Pd-loaded Catalysts Research Articles

Effect of loading different transition metals W, Pt and Pd monolayers on quinoline hydrogenation and C–N bond cleavage over Mo2C(001)

Nitrogen-containing compounds such as quinoline in coal-based crude oils cause environmental pollution in the course of application. Consequently, dealing with the nitrogen-containing compounds from coal-based crude oil is of paramount importance. The hydrogenation and CN bond cleavage mechanisms of quinoline on the active Mo-terminated over Mo2C(001) surface, as well as on surfaces doped with W, Pt and Pd monolayers, were examined employing the density functional theory (DFT) method. The Pd and Pt-doped catalysts exhibited higher hydrogenation activity. The catalytic efficiency is enhanced by the loading of different metals, particularly with d-band center further away from the Fermi energy level. Additionally, a novel CN bond cleavage mechanism for quinoline has been proposed. The new proposed mechanism is more conducive for the CN bond cleavage. After a thorough comparison, the Pd-loaded catalyst was identified as the most effective for quinoline hydrogenation and CN bond cleavage.

Novel Pd-loaded self-standing hierarchical pore structure silicalite for low temperature toluene catalytic combustion

A novel Pd-loaded self-standing hierarchical pore structure silicalite were obtained by a handy polymer form board assisted hydrothermal method. The selected foam-shaped form board of a polyurethane (PU) foam monolith was regarded as the precursor of the self-standing hierarchical pore structure silicalite. The fruiting silicalite can steadily hold unique macroporous network structure and shape of the anterior original PU foam board . By means of the BET and BJH pore size distribution tests, the as-synthesis silicalite demonstrated hierarchical pore structure. The method of in-situ reduction was wielded to load palladium on the silicalite, and the catalytic performance of the catalyst to decompose toluene was tested at multiple burning temperatures. The experimental results revealed that the Pd-loaded catalyst can effectively decompose toluene at nearly 230°C, realizing low-temperature catalytic combustion of toluene.

Mechanistic Insight Into the Application of Alumina-Supported Pd Catalysts for the Hydrogenation of Nitrobenzene to Aniline.

Two Pd/γ-Al2O3 catalysts are examined for the vapor phase hydrogenation of nitrobenzene over the temperature range of 60–200 °C. A 1 wt % catalyst is selected as a reference material that is diluted with γ-alumina to produce a 0.3 wt % sample, which is representative of a metal loading linked to a candidate industrial specification aniline synthesis catalyst. Cyclohexanone oxime is identified as a by-product that is associated with reagent transformation. Temperature-programed infrared spectroscopy and temperature-programed desorption measurements of chemisorbed CO provide information on the morphology of the crystallites of the higher Pd loading catalyst. The lower Pd loading sample exhibits a higher aniline selectivity by virtue of minimization of product overhydrogenation. Reaction testing measurements that were undertaken employing elevated hydrogen flow rates lead to the proposition of separate reagent and product-derived by-product formation pathways, each of which occurs in a consecutive manner. A global reaction scheme is proposed that defines the by-product distribution accessible by the grades of catalyst examined. This information is helpful in defining product purification procedures that would be required in certain heat recovery scenarios connected with large-scale aniline production.

Dynamic behavior of Pd/Ca2AlMnO5+δ for purifying automotive exhaust gases under fluctuating oxygen concentration

Automotive exhaust gases containing harmful gases, such as hydrocarbons, CO, and NOx, are purified on a Pd-loaded catalyst. Since the purification efficiency depends on the oxygen concentration in the automotive exhaust gas, a material with a high oxygen storage performance is also essential for effectively purifying automotive exhaust gases. The present study demonstrates that the purification of the exhaust gases under fluctuating oxygen concentration proceeds efficiently on Pd/Ca2AlMnO5+δ which exhibits high oxygen release and storage capacities. Pd/Ca2AlMnO5+δ maintained reduction of NO to N2 for a longer time compared to conventional Pd/CeO2-ZrO2, under oxidative conditions. From the results obtained by combining operando and static X-ray absorption fine structure (XAFS) spectra, the valence state of the Mn species in the catalyst support was readily changed in response to the oxygen concentration in the exhaust gas, rather than that of the Pd species. In other words, the redox properties of the Mn species in Pd/Ca2AlMnO5+δ concern the NO reduction behavior under fluctuating oxygen concentration.

