Surface Properties Of Support Research Articles

Immobilization of Cyclodextrin glycosyltransferase onto three dimensional- hydrophobic and two dimensional- hydrophilic supports: A comparative study.

Cyclodextrin glycosyltransferase (CGTase) degrades starch into cyclodextrin via enzymatic activity. In this study, we immobilize CGTase from Thermoanaerobacter sp. on two supports, namely graphene nanoplatelets (GNP) consisting of short stacks of graphene nanoparticles and a calcium-based two-dimensional metal organic framework (Ca-TMA). The uptakes of CGTase on GNP and Ca-TMA reached 40 and 21mg g-1 respectively, but immobilized CGTase on Ca-TMA showed a higher specific activity (38 U mg-1 ) than that on GNP (28 U mg-1 ). Analysis of secondary structures of CGTase, shows that immobilization reduces the proportion of β-sheets in CGTase from 56% in the free to 49% and 51.3% for GNP and Ca-TMA respectively, α-helix from 38.5% to 18.1 and 37.5%, but led to increased β-turns from 5.5 to 40% and 11.2% for GNP and Ca-TMA, respectively. Lower levels of conformational changes were observed over the more hydrophilic Ca-TMA compared to hydrophobic GNP, resulting in its better activity. Increased β-turns were found to correlate with lower β-CD production, while more β-sheets and α-helix favored more β-CD. Reusability studies revealed that GNP retains up to 74% of initial CGTase activity, while Ca-TMA dropped to 33% after eight consecutive uses. The results obtained in this work provide insight on the effect of support's surface properties on CGTase performance and can assist in developing robust CGTase-based biocatalysts for industrial application.

Quantitative Description of Metal Center Organization and Interactions in Single-Atom Catalysts.

Ultra-high-density single-atom catalysts (UHD-SACs) present unique opportunities for harnessing cooperative effects between neighboring metal centers. However, the lack of tools to establish correlations between the density, types, and arrangements of isolated metal atoms andthe support surface properties hinders efforts to engineer advanced material architectures. Here, this work precisely describes the metal center organization in various mono- and multimetallic UHD-SACs based on nitrogen-doped carbon (NC) supports by coupling transmission electron microscopy with tailored machine-learning methods (released as a user-friendly web app) and density functional theory simulations. This approach quantifies the non-negligible presence of multimers with increasing atom density, characterizes the size and shape of these low-nuclearity clusters, and identifies surface atom density criteria to ensure isolation. Further, it provides previously inaccessible experimental insights into coordination site arrangements in the NC host, uncovering a repulsive interaction that influences the disordered distribution of metal centers in UHD-SACs. This observation holds in multimetallic systems, where chemically-specific analysis quantifies the degree of intermixing. These fundamental insights into the materials chemistry of single-atom catalysts are crucial for designing catalytic systems with superior reactivity.

Investigating the impact of dynamic structural changes of Au/rutile catalysts on the catalytic activity of CO oxidation

AbstractThe surface properties of oxidic supports and their interaction with the supported metals play critical roles in governing the catalytic activities of oxide‐supported metal catalysts. When metals are supported on reducible oxides, dynamic surface reconstruction phenomena, including strong metal–support interaction (SMSI) and oxygen vacancy formation, complicate the determination of the structural–functional relationship at the active sites. Here, we performed a systematic investigation of the dynamic behavior of Au nanocatalysts supported on flame‐synthesized TiO2, which takes predominantly a rutile phase, using CO oxidation above room temperature as a probe reaction. Our analysis conclusively elucidated a negative correlation between the catalytic activity of Au/TiO2 and the oxygen vacancy at the Au/TiO2 interface. Although the reversible formation and retracting of SMSI overlayers have been ubiquitously observed on Au/TiO2 samples, the catalytic consequence of SMSI remains inconclusive. Density functional theory suggests that the electron transfer from TiO2 to Au is correlated to the presence of the interfacial oxygen vacancies, retarding the catalytic activation of CO oxidation.

