The use of sulfur to extract hydrogen from coal

The world's recoverable coal reserves contain about 3 × 10¹⁰ tons of hydrogen. The reaction of sulfur vapor with medium-volatile bituminous coal produces hydrogen sulfide in yields up to 97% (based on sulfur), and utilizes 70–75% of the hydrogen from the coal. The conversion of hydrogen sulfide to hydrogen can be effected through commercially proven processes; several laboratory-scale processes could also be scaled up for future use. The solid by-product of the coal–sulfur reaction meets or exceeds specifications for fixed carbon, ash, and friability of conventional metallurgical coke, though produced at lower temperatures than typical by-product coke ovens. A conceptual process is presented in which sulfur is converted to hydrogen sulfide by reaction with coal, the hydrogen sulfide in turn is converted to the desired hydrogen and to sulfur, and the sulfur is recycled through the reactor. The by-product is a good quality coke, but may also have other applications as a carbon material.