US EPA

8306538 

Meetings & Symposia 

Effects of supercritical fluid extraction on the activity and selectivty of Fischer Tropsch catalysts 

Durham, E; Bordawekar, M; Roberts, CB 

2007 

0 

Abstracts of Papers of the American Chemical Society
ISSN: 0065-7727 

AMER CHEMICAL SOC 

Boston, MA 

234th ACS National Meeting 

English 

WOS:000207593903742 

We have shown that supercritical phase Fischer Tropsch Synthesis (SC-FTS) offers better activity maintenance than gas phase Fischer Tropsch Synthesis (GP-FTS). Consequently, the question as to whether the supercritical media (with or without syngas) can restore the activity lost during GP-FTS is of interest. To that end, experiments were performed with a series of gas phase FTS runs separated by a supercritical hexanes washing stage. Conventional GP-FTS was followed by washings with super-critical hexanes and was repeated over several cycles. After the third gas phase cycle, the hexanes flushing stage was performed in the presence of syngas, e.g. SC-FTS, instead of simply flushing with hexanes in the absence of syngas. This allowed the investigation of the effects of the reactive FTS environment versus simple extraction. In addition to a loss in conversion, a number of changes in the product selectivity with time on stream were observed during gas-phase operation including decreased methane selectivity and carbon dioxide selectivity, increased C3 olefin selectivity, and increased water selectivity. The SC-washings showed some capacity to restore lost activity and affected the selectivities.