Palladium nanoparticles (Pd NPs) were synthesised by the reduction-by-solvent method using polyvinylpirrolidone (PVP) as capping agent. The non-static interaction between PVP and the metallic surface may change the properties of the NPs due to the different possible interactions, either through the O or N atoms of the PVP. In order to analyse these effects and their repercussion in their catalytic performance, Pd NPs with various PVP/Pd molar ratios (1, 10 and 20) were prepared, deposited on silica and tested in the formic acid decomposition reaction. The catalytic tests were conducted using catalysts prepared by loading NPs with three different time lapses between their purification and their deposition on the silica support (1 day, 1 month, and 6 months). CO adsorption, FTIR spectroscopy, XPS and TEM characterisation were used to determine the accessibility of the Pd NPs surface sites, electronic state of Pd and the average NPs size, respectively. The H 2 production from the formic acid decomposition reaction has a strong dependence with the Pd surface features, which in turn are related to the NPs aging time due to the progressive removal of the PVP.

Highlights  CoOx-N nanoparticles loaded on CNTs are prepared by a simple procedure  CoOx loading/nanoparticle size affects the electrocatalytic behaviour  ORR activity is very much influenced by the N content in the electrocatalyst  C-N-Co interactions are quite important for the remarkable electrocatalytic activity  No significant deactivation is observed after MeOH addition with only 1 wt. % of Co

Pd and bimetallic Ni 50 Pd 50 nanoparticles protected by polyvinylpyrrolidone (PVP) have been synthesized by the reduction-by-solvent method and deposited on single wall carbon nanotubes (SWCNTs) to be tested as H 2 sensors. The SWCNTs were deposited by drop casting from different suspensions. The Pd nanoparticles-based sensors show a very reproducible performance with good sensitivity and very low response times (few seconds) for different H 2 concentrations, ranging from 0.2 to 5 % vol. H 2 in air at atmospheric pressure. The influence of the metal nanoparticle composition, the quality of SWCNTs suspension and the metal loading have been studied, observing that all these parameters play an important role in the H 2 sensor performance. Evidence for water formation during the H 2 detection on Pd nanoparticles has been found, and its repercussion on the behaviour of the assembled sensors is discussed.The sensor preparation procedure detailed in this work has proven to be simple and reproducible to prepare cost-effective and highly efficient H 2 sensors that perform very well under real application conditions. * Corresponding author. Fax: +34 965 903454 E-mail: a.berenguer@ua.es (Á. Berenguer-Murcia) 2 1. Introduction.

Well dispersed iron catalysts were synthesized in silica (Fe 0.0X SiO 2 ) by a one-step synthesis procedure. These materials were tested in the propylene epoxidation reaction with gaseous O 2 . The influence of the iron metal loading on the iron incorporation and distribution in the support (both influenced by the synthetic procedure) were thoroughly studied (conversion, generation and selectivity). Electron Microscopy and UltraViolet-Visible (UV-VIS), Raman and Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy techniques were used to analyze the iron distribution in the catalysts and to probe its incorporation into the silica framework. Insitu FTIR was also used to analyze the interaction between propylene and iron-based catalysts. This is a previous version of the article published in Journal of Catalysis. 2016Catalysis. , 338: 154-167. doi:10.1016Catalysis. /j.jcat.2016 2 Computational calculations considering a single-site iron catalyst incorporated into the silica structure show a possible interaction between O 2 and the incorporated iron atom and the olefin bond and the acidic proton neighboring the iron species which favours the reaction between the two molecules near the iron atom.

Novel hierarchical SiO 2 monolithic microreactors loaded with either Pd or Pt nanoparticles have been prepared in fused silica capillaries and tested in the PreferentialOxidation of CO (PrOx) reaction. Pd and Pt nanoparticles were prepared by the reduction by solvent method and the support used was a mesoporous SiO 2 monolith prepared by a well-established sol-gel methodology. Comparison of the activity with an equivalent powder catalyst indicated that the microreactors show an enhanced catalytic behaviour (both in terms of CO conversion and selectivity) due to the superior mass and heat transfer processes that take place inside the microchannel. TOF values at low CO conversions have been found to be ~2.5 times higher in the microreactors than in the powder catalyst and the residence time seems to have a noticeable influence over the selectivity of the catalysts designed for this reaction. The Pd and Pt flexible microreactors developed in this work have proven to be effective for the CO oxidation reaction both in the presence and absence of H 2 , standing out as a very interesting and 1 Corresponding author. Fax: +34 965 903454 E-mail address: a.berenguer@ua.es (Á. Berenguer) suitable option for the development of CO purification systems of small dimensions for portable and on-board applications.