| Cumene and meta-diisopropylbenzene are very important organic chemical raw materials. Cumene can mainly be used for the production of phenol, and m-DIPB is mainly oxidized to resorcinol. Recently, with the increasing need of phenol and resorcinol in industry, the need for cumene and m-DIPB are also increasing. Mixed isopropylbenzene (DIPB and TIPB) are the depth alkylation products in the synthesis of cumene with benzene and propylene. The transalkylation of mixed isopropylbenzene is an important constituent process for the production of cumene, which can improve the yield of cumene. In three isomers of DIPB, it is easy to separate p-DIPB, but o-DIPB and m-DIPB can not be separated easily. Therefore, the work of changing o-DIPB into m-DIPB by using environment friendly zeolite molecular sieve catalyst in isomerization reactions is valuable. But this work has not been reported in detail at home and abroad. In this paper, we respectively studied the reactions of mixed isopropylbenzene transalkylation and the isomerization of DIPB which is rich in o-DIPB. Finally, we discussed the separation process of m-DIPB.First, we investigated the transalkylation performance of modified (3 zeolite in mixed isopropylbenzene reaction. Results show that the modification by low concentration of citric acid and triethylamine can both improve the catalytic activity, and the catalytic effect of the former is better than the latter. The temperature has significant effects on the reaction. On A-1 catalyst, considering the variety of factors, the suitable reaction temperature is 205℃. At this temperature, the average conversion rates of DIPB,1,2,4-TIPB and TIPB are 80%,92% and 33% in 8h, but n-propylbenzene content is nearly 3000μg/g.Secondly, we inspected the isomerization of DIPB and found that A-1 catalyst shows high activity and stability. The optimum reaction temperature and feeding flow is 195℃and 12 ml/h at the pressure of 3.2 MPa by using 4 g catalyst. Under these conditions, the product content of o-DIPB and o-DIPB/m-DIPB (a) is about 0.5% and 1%, which can achieve later separation requirements. In the isomerization reaction, adding benzene can guarantee the catalyst activity and stability, reduce the content of the heavier components in the product, save energy and material consumptions, and can protect the environment. This process is more suitable for industrial production.Finally, we discussed the separation process of m-DIPB. Isomerization experiments results show that this reaction can effectively reduce the content of o-DIPB. We can obtain the desired target products by adjusting the reaction temperature and feed flow. It showed that shape-selective cracking reaction can effectively reduce p-DIPB content, but with a lot of side reactions. Direct cracking process is not feasible, which can lose a lot of m-DIPB and produce large amounts of light components. Adopting isomerization-cracking reaction process can achieve separation requirements, but the cost is high. Distillation experiments show that isomerization and isomerization-cracking reaction products can all be separated to meet the downsteam demand products (m-DIPB content more than 96%,p-DIPB content less than 2%). The latter yield (62.12%) is slightly higher than the former (51.53%), but the latter takes longer distillation. Considering various factors, we choose isomerization product distillation process to separate m-DIPB.
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