Nickel-based catalyst system, method of making and method of producing alkanes

Abstract

The application provides a nickel-based catalyst, a preparation method and a method for producing alkanes. The application discloses a nickel-based catalyst, wherein the carrier is an Al2O3 / TiO2 composite carrier, the catalyst is divided into two sections, the first section is a composite carrier and an active component nickel supported on the carrier, and the second section is a composite carrier and an active component molybdenum, cobalt and nickel supported on the carrier. The application further discloses a method for producing alkanes from coal chemical raw materials, wherein the method uses MTO / MTP by-products as raw materials and produces alkanes under the action of the nickel-based catalyst. The nickel-based catalyst and the production method have the advantages that the raw materials do not need to be subjected to the separation and pretreatment of oxides, the hydrogenation effect is remarkable, and the yield of saturated alkanes is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of producing alkanes from coal chemical raw materials, and particularly relates to a nickel-based catalyst system, a preparation method thereof and a method for producing alkanes. BACKGROUND

[0002] The traditional method for producing alkanes is to use petroleum hydrocarbons as raw materials to produce alkanes through catalysis and steam cracking. With the increasing scarcity of petroleum resources, more and more attention has been paid to the process of producing chemical products through non-petroleum routes. China has relatively abundant coal reserves, and the production of organic chemical raw materials and oil products through coal chemical routes has received widespread attention in recent years. The most typical coal chemical route includes coal-to-olefins and coal-to-oil. Among them, the process of coal-to-ethylene, propylene and other low-carbon olefins, including methanol-to-olefins (MTO), methanol-to-propylene (MTP), Fisher-Tropsch to olefins (FTTO), etc., coal-to-oil, including direct coal liquefaction to oil, coal-to-oil (gas-to-liquids, GTL), methanol-to-gasoine (MTG), etc. MTO, MTP and GTL have all built large-scale industrialized devices and achieved industrialization, and FTTO technology has also made significant progress. Methanol-to-olefins is a new process for increasing olefin production, which has developed rapidly in China in recent years. In 2016, China's MTO capacity exceeded 11 million tons / year. By 2021, China's MTO capacity is expected to reach 24 million tons / year. MTO process produces 4-6% of C5+ gasoline fraction as by-product, which contains more than 70% of olefins and more than 10% of aromatic hydrocarbons.

[0003] Similar to the MTO process technology, the MTP process technology also produces a large amount of C5+ heavy components as by-product, which is about 40% of propylene, contains more than 30% of olefins, and the content of aromatic hydrocarbons reaches more than 35%.

[0004] Therefore, exploring the method of producing alkanes from MTO / MTP byproducts has become a hot spot in scientific research. Patent USP5714662 discloses a method of separating byproducts and respectively performing etherification, dimerization, isomerization, hydration and hydrogenation reactions, which can convert byproducts into high octane components and other valuable products. Patent USP7030284 discloses a method of hydrogenating heavy olefins and oxides into alkanes. This technology uses a catalyst with sulfided Ni, Co, Mo and Ni, Co, W as active metal components and alumina as carrier to hydrogenate heavy olefins and oxides, and the reaction temperature is 180-350℃ and the reaction pressure is 10-20MPa. The reaction conditions are extremely harsh. Patent CN101092322A discloses a hydrogenation method with a reaction temperature of 220-300℃ and a reaction pressure of 0.8-2.0MPa, but the oxides need to be separated before hydrogenation, which will cause a long process route and increase the cost. SUMMARY

[0005] In order to solve the above problems in the prior art, the present application provides a nickel-based catalyst system, a preparation method thereof and a method for producing alkanes.

[0006] In a first aspect, the present application provides a nickel-based catalyst system, which comprises a first-stage catalyst and a second-stage catalyst.

[0007] The first-stage catalyst comprises a first-stage composite carrier and an active component nickel supported on the first-stage composite carrier.

[0008] The second-stage catalyst comprises a second-stage composite carrier and an active component molybdenum, cobalt and nickel supported on the second-stage composite carrier.

[0009] The first-stage composite carrier and the second-stage composite carrier are each independently an Al2O3 / TiO2 composite carrier.

