Advanced steam reforming of pyrolysis oils and their aqueous phase

This thesis presents a feasibility study on the conversion of biomass-derived pyrolysis oils to hydrogen gas via the advanced steam reforming processes of chemical looping reforming (CLR) and sorption enhanced steam reforming (SESR). According to thermodynamic equilibrium, the optimum conditions of steam reforming of model pyrolysis oils compounds were around 600°C and molar steam to carbon ratio (S/C) of 3, to save raising excess steam in the process. Palm empty fruit bunches (PEFB) pyrolysis oil and pine pyrolysis oil were investigated as renewable feedstock for H2 production. The experiments were carried out in a down-flow packed bed micro reactor using commercial Ni catalyst at 1 atm. The SIC of 1.89 (moist fuel) was found to provide the best operating conditions for steam reforming of both pyrolysis oils. In the SESR experiments, dolomite was mixed in the reactor bed to capture C02 produced from the steam reforming of pyrolysis oils. High sorption enhancement effects were demonstrated in particular for pine oil. Short CLR experiments were performed tor both oils using the same Ni catalyst acting as oxygen transfer material. The oils were able to reduce the catalyst close to 90% despite high O-content, and undergo CLR. The feasibility of steam reforming of aqueous fraction of pyrolysis oils was performed with co-reforming of ethanol using two catalysts: 'A' with a NiO loading of 18 wt% on α-alumina, and 'B' with 25 wt% NiO on γ-alumina. The aqueous phase was derived from water phase separation of the pine oil at a 1: 10 oil :water mass ratio. Both catalysts demonstrated high fuel conversion and H2 yield for S/C ratios between 2.4 and 4.8. Chemical looping reforming performed at S/C of 3.66 resulted in almost 90% reduction of catalyst A and around 20% reduction of catalyst B whilst maintaining nearly complete fuel conversion.EThOS - Electronic Theses Online ServiceGBUnited Kingdo