ABSTRACT
Most alkylations are acid catalyzed either by a homogeneous liquid strong-acid catalyst (H
SO
, H
PO
, HF, AlCl
) or a solid strong-acid, which has been used where feasible and economical (zeolites, supported acids, acidic ion-exchange resins). Developments with heterogeneous catalysts were driven, in part, by efforts to minimize waste disposal problems associated with spent acids. Not all alkylation processes, however, have been amenable to the use of a heterogeneous acid catalyst which, in some reaction systems, produces coke at a rapid rate. Thus, the production of alkylate gasoline from isobutane and olefins continues to employ either liquid sulfuric or hydrofluoric acid. Major improvements in handling and reducing acid consumption, and thus waste acid quantities, have proved successful in such processes.
