Fischer-Tropsch synthesis catalyst, its preparation method and application

Abstract

The present invention relates to the field of Fischer-Tropsch synthesis catalysts, and relates to Fischer-Tropsch synthesis catalysts, their preparation methods and applications. The catalyst comprises: 10-45% by weight of Co, 0.01-2.5% by weight of Mn, 0.01-1.5% by weight of Cl, 0.5-8% by weight of ZrO2, and 35-85% by weight of bulk TiO2; the molar ratio of Cl to Zr is 1:20-1:0.1; the grain size of cobalt tetroxide in the catalyst is 16-27 nm. TiO2 is composed of two crystal forms, anatase and rutile, and the content of the anatase crystal form is greater than that of the rutile crystal form. The prepared catalyst has low methane selectivity, high activity, good anti-sintering and hydrothermal resistance properties, and good stability.

Description

Technical Field

[0001] The present invention relates to the field of Fischer-Tropsch synthesis catalysts, and specifically to Fischer-Tropsch synthesis catalysts, their preparation methods and applications. Background Art

[0002] The Fischer-Tropsch synthesis reaction is a process of converting syngas into hydrocarbons through a catalyst, and its reaction equation is as follows:

[0003] nCO+(2n + 1)H2→C n H2 n +2 + nH2O ΔH=-165 KJ / mol

[0004] Fischer-Tropsch synthesis is the core of coal indirect liquefaction and natural gas to liquids technologies. The performance of Fischer-Tropsch synthesis catalysts directly determines the economy and competitiveness of the entire coal indirect liquefaction and natural gas to liquids technologies. Commonly used Fischer-Tropsch synthesis catalysts are divided into two categories: iron-based and cobalt-based. Compared with iron-based catalysts, cobalt-based catalysts have significant advantages of high Fischer-Tropsch synthesis activity and low CO2 selectivity, and thus have received more extensive attention and applications worldwide.

[0005] In the Fischer-Tropsch synthesis reaction, in addition to hydrocarbons, a large amount of water vapor is generated at the same time. Therefore, in industrial production, especially when using a shell-and-tube fixed-bed reactor, there are relatively stringent requirements for the hydrothermal stability of cobalt-based catalysts.

[0006] In addition, since the Fischer-Tropsch synthesis reaction is a strongly exothermic reaction, the control of the Fischer-Tropsch synthesis reaction heat is crucial for the stable operation of the device in industrial applications. In industrial operation, especially in the initial stage of device operation, the device has not reached a steady state, and the device temperature is prone to fluctuate, which poses a great challenge to the heat resistance of the catalyst.

[0007] To improve the activity and stability of cobalt-based Fischer-Tropsch synthesis catalysts, the active component cobalt is usually supported on carriers such as Al2O3, SiO2, TiO2, ZrO2, etc. However, the γ-Al2O3 carrier has poor hydrothermal stability and will gradually undergo a hydrothermal reaction in a high-hydrothermal atmosphere and then be converted into AlO(OH). Although SiO2 is not easy to chemically react with water vapor, the formed particles are prone to breakage when in contact with water vapor for a long time, which will lead to a rapid decrease in the strength of the catalyst. In addition, the interaction between SiO2 and the active component cobalt is weak. Therefore, when the temperature of the Co / SiO2 catalyst fluctuates greatly, the catalyst is prone to sintering and deactivation.

[0008] The hydrothermal stability of TiO2 is significantly better than that of γ-Al2O3 and SiO2. Therefore, TiO2 is also often used as a carrier for cobalt-based Fischer-Tropsch synthesis catalysts in industry. TiO2 used as a catalyst carrier usually consists of two crystal phases: anatase and rutile.

[0009] CN1230164A discloses a cobalt-based Fischer-Tropsch synthesis catalyst supported on titanium dioxide, in which the ratio of rutile to anatase in the titanium dioxide is less than 2:3 and its surface area is less than 75 m 2 / g. The pore volume of the support measured by mercury porosimetry is at least 0.45 mL / g.

[0010] US6130184A discloses a method for preparing a cobalt-based Fischer-Tropsch synthesis catalyst supported on titanium dioxide. The catalyst is prepared by mixing TiO2 or a titanium raw material with a cobalt source, followed by shaping, and then drying and calcining to obtain the catalyst.

[0011] US20160175821A1 discloses a method for preparing a chlorine-containing cobalt-based Fischer-Tropsch and its use. The catalyst consists of titanium dioxide and at least 5 wt% cobalt, 0.1 - 15 wt% of a promoter, and the promoter includes manganese, rhenium, noble metals of Groups 8 - 10, or a mixture thereof; impregnating the catalyst with a solution containing chloride ions; heating the impregnated catalyst at a temperature of 100 - 500 °C for at least 5 minutes to 2 days. The prepared catalyst contains 0.13 - 10 wt% of elemental chlorine. The solution containing chloride ions is a solution containing one or more metal chloride salts, hydrochloric acid (HCl), one or more organic chlorine compounds, or a combination thereof.

[0012] CN105392558A discloses a method for preparing a chlorine-containing Fischer-Tropsch catalyst, and the method includes the following steps: (a) contacting titanium dioxide with: cobalt and / or a cobalt compound; one or more promoters, where the promoter includes manganese, rhenium, noble metals of Groups 8 - 10, or a mixture thereof; one or more metal chloride salts, hydrochloric acid HCl, one or more organic chlorides, or a combination thereof; and optionally one or more cocatalysts. After treatment at 70 - 350 °C, the catalyst contains at least 5 wt% cobalt, 0.1 - 15 wt% of the promoter, and 0.15 - 3 wt% of elemental chlorine based on the total weight of the catalyst. The patent examples confirm that the addition of Cl improves the selectivity of the catalyst for C5+ hydrocarbons. The inventors found that during the Fischer-Tropsch synthesis reaction, the Cl ions in the catalyst gradually leach out, leading to a decrease in the catalyst performance or even rapid deactivation. Although the above prior art can improve the hydrothermal stability, selectivity for C5+ hydrocarbons, and activity of the catalyst to a certain extent, the stability of the catalyst still needs to be further improved, and the selectivity for gaseous hydrocarbons such as CH4 and C2H6 is still relatively high, while the main target products of the Fischer-Tropsch synthesis reaction are high-value liquid and solid hydrocarbons, and CH4 is a byproduct that needs to be minimized as much as possible.

