Rate and selectivity modification in fischer—tropsch synthesis over charcoal supported molybdenum by forced concentration cycling

Forced concentration cycling of the feed between pure CO and pure H 2 was used to successfully change both the selectivities and reactivities of promoted and unpromoted charcoal supported molybdenum catalysts in Fischer‐Tropsch synthesis. It was found that with the unpromoted catalyst the rate enhancement increases with temperature and selectivity shifts towards methane. At the lower temperatures concentration cycling increases selectivity to ethane and higher hydrocarbons to levels only achievable with promoted catalysts. Periodic operation with the potassium promoted catalyst results in small rate enhancements but the olefin to paraffin ratio is dramatically changed without changing the carbon number distribution.