Chemoselective hydrogenation of nitroarenes to anilines is of great importance for the manufacture of pharmaceuticals, fine chemicals, and dyes. In this study, a series of metal-free N-doped carbon nanotubes (NCNTs) have been prepared by the carbonization of in situ polymerized pyrrole on CNTs. The concentration of pyrrole, pyrolysis temperature, and the outside diameter of CNTs were investigated to improve the catalytic performance. As characterized by Raman and X-ray photoelectron spectroscopy (XPS), the optimal catalyst (NCNTs-800) possessed a unique structure doped with the same content of pyrrolic N and graphitic N. The activity and selectivity of NCNTs-800 have been evaluated for the selective hydrogenation of substituted nitroarenes. Highly selective hydrogenation of the nitro group of 12 different substrates has been achieved on NCNTs-800, even in the presence of a fragile iodo group. The hydrogenation reaction on N-doped CNTs from polypyrrole involved a mixture of different hydrogen species including nonpolar H radicals. In addition, stability and recyclability of NCNTs-800 have been tested.
Hexagonally ordered mesoporous MSU-S was assembled from nanoclustered zeolite seeds. The XRD and BET results verified that after treated in 10%H 2 O/N 2 atmosphere at 800°C for 2 h, MSU-S still remained a well-ordered hexagonal structure due to rich acidic sites and excellent hydrothermal stability. A series of Sm x Mn y O z /MSU-S sorbents were prepared by a sol−gel method. The desulfurization performances of the 55%Sm 5 Mn 95 /MSU-S sorbent were improved significantly due to high hydrothermal stability of MSU-S with high surface area as well as the synergistic effect between Mn and Sm 2 O 3 . The result of eight successive sulfurization/regeneration cycles of sorbent illustrated that high breakthrough sulfur capacity and endurable stability of 55%Sm 5 Mn 95 /MSU-S correlated closely with the existence of the framework 4-coordination aluminum (NH 3 -TPD, 27 Al MAS NMR) and high dispersion of Sm/Mn species on MSU-S (XRD, TPR) for H 2 S removal. HRTEM images and SAED patterns confirmed that fresh 55%Sm 5 Mn 95 /MSU-S existed in high ordered mesoporous structure and the nanosized Sm 2 O 3 and Mn 3 O 4 particles occurred in highly dispersive polycrystallites. The valence state of Mn species and the regeneration process of used sorbent were characterized by X-ray photoelectron spectroscopy (XPS) and TG/DSC. In addition, the effects of reaction temperature, feed composition and Sm/Mn atomic ratio in sorbents on desulfurization performance were investigated.
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