High yield hydrogen from the pyrolysis-catalytic gasification of waste tyres with a nickel/dolomite catalyst

Nickel/dolomite catalysts have been prepared and investigated for their suitability for the production of hydrogen from the two-stage pyrolysis-gasification of waste tyres. Experiments were conducted at a pyrolysis temperature of 500 °C and gasification temperature was kept constant at 800 °C with a catalyst/waste tyres ratio of 0.5. Fresh and reacted catalysts were characterised using a variety of methods, including, BET, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM)-energy dispersive X-ray spectrometry (EDXS). The results indicated that the gas yield was significantly increased from 30.3 to 49.1 wt.% and the potential H production was doubled with the introduction of 5%Ni into the calcined dolomite catalyst. The results show also a further increase in the gas yield and the potential H production with increasing Ni loading from 5 to 20 wt.%. The coke deposited on the catalyst surface was 3.1, 0.9, 2.8 and 3.7 wt.%, when the Ni loading was 0, 5, 10 and 20 wt.% for the calcined dolomite catalyst, respectively. The results showed that the calcined Ni dolomite catalysts became deactivated by filamentous carbons.