Chemical Technology August 2016

PETROCHEMICALS

A catalytic membrane reactor for mitigating water-induced catalyst deactivation in Fischer-Tropsch synthesis by Michael O Daramola, PhD, CEng, MIChemE, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, South Africa Fischer-Tropsch (F-T) synthesis is a surface-catalysed polymerisation reaction that involves conversion of synthesis gas (CO and H 2 ) derived from coal, natural gas, heavy oil or biomass into hydrocarbons. In this article, a catalytic membrane reactor is proposed for mitigating the effect of water-induced deactivation of F-T catalyst during synthesis.

I n recent times, strict regulations and policies on envi- ronment to reduce environmental pollution and degra- dation are constantly being formed and implemented. Therefore, diversification of sources of fossil fuels, the major sources of environmental pollution, and the utilisa- tion of stranded gas have re-awakened global interest in Fischer-Tropsch (F-T) synthesis. Synthetic liquid fuels, major products of F-T synthesis, have a very low content of sulphur and aromatic compounds compared to fossil fuels and are thus preferred as clean fuels for a clean environment. Besides the environmental concerns, abundant reserves of natural gas in many parts of the world have ignited global interest in F-T synthesis and new plants based on F-T syn-

thesis technology are now commissioned periodically [1]. Fischer-Tropsch synthesis is a surface-catalysed poly- merisation reaction that involves conversion of synthesis gas (CO and H 2 ) derived from coal, natural gas, heavy oil or biomass into hydrocarbons consisting of paraffins, olefins, alcohols and aldehydes. Production of the syngas from coal, natural gas, heavy oil or biomass could be through steam reforming (for natural gas) and gasification (for coal, oil and biomass). The long-chain linear paraffins obtained from F-T synthesis are cracked further into short-chain hydrocarbons in fluidised-bed catalytic cracking (FCC) units [2]. In addition, recent developments in the design of process-intensified bi-functional Co-based catalysts, that could combine F-T

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Chemical Technology • August 2016