[0013] Therefore, there is an urgent need for a Fischer-Tropsch synthesis catalyst with a simple synthesis process, good hydrothermal stability, and low selectivity for CH4, C2H6, etc. Summary of the Invention

[0014] The object of the present invention is to overcome the problems existing in the prior art Fischer-Tropsch synthesis catalysts, such as low hydrothermal stability, easy deactivation, cumbersome preparation, high selectivity of gaseous hydrocarbons such as CH4 and C2H6, etc., and to provide a Fischer-Tropsch synthesis catalyst, its preparation method and application.

[0015] The inventors of the present invention have found through research that supported cobalt-based catalysts are prone to deactivation during the Fischer-Tropsch synthesis reaction process. The deactivation mechanisms mainly include sintering of the active phase metal cobalt in the catalyst, carbon deposition on the catalyst surface, phase transformation between the cobalt phase and the support, and sulfur poisoning, etc. The inventors have also found that for TiO2-supported cobalt-based catalysts, carbon deposition and growth of the active phase metal cobalt grains in the catalyst are the main reasons for catalyst deactivation.

[0016] In the present application, the inventors have found that by introducing a Zr promoter into Co / TiO2, the stability of the support TiO2 in the catalyst can be significantly improved. The inventors have found that after the introduction of the Zr promoter and calcination treatment, the Zr promoter mainly exists in the ZrO2 phase. The presence of ZrO2 significantly inhibits the growth of the active phase metal cobalt grains in the catalyst, thereby maintaining the stability of the catalyst.

[0017] The inventors have also found that by introducing a salt solution containing Cl ions, such as cobalt chloride, zirconyl chloride, titanium chloride, titanium oxychloride or / and manganese chloride, etc., during the preparation process of the catalyst, a catalyst with excellent stability can be further obtained. This is mainly because after the addition of Cl, it can inhibit carbon deposition on the catalyst surface and the encapsulation of the metal cobalt by the TiO2 support. This method of introducing Cl ions during the catalyst preparation process has more excellent stability than the catalyst prepared by the post-impregnation method.

[0018] However, since a large amount of water vapor is generated simultaneously during the Fischer-Tropsch reaction process, the inventors have found that Cl ions will gradually be lost as the reaction proceeds, resulting in a decrease in catalyst activity and a deterioration in the selectivity of heavy hydrocarbons. Further introducing a Cl source into the catalyst can further obtain a catalyst with excellent stability. Under the condition that Cl and Zr coexist, Zr can significantly inhibit the loss of Cl ions. The catalyst not only has good stability, but also has low methane selectivity. Therefore, there is a certain synergistic effect between Cl and Zr.

[0019] The inventors have found that when the Cl / Zr is controlled at an appropriate ratio, the stability of the catalyst is extremely excellent. The coexistence of Cl and ZrO2 can not only significantly inhibit the growth of the active phase metal cobalt grains in the catalyst, but also inhibit carbon deposition on the catalyst surface and the encapsulation of the metal cobalt by the TiO2 support, thereby maintaining the activity stability of the catalyst during the reaction process, and the selectivity of the target product C5+ hydrocarbons always remains at a relatively high level.

[0020] In the Fischer-Tropsch synthesis reaction, although some catalysts have good stability in the conversion efficiency of raw material gases CO and H2, with the progress of the reaction, the selectivity of the target liquid and solid hydrocarbons gradually decreases, while the selectivity of the by-product methane gradually increases. When Cl and Zr coexist and are controlled at an appropriate ratio, the stability of the conversion efficiency of CO and H2 and the stability of the target liquid and solid hydrocarbons can be achieved simultaneously.

[0021] To achieve the above object, in a first aspect of the present invention, a Fischer-Tropsch synthesis catalyst is provided, characterized in that, based on the total weight of the catalyst, the Fischer-Tropsch synthesis catalyst comprises: 10-45% by weight of Co, 0.01-2.5% by weight of Mn, 0.01-1.5% by weight of Cl, 0.5-8% by weight of ZrO2, and 35-85% by weight of a carrier TiO2; wherein the molar ratio of Cl to Zr is 1:20 - 1:0.1;

[0022] The grain size of cobalt tetroxide in the catalyst is 16-27 nm.

[0023] In a second aspect of the present invention, a method for preparing the above Fischer-Tropsch synthesis catalyst is provided, comprising the following steps:

[0024] (1) First kneading a Ti source and a Co source to obtain a first mixture;

[0025] (2) Adding a Zr source and an optional peptizing agent to the first mixture for second kneading to obtain a second mixture;

[0026] (3) Adding an Mn source, a Cl source, an optional promoter and an optional Co source to the second mixture for third kneading to obtain a matrix catalyst;

[0027] (4) Drying and calcining the matrix catalyst to obtain a Fischer-Tropsch synthesis catalyst;

[0028] Wherein, the amounts of the Co source, Mn source, Cl source, Zr source, Ti source and promoter are such that, based on the total weight of the catalyst, the content of Co is 10-45% by weight, the content of Mn is 0.01-2.5% by weight, the content of Cl is 0.01-1.5%, the content of ZrO2 is 0.5-8% by weight, the content of titanium dioxide is 35-85% by weight, the content of the promoter is 0-6% by weight, and the molar ratio of Cl to Zr is 1:20 - 1:0.1.

[0029] In a third aspect of the present invention, there is provided the use of the Fischer-Tropsch synthesis catalyst described in the first aspect of the present invention and / or the Fischer-Tropsch synthesis catalyst prepared by the method described in the second aspect of the present invention in the Fischer-Tropsch synthesis reaction.

