Glycerol Steam Reforming for Hydrogen over Mo-Modified Attapulgite-Based Zeolite-Supported Ni-Based Catalysts

Obtaining green hydrogen from glycerol steam reforming (GSR) is a promising approach for the efficient utilization of crude glycerol derived from the biodiesel market, while it faces significant challenges. Herein, Mo-modified attapulgite-based zeolite (AZc)-supported Ni-based catalysts (named as NixMo/AZc) were prepared for GSR. It demonstrated that AZc could reduce the proportion of strong acid sites and promote the reduction of nickel species; meanwhile, the Mo additive yielded an intermetallic interaction between nickel and molybdenum to facilitate the formation of Ni–Mo alloy phases and abundant oxygen vacancies (OV). These characteristics effectively inhibited the dehydration of glycerol, the sintering of active Ni metals, and the formation of carbon deposits during GSR process. Among them, Ni3Mo/AZc achieved the highest glycerol conversion (95.3%) and hydrogen yield (77.3%) and maintained the superior catalytic stability during 50 h of GSR at 600 °C. Additionally, the reaction pathway investigation exhibited that Ni3Mo/AZc promoted the dehydrogenation of glycerol and the acetol intermediate and the breakage of C–C bonds; then, its metallic Ni and Ni–Mo alloy sites coupled with OV enhanced the water–gas shift reaction and the steam reforming of various intermediates to yield more hydrogen. This study provides a feasible strategy for the high-value utilization of glycerol through steam reforming along with the efficient production of green hydrogen.