One-step synthesis of carbon-supported Pd–Pt alloy electrocatalysts for methanol tolerant oxygen reduction

A facile, one-step reduction route was developed to synthesize Pd-rich carbon-supported Pd–Pt alloy electrocatalysts of different Pd/Pt atomic ratios. As-prepared Pd–Pt/C catalysts exhibit a single phase fcc structure and an expansion lattice parameter. Comparison of the oxygen reduction reaction (ORR) on the Pd–Pt/C alloy catalysts indicates that the Pd₃Pt₁/C bimetallic catalyst exhibits the highest ORR activity among all the Pd–Pt alloy catalysts and shows a comparative ORR activity with the commercial Pt/C catalyst. Moreover, all the Pd–Pt alloy catalysts exhibited much higher methanol tolerance during the ORR than the commercial Pt/C catalyst. High methanol tolerance of the Pd–Pt alloy catalysts could be attributed to the weak adsorption of methanol induced by the composition effect, to the presence of Pd atoms and to the formation of Pd-based alloys.     

High catalytic activity of ultrafine nanoporous palladium for electro-oxidation of methanol, ethanol, and formic acid

Nanoporous palladium (NPPd) with ultrafine ligament size of 3–6 nm was fabricated by dealloying of an Al–Pd alloy in an alkaline solution. Electrochemical measurements indicate that NPPd exhibits significantly high electrochemical active specific surface area (23 m² g⁻¹), and high catalytic activity for electro-oxidation of methanol, ethanol, and formic acid. Mass activities can reach 149, 148, 262 mA mg⁻¹ for the oxidation of methanol, ethanol and formic acid, respectively. Moreover, superior steady-state activities can be observed for all the electro-oxidation processes. NPPd will be a promising candidate for the anode catalyst for direct alcohol or formic acid fuel cells.     

Electrooxidation of Methanol on Platinum–Ruthenium Catalysts Applied to a Cation-Exchange Membrane

Possibilities for production of active Pt–Ru electrodes for the direct methanol fuel cell with a decreased content of platinum-group metals in them are studied. Platinum and ruthenium are electrodeposited on a thin layer of carbon black applied to a Nafion 117 membrane. The deposition potential effect on the specific surface area of the catalyst and its electrochemical activity in the methanol oxidation is studied. The oxidation currents are related to unit true surface area or unit catalyst mass. The dependence of activity on the Pt : Ru ratio in the plating solution and in the deposit is studied. The effect of the catalyst amount deposited and the particle size on the activity is studied. It is shown that the catalytic activity decreases at the average diameter of Pt–Ru particles less than 4 nm. The results are compared with the size effects observed earlier.     

Reaction of 1-bromo-2-acylacetylenes with thiobenzhydrazide

Conclusions The reactions of 1-bromo-2-acylacetylenes with thiobenzhydrazide at from –10 to –30°C in ether, acetonitrile, methanol without catalyst, or methanol in the presence of triethylamine gave 2-acylmethyl-5-phenyl-1,3,4-thiadiazoles and their hydrobromide salts.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2637–2638, November, 1988.     

Interactions of water and methanol with a mixture of copper and zinc metals: a theoretical <Emphasis Type="Italic">ab initio</Emphasis> study

Ab initio cluster quantum chemical calculations at the Hartree–Fock and second-order Møller–Plesset perturbation theory levels were carried out to mimic the interactions of water and methanol with a mixture of Cu and Zn metals. It was shown that both molecular and dissociative adsorption of methanol on a mixture of Cu and Zn metal catalyst are preferred over the corresponding adsorptions of water. Estimated transition-state structures for dissociation of methanol into CH·₃ and OH· lie about 9.0 and 22.0 kcal/mol higher compared to the dissociated (forward reaction) and molecular adsorption (reverse reaction) complexes, respectively. Based on distinct radicals' bond energies with the active sites of the catalyst considered, it is suggested that hydrogen molecules could be formed through a chain of homogeneous reactions of methyl radicals released into the gas phase with the water and/or methanol molecules.     

Study of Methanol Conversion over Fe-Zn-Zr Catalyst

The methanol conversion over Fe-Zn-Zr catalyst was studied at 0.1 MPa and 280-360℃. The experimental results indicate that the main products of methanol conversion are methane and butane, and that other hydrocarbons are scarcely produced.All results show that propylene is most probably the olefin formed first in methanol conversion rather than ethene over Fe-Zn-Zr catalyst.Methane is formed from methoxy group,and C_4 is possibly yielded on the surface from propylene through binding with a methoxy group.     

Methanol Decomposition in a Water–Methanol Equimolar Mixture on a Nickel-Promoted Copper–Zinc–Cement Catalyst

Methanol decomposition in a water–methanol equimolar mixture is studied in the presence of a nickel-promoted copper–zinc–cement catalyst. Methanol decomposition at 200–300°C on the oxide and reduced forms of the catalyst yields a gas with an H₂/CO ratio close to two. The use of an equimolar CH₃OH–H₂O mixture under analogous conditions enables obtaining gaseous products with a hydrogen concentration up to 75 vol %.     

Oxidation of Methanol on Pt,Pt–Ru,and Pt–Ru–Mo Electrocatalysts Dispersed in Polyaniline: An in situ Infrared Reflectance Spectroscopy Study

The electrochemical oxidation of methanol was investigated on a Pt–Ru–Mo catalyst with an in situ infrared reflectance spectroscopy. The electrocatalysts were prepared by an electrochemical deposition and dispersed in a conducting three-dimensional matrix of polyaniline (PAni). We observed that CO₂ is produced from methanol oxidation at 350 mV vs. RHE on PAni/Pt–Ru–Mo, which is 100 mV less negative than on PAni/Pt–Ru and 200 mV less than on PAni/Pt. The results suggest that Pt–Ru–Mo is less sensitive to CO_ADS poisoning than Pt–Ru and much more sensitive than Pt. Large differences are observed concerning the average wavenumber of _ADS between Pt–Ru–Mo, Pt–Ru, and Pt.     

Methanol synthesis from CO2-H2 and from CO-H2 under atmospheric pressure over Pd and Cu catalysts

Under atmospheric pressure, methanol was produced from CO₂–H₂ over Pd/ZnO and from CO–H₂ over Pd/MgO catalyst. Similar support effects were observed over Cu catalysts.     

Highly efficient Pt/TiO2 photocatalyst prepared by plasma-enhanced impregnation method

Highly efficient Pt/TiO₂ photocatalyst has been prepared using plasma-enhanced impregnation method. Impregnated 0.5 wt%Pt/TiO₂ was treated by plasma followed with thermal calcinations and hydrogen reduction. The catalyst characterizations show that Pt is highly dispersed with a size of 3–5 nm. UV–Vis reflection spectrum suggests it a high photosensitivity in near UV region. Such plasma prepared catalyst exhibits a much higher activity and better metal stability for hydrogen generation from methanol/water mixture, compared to the catalyst prepared conventionally. This highly efficient photocatalyst should have extensive applications in photocatalytic processes.