Rational design of process parameters for carbon-neutral and sulfur-free motor fuel production from second-generation biomass generated syngas

Abstract

The carbon-neutral fuel produced from Fischer-Tropsch synthesis using H2/CO/CO2 mixture generated from gasification of second-generation biomass could be a replacement to the conventional crude-based fuel with an additional impressive feature of utilizing the greenhouse gas efficiently. The present study focuses upon multiple-response optimisation of process parameters in low-temperature Fischer-Tropsch reaction conditions with hydrogen deficient and carbon dioxide containing syngas feed reacted over a supported bimetallic catalyst developed and reported by the same group. Herein, we performed 28 experimental runs in a laboratory-scale high-pressure fixed-bed reactor for developing a quadratic model for identifying significant variables influencing process practicality. The developed regression models were statistically validated within a 95% confidence interval. The contribution of an individual, square and second-order interaction of process variables in the Fischer-Tropsch reaction performance are identified. A highest CO consumption rate of 13.9 mmol h−1 gcat−1 with minimum 6.8% CH4 selectivity and maximum 72.3% selectivity towards the C5+ hydrocarbons is achieved with a composite desirability of 0.94. These results are experimentally validated by performing confirmatory experiments at optimal process parameters. The distillation characteristics of liquid hydrocarbon product collected at the optimal conditions show similar T-50 cut with the commercially available refinery diesel fuel. The quality and quantity of the coke deposited on catalyst during a time-on-stream run were also evaluated and found to help this reaction.