[0030] The Fischer-Tropsch synthesis catalyst provided by the present invention has high activity, excellent stability, and low methane selectivity, and is particularly suitable for the fixed-bed cobalt-based Fischer-Tropsch synthesis process. In a preferred embodiment, the Fischer-Tropsch synthesis catalyst of the present invention is used in the Fischer-Tropsch synthesis reaction at 215 °C, 2 MPa, and a space velocity of 3 L / (g cat· h), in a syngas with H2 / CO = 2, and the catalyst activity does not deactivate within 500 h when the single-pass CO conversion rate is 75%. At the same time, the selectivity of CH4 of the catalyst is not greater than 6.1%, and even less than 5% after the reaction is stable. Description of the Drawings

[0031] Figure 1 shows the change in CO conversion rate during the Fischer-Tropsch synthesis using the catalyst A1 of the present invention and the prior art catalyst D4 as the reaction time extends. Detailed Embodiments

[0032] In the ranges disclosed herein, the endpoints and any values are not limited to the exact 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, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0033] The first aspect of the present invention provides a Fischer-Tropsch synthesis catalyst, which, based on the total weight of the catalyst, comprises: 10-45% by weight of Co, 0.01-2.5% by weight of Mn, 0.01-1.5% by weight of Cl, 0.5-8% by weight of ZrO2, and 35-85% by weight of TiO2; wherein, the molar ratio of Cl to Zr is 1:20 - 1:0.1;

[0034] The grain size of cobalt tetroxide in the catalyst is 16-27 nm.

[0035] In the catalyst of the present invention, Zr exists in the form of ZrO2, and Co exists in the form of cobalt tetroxide.

[0036] According to the present invention, the titanium dioxide includes anatase-type titanium dioxide and rutile-type titanium dioxide, and the content of anatase-type titanium dioxide in the titanium dioxide is greater than that of rutile-type titanium dioxide.

[0037] Furthermore, based on the total amount of the titanium dioxide, the content of anatase-type titanium dioxide is greater than 50% by weight, more preferably greater than 60% by weight; the content of rutile-type titanium dioxide is less than 40% by weight, preferably less than 30% by weight.

[0038] In this text, the content of anatase titanium dioxide is measured by the XRD method.

[0039] Furthermore, in the catalyst, based on the total weight of the catalyst, the content of Co is 15 - 40% by weight, for example, it can be 16% by weight, 20% by weight, 30% by weight, 35% by weight, and any value within the range composed of any two of the above values; the content of Mn is 0.1 - 1.3% by weight, for example, it can be 0.1% by weight, 0.5% by weight, 1% by weight, 1.3% by weight, and any value within the range composed of any two of the above values; the content of Cl is 0.08 - 1.2% by weight, preferably 0.09 - 1.1% by weight, for example, it can be 0.1% by weight, 0.15% by weight, 0.2% by weight, 0.5% by weight, 1.1% by weight, and any value within the range composed of any two of the above values; the content of ZrO2 is 0.8 - 6.5% by weight, for example, it can be 2% by weight, 3% by weight, 5% by weight, 6.5% by weight, and any value within the range composed of any two of the above values, and the content of titanium dioxide is 45 - 80% by weight, for example, it can be 48% by weight, 55% by weight, 65% by weight, 70% by weight, 75% by weight, 78% by weight, and any value within the range composed of any two of the above values. Among them, the molar ratio of Cl to Zr is 1:15 - 1:0.2.

[0040] Furthermore, the grain size of cobalt tetroxide in the catalyst is 18 - 25 nm.

[0041] In the catalyst of the present invention, Cl can inhibit carbon deposition on the surface of the catalyst. When the content of Cl is less than 0.01% by weight, chloride ions cannot effectively inhibit carbon deposition; when the content of Cl is greater than 1.5% by weight, the activity of the catalyst is inhibited. In particular, when the molar ratio of Cl to Zr is 1:20 - 1:0.1, preferably 1:15 - 1:0.2, the catalytic performance and stability of the catalyst are further improved.

[0042] In the catalyst of the present invention, there is a synergistic effect between Cl and ZrO2 in the catalyst. The co - existence of Cl and ZrO2 can not only significantly inhibit the growth of the active - phase metal cobalt grains in the catalyst, but also inhibit carbon deposition on the surface of the catalyst, maintaining the activity of the catalyst during the reaction process. In addition, the catalyst has a low selectivity for methane.

[0043] Specifically, the catalyst is used in the Fischer-Tropsch synthesis reaction. Before the reaction, the grain size of metallic cobalt in the catalyst is D0; after the catalyst reacts for 20 h, the grain size of metallic cobalt is D1; after the catalyst reacts for 500 h, the grain size of metallic cobalt is D2; (D1 - D0) / D0 ≤ 20%, preferably 0 - 17%; (D2 - D0) / D0 ≤ 35%, preferably 5 - 30%. In this case, the catalytic activity and stability of the catalyst are further improved, and the CO conversion rate of the catalyst can reach more than 53%, and the CH4 selectivity does not exceed 6.1%. Before the catalyst of the present invention is used, it needs to be subjected to a reduction treatment to form a reduced Fischer-Tropsch synthesis catalyst. In the reduced Fischer-Tropsch synthesis catalyst, Zr exists in the form of ZrO2; most of Co exists in the form of metallic Co, and a small amount exists in the form of CoO.

[0044] Preferably, the Fischer-Tropsch synthesis catalyst of the present invention further contains a promoter selected from at least one of platinum, ruthenium, rhodium, palladium, yttrium, rhenium, iron, vanadium, aluminum, and lanthanum.

[0045] In the present invention, the inclusion of a promoter can improve the activity, stability, and C5+ hydrocarbon selectivity of the catalyst.

[0046] Furthermore, based on the total weight of the catalyst, the content of the promoter is 0 - 6% by weight, preferably 0.2 - 4% by weight.

[0047] After reacting for 500 h, the retention rate of chloride ions in the catalyst is greater than or equal to 81%.

