A novel path toward methanol and olefins production fueled by syngas via a coupling of coke-oven gas reforming with pulverized coke chemical looping combustion

Efficient utilization of a large quantity of coke-oven gas (COG) to produce methanol and further olefins is an important technical path toward coal-to-chemicals. The current COG-to-olefins process (CGTO) suffers from inefficient utilization of hydrogen resource in the COG, limited olefins productivity, lower energy efficiency, and ultimately uncompetitive in product cost. Its major technical issues are the insufficient carbon supply and energy intensification. This study provided a novel technical path toward olefins production fueled by syngas from efficient coupling of COG reforming with pulverized coke chemical looping combustion (PCCLC). The CO2 generated by the PCCLC was used as carbon source to effectively adjust hydrogen-to-carbon ratio of syngas to 2.0, ideally adapting to methanol production first and further olefins. The coupling and integration in material streams and energy utilization were considered in the new process. Modelling and integration results supported the competitiveness of this novel process, revealing that its hydrogen efficiency and exergy efficiency can be increased to 43% and 60%, comparing to only 29% and 52% in the CGTO. The olefins capacity was also increased from 0.6 Mt/y in the CGTO to 0.9 Mt/y by an additional consumption of economic pulverized coke 0.43 Mt/y. Although total capital investment of the new process was 21% higher than the CGTO, the unit capital investment and product cost were 19% and 6% lower because of its larger olefins capacity.