Novel coal-to-methanol process with near-zero carbon emission: Pulverized coal gasification-integrated green hydrogen process

The coal-to-methanol (CTM) is an important technical route for methanol production. The process suffers from high CO2 emission and low energy efficiency due to the mismatch of H/C (hydrogen-to-carbon) ratio between raw coal and products. Hydrogen production from renewable energy can be introduced into the system to meet the H/C ratio. In this paper, a novel CTM process with near-zero carbon emission has been proposed, the direct CO2 emission is decreased from 1.9 to 0.035 t CO2 & BULL;t(- 1) MeOH. The novel process avoids requirement of the water gas shift unit to reduce the production of CO2 from the source, and a novel acid gas removal process is proposed to remove sour gas while ensuring the reduction of CO2 loss. Compared with traditional CTM, CO2 emission intensity, carbon utilization efficiency and energy efficiency of the novel process are 88.87% lower, 130.77% higher, and 39.64% higher, respectively. The novel process is economically feasible when the H2 price is less than 10.36 CNY & BULL;kg(-1) H2 and the carbon tax is higher than 223.3 CNY & BULL;t(-1) CO2. This study will enable both economic and environmental route for methanol production in the future and will facilitate future studies on the integration and management of CTM coupled renewable energy.

Automated summary

Coal-to-methanol is an important technical route for methanol production, but it suffers from high CO2 emissions and low energy efficiency due to the mismatch in hydrogen-to-carbon ratio. This paper proposes a novel CTM process that introduces hydrogen production from renewable energy to meet the ratio, resulting in significantly reduced CO2 emissions and improved carbon utilization and energy efficiency. Economically, the novel process is feasible under certain hydrogen prices and carbon tax levels.