[0048] The second aspect of the present invention provides a method for preparing a Fischer-Tropsch synthesis catalyst, including the following steps:

[0049] (1) First knead a Ti source and a Co source to obtain a first mixture;

[0050] (2) Add a Zr source and an optional peptizing agent to the first mixture for second kneading to obtain a second mixture;

[0051] (3) Add an Mn source, a Cl source, an optional promoter, and an optional Co source to the second mixture for third kneading to obtain a matrix catalyst;

[0052] (4) Dry and calcine the matrix catalyst to obtain a Fischer-Tropsch synthesis catalyst;

[0053] Among them, the dosages of the Co source, Mn source, Cl source, Zr source, Ti source and cocatalyst are such that based on the total weight of the catalyst, the content of Co is 10-45 wt%, the content of Mn is 0.01-2.5 wt%, the content of Cl is 0.01-1.5%, the content of ZrO₂ is 0.5-8 wt%, the content of titanium dioxide is 35-85 wt%, and the content of cocatalyst is 0-6 wt%. The molar ratio of Cl to Zr is 1:20-1:0.1.

[0054] The inventors of the present invention unexpectedly found that for the catalyst prepared by the method of the present invention, ZrO₂ can significantly inhibit the growth of the active phase metal cobalt grains in the catalyst, thereby maintaining the stability of the catalyst, and in the catalyst, the retention rate of chloride ions can reach more than 81%.

[0055] Preferably, the Co source is selected from at least one of cobalt nitrate, cobalt carbonate, cobalt acetate, cobalt hydroxide and cobalt chloride.

[0056] Preferably, the Zr source is selected from at least one of ZrO₂, zirconyl nitrate and zirconyl chloride.

[0057] Preferably, the Mn source is selected from at least one of MnO₂, manganese acetate, manganese nitrate and manganese chloride.

[0058] Preferably, the titanium source is selected from at least one of TiO₂, titanium chloride, zirconyl chloride, titanium hydroxide and tetrabutyl titanate.

[0059] Preferably, the cocatalyst source is selected from at least one of chloroplatinic acid, ruthenium trichloride, rhodium trichloride, palladium chloride, yttrium nitrate, ammonium perrhenate, iron nitrate, vanadyl trichloride, pseudoboehmite and lanthanum nitrate.

[0060] Preferably, the Cl source is selected from at least one of cobalt chloride, zirconyl chloride, manganese chloride and hydrochloric acid.

[0061] In a preferred embodiment, the Co source and / or the Cl source is cobalt chloride.

[0062] In the present invention, when the Co source, Mn source, Cl source, Zr source and Ti source are all solid substances, in order to facilitate kneading and molding, preferably a peptizing agent is added thereto. The peptizing agent is used to peptize the added oxides such as TiO₂ and ZrO₂, so that it is more easily molded and interacts with other components in the catalyst. Preferably, the peptizing agent is selected from at least one of glacial acetic acid, citric acid, nitric acid, hydrochloric acid, ammonia water and ammonium bicarbonate.

[0063] Preferably, the drying conditions include: temperature of 80-150 °C and time of 2-48 h.

[0064] Preferably, the conditions for roasting include: temperature is 300 - 650 °C, preferably 400 - 580 °C; time is 1 - 40 h; preferably 2 - 20 h.

[0065] For the convenience of transportation and further improving the activity of the catalyst, preferably, no reduction treatment is carried out during the preparation process, and in-situ reduction treatment is carried out on the catalyst before use to obtain a reduced Fischer-Tropsch synthesis catalyst.

[0066] In a preferred specific embodiment, the conditions for the reduction treatment include: reduction at 250 - 400 °C for 5 - 100 h in an H2 atmosphere.

[0067] The method of the present invention has simple process steps, the obtained catalyst has low methane selectivity and high activity. More particularly, the catalyst has excellent stability and is particularly suitable for the fixed-bed Fischer-Tropsch synthesis process.

[0068] The third aspect of the present invention provides the application of the Fischer-Tropsch synthesis catalyst described in the first aspect of the present invention and / or the Fischer-Tropsch synthesis catalyst prepared by the method described in the second aspect of the present invention in the Fischer-Tropsch synthesis reaction.

[0069] According to the present invention, among them, the grain size of metallic cobalt in the catalyst before the reaction is D0; after reacting for 20 h, the grain size of metallic cobalt in the catalyst is D1; after reacting for 500 h, the grain size of metallic cobalt in the catalyst is D2; (D1 - D0) / D0 × 100% ≤ 20%; (D2 - D0) / D0 × 100% ≤ 35%.

[0070] Furthermore, (D1 - D0) / D0 × 100% is 0 - 17%; (D2 - D0) / D0 × 100% is 5 - 30%.

[0071] The present invention will be described in detail below through examples.

[0072] The tests involved in the examples and comparative examples are as follows:

[0073] The content of each component in the catalyst is measured by XRF;

[0074] In the catalyst, the molar ratio of Cl to Zr is measured by the XRF method;

[0075] In the catalyst, the grain size of metallic cobalt is calculated by the Scherrer formula of XRD

[0076] The content test of anatase crystal form in titanium dioxide powder and the catalyst before and after the reaction is measured by XRD.

[0077] Example 1

[0078] 200 g of TiO2 powder (specific surface area is 30 - 70 m2 30.4 g of cobalt hydroxide (where the anatase crystal form content is 90% by weight) was placed in a kneader and kneaded for the first time for 30 minutes. Then, 21.7 g of zirconyl nitrate (ZrO(NO3)2·2H2O) and 15 g of glacial acetic acid were dissolved in 15 ml of deionized water and added to the kneader to continue the second kneading for 30 minutes. 3.3 g of manganese nitrate (Mn(NO3)2), 96.5 g of cobalt nitrate (Co(NO3)2·6H2O), and 1.5 g of anhydrous cobalt chloride (CoCl2) were dissolved in 85 g of deionized water and added to the kneader for the third kneading for 60 minutes. After mixing evenly in the kneader, it was extruded into pellets, dried at 120 °C for 10 h, and then calcined at 550 °C for 3 h to obtain catalyst A1.

[0079] By XRF testing, based on the total weight of catalyst A1, the content of Co was 15% by weight, the content of Mn was 0.4% by weight, the content of Cl was 0.3% by weight, the content of ZrO2 was 4.3% by weight, and the content of titanium dioxide was 74.9% by weight (in the titanium dioxide, the content of anatase crystal form titanium dioxide was 72% by weight; the content of rutile crystal form titanium dioxide was 28% by weight).

