Techno-Economic and Sustainability Analysis of the Production of Acetic Acid from Methane and Carbon Dioxide

Methane and carbon dioxide together represent 90% of greenhouse gases, and one way of diminishing their emissions is by converting them into added value chemicals. Acetic acid is one of such chemicals, and efforts at the laboratory scale have been carried out to prove it can be directly and indirectly synthesized from CH4 and CO2. However, there are very few studies that evaluate the possibility of implementing any of these processes at a larger scale. In this thesis, techno-economic and sustainability analyses were used to assess the feasibility of upscaling two pathways to produce acetic acid: (1) by direct conversion of methane and carbon dioxide using a plasma-assisted reactor and (2) by indirect catalytic conversion, using syngas (obtained from dry methane reforming) as an intermediate. ASPEN Plus was used for simulation, and with literature values and plant cost estimation techniques, the capital and operational expenses were estimated and compared to those of the commercial route. The indirect and direct pathways attained return on investment (ROI) values of 1.5% and 5.5%, respectively, and unless credit is given to the reduction in the carbon footprint, neither process can economically compete with the commercial route, which attained an ROI of 19%. In terms of sustainability, the indirect and direct processes captured 0.7 and 2.5 times more carbon dioxide compared to the emitted amount by the commercial pathway. For the direct pathway it was found through a sensitivity analysis the carbon credit value can be reduce down to a value of $50/tonne to render the process economically viable. Keywords: plasma-assisted; sustainability; process upscaling; carbon capture; greenhouse gases