Utilization of palm oil fuel ash (POFA) as catalyst support for methane decomposition

Abstract

An agricultural waste, palm oil fuel ash (POFA) has been evaluated as a Ni catalyst support for the methane decomposition process. The effects of solvent and pre-treatment technique during the POFA pre-treatment have been investigated towards the catalytic performance of Ni supported on POFA (Ni-POFA) catalyst prepared at 10 wt% Ni loading. Methane decomposition of Ni-POFA catalyst was carried out at 550 °C for 6 hrs. The POFA and Ni-POFA were characterized using X-ray fluorescence (XRF), X-ray diffractometer (XRD), N2 adsorption–desorption isotherms and field emission scanning electron spectroscopy (FESEM). The results showed that citric acid solution was the best solvent for POFA pre-treatment. The SiO2 content in the POFA pre-treatment improved from 42.4 to 72 wt%. Good CH4 conversion achieved by Ni-POFA catalyst in the methane decomposition was attributed to high SiO2 in the POFA treated with citric acid. Compared to conventional stirring, pre-treatment of POFA with ultra-sonication technique has produced POFA support with smaller particles size, and Ni-POFA catalyst with better BET surface area and better Ni dispersion. These catalyst properties have contributed to an exceptional catalytic performance of 71% of initial CH4 conversion and 4.2% of initial H2 yield of Ni-POFA catalyst in the methane decomposition. The work suggests that POFA has the potential to be utilized as catalyst support, and pre-treatment is crucial for a reasonable catalytic performance in methane decomposition.