Degree Of Pt Research Articles

Bimetallic and trimetallic Pt-based catalysts for selective hydrogenation of p-chloronitrobenzene to p-chloroaniline

The selective hydrogenation of p-chloronitrobenzene (p-CNB) is a crucial step in the preparation of p-chloroaniline (p-CAN). However, the competitive reactions of NO2 hydrogenation and C-Cl hydrogenolysis make it challenging to inhibit the undesired dechlorination side reaction during this process. Herein, we developed a series of bimetallic PtM/γ-Al2O3 (M = Co, Cu, Ni, Fe, Zn, Ga, and Sn) and trimetallic PtCuCox/γ-Al2O3 catalysts to enhance the selectivity of p-CAN and suppress the formation of aniline (AN). Among the bimetallic catalysts, PtCo/γ-Al2O3 showed the highest hydrogenation activity due to its high electron-rich degree of Pt. Conversely, PtCu/γ-Al2O3 displayed the highest p-CAN selectivity and the lowest AN selectivity, primarily owing to the presence of electron-deficient Pt. Remarkably, the trimetallic PtCuCo/γ-Al2O3 catalyst exhibited superior hydrogenation performance, achieving 97.3 % p-CAN selectivity and 0.4 % AN selectivity at complete conversion of p-CNB, while maintaining good stability over five cycles. This enhancement was attributed to the synergistic effect among Pt, Cu and Co. To further investigate the effect of support, we prepared bimetallic PtM3 (M = Co, Cu, Ni and Zn) catalysts supported on reducible CeO2. Interestingly, the use of CeO2 as a support facilitated the condensation path from p-CNB to p-CAN via azobenzene compounds, distinct from the direct path observed with γ-Al2O3 support. Furthermore, the AN selectivity on all PtM3/CeO2 was less than 1 %, indicating effective inhibition of dechlorination reactions. This study highlights the importance of a multi-metal synergistic strategy and the effect of the support to achieve superior performance in chloronitrobenzene hydrogenation.

Dendritic Mesoporous Silica Nanoparticle Supported PtSn Catalysts for Propane Dehydrogenation.

PtSn catalysts were synthesized by incipient-wetness impregnation using a dendritic mesoporous silica nanoparticle support. The catalysts were characterized by XRD, N2 adsorption-desorption, TEM, XPS and Raman, and their catalytic performance for propane dehydrogenation was tested. The influences of Pt/Sn ratios were investigated. Changing the Pt/Sn ratios influences the interaction between Pt and Sn. The catalyst with a Pt/Sn ratio of 1:2 possesses the highest interaction between Pt and Sn. The best catalytic performance was obtained for the Pt1Sn2/DMSN catalyst with an initial propane conversion of 34.9%. The good catalytic performance of this catalyst is ascribed to the small nanoparticle size of PtSn and the favorable chemical state and dispersion degree of Pt and Sn species.

Integrated CoPt electrocatalyst combined with upgrading anodic reaction to boost hydrogen evolution reaction

Exploiting highly effective and low-cost electrocatalyst for water splitting is an instant challenge for the development of sustainable hydrogen energy. In this work, we report an integrated bifunctional electrocatalyst composed of CoPt nanoparticles uniformly distributed on the carbon nanosheet array (CNs@CoPt), which exhibits excellent activity for both cathodic hydrogen evolution in a wide range of pH conditions and anodic glycerol oxidation reaction. Based on this novel electrocatalyst, a hydrogen evolution coupled with glycerol oxidation system was constructed, exhibiting dramatically enhanced hydrogen production rate (48 L h−1 m−2) in cathode, larger than traditional water splitting system (27 L h−1 m−2), and gaining high-valuable product (formate, 113 g h−1 m−2) in anode. Moreover, a quite high utilization degree of Pt (35.1%) is achieved on CNs@CoPt owing to this hierarchical and alloy structure, 3.3 times higher than that of commercial Pt/C (10.6 %). We believe that the strategy demonstrated in this work can be extended to fabricate other multifunctional integrated electrocatalysts with high performance for hydrogen production.

Surface and chemical characteristics of platinum modified activated carbon electrodes and their electrochemical performance.

