Propylene trimerization multi-active center catalyst and preparation method

Abstract

The present application relates to the field of catalysts, in particular to a kind of high-efficiency propylene trimerization multi-active center catalyst and its preparation method.The propylene trimerization multi-active center catalyst is composed of porous carrier and Lewis acid, wherein the Lewis acid is any two or more combinations in AlCl3, CuCl2, ZnCl2.The present application combines different kinds of Lewis acid with porous carrier together, and the multi-active center catalyst suitable for propylene trimerization is prepared by impregnation method.The results show that compared with single Lewis acid catalyst, the propylene conversion rate and the selectivity of trimerization product 1-nonene of the obtained catalyst are improved.The method has simple process flow, low raw material price and has the potential for large-scale preparation.

Description

Technical Field

[0001] This invention relates to the field of catalysts, specifically disclosing a propylene trimer multi-active-center catalyst and its preparation method. Background Technology

[0002] Propylene trimerization is an important route for the production of fine chemicals. Its trimer product, 1-nonene, can be used as a comonomer to produce high-end lubricating oils PAO and mPAO, and can also be used to make polyolefin elastomers POE. Therefore, 1-nonene has very high economic value.

[0003] Catalysts for propylene trimerization can be broadly classified into two types: solid base catalysts and solid acid catalysts. With increasing global environmental awareness and the development of green chemistry, environmentally friendly catalytic processes are receiving more and more attention. Solid acid catalysts possess numerous advantages, including high activity, high conversion rate, mild reaction conditions, and recyclability. Especially in the synthesis of fine chemicals, they enable continuous reaction processes, enhance equipment production capacity, and demonstrate increasingly significant advantages, making them a promising next-generation environmentally friendly catalytic material.

[0004] Although solid acid catalysts have advantages such as high propylene conversion and stable catalytic performance in the propylene trimerization to 1-nonene reaction, the low selectivity of 1-nonene still hinders the further development of solid acid catalysts in the field of large-scale propylene trimerization. Summary of the Invention

[0005] The technical solution adopted in this invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a multi-active-site catalyst, the method comprising the following steps:

[0007] S1: Weigh 2-4 parts by mass of Lewis acid and dissolve it in 80-120 parts by mass of water to prepare a solution, and impregnate 5-15 parts by mass of porous carrier.

[0008] The Lewis acid is any two or more of AlCl3, CuCl2, and ZnCl2;

[0009] The porous support is any one or a mixture of two or more of γ-Al2O3, ZIF-8, and ZIF-20;

[0010] S2: The impregnated porous carrier is naturally dried under inert gas protection to remove excess solvent and activate it.

[0011] Preferably, in step S1, the immersion temperature is -10℃ to 10℃.

[0012] Preferably, in step S1, the soaking time is not less than 60 minutes.

[0013] Preferably, the porous carrier is ZIF-20.

[0014] Preferably, in step S2, the inert gas is N2 or Ar.

[0015] Furthermore, the inert gas is N2.

[0016] In a second aspect, the present invention provides a multi-active-site catalyst prepared by the method described in the first aspect, wherein the catalyst is a synthetic catalyst consisting of a porous support and a mixed Lewis acid supported on the support.

[0017] Thirdly, the present invention provides the use of the multi-active-site catalyst described in the second aspect for catalyzing the trimerization reaction of propylene.

[0018] The beneficial effects of this invention are:

[0019] This invention innovatively combines different Lewis molecules with porous supports to prepare a multi-active-site catalyst suitable for propylene trimerization, thereby improving the selectivity and conversion rate of 1-nonene. Using the multi-active-site catalyst provided by this invention to catalyze the propylene trimerization reaction, the selectivity of 1-nonene is successfully improved while maintaining a high propylene conversion rate. The highly efficient multi-active-site catalyst of this invention can improve 1-nonene selectivity while ensuring a high propylene conversion rate, effectively increasing 1-nonene yield and reducing subsequent distillation and separation costs, thus possessing significant economic and social benefits. Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] The catalyst effectiveness was tested in the following examples and comparative examples using the following method: The tests were conducted in a fixed-bed reactor, where the reaction tube was a stainless steel tube with an outer diameter of 4 mm and an inner diameter of 2.5 mm. Propylene was used as the feed material. During catalyst evaluation, the temperature was raised to 150°C under propylene gas flow, and then the reactor pressure was increased to approximately 10.0 MPa using a feed pump, while maintaining a controlled space velocity. The reaction products were then depressurized and introduced into a gas chromatograph for online analysis of the reaction results (propylene conversion and 1-nonene selectivity).

