fischer-Tropsch synthesis is the core of coal-to-liquids and natural gas-to-liquids technology. The performance of Fischer-Tropsch synthesis catalysts directly determines the economy and competitiveness of the entire coal-to-liquids and natural gas-to-liquids technology. Commonly used Fischer-Tropsch synthesis catalysts mainly include iron-based Fischer-Tropsch synthesis catalysts and cobalt-based Fischer-Tropsch synthesis catalysts.

[0005] Compared with iron-based catalysts, cobalt-based catalysts have the significant advantages of high Fischer-Tropsch synthesis activity and low CO2 selectivity, and therefore have received more widespread attention and application worldwide.

[0006] Industrial cobalt-based Fischer-Tropsch synthesis catalysts, whose active component cobalt is usually supported on carriers such as Al2O3, SiO2, TiO2, and ZrO2. In the Fischer-Tropsch synthesis reaction using cobalt-based catalysts, the added value of wax products with longer chain lengths in the hydrocarbon products (especially high-melting wax products with a melting point greater than 100°C) is high, while the added value of gaseous hydrocarbons (such as methane, ethane, and liquid light hydrocarbons such as naphtha) is low. The hydrogen-to-carbon ratio (the molar ratio of H2 to CO) in the feed gas of the Fischer-Tropsch synthesis reaction has the most significant effect on the wax yield. A lower hydrogen-to-carbon ratio can significantly increase the yield of wax products while reducing the yield of gaseous hydrocarbons and liquid light hydrocarbons. However, at a low hydrogen-to-carbon ratio, higher requirements are placed on the catalyst's ability to resist carbon deposition. Conventional cobalt-based catalysts will quickly deactivate at a low hydrogen-to-carbon ratio. Attempts have also been made to modify it in this field.

[0007] Scientific and technological literature (Ind. Eng. Chem. Res. 2010, 49, 11098-11100) points out that compared with Co / Al2O3, post-impregnation additive B can reduce carbon deposition during the reaction process, thereby improving catalyst stability. After running for 200 hours at a temperature of 240°C, a pressure of 2.0 MPa, and a H2 / CO ratio of 2, the activity of the Co / γ-Al2O3 catalyst decreased to 70% of the initial value, while the activity of the 0.5% B-Co / γ-Al2O3 catalyst only decreased to 92% of the initial value.

[0008] Scientific literature (Studies in Surface Ence and Catalysis, 1994, 81: 433-442) points out that adding the additive Ru to Co / SiO2 and Co / TiO2 catalysts can inhibit carbon deposition and delay catalyst deactivation.

[0009] The scientific literature (Catalysis Communications, 2011, 12(6): 539-543) pointed out that after adding Pt as a promoter to Co / Al2O3 catalyst, the presence of high molecular weight carbon on the catalyst was less. The deactivation rate was slower under the reaction conditions of temperature of 230°C, pressure of 2MPa, space velocity of 2000mL / (g·h), and hydrogen-carbon ratio of 2.

[0010] The selectivity and catalytic activity of solid wax (especially high melting point wax) in the industrial production of cobalt-based Fischer-Tropsch synthesis is also a key issue that needs to be overcome in this field. Therefore, the development of cobalt-based catalysts with strong resistance to carbon deposition and tolerance to low hydrogen-carbon ratio is the key to improving the selectivity of solid wax (especially high melting point wax) in the industrial production of cobalt-based Fischer-Tropsch synthesis. Summary of the invention

[0011] The purpose of the present invention is to provide a cobalt-based Fischer-Tropsch synthesis catalyst and a preparation method thereof, in order to address the problems of solid wax selectivity and catalytic activity in the industrial production of cobalt-based Fischer-Tropsch synthesis. The catalyst prepared by a step-by-step co-precipitation process has excellent anti-carbon deposition ability, and the catalyst operates stably under conditions close to industrial conditions and in a synthesis gas feedstock with a relatively low hydrogen-to-carbon ratio, and can synthesize solid wax (especially high-melting point wax with a melting point above 100°C) with high selectivity.

