Process design and feasibility study of synthetic crude production by the combination of methane decomposition, reverse water gas shift reaction, and Fischer-Tropsch synthesis

Abstract

In this dissertation, the conversion of CO2 to gas-to liquid (GTL) products was investigated for the production of 30000 bbl per day syncrude. The GTL plant consisted of four main units: hydrogen production by catalytic thermal decomposition of methane in a Cu-Bi molten media, syngas production by the reverse water gas shift (RWGS) reaction using a nickel-based catalyst, syncrude production by the low temperature Fischer-Tropsch (LTFT) synthesis over a cobalt-based catalyst, and an energy recovery unit for electricity generation. The plant was simulated by the coupling of HYSYS and MATLAB to simulate the RWGS and FT reactors and converge their recycle streams. 150 alkanes and 149 alkenes were included in the simulation to accurately estimate the product distribution of the FT reactor. The fixed capital investment of the plant and the manufacturing cost of syncrude were $1.6 billion and $137 bbl-1 , respectively. It was found that hydrogen production by methane decomposition reduced the manufacturing cost of syncrude by 32% when compared to GTL plants that sourced their hydrogen from water electrolysis. The profitability analysis showed the plant could not be economically viable without selling the produced solid carbon. The breakeven price of the produced solid carbon was estimated to be $633 tonne-1 for a syncrude selling price of $59.31 bbl-1 . The economic performance of the plant was highly favourable at syncrude selling prices higher than $80 bbl-1 . It was determined that the plant was a net emitter of CO2 at a rate of 19.92 g CO2 per 1 MJ of syncrude, which was lower than the reported values for different types of natural-gas based GTL plants, but higher than water electrolysis-FT plants.