Support For Pt Catalyst Research Articles

Carbon Materials with Different Dimensions Supported Pt Catalysts for Selective Hydrogenation of 3,4-Dichloronitrobenzene to 3,4-Dichloroaniline

In this study, carbon materials with different dimensions, including the typical one-dimensional (1D) carbon nanotube (CNT), two-dimensional (2D) graphene (GF), and three-dimensional (3D) activated carbon (AC), were investigated as a support for Pt catalysts for the selective hydrogenation of 3,4-dichloronitrobenzene (3,4-DCNB) to 3,4-dichloroaniline (3,4-DCAN). Notably, the Pt/CNT catalyst with the lowest dimension exhibited the best conversion of 3,4-DCNB under mild reaction conditions, followed by Pt/GF. Comprehensive characterizations, including XRD, TEM, XPS, and in situ CO DRIFTS, reveal that the dimension of carbon supports plays an important role in the particle size and electronic properties of Pt species, consequently affecting the catalytic performances of Pt catalysts. According to the results, electron-deficient Pt particles with small sizes are more favorable for the hydrogenation of 3,4-DCNB to 3,4-DCAN. In addition, dynamic tests and in situ DRIFTS of 3,4-DCNB indicated that the carbonaceous supports will largely influence the adsorption and activation capacity of the Pt catalysts, so that Pt loaded on CNT and GF are superior to that on the AC. We believe this study will provide good guidance for designing efficient carbon-supported metal catalysts for selective hydrogenation.

Mechanistic understanding of oxygen spillover enables efficient propane combustion over Pt/AlSOx catalyst

Understanding of the mechanism of saturated alkanes catalytic combustion is crucial for the petrochemical industrial exhaust elimination. Noble metals are commonly proposed to be the active sites for C–H bond activation of saturated alkanes, whereas the critical role of support is largely underestimated. Herein, we reveals a novel pathway for propane activation and combustion on acidic support of Pt catalyst, driven by oxygen spillover, which differs significantly from previously reported reaction mechanisms. Specifically, the Pt/AlSOx-I catalyst was prepared by pyrolyzing the Al2(SO4)3 sol–gel to obtain the acidic micro-mesoporous AlSOx support, followed by loading the Pt active sites using wetness impregnation. In comparison to Pt catalysts supported by Al2O3 nanoparticles (10 nm) or commercially available common γ-Al2O3, the Pt/AlSOx-I catalyst demonstrates superior catalytic activity for propane combustion. It is found that gaseous oxygen species activated on Pt active sites spillovers to acidic support of Pt/AlSOx-I and then drives propane to activation and further oxidation on acidic support, thereby remarkably decreasing the apparent activation energies (Ea) from 112.4 to 72.0 kJ·mol−1. Kinetic results suggest that the negative effect of oxygen competitive adsorption is weakened because propane can be activated on the acidic AlSOx support. Additionally, high proportion of metallic Pt species benefits to gaseous oxygen activation as observed on Pt/AlSOx-R, leading to the further increased catalytic activity with highest specific mass reaction rate of 170.2 μmol gPt−1 s−1 and TOFPt of 0.289 s−1 at 220 °C. Our primary results provide novel insights into revealing the reaction mechanism of saturated alkanes combustion on dual active sites.

Synthesis of a Mesoporous SnO2 Catalyst Support and the Effect of Its Pore Size on the Performance of Polymer Electrolyte Fuel Cells.

