The reaction mechanism of reverse water-gas shift (RWGS) reaction was investigated using two commercial gold-based catalysts supported on Al2O3 and TiO2. The surface species formed during the reaction and reaction mechanisms were elucidated by transient and steady-state operando DRIFTS studies. It was revealed that RWGS reaction over Au/Al2O3 proceeds through the formation of formate intermediates that are reduced to CO. In the case of Au/TiO2 catalyst, the reaction goes through a redox mechanism with the suggested formation of hydroxycarbonyl intermediates, which further decompose to CO and water. The Ti 3+ species, the surface hydroxyls, 2 and oxygen vacancies jointly participate. The absence of carbonyl species adsorbed on gold particles during the reaction for both catalysts indicates that the reaction pathway involving dissociative adsorption of CO2 on Au particles can be discarded. To complete the study Operando UV-Vis spectroscopy was successfully applied to confirm the presence of Ti 3+ and to understand the role of the oxygen vacancies of TiO2 support in activating CO2 and thus the subsequent RWGS reaction.

Albeit a variety of available strategies for CO 2 conversion to useful chemicals and fuels, most technologies require relatively pure CO 2 , especially without oxygen and water.This requires additional steps of CO 2 capture and purification before its efficient conversion. This necessity increases energy requirement, leading to poorer carbon footprints and higher capital expenditures lowering the viability of overall CO 2 conversion processes. We have developed an effective technology which combines CO 2 capture and conversion processes using isothermal unsteady-state operation and a catalyst consisting of earth-abundant chemical elements (FeCrCu/K/MgO-Al 2 O 3 ).Diluted CO 2 streams common in process flue gases, even containing oxygen and water, can be fed to the process and relatively pure product stream such as syngas, i.e. carbon oxides (CO and CO 2 ) and hydrogen mixture, can be produced. A possible scheme of reactor integration for continuous CO 2 abatement and conversion based on a tworeactors system is presented.

The effect of the magnesia loading on the surface structure and catalytic properties of NiSn/MgO-Al2O3 catalysts for hydrogen production by methanol steam reforming has been investigated. The catalysts have been obtained by impregnation of γ-Al2O3 by the incipient wetness method, with variation of the MgO content. X-ray diffraction (XRD), BET surface area and H2-temperature programmed reduction (TPR) have been used to characterise the prepared catalysts. From this, it has been concluded that the incorporation of MgO results in the formation of MgAl2O4 spinel, which modifies the acid-base properties of the catalysts. The formation of Ni-Sn alloys after the reductive pre-treatment has also been evidenced.The influence of the temperature of reaction and of the MgO loading on the hydrogen production by reforming of methanol has been established. Moreover, tests of catalytic stability have been carried out for more than 20 h. The carbonaceous deposits have been examined by temperature-programmed oxidation (TPO). The analysis of the catalysts after reaction has confirmed the low level of carbon formation on these catalysts. In no case, carbon nanotubes have been detected on the solids.

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