Layered PdW nanosheet assemblies for alcohol electrooxidation

Noble metal-based nanosheets are demonstrated as promising electrodes for energy electrocatalysis due to their remarkable advantages such as large surface area to volume ratio and high utilization efficiency of noble metals. In this work, three-dimensional layered palladium tungsten nanosheet assemblies (L-PdW NAs) have been successfully synthesized using a facile carbon monoxide (CO) confinement strategy, exhibiting much higher catalytic activity and stability toward both ethanol oxidation reaction (EOR) and methanol oxidation reaction (MOR) compared to palladium nanosheets (Pd NSs) and commercial Pd/C (Com Pd/C). It is discovered that the tungsten hexacarbonyl (W(CO)6) in the synthetic system displays a decisive key in forming the layered nanosheet structure. The catalytic enhancement mechanism should result the synergetic effects between the introduced W and novel architecture of layered nanosheet assembles. This work offers a low Pd loading, highly active and stable anode catalyst for direct alcohol fuel cells, while highlighting the beauty of the architecture with introduced W to significantly enhance the catalytic activity.

Enhanced catalytic activity and stability over P-modified alumina supported Pd for anthraquinone hydrogenation

Pd catalysts loaded on P-doped alumina (Pd/Al2O3-xP) were prepared and applied to H2O2 production by means of anthraquinone hydrogenation. The catalytic performance over Pd/Al2O3-xP catalysts showed a volcano-shape trend with phosphorus content. Pd/Al2O3-1P catalyst containing 1 wt% phosphorus exhibited the most excellent catalytic performance and reusability. The physicochemical properties of phosphorus-doped supports and Pd-loaded catalysts were investigated by several characterization methods. Doping phosphorus into Al2O3 increased thermal stability and adjusted surface acid intensity of the supports. Introducing suitable amount of phosphorus improved the Pd dispersion, regulated the reducibility of the catalysts. These factors contributed to the superior performance of Pd/Al2O3-1P for the anthraquinone hydrogenation reaction. Furthermore, Pd/Al2O3 catalyst gradually deactivated during the recycle test, which was mainly attributed to Pd loss and byproduct deposition on the catalyst. Incorporation of phosphorus could enhance the anchoring effect between Pd nanoparticle and support, which could also inhibit the generation of byproducts.

Facile fabrication of stable PdCu clusters uniformly decorated on graphene as an efficient electrocatalyst for formic acid oxidation

Small-sized nanocrystals uniformly distributed on suitable supports are promising as active electrocatalysts due to their unique electronic structure and high accessible surface area. Herein, we report the synthesis of graphene supported PdCu nanoclusters with a uniform size of 2.3 nm via a facile one-pot solvothermal method. This nanohybrid exhibits much higher inherent catalytic activity and stability for formic acid oxidation in comparison to graphene supported Pd clusters and commercial Pd/C. The PdCu nanoclusters can maintain their original size and dispersity on graphene even after 200 CV cycles. This work offers an efficient low Pd-loading catalyst for formic acid oxidation, and the synthetic approach is of significance to preparing uniform metal-based clusters decorated on supports with superior catalytic properties for fuel cells and sensors.

Pd/C catalyzed transfer hydrogenation of pyrolysis oil using 2-propanol as hydrogen source

The hydrodeoxygenation of guaiacol, as a pyrolysis oil representative model compound, was carried out over a Pd/C catalyst using a liquid hydrogen source of 2-propanol (2-PrOH) as an alternative to hydrogen gas. The effects of reaction temperature (190–230 °C), initial nitrogen pressure (0.5–12 bar), Pd loading amount (5 and 10 wt%), catalyst content (0.2–0.5 g), and reaction time (1–6 h) on the product distribution were investigated. Generally, 2-methoxycyclohexanone (two-oxygen-containing compound), methoxycyclohexane, cyclohexanol, 2-methyl-2-cyclohexen-1-ol, 2-cyclopenten-1-one, cyclohexanone, 2-cyclohexen-1-ol, phenol (one-oxygen-containing compounds), and (1-methylpropyl)cyclohexane (oxygen-free compound) were produced during the transfer hydrogenation of guaiacol in 2-PrOH. The feasibility of using different types of alcohols, primary (methanol, ethanol, 1-propanol, and 1-butanol) and secondary (2-propanol, and 2-butanol), as a substitute for hydrogen gas in the guaiacol hydrodeoxygenation process was examined, and it was found that only the secondary alcohols could act as a H-donor for the guaiacol transformation over Pd/C. Both 2-PrOH and 2-butanol (2-BuOH) led to almost complete conversion of guaiacol (≥98.5 wt%). However, complete deoxygenation of guaiacol to (1-methylpropyl)cyclohexane only occurred when 2-PrOH was used as the reducing agent. Finally, the transfer hydrogenation of raw pyrolysis oil was carried out over Pd/C at 230 °C and an initial nitrogen pressure of 8 bar for 4 h using 2-PrOH and 2-BuOH as the H-donors. Although 2-PrOH was the most efficient H-donor for guaiacol hydrodeoxygenation, 2-BuOH led to a higher level of deoxygenation of pyrolysis oil, resulting in a greater heating value.

