Small Amount Of Pd Research Articles

Pd‐Doped In2O3 for CO2 Electroreduction to Ethanol through CO Binding Regulation

AbstractRenewable energy driven electrochemical carbon dioxide reduction (CO2RR) to alcohols provides an effective pathway for achieving carbon neutrality and sustainable development. However, it is challenging to convert CO2 into ethanol due to the sluggish C−C coupling and complex 12 electron/proton transferred process, which has been achieved mainly on Cu catalysts but with poor selectivity. Herein, In2O3 catalysts were doped with small amount of Pd and exhibited high activity for CO2RR to ethanol with a high Faradaic efficiency (50.7 %) at low overpotential. The introduction of Pd promotes the transformation of reaction products from formic acid to ethanol by modulating the binding strength of *CO intermediates. The in‐situ ATR‐SEIRAS and DFT calculations proved that the formation of Pd−O−In could modulate the binding strength of *CO and enhanced its coverage, thus facilitating C−C coupling step towards ethanol. This study may provide a new strategy to the generation of high value‐added products from CO2 over Non‐Cu‐based catalysts.

Highly Active and Dispersed Pd Nanoparticles Stabilized by Lacunary Phosphomolybdate: Synthesis, Characterization, and Liquid Phase Hydrogenation of Levulinic Acid to γ-Valerolactone

In the current scenario, one of the crucial reaction conversions is the synthesis of renewable biofuels and value-added chemicals from the hydrogenation of biomass. Therefore, in the present work, we are proposing aqueous phase conversion of levulinic acid to γ-valerolactone via hydrogenation using formic acid as a sustainable green hydrogen source over a sustainable heterogeneous catalyst. The catalyst based on Pd nanoparticles stabilized by lacunary phosphomolybdate (PMo11Pd) was designed for the same and characterized by EDX, FT-IR, 31P NMR, powder XRD, XPS, TEM, HRTEM, and HAADF-STEM analyses. A detailed optimization study was done to achieve maximum conversion (95% conversion), using a very small amount of Pd (1.879 × 10-3 mmol) with notable TON (2585) at 200 °C in 6 h. The regenerated catalyst was found to be workable (reusable) up to three cycles without any change in activity. Also, a plausible reaction mechanism was proposed. The catalyst exhibits superior activity against reported catalysts.

Selective adsorption of Pd(II) over Ag(I) in nitric acid solutions using nitrogen-donor-type adsorbents

The HNO3 leaching process is used in recycling Pd metal from spent products that primarily contain Ag, and most Pd residues are separated from solutions containing Ag(I). However, a small amount of Pd(II) remains in these Ag(I) solutions. Therefore, the separation of Pd(II) and Ag(I) in HNO3 solutions is essential for promoting efficient Pd recycling. In this study, the separation of Pd(II) and Ag(I) in HNO3 solutions was investigated using four N-donor-type adsorbents bearing amine (R-Amine), iminodiacetic acid (R-IDA), pyridine (R-Py), and bis-picolylamine (R-BPA) functional groups. R-IDA and R-Py demonstrated efficient separation of Pd(II) (82 %–99 %) from Ag(I), Cu(II), Ni(II), and Fe(III) (<3%) over a range of HNO3 concentrations (0.5–7 M for R-IDA and 0.3–7 M for R-Py). R-Amine showed similar selectivity but lower Pd(II) adsorption (<65 %). By contrast, R-BPA adsorbed Pd(II), Ag(I), and Cu(II) efficiently and non-selectively (>90 %; 0.3–5 M HNO3). Structural analyses of the adsorbed metal ions using Fourier-transform infrared and extended X-ray absorption fine structure spectroscopies revealed the separation mechanisms of the N-donor-type adsorbents. Pd(II) adsorption on R-IDA, R-Py, and R-BPA occurred via Pd(II) coordination with their respective functional groups, whereas that on R-Amine occurred via anion exchange of NO3− with [Pd(NO3)4]2−. The coordinative adsorption mechanisms resulted in higher Pd(II) adsorption of R-IDA, R-Py, and R-BPA. HCl (5.0 M) eluents desorbed 83 % of Pd(II) from R-IDA, whereas thiourea eluents (0.1 M) desorbed 95 % of Pd(II) from R-Py. R-Py was the most effective Pd(II) adsorbent based on adsorption selectivity and desorption efficiency.