[0012] In order to achieve the above object, the present invention provides the following technical solutions:

[0013] In a first aspect, a method for preparing a cobalt-based Fischer-Tropsch synthesis catalyst is provided, comprising the following steps:

[0014] (1) contacting a Ti precursor and a Zr precursor with an alkaline precipitant-I to perform a precipitation reaction, and performing an aging treatment to generate a Ti-Zr hydroxide precipitate, and then filtering and washing the precipitate to obtain a Ti-Zr precipitation filter cake;

[0015] (2) contacting the Co precursor and the Mn precursor with an alkaline precipitant-II to carry out a precipitation reaction, and then subjecting the mixture to an aging treatment to generate a Co-Mn hydroxide precipitate, and then filtering and washing the precipitate to obtain a Co-Mn precipitate filter cake;

[0016] (3) The Co-Mn precipitate filter cake obtained as above and the Ti-Zr precipitate filter cake obtained as above (for example, mixed in a kneader) are mixed evenly and then extruded into strips. The formed materials are dried and calcined to obtain a cobalt-based Fischer-Tropsch synthesis catalyst.

[0017] According to the preparation method provided by the present invention, in some embodiments, the Ti precursor is selected from one or more of titanium oxychloride, metatitanic acid, titanyl sulfate and titanium dioxide.

[0018] In some embodiments, the Zr precursor is selected from one or more of zirconium oxynitrate, zirconium oxychloride, zirconium dioxide and an organic salt of zirconium.

[0019] In some embodiments, the Mn precursor is selected from one or more of manganese nitrate, manganese acetate and manganese chloride.

[0020] In some embodiments, the Co precursor is selected from one or more of cobalt nitrate, cobalt acetate and cobalt chloride.

[0021] In the present invention, before the precursor of Ti and the precursor of Zr contact with the alkaline precipitant-I, a salt solution of the Ti precursor and a salt solution of the Zr precursor can be prepared first. For example, a solution containing a Ti precursor and a solution containing a Zr precursor can be prepared separately, and then they are mixed to form a mixed solution; or a Ti precursor and a Zr precursor are added to water and mixed to obtain a mixed salt solution containing a Ti precursor and a Zr precursor. The concentration of the mixed salt solution containing a Ti precursor and a Zr precursor can be 0.5-6 mol / L, for example, 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, 4.0 mol / L, 5.0 mol / L.

[0022] In the present invention, before the precursor of Co and the precursor of Mn contact the alkaline precipitant-II, a salt solution of the Co precursor and a salt solution of the Mn precursor can be prepared first. For example, a solution containing a Co precursor and a solution containing a Co precursor can be prepared separately, and then they are mixed to form a mixed solution; or the precursor of Co and the precursor of Co are added to water and mixed to obtain a mixed salt solution containing a Co precursor and a Mn precursor. The concentration of the mixed salt solution containing a Co precursor and a Mn precursor can be 0.5-5 mol / L, for example, 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, 4.0 mol / L, 4.5 mol / L.

[0023] In some embodiments, the alkaline precipitant-I and the alkaline precipitant-II are each independently selected from one or more of ammonia water, sodium bicarbonate and sodium carbonate; the alkaline precipitant-I and the alkaline precipitant-II are the same or different. Before use, the alkaline precipitant-I and the alkaline precipitant-II can be prepared in advance into alkaline precipitant solutions of a certain concentration, and the concentrations of both can be 0.1-5 mol / L, for example, 0.2 mol / L, 0.5 mol / L, 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, 4.0 mol / L, 4.5 mol / L.

[0024] In some embodiments, the alkaline precipitant-I and the alkaline precipitant-II are selected from different species.

[0025] In some embodiments, the alkaline precipitant-I is aqueous ammonia.

[0026] In some embodiments, the alkaline precipitant-II is sodium bicarbonate or sodium carbonate.

[0027] By selecting the types of alkaline precipitant-I and alkaline precipitant-II, the loss of metallic cobalt can be reduced, and problems such as excessively high Na ion concentration in the precipitate and increased washing times can be avoided.

[0028] In some embodiments, in step (1), the molar ratio of the Ti precursor to the Zr precursor is 25 / 1 to 250 / 1; for example, 30 / 1, 40 / 1, 50 / 1, 80 / 1, 100 / 1, 120 / 1, 150 / 1, 180 / 1, 200 / 1, 215 / 1, 220 / 1, 240 / 1, 245 / 1.

[0029] In some embodiments, in step (2), the molar ratio of the Co precursor to the Mn precursor is 10 / 1 to 100 / 1; for example, 12 / 1, 14 / 1, 15 / 1, 18 / 1, 20 / 1, 24 / 1, 25 / 1, 30 / 1, 40 / 1, 50 / 1, 60 / 1, 80 / 1, 90 / 1, 95 / 1.

