Hydrogen production via catalytic steam reforming of fast pyrolysis bio-oil in a two-stage fixed bed reactor system

Abstract

Hydrogen production was prepared via catalytic steam reforming of fast pyrolysis bio-oil in a two-stage fixed bed reactor system. Low-cost catalyst dolomite was chosen for the primary steam reforming of bio-oil in consideration of the unavoidable deactivation caused by direct contact of metal catalyst and bio-oil itself. Nickel-based catalyst Ni/MgO was used in the second stage to increase the purity and the yield of desirable gas product further. Influential parameters such as temperature, steam to carbon ratio (S/C, S/CH 4), and material space velocity (W BHSV, GHSV) both for the first and the second reaction stages on gas product yield, carbon selectivity of gas product, CH 4 conversion as well as purity of desirable gas product were investigated. High temperature (> 850 °C) and high S/C (> 12) are necessary for efficient conversion of bio-oil to desirable gas product in the first steam reforming stage. Low W BHSV favors the increase of any gas product yield at any selected temperature and the overall conversion of bio-oil to gas product increases accordingly. Nickel-based catalyst Ni/MgO is effective in purification stage and 100% conversion of CH 4 can be obtained under the conditions of S/CH 4 no less than 2 and temperature no less than 800 °C. Low GHSV favors the CH 4 conversion and the maximum CH 4 conversion 100%, desirable gas product purity 100%, and potential hydrogen yield 81.1% can be obtained at 800 °C provided that GHSV is no more than 3600 h − 1 . Carbon deposition behaviors in one-stage reactor prove that the steam reforming of crude bio-oil in a two-stage fixed bed reaction system is necessary and significant.