The aim of this study was to clarify the effectiveness and challenges of applying mesoporous tin oxide (SnO2)-based supports for Pt catalysts in the cathodes of polymer electrolyte fuel cells (PEFCs) to simultaneously achieve high performance and high durability. Recently, the focus of PEFC application in automobiles has shifted to heavy-duty vehicles (HDVs), which require high durability, high energy-conversion efficiency, and high power density. It has been reported that employing mesoporous carbon supports improves the initial performance by mitigating catalyst poisoning caused by sulfonic acid groups of the ionomer as well as by reducing the oxygen transport resistance through the Pt/ionomer interface. However, carbon materials in the cathode can degrade oxidatively during long-term operation, and more stable materials are desired. In this study, we synthesized connected mesoporous Sb-doped tin oxides (CMSbTOs) with controlled mesopore sizes in the range of 4-11 nm and tested their performance and durability as cathode catalyst supports. The CMSbTO supports exhibited higher fuel cell performance at a pore size of 7.3 nm than the solid-core SnO2-based, solid-core carbon, and mesoporous carbon supports under dry conditions, which can be attributed to the mitigation of the formation of the Pt/ionomer interface and the better proton conductivity within the mesopores even at the low-humidity conditions. In addition, the CMSbTO supports exhibited high durability under oxidative conditions. These results demonstrate the promising applicability of mesoporous tin oxide supports in PEFCs for HDVs. The remaining challenges, including the requirements for improving performance under wet conditions and stability under reductive conditions, are also discussed.

A TiC@TiO2‐C Support for Pt Catalysts to Boost the Oxygen Reduction Reaction

The design of advanced supports to boost the oxygen reduction reaction (ORR) in acidic media is of great significance for proton exchange membrane fuel cells. Herein, TiC@TiO2‐C supports are prepared by the sol–gel method coupled with high‐temperature annealing. The obtained Pt/TiC@TiO2‐C catalyst exhibits outstanding ORR activity such as the half‐wave potential of 0.84 VRHE as well as strong electrochemical stability in 0.1 m HClO4 electrolyte, surpassing the Pt/TiO2‐C and Pt/C catalyst. This result is attributed to the electron transfer from the support to Pt nanoparticles accelerated by the TiC core, which optimizes the electronic structure of Pt to boost the ORR.

(Poster Award - 2nd Place) Enhancement of ORR Activity of Pt Catalyst for PEFCs By Modification with Hydrogen-Bonded Organic Framework Composed of Melamine and Cyanuric Acid

Introduction Improvement in ORR activity of Pt and Pt-based catalysts used in PEFCs for FCEVs is crucial for cost reduction and widespread commercialization [1]. We have reported that surface modification of Pt and Pt-based catalysts with melamine and its derivatives enhance ORR activity [2, 3]. However, it is concerned that melamine is easily washed out by water generated at the cathode in PEFCs because melamine is soluble in water (3.1 g/L). In this study, a hydrogen-bonded organic framework (HOF) composed of melamine (MEL) and cyanuric acid (CA) [4] was prepared to suppress the washing-out problem and investigated as a modifier of Pt catalyst loaded on mesoporous carbon (MPC) support. Experimental MPC (CNovel MH-18, SBET 1,334 m2/g, TOYO TANSO) was used as a carbon support for Pt catalyst. Pt/MPC (50 wt%) was prepared by an impregnation-thermal decomposition method using Pt(NO2)2(NH3)2 as a Pt source. Pt/MPC was modified as the following procedure. First MEL was impregnated within the Pt/MPC by ultrasonically dispersing 100 mg Pt/MPC catalyst and 10 mg MEL (10 wt.% to the catalyst) in 100 mL pure water, followed by drying using a rotary evaporator (MEL-Pt/MPC). Then MEL-Pt/MPC (110 mg) was dispersed in 100 mL water containing 10 mg CA and dried to obtain HOF-Pt/MPC. The catalyst was loaded on a glassy carbon (GC) RDE. CV of the catalyst was recorded in Ar-saturated 0.1 M HClO4 at 25oC at a scan rate of 50 mV/s and ORR activity was evaluated by LSV performed at 25oC in O2-saturated 0.1 M HClO4 at a scan rate of 10 mV/s on the positive sweep while rotating the GC disk electrode at 1,600 rpm. To investigate the stability of MEL and HOF on the electrode, the GC electrode after the initial measurements was immersed in 0.1 M HClO4 at 80oC for 1 h, followed by washing with pure water, and CV and LSV were measured in the same manner at 25oC. Results and Discussion Figure 1 shows the molecular structure of MEL-CA HOF [4]. Figures 2 and 3 show CVs and LSVs, respectively, for bare, MEL-, and HOF-Pt/MPC before the stability tests. For bare Pt/MPC in Fig. 2, peaks were observed around 0.05−0.4 V and 0.6−1.0 V, which are assigned to the adsorption/desorption of underpotential deposited hydrogen (Hupd) and Pt-oxide species formation/reduction, respectively. For MEL- and HOF-Pt/MPC, the HUPD peak area decreased slightly, while the onset potential for Pt-oxide formation was shifted positively in Fig. 2. As a result, ORR activity of MEL- and HOF-Pt/MPC was improved remarkably as shown in Fig. 3 (mass activity: 894 and 829 A/g, respectively, at 0.9 V). These results indicate that HOF has an enhancement effect for ORR activity similar to that of MEL modification. Figure 4 shows CVs for bare, MEL-, and HOF-Pt/MPC after the stability tests at 80oC for 1 h. In Fig. 4, the waves of Hupd and Pt-oxide of MEL-Pt/MPC became similar to those of bare Pt/MPC after the stability test, which indicated that MEL was washed out in the electrolyte solution. On the contrary, the HOF-Pt/MPC catalyst substantially retained the waves shapes before the stability test shown in Fig. 2. These results indicate that the HOF has higher stability against washing-out than MEL owing to a much lower solubility at 80°C. Figure 5 shows LSVs after the stability tests. The loss of activity of HOF-Pt/MPC (639 A/g) was smaller than MEL-Pt/MPC (553 A/g) owing to the suppression of washing-out, which is consistent with the results in Fig. 4. The results of single cell tests using bare Pt/MPC, MEL-Pt/MPC and HOF-Pt/MPC cathode catalysts will be presented at the meeting.This study was partly supported by NEDO, Japan.