Recovery of Palladium Metal with High Purity by Selective Reduction from Inorganic Acid Leaching Solutions of Cemented Zinc

A small amount of Pd(II) present in spent electroplating solutions is concentrated by cementation. In this work, a process was developed to recover pure palladium metal by selective reduction from the hydrochloric and the sulfuric acid leaching solutions of cemented zinc. For this purpose, hydrazine and ascorbic acid were employed as reducing agents and the effect of several variables such as the acidity of the leaching solutions, molar ratio of reducing agents to Pd(II), reaction time and temperature was investigated. Since neither of the reducing agents can reduce Pd(II) from strong acidic solutions, it was necessary to decrease the acidity of the leaching solutions by dilution with distilled water. Our results indicated that it was possible to recover Pd metal with high purity by selective reduction after diluting the hydrochloric and sulfuric acid leaching solutions of cemented zinc with distilled water. When the molar ratios of the reducing agents to Pd(II) were the same, the reduction percentage of Pd(II) from the sulfuric acid solution was higher than that from the hydrochloric acid solution, due to the much higher complex formation constant of PdCl42- than Pd(SO4)22-. The reduction of Pd(II) by hydrazine occurred within 15 mins at room temperature, while a higher temperature (60 oC) and longer reaction time (1h) were necessary to reduce Pd(II) with ascorbic acid. The reduction of Pd(II) from sulfuric acid solution was more efficient than from hydrochloric acid solution. It was possible to recover Pd metal with high purity from the leaching solution of cemented zinc using the reduction method.

Effect of Ethylene Glycol on the Dissolution of Palladium with HCl Solution Containing Oxidizing Agents and Selective Precipitation of Pd(IV) Compound

There is growing interest in the recovery of pure palladium (Pd) compound from cemented Pd from spent electroplating solutions due to increasing demand for Pd, and there is considerable motivation to develop an efficient recovery process. In conventional methods of leaching Pd metal, HCl solutions containing oxidizing agents are employed. In this work, ethylene glycol (EG) replaced water as a diluent in the HCl solution containing oxidizing agents such as H2O2, NaClO and NaClO3. Leaching of the Pd metal and the subsequent precipitation of the Pd(IV) compound was investigated. Among the three kinds of oxidizing agent, NaClO3 showed the best Pd metal leaching efficiency from a metallic mixture of Pd and Zn from HCl in EG solution. The role of EG in enhancing the leaching and precipitation is discussed in light of its interaction with other components in the solutions. To precipitate the Pd(IV) compound with NH4Cl, it is important that the dissolved Pd ion exists as Pd(IV). Therefore, NaClO3 was again added to the leaching solution to verify the oxidation of Pd(II) to Pd(IV). Extra pure ammonium hexachloropalladate ((NH4)2PdCl6) was recovered by precipitation from the leaching solution of the cemented Pd under the optimum conditions. Compared to conventional HCl systems, the present process shows some advantages, by reducing both chemical dosage and energy consumption. The results confirm a process can be developed for the recovery of the Pd(IV) compound from spent electroplating solutions containing a small amount of Pd(II).

Separation of Pd(II) and Zn(II) from Sulfuric Acid Solution by Commercial Extractants

