Fischer–Tropsch Synthesis: Using Deuterium as a Tool to Investigate Primary Product Distribution

Abstract

Accumulation of products is a known phenomenon associated with a continuously stirred tank reactor (CSTR). Secondary reactions of α-olefins due to prolonged bed/pore residence time can significantly change the primary Fischer–Tropsch product distribution. Using D2 as a tracer, this study first investigated the significance of Fischer–Tropsch product accumulation in a CSTR. Secondly, the D2 tracer study was used to investigate primary product distribution and olefin to paraffin ratios. Based on the D2 study, it was found that Fischer–Tropsch synthesis with a 2.5 % Ru/NaY catalyst follows a single α mechanism with a chain growth probability of about 0.74. Both olefins and paraffins are primary products and the ruthenium catalyst produced a similar olefin/paraffin ratio for each carbon number. The apparent decline of the O/P ratio for higher carbon number products was shown to be due to secondary reactions of the olefin at prolonged residence times. D2 tracing was shown to be a versatile tool to investigate product accumulation and to define primary product distribution which is very important for mechanistic interpretation and kinetic modeling.