Metal organic frameworks are thoroughly reviewed as exemplary precursors for the manufacture of highly catalytically active materials.

A Co@N‐doped carbon (Co@NC) hybrid was synthesized by thermal decomposition of the metal–organic framework (MOF) ZIF‐67 under N2 atmosphere. These hybrid materials exhibit outstanding catalytic activity and chemoselectivity for the conversion of a wide range of substituted nitroarenes to their corresponding anilines under relatively mild reaction conditions. The high catalytic performance is attributed to the formation of cobalt nanoparticles and to the presence of atomically dispersed Co species in close interaction with nitrogen‐doped graphene. Both active species are formed in situ during the pyrolytic transformation of ZIF‐67. The catalysts could be reused in consecutive runs, exhibiting a slightly lower activity ascribed to blockage of the active sites by strongly adsorbed reaction species. These results open up a pathway for the design of noble‐metal‐free solid catalysts for industrial applications.

The Ti-containing metal organic framework (MOF) MIL-125 has been used as sacrificial precursor to obtain TiO2 materials through the MOF-mediated synthesis route. In this study, Fe 3+ was deposited on the surface of MIL-125 after its hydrothermal synthesis. Targeted Fe-doped titania photocatalysts were prepared through the direct calcination in air of Fe/MIL-125 crystals and/or by using a two-step method, including carbonization in inert atmosphere followed by calcination in air. The relationship between the synthesis conditions and the properties of the Fe-doped titania nanopowders, such as Fe content, porosity, phase composition and particle size was investigated.From elemental mapping, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, UV-Vis absorption spectroscopy and photoluminescence emission spectra, the presence of highly dispersed Fe 3+ ions incorporated into the TiO2 crystal lattice was confirmed, which led to a significant red shift of photoresponse towards visible light and reduced the recombination rate of electron-hole pairs at low iron content. By varying the pre-carbonization temperature, both crystal size and phase composition in the final materials were modulated. The performance of Fe-doped titania materials in photocatalytic water-splitting was tested for hydrogen evolution. Optimal photocatalytic performance was found at 0.15 and 0.5 wt. % iron concentration and exceeded those of non-doped titania and commercial anatase both under visible and UV light irradiation, respectively, and among the highest reported in literature for these systems.

Deactivation of Ni/La2O3–αAl2O3 catalyst in ethanol steam reforming (ESR) was studied in order to establish the optimal conditions for maximizing H2 production and achieving steady behavior. The ESR reactions were conducted in a fluidized bed reactor under the following operating conditions: 500–650 °C; space-time up to 0.35 gcatalyst h/gEtOH; and steam/ethanol (S/E) molar ratio in the feed, 3–9. The features of the deactivated catalysts and the nature and morphology of the coke deposited were analyzed by temperature-programmed oxidation, X-ray diffraction, scanning electron microscopy, and Raman spectroscopy. Catalyst deactivation was solely caused by coke deposition, especially by encapsulating coke, with acetaldehyde, ethylene, and ethanol being the main precursors, whose concentration was high for lower values of space-time. Conversely, the filamentous coke formed from CH4 and CO (with their highest concentration for intermediate values of space-time) had a much lower impact on deactivation. Owing to the effect of space-time on the extent of reactions leading to the formation of coke precursors, the Ni/La2O3–αAl2O3 catalyst stability was enhanced by increasing space-time. The increase in temperature and S/E ratio was also beneficial since both variables promoted coke gasification. Consequently, a steady H2 yield throughout 200 h reaction was attained at 600 °C, a space-time of 0.35 gcatalyst h/gEtOH, and S/E > 3.

The regenerability of Ni catalysts in reforming reactions is a key factor for process viability. Accordingly, this study addresses the regeneration of two spinel NiAl 2 O 4 type catalysts by reaction-regeneration cycles in the oxidative steam reforming (OSR) of raw bio-oil. The spinel type catalysts were prepared by different methods including a supported Ni/La 2 O 3 -αAl 2 O 3 catalyst and a bulk NiAl 2 O 4 catalyst. The experimental setup consists of two units connected in series for i) the thermal treatment of bio-oil at 500 ºC, in order to control the deposition of pyrolytic lignin, followed by; ii) the oxidative steam reforming (OSR) of the remaining oxygenates in a fluidized bed catalytic reactor.The conditions in the OSR reaction step were: 700 ºC; oxygen/steam/carbon ratio (O/S/C), 0.34/6/1; space time, 0.75 g catalyst h/g bio-oil (for supported catalyst) and 0.15 g catalyst h/g bio-oil (for bulk catalyst). Three different strategies have been studied in the regeneration step by coke combustion, including the in situ regeneration inside the reactor at 650 ºC and 850 ºC, and the ex situ regeneration in an external oven at 850 ºC, for 4 h in all the cases. The behavior of the fresh and regenerated catalysts has been explained according to their metallic properties, determined by different characterization techniques (temperature programmed reduction (TPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electronic microscopy (TEM)). According to these results, the combustion ex situ of the catalyst at 850 °C is able to completely regenerate the bulk catalyst, since these

The cobalt-based ZIF-67 has been evaluated for the adsorptive propylene/propane separation in a fixed bed. Characterization techniques and dynamic measurements have been performed over ZIF-67 to evaluate its potential in this defiant process. Cobalt promotes a more rigid framework than zinc in the isostructural ZIF-8. Although the adsorption affinity of ZIF-67 for both hydrocarbons is similar, the lower flexibility of the framework makes ZIF-67 behaving with a clear preference towards propane. This inverse selectivity promotes the enrichment in propylene content upon breakthrough, and may simplify the separation scheme. Therefore, ZIF-67 adsorptive separation is presented as an alternative to energy-demanding distillation.

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