Investigation of palladium catalysts in mesoporous silica support for CO oxidation and CO2 adsorption

Rola Mohammad Al Soubaihi; Khaled Mohammad Saoud; Ahmed Awadallah-F; Ahmed Mohamed Elkhatat; Shaheen A Al-Muhtaseb; Joydeep Dutta

doi:10.1016/j.heliyon.2023.e18354

Investigation of palladium catalysts in mesoporous silica support for CO oxidation and CO₂ adsorption

Heliyon. 2023 Jul 17;9(7):e18354. doi: 10.1016/j.heliyon.2023.e18354. eCollection 2023 Jul.

Authors

Rola Mohammad Al Soubaihi¹, Khaled Mohammad Saoud², Ahmed Awadallah-F³, Ahmed Mohamed Elkhatat³, Shaheen A Al-Muhtaseb³, Joydeep Dutta¹

Affiliations

¹ Functional NanoMaterials Group, Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Hannes Alfvéns väg 12, 11419, Stockholm, Sweden.
² Virginia Commonwealth University in Qatar, Liberal Arts and Sciences Program, P.O. Box 8095, Doha, Qatar.
³ Department of Chemical Engineering, Qatar University, P.O. Box 2713, Doha, Qatar.

Abstract

The oxidation of Carbon monoxide (CO) to Carbon dioxide (CO₂) is one of the most extensively investigated reactions in the field of heterogeneous catalysis, and it occurs via molecular rearrangements induced by catalytic metal atoms with oxygen intermediates. CO oxidation and CO₂ capture are instrumental processes in the reduction of green-house gas emissions, both of which are used in low-temperature CO oxidation in the catalytic converters of vehicles. CO oxidation and CO₂ adsorption at different temperatures are evaluated for palladium-supported silica aerogel (Pd/SiO₂). The synthesized catalyst was active and stable for low-temperature CO oxidation. The catalytic activity was enhanced after the first cycle due to the reconditioning of the catalyst's pores. It was found that the presence of oxide forms of palladium in the SiO₂ microstructure, influences the performance of the catalysts due to oxygen vacancies that increases the frequency of active sites. CO₂ gas adsorption onto Pd/SiO₂ was investigated at a wide-ranging temperature from 16 to 120 °C and pressures ∼1 MPa as determined from the isotherms that were evaluated, where CO₂ showed the highest equilibrium adsorption capacity at 16 °C. The Langmuir model was employed to study the equilibrium adsorption behavior. Finally, the effect of moisture on CO oxidation and CO₂ adsorption was considered to account for usage in real-world applications. Overall, mesoporous Pd/SiO₂ aerogel shows potential as a material capable of removing CO from the environment and capturing CO₂ at low temperatures.

Keywords: Adsorption-desorption; CO oxidation; CO2 adsorption; Mesoporous SiO2 aerogel; Palladium; Supported catalyst.