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Nitrobenzene liquid-phase catalytic hydrogenation is commonly regarded as one of the most effective technologies for aniline production. The traditional granular catalysts have the disadvantages that the reactor bed pressure drop is large and the mass transfer efficiency between gas and liquid phases is low. In this study, a novel structured mesh-type Pd/γ-Al2O3/Al catalyst was prepared by anodic oxidation and pore structures of γ-Al2O3/Al supports were constructed by acid pore-widening treatments. The results showed that acid pore-widening treatments can improve the pore size of γ-Al2O3/Al supports; the support with HNO3 pore-widening treatment exhibited the largest pore size, being enlarged from 3.7 nm to 4.6 nm. The Pd/γ-Al2O3/Al catalysts prepared with different acid pore-widening treatment supports contribute to the increased active metal Pd loading, more Pd0 content, and better dispersion of the Pd particles. The catalyst prepared with HNO3 pore-widening treatment support exhibited the largest active metal Pd loading, enlarging from 1.82% to 1.95%, the largest Pd0 content being enlarged from 52.1% to 58.5% and the smallest Pd particle size being reduced from 103 nm to 41 nm, resulting in the highest nitrobenzene conversion, increasing from 67.2% to 74.3%. Eventually, we calculated that the pressure drop of structured catalysts was 1/72 of that of granular catalysts, resulting in a better diffusion of the H2 through nitrobenzene solution to active sites on the catalyst surface and a significant increase in the catalytic activity. [ABSTRACT FROM AUTHOR]

A structured anodic alumina-supported Pt and Fe composition catalyst was developed to investigate its catalytic performance in carbon monoxide (CO) oxidation reactions. It is found that the hydroxyl-rich structured Pt/Fex/γ-Al2O3/Al catalyst with a mass of 0.58 g achieved 100% removal of CO and exhibited good stability of 60 h by weakening the competition between CO and O2 on the catalyst and decreasing the energy barrier. In addition, a series of explorations were carried out on the changes of relevant functional groups and active sites during catalyst deactivation and regeneration, and the data were explained in detail. Furtherly, it is demonstrated by in situ DRIFT that formate species are the important intermediates, produced by the reaction between hydroxyl group (–OH) on the catalyst and adsorbed CO. To explore the reaction mechanism at the atomic level, the CO oxidation reaction at the interface of Pt, Pt–OH, and Pt–Fe2O3 was analyzed by DFT calculations. [ABSTRACT FROM AUTHOR]

Palladium‐based catalysts have been widely employed in the electro‐Fenton process for in situ generation of H2O2. However, the process is still far from being practical on a large scale. In this work, a series of ClxFePd/γ‐Al2O3/Al catalysts were prepared by a three‐step‐impregnation method. They exhibited excellent activity in H2O2in situ synthesis and high efficiency in phenol degradation. The characterization results showed that Cl could assist in increasing the content of Pd0 and reducing the isoelectric point of catalysts, which led to the drastic promotion in the synthesis of H2O2. Theoretical calculations further demonstrated that Cl doping could facilitate the main reaction in H2O2 synthesis, as well as inhibit side reactions such as dissociation of the OO bond. Furthermore, kinetic models were proposed and fitted. A plausible reaction mechanism as well as degradation pathways were elaborated based on electron spin resonance and gas chromatography–mass spectrometry results. These findings illustrate the value of palladium‐based ClxFePd/γ‐Al2O3/Al catalysts for their application in the electro‐Fenton process. [ABSTRACT FROM AUTHOR]