Improving the Coke Resistance of Ni‐Ceria Catalysts for Partial Oxidation of Methane to Syngas: Experimental and Computational Study

Abstract

The synthesis of syngas (H 2 : CO = 2) via catalytic partial oxidation of methane (CPOM) is studied over noble metal doped NiÀ CeO 2 bimetallic catalysts for CPOM reaction. The catalysts were synthesized via a controlled deposition approach and were characterized using XRD, BET-surface area analysis, H 2 -TPR, TEM, Raman and TGA analysis. The catalysts were experimentally and computationally studied for their activity, selectivity, and long-term stability. Although the pure 5Ni/CeO2 catalyst showed high initial activity (~90%) of CH 4 conversion, it rapidly deactivates around 20% of its initial activity within 140 hours of TOS. Doping of Ni/CeO 2 catalyst with noble metal was found to be coke resistant with the best-performing NiÀ Pt/CeO 2 catalyst showed ~95% methane conversion with > 90% selectivity at a temperature of 800 °C, having exceptional stability for about 300 hours of time-on-stream (TOS). DFT studies were performed to calculate the activation barrier for the CÀ H activation of methane over the Ni, Ni 3 Pt, Ni 3 Pd, and Ni 3 Ru (111) surfaces showed nearly equal activation energy over all the studied surfaces. DFT studies showed high coke formation tendency of the pure Ni (111) having a very small CÀ C coupling activation barrier (14.2 kJ/ mol). In contrast, the Ni 3 Pt, Ni 3 Pd, and Ni 3 Ru (111) surfaces show appreciably higher CÀ C coupling activation barrier (7 0 kJ/mol) and hence are more resistant against coke formation as observed in the experiments. The combined experimental and DFT study showed NiÀ Pt/CeO 2 as a promising CPOM catalyst for producing syngas with high conversion, selectivity and long-term stability suited for future industrial applications.

DFT Investigation of CH4 and H2O Adsorption on Pd (111), Ni (111), Pt (111), and Ir(111) Surfaces

“…CH4 is a primary constituent of natural gas and plays a remarkable role in hydrogen generation. The primary methods utilised in the production of hydrogen include methane steam reforming (SRM) [CH4 + H2O →+ 3H2+ CO] [2], partial oxidation of methane [CH4 + ½O2 → 2H2 + CO] [3], and methane dry reforming [CO2 + CH4 → CO + 2H2] [4]. The SRM is the process by which CH4 and H2O react over a nickel catalyst, accounting for nearly 98% world's supply of hydrogen gas [5].…”

Design and Verification of Key Components of a New Selective Catalytic Reduction System in a Petrochemical Captive Power Plant

“…The high-speed flow of flue gas will carry ammonia gas through the catalyst layer quickly, concentrating in the middle back area of the catalyst layer [20][21][22]. This results in issues such as insufficient reaction, catalyst layer blockage, and deactivation [23][24][25]. Therefore, uniform distributions of flow field velocity and NH 3 concentration are key to ensuring a high deNO x efficiency of an SCR system [26,27].…”