Progress in alkylation of gasoline with molecular sieve catalyst for benzene reduction

With the increasing awareness of environmental protection, the limitation of benzene content in gasoline is becoming more and more stringent. Benzene reduction technologies of gasoline mainly include saturation by hydrogenation, distillation, etherification and alkylation, among which alkylation technology has obvious advantages in improving the octane number and yield of gasoline. The process and reaction mechanism of alkylation with methanol and light hydrocarbons as alkylation reagents, which are widely used at present, are reviewed. The structure and characteristics of typical molecular sieves ZSM-5, MCM-22 and Beta, and their catalytic alkylation characteristics are analyzed in detail. It is pointed out that methanol, when used as an alkylation reagent, needs higher reaction temperature than the light hydrocarbons with high carbon number, but has less influence on the distillation range of gasoline. When light hydrocarbon is used as alkylation reagent, the activation temperature decreases with the increase of carbon number, but it has a great impact on the distillation range of gasoline, and the deactivation of molecular sieves would take place by their promotion of olefin polymerization at low temperature. At present, the application of the three kinds of molecular sieves is difficult to balance the benzene conversion, gasoline distillation range and energy consumption. The development of molecular sieves with suitable pore size, the preparation of composite molecular sieves and hierarchical porous molecular sieves are expected to solve this problem. © 2023 Chemical Industry Press. All rights reserved.