Improved DMFC water management via superwetting, high-performance catalyst synthesized by nanocapsule method

In this paper, an effective water management structure for direct methanol fuel cell (DMFC) is designed based on the super-hydrophilicity of nitrogen-doped carbon aerogel which functions as the support of Pt catalyst. Considering the case where Pt nanoparticles deposited into the nanopores of the support are difficult to contact with the ionomer, the catalyst is synthesized by nanocapsule method, and the experimental results prove that a favorable improved oxygen reduction reaction activity of the prepared catalyst has been achieved. The produced hydrophilic catalyst is used to construct a two-layered cathode catalyst layer (CCL) with hydrophilic inner layer and hydrophobic outer layer as water management structure, since a single-layered hydrophilic CCL shows poor performance due to serious water flooding. A mathematical model is developed to study the influence of two-layered CCL, and its effect on cell performance is also analyzed by polarization tests. For the improved liquid-feed DMFCs, high hydraulic pressure is formed in CCL to promote water recovery and inhibit methanol crossover. For the improved vapor-feed DMFC, the enhanced water recovery secures the water required for the anodic oxidation reaction, which increases the output performance and stability greatly. This study provides a new method for the optimization of DMFC.

Phosphorus-doped activated carbon as a platinum-based catalyst support for electrocatalytic hydrogen evolution reaction

Carbon is an excellent support that may influence the electronic structure of metal particles. However, carbon lacks functional groups on its surface, making it unsuitable for carrying catalysts, resulting in metal agglomeration. This can be solved by heteroatom doping to effectively optimize ligand structure and electronic characteristics of carbon materials, as well as enhance the intrinsic activity and steadiness of Pt/C catalysts. Herein, phosphorus-doped activated carbon (P-AC) was prepared as support for Pt catalysts to enhance the hydrogen evolution reaction (HER) under alkaline conditions. The main doped form of P-AC by potassium dihydrogen phosphate was identified as C3-PO, considered the most stable phosphorus-oxygen functional group in the carbon lattice with a key role in the HER process. The existence of C3-PO enhanced the interaction between P-AC and Pt nanoparticles, thereby tuning the electronic state of Pt and further optimising the adsorption of H* on Pt. Consequently, the resulting Pt/P-AC catalysts exhibited excellent HER activity (Tafel slope: 33.0 mV·dec−1, overpotential: 36.1 mV), with 4.6-fold incremented mass activity (1.220 A·mgpt−1) at a voltage of 70 mV than commercial catalysts containing 40 wt% Pt/C (0.266 A·mgpt−1). Moreover, a remarkable electrochemically active surface area (ECSA) of 66.95 m2·gPt−1 was observed in the Pt/P-AC catalysts. The Pt/P-AC catalysts also displayed high stability with better activity loss than commercial 40% Pt/C after 10,000 cycles. In sum, the proposed method looks promising for future syntheses of novel HER catalysts with high HER performance under alkaline conditions.

