With demand for gasoline and diesel expected to decline in the near future, crude-tochemicals technologies have the potential to become the most important processes in the petrochemical industry. This trend has triggered intense research into the optimization of current refining processes to maximize the production of light olefins and aromatics at the expense of fuels. Although attractive, this approach has shown certain limitations and calls for disruptive processes able to directly transform crude to chemicals in a more efficient and environmentally friendly way. Here we propose a new reactor concept consisting of a multi-zone fluidized bed (MZFB) along with a new catalyst formulation able to perform several refining steps in one single reactor vessel. The MZFB configuration allows for in situ catalyst stripping and regeneration, while the incorporation of silicon carbide during catalyst shaping via spray drying confers this new catalyst formulation with improved physical, mechanical and heat transport properties. As a result, we demonstrate that, using this reactor-catalyst combination, it is possible to achieve stable direct

NiO and metal-promoted NiO catalysts (M-NiO, with a M/(M+Ni) atomic ratio of 0.08, with M = Nb, Sn, or La) have been prepared, tested in the oxidative dehydrogenation (ODH) of ethane, and characterized by means of XRD, TPR, HRTEM, Raman, XPS, and in situ XAS (using H2/He, air or C2H6/He mixtures). The selectivity to ethylene during the ODH of ethane decreases according to the following trend: Nb–NiO ≈ Sn–NiO > La–NiO > NiO, whereas the catalyst reducibility (determined by both TPR and XAS using H2/He mixtures) shows the opposite trend. However, different reducibility and catalytic behavior in the absence of oxygen (ethane/He mixtures) have been observed, especially when comparing Nb- and Sn-promoted NiO samples. These differences can be ascribed mainly to a different phase distribution of the promoter. The results presented here are discussed in terms of the nature of active and selective sites for ODH of ethane in selective and unselective catalysts, but also the role of promoters and the importance of their phase distribution.

The conversion of CO2 to light olefins via bifunctional catalysts (i.e. metal oxides/zeolites) is a promising approach to tackle CO2 emissions and, at the same time, reduce fossil-fuel dependence by closing the carbon cycle.

Two cobalt catalysts, Co/SBA-15 and Co/SiO2, have been studied in steam reforming of ethanol (SRE). Besides the steam reforming products, ethoxide dehydrogenation to acetaldehyde is observed as one of the main reactions. Although by hydrogen treatment cobalt is reduced to the metallic state, under SRE conditions, a phase appears that has been identified as cobalt carbide and correlates with acetaldehyde production. These findings provide insights about the catalytic sites, for SRE, in cobalt catalysts. Comparison with previous results shows that these conclusions are not translatable to other cobalt catalysts, stressing the importance of the support on the catalytic behavior of cobalt.

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A series of four Ni catalysts supported on SBA-15 and on a high SiO surface area have been prepared by modified impregnation (ImU) and deposition-precipitation (DP) methods. The catalysts have been extensively characterized, including in situ XAS (bulk sensitive) and XPS (surface sensitive) techniques, and their catalytic activities evaluated in the dry reforming reaction of methane (DRM). The combined use of XPS and XAS has allowed us to determine the location of nickel particles on each catalyst after reduction at high temperature (750 °C). Both Ni/SiO-DP and Ni/SBA-15-DP catalysts yield well-dispersed and homogeneous metallic phases mainly located in the mesoporosity of both supports. On the contrary, the Ni/SiO-ImU and Ni/SBA-15-ImU catalysts present a bimodal distribution of the reduced nickel phase, with nickel metallic particles located out and into the mesoporous structure of SiO or the SBA-15 channels. The Ni/SBA-15-DP catalyst was found the most stable and performing system, with a very low level of carbon deposition, about an order of magnitude lower than the equivalent ImU catalyst. This outstanding performance comes from the confinement of small and homogeneous nickel particles in the mesoporous channels of SBA-15, which, in strong interaction with the support, are resistant to sintering and coke deposition during the demanding reaction conditions of DRM.

Two different nickel supported on SBA‐15 catalytic systems have been prepared by means of impregnation (Ni/SBA‐15‐ImU) and deposition‐precipitation (Ni/SBA‐15‐DP) methodologies. Upon calcination, Ni/SBA‐15DP presents a well‐developed nickel phyllosilicate phase, which after reduction gives rise to a dispersed and homogeneous metallic phase, mainly located inside the 5 nm in diameter mesoporous structure of the support. On the contrary, as evidenced by XRD and a double temperature programmed reduction (TPR) peak, the Ni/SBA‐15‐ImU catalyst presents two different NiO phases, which after reduction in hydrogen generate nickel particles in a wide range of sizes. In situ XAS and XPS have unambiguously showed that the distinct TPR profiles obtained for each system are related with particles located in and out the mesoporous structure of the SBA‐15 channels. The particles inside the porous are more difficult to reduce, clearly showing a kind of confinement effect of the SBA‐15 mesostructure, modifying the reducibility of the NiO phase.

We investigate the use of a series of iron-based metal−organic frameworks as precursors for the manufacturing of isobutane dehydrogenation catalysts. Both the as-prepared and spent catalysts were characterized by PXRD, XPS, PDF, ICP-OES, and CHNS+O to determine the physicochemical properties of the materials and the active phases responsible for the catalytic activity. In contrast to the previous literature, our results indicate that (i) the formation of metallic Fe under reaction conditions results in secondary cracking and coke formation; (ii) the formation of iron carbide only contributes to coke formation; and (iii) the stabilization of the Fe 2+ species is paramount to achieve stable and selective catalysts. In this sense, promotion with potassium and incorporation of titanium improve the catalytic performance. While potassium is well known to improve the selectivity in iron-catalyzed dehydrogenation reactions, the unprecedented effect of titanium in the stabilization of a nanometric titanomaghemite phase, even under reductive reaction conditions, results in a moderately active and highly selective catalyst for several hours on stream with a remarkable resistance to coke formation.