STUDIES ON THE STATE OF PALLADIUM AND HYDROGENATION ACTIVITY OF RESIN SUPPORTED PALLADIUM──TIN OXIDE CATALYSTS

Several Pd--SnO2/ D3520 and Pd--PbO / D3520 catalysts with Pd/ D3J20, SnO2 / D3520 and PbO / D3520 catalysts as rference were studied by means of IR and XPS. Interaction between Pd and the second metal or between metal and support was observed. Results show that there is a strong interaction between Pd and the second metal, but there is not an obvious interaction between metal and support. The active constituent is Pd￣0. Hydrogenation activity of the catalysts is altered because of the interaction between Pd and the second,metal.The activity of the catalysts for hydrogenation has relation to outer layer valence electron density of Pd.

Preparation of Ni/bentonite catalyst and its applications in the catalytic hydrogenation of nitrobenzene to aniline

Ni supported on bentonite was prepared by the impregnation method with different nickel contents, applied to the hydrogenation of nitrobenzene to aniline in a fixed-bed reactor, and it was characterized by X-ray diffraction（XRD）, H2-temperature programmed reduction（H2-TPR）, and X-ray photoelectron spectrometry（XPS）. The results showed that Ni/bentonite catalyst with 20 wt% nickel content provided a higher conversion of nitrobenzene and selectivity of aniline compared to other catalysts. NiO was the precursor of the active component of the catalyst, and the small crystallite size as well as the highly dispersed NiO on the Ni/bentonite-20 catalyst, contributed to the catalytic performance. The hydrogenation of nitrobenzene was carried out at 300℃ with a H_2 gaseous hourly space velocity of 4800 ml·（g cat）^-1·h^-1and a nitrobenzene liquid hourly space velocity of4.8 ml·（g cat）^-1·h^-1 over Ni/bentonite-20. A 95.7% nitrobenzene conversion and 98.8% aniline selectivity were obtained. While the nitrobenzene liquid hourly space velocity was 4.8 ml·（g cat）^-1·h^-1, the yield of aniline was more than 95.0% during a 10-hour reaction.

Pd/TiN nanocomposite catalysts for selective hydrogenation of phenol and its derivatives

Pd/TiN nanocomposite catalysts were fabricated for one-step selective hydrogenation of phenol to cyclohexanone successfully. High conversion of phenol （99%） and selectivity of cyclohexanone （98%） were obtained at 30 ℃ and 0.2 MPa H2 for 12 h in the mixed solvents of H20 and CH2C12. The Pd nanoparticles were stable in the reaction, and no aggregation was detected after four successive runs. The catalytic activity and selectivity depended on slightly the Pd particle sizes. The generality of the catalysts for this reaction was demonstrated by the selective hydrogenation of phenol derivatives, which showed that the catalyst was selective for the formation of cyclohexanone.

Preparation,Characterization and Application of Polyaniline/Epoxide Polysiloxane Composite Films

Composites of polyaniline（PAn） and epoxide polysiloxane（EPSi） are reported for the first time. EPSi is designed, synthesized and N-grafted onto the PAn backbone through covalent bonds. As-prepared EPSi-g-PAn composites are soluble in organic solvents and the corresponding films can be easily produced via a simple solution-casting procedure. The composite films combine the mechanical characteristics of EPSi and the chemical properties of PAn, enabling the facile introduction of the noble metal particles. The successful fabrication of the composites is confirmed by the investigation of the molecular structure, crystalline structure and microstructure of the materials. The resulting composite films containing noble metal particles are employed as the catalysts for the hydrogenation of phenol to produce cyclohexanone, which exhibit the convenience and recyclability for usage as well as the high catalytic activities, including the conversion ratio of 97%-100% and the selectivity as high as 84%-98%. The present work not only provides a new method to improve the processability of the conducting polymers but also describes a kind of composite materials that may display outstanding preformances in industrial catalysis.