Novel nano-semiconductor film layer supported nano-Pd Complex Nanostructured Catalyst Pd/Ⓕ-MeOx/AC for High Efficient Selective Hydrogenation of Phenol to Cyclohexanone
Supported metal as a type of heterogeneous catalysts are the most widely used in industrial processes. High dispersion of the metal particles of supported catalyst is a key factor in determining the performance of such catalysts. Here we report a novel catalyst Pd/Ⓕ-MeOx/AC with complex nanostructured, Pd nanoparticles supported on the platelike nano-semiconductor film/activated carbon, prepared by the photocatalytic reduction method, which exhibited high efficient catalytic performance for selective hydrogenation of phenol to cyclohexanone. Conversion of phenol achieved up to more than 99% with a lower mole ratio (0.5%) of active components Pd and phenol within 2 h at 70 °C. The synergistic effect of metal nanoparticles and nano-semiconductors support layer and the greatly increasing of contact interface of nano-metal-semiconductors may be responsible for the high efficiency. This work provides a clear demonstration that complex nanostructured catalysts with nano-metal and nano-semiconductor film layer supported on high specific surface AC can yield enhanced catalytic activity and can afford promising approach for developing new supported catalyst.
Fabrication of Pd@N-doped porous carbon-TiO2 as a highly efficient catalyst for the selective hydrogenation of phenol to cyclohexanone in water
A highly efficient catalyst with the structure of semiconductor–metal heterojunction for phenol hydrogenation in water was fabricated by loading the Pd nanoparticles on the N-doped porous carbon-TiO2 (CN-TiO2) materials, which was synthesized via the one-step carbonization of TiO2-contained ZIF-67. The microstructures of the as-prepared Pd@CN-TiO2 catalysts were investigated in detail and the catalytic properties were tested by the phenol hydrogenation under mild conditions. With increasing TiO2 amount, the charge transfer and specific surface area of Pd@CN-TiO2 initially increase and then reduce, thereby the catalytic performance show a similar regular pattern. The as-fabricated Pd@CN-TiO2 exhibits a superior catalytic performance than the Pd nanoparticles supported on TiO2 or CN separately, owing to their synergistic effect. When the parameters affecting the catalytic efficiency are optimized, the conversion of phenol and selectivity for cyclohexanone can even achieve 98% in pairs with a higher reaction rate of 0.45 mmol h−1. Furthermore, the Pd@CN-TiO2 shows stable performance in the recycling experiments.
HPLC determination of chlorhexidine gluconate and p-chloroaniline in topical ointment.
A novel fast isocratic reversed-phase HPLC method for simultaneous determination of chlorhexidine and its degradation product p-chloroaniline was developed. Zorbax SB Phenyl column (75 mm x 4.6 mm, 3.5 microm) was used for the separation. Mobile phase composed of acetonitrile and buffer solution of 0.08 M sodium phosphate monobasic containing 5 ml of triethylamine (0.5%) and adjust with 85% phosphoric acid to pH 3.0 in ratio 35:65 (v/v) pumped isocratically at flow rate 0.6 ml min(-1) was used. UV detection was performed at 239 nm, the total analysis time was about 10 min. The method is suitable for practical routine analysis of topical ointment in the quality control laboratory.