Platinum (Pt) loaded activated carbons (ACs) were synthesized by the thermal decomposition of platinum (II) acetylacetonate (Pt(acac)2) over chemically activated glucose-based biochar. The effect of Pt loading on surface area, pore characteristics, surface chemistry, chemical structure, and surface morphology were determined by various techniques. XPS studies proved the presence of metallic Pt0 on the AC surface. The graphitization degree of Pt loaded ACs were increased with the loaded Pt0 amount. The electrochemical performance of the Pt-loaded ACs (Pt@AC) was determined not only by the conventional three-electrode system but also by packaged supercapacitors in CR2032 casings. The capacitive performance of Pt@AC electrodes was investigated via cyclic voltammetry (CV), galvanostatic charge-discharge curves (GCD), and impedance spectroscopy (EIS). It was found that the Pt loading increased the specific capacitance from 51 F/g to 100 F/g. The ESR drop of the packaged cell decreased with the Pt loading due to the fast flow of charge through the conductive pathways. The results showed that the surface chemistry is more dominant than the surface area for determining the capacitive performance of Pt loaded AC-based packaged supercapacitors.

Structural, electronic, and electrochemical analyses of sputter-coated Pt and Pt–Co/GCE electrodes with ultra-low metal loadings for PEM fuel cell applications

In this study, unsupported platinum and platinum–cobalt ultra-thin catalyst layers with varying metal loadings were prepared by a sequential magnetron sputtering technique. The deposited catalyst layers were characterized using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), X-ray diffraction, cyclic voltammetry, and rotating disk electrode methods. Ultra-low Pt loadings, in the range of 6–22 µg cm−2, were used to examine the kinetic properties of the deposited catalyst layers. The results revealed that the highest electrochemically active surface area, 89.7 m2 g−1, was obtained for Pt:Co (1:3) nanocatalyst with an optimum Pt loading of 10 µg cm−2. The XPS and UPS results indicated that the catalyst layers prepared at elevated temperatures contained a high degree of Pt–Co interaction. It was seen that the incorporation of Co atoms into the Pt lattice improved the oxygen reduction reaction (ORR) activity of the catalysts at certain Pt:Co concentrations and sputtering temperatures. Among all catalyst layers, the highest mass and specific current density values (793.08 A $${\text{g}}_{\text{Pt}}^{ - 1}$$ and 1163.18 µA cm−2, respectively) were obtained from the electrode with 10 µg cm−2 Pt loading prepared at 300 °C. Although the introduction of Co atoms in the catalyst layer did not result in a systematic enhancement in the ORR performance, the Pt:Co (1:1) composition deposited at 300 °C had the highest ORR performance with a mass activity of 571.17 A $${\text{g}}_{\text{Pt}}^{ - 1}$$ and a specific activity of 835.59 µA cm−2 among the all Co-containing catalysts. Our results indicated that heat treatment, surface structure, and composition have profound effects on the performance of the catalyst layers.

Influence of thermal treatment atmosphere on photogenerated charge separation of Pt/N–TiO2/SrTiO3 for efficient hydrogen evolution

Solar light-responsive platinized N-doped TiO2/SrTiO3 that was thermally treated under H2 atmosphere (H–0.2Pt/N–TiO2/SrTiO3) exhibited high activity for hydrogen evolution under simulated sunlight irradiation. The hydrogen evolution rate of H–0.2Pt/N–TiO2/SrTiO3 was 2740 μmol/h/g, which was approximately 88 times higher than that of N–TiO2/SrTiO3. Results of X-ray photoelectron microscopy demonstrated that the thermal treatment atmosphere was the main factor that contributed to Pt(0) formation, and the proportion of Pt(0) increased in the following order of air < N2 < H2. Moreover, photoluminescence analysis showed that photogenerated charge separation efficiency was positively correlated with the degree of Pt(0) formation, as evidenced by the better photogenerated electron acceptance of Pt(0). The influences of Pt coating amount and photocatalyst concentration on hydrogen evolution efficiency were also investigated. The highest hydrogen evolution efficiency was attained when the Pt coating amount was 0.2 wt% and the photocatalyst concentration was controlled at 2.0 g/L. The stability and reusability experiments for hydrogen evolution and material characterization showed that the H–0.2Pt/N–TiO2/SrTiO3 with high physicochemical stability is a promising candidate material for practical application.

