A chromium-based catalyst and its application in the cis-trans isomerization reaction of olefins

Abstract

The present invention discloses a chromium-based catalyst and its application in the cis-trans isomerization reaction of olefins. The chromium-based catalyst comprises a chromium oxide composition. By mass percentage, the chromium oxide composition comprises 5-60% of Cr(OH) 3 , 30-70% of CrOOH and 5-30% of Cr 2 O 3 . When the chromium-based catalyst is used in the cis-trans isomerization reaction of olefins, especially in the isomerization reaction of trans-olefins to cis-olefins, the conversion rate of raw materials and the selectivity of products can be improved simultaneously.

Description

Technical Field

[0001] The present invention relates to the preparation of cis-fluorochloroolefins, and particularly to a chromium-based catalyst containing a chromium oxide composition with a specific mass distribution and its application in the cis-trans isomerization reaction of olefins. Background Art

[0002] The boiling point of Z-HCFO-1233zd (cis-1-chloro-3,3,3-trifluoropropene) is 40°C, it is non-flammable, has an ODP value of 0, a GWP value of less than 7, and an atmospheric residence time of 26 days. It is considered as a fourth-generation new blowing agent to replace HFC-245fa, and its application in refrigeration has also attracted wide attention. Among various synthesis routes of Z-1233zd, the route of using E-1233zd as raw material and obtaining Z-1233zd through a one-step cis-trans isomerization reaction has the advantages of easy availability of raw materials, simple process, and easy separation of products.

[0003] Patent CN102245548A discloses a method for converting E-1233zd to Z-1233zd under the action of a granular fluorinated Cr 2 O 3 、Cr 2 O 3 、AlF 3 catalyst. The reaction temperature is 250°C, the purity of raw material E-1233zd is 99.9%, the feeding rate is 0.8 lb / h, and after reacting for 10 h, the conversion rate of the raw material is about 9%, and the selectivity of Z-1233zd is about 90%.

[0004] Patent CN111925273A discloses a method for preparing Z-1233zd from E-1233zd. The catalyst is at least one or several of aluminum fluoride chloride, aluminum fluoride oxychloride, magnesium fluoride chloride, magnesium fluoride oxychloride, chromium fluoride chloride, and chromium fluoride oxychloride. When the reaction temperature is 290°C, the contact time is 30 s, and the pressure is 0.32 MPa, the conversion rate of E-1233zd is 13.3%, the selectivity of Z-1233zd is 97.9%, and the selectivity of E-1234ze is 2%.

[0005] Therefore, for the current route of isomerizing E-1233zd to prepare Z-1233zd, the purity requirement for raw material E-1233zd is relatively high. Even at a reaction temperature of 290°C, the conversion rate of the raw material is only 13%, and the product selectivity is 97.9%. High conversion rate and selectivity cannot be obtained simultaneously. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a chromium-based catalyst for cis-trans isomerization of olefins. The chromium-based catalyst can significantly improve the conversion rate of raw materials while ensuring the selectivity of raw materials at a relatively low reaction temperature.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] A chromium-based catalyst, the chromium-based catalyst comprising a chromium oxide composition, and in terms of mass percentage, the chromium oxide composition comprises 5-60% of Cr(OH) 3 , 30-70% of CrOOH and 5-30% of Cr 2 O 3 .

[0009] Preferably, the chromium oxide composition comprises 20-30% of Cr(OH) 3 , 40-60% of CrOOH and 10-30% of Cr 2 O 3 .

[0010] More preferably, the chromium oxide composition comprises 22-28% of Cr(OH) 3 , 45-55% of CrOOH and 17-28% of Cr 2 O 3 .

[0011] Furthermore, the chromium-based catalyst further comprises a promoter composition, the promoter composition comprising a promoter oxide and / or a promoter hydroxide, and the promoter is selected from at least one of zinc, calcium, aluminum, magnesium, iron, nickel, lanthanum, cerium, zirconium, indium, gallium, vanadium, titanium, yttrium, praseodymium or palladium, and the molar ratio of chromium in the chromium oxide composition to the promoter in the promoter composition is 1:0.001-1:1.

[0012] Preferably, the promoter is selected from at least one of zinc, aluminum, nickel, and the molar ratio of chromium in the chromium oxide composition to the promoter in the promoter composition is 1:0.05-1:1.

[0013] Furthermore, the promoter composition comprises 50-60% of a promoter oxide and 40-50% of a promoter hydroxide.

[0014] In a specific embodiment, in terms of mass percentage, the promoter composition comprises 50-60% of ZnO and 40-50% of Zn(OH) 2 .

