Hydrogenation Of Biomass-derived Compounds Catalyzed By Pt, Pd Nanocrystals

Biomass resources are one kind of renewable resources. Various fine chemicals could be produced by reaction of biomass,which could solve the non-renewable and scarcity problem of crude oil and develop sustainable chemicals and energy. Therefore, it is significant to study the process and mechanism about the conversion of biomass. In this paper, various type of palladium or platinum monometallic and bimetallic nanocrystals catalysts were prepared by hydrothermal and oleophylic processes. The catalytic properties haves been evaluated in hydrogenation of furfural and citral to produce some useful chemicals such as furfuryl alcohol（FOL）, tetrahydrofurfuryl alcohol（THFA）, 1,2-pentanediol and citronellal.PdCu bimetallic nanocrystals catalysts with different ratio of metals and particle size were prepared by using octadecylamine as reductant through controlled reaction conditions. The catalysts were used to promote the hydrogenation of furfural under room temperature and normal pressure. By adjusting the ratio of Pd to Cu, FOL and THFA could be produced selectively in 98% and 93%, repectivelly. Based on the dynimcal analysis, the hydrogenation of furfural produces FOL preferential, whereas the selectivity to THFA is lower than 5%. FOL was hydrogenated further to form THFA.Pd nano particles with sheet and cube morphologys were synthesized. The effect of ligands and the nano Pd particles morphology on hydrogenation activity was also studied. Pd nanosheet had a higher reactive activity than Pd nanocube in hydrogenation of furfural. ODA ligand lowered the activity of Pd nanocube.PdCu Catalysts supported on the different carriers were prepared and the catalytic properties in hydrogenation of furfural were evaluated. The results showed that the carrier strongly affected the performance of supported catalyst. Among the supported catalysts, Pd1Cu2/CoO was the best catalyst for hydrogenation of furfural to FOL. The conversion of furfural could reach 99% and selectivity of FOL could reach 98% under 110°C, 3 MPa H2 and 3 h.Pt/MgAl-LDH catalysts were prepared by “one-pot” method and the catalytic properties in hydrogenation of FOL were evaluated. The results showed that the conversion of FOL was 97% and the selectivity of 1,2-pentanediol was 75% when the Pt/MgAl-LDH with molar ratio of Mg:Al being 5:1 under the reaction at 160°C, 3 MPa H2 for 4 h.PdAg bimetallic nanocrystals and PdAg-SnO₂ catalysts with different ratio of metals were prepared by oleic acid and oleylamine as reductive agent. The catalytic properties in hydrogenation of citral were evaluated. The results showed that the selectivity of citral to citronellal through hydrogenation of conjugated double bond could enhance eiher increasing the content of Ag or loading the bimetallic nanocrystals on the SnO₂. The selectivity of citronellal could reach to 96%. The increasing molar ratio Ag to Pd may change the electron structure of Pd Ag, which results the hydrogenation of citral selectively in conjugated double bond forming citronellal. Due to strong absorption of SnO₂ species to C=O bond, the PdxAg1-x supported on SnO₂ would contact with citral though the coordination of Pd Ag to conjugated C=C bond and SnO₂ to C=O. This effect may induce in the higher activity of conjugated C=C bond than the isolated C=C bond in hydrogenation of citral.