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.

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.

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

Steam reforming of the crude glycerol by-product of a biodiesel production plant has been evaluated experimentally at atmospheric pressure, with and without in-situ CO 2 sorption, in a continuous flow fixed-bed reactor between 400 and 700 °C. The process outputs were compared to those using pure glycerol. Thermodynamic equilibrium calculations were used to assess the effect on the steam reforming process of the main crude impurities (methanol and four fatty acid methyl esters). The crude glycerol and steam conversions and the H 2 purity reached 100%, 11% and 68% respectively at 600 °C. No CH 4 was found at and above 600 °C. Steam reforming of crude glycerol with in-situ CO 2 removal is shown to be an effective means of achieving hydrogen purity above 88% in pre-CO 2 breakthrough conditions.

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CO2 flooding is used extensively as a commercial process for enhanced oil recovery. In this study, the visualization of CO2 flooding in immiscible and miscible displacements in a high-pressure condition was studied using a 400 MHz MRI system. For CO2 immiscible displacement, the phenomenon of CO2 channelling or fingering was obviously due to the difference in fluid viscosities and densities. Thus, the sweep efficiency was small, and the final residual oil saturation was 37.2%. For CO2 miscible displacement, the results showed that pistonlike displacement occurred, and the phenomenon of the miscible regions and CO2 front was obvious. The viscous fingering and gravity override caused by the low viscosity and density of the gas were restrained effectively, and the velocity of the CO2 front was uniform. The sweep efficiency was high, and the final residual oil saturation was 13.5%, indicating that CO2 miscible displacement could recover more oil compared with CO2 immiscible displacement. Finally, the average velocity of the CO2 front was evaluated by analyzing the oil saturation profile. A special core analysis method was applied to in situ oil saturation data to directly evaluate the effect of viscosity, buoyancy, and capillary pressure on CO2 miscible displacement.

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