[0030] In the preparation method of the present invention, when the Co-Mn precipitate filter cake is mixed with the Ti-Zr precipitate filter cake, the Ti-Zr precipitate filter cake and the Co-Mn precipitate filter cake obtained by the precipitation reaction in the previous two steps can be mixed completely. The ratio range of the two precipitates can be calculated based on the content of each component in the catalyst and controlled by the amount of each precursor in steps (1) and (2).

[0031] In some embodiments, in step (1), the process conditions of the precipitation reaction include: the precipitation temperature is room temperature to 70°C (for example, 30°C, 50°C, 60°C); the pH of the precipitation system is 6.0-10.0 (for example, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0); the process conditions of aging include: the temperature is room temperature to 70°C (for example, 30°C, 50°C, 60°C), the pH of the system is 6.0-10.0 (for example, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0), and the aging time is 0.5-12h (for example, 1h, 2h, 4h, 5h, 8h, 10h).

[0032] In some embodiments, in step (2), the process conditions of the precipitation reaction include: the precipitation temperature is room temperature to 70°C (for example, 30°C, 50°C, 60°C); the pH of the system is 6.0-10.0 (for example, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0); the process conditions of aging include: the temperature is room temperature to 70°C (for example, 30°C, 50°C, 60°C), the pH of the system is 6.0-10.0 (for example, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0), and the aging time is 0.5-12h (for example, 1h, 2h, 4h, 5h, 8h, 10h).

[0033] In step (1) and step (2), the process conditions of the precipitation reaction may be the same or different; in step (1) and step (2), the process conditions of the aging may be the same or different. In step (1), the obtained precipitate may be washed until the conductivity of the washing liquid is less than 1000 μs / cm; in step (2), the obtained precipitate may be washed until the conductivity of the washing liquid is less than 1000 μs / cm.

[0034] In some embodiments, in step (3), the mixing process conditions include: at room temperature, the mixing time is 15 min-180 min, for example, 20 min, 30 min, 50 min, 80 min, 120 min, 150 min.

[0035] In some embodiments, in step (3), the process conditions for extrusion molding include: at room temperature, the extrusion molding pressure is 20N-600N, for example, 50N, 100N, 200N, 300N, 400N, 500N, 550N.

[0036] In some embodiments, in step (3), the drying process conditions include: a drying temperature of 100-150°C (e.g., 110°C, 120°C, 130°C, 140°C), and a drying time of 3-12h (e.g., 4h, 5h, 8h, 10h).

[0037] In some embodiments, the calcination process conditions include: the calcination temperature is 350-700°C (e.g., 360°C, 400°C, 450°C, 500°C, 600°C, 650°C), and the calcination time is 2-5h (e.g., 2.5h, 3h, 3.5h, 4h, 4.5h).

[0038] In a second aspect, a cobalt-based Fischer-Tropsch synthesis catalyst having excellent carbon deposition resistance is provided, wherein the cobalt-based Fischer-Tropsch synthesis catalyst uses TiO2 modified by ZrO2 as a carrier;

[0039] The cobalt-based Fischer-Tropsch synthesis catalyst comprises the following components:

[0040] Active ingredient cobalt, 15wt%-50wt% (e.g., 18wt%, 20wt%, 22wt%, 24wt%, 25wt%, 28wt%, 30wt%, 32wt%, 35wt%, 40wt%, 45wt%);

[0041] Additive Mn, 0.2wt%-2wt% (e.g., 0.22wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, 0.5wt%, 0.6wt%, 0.8wt%, 1.0wt%, 1.5wt%, 1.8wt%);

[0042] Support modification aid ZrO2, 0.1wt%-1wt% (e.g., 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.8wt%);

[0043] The remaining component is titanium dioxide;

[0044] Na + The content is less than or equal to 0.1wt% (for example, 0.01wt%, 0.02wt%, 0.04wt%, 0.05wt%, 0.08wt%, 0.09wt%), Cl - The content is less than or equal to 0.3wt% (for example, 0.01wt%, 0.02wt%, 0.04wt%, 0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%).

[0045] According to the cobalt-based Fischer-Tropsch synthesis catalyst provided by the present invention, in some embodiments, the cobalt-based Fischer-Tropsch synthesis catalyst is prepared by the preparation method as described above.

