Abstract:

As an important type of metal–organic framework (MOF), Zr-MOF shows excellent CO₂ adsorption performance. In this work, a Zr-MOF was synthesized by a solvothermal method and adopted to support Ru through simple incipient-wetness impregnation. Then the Ru/Zr-MOF was applied for CO₂ hydrogenation  (V_H2 : V_CO2= 4:1)  with the assistance of dielectric barrier discharge (DBD) plasma. The hydrogenation of CO₂ results showed that methane was produced selectively under the synergistic effect between plasma and the Ru/Zr-MOF catalyst, and the selectivity and yield of methane reached 94.6% and 39.1%, respectively. The XRD and SEM analyses indicate that the basic crystalline phase structure and morphology of the Zr-MOF and Ru/Zr-MOF remained the same after DBD plasma treatment, suggesting that the catalysts are stable in plasma. The guest molecules in the pores of the Zr-MOF are removed and the Ru³⁺ ions are reduced to metallic Ru⁰ in the reduction atmosphere according to the BET and XPS results, which are responsible for the high performance of plasma with the Ru/Zr-MOF catalyst. In situ optical emission spectra of pure plasma, plasma with Zr-MOF, and plasma with Ru/Zr-MOF were measured, and the active species of C, H and CH for CO₂ hydrogenation were detected. The plasma-assisted Ru/Zr-MOF exhibited high catalytic activity and stability in CO₂ hydrogenation to methane, and it has great guiding significance for CO₂ hydrogenation by using plasma and MOF materials.

Key words: dielectric barrier discharge,  cold plasma,  Zr-MOF,  carbon dioxide hydrogenation, methane 

Received: 10 October 2018    

Fund:

This work is supported by National Natural Science Foundation of China (Nos. 21673026, 21773020, 11505019), the Liaoning Innovative Talents in University (No. LR2017025), and the Liaoning Natural Science Foundation (No. 20180550085).