Dry Reforming of Methane over Pyrochlore-Type La 2 Ce 2 O 7 -Supported Ni Catalyst: Effect of Particle Size of Support.

The properties of supports (such as oxygen vacancies, oxygen species properties, etc.) significantly impact the anti-carbon ability due to their promotional effect on the activation of CO 2 in dry reforming of methane (DRM). Herein, pyrochlore-type La 2 Ce 2 O 7 compounds prepared using co-precipitation (CP), glycine nitrate combustion (GNC) and sol-gel (S-G) methods, which have highly thermal stability and unique oxygen mobility, are applied as supports to prepare Ni-based catalysts for DRM. The effect of the calcining temperature (500, 600 and 700 °C) on La 2 Ce 2 O 7 (CP) has also been investigated. Based on multi-technique characterizations, it is found that the synthesis method and calcination temperature can influence the particle size of the La 2 Ce 2 O 7 support. Changes in particle size strongly modulate the pore volume, specific surface area and numbers of surface oxygen vacancies of the La 2 Ce 2 O 7 support. As a result, the distribution of supported Ni components is affected due to the different metal-support interaction, thereby altering the activity of the catalysts for cracking CH 4 . Moreover, the supports' abilities to adsorb and activate CO 2 are also adjusted accordingly, accelerating the removal of the carbon deposited on the catalysts. Finally, La 2 Ce 2 O 7 (CP 600) with an appropriate particle size exhibits the best catalytic activity and stability in DRM.