Engineering PdCu and PdNi bimetallic catalysts with adjustable alloying degree for the dehydrogenation reaction of dodecahydro-N-ethylcarbazole

The NECZ/12H-NECZ (N-ethylcarbazole/dodecahydro-N-ethylcarbazole) system is regarded as the most potential liquid organic hydrogen carrier. However, the low activity, selectivity of NECZ and high cost of catalysts for the dehydrogenation reaction restrict its efficiency and commercial applications. In this work, a series of bimetallic Pd-M(M = Cu, Ni)/SiO2 catalysts were prepared and employed to enhance catalytic activity and selectivity of NECZ for the 12H-NECZ dehydrogenation reaction. Pd3Ni1/SiO2 exhibited high catalytic performance with 100% conversion, 91.1% selectivity of NECZ and 5.63 wt% hydrogen release amount at 453 K, 101.325 kPa for 8 h. The TOF (turnover frequency) of Pd3Ni1/SiO2 is enhanced by 42.4% compared with Pd/SiO2. Combined with the characterization analysis, it was found that adjusting the alloying degree or the alloy phase in the PdCu and PdNi bimetallic catalysts could significantly enhance the dehydrogenation activity and selectivity, which were dependent on the component of bimetallic catalysts. This work may provide theoretical guidance for designing the efficient and low-cost bimetallic catalysts for the dehydrogenation of 12H-NECZ, which could boost the commercial applications of liquid organic hydrogen carriers.