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Hydrogen production from the pyrolysis/reforming of refuse derived fuel (RDF) was investigated with a series of Ni/SiO2 catalysts. The catalysts were prepared by homogeneous precipitation derived from a sol–gel method (HPG) and compared to Ni/SiO2 catalysts prepared by adding a phase separation step to the HPG process (B-HPG). All the catalysts had a NiO loading of 10 wt.%, and three different calcination temperatures (500 °C, 700 °C and 900 °C) were used for each method. The prepared Ni/SiO2 catalysts were analysed to determine their surface area, and porosity characteristics; additionally scanning electron microscopy (SEM-EDX), transmission electron microscopy (TEM), infrared spectroscopy (FTIR), and X-Ray diffraction (XRD) analyses were carried out. The results showed that the catalyst prepared by HPG and calcined at 700 °C (HPG700), presented a relatively high surface area (∼347 m2 g−1), large pore diameter (12.50 nm), and also resulted in the highest catalytic activity towards H2 production, attaining ∼60 vol.% hydrogen. The lowest hydrogen concentration of about 42 vol.% was obtained using the catalysts prepared by the combined HPG-phase separation method, and calcined at 900 °C (B-HPG900). It was also observed that at calcination temperatures higher than 700 °C the catalytic activity for hydrogen production was diminished for both preparation methods. [ABSTRACT FROM AUTHOR]

Abstract: The production of hydrogen from the two-stage pyrolysis–gasification of polypropylene using a Ni/CeO2/ZSM-5 catalyst has been investigated. Experiments were conducted on CeO2 loading, calcination temperature and Ni loading of the Ni/CeO2/ZSM-5 catalyst in relation to hydrogen production. The results indicated that with increasing CeO2 loading from 5 to 30wt.% for the 10wt.% Ni/CeO2/ZSM-5 catalyst calcined at 750°C, hydrogen concentration in the gas product and the theoretical potential hydrogen production were decreased from 63.0 to 49.8vol.% and 50.4 to 21.6wt.%, respectively. In addition, the amount of coke deposited on the catalyst was reduced from 9.5 to 6.2wt.%. The calcination temperature had little influence on hydrogen production for the catalyst containing 5wt.% of CeO2. However, for the 10wt.% Ni/CeO2/ZSM-5 catalyst with a CeO2 content of 10 or 30wt.%, the catalytic activities reduced when the calcination temperature was increased from 500 to 750°C. The SEM results showed that large amounts of filamentous carbons were formed on the surface of the catalysts. The investigation of different Ni content indicates that the Ni/CeO2/ZSM-5 ((2-10)-5-500) catalyst containing 2wt.% Ni showed poor catalytic activity in relation to the pyrolysis–gasification of polypropylene according to the theoretical potential H2 production (7.2wt.%). Increasing the Ni loading to 5 or 10wt.% in the Ni/CeO2/ZSM-5 ((2-10)-5-500) catalyst, high potential hydrogen production was obtained. [Copyright &y& Elsevier]