Several TiO₂ based semiconductors with different Pt loadings are prepared using incipient impregnation, wet impregnation and the sol-gel method. These photocatalysts are evaluated in the Photo-CREC-Water II Photoreactor for hydrogen production via water dissociation, using an organic renewable scavenger (ethanol). Results obtained show the influence of the photocatalyst preparation in the production of hydrogen and in the observed quantum yields. Furthermore, it is established that the reaction networks leading to hydrogen production, using various photocatalysts, share common features. This analysis is developed by both identifying and quantifying different chemical species and their changes with irradiation time. Key species in this oxidation–reduction network are hydrogen, hydrogen peroxide, ethanol, methane, ethane, acetaldehyde and carbon dioxide. On this basis, it is shown that under an inert gas atmosphere, ethanol consumption is sub-stoichiometric. This points towards simultaneous ethanol consumption and the formation of the ethanol scavenger.

Fluidizable catalysts based on Ni/Al₂O₃ with added Ru were used for the gasification of a lignin surrogate (2-methoxy-4-methylphenol) in a fluidized CREC Riser Simulator reactor. This was done in order to quantify lignin surrogate conversion and lignin surrogate products (H₂, CO, CO₂ and CH₄) as well as the coke deposited on the catalyst. The catalysts that were evaluated contained 5% wt. Ni with various Ru loadings (0.25%, 0.5% and 1% wt). These catalysts were synthesized using an incipient Ni and Ru co-impregnation. Catalysts were characterized using XRD, N₂ adsorption-desorption (BET Surface Area, BJH), Temperature Programmed Reduction (TPR), Temperature Programmed Desorption (TPD) and H₂ chemisorption. Catalytic steam gasification took place at 550, 600 and 650 °C using 0.5, 1.0 and 1.5, steam/biomass ratios. The results obtained showed that Ru addition helped to decrease both nickel crystallite site sizes and catalyst acid site density. Moreover, it was observed that coke on the catalyst was reduced by 60%. This was the case when compared to the runs with the Ni/Al₂O₃ free of Ru.

Nickel on alumina support offers opportunity for gasification of biomass for hydrogen production. In a recent contribution from our research team, (González Castañeda, D. G., et al. 2019) showed that cerium or lanthanum co-impregnation at 2 wt% with nickel may have a favorable effect for biomass catalytic gasification. However, and given an observed influence of lanthanum on the formation of small Ni crystallite sizes, five Ni/γ-Al₂O₃ based fluidizable La promoted catalysts were studied. Nickel-alumina catalysts promotion was effected varying La in the 0.5 and 1.0 wt% range. Once impregnation precursors loaded, they were reduced at 480 °C via an activation step. Catalysts were characterized using BET, XRD, AA, TPR, TPD, H₂-chemisorption, TEM-EDX and FTIR. Catalyst performance was established in a fluidized CREC Riser Simulator, using: a) glucose as surrogate biomass, b) 600 °C, c) steam/biomass (S/B) ratio of 1, d) catalyst /biomass (C/B) ratio of 3.2 and e) 20 s reaction time. Data obtained was analyzed using an ANOVA statistical data analysis package with the 5 wt% Ni and 0.5–1 wt% La and Ce on γ-Al₂O₃ catalysts, prepared using a pH of 1 of impregnating solution were the best yielding 0.53–0.56 hydrogen molar fractions. These catalysts also gave a 39% reduced coke, and this while compared with the coke formed on the 2% Ce – 5 wt%Ni/γ-Al₂O₃ (González Castañeda, D. G., et al. 2019). This promising performance was assigned to the dominant NH₃-TPD medium acidity, the high catalyst specific surface (∼140 m²/g), and the good 9% metal dispersion with 9–10 nm nickel crystallites.

Hydrogen is an energy vector with a great potential due its ample range of applications and clean combustion cycle. Hydrogen can be produced through biomass steam gasification, with novel catalysts being of significant value to implement this process. With this goal in mind, in the present study, 5 wt % Ni/γAl₂O₃ promoted with 0.25 wt % Ru was synthesized and characterized. It is assumed that ruthenium facilitates hydrogen transfer to nickel oxide sites, promoting a hydrogen spillover effect, with the H₂ adsorbed on Ru being transported to Ni sites. To describe chemical changes, the present study considers a kinetic model involving Langmuir–Hinshelwood-based rate equations, as a sum of independent reactions, with this being applied to the steam gasification of 2-methoxy-4-methylphenol (2M4MP). This tar biomass surrogate was studied in a fluidized CREC (Chemical Reactor Engineering Centre) Riser Simulator reactor, at different reaction times (5, 20 and 30 s.) and temperatures (550 °C, 600 °C and 650 °C). The proposed kinetics model was fitted to the experimentally observed H₂, CO₂, CO, CH₄ and H₂O concentrations, with the estimated pre-exponential factors and activation energies being in accordance with the reported literature data. It is anticipated that the postulated model could be of significant value for the modeling of other biomass conversion processes for hydrogen production using other supported catalysts.