[0010] The active components nickel, molybdenum and cobalt in the catalyst system of the present application are in the form of nickel oxide, molybdenum oxide and cobalt oxide, respectively, in the finished first-stage catalyst and second-stage catalyst, and need to be reduced to nickel, molybdenum and cobalt, respectively, before the catalyst is applied.

[0011] As a specific embodiment of the present application, the content of the active component nickel in the first-stage catalyst is 12-18wt%, preferably 14-17wt%, based on the weight of the first-stage catalyst.

[0012] As a specific embodiment of the present application, the content of the active component nickel in the form of nickel oxide in the two-stage catalyst is 2-5%, preferably 3-4%, based on the weight of the two-stage catalyst; the content of the active component molybdenum oxide is 10-13%, preferably 11-12%; and the content of the active component cobalt oxide is 1-4%, preferably 2-3%.

[0013] As a specific embodiment of the present application, the weight ratio of TiO2 to Al2O3 in the one-stage composite carrier and the two-stage composite carrier is independently 1:(4-6), to obtain an alumina-titanium composite carrier. To make the composite carrier more active and support more catalyst, the composite carrier can be activated before impregnation of the active component; for example, but not limited to, ion exchange of the alumina-titanium composite carrier with an ammonium salt solution at 50-100°C for 2-4h to obtain an activated composite carrier.

[0014] As a specific embodiment of the present application, the composite carrier has a common shape, for example, but not limited to, clover shape, strip shape or cylindrical shape.

[0015] The above raw materials in the present application can be self-made or commercially available, and the present application does not make special limitations thereto.

[0016] In the second aspect, the present application provides a preparation method of a nickel-based catalyst, which comprises impregnating a metal active component nickel on a one-stage composite carrier to obtain a one-stage catalyst; and impregnating metal active components molybdenum oxide, cobalt oxide and nickel oxide on a two-stage composite carrier to obtain a two-stage catalyst.

[0017] As a specific embodiment of the present application, specifically, the preparation method of the one-stage catalyst comprises impregnating a metal active component nickel on a one-stage composite carrier, and then drying and calcining to obtain the one-stage catalyst; the impregnation time is 3-5h; the drying temperature is 100-150°C, and the drying time is 5-7h; the calcination temperature is 550-650°C, and the calcination time is 4-6h.

[0018] The preparation method of the two-stage catalyst comprises impregnating a metal active component nickel on a two-stage composite carrier, and then drying and calcining to obtain the two-stage catalyst; the impregnation time is 3-5h; the drying temperature is 100-150°C, and the drying time is 5-7h; the calcination temperature is 650-750°C, and the calcination time is 4-6h.

[0019] The preparation method of the one-stage composite carrier and the two-stage composite carrier is independently as follows: an aluminum-titanium sol is prepared by a coprecipitation method, and then is subjected to pressure filtration, extrusion and drying and calcination to obtain the one-stage composite carrier and the two-stage composite carrier; the drying temperature is 100-150°C, and the drying time is 8-12h; the calcination temperature is 550-650°C, and the calcination time is 3-5h.

[0020] The present application does not have special limitation on impregnation, and any known impregnation method in the art can be used to prepare the primary catalyst and the secondary catalyst.

[0021] In a third aspect, the present application provides a method for producing alkanes, which uses MTO / MTP by-products as raw materials and produces alkanes under the action of a nickel-based catalyst system.

[0022] It should be noted that the content of C1-C4 in the MTO / MTP by-products is less than 0.5%, the content of C5 is about 40%, the content of C6-C8 is greater than 40%, the content of C9 and above is about 15%, and the total olefins are about 70%.

[0023] The MTO / MTP by-product raw materials are separated into C5 components and C6 and above components in the C5 removal column, the C5 components are sent to the newly added olefin cracking unit, and the C6 and above components are sent to the C6-C9 hydrogenation unit.

[0024] As a specific embodiment of the present application, the feed containing MTO / MTP by-products and hydrogen is contacted with the primary catalyst to perform the primary reaction, the feed containing MTO / MTP by-products and hydrogen is contacted with the secondary catalyst to perform the secondary reaction, and the MTO / MTP by-products are hydrogenation converted into saturated alkanes under the catalysis of the catalyst system.

[0025] As a specific embodiment of the present application, the reaction device used is any suitable reaction device known to those skilled in the art, for example but not limited to a fixed isothermal bed hydrogenation reaction device.

