Designing a Ce/In-CHA OXZEO catalyst for high-efficient selective catalytic reduction of nitrogen oxide with methane

Selective catalytic reduction of nitrogen oxides with methane (CH 4 -SCR) has emerged as a promising technology for mitigating exhaust emissions from natural gas vehicles, while its insufficient catalytic activity and durability are key barriers to application. In this study, novel Ce/In-CHA OXZEO catalysts were prepared, demonstrating exceptional catalytic performance and stability in the CH 4 -SCR reaction. Over these OXZEO catalysts, indium species predominantly existed in the form of InO + and In x O y within the CHA zeolite framework, while CeO 2 nanoparticles primarily resided as an external layer. During the CH 4 -SCR reaction, NO oxidation to form NO 2 and nitrate species was triggered by CeO 2 , which further enhanced the activation of CH 4 on InO + sites, thus boosting the low-temperature CH 4 -SCR process by facilitating the formation of the key intermediate CH 3 NO 2 . The synergy between InO + and CeO 2 underscores the exceptional performance and stability of the Ce/In-CHA with a low SiO 2 /Al 2 O 3 ratio in reducing NO x and CH 4 emissions.