Metal redispersion strategy for regeneration of sepiolite derived Co-phyllosilicate catalyst during glycerol steam reforming

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Metal sintering and coke deposition have become main and irreversible obstacles for catalyst deactivation during H2 production from glycerol steam reforming (GSR). The regenerability of 15Co/SEP catalyst with a phyllosilicate derived strong metal-support interaction (SMSI) was probed by five successive GSR/regeneration cycles in order to evaluate the deactivation process and initial reactivity recovery. Two different regeneration methods were selected for the cycles: redox regeneration and combined regeneration. After the combined regeneration, reproducible GSR behaviors were obtained among the whole cycles. An almost recovery of initial activity (∼94 % of conversion and ∼ 73 % of H2 yield) and 50 h stability was noticed at 15Co/SEP-5 catalyst. By various characterizations analysis of fresh and spent catalysts, it was observed that irreversible metal sintering was aggravated by the redox regeneration, thus provoked initial activity loss and accelerated coking deactivation tendency. The combined regeneration achieved phyllosilicate recrystallization and metal exsolution/redispersion by a combination of NH4F-HNO3 assisted recrystallization and redox treatments, which ensured a small increase in Co0 nanoparticle size (13.2 nm vs. 15.3 nm) and coke deposition (23.9 wt% vs. 27.3 wt%) and inconspicuous change in the C1 species selectivity. The results suggested that 15Co/SEP catalyst is a promising candidate for commercialized GSR due to the favorable regenerability.