Effect of TiO2-Al2O3 support surface properties on active phase structure and hydrodenitrogenation performances of the corresponding NiWS supported catalysts

To explore the effect of the support surface properties on the active phase structure and the hydrodenitrogenation (HDN) catalytic performance of the corresponding hydrotreating (HDT) catalyst, three kinds of TiO2-Al2O3 supports with a Ti/Al molar ratio of 1 but different Ti-Al composite result were prepared by the following methods: the mechanical mixing method (T + A), the ion-exchange method (T/A) and the in-situ synthesis method (TA). The Ti-Al composite results of the supports were characterized by XRD, FTIR, SEM-Mapping and N2 physical adsorption–desorption techniques and the properties of the NiW supported catalysts were determined by XRD, H2-TPR, HRTEM and XPS. The results show that the surface properties of TiO2-Al2O3 composite supports can be modulated by changing the Ti modification method. Among all the three methods, the in-situ synthesis method can achieve the atomic mixing of titanium and aluminum elements to maximize the Ti-O-Al bonds, followed by the ion-exchange method, and finally the mechanical mixing method. Accordingly, the number of Ti-O-Al bonds in the support determines the dispersion, stacking and sulfurization of the active phase. When more Ti-O-Al bonds are present in the support, the higher the dispersion and sulfurization degrees of the active metals and the stacking layer number of the NiWS active phase in the catalyst, thus exhibiting higher HDN activity both for basic and non-basic nitrides. In addition, Ti3+ species can be generated when enough Ti-O-Al bonds are present in the support surface, which also enhance the promotion of the sulfidation degrees of the active metal and the formation of CUS and thus further improve the HDN activity. Generally, the in-situ Ti modification method was considered to be the favorable method for preparing highly active HDT catalysts due to its excellent Ti-Al composite surface properties.

Activated carbon supported nickel catalyst for selective CO2 hydrogenation to synthetic methane under contactless induction heating

The use of CO2 methanation in the power-to-gas (PtG) technology chains has received increasing attention in recent years for clean energy and sustainable development. In this work, macroscopic mesoporous nickel catalyst was prepared and evaluated for selective CO2 hydrogenation to CH4 using commercial activated carbon (AC) pellets. Catalyst samples were fully characterized by liquid N2 adsorption-desorption, X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), scanning and transmission electron microscopy (SEM/TEM). Catalytic performances were investigated under various reaction conditions with both direct induction heating (IH) and conventional indirect Joule heating (JH) modes. Results indicated that by simple thermal treatment, the surface and textural properties of the macroscopic carbon support could be greatly modified by improving the dispersion of metal sites and thus the catalytic performance. The advantages of IH combined with the inherent high thermal and electrical conductivity of the prepared materials could effectively avoid the temperature runaway and enhance the CO2 activation at relatively low reaction temperature. By comparison to the classical indirect JH mode, the resulting macroscopic nickel catalysts showed improving catalytic performances for CO2 methanation under IH mode. The efficient heat management under direct IH mode also prevented coke formation on the catalyst surface which contributes to its high stability as a function of time-on-stream.

Efficient preparation of phytase from genetically modified Pichia pastoris in immobilised fermentation biofilms adsorbed on surface-modified cotton fibres

Compared with the traditional suspension fermentation, immobilised biofilm fermentation has advantages of strong resistance, high yield and continuous fermentation and is conducive to improving the industrial fermentation methods. The formation of a biofilm on correct supports is critical to immobilised fermentation. In this study, Pichia pastoris was used to understand and control the modification of surface properties of supports and cells. Following deletion of gene PAS_chr2-1_0773, in P. pastoris △0773, the cell-surface negative charge density decreased and hydrophobicity improved, which was conducive to adhesion. Therefore, according to the changing trend of cell surface properties, cotton fibre was used with succinic anhydride (SA) to modify the carrier for changing the surface properties for efficient conduction of immobilised fermentation. In the fermentation process, the adhesion between the modified cotton fibre and yeast was better than that between an unmodified cotton fibre and yeast, and the additive amount increased by ∼25 %. The enzyme activity of the △0773-cotton-SA fermentation system reached 302.7 U/mL, which was 39.6 % higher than that of the original fermentation system. Therefore, this study provides a guide for significant improvement of immobilised fermentation of fungi.