Unravelling the Formation of Pt–Ga Alloyed Nanoparticles on Calcined Ga-Modified Hydrotalcites by in Situ XAS

The chemical transformations taking place during the formation of catalytic Pt–Ga alloyed nanoparticles supported on calcined Ga-modified hydrotalcite Mg(Ga)(Al)Ox are investigated. The starting point is a Pt(acac)2 precursor impregnated onto a Mg(Ga)(Al)Ox support. An oxidative treatment first yields Pt nanoparticles, while subsequent reduction efficiently delivers Ga from the support framework to Pt, forming Pt–Ga alloyed clusters. Different steps are discerned in this process based on in situ XAS analysis. During oxidative heating to 350 °C, the initially adsorbed Pt(acac)2 precursor molecules decompose and form atomically dispersed Pt4+ species with 5-/6-fold oxygen coordination. A fraction of the formed Pt–O bonds consists of strong anchoring points between Pt4+ species and support oxygen, decreasing the Pt mobility induced by the basic support. Further calcination to 650 °C leads to scission of these Pt–O support bonds, allowing more mobile Pt species to form 3–11 atom Pt fcc nanoparticles with an oxidized external surface. These subnanometer clusters are proposed to be bound to the Mg(Ga)(Al)Ox support by extended 2.5 Å Pt0–(OH)− induced dipole-ion interfacial bonds. Cooling down and subsequent heating in H2 up to 450 °C causes sintering and reduction of these nanoparticles. In the course of this reduction, the proposed 2.5 Å Pt0–(OH)− interfacial bonds are replaced by common 2.0 Å Pt–O bonds. Further heating in H2 to 650 °C causes reduction of framework Ga, allowing Ga transport from the support to the Pt clusters to form 1.5 nm Pt–Ga alloyed nanoparticles. This activated Pt–Ga/Mg(Ga)(Al)Ox catalyst is subjected to one O2/H2 redox cycle at 650 °C to mimick the catalyst regeneration procedure. The redox cycle induces an alloy restructuring, leading to a decrease in the degree of Pt–Ga alloying. Wavelet transformed XAS—complemented by XANES and EXAFS—is shown to be a key tool to disclose the mechanistic details occurring during Pt–Ga formation.

Linear polystyrene-stabilized Pt nanoparticles for aerobic alcohol oxidation and hydrogen-transfer reduction in aqueous media

Linear polystyrene-stabilized Pt nanoparticles were prepared using phenylboronic acid and NaBH4 as the reductant. The size of Pt nanoparticles was dependent on the reductant, while the immobilization degree of Pt was not. The resultant polystyrene-stabilized Pt nanoparticles showed high catalytic activity for aerobic alcohol oxidation in water and hydrogen-transfer reduction of olefin, ketone, and nitro group using 2-propanol as a hydrogen donor. The catalyst was recycled without significant loss of activity.

Preparation of Pt–Co nanocatalysts on carbon nanotube electrodes for direct methanol fuel cells

The electrochemical activities of three types of Pt–Co/CNT catalysts, prepared from different Co depositions, in methanol oxidation have been investigated. X-ray diffraction reveals that these Pt–Co/CNT catalysts possess not only different crystalline sizes but also different levels of atomic distribution. The use of strong reducing agent (NaBH 4) enables the formation of a cobalt layer over the Pt surface, inducing bimetallic Pt–Co particles, whereas direct thermal reduction enables the formation of Pt–Co nanoalloy with a high degree of alloying. It has been shown that the normalized active surface coverage increases the alloying degree of Pt–Co catalysts, indicating the importance of atomic distribution. Cyclic voltammetric measurement also reveals that the Pt–Co/CNT catalyst with a good alloying degree exhibits a better electrochemical activity, high CO tolerance, and long-term durability (> 100 cycles).

Preparation of supported Pt–Co alloy nanoparticle catalysts for the oxygen reduction reaction by coverage with silica

Pt-based alloy catalysts such as carbon black-supported Pt–Co catalysts (Pt–Co/CB) are used in the oxygen reduction reaction in polymer-electrolyte fuel cells (PEFCs) and are generally treated at high temperatures to allow for alloy formation. However, treatment of these catalysts at high temperatures results in serious aggregation of alloy particles. In this study, a Pt–Co/CB catalyst was covered with silica layers to inhibit the aggregation of alloy particles during treatment of the catalyst at high temperature for alloy formation. Coverage of Pt–Co/CB with silica promoted Pt–Co alloy formation with a high alloying degree and a small particle size, whereas the alloying degree of Pt–Co alloys in Pt–Co/CB without silica-coating was low, and these alloy particles were seriously aggregated during treatment at high temperature. These silica-coated Pt–Co/CB catalysts showed high activity and excellent durability for the oxygen reduction reaction.

