Renewable hydrogen production from biogas by sorption enhanced steam reforming (SESR): A parametric study

Abstract H2 production from biogas (60%CH4 + 40%CO2) by sorption enhanced steam reforming (SESR) was thermodynamically and experimentally studied in a fluidized bed reactor. Biogas is an interesting renewable biomass resource for hydrogen production due to its sustainable nature. SESR combines the catalytic reforming reaction of biogas with simultaneous CO2 removal in a single step. A Pd/Ni-Co hydrotalcite-like material (HT) was used as catalyst and dolomite as CO2 sorbent. The effects of temperature (550-800 oC), steam/CH4 molar ratio (2-6) and gas hourly space velocity (GHSV) (492-3937 mL CH4 gcat-1 h-1) on the process performance were evaluated. CO2 in biogas was effectively removed by the sorbent from the gas phase at 550-700 oC, without influencing the reforming process. H2 yield increased with temperature from 550 to 650 oC, but H2 concentration decreased at temperatures higher than 600 oC, requiring a tradeoff between both parameters to select an optimum operating temperature. H2 purity of 98.4 vol.% was obtained at 550-600 oC and H2 yield of 92.7% was reached at 650 oC. Higher steam/CH4 ratios enhance the process, whereas higher space velocities decrease H2 yield. Results demonstrate that high-purity high-yield biohydrogen can be produced by the SESR of a renewable biomass resource as biogas.