Ultra-Low Pt Loading Bimetallic PtNi Catalyst on Nano-LTL Zeolite for the Selective Hydrogenation of Halonitrobenzenes.

The selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) is of great importance for the production of dyes, pesticides, and pharmaceuticals, but it is often plagued by the undesired hydrodechlorination side reaction. In this work, we report a PtNi bimetallic catalyst supported on nano-sized LTL zeolite (PtNi/Nano-HL) for the selective hydrogenation of p-chloronitrobenzene under mild conditions. The catalyst was systematically characterized by X-ray diffraction (XRD), nitrogen sorption (N2 sorption), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and ammonia temperature-programmed desorption (NH3-TPD). The results reveal abundant oxygen vacancies (RIR = 0.73) and an optimized distribution of medium-strong acid sites on the catalyst surface, as well as electronic interaction between Pt and Ni, which collectively enhance the catalytic performance. Remarkably, the PtNi/Nano-HL catalyst achieves 100% conversion and over 99% selectivity for p-chloroaniline under ambient conditions (30 °C, 0.1 MPa H2) using ethanol as a solvent. Even after 24 recycling runs, it retains 100% conversion and >93% selectivity, demonstrating excellent stability. Moreover, the catalyst requires an extremely low Pt loading (only 0.11 wt%) and exhibits good substrate universality for various substituted nitroarenes. This work provides a promising strategy for designing high-performance bimetallic catalysts on nano-zeolite supports for the selective hydrogenation of halonitrobenzenes.