Highly efficient and durable Y(OH)3/rGO/Pt ternary hybrid electro-catalyst for the methanol oxidation reaction

Tailoring highly durable and active anode catalysts is currently the primary concern to the commercial viability of direct methanol fuel cells (DMFC). Herein, we report a ternary hybrid electro-catalyst, Y(OH)3/rGO/Pt, with excellent MOR activity and durability compared to commercial Pt/C for the first time. Y(OH)3 on reduced graphene oxide is chosen as the catalyst support for Pt to improve its electrocatalytic activity and tolerance towards the carbonaceous intermediates formed during MOR. Pt, along with Y(OH)3/rGO support, exhibits a mass activity of 230 mA/mg with an onset potential of 0.58 V (vs. RHE), which is 4.5 times greater than that of commercial Pt/C (51.55 mA/mg, 0.69 V). If/Ib ratio and the electrochemical active surface area are increased on employing Y(OH)3/rGO as catalyst support to Pt. The enhanced catalytic activity is attributed to the synergistic effect between highly conductive rGO matrix, intermediate poisoning tolerant Y(OH)3, and Pt catalyst. A significant decrease in MOR activity was observed after calcining the Y(OH)3/rGO/Pt catalyst due to the reduction in surface Y-OH groups.

Application of silica-alumina as hydrothermally stable supports for Pt catalysts for acid-assisted soot oxidation

Application of silica-alumina as hydrothermally stable supports for Pt catalysts for acid-assisted soot oxidation

Hydrothermal acid etching of alumina beads and its effect on isobutane dehydrogenation performance over Pt/γ-Al2O3 catalyst

Millimeter-scale spherical alumina used as the support of Pt catalyst for isobutane dehydrogenation was prepared by alginate assisted sol-gel method, and then hydrothermal treated in 0.5 M HNO3 to improve its porous structure and surface properties. The effects of acid etching time on the composition, structure, surface acidity, redox property, catalytic dehydrogenation performance and carbon deposition of catalyst were investigated by ICP-OES, SEM, TEM, XRD, N2 adsorption-desorption, 27Al MAS NMR spectra, NH3-TPD, H2-TPR, isobutene transient response experiment and TGA. The results show that the acid treatment can effectively remove zinc species and partial aluminum from the surface of alumina beads, which can create defect sites and increase the specific surface area of alumina, thus improving the dispersion of Pt particles. In addition, acid etching significantly increases the acidity of alumina and enhances the interaction between Pt particles and alumina through the formation of defect sites. The Pt/Al2O3-NA-3 possesses the smallest size of Pt particles, the strongest Pt-alumina interaction, maximum number of acid sites and the highest isobutene yield of 33% even after 270 min reaction.

Enhanced Ageing Performance of Sulfonic Acid-Grafted Pt/C Catalysts.