[0080] Example 2

[0081] 200 g of TiO2 powder (the same as in Example 1) and 91.2 g of cobalt hydroxide were placed in a kneader and kneaded for the first time for 30 minutes. Then, 43.4 g of zirconyl nitrate (ZrO(NO3)2·2H2O) and 25 g of glacial acetic acid were dissolved in 30 g of deionized water and added to the kneader to continue the second kneading for 30 minutes. 13.2 g of manganese nitrate (Mn(NO3)2), 96.5 g of cobalt nitrate (Co(NO3)2·6H2O), and 4.5 g of anhydrous cobalt chloride (CoCl2) were dissolved in 70 g of deionized water and then added to the kneader for the third kneading for 60 minutes. After mixing evenly in the kneader, it was extruded into pellets, dried at 140 °C for 18 h, and then calcined at 420 °C for 10 h to obtain catalyst A2.

[0082] By XRF testing, based on the total weight of catalyst A2, the content of Co was 24% by weight, the content of Mn was 1.2% by weight, the content of Cl was 0.6% by weight, the content of ZrO2 was 7% by weight, and the content of titanium dioxide was 60% by weight (in the titanium dioxide, the content of anatase crystal form titanium dioxide was 80% by weight; the content of rutile crystal form titanium dioxide was 20% by weight).

[0083] Example 3

[0084] After first kneading 200 g of TiO2 powder (the same as in Example 1) and 162.4 g of cobalt hydroxide in a kneader for 30 minutes, 43.4 g of zirconyl nitrate (ZrO(NO3)2·2H2O) and 15 g of glacial acetic acid were dissolved in 50 g of deionized water and added to the kneader for second kneading for 30 minutes. 22 g of manganese nitrate (Mn(NO3)2), 193 g of cobalt nitrate (Co(NO3)2·6H2O) and 13 g of anhydrous cobalt chloride (CoCl2) were dissolved in 90 ml of deionized water and then added to the kneader for third kneading for 60 minutes. After mixing evenly in the kneader, it was extruded into pellets, dried at 90 °C for 5 h, and then calcined at 500 °C for 10 h to obtain catalyst A3.

[0085] By XRF test, based on the total weight of catalyst A3, the content of Co is 33 wt%, the content of Mn is 1.5 wt%, the content of Cl is 1.1 wt%, the content of ZrO2 is 5.2 wt%, and the content of titanium dioxide is 45 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide is 75 wt%; the content of rutile-type titanium dioxide is 25 wt%).

[0086] Example 4

[0087] 200 g of TiO2 powder (the same as in Example 1) and 236.7 g of cobalt hydroxide were placed in a kneader. After kneading for 30 minutes, 21.7 g of zirconyl nitrate (ZrO(NO3)2·2H2O) and 25 g of glacial acetic acid were dissolved in 15 g of deionized water and added to the kneader. After continuing to knead for 30 minutes, 27.5 g of manganese nitrate (Mn(NO3)2), 96.5 g of cobalt nitrate (Co(NO3)2·6H2O) and 20 g of anhydrous cobalt chloride (CoCl2) were dissolved in 85 g of deionized water and added to the kneader. Continuing to knead, after mixing evenly in the kneader, it was extruded into pellets, dried at 100 °C for 12 h, and then calcined at 600 °C for 2 h to obtain catalyst A4.

[0088] By XRF test, based on the total weight of catalyst A4, the content of Co is 38 wt%, the content of Mn is 1.8 wt%, the content of Cl is 1.4 wt%, the content of ZrO2 is 2 wt%, and the content of titanium dioxide is 43 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide is 64 wt%; the content of rutile-type titanium dioxide is 36 wt%).

[0089] Example 5

[0090] Put 246 g of TiO2 powder (same as in Example 1) and 122 g of cobalt hydroxide into a kneader. After kneading for 30 minutes, dissolve 13.9 g of ZrO2 and 5 g of concentrated hydrochloric acid in 50 g of deionized water and add it to the kneader. After continuing to knead for 30 minutes, dissolve 12.8 g of MnO2 and 8 g of titanium oxychloride (TiOCl2·8H2O) in 65 g of deionized water and then add it to the kneader. Continue kneading. After mixing evenly in the kneader, extrude into strips, dry at 80 °C for 24 h, and then calcine at 360 °C for 7 h to obtain Catalyst A5.

[0091] By XRF test, based on the total weight of Catalyst A5, the content of Co is 20 wt%, the content of Mn is 2 wt%, the content of Cl is 0.08 wt%, the content of ZrO2 is 4 wt%, and the content of titanium dioxide is 65 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide is 85 wt%; the content of rutile-type titanium dioxide is 15 wt%).

[0092] Example 6

[0093] Refer to the method described in Example 1 to prepare a Fischer-Tropsch synthesis catalyst. The difference is that the amount of anhydrous cobalt chloride (CoCl2) used is 0.8 g, and the rest is the same as in Example 1. Finally, Catalyst A6 is obtained.

[0094] By XRF test, based on the total weight of Catalyst A6, the content of Co is 14.8 wt%, the content of Mn is 0.41 wt%, the content of Cl is 0.15 wt%, the content of ZrO2 is 4.4 wt%, and the content of titanium dioxide is 75.3 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide is 72 wt%; the content of rutile-type titanium dioxide is 28 wt%).

[0095] Example 7

[0096] Refer to the method described in Example 1 to prepare a Fischer-Tropsch synthesis catalyst. The difference is that the amount of anhydrous cobalt chloride (CoCl2) used is 10 g, and the rest is the same as in Example 1. Finally, Catalyst A7 is obtained.

[0097] By XRF test, based on the total weight of Catalyst A7, the content of Co is 17 wt%, the content of Mn is 0.4 wt%, the content of Cl is 1.3 wt%, the content of ZrO2 is 4 wt%, and the content of titanium dioxide is 75 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide is 72 wt%; the content of rutile-type titanium dioxide is 28 wt%).

