Dry reforming of methane is gaining great interest owing to the fact that this process efficiently converts two greenhouse gases (CH 4 and CO 2 ) into synthesis gas (CO + H 2 ), which can be further processed into liquid fuels and chemicals. Herein, a perovskite-derived nanostructured Ni/La 2 O 3 material is reported as an efficient and stable catalyst for this reaction. High-surface-area LaNiO 3 perovskite precursor is first synthesized by the method of nanocasting using ordered mesoporous silica SBA-15 as a hard template. The resulting nanostructured perovskite was found to possess high specific surface area as obtained from the BET method (150 m 2 g −1 ). The reduction behavior of the nanocast perovskite was monitored by performing the temperature-programmed reduction of hydrogen (TPR-H 2 ). It has been found that the complete destruction of perovskite structure occurs below 700 °C, leading to the formation of highly dispersed Ni 0 in La 2 O 3 , as observed in the XRD pattern of the material after reduction. Similar behavior was observed for the LaNiO 3 perovskite synthesized using the conventional citrate process. However, the specific surface area of the former material was found to be much higher than that of the latter (50 m 2 g −1 ), which obviously resulted from the mesoporous architecture of the nanocast LaNiO 3 . It was found that the nanostructured Ni/La 2 O 3 obtained from the reduction of the nanocast LaNiO 3 exhibited high activity for the conversion of the reactant gases (CH 4 and CO 2 ) compared to the catalyst obtained from conventional perovskite, under the reaction conditions used in the present study. Particularly, no coke formation was observed for the mesoporous catalyst under the present conditions of operation, which in turn reflects the enhanced stability of the catalyst obtained from the nanocast LaNiO 3 . The improved performance of the nanostructured catalyst is attributed to the accessibility of the active sites resulting from the high specific surface area and the confinement effect leading to the stabilization of Ni nanoparticles.
Perovskites and parent Ruddlesden–Popper structures were proved to be suitable redox materials for two-step solar thermochemical CO2 splitting.
We propose large‐pore titanium‐containing organosilylated mesoporous silica (Ti‐SBA‐15) as a highly efficient catalyst for the oxidative desulfurization (ODS) of refractory aromatic sulfur compounds with the aim to produce ultra‐low sulfur diesel. To achieve this, we synthesized a series of mesoporous Ti‐SBA‐15 catalysts according to a new procedure. The procedure is based on the controlled grafting of titanium chelates on SBA‐15 silica at low temperatures (5 °C). This specific synthesis procedure ensured a high dispersion of the required 4‐coordinate tetrahedral Ti4+ sites located on the mesopore surface. To substantiate the influence of the titanium content and mesopore size on the ODS performance of the catalysts, the parameters were varied in the range of 0.7 to 4.7 mol % (Si/Ti) and 5.1 to 9.0 nm, respectively. The resulting Ti‐SBA‐15 catalysts were then tested in the oxidative desulfurization (ODS) of model sulfur‐containing compounds in the presence of cumene hydroperoxide (CHP) as the organic oxidant. The ODS of a real industrial diesel fuel was also carried out in a continuous fixed bed reactor with the same Ti‐SBA‐15 catalysts and CHP. The catalytic results revealed that the Ti‐SBA‐15 catalysts with the largest pore sizes (>7.3 nm) and highest Ti contents (>2.8 mol %) were highly active catalysts for ODS reactions. Moreover, the catalysts with large pores and high Ti loadings appeared to be stable for over 30 h and were far less prone to deactivation than their equivalent Ti‐SBA‐15 samples with smaller pore diameters and lower Ti contents.
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