Study On The Purification Of M-Dichlorobenzene

The demand of m-dichlorobenzene is increasing rapidly for its widely applications in the synthesis of pesticides and so on. Since the physical properties of the dichlorobenzene isomers are similar, the purification of m-dichlorobenzene from the mixture has has attracted much attention. Here, the study focused on the purification of m-dichlorobenzene from the mixture (m-dichlorobenzene/p-dichlorobenzene with the weight ratio of 85:15) by combining the complexing separation and adsorption separation technology. The reaction conditions which affect the yield and purity of m-dichlorobenzene have been investigated, the optimized conditions are as follows:PEG6000, PEG:p-dichlorobenzene=1:1(wt); the reaction time:5 minutes, temperature:45℃; the cooling time:30 minutes, temperature:4℃; stiring in the whole process. The complex compound is vacuum distillation for the recycle of PEG and dichlorobenzene mixture. The adsorption isotherm of p-dichlorobenzene which adsorbed on the molecular sieve, can fit the langmuir adsorption isotherm well at 20℃. Different temperatures and mass space velocities have elected to investigate the effect of the result. Under 20℃and the space velocity is 2.3g/(h·g), the weight of the product at the percent of 99%is 4.75 times as the molecular sieve and 7.25 times at 99.5%.