Encapsulated Pt-GDC catalyst-coated monolith for hydrogen generation and NOx reduction in an integrated REGR system

Most diesel vehicles still rely on internal combustion engines due to their high torque and power demands. However, diesel combustion inevitably generates nitrogen oxides (NOx) which poses significant environmental challenges. To address this issue, reformed exhaust gas recirculation (REGR) system integrating diesel reforming and NOx reduction was developed using Pt supported gadolinium-doped ceria (Pt-GDC) catalyst synthesized via polyol method. The catalyst exhibited strong metal-support interaction (SMSI) and high oxygen vacancy concentrations enabling stable diesel reforming and efficient NOx reduction. Structural tuning through calcination temperatures revealed that partial encapsulation of Pt nanoparticles at 600 °C provided optimal hydrogen production and coke resistance. The Pt-GDC catalyst coated on honeycomb monolith with optimized slurry viscosity demonstrated sustained hydrogen production of 11.2 % for 60 h under exhaust gas conditions and directly reduced the NOx emission up to 98.0 % at EGR rate of 37.4 %. Further studies should aim to develop catalysts effective at lower exhaust temperatrues below 500 °C. Evaluating the impact of hydrogen addition on engine performance and integrating the system with selective catalytic reduction (SCR) could further enhance NOx reduction.