Enhanced CO2 utilization in dry reforming of methane achieved through nickel-mediated hydrogen spillover in zeolite crystals

Abstract

Transformation of CO2 into precursors for chemicals and fuels by self-contained reducing gas contaminants (for example, CH4) is attractive from a carbon economy perspective. Reducing as much CO2 as possible using a limited amount of reducing gas would be ideal, but general dry reforming (DRM) schemes consume stoichiometric amounts of methane for CO2 reduction. Here we develop a process with high reducibility of methane relative to conventional DRM, using up to 2.9 mol of CO2 per mol of CH4. Key to this success are Ni nanoparticles, fixed within the matrix of an aluminosilicate zeolite catalyst (Ni@HZSM-5), that enhance hydrogen spillover to favour the reduction of CO2. This process achieves an energy cost for reducing CO2 of 113.6 kJ per mol CO2, which is 31.9% lower than the conventional DRM process with stoichiometric transformation of CO2 and methane. In addition, the rigid zeolite framework could minimize coke formation and prevent Ni sintering. Carbon dioxide reforming can be used to valorize hydrocarbon-containing CO2 streams without the use of external reductants, but existing methods remain inefficient. Here, an HZSM-5-encapsulated nickel catalyst is introduced that features a remarkable methane dry reforming activity combined with high methane utilization.