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.