Effect of Support Surface Properties on CO2 Capture from Air by Carbon-Supported Potassium Carbonate

Direct CO2 capture from air is of prime importance to mitigate the negative effects of global warming. Potassium carbonate (K2CO3) is a promising sorbent for the capture of CO2 from air. K2CO3 chemisorbs CO2 from air in the presence of water (the so-called carbonation reaction), even in very low concentrations (410 ppm). To make efficient use of K2CO3, it is dispersed on a support. Carbon-based supports are promising because of their high hydrothermal stability. Carbons have different structural and chemical properties; however, these can be tuned during preparation. Little is known about the relation between carbon properties and their performance, after K2CO3 deposition. We investigated the role of support surface composition on the performance of carbon-supported K2CO3. By using carbons with different numbers of surface oxygen groups, that is, different polarities, we show that K2CO3 supported on an apolar carbon results in a higher capacity CO2 capture. We propose that a polar support attracts polar H2O molecules on the K2CO3 sorbent, resulting in a low carbonation. In contrast, an apolar support lowers the local H2O concentration on the sorbent and favorably attracts apolar CO2 molecules, hence promoting carbonation.

Improved enzymatic activity by oriented immobilization on graphene oxide with tunable surface heterogeneity

The precision design of surface properties of supports and immobilization methodologies is essential for improving the biocatalytic activity of immobilized enzymes. In this study, we proposed a surface heterogeneity regulation strategy of graphene oxide (GO) to oriented immobilize adenylate cyclase (AC). The grafted flexible chain of polyethylene glycol amine (PEG-NH2) and maleic anhydride (MAH) on GO surface can adjust the interaction between support and AC. The achieved immobilized AC can eliminate the non-specific adsorption and introduce cushioning effect for the AC's catalytic reaction under extreme conditions. Therefore, the active center of the enzyme can be retained. The introduction of PEG-NH2 improves the activity recovery with 113%. Compared to GO-Ni2+@ AC, 8 arm-PEG-NH2 modified GO immobilized AC has 117 times higher catalytic activity. The method proposed in this study provides a possibility to address the issues in enzyme application, such as the purification of enzyme, low enzyme activity caused by cross-linking, and non-specific adsorption due to molecular force on the surface of the supports. The strategy should provide deeper understanding of the oriented immobilization and support modification for improving the activity and stability of the immobilized enzyme.

Highly dispersed Ni2P clusters inlaid in micropore openings on mesoporous ZSM-5 zeolite and its catalytic performance in the phenylacetylene semi-hydrogenation

Preparation of Ni2P phase with cluster size and high stability is significant for enhancing its catalytic performance. Herein, Ni2P nanoclusters (<1nm) inlaid in micropore openings on mesoporous ZSM-5 zeolite (MZSM-5) was prepared through citric acid-assisted, two-step impregnation method under the reduction temperature of 400°C. The facilitation effect of the citric acid and support surface properties on the formation of Ni2P clusters was investigated. The formation of Ni(H2cit)+ complex promotes the dispersion of the Ni precursor on the zeolite surface. After calcination, the free Ni species interact stronger with the acidic hydroxyl groups on MZSM-5 than that with silanol on mesoporous TS-1(MTS-1), Silicalite-1 (MSilicalite-1) and SiO2, facilitating the formation of Ni2P nanoclusters on the MZSM-5 micropore openings after the calcined Ni catalyst was loaded with P species and followed by activation treatment. The obtained Ni2P clusters exhibit higher intrinsic activity (robs=1.50molkg−1s−1) than MTS-1, MSilicalite-1 and SiO2 supported Ni2P catalysts (0.80, 0.76, 0.40molkg−1s−1) in the semi-hydrogenation of phenylacetylene.

The influence of hydrophobicity on Fischer-Tropsch synthesis catalysts

Abstract We review scientific works carried out on the influence of surface hydrophobicity on activity and product selectivity of supported cobalt and iron catalysts during Fischer-Tropsch synthesis (FTS). The characteristics of the surface of catalyst support may influence metal-support interactions, which leads to various degrees of metal dispersion and reducibility. Also, these support surface properties may influence the mass transfer of reactants and products at the catalyst active sites and subsequently affects the performance of the catalyst during FTS. Pre-silylated and post-silylated catalysts have been used to study the influence of surface hydrophobicity on the performance of FTS catalysts. The enhancement of FTS activity by hydrophobicity was mainly ascribed to the improved reducibility of metal oxide species. Furthermore, post-silylated supported iron catalysts favoured the suppression of water-gas shift (WGS) reaction, thereby hindering CO2 formation.