[0026] As a specific embodiment of the present application, the process conditions of the catalytic hydrogenation are as follows: the MTO / MTP by-products and hydrogen are fed at a volume ratio of 1:300-500, the primary reaction temperature is 150-200°C, the reaction pressure is 2.3-3.2 MPa, the feed volume space velocity is 0.1-0.6 h -1 -1, the secondary reaction temperature is 220-280°C, the reaction pressure is 2.3-3.2 MPa, and the feed volume space velocity is 0.6-1.5 h -1 .

[0027] As a specific embodiment of the present application, the process conditions are preferably as follows: the primary reaction temperature is 160-180°C, the reaction pressure is 2.5-2.9 MPa, the feed volume space velocity is 0.3-0.5 h -1 -1, the secondary reaction temperature is 230-260°C, the reaction pressure is 2.5-2.9 MPa, and the feed volume space velocity is 0.8-1.2 h -1 .

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] 1、The MTO / MTP by-product raw material of the present application is rich in oxides, and compared with the hydrogenation effect of the catalyst in the prior art, the hydrogenation effect is remarkable by using the nickel-based catalyst and the production method of the present application without pretreatment work such as separation of oxides of the raw material.

[0030] 2、It can be known from the embodiments of the present application that the hydrogenation effect is remarkable by using the nickel-based catalyst and the production method of the present application without pretreatment work such as separation of oxides of the raw material, and the saturated alkane content is > 99%.

[0031] 3、The present application widens the use of the MTO / MTP by-product raw material by the two-stage hydrogenation process, and increases the obtaining method of alkane, and has wide market application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a process flow diagram for producing alkane in the embodiments of the present application. DETAILED DESCRIPTION

[0033] The present application will be further described below in combination with specific embodiments, but does not constitute any limitation on the present application.

[0034] In the embodiments of the present application, the feed air speed is the ratio of the feed mass per hour to the catalyst mass, and the unit is h -1 .

[0035] In the embodiments of the present application, the C1-C4 content in the MTO / MTP by-product is 0.2%, the C5 content is 42%, the C6-C8 content is 40%, the C9 and above content is 15%, and the total olefin content is 70%.

[0036] In the embodiments of the present application, two-stage hydrogenation evaluation devices are used, the MTO / MTP by-product is subjected to C5 removal tower, the C5 and light distillate are introduced into the olefin cracking unit to produce products, the C6+ distillate is introduced into the hydrogenation first reactor and the hydrogenation second reactor in turn and mixed with hydrogen to pass through the catalyst for catalytic hydrogenation, the MTO / MTP by-product and hydrogen are fed according to the volume ratio of 1:400, and under suitable process conditions, alkane products are produced.

[0037] Embodiment 1

[0038] The present embodiment provides a one-stage nickel-based catalyst and a preparation method, and the specific steps are as follows:

[0039] S1, preparing an alumina-titanium oxide composite carrier

[0040] TiO2 and Al2O3 are mixed in a mass ratio of 1:5, an aluminum titanium sol is prepared by a co-precipitation method, and then the aluminum titanium sol is filtered, extruded, dried at 120℃ for 10 hours, and calcined at 600℃ for 4 hours to obtain an alumina-titania composite carrier.

[0041] S2, a preparation method of a first-stage nickel-based catalyst

[0042] The alumina-titania composite carrier is ion exchanged with an NH4Cl solution at 65℃, and the ion-exchanged composite carrier is obtained after ion exchange for 3 hours.

[0043] 47.03g of nickel nitrate is added to 200ml of water and stirred to dissolve, and the pH value is adjusted to 5 to form a nickel nitrate solution.

[0044] 100g of the ion-exchanged composite carrier is immersed in the above nickel nitrate solution for 4 hours, then dried at 120℃ for 6 hours, and then calcined at 600℃ for 5 hours to obtain a first-stage nickel-based catalyst A.

[0045] The nickel oxide content of the first-stage nickel-based catalyst obtained in Example 1 is 12%.

[0046] Examples 2-4

[0047] According to the preparation method of the carrier and the first-stage catalyst described in Example 1, specific catalysts are prepared, and the difference is that the concentration of the nickel nitrate aqueous solution for immersion is different, resulting in different active metal component contents.

