Process and apparatus for preparation of ethylbenzene by alkylation of benzene with dilute ethylene contained in dry gas by catalytic distillation

A process for preparation of ethylbenzene by alkylation of benzene with dilute ethylene contained in dry gas by catalytic distillation, which is carried out within a catalytic distillation tower comprising a reboiler, a stripping section, a reaction section, an optional rectifying section, and a top condenser;

• characterized in that
• 1) pre-treating the dry gas from refinery by, if necessary, pressure adjusting, desulfurization and dehydration, resulting in a pre-treated dry gas;
• 2) Feeding the pre-treated dry gas into a catalytic distillation tower at a position below the reaction reaction, and feeding benzene into the tower at its top, or splitting benzene feed to several streams and feeding them into the tower at its top and at different positions of the reaction section;
• With the total molar ratio of benzene to ethylene being in the range of 5-20, keeping the two feeds countercurrently flowing in the tower and reacting with each other inside the reaction section which is packed with catalyst particles/distillation packing, and separating the mixture of reactants and products by distillation simultaneously;
• Drawing the top overhead and the bottoms comprising product ethylbenzene out of the tower respectively;
• 3) The reaction section packed with catalyst particles and distillation packing should meet the following conditions:
• (a) The catalyst used satisfies:
• evaluated ethylene conversion≧95%, and
• evaluated ethylbenzene selectivity≧95;
• (b) The separating efficiency of the reaction section satisfies:
• ≧0.5 theoretical stage per meter of measuring tower (catalyst particles+ distillation packing)
• (c) The bed voidage of the reaction section is ≧70%.