Process Simulation Of The Synthesis Of Benzaldehyde By Toluene Through Oxidation, Esterification And Hydrogenation

Reactions, such as oxidation, hydrogenation and esterification play important roles in numerous processes which could not only extend the chain of the molecules, but also improve the value of the products. It was reported that there are about 25% of industrial catalysis processes are conducted through oxidation. Selective oxidation reactions are always exothermal processes. However, there are lots of thermodynamically instable chemicals being produced during these processes, resulting in low utilization of the feed and the formation of CO2, H2 O due to extensive oxidation of hydrocarbons. The selectivity of oxidation remains a challenge in these fields. In this these, the combination of oxidation, hydrogenation and esterification of toluene has been proposed to synthesize the benzaldehyde by an advanced software of Aspen Plus.The oxidation of toluene and its coresponding separation process were designed and simulated by Aspen Plus. The oxidation of toluene by air in liquid phase was carried out in column reactor for 4 hours. Results showed that the selectivity of benzonic acid was up to 95 % and 30 % conversion were observed at 150 oC, 0.5 MPa pressure. The separation process of oxidation of crude products showed that the unreacted toluene could be recovred by atmospheric pressure disti1 lation process, and the purity of recovered benzaldehyde could be achieved up to 99.9%.The esterification of benzoic acid using heteropoly acid as catalyst was carried out in esterification tower for 2 hours, with the mole ratio was 4:1 for methanol to benzoic acid, and about 100 % selectivity to methyl benzoate and 99.5 % conversion were realized at 180 oC, 2MPa pressure condition. The separation process of methanol and water was designed and simulated, results showed that the separation of unreacted methanol could be achieved by atmospheric pressure disti1 lation process, and the purity of recovered methanol could be achieved up to 99.9%.The hydrogenation of methyl benzoate was carried out in fixed bed reactor. The mole ratio was 50:1 for hydrogen to methyl benzoate, 80% selectivity to benzaldehyde and 80 % conversion were obtained at 260 oC, 1.5-2.0MPa pressure condition. The synthesis and separation process was designed and simulated. Results show that the circulating hydrogen flow could be converged in the processXand the by-products(i.e., benzyl ether) could be separated through the process, and 99.3% purity of benzaldehyde products could be achieved in the side-stream of distillation tower.