[0048] The first-stage nickel-based catalysts B, C, and D obtained in Examples 2-4.

[0049] Example 5

[0050] This example provides a second-stage nickel-based catalyst and a preparation method, and the specific steps are as follows:

[0051] 13.6g of ammonium molybdate is added to 200ml of water and stirred to dissolve to form an ammonium molybdate solution. 11.766g of nickel nitrate is added to 200ml of water and stirred to dissolve to form a nickel nitrate solution. 3.93g of cobalt nitrate is added to 200ml of water and stirred to dissolve to form a cobalt nitrate solution.

[0052] The composite carrier 100 g obtained in step S1 of Example 1 was first immersed in an aqueous ammonium molybdate solution, impregnated for 4 h, then dried at a temperature of 110°C for 5 h, calcined at a temperature of 700°C for 6 h, then immersed in an appropriate amount of aqueous nickel nitrate solution, impregnated for 4 h, then dried at a temperature of 110°C for 5 h, calcined at a temperature of 700°C for 6 h, and finally immersed in an aqueous cobalt nitrate solution, impregnated for 4 h, then dried at a temperature of 110°C for 5 h, calcined at a temperature of 700°C for 6 h, to finally obtain a two-stage nickel-based catalyst E.

[0053] The two-stage nickel-based catalyst E obtained in Example 5 has a molybdenum oxide content of 10%, a nickel oxide content of 3%, and a cobalt oxide content of 1%.

[0054] Examples 6-12

[0055] According to the carrier preparation method described in Example 1 and the two-stage nickel-based catalyst preparation method described in Example 5, specific catalysts were prepared, the difference being that the concentration of the aqueous metal salt solution was different, resulting in different active metal component contents.

[0056] The two-stage nickel-based catalysts F, G, H, I, J, K, and L obtained in Examples 6-12.

[0057] The parameters of the nickel-based catalysts A, B, C, D, E, F, G, H, I, J, K, and L obtained in Examples 1-12 are shown in Table 1:

[0058] Table 1: One-stage nickel-based catalyst indicators

[0059]

[0060] Table 2: Two-stage nickel-based catalyst indicators

[0061]

[0062]

[0063] Example 13

[0064] This example provides a method for producing alkanes, with the following specific details:

[0065] A 200 mL isothermal bed hydrogenation reaction evaluation device was used to load the above-mentioned catalysts, so that the MTO / MTP byproduct C6+ fraction and hydrogen entered the hydrogenation one-stage and two-stage reactors: the one-stage reaction catalyst used the one-stage nickel-based catalyst A, the reaction temperature was 150°C, the reaction pressure was 2.4 MPa, the feed airspeed was 0.2 h -1 ; the two-stage reaction catalyst used the two-stage nickel-based catalyst E, the reaction temperature was 250°C, the reaction pressure was 2.4 MPa, the feed airspeed was 0.6 h -1The alkane product is obtained.

[0066] The alkane product obtained in Example 13 was tested and the alkane content was >99%.

[0067] Examples 14-22

[0068] Examples 14-22 are consistent with the method steps of Example 13, only the catalysts and process parameters are different, the hydrogenation effects under different reaction conditions using different catalysts are shown in Table 3:

[0069] Table 3: Two-stage hydrogenation process parameters for producing alkane and the obtained olefin content of Examples 13-22

[0070]

[0071] As can be seen from Table 3, using the nickel-based catalyst of the present application, the MTO / MTP reaction by-products can be converted into alkane and the alkane content in the product is all greater than 99%.

[0072] In summary, the MTO / MTP by-product raw material of the present application is rich in oxides, using the nickel-based catalyst and production method of the present application, without the need for pretreatment work such as separation of oxides of the raw material, the hydrogenation effect is remarkable. As can be seen from the examples of the present application, using the nickel-based catalyst and production method of the present application, without the need for pretreatment work such as separation of oxides of the raw material, the hydrogenation effect is remarkable, the saturated alkane content is >99%. The present application widens the use of MTO / MTP by-product raw materials through a two-stage hydrogenation process, and increases the method of obtaining alkane, and has a broad market application prospect.

