Although they may be present in crudes, these two are removed from intermediate or final products, not only for economic reasons but also for the following:
-mercaptans can also be formed by decomposition of organic sulphur compounds during normal processing.
-H2S is formed by thermal and catalytically decomposition of sulphur compounds during distillation, cracking, reforming, etc.
The technical literature is full of commercial processes used for their removal by using soda at one end up to hydotreating at the other.