[0015] The chromium-based catalyst according to any one of the above of the present invention can be obtained by the following steps:

[0016] A1. Add ammonia water to the chromium salt solution and the promoter salt solution to carry out a precipitation reaction, stop feeding when the pH value of the slurry is ≈6-10, filter the slurry, and wash the filter cake with deionized water until it is neutral;

[0017] A2. The filter cake is dried at 80 - 120 °C and sieved into particles;

[0018] A3. The sieved particles are calcined.

[0019] In step A2, preferably particles of 1 - 3 mm are obtained after sieving.

[0020] In step A3, the calcination temperature is 150 - 400 °C, the calcination pressure is 0.01 - 1.0 Mpa, the calcination atmosphere is a mixture of an oxidizing gas and nitrogen, and the oxidizing gas accounts for 10 - 90% of the gas volume of the mixture. The oxidizing gas is selected from oxygen or chlorine. Preferably, the calcination temperature is 250 - 360 °C, the calcination pressure is 0.02 - 0.8 Mpa, and the oxidizing gas accounts for 20 - 80% of the gas volume of the mixture.

[0021] The chromium salt solution in the present invention is selected from soluble chromium salts, such as at least one of chromium nitrate, chromium chloride, chromium sulfate or chromium oxalate.

[0022] The promoter component salt solution in the present invention is selected from chlorides, nitrates or sulfates of the promoter component. Preferably, the promoter component salt solution is selected from chlorides or nitrates.

[0023] The present invention also provides the application of any of the above-mentioned chromium-based catalysts. In particular, the chromium-based catalyst is used for the cis-trans isomerization reaction of olefins.

[0024] Furthermore, the chromium-based catalyst is used for preparing Z-1233zd from E-1233zd, preparing Z-1234ze from E-1234ze, preparing Z-1225ye from E-1225ye, and preparing Z-1336mzz from E-1336mzz.

[0025] The present invention also provides a preparation method of Z-1233zd. Specifically, using any of the above-mentioned chromium-based catalysts, it is prepared by the cis-trans isomerization reaction of E-1233zd.

[0026] Furthermore, the preparation method is as follows: E-1233zd and nitrogen are introduced at a space velocity of 50 - 2000 h -1 -1, and the molar ratio of E-1233zd to nitrogen is (1 - 10):1, and the reaction temperature is 100 - 400 °C. Preferably, the space velocity is 80 - 1000 h -1 -1, the molar ratio of E-1233zd to nitrogen is (2 - 8):1, and the reaction temperature is 120 - 360 °C.

[0027] The E-1233zd is pure E-1233zd or E-1233zd containing 0.01-1.0% HFC-245fa. Using E-1233zd containing a small amount of HFC-245fa can greatly reduce the refining cost of E-1233zd.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] Through the study of different chromium forms in the chromium-based catalyst, the present invention proposes that under the composition of different chromium forms (Cr(OH) 3 , CrOOH and Cr 2 O 3 ), the surface of the catalyst has an appropriate ratio of Bronsted acid and Lewis acid, so that at a lower reaction temperature, the conversion rate of raw materials and the selectivity of products can be improved simultaneously. Description of the Drawings

[0030] Figure 1 It is the XPS peak fitting curve of the chromium-based catalyst Cat 6# prepared in the example of the present invention. Detailed Embodiments

[0031] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternative, improved and equivalent solutions that may be included within the scope of the claims.

[0032] Preparation Example 1

[0033] Dissolve 50 g of CrCl 3 ·6H 2 O and 0.8 g of Zn(NO 3 ) 2 ·6H 2 O in 200 mL of deionized water, and then slowly dropwise add ammonia water solution to adjust the pH value to 9. After the precipitation reaction is completed, filter the slurry, wash it repeatedly with deionized water. When the pH value of the filter cake is approximately 7, place the filter cake in a blast drying oven and dry it at 120 °C for 6 h. Screen the dried catalyst into particles of 1-3 mm. Take 20 mL of catalyst particles and pack them in a nickel alloy tube (19×2 mm) of a fixed bed reactor, and calcine them at 200 °C with 10 v% O 2 / N 2 (200 mL / min) for 14 h, and the pressure is 0.04 Mpa. The obtained chromium-based catalyst is denoted as cat 1#.