[0046] In some embodiments, the titanium dioxide is composed of anatase titanium dioxide and rutile titanium dioxide, wherein the content of anatase titanium dioxide is greater than that of rutile titanium dioxide.

[0047] In a third aspect, there is provided a cobalt-based Fischer-Tropsch synthesis catalyst prepared by the preparation method as described above or use of the cobalt-based Fischer-Tropsch synthesis catalyst as described above in a Fischer-Tropsch synthesis reaction.

[0048] In the present invention, the Fischer-Tropsch synthesis reaction can be achieved by conventional operations in the art, which will not be described in detail here. After calcination, the cobalt and manganese contained in the catalyst are both present as oxides, and hydrogen is used for activation before performance testing, and most of the cobalt is converted into metallic cobalt, while the manganese still exists as oxides.

[0049] Compared with the prior art, the excellent effects of the present invention are at least as follows:

[0050] 1) The cobalt-based Fischer-Tropsch synthesis catalyst prepared by the present invention has high stability at a low hydrogen-to-carbon ratio when used in the Fischer-Tropsch synthesis reaction, so it can be suitable for operation in a reaction atmosphere with a low hydrogen-to-carbon ratio in industrial applications. The catalyst has a stronger ability to resist fluctuations in the hydrogen-to-carbon ratio of the upstream feed gas during the operation of the industrial device;

[0051] 2) At a low hydrogen-to-carbon ratio, the cobalt-based Fischer-Tropsch synthesis catalyst prepared by the present invention has high wax selectivity, and the selectivity of solid wax can be as high as greater than 70%, while the selectivity for gaseous hydrocarbons (such as methane, ethane, and liquid light hydrocarbons such as naphtha) is low;

[0052] 3) Compared with catalysts supported by other carriers such as alumina, the cobalt-based Fischer-Tropsch synthesis catalyst prepared by the present invention uses a ZrO2-modified TiO2 carrier and controls the amount of the modifier ZrO2. The catalyst supported by the ZrO2-modified TiO2 carrier has the advantages and characteristics of strong anti-carbon deposition ability;

[0053] 4) The present invention adopts a step-by-step co-precipitation preparation process, wherein Co and Mn are co-precipitated by a precipitant, and Zr and Ti are co-precipitated by a precipitant, respectively, and the process conditions for precipitation and aging and the selection of the precipitant are controlled during the step-by-step co-precipitation process, and then the two precipitates are mixed and extruded to obtain a catalyst, which has a significantly better ability to resist carbon deposition than a process in which Co, Mn, Zr and Ti are precipitated in one step; the possible reason is that the interaction between Co and Mn in the catalyst obtained by the step-by-step co-precipitation process of the present invention is stronger, thereby enhancing the ability of the catalyst to resist carbon deposition;

[0054] 5) The inventors of the present application have found through research that in the process of preparing a cobalt-based Fischer-Tropsch synthesis catalyst using the step-by-step coprecipitation preparation process of the present invention, Na ions and Cl ions have a significant inhibitory effect on the catalyst activity, and the lower the Na ion content in the obtained catalyst, the better, while the inhibitory effect produced when the Cl ion content is below 0.3% is relatively small;

[0055] Therefore, the catalyst prepared by the present invention shows excellent anti-carbon deposition ability, the catalyst operates stably in a Fischer-Tropsch synthesis gas feedstock with a lower hydrogen-carbon ratio, and can synthesize solid wax (especially high melting point wax with a melting point above 100° C.) with high selectivity. DETAILED DESCRIPTION

[0056] In order to understand the technical features and content of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the embodiments, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. For those who do not specify specific conditions in the embodiments, they are carried out according to normal conditions or the conditions recommended by the manufacturer.

[0057] <Source of raw materials>

[0058] In the following examples and comparative examples, the sources of some reagents or raw materials used, without specifying the manufacturer, are all conventional products that can be purchased commercially.

