Comparative Study of Commercial Silica and Sol-Gel-Derived Porous Silica from Cornhusk for Low-Temperature Catalytic Methane Combustion.

The synthesis and characterization of sol-gel-derived cornhusk support for low-temperature catalytic methane combustion (LTCMC) were investigated in this study. The prepared cornhusk support was impregnated with palladium and cerium oxide (Pd/CeO ₂ ) via the classical incipient wetness method. The resulting catalyst was characterized using various techniques, including X-ray diffraction (XRD), N ₂ physisorption (BET), transmission electron microscopy (TEM), and hydrogen temperature-programmed reduction (H ₂ -TPR). The catalytic performance of the Pd/CeO ₂ /CHSiO ₂ catalyst was evaluated for methane combustion in the temperature range of 150-600 °C using a temperature-controlled catalytic flow reactor, and its performance was compared with a commercial catalyst. The results showed that the Pd/CeO ₂ dispersed on SiO ₂ from the cornhusk ash support (Pd/CeO ₂ /CHSiO ₂ ) catalyst exhibited excellent catalytic activity for methane combustion, with a conversion of 50% at 394 °C compared with 593 °C for the commercial silica catalyst (Pd/CeO ₂ /commercial). Moreover, the Pd/CeO ₂ /CHSiO ₂ catalyst displayed better catalytic stability after 10 h on stream, with a 7% marginal loss in catalytic activity compared with 11% recorded for the Pd/CeO ₂ /commercial catalyst. The N ₂ physisorption and H ₂ -TPR results indicated that the cornhusk SiO ₂ support possessed a higher surface area and strong reducibility than the synthesized commercial catalyst, contributing to the enhanced catalytic activity of the Pd/CeO ₂ /SiO ₂ catalyst. Overall, the SiO ₂ generated from cornhusk ash exhibited promising potential as a low-cost and environmentally friendly support for LTCMC catalysts.