Thermal-stable Pd@mesoporous silica core-shell nanocatalysts for dry reforming of methane with good coke-resistant performance

Dry reforming of methane (DRM) reaction is an environment-friendly process to convert greenhouse gases, methane (CH 4 ) and carbon dioxide (CO 2 ) into synthesis gases for industrial application. However, the catalysts used for DRM reaction always deactivate at high temperatures due to the sintering of metal nanoparticles and coking on the active surface. Core-shell structures composed of metal cores surrounded by oxide shells (core-shell structures) have been confirmed to be thermal-stable by solving the two problems. Pd@SiO 2 core-shell nanocatalyst has been prepared by using a sol-gel process, along with two supported catalysts prepared by using impregnation method in this work. The catalysts were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), N 2 adsorption-desorption isotherms, CO chemisorption, inductively coupled plasma optical emission spectrometry (ICP-OES). The Pd@SiO 2 after thermal treatment at 700 °C for 6 h exhibits no obvious sintering. For DRM reaction catalyzed by Pd@SiO 2 core-shell nanocatalyst, the conversions of CO 2 and CH 4 are 89% and 83% respectively, which show no significant decrease for >10 h. However, two supported Pd catalysts (Pd cub/SiO 2 and Pd/SiO 2 ) deactivate to a very low activity (conversion lower than 20%). The results suggest that the Pd@SiO 2 nanocatalyst is excellent for DRM reaction, which also can be used for other heterogeneous catalysis reaction at high temperatures.