Low-temperature ultra-high activity and environmentally friendly catalyst for synthesis of trans-1,3,3,3-tetrafluoropropene by gas phase isomerization

Abstract

The invention discloses a low-temperature, ultra-high activity, environment-friendly catalyst for synthesizing E-type HFO-1234ze by gas-phase catalytic isomerization of Z-type HFO-1234ze and a preparation method thereof. It is to solve the environmental problems of traditional chromium-based catalysts. Extensive use of heavy metal chromium will cause a series of serious pollution and health problems, as well as the problems of poor low-temperature activity and short service life of existing isomerization catalysts. The catalyst disclosed by the present invention consists of M / MgF 2 , where the matrix MgF 2 It has a rutile phase and a nano-spherical structure with a specific surface area greater than 120m 2 / g, high stability MgF with excellent sintering resistance at 500°C 2 , the active component M is selected from Co 3+ 、Ni 2+ , Fe 3+ , Zn 2+ , La 3+ 、Al 3+ , Ga 3+ , Mn 4+ 、Cu 2+ one or more of them. The preparation of the catalyst comprises the following steps: (1) preparing a polyol solution containing a magnesium source and doped with metal ions, adding a fluorination reagent dropwise at 150-240°C to obtain a catalyst xerogel; (2) drying the xerogel at 300-240°C Calcined at 500°C, and finally fluorinated at 150-400°C to obtain a low-temperature ultra-high activity, environmentally friendly and high-performance catalyst.

Description

technical field [0001] The invention relates to a catalyst, in particular to a gas-phase catalyzed isomerization of cis-1,3,3,3-tetrafluoropropene to synthesize trans-1,3,3,3-tetrafluoropropene with low temperature, ultra-high activity and environmental protection catalyst. Background technique [0002] 1,1,1,3-tetrafluoropropene, referred to as HFO-1234ze, the molecular formula is CF 3 CH=CHF, non-toxic, non-flammable, ODP is zero, GWP is about 6. HFO-1234ze has two configurations: cis (Z type) and trans (E type), among which the physical and chemical properties of E type are close to those of HFC-134a. The synthesis of E-type HFO-1234ze has attracted extensive attention from the industry. [0003] So far, among the many known synthesis methods of HFO-1234ze, the gas-phase dehydrofluorination synthesis using 1,1,1,3,3-pentafluoropropane as a raw material has the characteristics of simple operation, high space-time yield, and easy scale-up. A route with the most industri...

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Problems solved by technology

[0004] The catalyst for gas-phase isomerization reaction reported above contains chromium. However, chromium is a heavy metal element, and a large amount of discharge will cause serious pollution to the ecological environment; especially hexavalent chromium is a highly toxic substance that poses a great threat to animal and human health.

In addition, the above-mentioned catalysts need to be used under high-temperature reaction conditions (>200°C) to obtain high reactivity during use, which not only consumes high energy, but also easily leads to carbon deposition, which leads to rapid deactivation of the catalyst, and has low industrial application value.

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