EXPERIMENTAL AND THERMODYNAMIC MODELING STUDIES FOR ENHANCED PHOTOCATALYTIC PARTIAL OXIDATION OF METHANE TO METHANOL

Abstract

This study investigates the potential of photocatalytic processes for the selective conversion of methane into valuable liquid fuels, particularly methanol, addressing the need for efficient, alternative, and clean energy carriers and fuels. This work researches the selectivity towards the reaction products ethanol and methanol. Two pristine photocatalysts, W18O49 and g-C3N4, along with two of their respective composites (W18O49 (0.3)/g-C3N4 and W18O49 (0.6)/g-C3N4), were synthesized and analyzed using SEM, XRD, BET, and UV-VIS spectroscopy techniques. The photocatalytic test is conducted to assess their performance. When W18O49 is coupled with g-C3N4, the yield of methanol increases. Among the four catalysts tested, W18O49(0.3)/g-C3N4 demonstrated the highest methanol yield (62.3 µmol g−1 h−1) under visible light, while and W18O49(0.6)/g-C3N4 exhibited the highest yield (56.9 µmol g−1 h−1) under UV light. These results show the potential of catalyst composites in enhancing the selectivity and efficiency of methane conversion. Furthermore, a comparative evaluation of two distinct fuels (methanol and hydrogen) production and power generation routes via fuel cells is evaluated. The first route includes the methanol production from direct partial oxidation of methane to methanol, where the methanol is condensed, stored, and sent to a direct methanol fuel cell. The second route is hydrogen production from solar methane cracking, where heat is supplied from concentrated solar power, and hydrogen is stored and directed to a hydrogen fuel cell. This study aims to provide insights into their production conditions, energy, and exergy efficiencies. A comprehensive thermodynamic analysis is performed. The methanol and hydrogen routes' overall energy and exergy efficiencies are 39.75%, 38.35%, 35.84%, and 34.58%, respectively. The highest exergy destruction rate of 1605 kW is observed for the partial oxidation of methane to methanol. The methanol and hydrogen routes generate 32.087 MWh and 11.582 MWh of electricity for 16-hour operation, respectively.

Date of Award	2024
Original language	American English
Awarding Institution	HBKU College of Science and Engineering