Tuning the alloy degree for Pd-M/Al2O3 (M=Co/Ni/Cu) bimetallic catalysts to enhance the activity and selectivity of dodecahydro-N-ethylcarbazole dehydrogenation

Hydrogen is a promising candidate to substitute the fossil fuels. However, the efficient hydrogen storage technologies restrict the commercial applications. Developing new cat-alysts with high activity and selectivity is important for the dehydrogenation reaction in N-ethylcarbazole/dodecahydro-N-ethylcarbazole (NECZ/12H-NECZ) hydrogen storage sys-tem. In this work, a series of Pd-M/Al2O3 (M = Co, Ni and Cu) bimetallic catalysts are synthesized successfully and show good performance in the dehydrogenation reaction of 12H-NECZ than the commercial Pd/Al2O3 catalyst. The Pd1Co1/Al2O3 catalyst (Practical Pd content = 2.4136 wt%) showed the highest catalytic performance with 95.34% H-2 release amount, TOF of 230.5 min(-1) and 85.4% selectivity of NECZ. Combined with the charac-terization analysis, it can be proposed that the dehydrogenation performance of 12H-NECZ dependent on the alloy phases, reasonable electronic structures and nanoparticle size of catalysts. The fine-tuned alloy degree and appropriate nanoparticle size of Pd1Co1/Al2O3 bring the 17.7% increase of H-2 release amount and 99.5% increase of NECZ selectivity than those of Pd/Al2O3. For the bimetallic catalysts, the enhancement of selectivity of NECZ is mainly from the increase of the kinetic constant of rate-limiting step. (c) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

Automated summary

A series of Pd-M/Al2O3 bimetallic catalysts were successfully synthesized in this study, showing higher hydrogen release amount and NECZ selectivity by fine-tuning the alloy degree and nanoparticle size. The increase in NECZ selectivity mainly comes from the enhancement of the kinetic constant of the rate-limiting step.