Method for continuously producing 1, 1, 2-trichloroethane

Abstract

The invention provides a method for continuously producing 1, 1, 2-trichloroethane, which comprises the steps of: adding 1, 2-dichloroethane and initiating agent into a stirring preheat kettle for preheating; leading the evaporated 1, 2-dichloroethane to condensate and backflow; feeding the mixed raw material liquid into a pre-reaction packed tower to have reaction with chlorine; carrying out condensation on the generated HCl, uncondensable gas and the evaporated 1, 2-dichloroethane; then, carrying out liquid phase backflow; leading product at the bottom of the pre-reaction packed tower to enter into a number of stirring absorption kettles which are connected in series; leading the chlorine to enter into the stirring absorption kettles to have reaction with the 1, 2-dichloroethane; carrying out condensation on the generated HCl, uncondensable gas, unreacted chlorine and the evaporated 1, 2-dichloroethane by a second condenser; then, carrying out liquid phase backflow; filling gas phase into the pre-reaction packed tower; and discharging the reaction product containing the 1, 1, 2-trichloroethane from an outlet; wherein n is integral number of 1-5. The method of the invention is suitable for industrialized-scale production and has low energy consumption.

Description

technical field [0001] The present invention relates to a process for producing 1,1,2-trichloroethane. Background technique [0002] 1,1,2-Trichloroethane is an important organic intermediate that can be used in the production of vinylidene chloride (VDC) monomer. The methods for industrialized preparation of 1,1,2-trichloroethane mainly include vinyl chloride (VCM) chlorination method and dichloroethane (EDC) chlorination method. Due to the mild conditions and mature technology of VCM chlorination method, domestic manufacturers Almost all adopt this route, and the relevant patents applied for include CN1440959A, CN1793093A, CN02127809.11, CN200510111981.8, etc. However, as the international oil price continues to rise in recent years, the production cost continues to rise. The cost advantage has become the trend of the times. The VCM chlorination method has been eliminated abroad and the EDC chlorination method has been replaced. For example, the patent US2174737 introduce...

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Problems solved by technology

The disadvantages of the above methods are that the selectivity of the reaction is poor, and there are many side reactions, which cause the difficulty of subsequent separation, and some equipment is very complicated, which is not suitable for large-scale industrial production.

[0003] The applicant's patent CN200510029868.5, on the basis of US patent US2621153, developed and perfected the process of producing 1,1,2-trichloroethane by reactive distillation under the condition of no catalyst, the operating condition is reaction pressure 0.1MPa, The heating temperature of the tower kettle is about 114°C, and higher conversion rate and selectivity are obtained, but the shortcomings of reactive distillation are also very obvious. Under certain conditions, there will be a large amount of unreacted 1,2-dichloroethane in the stripping section of the reactive distillation column into the gas phase. In order to reduce material loss, it needs to be cooled in the rectifying section, resulting in a large amount of energy consumption, and the processing capacity can only be maintained at a relatively low level. According to the examples in the patent, in a reactive distillation column with an effective height of 4 meters, the feed rate of 1,2-dichloroethane is only 0.15 kg / hour, although conversion rate and selectivity reach 96.2% and 93% respectively, its 1,1, the output of 2-trichloroethane also only has 0.18 kilogram / hour, if enlarged to industrial scale, the liquid holding capacity of reactive distillation column and energy consumption will be very large

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