Study On The Technology Of Photochlorination Of Acetic Acid In The Distillation Column With A Single Reactor

Monochloroacetic acid (MCA) is a rather important chemical raw material and organic intermediate product, which is mainly manufactured by chloride of acetic acid using sulfur and anhydride acetic acid as catalyst. The effort has been made in this paper to exploit a clean technology of MCA preparation by chlorination of acetic acid, using light as the initiating agent.The result of study on the apparent kinetics of photochlorination of acetic acid showed that the reaction rate is comparatively slow and the byproduct of dichloroacetic acid (DCA) is created during the reaction. In order to put the technology of photochlorination of acetic acid into industrialization, the new technology about distillation column with a single reactor having a large reactive potency must be adapted. The presumption that new technology about distillation column with a single reactor can be used in photochlorination of acetic acid is first proposed in this paper. The fact that reaction distillation has obvious advantages in the number of theoretically perfect trays and energy consumption was obtained by theoretical analysis between the coupling of reaction and distillation and the independent operation, which lays a theoretical foundation on the application of the distillation column with a single reactor in photochlorination of acetic acid.The distillation column with a single photochlorination reactor was built in this paper, which is used in the laboratory study. In light initiation, the semi-continuous operation was applied to study the influence of the chlorine flow, the reflux and the height of the packing on photochlorination of acetic acid. Crude MCA with a purity of 90% or more was attained and the feasibility of this technology was proved. It was showed that the influence of the chlorine flow on the selectivity of MCA was notable and the conditions affecting the separate ability such as the reflux and the height of packing could meet the demand of the restraining of the over-chlorination of MCA in the experimental conditions. As a result, restraining direct chlorination of acetic acid to DCA is necessary to improve the selectivity of MCA.In the distillation column with a single reactor, the outer loop reactor is designed and applied. The reaction dynamics datas of photochlorination of acetic acid in the reactor were tested. According to parallel-consecutive reaction dynamics model, the parameters were fitted and the model result tallys experiment result well. The fitted dynamics model parameters are as following:In order to apply the reaction distillation technology in more fields, the methylbenzene side-chain photo-chlorination has been done in the experiment apparatus. The results have proven this technology is feasible and crude benzyl chloride with a purity of 96~98% can be obtained.