Production of Hydrogen and Syngas via Steam Gasification of Glycerol in a Fixed-Bed Reactor

Abstract

Glycerol is one of the by-products of transesterification of fatty acids to produce bio-diesel. Increased production of bio-diesel would lead to increased production of glycerol in Canadian market. Therefore, the production of hydrogen, syn gas and medium heating value gas is highly desirable to improve the economics of bio-diesel production process. In this study, steam gasification of pure and crude glycerol was carried out in a fixed-bed reactor at the liquid hourly space velocity (LHSV) and temperature of 0.77 h⁻¹ and 800 °C, respectively. In this process, the effects of different packing materials such as quartz particle and silicon carbide were studied. Catalytic steam gasification was performed in the presence of commercial Ni/Al₂O₃ catalyst in the range of steam to glycerol weight ratio of 0:100–50:50 to produce hydrogen or syngas when LHSV was maintained constant at 5.4 h⁻¹. Pure glycerol was completely converted to gas containing 92 mol% syngas (molar ratio of H₂/CO ≈ 1.94) and the calorific value of 13 MJ/m³ at 50:50 weight ratio of steam to glycerol. Hydrogen yield was increased by 15 mol% via the steam gasification process when compared to pyrolysis process. The presence of catalyst increased further the production of hydrogen and total gas in case of both pure and crude glycerol indicating their strong potential of making hydrogen or syngas. Maximum hydrogen, total gas and syn gas production of 68.4 mol%, 2.6 L/g of glycerol and 89.5 mol% were obtained from glycerol using Ni/Al₂O₃ catalyst at temperature and steam to glycerol ratio of 800 °C and 25:75, respectively.