Contribution of Different NbOx Species in the Hydrodeoxygenation of 2,5-Dimethyltetrahydrofuran to Hexane

Hydrodeoxygenation (HDO) is significant for the upgrading of biomass, bio-oil, and biomass-derived compounds to fuels due to their abundant oxygen atoms. It is reported that Pd, Pt supported on Nb-based materials is excellent for the HDO reaction of raw biomass and biomass-derived compounds because NbOx species has a strong ability to activate C–O bonds in the previous studies. Here, we try to clarify which are the active NbOx centers, isolated, oligomer or low-coordinated species by using Pd/Nb-doped SBA-15 as the catalyst and 2,5-dimethyltetrahydrofuran (DMTHF) as the model compound. Nb-doped SBA-15 with tunable Nb content is prepared by glycerol-assisted one-pot hydrothermal method. These Nb-doped SBA-15 and Pd-loaded catalysts are characterized by XRD, N2 sorption, TEM/SEM, diffuse reflectance ultraviolet–visible spectroscopy, and X-ray absorption near edge structure (XANES) spectroscopy. The performance of Pd/Nb-doped SBA-15 catalysts is found to be depended on the state of Nb species in SBA-15. The ...

Deposition of Pd nanoparticles on TiO2 using a Pd(acac)2 precursor for photocatalytic oxidation of CO under UV-LED irradiation

In this study, 0.1–4 wt.% Pd-loaded catalysts were synthesized via thermal decomposition of palladium (II) acetylacetonate (Pd(acac)2) at 210–310 °C or its photodecomposition under UV-LED irradiation using anatase TiO2 as a support. The catalysts were characterized by X-ray fluorescence, AAS, TEM, XPS, and CO chemisorption analyses and tested for CO oxidation at room temperature in a batch reactor both in the absence and presence of UV-LED irradiation. The effects of the Pd(acac)2 decomposition method and Pd content on the dark catalytic and photocatalytic activities were studied.Decomposition of Pd(acac)2 occurred with the formation of the metallic (Pd0) and oxidized (PdO) forms of palladium on the TiO2 surface for both employed methods. The photodecomposition resulted in an increased amount of metallic palladium. All of the synthesized Pd/TiO2 catalysts completely oxidized CO to CO2 at room temperature. UV-LED irradiation with a total irradiance of 10.4 mW/cm2 in the UVA region increased the rate of CO oxidation by up to 5 times compared to dark catalytic oxidation. Photodecomposition of Pd(acac)2 resulted in a higher activity of the Pd/TiO2 catalysts compared to the thermal decomposition method. The rate of CO oxidation under UV irradiation and under dark conditions monotonically increased as the Pd content increased due to the stability of high dispersion of Pd particles even with a high Pd content. The maximum value of the photonic efficiency was estimated to be 5.9%.CeO2, SiO2, and Al2O3 were also employed for the deposition of Pd to investigate the effect of a semiconducting support. For the CeO2-based catalyst, the activity under UV irradiation was higher than in the dark, but this effect was much lower compared to that of catalysts based on TiO2. By contrast, no substantial difference in the CO oxidation rate in the absence and presence of UV irradiation was observed for the non-semiconducting supports, SiO2 and Al2O3, confirming the photocatalytic oxidation of carbon monoxide for the TiO2- and CeO2-based catalysts.

