The ethanol steam reforming reaction, together with the adsorption and decomposition of ethanol was studied on CeO 2 and gallium-doped ceria (CeGaO x) by a combined experimental and theoretical approach using infrared spectroscopy (IR), mass spectrometry (MS) and density functional theory (DFT) calculations. At 100°C, different types of monodentate ethoxy species were identified as standing-up (SU) on Ce 4+ and lying-down (LD) on Ce 4+ and Ga 3+ , with the alkyl chain more perpendicular or parallel to the surface, respectively. It is suggested that the incorporation of Ga into the ceria lattice changes the decomposition pathway of LD species, which converts to acetate instead of ethylene, attributed to the increased lattice oxygen lability in the CeOGa interface upon doping and the propensity to form GaH surface species. Under ethanol steam reforming conditions, Ga doping of ceriabased materials has a drastic effect by improving the H 2 :CO 2 ratio, changing the product distribution and reducing coke formation.

Introduction:Coke formation continues to be an important challenge for Pt-based catalysts during propane dehydrogenation (PDH) . Boron promotion drastically reduces coke formation on nickel during steam reforming and on cobalt during Fischer-Tropsch synthesis. DFT calculations and catalyst characterization indicate that reduced boron atoms selectively block step and/or subsurface sites, thus preventing nucleation and growth of deactivating carbon .In this work, boron is introduced to enhance the catalytic performance of Pt/γ-Al O catalysts during PDH. A series of catalysts with different boron loadings was prepared following various impregnation sequences. Detailed characterization and DFT calculations help identify boron's location and state (alloy/amorphous oxide). Results: XB-γ-Al O support materials (X=wt.%B) were prepared via wet impregnation of H BO onto commercial γ-Al O . Three different synthesis routes were followed: (a) Pt/XB-γ-Al O catalysts were prepared via wet impregnation of H PtCl onto XB-γ-Al O . (b) 1B/Pt-γ-Al O was prepared via wet impregnation of H BO onto Pt/γ-Al O i.e., an inverse sequential impregnation. (c) Pt-1B-γ-Al O was prepared by co-impregnation. Pt/γ-Al O was prepared as a reference. The platinum loading was fixed at 3wt.% to facilitate characterization and obtain B/Pt (mol) ratios from 1-10.Effects of boron loading and impregnation sequence were investigated during short-term (20 min) PDH tests at 600 C and a C H /H ratio of one. Unlike with nickel and cobalt, the promoting effect of boron was only observed when boron was introduced before the active metal. The Pt/1B-γ-Al O catalyst showed only a minor reduction in activity during the short-term experiment but achieved a 2.6-fold reduction in the amount of deposited carbon for an optimal loading of 1wt.% B. Long-term experiments (12 hr) confirmed the improved stability and selectivity of Pt/1B-γ-Al O , (Fig. 1a) with a 3.2-fold reduction in deposited carbon and an increase in propylene selectivity from 92 to 98%. TPO-profiles (Fig. 1b) of spent catalysts show that boron promotion eliminates and reduces the low-and high-temperature carbon oxidation peaks, respectively. Propylene decomposition experiments on pure and boron-modified γ-Al O relate the low-temperature peak to carbon formed on the support.