Techno-Economic Analysis of Integrating a CO2 Hydrogenation-to-Methanol Unit with a Coal-to-Methanol Process for CO2 Reduction

A coal-to-methanol (CTM) process is one of the great important industrial methanol production processes, which has attracted a lot of attention in light of dwindling petroleum sources and rising prices of natural gas and oil. However, the CTM process will typically result in a certain amount of CO2 emission and thereafter lead to severe environmental problems. Facing historic global warming, a carbon emissions trading system drives the CTM process to adopt CO2 reduction technologies. In this paper, a CO2 hydrogenation-to-methanol unit, regarded as one of the most promising technology for CO2 reduction, is integrated with the CTM process to achieve CO2 reduction under the carbon emissions trading system. A detailed simulation of the CTM process integrated with the CO2 hydrogenation-to-methanol unit is built based on a typical industrial process. Mass and energy balance results indicate that the CTM process without a CO2 reduction unit emits 3.1 kg of CO2.kg CH3OH-1. The CO2 hydrogenation-to-methanol unit, consuming 0.12 kg of H-2 and 7.4 MJ of energy, could achieve a net CO2 reduction with H-2-associated CO2 emission below 1.8 kg of CO2.kg H-2(-1). The energy efficiency of the CTM process only slightly decreases from 52.9 to 51.6% when the carbon cap drops from 3.1 to 2 kg of CO2.kg CH3OH-1. Furthermore, an overall profit could be obtained with the CO2 hydrogenation unit when the H-2 price is under the critical point at 1.4 US$.kg H-2(-1).