Calcination Temperature Of Support Research Articles

A detailed characterization study of Ni/CeO2 catalysts identifies Ni availability as the primary factor affecting CO2 methanation performance

The structure of a catalyst has a strong impact on its performance. Here we investigate the physicochemical properties of Ni/CeO2 in an attempt to draw structure–activity relationships for CO2 methanation. A combination of characterisation methods (X-ray diffraction (XRD), 4D Scanning Transmission Electron Microscopy (4D-STEM), CO chemisorption and oxygen storage capacity study etc.) clearly demonstrates the effect of Ni crystallite size, Ni availability (i.e. catalytically accessible Ni) and oxygen vacancies at the Ni-CeO2 interface in Ni/CeO2 during CO2 methanation. Among them, the role of exposed Ni active sites is highlighted, and two possible optimisation schemes i.e. changing the support calcination temperature and the final calcination atmosphere are proposed to obtain a better dispersal of Ni NPs (nanoparticles) on CeO2. Both modification methods do not affect the reaction route, and the activity differences of Ni/CeO2 can be explained by the various hydrogenation rate of formate species, as confirmed by in situ diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFTS) measurements.

Defective Auδ−-Ov interfacial sites boost C-H bond activation for enhanced selective oxidation of amino alcohols to amino acids

Designing efficient active sites to facilitate the oxidation of hydroxyl group to carboxylic acid under the influence of nitrogen-containing functional groups is worth exploring, but it is rarely investigated. Herein, we construct defective Au-ZrO2 interfacial structures by tuning the calcination temperature of ZrO2 support to boost the oxidation of amino alcohols to amino acids. Interestingly, the modification of calcination temperature induces the escape of saturated coordination oxygen atoms in ZrO2 support, leaving behind abundant surface oxygen vacancy (Ov). The as-formed Auδ−-Ov interfacial site displays the unique synergistic adsorption effect and electron transfer ability. Specifically, the Ov site voluntarily adsorbs the –NH2 group of amino alcohol, thus ensuring that the electron-rich Auδ− nearby Ov site adsorbs the hydroxyl groups and activates the C-H bond activation of NH2CH2CH2O* intermediates. Consequently, Au/ZrO2-600 catalyst with more defective Auδ−-Ov interfacial sites exhibits 98.8 % product yield for the oxidation of diethanolamine to iminodiacetic acid at only 30 °C. The catalyst system is further extended to the oxidation of other amino alcohols, involving monoethanolamine and triethanolamine, to their corresponding amino acids with excellent catalytic performance.

Utilization of Salmon fish bone wastes as a novel bio-based heterogeneous catalyst-support toward the production of biodiesel: Process optimizations and kinetics studies

This study investigated the feasibility of using calcined Salmon fish bone wastes as an inexpensive and reusable catalyst-support for the biodiesel production via transesterification of sunflower oil. In this venue, a series of catalysts were synthesized by impregnating potassium hydroxide (KOH) onto the calcined Salmon fish bones. The as-prepared catalysts were characterized through several techniques, including the FESEM, BET-BJH, TGA, FT-IR, and XRD. In this regard, the effects of the calcination temperature of the waste Salmon fish bone, KOH loading amount, and the calcination temperature of KOH-impregnated support upon the catalytic activity of the final catalyst were understudied. Results displayed that the calcination temperature of fish bones at 1273 K with 40 wt% of KOH loading, which was calcined at 873 K, led to the highest catalytic performance. For this optimum material, the effects of the parameters, such as the catalyst loading, the methanol: oil molar ratio, and the reaction time and temperature upon the biodiesel production yield were examined. It was determined that the optimum operating conditions for the reaction included the catalyst loading of 10 wt%, the methanol: oil molar ratio of 10:1, and the reaction temperature of 338 K for 3 h. The gas chromatography and 1HNMR analyses revealed an optimum biodiesel production yield of 99.13 %. This result is attributed in part to a rather high basicity of the aforementioned optimum material. Moreover, this optimum species was shown to endure four consecutive reaction cycles, whereas its activity dropped by about 10 %. Furthermore, the chemical kinetic parameters of the reaction using this catalyst were determined to be; the reaction rate constant of 0.45 h−1 and its respective activation energy of 67.01 kJ/mol. Ultimately, it was demonstrated that neither internal nor external mass transfer limitations existed in the heterogeneous system considered in this research hence, all observed behaviors were solely due to chemical kinetics.

