Strong metal-support interaction induced sintering-resistant Ni nanoparticles supported on highly CO2-activating vanadium hydroxyapatite for dry reforming of methane

Abstract

Sintering of Ni-based catalysts and the following detrimental carbon depositions are still the major challenges to be overcame in the high-temperature dry reforming of methane (DRM) process. Herein, we for the first time induced classical strong metal-support interaction (SMSI) between Ni nanoparticles and vanadate substituted hydroxyapatite (VAP) under H2 atmosphere at as low as 300 ℃ (Ni/VAP-H300) to hinder the sintering of Ni nanoparticles during DRM process. TEM and element mapping analysis unambiguously exhibit the configuration of Ni nanoparticles encaged within the partially reduced VAP overlayer and subsequent linear-scan EDS investigations on the Ni/VAP-H300 at the reaction time of 25 h, 100 h and 260 h further elucidate the relatively intact VAP overlayer during the reaction, thus the CH4 conversion merely decreasing from 92 % to 79 % after stability test for 260 h. In contrast, Ni nanoparticles supported on conventional hydroxyapatite (Ni/HAP) give inferior stability, CH4 conversion drastically decreasing from 91 % to 42 % only after 25 h due to the absence of SMSI. Moreover, there also occurs electron-transfer between Ni nanoparticles and the adjacent VAP overlayer, thus showing higher CH4 decomposition activity compared with Ni/HAP. Combined with the excellent CO2-activating property of VAP support identified by CO2-TPD and gasification tests of the deposited carbon, the as-obtained Ni/VAP demonstrates outstanding initial activity and decent stability during DRM, which broadens the horizons of improving catalytic stability even under harsh reaction conditions by precisely exploiting the SMSI.