Feasibility Study of CO2 Mitigation with Methanol Production through Hydrogenation and Bi-Reforming of Natural Gas

Abstract

Chemical conversion of carbon dioxide (CO2) to methanol has the potential to address two relevant sustainability issues: economically feasible replacement of fossil raw materials and avoidance of greenhouse gas emissions. However, chemical stability of CO2 is a challenging impediment to conversion, requiring harsh reaction conditions at the expense of increased energy input, adding capital, operational and environmental costs. This work evaluates two innovative chemical conversion of CO2 to methanol: the indirect conversion, which uses synthesis gas produced by bi-reforming as intermediate, and the direct conversion, via hydrogenation. Process simulations are used to obtain mass and energy balances, needed to support economic analyses. Due to the uncertainties in the raw material prices, including CO2 and hydrogen (H2), its limits for economic viability are estimated and sensitivity analyzes are carried in predetermined prices (base cases). It is considered the scenario of free CO2 available in atmospheric conditions, as in a bioethanol industry, but the sensitivity analyses show the results for other scenarios, as in a CO2 rich natural gas, in which the cost of processing CO2 is zero. The economic analyses show that hydrogenation can be feasible if hydrogen prices are lower than 1000 US$/t, while the indirect route is viable only for cheap sources of natural gas below 3.7 US$/MMBtu. The CO2 pre-treatment costs are not as sensible as the others raw materials.