Structure sensitivity reaction of chloroform hydrodechlorination to light olefins using Pd catalysts supported on carbon nanotubes and carbon nanofibers

The upgrading of wasted chloroform in hydrodechlorination for the production of olefins such as ethylene and propylene is studied by employing four catalysts (PdCl/CNT, PdCl/CNF, PdN/CNT, and PdN/CNF) prepared by different precursors (PdCl2 and Pd(NO3)2) supported on carbon nanotubes (CNT) or carbon nanofibers (CNF). TEM and EXAFS-XANES results confirm that Pd nanoparticle size increases in the order: PdCl/CNT < PdCl/CNF ∼ PdN/CNT < PdN/CNF, descending the electron density of Pd nanoparticles in the same order. It illustrates that PdCl-based catalysts show donation of electrons from support to Pd nanoparticles, which is not observed in PdN-based catalysts. Moreover, this effect is more evident in CNT. The smallest and well-dispersed Pd nanoparticles (NPs) on PdCl/CNT with high electron density favor an excellent and stable activity and a remarkable selectivity to olefins. In contrast, the other three catalysts show lower selectivity to olefins and lower activities which suffer strong deactivation due to the formation of Pd carbides on their larger Pd nanoparticles with lower electron density, compared to PdCl/CNT

The authors acknowledges FEDER/Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación (CTM2017-85498-R) and Comunidad de Madrid/UAM (SI1/PJI/2019-00487) for financial support. The authors acknowledge to ALBA Synchrotron facility for beamtime at CLAESS (experiment 2016021666-2). Maria Martin Martinez acknowledges a postdoctoral grant (2017-T2/AMB-5668), from the Comunidad de Madrid “Atracción de Talento” programme. Sichen Liu acknowledges Ministerio de Ciencia e Innovación for his research grant (PRE2018-084424)