Kinetics of CO Oxidation over Unloaded and Pd-Loaded α-Fe2O3 Spherical Submicron Powder Catalysts: Photoacoustic Investigations at Low Pressure

In this study, α-Fe2O3 spherical particles with an average diameter of approximately 200 nm were synthesized by a solvothermal method for use as both a catalyst and medium for a Pd catalyst. The kinetics of CO oxidation over powders of α-Fe2O3 spherical particles and 14 wt % Pd/α-Fe2O3 spherical particles were measured in a static reactor by using a CO2 laser-based photoacoustic technique. The total pressure was fixed at 40 Torr for the CO/O2/N2 mixture for temperatures in the range of 225–350 °C. The variation in the CO2 photoacoustic signal with the CO2 concentration during CO oxidation was recorded as a function of time, and the CO2 photoacoustic data at the early reaction stage was used to estimate the rates of CO2 formation. Based on plots of ln(rate) vs. 1/T, apparent activation energies were calculated as 13.4 kcal/mol for the α-Fe2O3 submicron powder and 13.2 kcal/mol for the 14 wt % Pd/α-Fe2O3 submicron powder. Reaction orders with respect to CO and O2 were determined from the rates measured at various partial pressures of CO and O2 at 350 °C. The zero-order of the reaction with respect to Po2 was observed for CO oxidation over α-Fe2O3 submicron powder, while 0.48 order to Po2 was observed for CO oxidation over Pd/α-Fe2O3 submicron powder. The partial orders with respect to PCO were determined as 0.58 and 0.54 for the α-Fe2O3, and the Pd/α-Fe2O3 submicron powders, respectively. The kinetic results obtained from both catalysts were compared with those for the α-Fe2O3 fine powder catalysts and were used to understand the reaction mechanism.

An effective low Pd-loading catalyst for hydrogen generation from formic acid

As an interesting hydrogen carrier, formic acid is bio-renewable, non-toxic and available in the liquid state at room temperature. The development of active and low-cost catalyst is of significance for hydrogen generation from formic acid. In this study, both a relatively cheap metal (Ag) and a functional support (nitrogen modified reduced graphene oxide, N-rGO) were applied to prepare Pd catalyst. It was found that the Ag atoms facilitated the formation of Pd-rich surface in the preparation strategy, in which the reductive N-rGO and a two-step feeding process of metal precursors played important roles. In addition, Ag additive was found to benefit catalyst stability. Most interestingly, the obtained low Pd-loading Pd1Ag6/N-rGO catalyst showed a specific Pd loading turnover frequency of 171 mol Pd−1 h−1 and a specific metal cost turnover frequency of 64.2 $−1 h−1, which were predominant among currently available Pd-based catalysts towards formic acid decomposition without any additive under room temperature.

Development of Low-Temperature Methane Gas Sensors By Using Cup-Stacked Carbon Nanofilament-Supported Pd Catalyst

Methane gas is found in environment, industrial and domestic areas. On the other hand, methane can cause explosions due to its inflammability. Thus, detection of methane gas in the environment is very important to avoid any accidental explosion. Catalytic combustion-type methane gas sensors can detect methane gas immediately. This type of methane gas sensors utilizes heat from catalytic combustion of methane by Pd-loaded catalysts. To indicate high catalytic activity, it is necessary for catalyst to heat around 250 ~ 600 °C because of thermochemical stability of methane. Consequently, electrical power consumption on the sensors is large. Hence development of efficient methane sensors that could work even at low temperatures is required. In this work, cup-stacked carbon nanofilament (CSCNF) was used for Pd support material. γ-Al2O3 was used for general catalytic combustion-type methane gas sensors. Relatively large amount of Pd is required to indicate catalytic activity in using γ-Al2O3 support. On the other hand, CSCNF has functional groups such as C=O carbonyl-type structures and C-O-C ether-type structures on its edge surface regularly. These functional groups interact with metallic ion in preparing catalysts by impregnating method. Therefore, Pd can be discretely distributed in small particles on the surface of CSCNF. CSCNF supported catalysts are considered to indicated high activity with even small amount of Pd. Therefore, low-temperature combustion of methane is expected. Moreover, sensors can detect heat of methane combustion immediately because CSCNF has good thermal conductivity. Catalytic activity of Pd/CSCNF was evaluated by temperature programmed reaction (TPR). This catalyst combusted 1 % methane in air at relatively low temperature 270 °C. Pd/γ-Al2O3, which was reference, combusted methane at 330 °C. CSCNF support was able to upgrade catalytic activity of Pd nanoparticles. Pd/CSCNF could reduce methane combustion temperature 60 °C lower than that of Pd/γ-Al2O3. It seems that CSCNF supported catalysts are attractive for methane combustion at low temperatures. CSCNF-loaded catalysts are more efficient for catalytic combustion-type methane gas sensors than the conventional sensors.

