Effect of Support Particle Size in Fischer–Tropsch Synthesis: the Use of Natural Clinoptilolite as Support

Abstract

In the past, Fischer–Tropsch (FT) coal/biomass-to-liquids projects have required a significant initial investment. The high price of the catalysts used is one area where costs could be reduced. This research explored the possibility of using clinoptilolite as a catalyst to reduce costs without sacrificing performance. The as-received clinoptilolite was ground and sieved to yield different size classes. For this study, three size classes were investigated as the support for an FT catalyst: −75 to +53 μm; −53 to +38 μm; less than 25 μm. Using a fixed bed reactor, 10% cobalt supported on these various supports was synthesized and evaluated. The maximum CO conversion obtained was 44.97% when using the −53 to +38 μm size class with the experiments carried out at 220 °C, 2 L(NTP)/(gcat h) and 10.85 bar(abs). A one-way analysis of variance was performed. Then a posthoc Bonferroni adjustment test was carried out to determine whether or not the utilization of different support size classes affected CO conversion. The results indicated a significant difference in CO conversion, with P(T ≤ t) two-tail values ranging from 6.08 × 10–5 to 2.37 × 1027. At 220 °C and 10.85 bar(abs), methane selectivity ranged between 14.95 and 16.97% for the support class sizes studied, while C2–C4 selectivity ranged between 14.55 and 19.01%, and C5+ selectivity ranged between 66.04 and 70.29%. The acquired product selectivity results using this cheaper support are comparable to those reported in the literature. These discoveries might have valuable implications for the design of a catalyst that can be used in the coal/biomass to liquid process.