Research On A Fixed Bed Reactor Of Alkylation Of Toluene With Methanol

Paraxylebe is an extremely important chemical raw materials. In addition to medicine, solvents and pesticides having a certain demand for PX, the rest are mainly used in the polyester industry. Along the rapid development of the polyester industry, China was caused in a high degree of dependence on imports, so PX production capacity was needed to be improved urgently. As a new technical route for the preparation of PX, the alkylation of toluene with methanol is environmentally-friendly and can meet the requirements of domestic development.On the basis of existing intrinsic kinetics, the one-dimensional and two-dimensional fixed-bed reactor models were established under the condition that the influence of internal diffusion on the reaction process was fully considered. Meanwhile the distribution of the conversion rate, yield, temperature and pressure for each material in the catalyst bed also could be gotten. The simulation results show that the toluene conversion and temperature increased with the increasing catalyst bed and the two indexes were slowed down around 0.8m. Finally, the toluene conversion was about 25% and the adiabatic temperature rise was 44.5?. The reaction mainly occurred in the early stage of the fixed bed and the reaction heat was released in a short time which put the temperature rising rapidly. Due to the existence of radial diffusion and large heat transfer coefficient, there was no obvious concentration and temperature difference in the radial direction of the two-dimensional model.The experimental data was in good agreement with the simulation results and the toluene conversion rate was 5% higher than that of the methanol non-segmented process. After confirming the validity of the methanol feedstocks, ASPEN software was used to simulate the multi-stage methanol feedstocks to find the optimal number of methanol segments and the methanol ratio. It was proved that methanol three segmented feedstocks was the best, under these conditions of the first ratio of 0.4-0.5 and the second split ratio of 0.4-0.5, the conversion of toluene was up to 34%.