Towards efficient hydrogen production from glycerol by sorption enhanced steam reforming

Abstract

An increase in glycerol production is a consequence of the rapid growth in bio-diesel production and makes it attractive to utilize glycerol as feedstock, e.g., for production of hydrogen. Here we report integrating the glycerol steam reforming and CO2 capture reaction in one single reactor as a potential approach to enhance the efficiency of hydrogen production. A thermodynamic analysis comparing glycerol steam reforming with or without CO2 capture was made, highlighting that integration of CO2 removal allows high efficiency in the hydrogen production and energy utilization. The experimental assessment on the integrated reaction was carried out with Co–Ni reforming catalysts derived from hydrotalcite-like material (HTls) and dolomite as CO2 acceptor. The applied operating window was at a steam-to-glycerol ratio in a range of 3– 9 and a temperature of 500–650 °C. The obtained hydrogen content or purity was close to the theoretical boundary at temperatures above 575 °C or steam-to-glycerol ratio no less than 4. Particularly, both the hydrogen yield and purity were at approx. 99% with a steam-to-glycerol ratio of 9. At a lower steam-to-glycerol ratio of 3 and temperature lower than 550 °C, hydrogen production was compromised due to the low efficiency of steam reforming and a high tendency of pyrolysis. The elimination of non-catalytic reactions, sufficient methane steam reforming and water gas shift reaction have been identified as critical factors to maximize hydrogen yield in sorption enhanced reforming of glycerol.