a process for the isomerization of c 4 - c 6 paraffins that uses a highly active catalyst to isomerize the feed in the presence of very little hydrogen . the process is characterized by good stability and high conversion with effluent hydrogen to hydrocarbon ratios of 0 . 05 or less . continued operation at low hydrogen concentrations is made possible by the remarkably low coking tendency of the catalyst , especially during periods of temporary sulfur deactivation . the low hydrogen to hydrocarbon ratio simplifies the process and makes it cheaper to operate by eliminating facilities for the recovery and recycle of hydrogen .