Ru–Pd dual active site catalyst exhibited more excellent performance in sequential hydrogenation of nitroaromatics to alicyclic amines.

Highly efficient synthesis of bio-based pentamethylene dicarbamate from pentanediamine and ethyl carbamate was successfully achieved over the well-defined TiO2 catalysts, which provides a green and sustainable way for the production of bio-based isocyanates or polyurethane.

Saturated hydrogenation of aromatic amines is a crucial methodology for synthesizing alicyclic amines. The dispersion of Ru atoms occurred after chemical reduction treatment, which was constrained to B and N coordination, further promoting the Ru species’ uniform distribution through interaction with the B–N bond of boron nitride. Moreover, the Ru coordinated with h-BN and further formed the stable catalytic active center. By virtue of its excellent stability, the hydrogenation of MDA executed in the fixed-bed reactor could run for more than 200 h. However, the density functional theory showed that the hydrogenation rate of the second benzene ring was comparatively slower because of the strong intermediate adsorption during the conversion from 4,4′-diaminodiphenylmethane to 4,4′-diaminodicyclohexylmethane. Furthermore, Ru/h-BN exhibited excellent performance in the hydrogenation of other aromatic amines, resulting in corresponding alicyclic amines. Therefore, this research offers a stable and effective catalyst for the green hydrogenation of aromatic amines leading to the production of alicyclic amines.

Carbonylation of m -xylylene diamine (XDA) with ethyl carbamate to produce m -xylylene dicarbamate (XDC), which is the crucial intermediate for the production of m -xylylene diisocyanate (XDI), over the hierarchical TS-1 (HTS-1) zeolite catalyst was studied. The catalysts were characterized by Brunauer–Emmett–Teller, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and temperature-programed desorption of ammonia techniques systematically. The results showed that the high performance of HTS-1 could be attributed to the weak acidity and high V meso / V total ratio of the catalyst. Impacts of reaction time and reusage on the HTS-1 catalyst were also investigated. Under 6 h and 200 °C, XDA conversion could reach 100% with 88.5% XDC yield. Furthermore, partial loss of Ti active sites with Lewis acidity on the catalyst surface led to the decrease of XDC yield during recycling. Moreover, a possible reaction mechanism for the title reaction was primarily proposed.