Iron catalysts supported on nitrogen functionalized carbon for improved CO2 hydrogenation performance

Preparation of highly efficient Fe-based catalysts is a reliable and achievable goal for catalyzing CO2 hydrogenation. Herein, ethylene diamine as a benign modifier well regulates the surface properties of carbon support, achieving a good dispersion of active small-size iron carbide sites. With the further incorporation of alkaline K promoter, heavy hydrocarbon selectivity (C5+) is increased from 14.8% to 39.8%. Combining several catalyst characterization (XRD, CO2-TPD, H2-TPR, TEM, and XPS) and reaction data, discloses that good dispersion, enhanced reduction/carburization behavior, and small-size carbides formation are essential for improving CO2 performance. Simultaneous doping of nitrogen atoms and alkali metal provides a promising means for CO2 fixation and rational design of functionalized metal-supported carbon catalysts.

Experimental probing of effects of carbon support on bulk and local oxygen transport resistance in ultra-low Pt PEMFCs

Carbon support not only promises to dispersedly anchor Pt-based metal nanoparticles but also functions as the critical component of catalyst layers (CLs) in polymer electrolyte membrane fuel cells (PEMFCs). Thus, the geometrical and surface properties of carbon support are believed to impact the mass transport greatly, especially the local oxygen transport in ultra-low Pt PEMFCs. Herein, we explore influences of carbon support on oxygen transport resistance in cathode catalyst layers (CCLs) through combining the limiting current method with a dual-layer CCL design. Results demonstrate that the properties of carbon support have a more significant effect on the local oxygen transport resistance relative to the bulk one. Based on various advanced physicochemical characterizations, it is analyzed that the geometrical morphology of carbon support influences the bulk oxygen transport resistance via featuring the pore structure in the electrode, while the surface functional groups of carbon support influence the local oxygen transport resistance via determining the distribution of ultra-thin ionomer films on the catalyst surface. It is believed that the findings on the interaction between carbon support and cathode mass transport behavior give a critical enlightenment on the design of high performance ultra-low Pt membrane electrode assemblies (MEAs).

Improved catalytic performance of CrOx catalysts supported on foamed Sn-modified alumina for propane dehydrogenation

To better understand influences of surface properties of supports on distributed Cr active sites of Cr-based catalysts with high Cr loading, foamed alumina modified by Sn was prepared to support CrO x catalysts for propane dehydrogenation. N 2 adsorption-desorption, TEM, XRD, FTIR, UV–vis, Raman, XPS, NH 3 -TPD, Py-IR and H 2 -TPR were carried out to elucidate catalyst structures. The foamable alumina is formed by using soft template, and tin added in preparing process changes micro-micelle formation to generate more complex cavity structure. The Sn doped into alumina framework and dispersed on support surface changes the surface properties, such as surface hydroxyl group and isoelectric point, promoting the formation of more active polymeric chromate on the surface, thus the CrO x supported on modified alumina presents high activity of propane dehydrogenation and good catalyst stability, comparing with unmodified CrO x /alumina catalyst. The added Sn obviously inhibits the formation of coke deposition due to decreased strong acid sites, Cr sites density and Cr 3+ content on the surface of the catalysts. • Foamed alumina modified by tin is prepared for supporting CrO x catalysts. • The adding tin increases the pore size and develops more complex cavity structure. • Doped and dispersed tin on surface change interaction between Cr and support. • Propane dehydrogenation performance is enhanced by using modified alumina as support. • Tin obviously inhibits formation of coke and increases catalyst stability.

Designed synthesis of highly active CeO2-ZrO2-Al2O3 support materials with optimized surface property for Pd-only three-way catalysts

In this work, a series of CeO2-ZrO2-Al2O3 (CZA) support materials were prepared by co-precipitation method combing with hydrothermal treatment at different temperatures. Then their supported Pd-only three-way catalysts (TWCs) were prepared, characterized and compared with commercial Pd/CZAS catalyst. It is found that the catalytic performance of Pd-only TWCs shows a strong dependence on the surface properties rather than the bulk structures of CZA supports. Higher hydrothermal temperatures promote the self-assemble of Al2O3 into nanorods, and the formation of CeO2-ZrO2 (CZ) solid solution with larger crystal size, which widens the pore size distribution of CZA and improves the thermal stability of CZ nanoparticles with lower growth rate, respectively. However, the specific surface area, surface oxygen vacancies and surface Ce content of CZA decrease with hydrothermal temperature rising, which in return decreases the activity of the Pd/CZA catalysts. While it should also be noted that all the as prepared Pd/CZA exhibit better activity than the commercial Pd/CZAS, and the T50 (temperature for 50% conversion) for CO, NO, C3H6, C3H8 over Pd/CZA100 are 48 °C, 30 °C, 26 °C and 31 °C lower than those for Pd/CZAS, respectively. It further indicates that highly active Pd-only TWCs could be constructed by optimizing the surface properties of CZA support via hydrothermal treatment at modern temperature.

