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Pt/Co0.5Fe0.5Al2O4 catalysts with the average Pt particle size of 1.6–3.4 nm were prepared and applied to the selective hydrogenation of cinnamaldehyde (CAL). Not only the TOF was promoted from 0.19 to 2.70 s−1, but also the selectivity to cinnamyl alcohol (COL) was improved from 68% to 94%, with the increase of Pt particle size. Stronger interaction occurred between Co0.5Fe0.5Al2O4 and smaller-sized Pt particles, resulting in electron-deficient Pt particles, so that CO and CC bond could be activated simultaneously. However, electron-rich Pt species existed on Pt/Co0.5Fe0.5Al2O4 with larger Pt size, which is beneficial for the preferential activation of CO bond.

Summary: An ultrastable and efficient Cu@C/SiO2 nanocatalyst was fabricated for the hydrogenation of ethylene carbonate, in which Cu nanoparticles are encapsulated by sorbitol-derived graphitized carbon overlayers. During the calcination of Cu-sorbitol/SiO2 precursors under N2 atmosphere, sorbitol decomposed to CO and CO2. The in situ generated CO not only reduced Cu2+ to Cu0/Cu+, but also formed graphitized carbon overlayers on the Cu surface via the disproportionation of CO. The Cu@C/SiO2 catalyst exhibited superior catalytic performance (91% MeOH yield and 43.6 h−1 TOF) at a H2/EC molar ratio of 20. Of particular note, the Cu@C/SiO2 catalyst showed remarkable long-term stability during 736 h time-on-stream test without any deactivation. The graphitized carbon overlayers on the surface of Cu nanoparticles not only functioned synergistically with the surface Cu0/Cu+ sites to promote the EC hydrogenation but also suppressed the sintering of Cu nanoparticles. Furthermore, the interaction of Cu nanoparticles and graphitized carbon overlayers stabilized the surface Cu+/(Cu0+Cu+) ratio.

The hydrogenation of acetic acid-derived cyclohexyl acetate (CHA) is becoming a safe, efficient and promising route for the production of cyclohexanol (CHOL), an important chemical to produce e-caprolactam. In this work, Cu-Zr catalysts were prepared via different methods for the hydrogenation of CHA. The results showed that a Cu3Zr7-SG catalyst prepared by the sol-gel (SG) method was superior to Cu3Zr7-CP and Cu3Zr7-IM catalysts prepared by the coprecipitation (CP) and impregnation (IM) method, respectively. The Cu3Zr7-SG catalyst showed 97.4% CHA conversion and 95.5% selectivity to CHOL along with 96.3% selectivity to ethanol at 250 1C under 3 MPa of H2. Moreover, the Cu3Zr7-SG catalyst showed a mass specific activity of up to 29.8 gCHA gCu-1 h-1, higher than other Cu-based catalysts under similar conditions. Based on detailed characterization studies, it was found that the larger weak acid sites, more weak and moderate basic sites, higher Cu+/(Cu0 + Cu+) and oxygen vacancies on the surface of the Cu3Zr7-SG catalyst were beneficial for the hydrogenation of CHA. [ABSTRACT FROM AUTHOR]