Synthesis of High Pd-Loaded Pd/C Catalyst Using Ultrasonic Dispersions for the Direct Formic Acid Fuel Cells

In recent years, direct formic acid fuel cells, DFAFCs, have received considerable attention for the power sources of the small electronic devices due to their high power density. Considering to the easy handling of the liquid fuel, we have considered that DFAFC can be promising power sources for stationary or transportation as well as the PEFC. However, the current power density of DFAFC has still far from that of PEFC. Therefore, the improvement of the power density is required. Moreover, improvement of the stability of the Pd catalyst is also required since Pd catalyst is poisoned by CO or CO species. In order to achieve high power density and good stability, a numerous catalyst supports, which contribute to the dispersion of the Pd catalyst and inhibit the Pd poisoning due to the interaction between Od and the supports, have been presented. This approach is quite available to solve the disadvantage of the DFAFC, however, it causes the increase of thickness of the anode catalyst layer since the Pd is usually loaded to the support around 20 wt% or less. Thick catalyst layer caused a mass transport limitation of the anode which significantly affects a performance of the DFAFC, therefore, the high Pd-loaded supported catalyst is required. When high Pd-loaded catalyst is prepared, the Pd nanoparticles is easy to agglomerate on the support resulting in the decrease of the electrochemical surface area. In this study, in order to fabricate the high Pd-loaded supported catalyst with well dispersions, we focused on the ultrasonic dispersions of the precursor and the catalyst supports before the chemical reduction. PdCl2 and the Vulcan XC-72 were used as the precursor and the supports, and the effects of the intensity and the time of the ultrasonication on the formic acid oxidation reaction, FAOR, activity, the BET surface area, ECSA and the crystallite diameter measured by XRD were investigated by fabricating Pd/C contained 20 wt % of Pd. From these results, the higher FAOR is obtained when the ultrasonication was conducted at appropriate intensity and time comparing the conventional Pd/C fabricated without ultrasonication. Based on the optimum ultrasonication conditions, Pd/C catalyst contained 50 wt% and 80 wt% of Pd catalyst were prepared. It was found that the Pd/Cs fabricated with ultrasonic dispersions showed much superior FAOR activity comparing to the Pd/Cs fabricated without ultrasonication although they showed a slight decrease of the FAOR activity per unit weight of Pd comparing to that of 20wt% Pd/C fabricated with ultrasonication. Form these results, the ultrasonic dispersion is quite important and the effective for the fabrication of high Pd-laded Pd/C catalyst.

Palladium nanoparticles supported on magnetic copper ferrite nanoparticles: The synergistic effect of palladium and copper for cyanation of aryl halides with K4[Fe(CN)6

In this paper, for the first time, palladium nanoparticles were supported on (3-aminopropyl) triethoxysilane-modified copper ferrite nanoparticles. The obtained catalyst was characterized using FT-IR, TEM, EDX, AAS, XRD, and TGA analyses. The prepared heterogeneous catalyst showed superior activity toward cyanation of aryl iodides and bromides with K4[Fe(CN)6] compared to the Fe3O4 supported palladium nanoparticles, unfunctionalized CuFe2O4 nanoparticles, homogeneous Pd(OAc)2, CuCl2, and CuI catalysts. The heterogeneous and low Pd loading catalyst was recycled for four consecutive runs with small drops in catalytic activity.

Influence of the template on the properties of SAPO-31 and performance of Pd-loaded catalysts for n-paraffin isomerization

The SAPO-31 silicoaluminophosphates were synthesized by using different di-alkylamines and their properties were characterized by XRD, SEM and N 2 adsorption. NH 3-TPD, IR spectroscopy of adsorbed pyridine and 29Si MAS NMR showed that these molecular sieves differed in their acidity both in the number of acid sites and in their strength. The catalytic properties of Pd/SAPO-31 samples were compared in n-decane conversion. It was found that their activity was related to the acidity of SAPO-31, but the isomerization selectivity was defined by the structural characteristics of the microporous material with minor influence of the other physico-chemical properties studied.

