Mingwu Tan

Solvent-Free Selective Hydrogenation of Nitroarenes Using Nanoclusters of Palladium Supported on Nitrogen-Doped Ordered Mesoporous Carbon

The selective hydrogenation of nitroarenes is a key transformation for the production of aromatic amines, which are primary intermediates in the synthesis of pharmaceuticals, agrochemicals, and dyes. However, most reaction processes require toxic organic solvents and suffer from poor selectivity in the presence of other reducible groups. Herein, we report a successful example of nanoclusters of ultrafine Pd supported on N‐modified ordered mesoporous CMK‐3 carbon (Pd/N‐CMK‐3) prepared by a facile two‐step impregnation route with aqueous solutions of 1,10‐phenanthroline and H2PdCl4 that hydrogenated various nitroarenes highly efficiently and selectively to the corresponding aromatic amines with hydrogen in the absence of solvent. The Pd/N‐CMK‐3 catalyst could be recovered easily for multiple recycling reactions without a loss of catalytic performance.

Influence of nickel content on structural and surface properties, reducibility and catalytic behavior of mesoporous γ-alumina-supported Ni–Mg oxides for pre-reforming of liquefied petroleum gas

Mesoporous γ-alumina-supported Ni–Mg oxides (xNiO–MgO/γ-MA) with various mass percentage contents of nickel (x = 0, 5, 10, 15, 18 and 21) were prepared through one-pot hydrolysis of metal nitrate salts without surfactants. The influences of nickel content on the catalyst structure, surface properties, interaction between Ni species and the support, reducibility of Ni2+ ions and Ni particle dispersion were investigated in detail using XRD, N2 sorption, TEM, XPS, CO2-TPD, H2-TPR, hydrogen chemisorption and TG techniques. The xNiO–MgO/γ-MA materials showed wormhole-like mesoporous structures with large surface areas and narrow pore size distributions. The dominant NiO species were homogeneously dispersed and had an attenuated interaction with the support with the increase in Ni content, producing uniform Ni nanoparticles throughout γ-alumina frameworks after H2 reduction. The Ni particle sizes decreased with increasing Ni content and showed a minimum at 18 wt%, likely due to Ni crystallite growth by Ostwald ripening rather than by migration of Ni nanoparticles. The reduced xNi–MgO/γ-MA catalysts were investigated for their catalytic behaviors in pre-reforming of liquefied petroleum gas. The results demonstrated that the Ni surface areas were mainly responsible for their catalytic activities; smaller Ni nanoparticles promoted steam reforming of hydrocarbons, methanation of carbon oxides and water gas shift reaction, but inhibited hydrocracking of hydrocarbons and lowered the rate of coke deposition, improving the catalytic activity and stability.

Perovskite LaNiO3 Nanocrystals inside SBA-15 Silica: High Stability and Anti-Coking Performance in the Pre-Reforming of Liquefied Petroleum Gas at a Low Steam-to-Carbon Molar Ratio

A high loading of LaNiO3 perovskite nanocrystals (83 wt %) was successfully incorporated inside the ordered mesoporous framework of SBA‐15 silica by a citric acid assisted impregnation method. The obtained LaNiO3/SBA‐15 material produced both La2O3 nanoparticles and metal Ni nanoparticles with intimate contact and highly dispersed in the mesoporous SBA‐15 framework upon reduction with H2, and it showed high activity, high stability, and good anti‐coking ability for the low‐temperature steam reforming of liquefied petroleum gas at a low steam/carbon ratio of 1.0. The excellent performance of the LaNiO3/SBA‐15 material was attributed to the formation of synergistic active sites in the interfacial area, which consisted of metal Ni and La2O2CO3 species, and the confinement effect of the mesoporous structure on the Ni and La2O3 species.