Highly efficient MnOx catalysts supported on Mg-Al spinel for low temperature NH3-SCR

Selective catalytic reduction (SCR) has been extensively employed in industries for the removal of NOx while it is still a challenge to develop novel low-temperature catalysts. The redox and acid sites on the catalyst are often preconditions that cooperate in the SCR reaction. In this study, a series of MnOx supported on MgAl2O4 spinel catalysts (denoted as Mn/MAS) were successfully prepared by incipient wetness impregnation method for low-temperature SCR of NOx with ammonia. The effects of the calcination temperature of MAS support and Mn loading on catalyst structure and performance were examined. The Mn0.12/MAS-700 catalyst showed the best low-temperature denitrification performance, with more than 80% conversion of NO at 150–300 °C and higher than 60% N2 selectivity. Moreover, the denitrification efficiency remained at nearly 90% in the presence of H2O. The physicochemical properties of the catalysts were determined using various characterization methods, and the corresponding results found that the higher concentration of Mn4+ and surface chemisorption oxygen enhanced the low-temperature activity of the catalysts. The addition of Mn species increased the surface acidity of weak acid centers which promoted the catalyst activity. In situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) revealed that the Eley-Rideal mechanism was introduced mainly at 100 °C on the Mn0.12/MAS-700 catalyst. This work provides new inspiration into the effect of Mn species, and the synergistic role of active components Mn and MAS support in the SCR reaction.

Insights into the calcination temperature and loading amount of the catalyst support (TiO2) in the fibrous ceramic-based catalytic filter element prepared by microwave drying

The fibrous ceramic-based catalytic filter element (CFE) is a promising multifunctional material capable of simultaneously removing dust and NOx from hot gases. In this study, various calcination temperatures and titanium sols with different solid contents were used to prepare CFEs based on microwave drying, and their influences on the catalytic performance were experimentally investigated. The results showed that both the calcination temperature and the solid content of the titanium sol had important impacts on the catalytic activity. As the calcination temperature increased, the particle size, crystallite size, and average pore diameter of the loaded catalyst support (TiO2) increased, while the specific surface area decreased, ultimately resulting in a decline in the catalytic activity. However, a suitable calcination temperature ranging from 300 to 400 °C was required to achieve a good combination between the catalyst and the fibrous ceramic and a relatively uniform mesoporous structure. Furthermore, the increase in the solid content gave rise to a corresponding increase in the TiO2 loading amount, which increased the pressure drop and reaction surface area of the CFE. Excessive vanadium content caused by insufficient catalyst support induced side reactions of NH3 oxidation under high-temperature conditions, thereby reducing catalytic activity. Therefore, the preferred calcination temperature and solid content were set at approximately 300–400 °C and 8 wt%, respectively. The final prepared CFE demonstrated superior catalytic performance and adaptable gas velocity properties.

Efficient Hydrogenation of Methyl Palmitate to Hexadecanol over Cu/m-ZrO2 Catalysts: Synergistic Effect of Cu Species and Oxygen Vacancies

Renewable fatty esters are a class of clean feedstock to produce high value-added fatty alcohols. Herein, the hydrogenation of methyl palmitate (MP) to hexadecanol over defect-rich Cu/m-ZrO2 catalysts was studied systematically. A series of Cu/m-ZrO2 catalysts with different concentrations of oxygen vacancies (Ovs) were fabricated by adjusting the calcination temperature of m-ZrO2 support. Among the catalysts, Cu/m-ZrO2-350 displays the highest Cu dispersion, the largest number of Cu0 sites and surface Ov concentration, which exhibits the best activity for MP hydrogenation. It gives the MP conversion of 94.6% and hexadecanol yield of 93.3% at 300 °C and 7.5 MPa of H2. Spectroscopic characterizations and theoretical calculations revealed that the highly dispersed Cu species and abundant Ov sites synergistically boost the hydrogenation of MP. Specifically, the Cu0 sites facilitate the heterolysis of H2, and the Ov sites contribute to the dissociation of MP. The synergistic effect of Cu species and Ov sites disclosed in this work provides deep insights into the design of catalysts for efficient conversion of fatty esters to fatty alcohols.

