Transient Mechanistic Studies of Methane Steam Reforming over Ceria‐Promoted Rh/Al₂O₃ Catalysts

Abstract

Transient‐pulse experiments in temporal‐analysis‐of‐product (TAP) and conventional mode were performed to determine elementary reaction steps involved in the methane steam reforming reaction over Rh/Al2O3 and Rh/12 CeO2–Al2O3. TAP pulse experiments demonstrated that both catalysts dissociate methane at 773 K leading to hydrogen, carbon, and CHx adspecies. Conventional transient pulse experiments with alternating methane/argon and water pulses with a delay between them of 86, 73, and 5 s, respectively, showed that the reactivity of adspecies over the promoted and nonpromoted catalysts decrease with time. Ceria catalyzes the oxidation of carbon species by water.

CO2 conversion to syngas through the steam-biogas reforming process

“…Previously reported experimental data using Pd and Rh based catalysts show that bimetallic combination of catalysts perform better than monometallic catalysts by enhancing syngas selectivity, suppressing coke buildup, and mitigating active metal oxidation [6,[24][25][26]. Also CeZrO 2 -modification of Al 2 O 3 as catalytic support material leads to improved catalyst activity, thermal stability and metal dispersion, and reduces coke formation resulting from methane reforming [6,[27][28][29].…”

Recent Progresses in Understanding of Co-Based Fischer–Tropsch Catalysis by Means of Transient Kinetic Studies and Theoretical Analysis

“…The TAP technique has been applied to different reaction systems involving heterogeneous catalysis: Reaction transport (adsorption and diffusion) [44,45]; reforming of hydrocarbons [46][47][48][49][50][51]; hydrogenation and dehydrogenation reactions [52,53]; environmental catalysis [54][55][56][57][58]; oxidation reactions etc. [59][60][61][62][63][64][65][66][67].…”

Elucidating the Promotional Effect of Cerium in the Dry Reforming of Methane

“…Most of the benefits of cerium promotion in heterogeneous catalysis are attributed to the Ce 3+ /Ce 4+ interconversion capacity which allows an enhanced oxygen mobility [2–6] . Moreover, the physical and chemical properties of the active metal phase could be modified in the presence of ceria, affecting the performance in hydrogen production reactions [7–11] . Hence, cerium oxide has been widely explored in the reforming of hydrocarbons, as a promoter of highly active noble metals (Pt, Rh) [7,12–15] or cheaper non‐noble alternatives (Ni, Co) [16–21] .…”