Morphology change and phase transformation of alumina related to defect sites and its use in catalyst preparation

• The morphology and phase changes in γ-Al 2 O 3 during wet impregnation. • The morphology and phase changes are related with defect (Al V ) sites on alumina. • Controlling the catalyst preparation is important to understand catalyst properties. The surface properties of support have a large influence on the catalyst properties and the catalyst properties are usually interpreted based on the characterization results of the support surface. However, in many cases, especially when γ-Al 2 O 3 is used as the support, the alumina surface can be changed during catalyst preparation. Here, the significant changes in the physical and chemical properties of γ-Al 2 O 3 were observed during catalyst preparation by using incipient wetness impregnation, which follows the general protocols of catalyst production. These changes were confirmed with transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses. To investigate the origin of such changes from hydrolysis, low-crystalline γ-Al 2 O 3 (A600) was prepared, which has abundant defect sites (Al V ) on its surface and bulk. Through 27 Al magic angle spinning nuclear magnetic resonance (MAS-NMR) and XRD studies, it could be demonstrated that defect sites (Al V ) play a crucial role in the hydrolysis of alumina. Further, the hydrolysis of the alumina surface could be controlled by altering the solvent properties like changing the volume ratio of ethanol. These results suggest that the change in the support's surface during the catalyst preparation should be considered carefully when correlating the characteristics of the alumina surface with the characteristics of an alumina-based catalyst.

Formation of isolated tungstate sites on hierarchical structured SiO2- and HY zeolite-supported WOx catalysts for propene metathesis

The formation of isolated tungstate sites on hierarchical structured SiO2 nanoparticles and HY zeolite with high Si/Al ratio (Si/Al 500) was investigated in the self-metathesis of propene over supported WOx-based catalysts. The synthesis of hierarchical HY not only increased the tungsten dispersion in the forms of isolated tungstate oxo species (mono-oxo and di-oxo) by increasing the terminal silanol group density of the support for these oxides to be grafted on but also greatly reduced the heavy hydrocarbon formation simultaneously by elimination of some alumina from the zeolite. As a consequence, higher propene conversion was obtained without the undesired reactions especially during the initial stage, when the metallocarbene was not fully developed. The results present a facile method for the development of heterogeneous WOx-based metathesis catalysts and a better correlation between the surface properties of catalyst support and the formation of tungsten pre-catalysis active species.

Pt/Al2O3 with ultralow Pt-loading catalyze toluene oxidation: Promotional synergistic effect of Pt nanoparticles and Al2O3 support

A kind of highly efficient and low cost supported-Pt catalyst for oxidation of toluene is obtained through controlling both the chemical state of Pt active sites and surface properties of supports. The optimized Pt/Al2O3 catalyst with Pt loading as low as 0.1 wt% could completely convert toluene (1000 ppm) to CO2 at about 180 ℃ under a space velocity of 24,000 mL g−1 h−1. It also exhibits a high stability and moisture resistance properties under reaction atmosphere. TOF value calculated with the dispersion of Pt can reach 0.0685 s-1, representing a high utilization efficiency of Pt. A series of characterizations are carried out to investigate the key factors affecting the catalytic performance of Pt/Al2O3, and disclose the concrete role of Pt and Al2O3 in the activation of molecular oxygen and toluene. In situ DRIFTS and EPR results show that Pt is the active center for O2 activation. Metallic Pt nanoparticles (Pt0) can activate the molecular O2 even at room temperature. Al2O3 offers sites for the adsorption of toluene and desorption of CO2 product. The weak and medium strength of acid-base sites favorite the adsorption and desorption process. The oxidation of toluene over Pt/Al2O3 obeys modified L-H mechanism. The synergistic effect of metallic Pt nanoparticles and suitable Al2O3 support is critical for obtaining highly efficient Pt-based catalysts with low Pt contents for toluene oxidation.

