The work presented in this manuscript focuses on a systematic understanding of the effects of the activating agents (H2 and syngas) on P/O ratios over a precipitated iron catalyst for Fischer-Tropsch synthesis (FTS) using long duration runs at 250 oC, 8 ml(NTP)/min/gcat and 6 bar gauge. Different reaction behaviours were observed for FTS with the time on stream from 1100 hours to 2200 hours: the CO conversion was gradually decreased from 65% to 46% and the O/P ratios were also dropped accordingly for the reactor reduced by syngas; while for the catalyst activated by H2, the CO conversion and O/P ratio were firstly dropped a little bit, and then increased to reach almost the same levels as the one reduced by syngas, respectively. Although the higher activity and P/O had been measured for the catalyst reduced by syngas with time on stream from 1100 hour to 2200 hours, the similar CO conversions and P/O ratios were achieved for the catalyst reduced by both syngas and H2 after 2200 hours runs of the experiments, which indicates that no matter which kind of reducing agent used to reduce the catalyst, the catalyst performance tend to fairly the same for the iron catalyst after a period running (2200 hours for this work). Despite the P/O ratio varied with different reaction conditions, when we use “Yao plot” to re-present our data, the linear relationship between P(n+1)/O(n+1) and Pn/On were obtained which indicated the inner constraints between the olefin product distribution and the paraffin product distribution. The research results disclose some hints on the potential flexibility there is for the design of the FT catalyst and the FTS process.

Fischer–Tropsch synthesis: Comparative study of paraffin to olefin ratio over an iron-based catalyst activated by both syngas and H2

2019 Fall National Meeting

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