Study of MnO₂/Ni-MCM-41 Catalyst for CO Oxidation in Motorcycle Exhaust Emissions

Alvin Romadhoni Putra Hidayat (Department of Chemistry, Universitas Diponegoro)
Alvin Rahmad Widyanto (Department of Applied Chemistry, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan)
Ratna Ediati (Department of Chemistry, Institut Teknologi Sepuluh Nopember, Surabaya 60111, Indonesia)
Hafildatur Rosyidah (Department of Chemistry, Institut Teknologi Sepuluh Nopember, Surabaya 60111, Indonesia)
Romario Abdullah (College of Vocational Studies, Bogor Agricultural University (IPB University), Bogor, Indonesia)

Greensphere: Journal of Environmental Chemistry
Vol 6, No 1 (2026): Volume 6 Issue 1 tahun 2026

Incomplete combustion in vehicles produces hazardous gases such as carbon monoxide (CO), which is harmful to human health. This study aimed to synthesize MnO₂/Ni-MCM-41 as a catalyst for CO oxidation to CO₂. MCM-41 was synthesized via a hydrothermal method, followed by Ni doping to form Ni-MCM-41 and subsequent wet impregnation to obtain MnO₂/Ni-MCM-41. The materials were characterized by FTIR, XRD, TEM, and N₂ physisorption, while catalytic activity for CO oxidation was evaluated using a four-stroke motorcycle. FTIR spectra showed a band at 1633.76 cm⁻¹ attributed to –OH vibrations corresponding to Si–OH groups in MCM-41, whereas XRD patterns exhibited characteristic peaks at 2θ = 2.5° for MCM-41 and 2θ = 25° for δ-MnO₂. TEM analysis confirmed the hexagonal mesostructure of MCM-41, consistent with previous reports, while N₂ physisorption revealed a type IV isotherm, indicating a mesoporous structure. Ni incorporation decreased the specific surface area but enhanced the number of active sites. Increasing reaction time reduced CO concentration, while CO₂ concentration increased correspondingly. The optimum catalytic performance was obtained for MnO₂/Ni-MCM-41 with an impregnation time of 10 h.