Chemical functionalization of carbon support for Pt catalysts is a promising way to enhance the performance of catalysts. In this study, Pt/C catalysts grafted with various amounts of phenylsulfonic acid groups were prepared under mild conditions. The influence of sulfonic acid groups on the physiochemical characteristics and electrochemical activities of the modified catalysts were studied using X-ray diffraction, X-ray photoelectron spectroscopy, a transmission electron microscope, and cyclic voltammetry (CV). The presence of the chemical groups enhanced the hydrogen adsorption onto/desorption off the Pt surface during the CV cycling. In contrast, the hydrogen peaks of the grafted catalysts increased after 500 CV cycles, especially for Pt (111) facets. The highest electrochemical surface area (ECSA) after the aging test was obtained for the catalyst with 18.0 wt.% graft, which was ca. 87.3% higher than that of the non-functionalized Pt catalyst. In the density functional theory (DFT) calculation, it was proven that SO3H adsorption on the crystalline was beneficial for Pt stability. The adsorption energy and bond distance of the adsorbed SO3H on Pt (110), (100), and (111) surfaces were calculated. All the stable configurations were obtained when O from S-O single bond or S was bound to the Pt surface, with the adsorption energy following the trend of (111)F > (100)H > (110)H. This result was consistent with the ECSA experiment, which explained the high electrochemical stability of the sulfonic acid groups-grafted Pt/C catalyst.

Catalytic performance of metal-organic framework (MOF) and micro-mesoporous composites as the supports for Pt catalysts for n-heptane isomerization

Catalytic performance of metal-organic framework (MOF) and micro-mesoporous composites as the supports for Pt catalysts for n-heptane isomerization

Fabrication and Performance Evaluation of Tubular Catalyst Layer for Proton Exchange Membrane Fuel Cell

Over the past several decades, planar proton exchange membrane fuel cells (PEMFCs) received considerable attention due to their simple structure, manufacturing, and easy integration. However, current PEMFC electrode designs are disadvantaged by high cost, insufficient mass transport, nonuniform reactant, current and temperature distribution, and limited water removal. The development of a novel tubular fuel cell design could address these challenges. Tubular-shaped PEMFC offers several advantages over planar one, including lower pressure drop, efficient water removal, reduced mass transport losses, and cost reduction owing to removing one of gas diffusion layer/bipolar plate (GDL/BPP) side.This work developed a carbon nanofiber (CNF)/Pt-based cathode for a tubular fuel cell. The tubular CNF support for Pt catalyst was fabricated employing the electrospinning method. Polyacrylonitrile (PAN) was used as the precursor. The electroless deposition of Pt using the chloroplatinic acid solutions was applied to produce well-dispersed low Pt loading nanowires. The tubular CNF/Pt electrodes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), ex-situ cyclic voltammetry to determine the CF and Pt morphology and feasibility of the prepared layer in PEMFC application. SEM images indicated that increasing the Pt precursor concentration in the plating bath leads to higher Pt loading and larger Pt clusters on the CNF surface. The calculated electrochemical active surface area (ECSA) trend imparts that high Pt loading is less favorable as thick Pt layers lead to low Pt utilization and increased material costs. ECSA results agreed with SEM images, suggesting that the medium Pt concentration (1.5 g L-1 Pt precursor) developed a homogenous Pt distribution and comparable Pt surface area of 24 m2 gPt -1 for the Pt loading of 0.046 mg cm-2, proving the feasibility of the proposed process.

Influence of Cathode Catalyst Layer with SiO2-Coated Pt/Ketjen Black Catalysts on Performance for Polymer Electrolyte Fuel Cells

In this study, we investigated the effect of silica (SiO2) layer included in a cathode catalyst layer (CL) on the performance for polymer electrolyte fuel cells (PEFCs). Porous carbons such as Ketjen black (KB) have been widely used as a support for Pt catalysts in PEFCs. Such KB-supported Pt catalyst (Pt/KB) was used as a cathode CL with low ionomer content (a condition of low proton conductivity). The Pt/KB was then coated with SiO2. In addition, the Pt/KB and SiO2-coated Pt/KB (SiO2-Pt/KB) were measured and analyzed under relative humidity (RH) conditions (100% and 20%). The catalyst ink of SiO2-Pt/KB showed higher stability and dispersion compared to Pt/KB, due to the hydrophilic surface characteristics of SiO2, which act as a binder-like ionomer. The performance of the SiO2-Pt/KB at 100% RH, was significantly lower than that of Pt/KB, whereas the performance of the Pt/KB at 20% RH, was significantly improved by SiO2 coating. This is due to an increase in the proton conductivity, which can be attributed to the hydrophilic properties of SiO2. Based on these results, the effect of SiO2 coating on performance, depending on carbon supports of SiO2-coated Pt/Carbon catalysts, could be evaluated.