Single-step polyol synthesis of alloy Pt7Sn3 versus bi-phase Pt/SnOx nano-catalysts of controlled size for ethanol electro-oxidation

Disordered alloy and bi-phase PtSn nanoparticles of nominal Pt:Sn ratio of 70:30 atomic % with controlled size and narrow size distribution were synthesized using a single-step polyol method. By adjusting the solution pH it was possible to obtain Pt7Sn3 nanoparticles of various sizes from 2.8 to 6.5 nm. We found that the presence of NaOH in the synthesis solution not only influenced the nanoparticle size, but as it was revealed by XRD, it apparently also dictated the degree of Pt and Sn alloying. Three catalysts prepared at lower NaOH concentrations (CNaOH < 0.15 M) showed disordered alloy structure of the nominal composition, while the other three catalysts synthesized at higher NaOH concentrations (CNaOH > 0.15 M) consisted of bi-phase nanoparticles comprising a crystalline phase close to that of pure Pt together with an amorphous Sn phase. These observations are plausibly due to the phase separation and formation of monometallic Pt and amorphous SnOx phases. A proposed reaction mechanism of Pt7Sn3 nanoparticle formation is presented to explain these observations along with the catalytic activities measured for the six synthesized carbon-supported Pt7Sn3 catalysts. The highest catalytic activity towards ethanol electro-oxidation was found for the carbon-supported bi-phase catalyst that formed the largest Pt (6.5 nm) nanoparticles and SnOx phase. The second best catalyst was a disordered alloy Pt7Sn3 catalyst with the second largest nanoparticle size (5 nm), while catalysts of smaller size (4.5–4.6 nm) but different structure (disordered alloy vs. bi-phase) showed similar catalytic performance inferior to that of the 5 nm disordered alloy Pt7Sn3 catalyst. This work demonstrated the importance of producing bi-metallic PtSn catalysts with large Pt surfaces in order to efficiently electro-oxidize ethanol.

Particle size dependence of CO tolerance of anode PtRu catalysts for polymer electrolyte fuel cells

An anode catalyst for a polymer electrolyte fuel cell must be CO-tolerant, that is, it must have the function of hydrogen oxidation in the presence of CO, because hydrogen fuel gas generated by the steam reforming process of natural gas contains a small amount of CO. In the present study, PtRu/C catalysts were prepared with control of the degree of Pt–Ru alloying and the size of PtRu particles. This control has become possible by a new method of heat treatment at the final step in the preparation of catalysts. The CO tolerances of PtRu/C catalysts with the same degree of Pt–Ru alloying and with different average sizes of PtRu particles were thus compared. Polarization curves were obtained with pure H 2 and CO/H 2 (CO concentrations of 500–2040 ppm). It was found that the CO tolerance of highly dispersed PtRu/C (high dispersion (HD)) with small PtRu particles was much higher than that of poorly dispersed PtRu/C (low dispersion (LD)) with large metal particles. The CO tolerance of PtRu/C (HD) was higher than that of any commercial PtRu/C. The high CO tolerance of PtRu/C (HD) is thought to be due to efficient concerted functions of Pt, Ru, and their alloy.

Hydrodechlorination of CCl4 on Pt–Au/Al2O3 Catalysts

A series of Pt/Al2O3 catalysts were prepared by the impregnation method and were characterized by TEM, XRD, H2 and CO chemisorptions, and investigated in the hydrodechlorination of tetrachloromethane. Three Pt-rich, Pt–Au/Al2O3 catalysts (Pt100, Pt95Au5 and Pt90Au10) showed a similar metal particle size (~2.5–2.7 nm), so observed changes in the catalytic behavior are ascribed to alloying effect, especially because a considerable degree of Pt–Au mixing was achieved in the bimetallic samples. It appeared that by introducing very small amount of gold (10 at.%) to platinum, the catalytic activity is increased. It is argued that the occurrence of this moderate synergistic effect is associated with a decreased tendency of surface chloriding when platinum is alloyed with gold.

