Preparation method of 1,1-difluoro ethane and its production equipment

Abstract

A process for preparing 1,1-bifluoroethane features that the initial lever of hydrofluoric acid is 60-70% of reactor's volume, the weight of catalyst is 30-40% of the weight of hydrofluoric acid, the feeding speed of acetylene is 0.08-0.12 kg/h for each kg of hydrofluoric acid, and the reaction temp and presure are 22-32 deg.C and 0.03-0.3 MPa. Its productive equipment is also disclosed, which features small ratio of length to diameter, full reaction, and less consumption of raw material.

Description

technical field [0001] The invention relates to a method for preparing 1.1 difluoroethane and its production equipment. Suitable for refrigerant production industry. Background technique [0002] 1.1 Difluoroethane (CH 3 CHF 2 ) The current international common name is HFC-152a, which is a widely used fluorine-containing organic compound, which can be used as a refrigerant, spray and raw material for the production of fluoroplastics, especially its ozone depletion potential (ODP) is 0, The global warming potential (GWP) is 0.02, therefore, it is receiving more and more attention as a substitute of CFC. 1.1 The conventional production process of difluoroethane is to use acetylene as a raw material, and react with hydrofluoric acid under the action of catalysts such as boron trifluoride, fluorosulfonic acid, and antimony pentafluoride. The reaction formula is as follows : [0003] <chemistry num="001"> <chem file="200410015662_cml001.xml" / > < / chemistry&...

AI Technical Summary

Problems solved by technology

[0008] The weak point of above-mentioned production technique is: 1) in order to improve the conversion rate of reaction as far as possible, the aspect ratio of reactor is often greater than 4, is a kind of long and narrow reactor

The proportions of fluorosulfonic acid and antimony pentafluoride used as catalysts are much larger than the raw material hydrofluoric acid. The specific gravity of hydrofluoric acid is 1.15, that of fluorosulfonic acid is 1.74, and that of antimony pentafluoride is 2.34. The catalyst often sinks The bottom of the reactor can only play a catalytic role in a small range, and the conversion rate of the direct reaction of acetylene and hydrofluoric acid is low (about 30-40%), so the utilization rate of the catalyst in the production process is low , so that the reaction cycle is short, the unit consumption is high, and the discharge of residual liquid is large

2) The influence of temperature, the reaction between acetylene and hydrofluoric acid is an exothermic reaction, and the heat released is also changing with the change of the reaction speed. The heat release is large in the pre-reaction stage, no heating is required, but cooling is required; Heating is required in the post-reaction stage, so temperature control is difficult

If the reaction temperature is low, the reaction speed will be slow and the production capacity of the device will decrease. If the temperature is high, the catalyst will fail quickly, high boiling by-products will increase, and the consumption of raw materials will increase. Both are not conducive to production.

3) The influence of pressure, acetylene is a highly chemically active substance, which will undergo self-polymerization under certain conditions. When the pressure in the reactor is high, the density of acetylene will increase relatively, and dimerization, three Polymerization and the generation of corresponding fluorides (high boilers), increase the unit consumption, and also increase the viscosity of the material in the reactor, which is unfavorable for the reaction; if the reaction pressure is low, it will affect the reaction speed and reduce the production capacity of the device. decline

4) The influence of the liquid level, because the reaction is continuous, hydrofluoric acid adopts the method of supplementing, and the second block is then continuously added, and the product is continuously removed from the top, and the liquid level in the reactor is also correspondingly reduced. At this time , the density of acetylene block in the liquid phase is increasing (when other conditions remain unchanged), therefore, the high boiling matter will increase, which is unfavorable for production

5) In the whole reaction, it is not convenient to add the catalyst, let alone discharge the residual liquid, the reaction process cannot be adjusted, and when the reaction is over, the residue in the reactor is discharged from the bottom at one time

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