Catalytic Steam Reforming of Biomass-Derived Fractions from Pyrolysis Processes

Biomass conversion via hydrolytic, solvolytic, and pyrolytic processes generates liquid streams that, after separation of marketable products, can be used to produce either syngas or hydrogen, a strategy being considered in this work. Catalytic steam reforming of model oxygen-containing compounds, thier mixtures, bio-oil, and its fractions has been studied using Ni-based catalysts. Testsperformed on a microreactor interfaced with a molecular beam mass spectrometer showed that, by proper selection of the process variables: temperature, steam-to-carbon ratio, gas hourly space velocity, and contact time, almost total conversion of carbon in the feed to CO and CO(2) could be obtained. These tests also provided possible reaction mechanisms where thermal cracking competes withcatalytic processes. Bench-scale, fixed bed reactor tests demonstrated high hydrogen yields from model compounds and carbohydrate-derived pyrolysis oil fractions. Reforming bio-oil or its fractions required proper dispersion of the liquid to avoid vapor-phase carbonization of the feed in the inlet to the reactor. A special spraying nozzle injector was designed and successfuly tested with anaqueous fraction of bio-oil. The techno-economic assessment showed that the process could be economically viable if the lignin-derived oil fraction was sold for adhesives and only carbohydrate-derived fraction was converted to hydrogen.