Performance of palladium-containing supported catalysts in the oxidation of 1-butene

Performance of palladium-containing supported catalysts in the oxidation of 1-butene was investigated in a fixed-bed flow microreactor. The Pd-Fe-HCl/Ti-Al catalyst is the best among the five Pd-Fe-HCl/X (A = SiO2, gamma-Al2O3, Al-Ti, TiO2, MCM-22) catalysts for the oxidation of I-butene to butanone. It is interesting that high propionic acid selectivity can be obtained when V and H2SO4 are added to the palladium-containing supported catalysts.

固相反应法制备的Pd/C催化剂对甲酸氧化的电催化活性

催化剂中Pd粒子的粒径和相对结晶度对甲酸氧化峰峰电位基本没有影响.但在Pd/C-1和Pd/C-2催化剂电极上主要氧化峰峰电流分别为17·1和6·1mA/cm2,表明Pd/C-1催化剂对甲酸氧化的电催化活性要高于Pd/C-2催化剂,这是由于Pd/C-1催化剂中Pd粒子的平均粒径和相对结晶度比Pd/C-2催化剂的小而引起的.图3为Pd/C-1和Pd/C-2催化剂电极在0·5mol/LH2SO4+0·5mol/L HCOOH溶液中,电位恒定在0·1V时的计时电流曲线.由图可见,在Pd/C-1催化剂电极上(图3,曲线a),当电位恒定在0·1V下扫描1000s时,电流密度为2·35mA/c

Synthesis of isomeric bis(amine anhydride)s for novel poly(amine imide)s by Pd-catalyzed amination of 4-chlorophthalic anhydride

Two novel bis(amine anhydride) monomers, N,N'-bis(3,4-dicarboxyphenyl)-1,4-phenylenediamine dianhydride I and N,/N'-bis(3,4-dicarboxyphenyl)-1,3-phenylenediamine dianhydride 11, were prepared via palladium-catalyzed amination reaction of 4-chloro-N-methylphthaliniide with 1,4-phenylenediamine or 1,3-phenylenediamine, followed by alkaline hydrolysis of the intermediate bis(amine imide)s and subsequent dehydration of the resulting tetraacids. A series of new poly(amine imide)s were prepared from the synthesized dianhydride monomers with various diamines in NMP via conventional two-step method.

Carbon-supported Pd nanocatalyst modified by non-metal phosphorus for the oxygen reduction reaction

A carbon-supported palladium catalyst modified by non-metal phosphorus(PdP/C) has been developed as an oxygen reduction catalyst for direct methanol fuel cells.The PdP/C catalyst was prepared by the sodium hypophosphite reduction method. The as-prepared Pd nanoparticles have a narrow size distribution with an average diameter of 2 nm. Energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) results indicate that P enters into the crystal lattice of Pd and forms an alloy.

Hydrogenation of o-chloronitrobenzene to o-chloroaniline over Pd/C in supercritical carbon dioxide

Hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN) with Pd/C has been investigated in supercritical carbon dioxide (scCO(2)) at 308 K. The influences of several parameters such as CO2, H-2 pressures, Fd metal particle size and reaction time have been discussed. CO2 pressure presented markedly effects on the reaction rate and product selectivity under the reaction conditions used, the selectivity to o-CAN at CO2 pressure from 8 to 13 MPa (supercritical region) was larger than that at CO2 pressure below 6 MPa (subcritical region).

Crystallographic and electrochemical characteristics of Ti-Zr-Ni-Pd quasicrystalline alloys

Ti45Zr35Ni20-xPdx (x = 0, 1, 3, 5 and 7, at%) alloys were prepared by melt-spinning. The phase structure and electrochemical hydrogen storage performances of melt-spun alloys were investigated. The melt-spun alloys were icosahedral quasicrystalline phase, and the quasi-lattice constant increased with increasing x value. The maximum discharge capacity of alloy electrodes increased from 79 mAh/g (x = 0) to 148 mAh/g (x = 7). High-rate dis-chargeability and cycling stability were also enhanced with the increase of Pd content. The improvement in the electrochemical hydrogen storage characteristics may be ascribed to better electrochemical activity and oxidation resistance of Pd than that of Ni.

Kinetic study of formic acid oxidation on carbon supported Pd electrocatalyst

The oxidation of formic acid at the Pd/C catalyst electrode is a completely irreversible kinetic process with the reaction order of 1.0. The oxidation rate of formic acid is increased with increasing the concentration of formic acid and is decreased with increasing H+ concentration. The apparent negative reaction order with respect to H+ is about -0.18 or -0.04 in H2SO4 or HClO4 solution respectively, because bisulfate anions would inhibit formic acid oxidation at some extent. The kinetic parameters, charge transfer coefficient and the diffusion coefficient of formic acid were obtained under the quasi steady-state conditions.

Guanidine/Pd(OAc)(2)-catalyzed room temperature Suzuki cross-coupling reaction in aqueous media under aerobic conditions

A highly efficient Pd(OAc)(2)/guanidine aqueous system for the room temperature Suzuki cross-coupling reaction has been developed. The new water-soluble and air-stable catalyst Pd(OAc)(2)(.)(1f)(2) from Pd(OAc)(2) and 1,1,3,3-tetramethyl-2-n-butylguanidine (1f) was synthesized and characterized by X-ray crystallography. In the presence of Pd(OAc)(2)(.)(1f)(2), coupling of arylboronic acids with a wide range of aryl halides, including aryl iodides, aryl bromides, even activated aryl chlorides, was carried out smoothly in aqueous solvent to afford the cross-coupling products in good to excellent yields and high turnover numbers (TONs) (TONs up to 850 000 for the reaction of 1-iodo-4-nitrobenzene and phenylboronic acid). Furthermore, this mild protocol could tolerate a broad range of functional groups.