[0098] Example 8

[0099] The Fischer-Tropsch synthesis catalyst was prepared by referring to the method described in Example 1, except that the calcination temperature was 650 °C, and the rest was the same as in Example 1, and finally catalyst A8 was obtained.

[0100] By XRF testing, based on the total weight of catalyst A8, the content of Co was 15 wt%, the content of Mn was 0.4 wt%, the content of Cl was 0.12 wt%, the content of ZrO2 was 4.3 wt%, and the content of titanium dioxide was 74.9 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide was 55 wt%; the content of rutile-type titanium dioxide was 45 wt%).

[0101] Example 9

[0102] The Fischer-Tropsch synthesis catalyst was prepared by referring to the method described in Example 1, except that the content of anatase-type titanium dioxide in the TiO2 powder used was 60 wt%, and the rest was the same as in Example 1, and finally catalyst A9 was obtained.

[0103] By XRF testing, based on the total weight of catalyst A9, the content of Co was 15 wt%, the content of Mn was 0.4 wt%, the content of Cl was 0.3 wt%, the content of ZrO2 was 4.3 wt%, and the content of titanium dioxide was 74.9 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide was 51 wt%; the content of rutile-type titanium dioxide was 49 wt%).

[0104] Example 10

[0105] The Fischer-Tropsch synthesis catalyst was prepared by referring to the method described in Example 1, except that 45 g of acidic silica sol with a SiO2 content of 20 wt% was added, and the rest was the same as in Example 1, and finally catalyst A10 was obtained.

[0106] By XRF testing, based on the total weight of catalyst A9, the content of Co was 14 wt%, the content of Mn was 3.6 wt%, the content of Cl was 0.3 wt%, the content of ZrO2 was 4 wt%, the content of SiO2 was 3.5 wt%, and the content of titanium dioxide was 73 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide was 72 wt%; the content of rutile-type titanium dioxide was 28 wt%).

[0107] Comparative Example 1

[0108] Dissolve 44 g of Co(NO3)2·6H2O in 15 g of deionized water and stir to prepare a solution. Add the above solution to 100 g of dried TiO2 support (where the anatase crystal form content is 100 wt%). After drying and dehydrating at 85 °C for 4 hours, raise the temperature to 120 °C and dry for 10 h. Then dissolve 36.9 g of Co(NO3)2·6H2O in 15 g of deionized water to prepare a solution. Add the dried sample to this solution, and again dry and dehydrate at 85 °C for 4 hours, then raise the temperature to 120 °C and dry for 10 h. Then heat up to 250 °C at a rate of 1 °C / min and calcine for 4 h to prepare catalyst D1.

[0109] By XRF testing, based on the total weight of catalyst D1, the content of Co is 14.2 wt%, and the content of titanium dioxide is 81.3 wt% (in the titanium dioxide, the content of anatase crystal form titanium dioxide is 94 wt%; the content of rutile crystal form titanium dioxide is 6 wt%).

[0110] Comparative Example 2

[0111] Replace TiO2 in Comparative Example 1 with ZrO2, and the rest is the same as Comparative Example 1 to prepare catalyst D2.

[0112] By XRF testing, based on the total weight of catalyst D2, the content of Co is 14.5 wt%, and the content of ZrO2 is 81 wt%.

[0113] Comparative Example 3

[0114] Refer to the method described in Example 1 to prepare the catalyst. The difference is that zirconyl nitrate is not used and the calcination temperature of the catalyst is 500 °C, and the rest is the same as Example 1. Finally, catalyst D3 is prepared.

[0115] By XRF testing, based on the total weight of catalyst D3, the content of Co is 15.5 wt%, the content of Mn is 0.5 wt%, the content of Cl is 0.3 wt%, and the content of titanium dioxide is 76 wt% (in the titanium dioxide, the content of anatase crystal form titanium dioxide is 65 wt%; the content of rutile crystal form titanium dioxide is 35 wt%).

[0116] Comparative Example 4

[0117] Refer to the method described in Example 1 to prepare the catalyst. The difference is that 6 g of cobalt acetate is used to replace 1.5 g of anhydrous cobalt chloride, and the rest is the same as Example 1. Finally, catalyst D4 is prepared.

[0118] By XRF testing, based on the total weight of catalyst D4, the content of Co is 15.5 wt%, the content of Mn is 0.39 wt%, the content of ZrO2 is 3.9 wt%, and the content of titanium dioxide is 74.6 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide is 72 wt%; the content of rutile-type titanium dioxide is 28 wt%).

[0119] Comparative Example 5

[0120] The Fischer-Tropsch synthesis catalyst was prepared by referring to the method described in Example 1, except that the amount of anhydrous cobalt chloride (CoCl2) used was 12 g, and the rest was the same as in Example 1, and finally catalyst D5 was prepared.

[0121] By XRF testing, based on the total weight of catalyst D5, the content of Co is 16 wt%, the content of Mn is 0.4 wt%, the content of Cl is 2 wt%, the content of ZrO2 is 4.1 wt%, and the content of titanium dioxide is 74 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide is 72 wt%; the content of rutile-type titanium dioxide is 28 wt%).

[0122] Comparative Example 6

[0123] The Fischer-Tropsch synthesis catalyst was prepared by referring to the method described in Example 1, except that the amount of zirconium oxynitrate used was 1.7 g, and the rest was the same as in Example 1, and finally catalyst D6 was prepared.

[0124] By XRF testing, based on the total weight of catalyst D6, the content of Co is 15.4 wt%, the content of Mn is 0.44 wt%, the content of Cl is 0.31 wt%, the content of ZrO2 is 0.3 wt%, and the content of titanium dioxide is 78.4 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide is 70 wt%; the content of rutile-type titanium dioxide is 30 wt%).

[0125] Comparative Example 7

[0126] The Fischer-Tropsch synthesis catalyst was prepared by referring to the method described in Example 1, except that the amount of zirconium oxynitrate used was 68 g, and the rest was the same as in Example 1, and finally catalyst D7 was prepared.

