Enhanced Hydrogen Production Integrated with CO2 Separation in a Single-Stage Reactor

Abstract

Hydrogen production from coal gasification can be enhanced by driving the equilibrium limited Water Gas Shift reaction forward by incessantly removing the CO 2 by-product via the carbonation of calcium oxide. This project aims at using the OSU patented high-reactivity mesoporous precipitated calcium carbonate sorbent for removing the CO 2 product.Preliminary experiments demonstrate the show the superior performance of the PCC sorbent over other naturally occurring calcium sorbents. Gas composition analyses show the formation of 100% pure hydrogen. Novel calcination techniques could lead to smaller reactor footprint and single-stage reactors that can achieve maximum theoretical H 2 production for multicyclic applications. Sub-atmospheric calcination studies reveal the effect of vacuum level, diluent gas flow rate, thermal properties of the diluent gas and the sorbent loading on the calcination kinetics which play an important role on the sorbent morphology. Steam, which can be easily separated from CO 2 , is envisioned to be a potential diluent gas due to its enhanced thermal properties. Steam calcination studies at 700-850 o C reveal improved sorbent morphology over regular nitrogen calcination. A mixture of 80% steam and 20% CO 2 at ambient pressure was used to calcine the spent sorbent at 820 o C thus lowering the calcination temperature. Regeneration of calcium sulfide to calcium carbonate was achieved by carbonating the calcium sulfide slurry by bubbling CO 2 gas at room temperature.