Supported PdZn nanoparticles for selective CO2 conversion, through the grafting of a heterobimetallic complex on CeZrOx

Controlling the stoichiometry of supported bimetallic nanoparticles is essential in many catalytic reactions, notably selective CO2 hydrogenation. Thus, a new strategy to ensure the preferred stoichiometry (1:1) of supported bimetallic PdZn nanoparticles is presented, involving the deposition of a heterobimetallic precursor, [PdZn(mu-OOCMe)4]2 on a CeZrOx support. After calcination and reduction, the material contained mainly a PdZn alloy, as revealed by powder XRD and XAFS, and further supported by XPS, TEM-EDX, elemental analysis and insitu IR at low temperature using CO as probe molecule. Moreover, a minor phase of oxidized Zn was determined by XAFS. This PdZn/CeZrOx reduced catalyst was combined with SAPO-34 to form a tandem catalytic system for CO2 conversion to hydrocarbons. This system could readily convert CO2 and H2 at high temperature (380 degrees C) into hydrocarbons with a conversion of 24% and high relative selectivity in light hydrocarbons (C2-C3: 82%) with virtually no deactivation of the catalyst after 16 h on stream. Controlled experiments were performed with Pd/ CeZrOx and Zn/CeZrOx in order to gain supplementary insights on this system: Pd/CeZrOx gave only methane and Zn/CeZrOx gave mainly CO under the same conditions. The latter clearly shows that the control of the formation of PdZn phase has great impact for the selective production of hydrocarbons.

Automated summary

This study presents a new strategy to control the stoichiometry of supported bimetallic PdZn nanoparticles and achieve high selectivity in hydrocarbon production from CO2 and H2. The control of PdZn phase formation is shown to have a significant impact on the selectivity of the products.