[0127] By XRF testing, based on the total weight of catalyst D7, the content of Co is 13.5 wt%, the content of Mn is 0.36 wt%, the content of Cl is 0.33 wt%, the content of ZrO2 is 10.9 wt%, and the content of titanium dioxide is 70 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide is 76 wt%; the content of rutile-type titanium dioxide is 24 wt%).

[0128] Comparative Example 8

[0129] The Fischer-Tropsch synthesis catalyst was prepared by referring to the method described in Example 1. The difference is that 21.7 g of zirconyl nitrate was replaced by 9 g of magnesium oxide, and the rest was the same as in Example 1. Finally, catalyst D8 was obtained.

[0130] By XRF testing, based on the total weight of catalyst D8, the content of Co was 15.1 wt%, the content of Mn was 0.41 wt%, the content of Cl was 0.22 wt%, the content of MgO was 3.9 wt%, and the content of titanium dioxide was 75 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide was 65 wt%; the content of rutile-type titanium dioxide was 35 wt%).

[0131] Comparative Example 9

[0132] The Fischer-Tropsch synthesis catalyst was prepared by referring to the method described in Example 1. The difference is that 21.7 g of zirconyl nitrate was replaced by 9 g of cerium dioxide, and the rest was the same as in Example 1. Finally, catalyst D9 was obtained.

[0133] By XRF testing, based on the total weight of catalyst D8, the content of Co was 15.1 wt%, the content of Mn was 0.41 wt%, the content of Cl was 0.21 wt%, the content of CeO2 was 3.9 wt%, and the content of titanium dioxide was 75 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide was 67 wt%; the content of rutile-type titanium dioxide was 33 wt%).

[0134] Comparative Example 10

[0135] The Fischer-Tropsch synthesis catalyst was prepared by referring to the method described in Example 1. The difference is that the content of zirconyl nitrate was adjusted to 2 g, and 15 g of glacial acetic acid was replaced by 15 g of concentrated hydrochloric acid, and the rest was the same as in Example 1. Finally, catalyst D10 was obtained.

[0136] By XRF testing, based on the total weight of catalyst D10, the content of Co was 16 wt%, the content of Mn was 0.4 wt%, the content of Cl was 1.2 wt%, the content of ZrO2 was 0.1 wt%, and the content of titanium dioxide was 75.8 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide was 65 wt%; the content of rutile-type titanium dioxide was 35 wt%).

[0137] Comparative Example 11

[0138] The Fischer-Tropsch synthesis catalyst was prepared by referring to the method described in Example 1. The difference is that 21.7 g of zirconyl nitrate was replaced by 35 g of ZrO2, and 1.5 g of anhydrous cobalt chloride (CoCl2) was adjusted to 0.5 g, and the rest was the same as in Example 1. Finally, catalyst D11 was obtained.

[0139] By XRF test, based on the total weight of catalyst D11, the content of Co is 13 wt%, the content of Mn is 0.4 wt%, the content of Cl is 0.1 wt%, the content of ZrO2 is 12 wt%, and the content of titanium dioxide is 70 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide is 81 wt%; the content of rutile-type titanium dioxide is 19 wt%).

[0140] Comparative Example 12

[0141] Put 200 g of TiO2 powder (specific surface area of 30 - 70 m 2 / g, where the anatase-type content is 90 wt%) and 30.4 g of cobalt hydroxide into a kneader. Dissolve 3.3 g of manganese nitrate (Mn(NO3)2), 21.7 g of zirconyl nitrate (ZrO(NO3)2·2H2O), 96.5 g of cobalt nitrate (Co(NO3)2·6H2O), 1.5 g of anhydrous cobalt chloride (CoCl2) and 15 g of glacial acetic acid in 85 g of deionized water, then add it to the kneader and knead for 60 minutes. After kneading evenly in the kneader, extrude into strips, dry at 120 °C for 10 h, and then calcine at 550 °C for 3 h to obtain catalyst D12.

[0142] By XRF test, based on the total weight of catalyst D12, the content of Co is 15 wt%, the content of Mn is 0.4 wt%, the content of Cl is 0.3 wt%, the content of ZrO2 is 4.3 wt%, and the content of titanium dioxide is 74.9 wt% (in the titanium dioxide, the content of anatase-type titanium dioxide is 72 wt%; the content of rutile-type titanium dioxide is 28 wt%).

[0143] The molar ratio of Cl to Zr, the Co3O4 crystal grain size, and the titanium dioxide crystal form in each catalyst in the examples and comparative examples are shown in Table 1.

[0144] Table 1

[0145]

[0146]

[0147] Catalyst performance test

[0148] Load catalysts A1 - A9 and D1 - D10 into a 10 mL fixed-bed reactor respectively, and the catalyst loading is 0.5 g for all. First, activate the catalysts in the fixed-bed reactor at 350 °C in a H2 atmosphere for 20 h. After the reduction is completed, cool down to 180 °C, switch to the reaction gas, and raise the temperature to the reaction temperature for catalyst performance evaluation.

[0149] The conditions for evaluating the catalyst performance include: in syngas with H2 / CO (molar ratio) = 2, at 215 °C and 2 MPa, and the space velocity is 3 L / (g cat· h).

[0150] The structural parameters of the catalyst at different reaction stages are shown in Table 2. The catalytic performance of the catalyst is shown in Table 3.

[0151] Table 2

[0152]

[0153]

[0154] Table 3

[0155]

[0156] From the results in Tables 1 - 3 and by comparing the catalysts prepared in Examples 1 - 10 and Comparative Examples 1 - 12, it can be seen that for the catalyst prepared by the method of the present invention, when the Co content is 10 - 45 wt%, the Mn content is 0.01 - 2.5 wt%, the Cl content is 0.01 - 1.5 wt%, the ZrO2 content is 0.5 - 8 wt%, the carrier TiO2 content is 35 - 85 wt%, and the molar ratio of Cl to Zr is 1:20 - 1:0.1, after reacting for 20 h, the growth rate of the grain size of metallic cobalt does not exceed 17%, and the CO conversion rate can reach more than 54%, and the CH4 selectivity is below 5.9%. After reacting for 500 h, the growth rate of the grain size of metallic cobalt does not exceed 28%. At this time, the retention rate of chloride ions in the catalyst is above 81%, and the CO conversion rate reaches above 53%, and the CH4 selectivity is below 6.1%. It has good catalytic activity and catalytic stability.

