Method for preparing fluorinated alkene by performing dehydrochlorination on chlorofluorocarbon under action of catalyst

A technology for dehydrochlorination and fluorine-containing olefins, which is applied in the direction of dehydrohalogenation preparation, chemical instruments and methods, physical/chemical process catalysts, etc., can solve the problems of short service life of catalysts, high production costs, low yields, etc., and achieve reduction Operating cost, low specification requirement, effect of increased selectivity

Active Publication Date: 2013-12-04
山东华安近代环保科技有限公司
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Problems solved by technology

[0005] Chinese patent (publication number: CN101772480) discloses a method of removing HCl by contacting HCFC-244bb with activated carbon at a certain temperature to obtain HFO-1234yf. The conversion rate can reach up to 80%, but there is no corresponding HFO-1234yf selective reporting
[0006] The above preparation method has high requirements on the purity of the raw material HCFC-244bb (generally, the purity of 244bb should be above 95%), while the raw material 2-chloro-1,1,1,2-tetrafluoropropane (abbreviated as HCFC-244bb) It is prepared by the addition of 2-chloro-3,3,3-trifluoropropene (abbreviated as HCFO-1233xf) and HF under the action of a catalyst, which makes the crude HCFC-244bb contain a large amount of HCFO-1233xf, HF and 1 , 1,1,2,3-pentafluoropropane (abbreviated as HFC-245eb) and other impurities, while HCFC-244bb and HCFO-1233xf have similar boiling points and form an azeotrope, which leads to the need for multiple rectification operations in ordinary distillation operations. Realization, which increases the production cost of the process
More importantly, these impurity components will seriously affect the catalyst life and product selectivity of the dehydrochlorination reaction in the above patents, resulting in short catalyst life, high energy consumption, low yield, and high production costs

Method used

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  • Method for preparing fluorinated alkene by performing dehydrochlorination on chlorofluorocarbon under action of catalyst
  • Method for preparing fluorinated alkene by performing dehydrochlorination on chlorofluorocarbon under action of catalyst
  • Method for preparing fluorinated alkene by performing dehydrochlorination on chlorofluorocarbon under action of catalyst

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] Embodiment 1: adopt impregnation method to prepare catalyst

[0044] (1) 11.0g magnesium nitrate (Mg(NO 3 ) 2 ), 24.0g ytterbium nitrate (Y 2 (NO 3 ) 3 ), 10.0g ferric chloride was dissolved in 80ml distilled water to make a solution, and then the specific surface area was 860m 2 / g of coal-based activated carbon is added to the above solution as a carrier, after immersion for 8 hours, it is dried at 120°C for more than 12 hours, and then the precursor is roasted in a muffle furnace at 400°C for 6 hours to obtain a catalyst. The mass percentage is : 5%wt.Mg-1.5%wt.Y-3.0%wt.Fe / AC, spare.

[0045] (2) The preparation process of the catalyst is basically the same as (1), except that the magnesium nitrate is changed to cesium chloride, the ytterbium nitrate is changed to aluminum sulfate, the ferric chloride is changed to lanthanum nitrate, the immersion time is changed to 6h, and the drying temperature is Change it to 80°C, change the calcination temperature to 450°C...

Embodiment 2

[0067] A series of catalysts prepared by the examples are used as dehydrochlorination catalysts, and 60ml of catalysts are loaded into a fixed-bed tubular reactor with a diameter of Φ38mm. At a reaction temperature of 350°C to 850°C, 2 -Mixture of chloro-1,1,1,2-tetrafluoropropane, 15wt.% of 2-chloro-3,3,3-trifluoropropene and 5wt.% of HF, through the catalyst bed, the residence time is 18s . The product is washed with water and alkali to remove HCl and HF, and then analyzed by gas chromatography. The analysis method is the area normalization method. Before the reaction, the catalyst was kept at 400°C for 2 hours in a hydrogen atmosphere, then adjusted to the reaction temperature, and the reaction raw materials were switched, and the reaction was carried out for 10 hours. The reaction results are shown in Table 1.

[0068] The reaction result of table 1 embodiment 2

[0069]

[0070] It can be seen from Table 1 that increasing the reaction temperature can effectively incr...

Embodiment 3

[0072] This example uses the same operating conditions as in Example 2, except that the composition of the reaction raw materials is changed to 85wt.% of 2-chloro-1,1,1,2-tetrafluoropropane, 10wt.% of 2-chloro - The mixture of 3,3,3-trifluoropropene and 5wt.% HF, the contact time was changed to 0.5s, 18s, 33s and 60s, the reaction results are shown in Table 2.

[0073] The reaction result of table 2 embodiment 3

[0074]

[0075] It can be seen from Table 2 that prolonging the reaction contact time can significantly increase the conversion of raw materials, but will partially reduce the selectivity of the target product.

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Abstract

The invention belongs to the field of refrigerant, and provides a method for preparing fluorinated alkene by performing dehydrochlorination on chlorofluorocarbon under the action of a catalyst.According to the invention, the novel catalyst is prepared through an impregnation method, reaction of the catalyst and 2-chloro-l, 1, 2-tetrafluoro propane (HCFC-244bb) with lower purity is performed, and then high-temperature gas phase dehydrochlorination reaction is performed to prepare a fluorinated alkene product 2, 3, 3, 3-tetrafluoro propene. Through the adoption of the novel catalyst, the purity requirement on chlorofluoropropane is reduced, so that HCFC-244bb with the purity of 80 percent can be as a raw material, thereby effectively reducing the operating cost of the process; the halohydrocarbon conversion rate is high, and reach up to 60 percent, and the selectivity of the target fluorinated alkene is greater than 90 percent.

Description

technical field [0001] The invention belongs to the field of refrigerants and relates to a fluorine-containing olefin, in particular to a method for preparing fluorine-containing olefin by catalytic dehydrochlorination of chlorofluoroalkane. Background technique [0002] Hydrofluorocarbons (HFCs) are a class of compounds that are currently widely used as refrigerants. However, it has been found that such compounds have a high global warming potential (GWP), and a large amount of emission will cause global warming and aggravate the global greenhouse effect. It has been listed as one of the greenhouse gases by the Kyoto Protocol. For this reason, the world is actively looking for its environmentally friendly alternatives. Fluorine-containing olefins, especially hydrofluoroolefins (hydrofluoroolefins, HFO), such as 2,3,3,3-tetrafluoropropene (abbreviated as HFO-1234yf), are new types of olefins with zero ozone depletion potential (ODP) and low GWP value. Organic fluorides hav...

Claims

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Application Information

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IPC IPC(8): C07C21/18C07C17/25B01J23/83B01J23/10B01J23/78B01J23/86B01J23/26
Inventor 吕剑毛伟王博郝志军杜咏梅秦越杨志强马辉
Owner 山东华安近代环保科技有限公司
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