An alkylating agent alkylates an alkylation substrate in a solid catalyst alkylation process in which an alkylation reactor produces a reaction effluent and a catalyst regeneration zone produces a hydrogen-containing regeneration effluent.

This invention is particularly applicable to alkylation processes that use an olefinic alkylating agent.

The process includes reacting a heterocyclic amine with a monoaldehyde or a dialdehyde in a pH range of from about 8 to 14 and then quaternizing the so-reacted heterocyclic amine with an alkylating agent at a pH of not less than about 2.

The process recycles hydrogen, and can recycle halogen-containing species as well, within the process while preventing admixture of hydrogen with the alkylating agent.