Glycerol and formic acid electro-oxidation over Pt on S-doped carbon nanotubes: Effect of carbon support and synthesis method on the metal-support interaction

The effects of catalyst support and synthesis process on the interaction between Pt nanoparticles (NPs) and S-doped carbon nanotubes (SCNTs), and the resultant electro-oxidation catalytic performance of glycerol, formic acid and CO were systematically researched. Pt NPs on SCNTs had better electro-oxidation catalytic performances than that of Pt NPs on CNTs. The doped S in thiophene-like structure (C-S-C) activated the neighboring C atoms to interact with Pt NPs, improving the catalytic performance with stronger ability to remove poisonous intermediates. The formed C-S-C had a synergistic effect with the neighboring Pt-C, promoting the adsorption and activation of reactants. The improved metal-support interaction resulted in Pt with smaller nanoparticle size and more exposed active sites. In different synthesis process, Pt NPs were more likely to interact with activated C neighboring S in ethylene glycol reduction method. However, defects containing doped S preferred to interact with Pt NPs in impregnation method. The research results indicated that rationally regulating the surface properties of carbon support and choosing an appropriate catalyst synthesis strategy to intensify the required metal-support interaction can greatly improve the catalytic performance.

Improvement of lipase activity by synergistic immobilization on polyurethane and its application for large-scale synthesizing vitamin A palmitate

We have developed an improved and effective method to immobilize lipase on hydrophobic polyurethane foam (PUF) with different modifications. PUF was treated with hydrochloric acid to increase the active sites and then the active carboxyl groups and amino groups were exposed. Enzyme activity of lipase immobilized on PUF-HCL (8000 U/g) was 50% higher than that of lipase immobilized on PUF (5300 U/g). There is an increase in the activity of the immobilized lipase on AA/PEI-modified support (115,000 U/g), a 2.17-fold increase compared to lipase immobilized on the native support was observed. The activity of immobilized lipases was dependent on the PEI molecular weight, with best results from enzyme immobilized on PUF-HCL-AA/PEI (MW 70,000 Da, 12,800 U/g)), which was 2.41 times higher compared to that of the same enzyme immobilized on PUF. These results suggest that the activity of immobilized lipase is influenced by the support surface properties, and a moderate support surface micro-environment is crucial for improving enzyme activity. Finally, the immobilized lipase was used for the production of vitamin A palmitate. The immobilized lipase can be reused for up to 18 times with a conversion rate above 90% for 12 h in a 3 L bioreactor.Research highlightsAn efficient immobilization protocol on polyurethane foam was developedPolyethyleneimine and acetic acid were used to regulate the micro-environment concurrentlyThe activity of lipase immobilized on PUF-HCL-AA/PEI was improved by 2.41 timesImmobilized lipase exhibited excellent operational stability for vitamin A palmitate synthesis

Controlling the acid-base properties of alumina for stable PtSn-based propane dehydrogenation catalysts

The surface properties of catalyst supports are important in regulating the catalytic properties of heterogeneous catalysts. Herein, we studied the effect of acid-base properties of alumina on metal-support interaction and coke deposition, and investigated the stability of catalysts in propane dehydrogenation (PDH) using PtSn/Al2O3. We prepared γ-Al2O3 (A750) from ammonium aluminum carbonate hydroxide (AACH) and compared it with a commercial sample (Sasol Puralox SBA-200; P200). We loaded 0.5 wt% Pt and 0.9 wt% Sn on alumina then conducted propane dehydrogenation at 590 °C (WHSV = 5.2 h−1). PtSn/A750 and PtSn/P200 showed compatible initial activity (conversion = ˜50%) and selectivity (> 95%). After 20 h of reaction, PtSn/A750 showed a slight decrease in activity (39.9%) while the activity of PtSn/P200 dropped significantly (28.4%). Spent catalysts showed different metal sintering behavior and coke deposition which are well known causes for catalyst deactivation. A high strength of Lewis acid sites in A750 (higher Td in ethanol TPD) prevented the sintering of metal by strong metal-support interaction. Also, the lower number of Lewis acid sites in A750 than that of P200 reduced deposited coke on the catalysts (PtSn/A750: 1.8 wt% and PtSn/P200: 8.6 wt%). Furthermore, diffuse reflectance infrared Fourier-transform spectroscopy after CO adsorption at -150 °C clearly demonstrated that coke deposition was initiated from Lewis acid sites on the alumina surface, but then aromatization occurs at these sites. These results suggested that strong metal-support interactions to hold metal particles and less residual Lewis acid sites after metal loading to reduce coke deposition are important factors for designing stable and coke-resistant PtSn on alumina catalysts. Furthermore, precise characterization and understanding of the acid-base properties of alumina will contribute in developing catalysts with high stability.