[0059] Example 1

[0060] The preparation method of the cobalt-based Fischer-Tropsch synthesis catalyst is as follows:

[0061] (1) Weighing 164 g of titanium tetrachloride and 1.1 g of zirconium oxynitrate (ZrO(NO3)2·2H2O), and dissolving them in 150 g of deionized water to obtain a mixed salt solution containing a titanium precursor and a zirconium precursor;

[0062] Weigh 100 g of deionized water into a large beaker, add the prepared mixed salt solution and 1 mol / L ammonia water in parallel to the large beaker for reaction, adjust the pH value to 8.0 by adding ammonia water, control the temperature to 60°C, and then age for 4 hours under this condition, wash the obtained precipitate with deionized water until the conductivity of the washing liquid is less than 500 μs / cm, and obtain a Ti-Zr precipitate filter cake;

[0063] (2) Weighing 148 g of cobalt nitrate (Co(NO3)2·6H2O) and 6.6 g of a 50% manganese nitrate solution, and dissolving them in 150 g of deionized water to obtain a mixed salt solution containing a cobalt precursor and a manganese precursor;

[0064] Weigh 100 g of deionized water into a large beaker, add the prepared mixed salt solution and a sodium carbonate aqueous solution with a concentration of 1 mol / L into the large beaker in parallel, adjust the pH value to 7.0 by adding the sodium carbonate aqueous solution, control the temperature to 40° C., and then age for 4 hours under this condition, wash the obtained precipitate with deionized water until the conductivity of the washing liquid is less than 400 μs / cm, and obtain a Co-Mn precipitate filter cake;

[0065] (3) The Ti-Zr precipitate filter cake and the Co-Mn precipitate filter cake obtained above were placed in a kneader for kneading. After kneading for 30 minutes, they were extruded into strips at room temperature and an extrusion pressure of 400N. The obtained molded product was then dried at 120°C for 10 hours and then calcined at 500°C for 3 hours to obtain a cobalt-based Fischer-Tropsch synthesis catalyst A1.

[0066] XRF detection results show that the Na ion content in the cobalt-based Fischer-Tropsch synthesis catalyst A1 is 0.04wt%, and the Cl ion content is 0.12wt%.

[0067] Example 2

[0068] The preparation method of the cobalt-based Fischer-Tropsch synthesis catalyst is referred to Example 1, except that in step (1), the obtained precipitate is washed with deionized water until the conductivity of the washing liquid is less than 1000 μs / cm, and in step (2), the obtained precipitate is washed with deionized water until the conductivity of the washing liquid is less than 1000 μs / cm. Finally, the cobalt-based Fischer-Tropsch synthesis catalyst A2 is obtained.

[0069] XRF detection results show that the Na ion content in the cobalt-based Fischer-Tropsch synthesis catalyst A2 is 0.10wt%, and the Cl ion content is 0.23wt%.

[0070] Example 3

[0071] The preparation method of the cobalt-based Fischer-Tropsch synthesis catalyst is similar to that of Example 1, except that in step (2), the amount of manganese nitrate solution added is adjusted to 9.9 g. Finally, the cobalt-based Fischer-Tropsch synthesis catalyst A3 is obtained.

[0072] XRF detection results show that the Na ion content in the cobalt-based Fischer-Tropsch synthesis catalyst A3 is 0.05wt%, and the Cl ion content is 0.11wt%.

[0073] Example 4

[0074] The preparation method of the cobalt-based Fischer-Tropsch synthesis catalyst is similar to that of Example 1, except that in step (2), the amount of cobalt nitrate (Co(NO3)2·6H2O) added is adjusted to 292 g. Finally, the cobalt-based Fischer-Tropsch synthesis catalyst A4 is obtained.

[0075] XRF detection results show that the Na ion content in the cobalt-based Fischer-Tropsch synthesis catalyst A4 is 0.06wt%, and the Cl ion content is 0.10wt%.

[0076] Comparative Example 1

[0077] The preparation method of the cobalt-based Fischer-Tropsch synthesis catalyst is referred to Example 1, except that in step (1), the obtained precipitate is washed with deionized water until the conductivity of the washing liquid is less than 2500 μs / cm, and in step (2), the obtained precipitate is washed with deionized water until the conductivity of the washing liquid is less than 400 μs / cm. Finally, the cobalt-based Fischer-Tropsch synthesis catalyst B1 is obtained.

[0078] XRF detection results show that the Na ion content in the cobalt-based Fischer-Tropsch synthesis catalyst B1 is 0.05wt%, and the Cl ion content is 0.42wt%.

