Hydrogen production from thermochemical conversion has been considered the most promising technology for the use of biomass, and some novel methods are also being developed for low cost and high efficiency.

The pyrolysis of the crude glycerol from a biodiesel production plant was investigated by thermogravimetry coupled with Fourier transform infrared spectroscopy. The main gaseous products are discussed, and the thermogravimetric kinetics derived. There were four distinct phases in the pyrolysis process of the crude glycerol. The presence of water and methanol in the crude glycerol and responsible for the first decomposition phase, were shown to catalyse glycerol decomposition (second phase). Unlike the pure compound, crude glycerol decomposition below 500 K leaves behind a large mass fraction of pyrolysis residues (ca. 15%), which eventually partially eliminate in two phases upon reaching significantly higher temperatures (700 K and 970 K respectively). An improved iterative Coats-Redfern method was used to evaluate non-isothermal kinetic parameters in each phase. The latter were then utilized to model the decomposition behaviour in non-isothermal conditions. The power law model (first order) predicted accurately the main (second) and third phases in the pyrolysis of the crude glycerol. Differences of 10-30 kJ/mol in activation energies between crude and pure glycerol in their main decomposition phase corroborated the catalytic effect of water and methanol in the crude pyrolysis. The 3-D diffusion model more accurately reproduced the 4 th (last) phase, whereas the short initial decomposition phase was poorly simulated despite correlation coefficients ca. 0.95-0.96. The kinetics of the 3 rd and 4 th decomposition phases, attributed to fatty acid methyl esters cracking and pyrolysis tarry residues, were sensitive to the heating rate.3

Catalytic steam reforming of glycerol for H 2 production has been evaluated experimentally in a continuous flow fixed-bed reactor. The experiments were carried out under atmospheric pressure within a temperature range of 400-700C. A commercial Ni-based catalyst and a dolomite sorbent were used for the steam reforming reactions and in-situ CO 2 removal. The product gases were measured by online gas analyzers. The results show that H 2 productivity is greatly increased with increasing temperature and the formation of methane by-product becomes negligible above 500C. The results suggest an optimal temperature of ~500C for the glycerol steam reforming with in-situ CO 2 removal using calcined dolomite as the sorbent, at which the CO 2 breakthrough time is longest and the H 2 purity is highest. The * Author to whom correspondence should be addressed. Tel: 44 -113-3432503; Fax: 44 -113-2467310, v.dupont@leeds.ac.uk. 2 shrinking core-model and the 1D diffusion model describe well the CO 2 removal under the conditions of this work.

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