Calcium Looping Process (CLP) for Enhanced Steam Methane Reforming

Abstract

Carbon dioxide (CO2) capture using calcium-based sorbents for post- and pre-combustion applications has the potential to become a viable technology. When applied to a pre-combustion system, the presence of calcium sorbents facilitates process intensification by combining the CO2 removal step with the reactions generating the fuel gas [syngas, hydrogen (H2), etc.] in a single step. Such a process is also capable of producing a high-purity sequestration-ready CO2 stream. The enhanced steam methane reforming (SMR) using the Calcium Looping Process (CLP) has been investigated in this work. The CLP comprises three reactors: the carbonation reactor or carbonator where the thermodynamic constraint of the reforming and water gas shift (WGS) reaction is overcome by the incessant removal of the CO2 product resulting in the production of high-purity H2, the calciner where the calcium sorbent is regenerated and a sequestration-ready CO2 stream is produced, and the hydrator where the regenerated sorbent is reactivated to improve its multicyclic performance. The exothermic carbonation and WGS reaction convert the highly endothermic SMR into a heat neutral process, thus reducing the temperature of reforming from >900 to 650 °C. Experiments conducted using methane in a bench-scale fixed bed reactor have indicated that high purity H2 (∼95–99%, dry basis) can be produced using the CLP with in situ CO2 capture. Attempts to maintain the sorbent reactivity over multiple cycles using hydration have yielded encouraging results.