Spent electroplating solutions contain a small amount of Pd(II). This Pd(II) can be concentrated by cementation with zinc metal powder. In order to recover pure palladium, a hydrometallurgical process consisting of leaching followed by solvent extraction was developed in this work. First, suitable extractants for the selective extraction of Pd(II) over Zn(II) were selected from synthetic sulfuric acid solutions. Among cationic, solvating and basic extractants employed in this work, Cyanex 301, LIX 63 and Aliquat 336 showed selectivity for Pd(II) over Zn(II) from 5 M sulfuric acid solutions. Stripping results for the loaded phases of these three extractants showed that HCl was effective at stripping Pd(II) from the loaded LIX 63 and Aliquat 336, while a mixture of inorganic acid and NaClO as an oxidizing agent was necessary to strip Pd(II) from the loaded Cyanex 301. The cemented Pd was completely dissolved using 5 M sulfuric acid solution at 25 oC, and the concentration of Pd(II) and Zn(II) in the real leaching solution was 1.926 and 0.074 g/L, respectively. Application of the optimum conditions for the selective extraction of Pd(II) over Zn(II) to the real sulfuric acid leaching solution of cemented Pd indicated that only LIX 63 and Cyanex 301 could separate Pd(II) from Zn(II). The stripping efficiency of Pd(II) by a mixture of 5 M HCl and 3% NaClO was much higher from the loaded LIX 63 than from the loaded Cyanex 301. Considering the extraction and stripping characteristics of Pd(II), LIX 63 was selected as an optimum extractant for the separation of Pd(II) from the real sulfuric acid leaching solution of cemented Pd.

Enhanced Catalytic Denitrification Performance of Ruthenium-based Catalysts by Hydrogen Spillover from a Palladium Promoter

Catalytic denitrification, a promising technology for nitrate removal, is increasingly limited by the rising price of Pd. Replacing Pd with less-expensive Ru would significantly reduce the cost; however, Ru-based catalysts have been reported to perform inconsistently in denitrification applications, making their replacement prospects unclear. Herein, the surface oxidation of Ru catalysts was confirmed to be a key factor that inhibits activity. A series of Ru-Pd catalysts containing small amounts of Pd (0.5 wt%) was developed to eliminate the Ru surface-oxide layer through the spillover of hydrogen atoms activated on the Pd promoter. Ru-Pd/Fe3O4 exhibited superior catalytic activity to Ru-Pd/C and Ru-Pd/Al2O3 because the reducible carrier (Fe3O4) has a lower resistance to hydrogen spillover and diffusion, as determined experimentally and supported by density functional theory calculations. This study developed a method that eliminates ruthenium surface oxides in situ and restores its denitrification activity, further reducing the barrier to Ru replacing Pd in catalytic aqueous denitrification.

2D covalent organic framework: a photoactive heterogeneous catalyst for chemical fixation of CO2 over propargyl amines in water under sunlight

We have demonstrated the efficient synthesis of Pd(II)-based 2D mesoporous covalent organic framework (COF) along with a small amount of Pd(0), which is characterized by different characterization tools. These studies suggest that this material with low bandgap energy (Eg) of 1.73 eV can exhibit great photocatalytic activity toward CO2 fixation reaction. Therefore, we have applied the Pd(II)-loaded COF as a new and effective photocatalyst for the preparation of oxazolidinone through the chemical fixation of CO2. The reaction takes place in green solvent (H2O) in absence of any base and under the sunlight at atmospheric pressure of CO2 without using any cocatalyst. The reaction does not happen in the dark. In this context, we showed that a turnover number (TON) of 3.392 × 103 can be achieved using the catalytic cycle under sunlight. The light dependency of the reaction is also checked by a control experiment via light modulation between light on and off. Furthermore, the catalyst shows efficient reusability for multiple reaction cycles, and also the heterogeneity test of the material suggests minimal active metal leaching during the catalysis reaction cycles. These results for the photocatalytic synthesis of oxazolidinone by CO2 incorporation over COF under sunlight open a new environment-friendly green pathway for the formation of oxazolidinones.

Leaching of a Mixture of Palladium and Zinc Metal Using Hydrochloric and Sulfuric Acid Solutions

Spent electroplating solutions contain small amounts of Pd(II). Cementation of Pd(II) with zinc metal powder is practiced to concentrate the Pd. Dissolution of the cemented Pd metal is necessary to recover pure Pd metal or compounds. In this work, the leaching behavior of Pd metal in inorganic acid solutions (hydrochloric and sulfuric acid) in the presence of an oxidizing agent such as H2O2, NaClO3, or NaClO was investigated. To determine the optimum conditions for Pd leaching, experiments were conducted by adjusting the concentration of the acids and oxidizing agents, reaction temperature and time, and pulp density. Complete leaching of Pd was possible using a hydrochloric acid solution with 3 kinds of oxidizing agents, whereas only NaClO was effective in the leaching with sulfuric acid solution. The chloride ions of HCl and NaClO3/NaClO play an important role in enhancing the leaching of Pd, due to the formation of Pd chlorocomplexes and by decreasing the reduction potential of Pd(II). Compared to H2O2, NaClO3 and NaClO showed some merits as oxidizing agents in terms of reaction time, temperature and low acid concentration. Based on the optimum leaching conditions of single Pd metal, the conditions for the complete leaching of Pd and Zn from the metallic mixtures were obtained.

