Steam reforming of biodiesel by-product to make renewable hydrogen

The aim of this paper was to investigate the viability of steam reforming the combined glycerol and water by-product streams of a biodiesel plant. A platinum alumina catalyst was used to optimise the operating conditions for glycerol steam reforming and mass spectroscopy was chosen to measure reformer gas yield. The problem is that glycerol steam reforming is relatively untested even with pure glycerol and the by-product quality may be too poor. The strategy was therefore to optimise the process using pure glycerol and compare the performance with by-product glycerol. To test catalyst degradation caused by carbon deposition, a Solid Oxide fuel cell (SOFC) was used as a separate reformer and electrical performance was measured to indicate carbon deposition. This is the first time a SOFC has been run on glycerol. The results showed that thermodynamic theory can be used to predict reformer performance. At high temperatures high gas yield can be reached (almost 100%) and selectivities of 70% (dry basis) obtained. The optimum conditions for glycerol reforming were 860 °C temperature (maximum tested), 0.12 mols/min glycerol flow per kg of catalyst and 2.5 steam/carbon ratio. Reforming catalysts lasted for several days of continuous operation with minimal degradation, 0.4% of feed deposited. By-product glycerol performed slightly worse with a lower yield and more carbon deposition, 2% of feed. The results show that glycerol steam reforming is a viable alternative use for glycerol and potentially a better option than purification.     

Effect of Pt and Sn on the adsorption of n-heptane in γ-Al2O3 catalyst models

The Grand Canonical Monte-Carlo (GCMC) method has been used to carry out simulations of the adsorption of n-heptane in models of naphtha-reforming catalysts. Models used in the study differed in the number and distribution of metal atoms—Pt and Sn. The number of adsorbed n-heptane molecules grows linearly with increasing number of metal atoms. The effect of Pt content on the adsorption of n-heptane molecules is most distinct at approximately 100 kPa and within the lower range of the temperatures investigated. In the models of bimetallic catalysts, the effect of the two metals is additive.Figure Effect of Pt and Sn on number of n-heptane molecules adsorbed in Al₂O₃ catalyst in 773 K and 1000 kPa.      

Effects of the reforming reagents and fuel species on tar reforming reaction

In this study, using wood chips and polyethylene (PE) as fuels, the effects of air and/or steam as reagents on the tar reforming were clarified quantitatively with a simulated gasifier/reformer apparatus of a two-staged gasification process. The results show that when only steam or air was supplied into the reformer, the tar residual rate (defined as the ratio of the tar amount in the reformed gas to the tar amount in the pyrolysis gas) and the carbon particulate concentration in both reformed gases produced from pyrolysis gases of wood chips and PE decreased with the increase of the steam ratio (H₂O/C, 0–1.0) or the air ratio (ER, 0–0.30). Supplying steam into the reformer to suppress carbon particulate formation for PE pyrolysis gas is more effective than for wood chips pyrolysis gas. Comparing with the results of steam only reforming, the effect of air supply on reduction of the tar residual rate was more significant, while that on suppression of carbon particulate formation was smaller.