Highly selective hydrogenation of 3,4-dichloronitrobenzene over Pd/C catalysts without inhibitors

A series of Pd-only catalysts supported on activated carbon pretreated with HNO 3 or EDTA-2Na for liquid phase selective hydrogenation 3,4-dichloronitrobenzene (DCNB) to corresponding 3,4-dichloroaniline (DCAN) are investigated. Characterization of the catalysts is performed by N 2 adsorption/desorption, TPD, XRD and TPD techniques. The selectivity to DCAN is not only correlate with the Pd particle average size, but also correlate with distribution of Pd particles sizes. The surface groups of activated carbon can influence the average size and distribution of Pd particles. Pretreated activated carbon with HNO 3, forms various oxygen-containing groups on the surface, results in large average size but wide-distributed Pd particles. On the contrast, pretreated activated carbon with EDTA-2Na results in large average size and narrow-distributed of Pd particles simultaneously. More than 60% Pd particles sizes are distributed in the 20–30 nm range of the 2% Pd loading catalyst pretreated with 1 M EDTA-2Na, of which the selectivity to DCAN is up to 99.61%.

Oxidation characteristics of polycyclic aromatic hydrocarbons in flue gas over Pd/γ-Al 2O 3 catalyst

A series of Pd/γ-Al 2O 3 catalysts with various Pd loadings was prepared via incipient-wetness impregnation method under different synthesis conditions. The structural and textural properties of the synthesized catalysts were characterized by XRD, N 2 adsorption/desorption, TEM, H 2-TPR, and SEM-MAPS; their catalytic performance in the elimination of polycyclic aromatic hydrocarbons (PAHs) in coal-fired flue gas by oxidation was investigated. The results revealed that the PAHs removal efficiency over various Pd-loaded catalysts fluctuates between 67.3% and 93.5%; the conversion of PAHs increases with the Pd loading in the catalyst. Moreover, a better oxidation activity of these catalysts is observed for the PAHs with higher ring-cycles; nevertheless, the removal rates based on the toxicity equivalence quantity (TEQ) for all PAHs are higher than 90%. The Pd/γ-Al 2O 3 with a Pd loading of 0.2% and calcined at 600°C exhibits the best catalytic performance for PAHs oxidation, with a removal rate of 93.5% at 300°C.

Pd-loaded superparamagnetic mesoporous NiFe 2O 4 as a highly active and magnetically separable catalyst for Suzuki and Heck reactions

A superparamagnetic solid catalyst has been successfully synthesized by loading palladium nanoparticles into the pore network of a mesoporous NiFe 2O 4 support (Pd/NF300), which was used as a magnetically separable and highly active catalyst for Suzuki and Heck C–C coupling reactions. Various techniques were employed to characterize the synthesized NiFe 2O 4 supports and Pd-loaded catalysts. The Pd/NF300 catalyst showed high activity for both Suzuki and Heck reactions even under a very low Pd using amount (0.08 mol% Pd based on aryl halide). Moreover, the catalyst could be magnetically separated, recycled, and showed a very slight reduction in catalytic activity after five cycles. A synergetic catalytic effect between the well dispersed Pd 0 and the basic mesoporous structure of magnetic supports has been proposed to understand its greatly enhanced catalytic activities.

Methanol-Tolerant Oxygen Reduction Reaction at Pt–Pd/C Alloy Nanocatalysts

Carbon-supported platinum and Pt–Pd alloy electrocatalysts with different Pt/Pd atomic ratios were synthesized by a microemulsion method at room temperature (metal loading is 10 wt %). The Pt–Pd/C bimetallic catalysts showed a single-phase fcc structure and the mean particle size of Pt–Pd/C catalysts was found to be lower than that of Pt/C. The methanol-tolerant studies of the catalysts were carried out by activity evaluation of oxygen reduction reaction (ORR) on Pt–Pd catalysts using a rotating disk electrode (RDE). The studies indicated that the order of methanol tolerance was found to be PtPd3/C>PtPd/C>Pt3Pd/C. The oxygen reduction activities of all Pt–Pd/C were considerably larger than that of Pt/C with respect to onset and overpotential values. The Pd-loaded catalysts shift the onset potential of ORR by 125 mVMSE, 53 mVMSE, and 41 mVMSE to less cathodic potentials for Pt3Pd/C, PtPd/C, and PtPd3/C, respectively, with reference to Pt/C and the Pt3Pd/C catalyst showed greater shift in the onset value than the other PtPd catalysts reported in literature. Moreover, the Pt–Pd/C catalysts exhibited much higher methanol tolerance during ORR than the Pt/C, assessing that these catalysts may function as a methanol-tolerant cathode catalysts in a direct methanol fuel cell.