Facile conversion of glycerol to 1,3-dihydroxyacetone by using mesoporous CuO–SnO2 composite oxide supported Au catalysts

Selective catalytic oxidation of polyols, e.g., the selective catalytic oxidation of the secondary –OH bond in glycerol, remains a considerable challenge. In this study, a series of mesoporous CuO–SnO2 composite oxides were prepared by a hard-template method and used to support Au catalysts for the selective oxidation of glycerol to 1,3-dihydroxyacetone (DHA) under base-free conditions. Catalysts with different Cu:Sn molar ratios gave different catalytic performances. A high conversion of glycerol (100%) and selectivity for DHA (94.7%) were obtained in 2 h at 80 °C and PO2 = 1 MPa over the Au/CuO–SnO2-3:1 catalyst. Further investigation indicated that the high catalytic activity of Au/CuO–SnO2-3:1 is related to the small size and high dispersion of Au nanoparticles (NPs), the interactions between the Au NPs and the support, the synergistic effect between CuO and SnO2, and the amount of surface lattice oxygen species. Various reaction parameters, namely the glycerol:Au molar ratio, the reaction temperature, the initial O2 pressure, the reaction time, and the support calcination temperature were studied. Although the conversion rate by the catalyst decreased after four cycles, the selectivity remained above 86%. Density functional theory calculations showed that the synergy between CuO and SnO2 improves the catalytic activity in glycerol oxidation to DHA. The results show that mesoporous composite oxide supports have a wide range of potential applications in the selective oxidation of glycerol to other high-value-added products.

The influence of phase purity on the stability of Pt/LaAlO3 catalysts in the aqueous phase reforming of glycerol

Aqueous phase reforming (APR) of waste oxygenates offers the potential for sustainable hydrogen production. However, catalyst stability remains elusive, due to the aggressive hydrothermal conditions employed. Herein, we show that the catalytic performance and stability of Pt supported on LaAlO3 catalysts for glycerol APR is strongly influenced by the phase purity of LaAlO3. Calcination of the support at 700 °C produces the LaAlO3 perovskite phase and an amorphous lanthanum carbonate phase, which can be removed by calcination at higher temperature. Catalysts comprised of phase pure LaAlO3 were notably more active, with a support calcination temperature of 1100 °C resulting in 20.4% glycerol conversion (TOF 686 h−1) in a 2 h batch reaction. Interestingly, all the catalysts, regardless of LaAlO3 phase purity, eventually transform into Pt/LaCO3OH-AlO(OH) during reaction, but only in the presence of evolved carbon dioxide, itself produced from glycerol reforming. Studies using simulated reaction products showed that organic acid products (lactic acid), in the absence of CO2, facilitated La leaching and loss of crystallinity. A carbonate source (CO2) is essential to limit La leaching and form stable Pt/LaCO3OH. Pt supported on LaCO3OH and AlO(OH) are stable and active catalysts during APR reactions. Yet, the rate of perovskite phase decomposition strongly influences the final catalyst performance, with the initially phase impure LaAlO3 decomposing too quickly to facilitate Pt redistribution. LaAlO3 calcined at higher temperatures evolved more slowly and consequently produced more active catalysts.

Selective production of guaiacol from lignin via catalytic transfer hydrogenolysis using Ru-Cu/Zirconia

In this study, the effect of calcination temperature of zirconia support (400, 600, and 800 °C) and the role of bimetallic Ru-Cu over monometallic (Cu, Ru) catalysts are evaluated for catalytic transfer hydrogenolysis of alkali lignin. The prepared catalysts were characterized extensively for crystallinity, pore size distribution, acidity, thermal stability and chemical oxidation state. The transformation of zirconia from non-crystalline to crystalline phase was observed with increasing calcination temperature. The pores transformed from wide ink bottle shape into cylindrical shape with increased calcination temperature. The XPS analysis revealed the existence of Cu0 (60%) in presence of Ru with a concomitant reduction in Ru4+ on the surface of the catalyst, which is attributed to increased crystallinity of zirconia in the presence of copper. High yields of total monomers (32.4 wt.%) and guaiacol (12.7 wt.%) were obtained under the optimized condition (270 °C, 3 h) with Ru-Cu/ZrO2 when ZrO2 was calcined at 800 °C. The mesoporous nature of zirconia and the strong metal-support interaction exhibited by Ru-Cu are shown to influence the formation of monomers. Increase in temperature from 225 to 270 °C enhanced the yield of guaiacol, 4-methyl guaiacol and 4-ethyl guaiacol with a concomitant reduction in the yield of trans-isoeugenol, demonstrating the cleavage of C–C bonds. The recyclability tests of the catalyst showed that the yield of guaiacol remained stable even after two cycles of catalyst reuse without calcination.

