Selective hydrogenation: Encapsulated Pt@SOD catalyst exhibited 100 % selectivity in hydrogenation of p-chloronitrobenzene to p-chloroaniline via the discrimination of the hydrogenation rate of separated nitro group and separated C−Cl group during the hydrogen spillover process.

Abstract

Herein, we reported that the platinum (Pt) clusters encapsulated into sodalite (SOD) zeolite as catalyst exhibited 100 % selectivity at 100 % conversion in the selective hydrogenation of p-chloronitrobenzene to p-chloroaniline via hydrogen spillover. The direct interaction between p-chloronitrobenzene and encapsulated Pt was prevented by the shape selectivity of SOD zeolite, reactants were thereby adsorbed onto zeolite outer surface to facilitate the hydrogenation proceeding by hydrogen spillover process. The further kinetic study and DFT calculation showed the excellent catalytic selectivity was ascribed to the much faster rate of hydrogenation of adsorbed nitro group than that of adsorbed C−Cl group.

CO₂ Reforming: Transition metal-based SiO₂-Ni@CeO₂ catalyst with typical core@shell structure exhibited the better activity/stability in CO₂ reforming with ethanol reaction compared to SiO₂-Cu@CeO₂ sample.

Abstract

It is of great significance to design the high-performance catalysts with good anti-sintering and coke-resistance properties which can efficiently convert undesirable greenhouse gas CO₂ with bio-ethanol into high value-added syngas. To be addressed this issue, a series of SiO₂-M@CeO₂ (M: Cu, Ni) catalysts with typical core@shell structure were prepared via a strong electrostatic adsorption technique. Interestingly, Ni-based catalyst exhibited the higher activity towards ethanol dry reforming at the relatively low temperature. Meanwhile, SiO₂-Ni@CeO₂ catalyst presented good stability after a 50 h tests while a serious deactivation occurred for SiO₂-Cu@CeO₂ within 20 h reaction due to heavy carbon deposition and reactor blockage. Herein, the higher catalytic performance of SiO₂-Ni@CeO₂ catalyst compared to SiO₂-Cu@CeO₂ sample was attributed to the combination effect of its mesoporous structure, higher Ni dispersion as well as stronger Ni-Ce interaction as depicted by BET, TEM, XPS, H₂-TPR and XRD findings. This work might provide meaningful information to other reforming processes involving coke formation and active metal sintering problems.

The Front Cover illustrates a tug-of-war played between two concomitant but opposite effects brought forth by the presence of H₂O in the Reduction Half-Cycle (RHC) of NH₃-SCR, leading to a reduction in both the rate and its apparent activation energy with respect to dry conditions. In their Research Article, M. Maestri, E. Tronconi and co-workers show that such phenomena are a consequence of enthalpic stabilization and additional entropic penalties of the TS brought forth by the presence of H₂O in the cage of Cu-CHA. This result thus provides a theoretical understanding of the kinetic role of H₂O in the RHC, highlighting the importance of the molecular scale description of the reaction environment in voids of molecular dimensions. Image credit: Gabriele Contaldo and Lia Tagliavini. More information can be found in the Research Article by M. Maestri, E. Tronconi and co-workers.