Support For Pt Catalyst Research Articles

Preparation of A New Carbon Nano-particle by Arc Discharge

AbstractSynthesis and characterization of a new carbon particle are investigated in this study. The carbon particle, which possesses a very high surface area (682 cm2/g), is suitable for catalysts loading in application of fuel cell. As well known, carbon materials are used to be a support of Pt catalyst to achieve high dispersion to enhance the activity of Pt. The synthesis was performed by conventional arc discharge process between two graphite electrodes in vacuum. A high-current range from 100∼ 300 ampere was utilized to evaporate the cathode electrode in order to produce carbon soot onto the wall of chamber, and further high production rate of 10 g/hr was achieved. The morphology and microstructure of the materials were investigated by SEM, HRTEM, XRD and Raman spectroscopy.Observations of the soot by SEM and HRTEM have shown that it consists agglomerations of carbon particles linked each other to form a chain-like structure. Most carbon particles are approximate 30 ∼ 60 nm in diameter. HRTEM observation reveals that a carbon particle is comprised of several defective onions with different diameters and extremely curled graphene sheets, which appear as double-sheet layers.

Preparation of Pt catalysts supported on activated carbon felts (ACF)

Activated carbon felts (ACFs) have been used as supports for Pt catalysts. The preparation was carried out by the impregnation method using chloroplatinic acid as metal precursor. The effect of impregnation time and surface chemistry of the support on the catalytic properties and the characteristics of the metallic phase have been investigated. Nitrobenzene (Nbz) hydrogenation in liquid phase at 25 °C and cyclohexane (CH) dehydrogenation in gas phase at 300 °C were used as catalytic tests. The state of platinum in reduced catalysts (at 100 and 350 °C) was studied by TPR and XPS. Oxygen surface groups only produce a slight effect on the catalytic properties. The use of low impregnation times (30 min) during the preparation of Pt/ACF leads to catalysts with Pt mainly deposited in the outer shell of the fibers, while at higher impregnation times, the metallic atoms seem to be deposited inside the pores. Pt(0) species appear in catalysts reduced at 100 °C by effect of the reducing properties of the carbon fiber exhibiting a considerable catalytic activity for Nbz hydrogenation.

Modification of carbon supported catalysts to improve performance in gas diffusion electrodes

The effect of surface oxidation of the carbon support of Pt catalysts with nitric acid has been investigated. Oxidation of the support before deposition of the Pt leads to a decrease in the Pt particle size, as reported by others, and enhanced performance for oxygen reduction in gas diffusion electrodes. Oxidation of the support after Pt deposition produces an even greater enhancement in performance, which we have attributed to enhanced proton conductivity in the catalyst layer. It is speculated that hydrophilic carboxylic acid groups produced by surface oxidation enhance wetting of the catalyst layer.

Synthesis of mesoporous zeolites and their application for catalytic conversion of polycyclic aromatic hydrocarbons

Three series of mesoporous aluminosilicate (Al-MCM-41) samples were synthesized using different aluminum sources including aluminum isopropoxide, pseudo boehmite and aluminum sulfate. Their catalytic activities were tested in the conversion of aromatic hydrocarbons including hydrocracking of 1,3,5-triisopropylbenzene, alkylation of naphthalene, and hydrogenation of naphthalene and phenanthrene. The three series of Al-MCM-41 samples behaved differently in acting as acidic catalysts and as supports. The Al-MCM-41 synthesized using aluminum isopropoxide was found to be the most promising acidic catalyst and good support for Pt catalyst.

Characterization by XPS and XAS of supported Pt/TiO2CeO2 catalysts

AbstractTiO2 and CeO2 are will known for inducing strong metal‐support interactions J(SMSI) of a different nature when used as supports for Pt catalysts. X‐ray photoelectron spectroscopy analysis of mixtures of TiO2CeO2 oxide supports (80:20 and 20:80) reveals at the surface a remarkable stabilization of cerium in the +3 oxidation state; the stabilization is more pronounced with lower cerium oxide concentration. X‐ray absorption spectroscopy measurements done on the LIII edge show the same variation as a function of cerium oxide concentration, but in the bulk the reduction is much lower. Cerium in Pt/TiO2CeO2 catalysts exhibits the same behaviour.