[0073] Any numerical values recited herein include all values from the lower value and the upper value in between. For example, if a component is stated as having a value of 50-90, it is intended that all values between 50 and 90 are also expressly stated. For values which are not integers, it is intended that all values between the lower and upper values are also expressly stated. It is also to be understood that the endpoints are provided as a typical range of values. There is no intention of excluding any other range of values or limits which are within the scope of the application. Numerical values are provided only as a specific example of the application. In this application, the use of "about" means that the value includes the stated value and also variations above and below the stated value.

[0074] It should be noted that the foregoing examples have been provided merely for the purposes of illustration and are not intended to limit the application in any way. Descriptions and examples of materials and processes of the application are intended to be illustrative not limiting. Any modifications of the application and other applications of the application will occur to those skilled in the art to which the application pertains and many options for modification of the application will suggest themselves. The application lies in the broadest aspects of the art, and there are many alternatives for carrying out the application. Accordingly, the scope of the application should be determined not with reference to the above description but with reference to the claims that follow.

Claims

1. A method for producing alkanes, characterized in that: MTO and / or MTP by-product C6 + The fraction is used as the raw material to produce alkanes under the action of nickel catalyst system without the need to separate the oxides of the raw material; The nickel-based catalyst system includes a first-stage catalyst and a second-stage catalyst; The one-stage catalyst comprises a one-stage composite support and an active component nickel supported on the one-stage composite support; The second-stage catalyst comprises a second-stage composite carrier and active components of molybdenum, cobalt and nickel supported on the second-stage composite carrier; The first-stage composite support and the second-stage composite support are each independently an Al2O3 / TiO2 composite support; The active component nickel in the first stage catalyst is in the form of nickel oxide and has a content of 12 to 18% based on the weight of the first stage catalyst; Based on the weight of the second-stage catalyst, the active component nickel in the second-stage catalyst is calculated in the form of nickel oxide, and the content is 2-5%; the active component molybdenum is calculated in the form of molybdenum oxide, and the content is 10-13%; the active component cobalt is calculated in the form of cobalt oxide, and the content is 1-4%; Make C6 containing MTO and / or MTP by-products + The feed of the fraction and hydrogen is contacted with the first stage catalyst to carry out a first stage reaction; + The feed of the distillate and hydrogen is contacted with the second-stage catalyst to carry out a second-stage reaction; The process conditions of catalytic hydrogenation are: the first stage reaction temperature is 150~200℃, the reaction pressure is 2.3~3.2MPa, the feed volume space velocity is 0.1~0.6h -1 The second stage reaction temperature is 220~280℃, the reaction pressure is 2.3~3.2MPa, and the feed volume space velocity is 0.6~1.5h -1 .

2. The method for producing alkanes according to claim 1, wherein Based on the weight of the first-stage catalyst, the content of nickel as an active component in the first-stage catalyst is 14-17% in the form of nickel oxide.

3. The method for producing alkanes according to claim 1, wherein Based on the weight of the second-stage catalyst, the active component nickel in the second-stage catalyst is calculated in the form of nickel oxide, with a content of 3-4%; the active component molybdenum is calculated in the form of molybdenum oxide, with a content of 11-12%; and the active component cobalt is calculated in the form of cobalt oxide, with a content of 2-3%.

4. The method for producing alkanes according to any one of claims 1 to 3, characterized in that In the first-stage composite support and the second-stage composite support, the weight ratio of TiO2 to Al2O3 is 1:(4~6) independently.

5. The method for producing alkanes according to any one of claims 1 to 3, characterized in that The composite carrier is in the shape of a clover, a strip or a cylinder.

6. The method for producing alkanes according to any one of claims 1 to 3, characterized in that The preparation method of the nickel-based catalyst system comprises the following steps: impregnating the metal active component nickel on a first-stage composite carrier to obtain a first-stage catalyst; and impregnating the metal active components molybdenum, cobalt and nickel on a second-stage composite carrier to obtain a second-stage catalyst.

7. The method for producing alkanes according to any one of claims 1 to 3, characterized in that The process conditions are as follows: a first-stage reaction temperature of 160-180°C, a reaction pressure of 2.5-2.9 MPa, and a feed volume space velocity of 0.3-0.5 h -1 and / or the second stage reaction temperature is 230~260℃, the reaction pressure is 2.5~2.9MPa, and the feed volume space velocity is 0.8~1.2h -1 .

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