Enhanced hydrogen production by the catalytic alkaline thermal gasification of cellulose with Ni/Fe dual-functional CaO based catalysts

Abstract

A two-stage system involving alkaline thermal gasification of cellulose with Ca(OH)2 sorbent and catalytic reforming with Ni/Fe dual-functional CaO based catalysts is proposed and applied to enhance H2 production and in-situ CO2 capture. The results show that the H2 concentration is maximized at a considerably lower temperature (500 °C) than commercialized biomass gasification processes, reducing energy consumption. Sol-gel method is deemed better than impregnation method for its lower cost and higher-concentration H2 production. Among the prepared catalysts, sol-NiCa catalyst exhibits the best performance in CO2 absorption, resistance to carbon deposition, and cyclic stability, creating maximum H2 concentration (79.22 vol%), H2 yield (27.36 mmol g−1 cellulose), and H2 conversion (57.61%). Introduction of Ni rather than Fe on the CaO based catalyst promotes steam methane reforming at moderate temperature range of 400–600 °C, generating low contents of CH4 (5.38 vol%), CO2 (4.82 vol%), and CO (10.58 vol%).