Highly efficient dehydrogenation of dodecahydro-N-ethylcarbazole over Al2O3 supported PdCo bimetallic nanocatalysts prepared by galvanic replacement

NEC is one of the most promising liquid organic hydrogen storage materials. The highly efficient and low cost dehydrogenation catalysts are crucial for large-scale hydrogen storage. In this paper, Co/Al2O3 precursors were prepared by chemical reduction, and then a series of Pd1Con/Al2O3 catalysts for 12H-NEC dehydrogenation was prepared by galvanic replacement of Pd2+ using Co as a template and reducing agent. The prepared catalysts were characterized by TEM, FT-IR, XPS, H2-TPR and H2-TPD. The results demonstrated that Pd1Con NPs were uniformly dispersed over the surface of Al2O3 in the form of Co@Pd core-shell structure, CoPd alloy and PdNPs, with an average particle size of 2.78 nm. The electron transfer occurred between Co and Pd. For the dehydrogenation of H12-NEC, the produced Pd1Co5/Al2O3 catalyst exhibited excellent catalytic activity. The dehydrogenation efficiency was 100% at 180 degrees C for 3 h and 98.5% at 150 degrees C for 6 h, and TOF reached 1.414 gH2/gPd min-1, which was significantly higher than that of monometallic Pd/Al2O3 catalysts and that reported in the literature. The kinetic studies of the catalytic 12H-NEC dehydrogenation showed that 4H-NEC -> NEC is the ratelimiting step with the highest apparent activation energy of 68.72 kJ/mol. The hydrogen release efficiency remained essentially unchanged after four cycles.