[0034] Preparation Examples 2-7

[0035] The operations of Preparation Examples 2 - 7 were the same as those of Preparation Example 1, except that: they were calcined at 240 °C, 280 °C, 320 °C, 360 °C, 400 °C, and 420 °C respectively with 10 v% O 2 / N 2 (200 mL / min) for 14 h, and the obtained chromium-based catalysts were denoted as cat 2#, cat 3#, cat 4#, cat 5#, cat 6#, and cat 7# respectively.

[0036] Preparation Example 8

[0037] Dissolve 50 g of CrCl 3 ·6H 2 O and 0.8 g of Zn(NO 3 ) 2 ·6H 2 O in 200 mL of deionized water, then slowly add ammonia water thereto to adjust the pH value to 9. After the precipitation reaction ends, filter the slurry, wash it repeatedly with deionized water. When the pH value of the filter cake is approximately 7, place the filter cake in a forced-air oven and dry it at 120 °C for 6 h. Screen the dried catalyst into particles of 1 - 3 mm, and respectively take 20 mL of the catalyst particles and pack them in a nickel alloy tube (19×2 mm) of a fixed-bed reactor. Calcinate them at 360 °C with 20 v% O 2 / N 2 (200 mL / min) for 14 h, and the obtained chromium-based catalyst is denoted as cat 8#.

[0038] Preparation Examples 9 - 11

[0039] The operations of Preparation Examples 9 - 11 were the same as those of Preparation Example 8, except that: they were calcined respectively under the calcination atmospheres of 40 v% O 2 / N 2 (200 mL / min), 60 v% O 2 / N 2 (200 mL / min), 80 v% O 2 / N 2 (200 mL / min), and the obtained chromium-based catalysts were denoted as cat 9#, cat 10#, and cat 11# respectively.

[0040] Preparation Example 12

[0041] Dissolve 50 g of CrCl 3 ·6H 2 O and 0.8 g of Zn(NO 3 ) 2 ·6H 2O is dissolved in 200 mL of deionized water, and then an ammonia aqueous solution is slowly added dropwise thereto. The pH value is adjusted to 9. After the precipitation reaction is completed, the slurry is filtered and washed repeatedly with deionized water. When the pH value of the filter cake is approximately 7, the filter cake is placed in a blast drying oven and dried at 120 - 150 °C for 6 h. The dried catalyst is sieved into particles of 1 - 3 mm. 20 mL of the catalyst particles are respectively filled into a nickel alloy tube (19×2 mm) of a fixed bed reactor and calcined at 360 °C with 60 v% O 2 / N 2 (200 mL / min) for 4 h. The obtained chromium-based catalyst is denoted as cat 12#.

[0042] Preparation Examples 13 - 15

[0043] The operations of Preparation Examples 13 - 15 are the same as those of Preparation Example 12, except that the calcination times are 8 h, 12 h, and 16 h respectively. The obtained chromium-based catalysts are respectively denoted as cat 13#, cat 14#, and cat 15#.

[0044] Preparation Example 16

[0045] Dissolve 50 g of CrCl 3 ·6H 2 O and 0.8 g of Zn(NO 3 ) 2 ·6H 2 O in 200 mL of deionized water, and then an ammonia aqueous solution is slowly added dropwise thereto. The pH value is adjusted to 9. After the precipitation reaction is completed, the slurry is filtered and washed repeatedly with deionized water. When the pH value of the filter cake is approximately 7, the filter cake is placed in a blast drying oven and dried at 120 °C for 6 h. The dried catalyst is sieved into particles of 1 - 3 mm. 20 mL of the catalyst particles are respectively filled into a nickel alloy tube (19×2 mm) of a fixed bed reactor. The system pressure is 0.1 Mpa, and it is calcined at 360 °C with 60 v% O 2 / N 2 (200 mL / min) for 12 h. The obtained chromium-based catalyst is denoted as cat16#.

[0046] Preparation Examples 17 - 18

[0047] The operations of Preparation Examples 17 - 18 are the same as those of Preparation Example 16, except that the calcination system pressures are 0.3 Mpa and 0.5 Mpa respectively. The obtained chromium-based catalysts are respectively denoted as cat 17# and cat 18#.

[0048] Comparative Preparation Example 1

[0049] Use 20 mL of purchased Cr 2 O 3 (specific surface area is 250 m 2(3 mm in particle size, 1 g), after loading into the reactor, it was dried to remove water at 150 °C with N 2 (200 mL / min) and denoted as Cat D1#.

[0050] The above-prepared chromium-based catalysts Cat 1# to Cat 18#, Cat D1# were characterized by XPS according to Cr2P, and the content distribution of different forms of chromium oxide on the surface of each catalyst is shown in Table 1 below:

[0051] Table 1. Content distribution table of chromium oxide on the surface of chromium-based catalysts

[0052]

[0053]

[0054] Example 1

[0055] This preparation example is about the application of the prepared chromium-based catalyst in the cis-trans isomerization of E-1233zd to prepare Z-1233zd.

