Manhong Liu

Selective hydrogenation of o-chloronitrobenzene over polymer-stabilized ruthenium colloidal catalysts

The selective hydrogenation of ortho-chloronitrobenzene (o-CNB) to ortho-chloroaniline (o-CAN) was accomplished without dehalogenation over finely dispersed polyvinylpyrrolidone-stabilized ruthenium colloids (PVP–Ru). The influence of experimental parameters on reaction was also investigated. It was observed that some metal cations added to the system increased the activity while the selectivity remained constant.

An investigation of the interaction between polyvinylpyrrolidone and metal cations

Abstract The interaction between polyvinylpyrrolidone (PVP) and metal cations has been studied in absolute ethanol and water at room temperature and atmospheric pressure. The UV-VIS and IR absorption spectra of metal cations, PVP and PVP-M n + (M n + =Fe 3+ , Co 2+ , Ni 2+ ) were given. It was shown that PVP and metal cations formed unstable complexes, and the coordination stability constants were determined according to the Miller–Dorough method. The stability constants of PVP-Fe 3+ and PVP-Co 2+ were lower than 10 and 0.6, respectively, and that of PVP-Ni 2+ was too low to be estimated. The solid complexes of PVP-Fe 3+ and PVP-Co 2+ were also synthesized under proper conditions.

Selective hydrogenation of α, β-unsaturated aldehyde to α, β-unsaturated alcohol over polymer-stabilized platinum colloid and the promotion effect of metal cations

Abstract The modification of some metal cations to polymer-stabilized platinum colloid leads to remarkable increases in both the activity and the selectivity in liquid-phase selective hydrogenation of cinnamaldehyde to cinnamyl alcohol and of crotonaldehyde to crotyl alcohol. The promotion effect was due to the interaction of metal cations and the CO groups in reactants. The adsorbed metal cations activated the CO double bonds to accelerate the reaction rate and to increase the selectivity to α,β-unsaturated alcohols. The steric hindrance also played an important role in the reaction.

Immobilization of polymer-stabilized metal colloids by a modified coordination capture: preparation of supported metal colloids with singular catalytic properties

Abstract Polymer-stabilized metal colloids interact with various supports which have been pretreated with ethanol solution of triphenylphosphine (TPP), then the polymer and TPP are washed off with H 2 O and toluene/EtOH solvents sequentially, to give the supported metal colloids with the same size and size distribution as their precursor. The as-prepared supported platinum colloids exhibit superior catalytic properties to their precursor in selective hydrogenations of o -chloronitrobenzene to o -chloroaniline and citronellal to citronellol. This reveals the great potentiality of nanoscale metal colloids in catalysis.

Role of boron species in the hydrogenation of o-chloronitrobenzene over polymer-stabilized ruthenium colloidal catalysts

Abstract The role of boron species in selective hydrogenation of o-chloronitrobenzene (o-CNB) over polymer-stabilized ruthenium colloids has been studied. Of the two kinds of boron species (boride and borate) present in ruthenium colloids prepared by NaBH4 reduction, it was verified that only borate had a significant effect on the hydrogenation of o-CNB, while boride performed as a spectator. When metal cations were added into ruthenium colloidal catalyst system as modifiers, respectively, we observed that the synergetic effect between borate and metal cations occurred in these systems. It is suggested that metal complex ions were formed between the metal cations and borate ions.

Selective hydrogenation of citronellal to citronellol over polymer-stabilized noble metal colloids

Abstract Citronellal was hydrogenated to citronellol by polymer-stabilized Pt and Ru colloids. The metal cations increased both the activity and the selectivity of the colloids. The modification was assumed to be due to the adsorbed metal cations activating the CO double bonds, thus accelerating the reaction rate and increasing the selectivity to unsaturated alcohols.

Unexpected effects of trace impurities on the properties of polymer-stabilized ruthenium colloids from different sources of ruthenium(III) chloride hydrate

The stability and the catalytic performances of polyvinylpyrrolidone-stabilized ruthenium colloids (PVP-Ru) prepared by using RuCl(3).xH(2)O of different sources have been investigated. The trace impurity content of platinum and palladium in RuCl(3).xH(2)O was demonstrated to be the main factors affecting the properties of PVP-Ru colloids.