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Mesoporous chromium-oxide-based catalyst for dehydrohalogenation reaction

A chromium-based catalyst, dehydrohalogenation technology, applied in the direction of dehydrohalogenation preparation, physical/chemical process catalyst, metal/metal oxide/metal hydroxide catalyst, etc., can solve poor thermal stability, component loss, specific Small surface area and other issues, to achieve the effect of rich mesoporous structure, high stability and large specific surface area

Active Publication Date: 2015-04-01
XIAN MODERN CHEM RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The above-mentioned chromium oxide-based catalysts for dehydrohalogenation have the problems of small specific surface area, narrow pore size, and poor thermal stability.
More importantly, the above-mentioned low specific surface area, non-porous or narrow-pore structure makes the active sites of the chromium oxide catalyst highly concentrated on the outer surface of the catalyst, resulting in the reaction activity being easily caused by catalyst surface carbon, component loss, crystal phase transition, grain It grows up and declines rapidly, making it difficult to prepare fluorine-containing olefins for a long time

Method used

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  • Mesoporous chromium-oxide-based catalyst for dehydrohalogenation reaction
  • Mesoporous chromium-oxide-based catalyst for dehydrohalogenation reaction
  • Mesoporous chromium-oxide-based catalyst for dehydrohalogenation reaction

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0060] Example 1: Preparation of mesoporous chromium oxide by template method

[0061] Dissolve a mixture of 10.0g trivalent chromium soluble salt, 30.0g urea, 15.0g templating agent and 20.0g ionic strength regulator in water, and reflux at 100°C for 9 hours with stirring to allow it to fully precipitate, and then suction-filter to obtain a precipitated solid , washed with deionized water until neutral, and then dried overnight at 100 °C to obtain a mesoporous chromium oxide precursor. Then the body was roasted in a muffle furnace for 8 hours to obtain mesoporous chromium oxide.

[0062] Catalyst N 2 Adsorption and desorption performance test: the chromium oxides prepared under different chromium soluble salts, template agents, ionic strength regulators and roasting temperatures and their specific surface areas and pore size distributions are shown in Table 1, wherein the isothermal The adsorption-desorption curve is as figure 1 shown.

[0063] Catalyst physicochemical pr...

Embodiment 2

[0067] Dissolve 8.0g of fluorides corresponding to alkali metals Na, K, Rb, and Cs in 100ml of distilled water to make a solution, and then add 2 / g of mesoporous chromium oxide, impregnated for 6 hours, dried at 80°C for more than 12 hours, and then roasted the precursor in a muffle furnace at 400°C for 6 hours to obtain a chromium oxide-based dehydrohalogenation catalyst.

[0068] A series of alkali metal-doped chromium oxide catalysts prepared as dehydrochlorination catalysts were filled with 60ml of catalysts in a fixed-bed tubular reactor with a diameter of Φ38mm. At a reaction temperature of 400°C, 2-chloro- 1,1,1,2-Tetrafluoropropane passed through the catalyst bed with a residence time of 24s. 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. After 48 hours of reaction, the results of dehydrochlorination are shown in Table 2.

[0069] The reaction result of ...

Embodiment 3

[0073] Dissolve 10.0g of the corresponding nitrates of alkaline earth metals Mg, Ca, and Ba in 100ml of distilled water to make a solution, and then add 2 / g of mesoporous chromium oxide, impregnated for 6 hours, dried at 100°C for more than 12 hours, and then roasted the precursor in a muffle furnace at 500°C for 6 hours to obtain a chromium oxide-based dehydrohalogenation catalyst.

[0074] A series of alkaline earth metal-doped chromium oxide catalysts were prepared as dehydrochlorination catalysts, and 60ml of catalysts were loaded into a fixed-bed tubular reactor with a diameter of Φ38mm. At a reaction temperature of 400°C, 2,3- Dichloro-1,1,1-trifluoropropane passed through the catalyst bed with a residence time of 24s. 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. After reacting for 48 hours, the results of dehydrochlorination are shown in Table 3.

[007...

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Abstract

The invention discloses a mesoporous chromium-oxide-based catalyst for dehydrohalogenation reaction and a preparation method of the mesoporous chromium-oxide-based catalyst, and aims at solving the problems of small specific surface area, narrow porous structure and the like in preparation of the chromium-oxide-based catalyst. The preparation method comprises the following steps: (1) preparing an aqueous solution containing chromium salt, a pH regulating agent, a template agent and an ion-strength regulating agent, flowing back at the temperature of 100 DEG C, roasting under the condition of 350-500 DEG C so as to obtain a mesoporous chromium-oxide base body; and (2) dipping the aqueous solution doped with components into the chromium-oxide base body obtained in the step (1) and finally roasting at the temperature of 400-550 DEG C to prepare the catalyst. The mesoporous chromium-oxide-based catalyst disclosed by the invention can be used for achieving the high-efficiency dehydrohalogenation reaction of fluorochloroalkylene.

Description

technical field [0001] The invention relates to a dehydrohalogenation catalyst, in particular to a mesoporous chromium oxide-based catalyst used for preparing fluorine-containing olefins from chlorofluoroalkanes under gas phase conditions and a preparation method thereof. Background technique [0002] Fluorine-containing olefins, especially hydrofluoroolefins (hydrofluoroolefin, HFO), such as 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,3,3,3-tetrafluoropropene (HFO-1234ze), Trifluoroethylene (HFO-123a) is a new type of organic fluoride with zero ozone depletion potential (ODP) and low GWP value. Uses such as plastic monomers. [0003] Gas-phase catalytic dehydrohalogenation of chlorofluoroalkanes is a major method for the preparation of fluorinated alkenes. Such as 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) dehydrochlorination to generate HFO-1234yf, 1,1,1,3,3-pentafluoropropane (HFC-245fa) dehydrofluorination to generate HFO -1234ze. [0004] US Patent No. 7,560,60...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J23/26B01J23/86B01J35/10C07C17/25C07C21/18
Inventor 毛伟吕剑王博亢建平郝志军秦越杨志强王伟张伟何飞
Owner XIAN MODERN CHEM RES INST
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