[0079] Comparative Example 2

[0080] The preparation method of the cobalt-based Fischer-Tropsch synthesis catalyst is referred to Example 1, except that in step (1), the obtained precipitate is washed with deionized water until the conductivity of the washing liquid is less than 3000 μs / cm, and in step (2), the obtained precipitate is washed with deionized water until the conductivity of the washing liquid is less than 400 μs / cm. Finally, the cobalt-based Fischer-Tropsch synthesis catalyst B2 is obtained.

[0081] XRF detection results show that the Na ion content in the cobalt-based Fischer-Tropsch synthesis catalyst B2 is 0.54wt%, and the Cl ion content is 0.13wt%.

[0082] Comparative Example 3

[0083] The preparation method of the cobalt-based Fischer-Tropsch synthesis catalyst is as follows:

[0084] (1) Weighing 164 g of titanium tetrachloride, 1.1 g of zirconium oxynitrate (ZrO(NO3)2·2H2O), 148 g of cobalt nitrate (Co(NO3)2·6H2O), and 6.6 g of a 50% manganese nitrate solution, and then dissolving them in 300 g of deionized water to obtain a mixed salt solution containing a titanium precursor, a zirconium precursor, a cobalt precursor, and a manganese precursor;

[0085] Weigh 100 g of deionized water into a large beaker, add the mixed salt solution and a 1 mol / L sodium carbonate aqueous solution into the beaker in parallel, adjust the pH value to 7.0 by adding the sodium carbonate aqueous solution, control the temperature to 40°C, and after aging for 4 hours, wash the obtained precipitate with deionized water until the conductivity of the washing liquid is less than 400 μs / cm to obtain a precipitate filter cake.

[0086] (2) The precipitated filter cake obtained above was placed in a kneading machine for kneading. After kneading for 30 minutes, it was extruded into strips. The obtained molded product was then dried at 120° C. for 10 hours and then calcined at 500° C. for 3 hours to obtain a cobalt-based Fischer-Tropsch synthesis catalyst B3.

[0087] XRF detection results show that the Na ion content of the cobalt-based Fischer-Tropsch synthesis catalyst B3 is 0.05wt%, and the Cl ion content is 0.10wt%.

[0088] The compositions of the catalysts obtained in the examples and comparative examples were measured using XRF, and the results are shown in Table 1.

[0089] The catalytic performance test and evaluation of the catalysts obtained in each embodiment and comparative example are as follows: 0.5 g of the catalyst obtained in each embodiment and comparative example is taken and loaded into a fixed bed reactor, first reduced for 12 hours in a H2 atmosphere, at an air velocity of 2000 ml / g / h, normal pressure, and a temperature of 350°C, and then the reducing gas is switched to a reaction gas to carry out the reaction. The reaction conditions are: raw gas group H2 / CO / N2=50.6 / 46.0 / 3.4, the air velocity is 3200 ml / g / h, the pressure is 2 MPa, and the temperature is 230°C. The CO conversion rate and methane selectivity are measured after 10 hours and 110 hours of reaction, respectively.

[0090] The wax product obtained was collected and cut using a molecular distillation device to cut out the components below the melting point of 110°C. The weight ratio of the components above 110°C to the weight of the wax was calculated, which was the yield of the wax above 110°C.

[0091] Table 1 Catalyst compositions obtained in various embodiments and comparative examples

[0092]

[0093]

[0094] Table 2 Test results of catalyst performance obtained in various embodiments and comparative examples

[0095]

[0096] The components and contents of the catalysts prepared in each embodiment and comparative example are shown in Table 1. The catalyst performance test results in Table 2 show that the catalysts prepared in each embodiment are catalyzed under the condition of low hydrogen-carbon ratio (hydrogen-carbon ratio of 1.1) of the raw gas. The catalysts not only maintain a high CO conversion rate, but also maintain good stability of the CO conversion rate. Under this test condition, the selectivity of the catalyst for 105# high melting point wax is also maintained at more than 50%. The catalysts prepared in Comparative Examples 1-2 are catalyzed under the condition of low hydrogen-carbon ratio (hydrogen-carbon ratio of 1.1) of the raw gas. When too much Na or Cl ions remain in the catalyst, the catalyst activity is significantly reduced; and when the catalyst prepared by the conventional method (Comparative Example 3) is used for catalysis, the deactivation phenomenon of rapid reduction of CO conversion rate occurs.

[0097] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the spirit of the present invention.