Preparation and Characterization of a PtSn Nanocatalyst for Use in Ethanol Electro-Oxidation

A PtSn nanocatalyst supported on carbon (PtSn) was prepared with the enhancement of the extent of alloy degree of Pt with Sn by the heat treatment at 300 degrees C in a nitrogen atmosphere (PtSn/C-HT). The PtSn and PtSn/C-HT catalysts prepared were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electrochemical methods, and were tested as an electro-catalyst in ethanol electro-oxidation. Results showed that the average particle size of the PtSn/C-HT was increased by the heat treatment, compared to that of PtSn. The catalytic activity of PtSn/C-HT, however, was superior in ethanol electro-oxidation. The enhanced catalytic activity of PtSn/C-HT was attributed to both the high degree of alloying in the PtSn structure and the extended Pt lattice, which promote catalytic activities in ethanol electro-oxidation and removal of intermediate CO species.

SiO 2 nanotubes with nanodispersed Pt in the walls

SiO 2 nanotubes (NTS) of different wall thickness were prepared using fibres of [Pt(NH 3) 4](HCO 3) 2 salt crystals. During growth of the SiO 2 nanotube walls by sol–gel condensation from tetraethyl orthosilicate (TEOS) on the surface of the templating Pt–salt fibres parts of the salt nanocrystals are incorporated into the walls due to strong SiO 2–salt interaction. This leads to a significant softening in the vibration density of states (VDS) of SiO 2. With increasing thickness of the SiO 2 NT walls the degree of Pt–salt incorporation decreases and consequently the observed shifting of IR Si–O vibration bands is more pronounced for NTs with thinner walls. In all cases the VDS relaxes during calcinations to those of pure SiO 2. Calcination leads to the formation of Pt nanoparticles and micropores within the nanotube walls.

One-step conversion of n-butane to isobutene over H-beta supported Pt and Pt,M (M = Cu, In, Sn) catalysts: An investigation on the role of the second metal

The one-step transformation of n-butane to isobutene was studied over H-beta zeolite supported Pt and Pt,M (M = Cu, In, Sn) catalysts. Catalytic performance of monometallic Pt/H-beta samples resulted to be affected by the support acidity, a lower number of acid sites leading to higher iso- and n-butenes selectivities and lower by-products formation. Addition of Cu, In or Sn to Pt enhanced both isobutene and n-butenes selectivities, which were in the order: Pt,In > Pt,Sn ≫ Pt,Cu > Pt. All Pt,M samples exhibited also a higher stability than the corresponding monometallic Pt samples, the sequence of deactivation rates being: Pt > In,Pt > Cu,Pt ≈ Sn,Pt. On the basis of characterization results it was stated that the addition of Cu, In or Sn to Pt affects the n-butane dehydroisomerization modifying both the surface structure of Pt clusters and the support acidity. In particular the observed order of isobutene selectivity was related to the degree of Pt–M interaction leading to a dilution of Pt clusters, which inhibits hydrogenolysis reactions and enhances dehydrogenation processes. The decrease in the number of acid sites caused by addition of the second metal was instead accounted for the improved resistance to deactivation of Pt,M catalysts.

Pyridinium-derived N-heterocyclic carbene complexes of platinum: synthesis, structure and ligand substitution kinetics.

