A New Approach to Control of CO ₂ Emission and Optimal Use of C and H for Production of Desired Syngas from Coal

Abstract

Coal is a rich-in-C and poor-in-H material. How should we maximize uses of C and H in coal for producing desired gases eventually converted to liquid chemicals with minimal CO2 emission? This research is designed to make progress in overcoming the challenges through development of a two-stage coal processing. The technology is applicable to any coal, although Power River Basin (PRB) coal is used as an example feedstock in this research. In the 1st stage or pyrolysis process of the low-carbon-footprint technology, a Na-Fe bimetallic catalyst was found to be able to not only enhance the yield of CO and ratio of H2/CO but also lower CH4 and CO2 yields with the presences of the Na-Fe catalyst, which are desired because the produced gas is an ideal syngas. In the 2nd stage or gasification of the char obtained from pyrolysis stage with CO2 for producing almost 100%-purity CO without presence of H2O. The CO2 as the major byproduct of the 1st stage could be used as a raw material in the 2nd stage, which is an ideal process integration for significant reduction in CO2 emission. Also, the Na-Fe catalyst can accelerate not only the reaction kinetics in both stages but also increase the H¬2/CO ratio in the syngas produced in the 2nd stage. In other words, the catalyst is a multifunctional agent, which can not only intensify the overall coal process efficiency but also improve the qualities of the products and reduce CO2 emission.

Keywords: Coal, catalysis, pyrolysis, gasification, ideal syngas, CO2 reduction