The effects of alumina morphology and Pt electron property on reversible hydrogenation and dehydrogenation of dibenzyltoluene as a liquid organic hydrogen carrier

The morphologies and the electron property of catalysts play the very important roles in the hydrogenation and dehydrogenation of liquid organic hydrogen carriers (LOHCs) such as dibenzyltoluene (DBT). The different morphologies and pore structures of γ-Al2O3 and MoxC doped γ-Al2O3 were synthesized as the supports for Pt catalysts. After analyzing of various characterizations and catalytic testing, it was found that the large surface area and the mesoporous structure of catalysts are beneficial to both DBT hydrogenation and perhydro-dibenzyltoluene (H18-DBT) dehydrogenation. The doping of MoxC promoted the formation of the smaller Pt nanoparticles and increased Pt dispersion. The forming Pt–Mo structure is beneficial to hydrogen spillover which suppress the formation of by-product. The high Pt dispersion of 0.1 wt% MoxC doped Pt/Al2O3 catalyst plays the positive roles in increasing H18-DBT dehydrogenation activity.

Magnetically separable and efficient platinum catalyst: Amino ligand enhanced loading and Fe2+ facilitated Pt0 formation

AbstractUnderstanding the interaction between metal and the support is crucial in searching of efficient and recyclable noble metal heterogeneous catalysts. Herein, we report a core‐shell structured support for Pt catalyst with a magnetic Fe3O4 core and a porous silica shell bearing amino groups. The prepared catalyst Fe3O4@mSiO2‐APTES‐Pt showed a high loading of Pt (7.93 wt%) as well as a high fraction of active Pt0 species, which both contributed to the high activity toward a model hydrosilylation reaction between 1‐octene and 1, 1, 1, 3, 5, 5, 5‐heptamethyltrisiloxane (HMTS). X‐ray photoelectron spectra (XPS) analysis revealed that the amino ligands played a dominant role in Pt loading and Fe2+ probably facilitated the formation of low valence Pt0. Under the combined effect of magnetic nature of the support and proper support‐metal interactions, the catalyst exhibited excellent recyclability with a recovery of 99.7% and a yield of over 90% even after eight runs of recycling. This catalyst may provide a new option in designing and preparing heterogeneous catalysts that are highly recoverable, reusable, and recyclable.

Microfabrication atomic layer deposited Pt NPs/TiN thin film on silicon as a nanostructure signal Transducer: Electrochemical characterization toward neurotransmitter sensing

Titanium nitride (TiN) is widely utilized in microelectrode array fabrication for electrophysiological recordings due to its relatively low noise levels, long term stability, and exceptional biocompatibility. Atomic layer deposition (ALD) is a well-established approach for the fabrication of TiN thin films, offering great control over the thickness and properties of the films. Although, advanced procedures have been reported to develop micro and nanostructured electrodes, TiN thin film has yet not been widely applied as electrode material for electrochemical sensing, and characterization of these ALD fabricated TiN films is lacking. Here, we study the use of TiN thin films as electrochemical signal transducer for neurotransmitter dopamine (DA) detection with emphasis on investigation the effect of oxygen functionalities on the electrochemical performance of the films. We find that in order to have high enough sensitivity and selectivity the electrode material used to realize the measurements must be modified. In this work, we described TiN thin film surface modification through hybridization of microfabrication and nanocomposite approaches. Because of its good adhesion, TiN is considered as a high interesting support for Pt catalyst. Therefore, ALD was used to deposit TiN thin films and to design Pt nanoparticles (Pt NPs) on highly conductive boron-doped silicon. Further modification was done through multiwalled carbon nanotubes (MWCNTs), which were immobilized on Pt NPs/ TiN hybrid electrode by Nafion film. Synergistic effect of Pt NPs, MWCNTs, and Nafion film caused significant increase in the electrocatalytic activity towards DA electrooxidation. The proposed sensor material was characterized by focused ion beam milling combined with scanning electron microscopy (FIB-SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), spectroscopic ellipsometry, contact angle measurement and its electrochemical behavior was studied by cyclic voltammetry (CV). CV technique was applied for sensing DA in the range of 0.05–35 µM (R2 = 0.990) with a good sensitivity (16.31 μA/μM) and a low detection limit of 40 nM (for S/N = 3). The developed sensor exhibited reasonable response time and good stability.