Formation of perovskite-type LaNiO3 on La-Ni/Al2O3-ZrO2 catalysts and their performance for CO methanation

The carbon deposition and sintering of Ni-based catalysts, used in CO methanation, are the main problems to be solved. In this paper, supported LaNiO3/Al2O3-ZrO2 catalyst was prepared by neutralization hydrolysis-citric acid complexation method. The effects of La-Ni loading and calcination temperature of support on the structure and catalytic activity of the catalyst were investigated. The structural evolution of catalyst precursor before and after reduction was studied via XRD, H2-TPR, BET, XPS, TEM and other characterization methods. The results showed that the catalyst supported by homogeneous Al-Zr solid solution was beneficial to form the active component with LaNiO3 structure, and the Ni0 derived from LaNiO3 was the key factor for keeping the activity at high temperature. The La-Ni loading affected the formation of LaNiO3 and the reduction state of Ni. Among the catalysts studied, 30% of the La-Ni loading was more favorable for the formation of perovskite LaNiO3. The Ni0 and La2O3 reduced from LaNiO3 were highly dispersed on the surface of the support, and the Ni0 nanoparticles were anchored by the support and La2O3, which inhibited the migration and aggregation of Ni0 particles at high temperature and thus led to high thermal stability.

Decoration of anatase-graphene nanocomposites on extruded nano-porous mullite based support for dye degradation under solar irradiation in a dynamic system: Photocatalytic activity and mechanical characterization

Abstract In spite of fundamental investigations about the preparation of anatase-graphene based photocatalysts for contaminant degradation, the photoreactor design for wastewater treatment under solar irradiation, still remained as unsolved which needs considering the facile decoration, mechanical reliability and economy. In the present work, anatase-graphene nanocomposites prepared with seven different procedures, were immobilized onto the mullite based ceramic supports fabricated by extrusion as rods and examined in wastewater recovery contaminated by cationic dye in the batch and dynamic system with rapid recirculation rate, 430 ml min−1, to ensure keeping the activity in the appropriate level. The factors affected the degradation yield included photocatalytic composite, titanium resource, support calcination temperature and wastewater circulation flow rate. It was shown that the TiO2-graphene oxide nanocomposite decorated onto the rods via aminopropyltrimethoxysilane, exhibits the appropriate activity, in comparison to that produced by anatase-reduced graphene oxide dip coating. The photocatalytic degradation was extremely improved, up to 90%, through the support calcination at 1100 °C in which the mullite was formed and pore size was distributed in the range of 10–100 nm. The screen of compressive strength data was performed by the normal and Weibull distributions to analyze the reliability of fabricated nano-porous mullite support. Based on the obtained statistical information, the calcination of support at mentioned temperature is proposed as a reliable condition to reinforce the ceramic rods, 10 MPa. The fabricated support not only is mechanically reliable but also is cost-effective, economically.

CO2 hydrogenation to methanol at high reaction temperatures over In2O3/ZrO2 catalysts: Influence of calcination temperatures of ZrO2 support