Claims

1. A method for preparing a cobalt-based Fischer-Tropsch synthesis catalyst, characterized in that: The steps include: (1) contacting a Ti precursor and a Zr precursor with an alkaline precipitant-I to perform a precipitation reaction, and performing an aging treatment to generate a Ti-Zr hydroxide precipitate, and then filtering and washing the precipitate to obtain a Ti-Zr precipitation filter cake; (2) contacting the Co precursor and the Mn precursor with an alkaline precipitant-II to carry out a precipitation reaction, and then subjecting the mixture to an aging treatment to generate a Co-Mn hydroxide precipitate, and then filtering and washing the precipitate to obtain a Co-Mn precipitate filter cake; (3) The Co-Mn precipitate filter cake obtained as above and the Ti-Zr precipitate filter cake obtained as above are mixed evenly and then extruded into strips. The formed materials are dried and calcined to obtain a cobalt-based Fischer-Tropsch synthesis catalyst.

2. The preparation method according to claim 1, characterized in that: The Ti precursor is selected from one or more of titanium oxychloride, metatitanic acid, titanyl sulfate and titanium dioxide; and / or The Zr precursor is selected from one or more of zirconium oxynitrate, zirconium oxychloride, zirconium dioxide and an organic salt of zirconium; and / or The Mn precursor is selected from one or more of manganese nitrate, manganese acetate and manganese chloride; and / or The Co precursor is selected from one or more of cobalt nitrate, cobalt acetate and cobalt chloride.

3. The preparation method according to claim 1, characterized in that: The alkaline precipitant-I and the alkaline precipitant-II are each independently selected from one or more of ammonia water, sodium bicarbonate and sodium carbonate; the alkaline precipitant-I and the alkaline precipitant-II are the same or different; Preferably, the alkaline precipitant-I is aqueous ammonia; Preferably, the alkaline precipitant-II is sodium carbonate or sodium bicarbonate.

4. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of the Ti precursor to the Zr precursor is 25 / 1 to 250 / 1; In step (2), the molar ratio of the Co precursor to the Mn precursor is 10 / 1 to 100 / 1.

5. The preparation method according to claim 1, characterized in that: In step (1), the process conditions of the precipitation reaction include: the precipitation temperature is room temperature to 70°C; the pH of the system is 6.0-10.0; the process conditions of the aging include: the temperature is room temperature to 70°C, the pH of the system is 6.0-10.0, and the aging time is 0.5-12h; In step (2), the process conditions of the precipitation reaction include: the precipitation temperature is room temperature to 70°C; the pH of the system is 6.0-10.0; the process conditions of the aging include: the temperature is room temperature to 70°C, the pH of the system is 6.0-10.0, and the aging time is 0.5-12h.

6. The preparation method according to claim 1, characterized in that: In step (3), the mixing process conditions include: at room temperature, the mixing time is 15min-180min.

7. The preparation method according to claim 1, characterized in that: In step (3), the process conditions for extrusion molding include: at room temperature, the extrusion molding pressure is 20N-600N.

8. The preparation method according to claim 1, characterized in that: In step (3), the drying process conditions include: drying temperature of 100-150° C., drying time of 3-12 h; and / or The calcination process conditions include: calcination temperature of 350-700° C., and calcination time of 2-5 hours.

9. A cobalt-based Fischer-Tropsch synthesis catalyst having excellent carbon deposition resistance, characterized in that: The cobalt-based Fischer-Tropsch synthesis catalyst uses TiO2 modified by ZrO2 as a carrier; The cobalt-based Fischer-Tropsch synthesis catalyst comprises the following components: Active ingredient cobalt, 15wt%-50wt%; Additive Mn, 0.2wt%-2wt%; Support modification agent ZrO2, 0.1wt%-1wt%; The remaining component is titanium dioxide; Na + Content is less than or equal to 0.1wt%, Cl - Content is less than or equal to 0.3wt%; Preferably, the cobalt-based Fischer-Tropsch synthesis catalyst is prepared by the preparation method as described in any one of claims 1 to 8; Preferably, the titanium dioxide is composed of anatase crystalline titanium dioxide and rutile crystalline titanium dioxide, wherein the content of anatase crystalline titanium dioxide is greater than that of rutile crystalline titanium dioxide.

10. Use of the cobalt-based Fischer-Tropsch synthesis catalyst prepared by the preparation method according to any one of claims 1 to 8 or the cobalt-based Fischer-Tropsch synthesis catalyst according to claim 9 in a Fischer-Tropsch synthesis reaction.

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