Enhanced PEMFC durability with graphitized carbon black cathode catalyst supports under accelerated stress testing.

The anti-corrosion properties of the carbon substrates of cathode catalysts play a vital role in the commercialization of fuel cell vehicles. Our report reveals the enhanced durability of graphitized carbon black catalyst substrates in polymer electrolyte membrane fuel cells (PEMFCs), tested under simulated start-stop cycling and high potential holding conditions. Graphitized carbon treated at various temperatures is used as the support for Pt catalysts. The catalyst utilizing graphitized carbon treated at 1800 °C demonstrates superior antioxidation properties and the inhibition of Pt particle coarsening. The decay ratio of the potential at 1000 mA cm−2 has been reduced from 34.9% (commercial Pt/C) to 0.5% during high potential holding accelerated stress testing. Correspondingly, the growth of Pt particles is reduced from 0.95 nm (commercial Pt/C) to 0.08 nm; that is, the coalescence of Pt particles is effectively alleviated upon using graphitized carbon black.

MOF-derived Co embedded into N-doped nanotube decorated mesoporous carbon as a robust support of Pt catalyst for methanol electrooxidation

The fabrication of a Pt-based catalyst with high activity and stability for methanol electrooxidation is both of vital importance and challenging for direct methanol fuel cells. Herein, a catalyst support based on Co embedded into N-doped nanotube decorated mesoporous carbon (Co@NCNTs-MC) derived from metal-organic frameworks (MOFs) was synthesized by a pyrolysis method at an appropriate temperature and duration using ZIF-67 as a precursor, and melamine as an additional nitrogen source. The presence of melamine ensures adequate nitrogen content at high temperature, promotes the formation of NCNTs through the help of Co nanoparticles in the pyrolysis process and forms a mesoporous carbon structure. The optimum pyrolysis condition was found to be 800 °C for 4 h. A Pt-based catalyst was synthesized with the as-prepared Co@NCNTs-MC support which was found to significantly improve the dispersion of Pt nanoparticles and enhance the transportation of electrons and mass. Co-Nx bonds are shown to provide an abundance of active sites. A Pt/Co@NCNTs-MC800-4 sample is found to show mass activities of 700.3 mA mg−1Pt for methanol electrooxidation, which is approximately 4.5 times higher than that of 20% Pt/C. This work brings new opportunities to design and prepare promising catalyst supports for direct methanol fuel cells.

Effect of zeolite amount on the properties of Pt/(AlSBA-15 + Beta zeolite) micro-mesoporous catalysts for the hydroisomerization of n-heptane

The composite (AlSBA-15 + Beta zeolite) materials were prepared using a simple one-step hydrothermal synthesis, aiming to investigate the effect of the ratio AlSBA-15 : zeolite on their physicochemical properties. The resulting micro-mesoporous materials (SBB) containing from 14 to 25 wt% of zeolite were used as supports for Pt catalysts in hydroisomerization of n- heptane (n-C7). Obtained catalysts were characterized by means of nitrogen sorption, XRD, Py–IR, 27Al MAS NMR, CO chemisorption, TEM and SEM. It was found, that the textural properties of the micro-mesoporous materials were comparable to pure AlSBA-15. It also appeared that the introduction of zeolite into AlSBA-15 at the synthesis stage affected the total acidity of the composite materials. Both the total acidity and strength of acid sites depended on AlSBA-15: zeolite ratio. The results of n-C7 hydroconversion showed that catalysts containing 14 and 25 wt% of zeolite provided the highest yield of the most desired, high-octane number products. The most promising Pt/AlSBA-15 + BEA catalysts (i.e. containing 14 and 25 wt% of Beta) allows to improve research octane number from 0 to the 65–70 points.