Synthesis and characterization of supported stabilized palladium nanoparticles for selective hydrogenation in water at low temperature.

Zirconia supported vacant phosphotungstate stabilized Pd nanoparticles (Pd–PW11/ZrO2) were prepared using a simple impregnation and post reduction method, characterized and their efficiency for selective C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> C hydrogenation of unsaturated compounds explored. The establishment of a hydrogenation strategy at low temperature using water as solvent under mild conditions makes the present system environmentally benign and green. The catalyst shows outstanding activity (96% conversion) with just a small amount of Pd(0) (0.0034 mol%) with high substrate/catalyst ratio (29 177/1), TON (28 010) and TOF (14 005 h−1) for cyclohexene (as a model substrate) hydrogenation. The catalyst was recovered by simple centrifugation and reused for up to five catalytic cycles without alteration in its activity. The present catalyst was found to be viable towards different substrates with excellent activity and TON (18 000 to 28 800). A study on the effect of addenda atom shows that the efficiency of the catalyst can be enhanced greatly by increasing the number of counter protons. This challenging strategy would greatly benefit sustainable development in chemistry as it diminishes the use of organic solvents and offers economic and environmental benefits as water is cheap and non-toxic.

Effect of minor addition on dynamic mechanical relaxation in ZrCu-based metallic glasses

The dynamic mechanical behavior of Zr50-xCu34Ag8Al8Pdx (x = 0 and 2) bulk metallic glasses was probed by mechanical spectroscopy. The results suggest that microalloying retards the relaxation dynamics. The physical aging was analyzed considering a model based on the variation of the concentration of flow units and the Kohlrausch-Williams-Watts (KWW) equation. In the current study, the characteristic parameters of the two models, βc and βaging, reflect the faster annihilation of flow units at higher temperature and the increase of dynamic heterogeneity with temperature, respectively. The mechanical relaxation spectrum was also analyzed. Based on the KWW equation and the quasi-point defect model, replacing Zr with a small amount of Pd can slightly increase the dynamic inhomogeneity and reduce the defect concentration. The analysis according to the HN function suggests that the addition of Pd increases the relaxation time. However, it does not significantly alter the shape of the relaxation time distribution.

Palladium-Coated Single Silver Nanowire Electrodes: Size-Dependent Voltammetry, Enhanced Chemical Stability, and High Performance for Methanol Oxidation.

Silver nanowires (AgNWs) have been extensively studied as promising nanomaterials in optics, next-generation flexible electronics, and energy-related fields, but the stability and the properties at single-nanowire level still need to be investigated carefully. We have successfully prepared single palladium@silver nanowire electrodes (Pd@AgNWEs) by using a laser-assisted pulling method, followed by a galvanic replacement reaction (GRR). The results show that the chemical stability of AgNWs can be improved greatly by coating a small amount of Pd, and the Pd@AgNWEs exhibit superior electrocatalytic performance in methanol oxidation. This work can give us a new insight to investigate the performance of devices/catalysts at the single-particle/nanowire level that will benefit research in flexible electronics and energy-related fields.

