Carbon dioxide reforming of methane over Ni-based catalysts: a comprehensive review of coke suppression strategies.

Catalytic dry reforming of methane (DRM) can provide aids for turning two important greenhouse gases methane and carbon dioxide (CH4 and CO2) into valuable synthesis gas. For Ni-based catalysts - the most promising because of low costs and high activity industrial applications are severely limited by fast deactivation due to carbon deposition (coking). A focused and critical assessment of coke suppression strategies for Ni based DRM catalysts is provided in this review. Our systematic review includes: (1) basic (MgO) and redox-active (CeO2 ZrO2) support roles in CO2 activation and carbon gasification; (2) noble (Pt, Ru) and non-noble (Fe, Co, Mo) promoters altering the surface chemistry of Ni; (3) bi- and trimetallic formulations providing synergistic anti-coking interfaces; (4) thermodynamics and kinetics of coke formation; (5) catalyst deactivation mechanisms; regeneration methods; (6) the effect of synthesis techniques (impregnation,-and co precipitation sol-gel) on Ni dispersion on coke resistance. We critically interrogate and compare key contradictory findings within the literature-including its dominant source of coke (methane cracking vs. Boudouard reaction), and most beneficial promoter (Pt vs. Ru). Data from the literature suggest a range of reported coke deposition rates (15 mg C g_cat-1 h-1) as well as catalyst stability durations (20-200 h under 1 bar conditions), each in significant deficit of industrial targets (>8000 h on stream, 10 bar), resistance to trace impurities (H2S), and pilot scale tests, outlining a route to durable, coke resistant Ni-based catalysts for sustainable DRM.