Application Research Of Catalytic Distillation Technology In The Alcohol Dehydration Reactions

Catalytic distillation is an important chemical engineering processintegration technology combining catalytic reaction and distillation separationprocesses. It has been receiving a growing attention and has also been wildlyused in industrial production for offering a great number of advantages such ashigh selectivity, high conversion, low energy consumption, low investment,etc. In this thesis, the application of catalytic distillation technology in thealcohol dehydration reactions taking the methanol dehydration betweenmolecules to dimethyl ether and tert-butanol intramolecular dehydration toisobutylene for example was researched.Firstly, the intrinsic kinetics of methanol dehydration to dimethyl etherover an ion exchange resin catalyst was determined in a fixed-bed reactor. Theintrinsic kinetic model was established on the basis of Eley-Rideal mechanism,in which the parameters were estimated by fitting the experimental data, andthe activation energy E_aof68.7kJ·mol^-1and the pre-exponential factor k₀of120.7m³·kgcat^-1·s^-1were obtained. Then the kinetic model was tested and thetest results show that the kinetic model established not only agrees with the experimental results well but also is highly reliable, which indicates that thekinetic model can be adopted in the further study.Secondly, a new process consisting of the combination of a fixed-bedreactor and a catalytic distillaiton column for the synthesis of dimethyl etherfrom the dehydration of methanol was proposed. On the basis of the intrinsickinetic equaiton of methanol dehydration obtained above, the equilibriumstage model was adopted to simulate the new process on the Aspen Plussimulation platform and the comparison among the new process, traditionalprocess as well as the process consisting of a single catalytic distillaitoncolumn was also made. It was found that the technology combining afixed-bed reactor and a catalytic distillaiton column is more promising withrespect to the heat duty needed per unit mass of product than other twoprocesses.Finally, a new process for the separation of high-purity isobutylene fromraffinate C4was proposed. The equilibrium stage model was adopted tosimulate the part of tert-butanol dehydration to isobutylene using a singlecatalytic distillation column of the process on the Aspen Plus simulationplatform, into which the intrinsic kinetics of tert-butanol dehydrationdetermined in the reference was input. And the comparison among the processproposed, the process consisting of the combination of a fixed-bed reactor anda catalytic distillaiton column and traditional process was made. It was foundpromising with respect to the equipment investment as well as the heat duty needed per unit mass of product when using a single catalytic distillationcolumn.