Bio-oil and Hydrogen from Biomass.

摘要

Hydrogen can be produced from biomass by fast pyrolysis followed by catalytic steam reforming. Pyrolysis of biomass yields three different phases: bio-oil which is a mixture of various organic molecules and water, char, and non-condensable gases. Bio-oil has the advantages of easy storage and transport because of the higher energy density, compared to biomass, and can be considered a key intermediate product in the conversion of biomass to hydrogen. Efficiency may be gained if the biomass fast pyrolysis and the processing of bio-oil to hydrogen are carried out at different locations. The first stage is to apply fast pyrolysis to bulky and low density biomass and thus convert it into an easy-to-transport intermediate with a high volumetric energy density (bio-oil). The second stage is to steam reform the produced bio-oil into a combustible gas mixture including hydrogen at a different location, close to the existing infrastructure for hydrogen use or distribution. This study was divided into two phases. In the first phase bio-oil was produced from sawdust in two separate reactors: a fixed-bed, and a fluidized-bed. In the second phase, a commercial bio-oil was used to produce hydrogen. Three apparatuses (a fixed-bed pyrolyzer, a fluidized-bed pyrolyzer, and a fixed-bed steam reformer) were designed and built in this study.;Production of hydrogen from catalytic steam reforming of bio-oil was investigated in a fixed bed tubular flow reactor over four groups of nickel-based catalysts developed in this research: nickel/alumina (Ni/Al2O 3), nickel/alumina promoted with Ru (Ru-Ni/Al2O3), nickel/alumina promoted with Mg (Ni-MgO/Al2O3), nickel-based catalysts supported on zirconia (Ni/ZrO2). The efficiencies of these four groups of catalysts were examined in term of hydrogen production.;Keywords: fast pyrolysis, bio-oil, sawdust, steam reforming, hydrogen;Employing a fixed-bed tubular reactor system, the roles of the pyrolysis temperature, sweep gas flow rate, condensation temperature and heating rate on the yields of the products were investigated. To improve the bio-oil yield, a 100 g/h biomass fluidized-bed pyrolysis system was designed, built in our lab and tested for sawdust conversion. The fluidized-bed system was used to investigate the effects of pyrolysis temperature, feedstock particle size, and vapour residence time on the product distribution and the qualities of the liquid and the char products. The following characterization tests were performed to analyze the feedstocks and products: elemental and thermo-gravimetric analyses, Karl Fischer titration, and gas chromatography/mass spectrometry (GC-MS).