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This paper is focused on the photocatalytic hydrogen production on Pd/TiO2(-WO3) catalysts from water-methanol and water-glycerol mixtures under UVA and solar irradiation. The photodeposition method for Pd was studied varying conditions such as Pd amount, catalyst concentration and methanol concentration. The catalysts were tested at lab scale under simulated solar light and UVA radiation and also at large scale (25 L) under solar energy using a pilot-scale solar Compound Parabolic Collector (CPC). The catalysts characterization was performed by means of ICP-OES, N2 adsorption–desorption isotherms, XRD, HR-TEM, XPS and DR–UV–Vis spectroscopy. Hydrogen evolution was monitored by on-line gas chromatography.From results it was found the Pd photodeposition method plays a key role to increase the hydrogen evolution, affecting parameters like the Pd amount deposited, the Pd nanoparticles size and dispersion. The highest quantum efficiency (¿) obtained in this study was 11.8% and 41.2% under simulated solar and UVA irradiation, respectively, using Pd(0.24 wt%)/P25 in an aqueous solution of methanol (50 vol%). In the pilot-scale solar CPC, for Pd(0.24 wt%)//P25 catalysts in 5 vol% of methanol or glycerol as sacrificial agents, the quantum yield were 2.1 and 2.2%, respectively. When the concentration of the sacrificial agents decreased to 0.37 vol%, the quantum yields were 1.3 and 2.4% for methanol and glycerol, respectively. Compared to literature, the low noble metal content of these catalysts (0.25 wt%) seems to be a competitive factor considering their high price.

Ceria-supported Ni, Ru and Ni Ru catalysts have been tested in the catalytic decomposition of ammonia to yield hydrogen and their performance in long-term tests has been compared to alumina-supported Ni and Ru samples. The catalysts have been characterized by XRD, TPR, NH3-TPD, HAADF-STEM, SEM, BET and XPS. Ceria-based samples are more active in ammonia decomposition with respect to their alumina-based counterparts, which has been ascribed to a particular metal-support interaction, while acidity does not seem to play an important role. Ru-based catalysts are more active than Ni-based samples, but they deactivate rapidly, in particular the Ru/Al2O3 sample. This is ascribed to loss of exposed Ru, as demonstrated by XPS and HAADF-STEM. Considering the high cost and limited availability of Ru, the Ni/CeO2 catalyst appears as a promising system for ammonia decomposition due to its good performance and low cost. In situ XPS experiments reveal that the active sites for the catalytic decomposition of ammonia are metallic Ni and Ru. Bimetallic Ni Ru catalysts do not outperform their monometallic counterparts, irrespective of the order in which the metals are added.

This paper focuses on the dynamic modelling and the predictive control of an ethanol steam reformer (ESR) with Pd[sbnd]Ag membrane separation stage for the generation of pure hydrogen. Hydrogen purity necessary to feed a proton exchange membrane fuel cell (PEMFC) is required. A non-linear dynamic model of the ESR is developed together with a procedure for adjusting the model parameters in order to fit a bank of experimental data of a real ESR system. Static and dynamic analysis of the non-linear ESR model is presented. From this non-linear model, a linear, reduced order and discretised model is derived and a model predictive controller (LMPC) is designed for the ESR system. Control objectives are pure hydrogen flowrate tracking and ethanol inlet minimization. Comparisons between the non-linear and linear models are carried out to determine the control constraints. Finally, simulation results for the implemented LMPC controller are presented and discussed., This paper has been partially supported by Spanish research projects. DPI2015-69286-C3-2-R, MINECO/FEDER and ENE2015-63969-R, MINECO/FEDER. Mingming Li has been supported by the China Scholarship Council (CSC). Jordi Llorca is Serra Húnter Fellow and is grateful to ICREA Academia program.

A series of ceria-zirconia solid solutions has been prepared by a surfactant assisted coprecipitation method. After impregnation of copper, their activities have been assessed for methanol steam reforming. The results indicate that the compositions with 10 and 15 at.% loading of copper on Ce0.6Zr0.4O2 exhibit maximum catalytic efficiency. Detailed structural analyses reveal high degree of copper dispersion on the ceria-zirconia matrix. In situ XPS studies confirm reduction of surface CuO species with concomitant lowering of Cu-surface atomic composition and increase of carbon. These evidences point to the formation of large aggregates of copper covered with coke that is suggested to be responsible for on stream activity loss. On regeneration, these aggregates break into a mixture of oxidized (Cu2+) and reduced (Cu-o and Cu+) copper species showing similar activity to the as prepared catalysts. In general, we have attributed catalytic activity to different proportions of copper components in the various forms of these catalysts. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.