Flip Chip Joining with Quaternary Low Melting Temperature Solder Bump Fabricated with Injection Molded Solder

Abstract IBM has developed and has been enhancing the injection molded solder (IMS) technology as an advanced solder bumping technology with flexible solder alloy composition applicable even to fine pitch and small diameter systems. IMS is a simple bumping technology that can form solder bumps by injection of molten solder into via holes patterned in a photoresist layer. IMS is applicable to formation of solder caps for Cu pillar bumping which is a technology widely used for fine pitch applications. One of the advantages of IMS is the capability of using ternary, quaternary, or more compositions solder alloys for bumping, which is not achievable by current plating technology. In this study, the feasibility of IMS bumping and flip chip joining with quaternary solder alloys is demonstrated through assembling of 2.5D package test vehicles using low melting temperature (135°C) SnBi based quaternary alloy solder and associated reliability test. The test vehicles passed the 2250 cycles criteria of thermal cycling test and the observation of microstructures showed that there is no significant crack at the solder joints after flip chip joining or after the 2250 cycles of thermal cycling test. In addition, the tensile test on SnBi based quaternary alloy solder, Sn-58wt%Bi-2.0wt%In with small amount of Pd (less than 1wt%) was conducted using fine diameter specimens. From the SS curve obtained from the test, Young's modulus of the solder was determined as 7.3 GPa and 0.2% proof stress was obtained as 73 MPa both at 25°C. The creep property of the solder was evaluated and the constants for Norton's creep law for the solder were determined at 25, 80 and 110°C. The microstructure observation and Energy Dispersive X-ray (EDX) analysis of the flip chip joints revealed the formation of a thick bismuth (Bi) layer between CuSn intermetallic compound (IMC) layers within a joint. The mechanical simulation of the 2.5D test vehicles showed that the thermomechanical stress of a flip chip joint with Bi/CuSn IMCs at thermal cycling condition is comparable to those of CuSn IMC or Sn-3.0Ag-0.5Cu (SAC305) solder joints consistent with the thermal cycling test result. The advantage of using low temperature quaternary solder materials in flip chip packages is confirmed by mechanical simulation of 2D packages at reflow condition which showed lower stress on low-k dielectric layers for the packages with quaternary solder joints than for the packages with SAC305 solder joints.

The enhanced activity of AuAg/C nanonetwork catalysts for glycerol electrooxidation by small amounts of Pd

The catalytic properties of the Au/C catalyst toward glycerol electrooxidation in alkaline medium have been tremendously improved by an incorporation of Au with Ag. In this work, the catalytic performance of the AuAg/C was further improved by introducing small amount of a third metal, Pd. The catalysts were synthesized by a facile synthesis using the co-reduction of metal precursors in the presence of polyvinyl alcohol. Two series of catalysts with Au:Ag atomic ratios of 1:4 and 1:8 were prepared. Each series consisted of 4 catalysts with various ratios of Au:Pd ranging from 1:0.1 to 1:0.2 and a catalyst without Pd. The resulting metal nanoparticles were formed as nanonetworks with Ag-rich shell. The catalytic activity of the Pd-promoted AuAg-based catalysts was superior over the unpromoted one except for the AuAgxPd0.2/C in which containing too high Pd amount. The most active catalyst was AuAg4Pd0.1/C yielding 2.5 times higher current density than did the AuAg4/C catalyst. Hence, the proposed catalyst model makes use of the surface modifications of the segregated surface, which may influence further catalyst designs for other applications.

Dynamics of Surface Alloys: Rearrangement of Pd/Ag(111) Induced by CO and O2

Alloys of Ag and small amounts of Pd are promising as bifunctional catalysts, potentially combining the inherent selectivity of the noble Ag with that of the more reactive Pd. Stable PdAg surface a...

Recovery of gold(III) from the stripping solution containing palladium(II) by ion exchange and synthesis of gold particles

Separation of macro amount of gold(III) from a small amount of Pd(II) was investigated by ion exchange. From the screening experiments, a nonionic resin Amberlite XAD7HP was selected for this purpose. The adsorption behavior of Au(III) onto Amberlite XAD7HP followed Langmuir isotherm. The loading capacity obtained from the isotherm agreed well with that experimentally measured. Au(III) solution with 99.99% purity was obtained by eluting the loaded Amberlite XAD7HP with the mixture of HCl and acetone. Comparative studies on the synthesis of gold particles were done from the eluate by adding ascorbic acid and K2CO3 in presence and absence of acetone.