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the following embodiments. It should be noted that this invention is not limited to the following embodiments.

[0023] In the following examples, the catalyst is named as follows: "Mass ratio of AlCl3:CuCl2:ZnCl2" - "Support used (γ-Al2O3, ZIF-8, ZIF-20)" - "Impregnation temperature" - "Protective gas type"; for example, if the catalyst preparation conditions are AlCl3:CuCl2:ZnCl2=1:1:1, the support is ZIF-20, the impregnation temperature is 5℃, and it is activated under nitrogen protection, then it is named "111-Z20-5-N2".

[0024] Example 1

[0025] Preparation of multi-active-site catalysts with different Lewis acids:

[0026] ① Weigh 3.0g of Lewis acid (mass ratio AlCl3:CuCl2:ZnCl2 = 1:1:1, 1:1:0, 0:1:1, 1:0:1) and prepare a solution with 100g of water. Impregnate the solution with 10.0g of ZIF-20 carrier at 5℃ for 60min.

[0027] ② Under nitrogen protection, the impregnated carrier is activated to remove excess solvent from the carrier, i.e., it is naturally dried under inert gas protection.

[0028] The catalytic results of the catalyst prepared by this method are shown in Table 1.

[0029] Table 1. Test results of the effects of each catalyst in Example 1

[0030]

[0031] Example 2

[0032] Preparation of multi-active-site catalysts with different porous supports:

[0033] The catalyst was prepared according to the synthesis method in Example 1, except that the ratio of the three Lewis acids AlCl3:CuCl2:ZnCl2 was fixed at 1:0:1, and the porous supports were selected as γ-Al2O3, ZIF-8, and ZIF-20, respectively.

[0034] The catalytic results of the catalyst prepared by this method are shown in Table 2.

[0035] Table 2. Test results of the effects of each catalyst in Example 2

[0036]

[0037] Example 3

[0038] Preparation of multi-active-site catalysts at different impregnation temperatures:

[0039] The catalyst was prepared according to the synthesis method in Example 1, except that the ratio of the three Lewis acids AlCl3:CuCl2:ZnCl2 was fixed at 1:0:1, and the impregnation temperatures were set to -10℃, 5℃ and 10℃, respectively.

[0040] The catalytic results of the catalyst prepared by this method are shown in Table 3.

[0041] Table 3. Test results of the effects of each catalyst in Example 3

[0042]

[0043] Example 4

[0044] Preparation of multi-active-site catalysts activated under different inert gases:

[0045] The catalyst was prepared according to the synthesis method in Example 1, except that the ratio of the three Lewis acids AlCl3:CuCl2:ZnCl2 was fixed at 1:0:1, and the inert gases were N2 and Ar, respectively.

[0046] The catalytic results of the catalyst prepared by this method are shown in Table 4.

[0047] Table 4. Test results of the effects of each catalyst in Example 4

[0048]

[0049] Comparative Example

[0050] The catalyst was prepared according to the method of Example 1, except that only a single Lewis acid was used to treat the porous support. 1-Nonene was prepared by propylene trimerization under the conditions of Example 1.

[0051] The catalytic results of the catalyst prepared by this method are shown in Table 4.

[0052] Table 5 shows the test results of the effects of each catalyst in the comparative examples.

[0053]

[0054] The test results above show that combining different Lewis acids and loading them onto a porous support can significantly improve the reaction conversion rate and the selectivity for 1-nonene.

Claims

1. The application of a multi-active-site catalyst in the catalytic trimerization reaction of propylene, characterized in that, The method for preparing the catalyst includes the following steps: S1: Weigh 2-4 parts by weight of Lewis acid and dissolve it in 80-120 parts by weight of water to prepare a solution, and impregnate 5-15 parts by weight of porous carrier. The Lewis acid is any two or more of AlCl3, CuCl2, and ZnCl2; the impregnation temperature is -10℃ to 10℃, and the impregnation time is not less than 60 min. The porous support is any one or a mixture of two or more of γ-Al2O3, ZIF-8, and ZIF-20; S2: The impregnated porous support is naturally dried under N2 or Ar protection in an N2 or Ar atmosphere to remove excess solvent and activate it.

2. The application of the multi-active-site catalyst according to claim 1 in the catalytic trimerization reaction of propylene, characterized in that, The porous carrier is ZIF-20.

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