Highly dispersed palladium nanoparticles (NPs) supported on UiO-66 as catalyst for CO 2 methanation were prepared by supercritical fluid deposition (SFD). As a result, the most suitable Pd precursor salt and co-solvent are Na 2 PdCl 4 and ethanol/DMF, respectively. The best SFD process condition to deposit the Pd precursor on UiO-66 is 40 °C, 10 MPa and 2 h. Under the above condition, 4% Pd/UiO-66 exhibits the highest activity with 53% of CO 2 conversion and 95% of CH 4 selectivity while the turnover frequency (TOF) value is 3669.4 h −1 . The catalysts were characterized by XRD, BET, TEM, XPS, TGA, CO-DRIFTS and ICP-OES to investigate the structure–activity relationship. The 4% Pd/UiO-66 with the average size of 2.2 nm of Pd prepared in assistance of supercritical fluid behaved the similar activity as the 6%Pd/UiO-66 with average size of 9.7 nm of Pd prepared by sol–gel method. It is showed prospect of technique for reducing noble metal loading resulting from high dispersion effect.
Jirong Long,Yuxuan Mao,Yiwei Long,Guozhang Chang,Lungang Chen,Wenguang Zhou,Jinxing Long,Yong Liu
Hydrodeoxygenation of lignin-derived phenols into high-value cycloalkanes under mild conditions is challenging. Herein, we report a Ru NPs @HZSM-5 catalyst with a unique metal-support interactions that achieves 100 % guaiacol conversion and 99.7 % cyclohexane selectivity at 160 °C and 1 MPa H 2 . Comparative studies with single-atom and aggregated Ru catalysts reveal that well-dispersed Ru nanoparticles coupled with acid sites offer superior activity and selectivity. Kinetic analysis and in situ DRIFTS demonstrate a sequential mechanism involving rapid hydrogenation of the aromatic ring followed by rate-limiting deoxygenation steps. Characterizations and CO-DRIFTS confirm particle sizes, optimal metal-support interactions, and enhanced acidity in Ru NPs @HZSM-5. Theoretical calculations further reveal favorable electronic states and lower energy barriers for deoxygenation on Ru NPs @HZSM-5. The catalyst also shows broad substrate compatibility, efficiently converting various lignin-derived phenolics. This work provides valuable insights into the critical synergy between metal nanoparticles and acidic supports for efficient lignin upgrading.
危险品化学品经营许可证（带存储）