Industrial technology for mass production of SnO2 nanoparticles and PbO2 microcube/microcross structures from electronic waste

Waste Printed Circuit Boards (WPCBs) are one of the major recycling challenges in this century with Through-Hole Solder Joint (THSJ) components representing more than 40 wt% of their metallic fraction. THSJs are composed mainly of three metals - Cu, Sn, and Pb; in addition, THSJs can contain a very small amount of Pd and other additives such as Ni, Fe, Al, etc. Recently, dissolution treatment has successfully been used to liberate THSJs as received as well as copper foils, contacts, and tracks. In order to close the lifecycle loop of WPCB metallic fraction, this research has an aim to recover Sn and Pb from the liberated THSJs in the form of SnO2 nanoparticles and PbO2 micro cross/cubic structures as high added-value products using sustainable leaching technique. Nitric Acid was employed to prepare leaching solution, whereas ultrasound treatment was used to precipitate SnO2 and PbO2 precursor from the solution. With time, particles of other metals (Pd, Ni, Fe, Al, etc.) started to precipitate, acting as catalysts (or doping agents) and increasing the precipitation of SnO2 and PbO2. Under the effect of sound waves, temperature, and catalysts, SnO2 and PbO2 precursors transformed into nanoparticles and micro cross/cubic structures; formation and refining degree of these structures was controlled by changing the treatment time. Micro-filtration process was used to separate SnO2 nanoparticles from PbO2 microstructures. Also, copper was recovered from the remaining acidic solution as a Cu(OH)2 by neutralization with NaOH at pH 8. SEM-EDS, TEM, FTIR, XRD, and ICP were used to examine the extracted THSJs, produced nano/micro products and recovered metals. The results showed that the SnO2 and PbO2 had average sizes of 7 nm and 1 μm respectively, while the preparation costs were 6 times lower in comparison to the commercial counterparts. Finally, the authors suggested a layout for applying the developed approach on an industrial scale while referring to the concepts of Circular Economy and Sustainable Development.

Enhanced Chemical Stability of Ag Nanowires by Slight Surface Modification with Pd

AbstractThe chemical stability of Ag nanowires (NWs) can be addressed by introducing a layer of noble metal alloy, in particular Ag–Pd alloy, on the Ag NW surface. Due to the high cost of noble metals, it is practically important to use the least amount of noble metals as possible while achieving the chemical and electrical properties required for the electrode. To minimize the amount of Pd added to Ag NWs, the electrode performance should be correlated with the elemental distribution of Pd in the Ag NW. In this study, the amount of Pd deposited on Ag NWs is varied and the 3D elemental distribution of Pd is characterized using atom probe tomography (APT). The results indicate that chemical stability against oxidation can be achieved when the surface layer contains a very small amount of Pd (≈5 at%), thereby maintaining the good electrical and mechanical properties of the pristine Ag NW electrode. This study demonstrates the suitability of Pd‐treated Ag NWs as electrodes for electro‐chemiluminescence involving corrosive oxidation reactions.

High activity of Pd deposited on Ag/C for allyl alcohol oxidation

The modification of the surface of Ag nanoparticles supported on carbon black (Ag/C) with a small amount of Pd and the electrooxidation of allyl alcohol on the Pd-modified Ag/C (Pd/Ag/C) catalysts are investigated. The Pd/Ag/C catalysts with Pd/Ag atomic ratios of 0.45–1.48:100 are prepared by electrochemically depositing Pd on Ag/C. Structural characterization by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy, and electrochemical analysis reveal low loadings and small surface areas of the deposited Pd. The Pd/Ag/C catalysts are superior to Pd/C in activity for the electrooxidation of allyl alcohol in alkaline solution. When evaluated in terms of the glassy carbon substrate, Pd/Ag/C shows more negative onset and peak potentials and higher peak intensities than Pd/C, although Pd/C has a relatively high activity and the Pd loadings of Pd/Ag/C are much lower than that of Pd/C. When evaluated in terms of the electrochemically active surface area of Pd or the Pd loading mass, Pd/Ag/C has great advantages over Pd/C in activity. For instance, the Pd-mass activity of Pd/Ag/C is up to nearly 200 times that of Pd/C. Low cost is another striking advantage of the Pd/Ag/C catalysts. For ethanol oxidation, on the other hand, the Pd/Ag/C catalysts have no activity, while Pd/C has a relatively high activity.

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.