Investigation of the Hβ Molecular Sieve Inactivation Caused by Reactants and Products and Improvement of Continuous Thiophene Acylation

In this paper, the factors leading to the inactivation of the molecular sieve are explored in the batch thiophene (TH) acylation. The coexistence of acetic anhydride (AC) as the reactant and 2-acetylthiophene (2-ATH) as the product plays a key role in accelerating the inactivation, attributing to the 2-ATH polymerization. According to the molecular simulation, when AC is not present, the energy barrier of 2-ATH polymerization can be reduced from 287.45 kJ/mol to 85.87 kJ/mol. Then, the process of the continuous TH acylation is improved, in which thiophene is excessive (molar ratio). After optimizing the molar ratio and volume flowrate of raw material, the productivity of the catalyst can reach 21.56 g/g, which exceeds the best process previously studied (15.10 g/g). Subsequently, the use of carbon tetrachloride (CT) as a solvent is further studied, hoping to further improve the performance of the catalyst, and a significant advancement is achieved, in which the production capacity of the catalyst exceeds 45 g, and the conversion rate of AC can still be as high as 96% after the reaction is carried out for 15,000 min.