[0056] At 240 °C, E-1233zd (73 mL / min) and N 2 (32 mL / min) were introduced. After the products at the reactor outlet were treated to remove water and acid, they were fed into a gas chromatograph for quantitative analysis. The gas analysis results are shown in Table 2 below:

[0057] Table 2. Reaction results of Z-1233zd preparation

[0058]

[0059] Example 2

[0060] This example is about the application of the prepared chromium-based catalyst in the cis-trans isomerization of E-1234ze to prepare Z-1234ze.

[0061] 20 mL each of the prepared cat1# to cat18#, Cat D1# were respectively loaded into a nickel alloy tube (19×2 mm) of a fixed-bed reactor. At 240 °C, E-1234ze (73 mL / min) and N 2 (32 mL / min) were introduced. After the products at the reactor outlet were treated to remove water and acid, they were fed into a gas chromatograph for quantitative analysis. The gas analysis results are shown in Table 3 below:

[0062] Table 3. Reaction results of Z-1234ze preparation

[0063]

Claims

1. Application of a chromium-based catalyst, characterized in that: The chromium-based catalyst comprises a chromium oxide composition. In terms of mass percentage, the chromium oxide composition comprises 5-60% of Cr(OH) 3 , 30-70% of CrOOH and 5-30% of Cr 2 O 3 , and the chromium-based catalyst is used for preparing Z-1233zd from E-1233zd, Z-1234ze from E-1234ze, Z-1225ye from E-1225ye, and Z-1336mzz from E-1336mzz.

2. The application of the chromium-based catalyst according to claim 1, characterized in that: The chromium oxide composition comprises 20 to 30% of Cr(OH) 3 , 40 to 60% of CrOOH and 10 to 30% of Cr 2 O 3 .

3. The application of the chromium-based catalyst according to claim 1, characterized in that: The chromium-based catalyst further comprises a promoter composition, the promoter composition comprises promoter oxides and / or promoter hydroxides, the promoter is selected from at least one of zinc, calcium, aluminum, magnesium, iron, nickel, lanthanum, cerium, zirconium, indium, gallium, vanadium, titanium, yttrium, praseodymium or palladium, and the molar ratio of chromium in the chromium oxide composition to the promoter in the promoter composition is 1:0.001 to 1:

1.

4. The application of the chromium-based catalyst according to claim 3, characterized in that: By mass percentage, the promoter composition comprises 50-60% of promoter oxides and 40-50% of promoter hydroxides.

5. The application of the chromium-based catalyst according to any one of claims 1-4, characterized in that: The chromium-based catalyst is obtained by the following steps: A1. Add ammonia water to the chromium salt solution and the promoter salt solution to carry out a precipitation reaction. Stop feeding when the pH value of the slurry is ≈6-10. Filter the slurry and wash the filter cake with deionized water until it is neutral. A2. Dry the filter cake at 80-120°C and screen it into particles. A3. Calcine the screened particles.

6. The application of the chromium-based catalyst according to claim 5, characterized in that: In step A3, the calcination temperature is 150-400°C, the calcination pressure is 0.01-1.0 MPa, the calcination atmosphere is a mixture of an oxidizing gas and nitrogen, and the oxidizing gas accounts for 0.1-50% of the gas volume of the mixture.

7. The application of the chromium-based catalyst according to claim 6, characterized in that: The oxidizing gas is selected from oxygen or chlorine.

8. A preparation method of Z-1233zd, which is prepared by the cis-trans isomerization reaction of E-1233zd, characterized in that: A chromium-based catalyst is used. The chromium-based catalyst includes a chromium oxide composition. In terms of mass percentage, the chromium oxide composition includes 5 to 60% of Cr(OH) 3 , 30 to 70% of CrOOH, and 5 to 30% of Cr 2 O 3 .

9. The preparation method of Z-1233zd according to claim 8, characterized in that: The preparation method is as follows: E-1233zd and nitrogen are introduced at a space velocity of 50 - 2000 h -1 , and the molar ratio of E-1233zd to nitrogen is (1 - 10):1, and the reaction temperature is 100 - 400 °C.

10. The preparation method of Z-1233zd according to claim 9, characterized in that: The E-1233zd is pure E-1233zd or E-1233zd containing 0.01-1.0% HFC-245fa.

Images