A series of [(R-iso-BIPY)Pt(CH(3))L ](+)X(-) complexes [R-iso-BIPY = N-(2-pyridyl)-R-pyridine-2-ylidene; (R = 4-H, 1; 4-tert-butyl, 2; 4-dimethylamino, 3; 5-dimethylamino, 4); L = SMe(2), b; dimethyl sulfoxide (DMSO), c; carbon monoxide (CO), d; X = OTf(-) = trifluoromethanesulfonate and/or [BPh(4)](-)] were synthesized by cyclometalation of the [R-iso-BIPY-H](+)[OTF](-) salts 1a-4a ([R-iso-BIPY-H](+) = N-(2-pyridyl)-R-pyridinium) with dimethylplatinum-micro-dimethyl sulfide dimer. X-ray crystal structures for 1b, 2c-4c as well as complexes having bipyridyl and cyclometalated phenylpyridine ligands, [(bipy)Pt(CH(3))(DMSO)](+) (5c) and (C(11)H(8)N)Pt(CH(3))(DMSO) (6c), have been determined. The pyridinium-derived N-heterocyclic carbene complexes display localized C-C and C-N bonds within the pyridinium ligand that are indicative of carbene pi-acidity. The significantly shortened platinum-carbon distance, for "parent" complex 1b, together with NMR parameters and the nu(CO) values for carbonyl cations 1d-4d support a degree of Pt-C10 multiple bonding, increasing in the order 3 < 4 < 2 < 1. Degenerate DMSO exchange kinetics have been determined to establish the nature and magnitude of the trans-labilizing ability of these new N-heterocyclic carbene ligands. Exceptionally large second-order rate constants (k(2) = 6.5 +/- 0.4 M(-1).s(-1) (3c) to 2300 +/- 500 M(-1).s(-1) (1c)) were measured at 25 degrees C using (1)H NMR magnetization transfer kinetics and variable temperature line shape analysis. These rate constants are as much as 4 orders of magnitude greater than those of a series of structurally similar cationic bis(nitrogen)-donor complexes [(N-N)Pt(CH(3))(DMSO)](+) reported earlier, and a factor of 32 to 1800 faster than an analogous charge neutral complex derived from cyclometalated 2-phenylpyridine, (C(11)H(8)N)Pt(CH(3))(DMSO) (k(2) = 0.21 +/- 0.02 M(-1).s(-1) (6c)). The differences in rate constant are discussed in terms of ground state versus transition state energies. Comparison of the platinum-sulfur distances with second order rate constants suggests that differences in the transition-state energy are largely responsible for the range of rate constants measured. The pi-accepting ability and trans-influence of the carbene donor are proposed as the origin of the large acceleration in associative ligand substitution rate.

Optical transmittance study of the thermal decomposition of sputtered Pt–Ag–O films

Platinum was doped into Ag–O to prepare Pt–Ag–O (Pt composition: 1–5 at.%) film, and its thermal decomposition process was studied by measuring the change in transmitted light intensity while heating the film to 600 °C. X-ray fluorescence spectroscopy was used to evaluate the oxygen loss up to 260 °C. When 1 at.% Pt was doped, the AgO to Ag 2O decomposition process at 130–160 °C became less evident. When Pt composition was further increased, oxygen loss was somewhat suppressed, at least up to 260 °C, and a slight degree of Pt–O thermal decomposition became noticeable at approximately 550 °C. Platinum doping effectively modified the Ag–O thermal decomposition process, and giving it potential for use as a temperature control for plasmon-related techniques activated by the generation of Ag particles.

Orientation control in PZT/Pt/TiN multilayers with various Si and SiO2 underlayers for high performance ferroelectric memories

To suppress fluctuation in capacitor characteristics, highly oriented lead zirconate titanate (or PbZrxTi1−xO3 (PZT) films are required in ultralarge scale ferroelectric memories whose capacitor size is comparable to PZT grain size. The (111) orientation, which is closely related to spontaneous polarization, is achieved when PZT film is grown on highly (111) oriented platinum film. The degree of Pt(111) orientation is dependent on the crystallinity of the underlying TiN barrier metal. Furthermore, the crystallinity of the TiN is strongly dependent on the type of underlying material. The crystallinity of the TiN film grown on amorphous Si is much better than the crystallinity achieved on thermally oxidized Si. The surface energy difference between the TiN and underlayer may affect the growth mode of the TiN films. The crystallinity of the TiN film on rougher Si surfaces, such as in situ crystallized poly-Si, is inferior to the crystallinity observed on amorphous Si. Therefore, a smooth Si buffer layer is required underneath the capacitor to improve performance of the PZT/Pt/TiN capacitor. The modified planarized stacked structure presented in this article uses a postannealed crystalline Si as a buffer layer underneath the capacitor.

Bimetallic Particle Formation in Pt–Re/Al2O3Reforming Catalysts Revealed by Energy-Dispersive X-Ray Spectrometry in the Analytical Electron Microscope

The metal function of a commercial 0.3–0.3 wt% Pt–Re/Al2O3catalyst was studied by scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectrometry (EDX). Evidence for platinum–rhenium bimetallic particle formation in the reduced catalyst has been established. The degree of Pt–Re interaction is highly dependent on the conditions employed during catalyst pretreatment. The highest degree of Pt–Re interaction is obtained if the catalyst is not dehydrated prior to reduction. High-temperature N2treatment causes platinum oxide decomposition, sintering, and a low degree of Pt–Re interaction. The part of the rhenium not associated with platinum is possibly distributed on the surface of the alumina support as submicroscopic particles.