[0157] Although the CO conversion rate of the catalyst in Comparative Example 12 is relatively stable, the methane selectivity of the catalyst gradually increases.

[0158] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and all fall within the protection scope of the present invention.

Claims

1. A Fischer-Tropsch synthesis catalyst, characterized in that, Based on the total weight of the catalyst, the Fischer-Tropsch synthesis catalyst comprises: 10-45% by weight of Co, 0.01-2.5% by weight of Mn, 0.01-1.5% by weight of Cl, 0.5-8% by weight of ZrO₂, 35-85% by weight of the carrier TiO₂; wherein, the molar ratio of Cl to Zr is 1:20 - 1:0.1; The grain size of cobalt tetroxide in the catalyst is 16-27 nm.

2. The catalyst according to claim 1, wherein, The titanium dioxide includes anatase-type titanium dioxide and rutile-type titanium dioxide, and the content of anatase-type titanium dioxide in the titanium dioxide is greater than that of rutile-type titanium dioxide.

3. The catalyst according to claim 2, wherein, Based on the total amount of the titanium dioxide, the content of anatase-type titanium dioxide is greater than 50% by weight, and the content of rutile-type titanium dioxide is less than 40% by weight.

4. The catalyst according to claim 3, wherein, Based on the total amount of the titanium dioxide, the content of anatase-type titanium dioxide is greater than 60% by weight, and the content of rutile-type titanium dioxide is less than 30% by weight.

5. The catalyst according to claim 1, wherein, Based on the total weight of the catalyst, the Fischer-Tropsch synthesis catalyst comprises: 15-40% by weight of Co, 0.1-1.3% by weight of Mn, 0.08-1.2% by weight of Cl, 0.8-6.5% by weight of ZrO₂, 45-80% by weight of titanium dioxide; wherein, the molar ratio of Cl to Zr is 1:15 - 1:0.2; The grain size of cobalt tetroxide in the catalyst is 18-25 nm.

6. The catalyst according to any one of claims 1-5, wherein, The catalyst further comprises a promoter selected from at least one of platinum, ruthenium, rhodium, palladium, yttrium, rhenium, iron, vanadium, silicon, aluminum and lanthanum.

7. The catalyst according to claim 6, wherein, Based on the total weight of the catalyst, the content of the promoter is 0-6% by weight.

8. A method for preparing the Fischer-Tropsch synthesis catalyst according to any one of claims 1-7, comprising the following steps: (1) First kneading a Ti source and a Co source to obtain a first mixture; (2) Adding a Zr source and an optional peptizing agent to the first mixture for second kneading to obtain a second mixture; (3) Adding an Mn source, a Cl source, an optional promoter and an optional Co source to the second mixture for third kneading to obtain a matrix catalyst; (4) Drying and calcining the matrix catalyst to obtain the Fischer-Tropsch synthesis catalyst; wherein, the dosages of the Co source, Mn source, Cl source, Zr source, Ti source and promoter are such that based on the total weight of the catalyst, the content of Co is 10-45% by weight, the content of Mn is 0.01-2.5% by weight, the content of Cl is 0.01-1.5%, the content of ZrO₂ is 0.5-8% by weight, the content of titanium dioxide is 35-85% by weight, the content of the promoter is 0-6% by weight, and the molar ratio of Cl to Zr is 1:20 - 1:0.

1.

9. The method according to claim 8, wherein, The Co source is selected from at least one of cobalt nitrate, cobalt carbonate, cobalt acetate, cobalt hydroxide and cobalt chloride; and / or, the Zr source is selected from at least one of ZrO₂, zirconyl nitrate and zirconium oxychloride; and / or, the Mn source is selected from at least one of MnO₂, manganese acetate, manganese nitrate and manganese chloride; And / or, the Ti source is selected from at least one of TiO2, titanium chloride, titanium oxychloride, titanium hydroxide, and tetrabutyl titanate; And / or, the promoter source is selected from at least one of chloroplatinic acid, ruthenium trichloride, rhodium trichloride, palladium chloride, yttrium nitrate, ammonium perrhenate, iron nitrate, vanadium oxychloride, silica sol, pseudoboehmite, and lanthanum nitrate.

10. The method according to claim 8, wherein, The peptizing agent is selected from at least one of glacial acetic acid, citric acid, nitric acid, hydrochloric acid, ammonia water, and ammonium bicarbonate.

11. The method according to any one of claims 8, wherein, The Cl source is selected from at least one of cobalt chloride, zirconium oxychloride, manganese chloride, and hydrochloric acid.

12. The method according to any one of claims 8-11, wherein, The time of the first kneading is 12 - 120 min, the time of the second kneading is 12 - 120 min, and the time of the third kneading is 12 - 120 min; And / or, the drying conditions include: temperature is 80 - 150 °C, and time is 2 - 48 h; And / or, the calcination conditions include: temperature is 300 - 650 °C, and time is 1 - 40 h.

13. Application of the Fischer - Tropsch synthesis catalyst according to any one of claims 1 - 7 and / or the Fischer - Tropsch synthesis catalyst prepared by the method according to any one of claims 8 - 12 in the Fischer - Tropsch synthesis reaction.

14. The application according to claim 13, wherein, The grain size of metallic cobalt in the catalyst before reaction is D0; after reacting for 20 h, the grain size of metallic cobalt in the catalyst is D1; after reacting for 500 h, the grain size of metallic cobalt in the catalyst is D2; (D1 - D0) / D0×100% ≤ 20%; (D2 - D0) / D0×100% ≤ 35%.

15. The application according to claim 14, wherein, (D1 - D0) / D0×100% is 0 - 17%; (D2 - D0) / D0×100% is 5 - 30%.

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