This work investigated the role of calcination temperatures (600, 700, 800, 900 and 1000 °C) of ZrO2 support on the physicochemical properties of In2O3/ZrO2 catalysts (denoted as 20In/Zr-X with X, calcination temperature of ZrO2 support) as well as their catalytic activity in CO2 hydrogenation to methanol at high reaction temperatures (320–400 °C). The calcination temperature played a crucial role on crystal structure of In2O3 and ZrO2, reducibility of In2O3 and adsorption-desorption of CO2 and H2. XRD analysis revealed that cubic In2O3 and amorphous ZrO2 were presented in 20In/Zr-600. With increasing calcination temperature of ZrO2 support from 600 to 1000 °C, the tetragonal ZrO2 was formed and the In2O3 and ZrO2 crystallite sizes were enlarged. The degree of In2O3 reduction was found to gradually decrease with increasing the calcination temperature of ZrO2 support due to the increase of In2O3 crystallite size. The adsorption strength of CO2 and H2 with the catalysts surface was found to be as follows: ZrO2 > 20In/Zr-1000 > 20In/Zr-900 > 20In/Zr-800 > 20In/Zr-700 > 20In/Zr600 > In2O3. The different calcination temperatures of ZrO2 support did not significantly affect the formation of CO but strongly dominated the yield of CH3OH and CH4. At reaction temperatures of 320–340 °C, the 20In/Zr-800 provided the maximum yield of CH3OH. However, as the reaction temperature was further increased, the maximum yield of CH3OH was obtained over the 20In/Zr-900, indicating that higher adsorption strength of CO2 and H2 enhanced the formation of CH3OH at higher reaction temperatures. Moreover, the strong interaction of H2 and CO2 with the catalysts surface suppressed the formation of CH4.

Deactivation of PdO-Alumina Catalysts Caused by SO2: The Effect of Support Calcination

This study focuses on the deactivation mechanisms for Pd/Al2O3 owing to SO2 poisoning. The impacts of support calcination temperature were elucidated. Results showed that the SO2 was converted firstly over PdO to SO3 under the oxidizing condition involving SO2. Then SO3 will transfer from PdO to the support only under the presence of surface hydroxyl groups, and sulfate was formed. And the relationship between the acidity of the catalysts and the poisoning effect of SO2 were discussed.

NO reduction by CO over CoOx/CeO2 catalysts: Effect of support calcination temperature on activity

CeO2 supported CoOx catalysts showed promising results in many NO reduction processes including NO reduction by CO. In this work, a series of CeO2 supports with different calcination temperatures (as received-800 °C calcination) were prepared, followed by the synthesis of a series of CoOx/CeO2 catalysts with a surface density of 2.5 Co/nm2 using the incipient wetness impregnation method. To understand the physicochemical properties of catalysts, various characterizations techniques, including BET, Raman spectroscopy, XRD, and H2-TPR, were performed. The results showed that as calcination temperature increased, physical properties of supporting materials were changed. Surface CoOx improved the reducibility of CeO2, but it was not affected by the support calcination temperatures confirmed by H2-TPR. The presence of CoOx was crucial to enhance the catalytic activity during the NO reduction by CO reaction, rather than physical properties (surface area, pore size, particle size) of the catalyst.

The effects of calcination temperature of support on Au/CuO-ZrO2 catalysts for oxidation of glycerol to dihydroxyacetone

Dihydroxyacetone (DHA) is a fine chemical and has been widely used in the cosmetics industry. In this work, DHA was synthesized with high selectivity over Au catalysts, also supported by Cu-Zr mixed oxide calcined at different temperatures. The effects of the calcination temperature of supports on the properties and catalytic performance for glycerol oxidation to dihydroxyacetone were also studied. BET and CO2-TPD measurements demonstrated that the increase in the support calcination temperature reduced the specific surface area of the catalyst and further reduced the surface basic sites of the catalysts. With increased support calcination temperature, the surface content of Au0 and the dispersion of Au first increase until the calcination temperature of the support was 600 °C and then decrease. It was also observed that the glycerol conversion is positively correlated with the surface content of Au0 and the dispersion of Au, while upon the increase of the amount of the basic sites, the catalytic activity increases first and then decreases. The suitable support calcination temperature is beneficial for the conversion of glycerol, and the best catalytic performance is obtained when the calcination temperature is 600 °C.

Efficient imine synthesis from oxidative coupling of alcohols and amines under air atmosphere catalysed by Zn-doped Al2O3 supported Au nanoparticles

Direct oxidative coupling of alcohols and amines is regarded as an effective and green approach for imine synthesis under mild conditions. In this work, Zn-doped γ-Al2O3 supported Au nanoparticles was demonstrated as highly active and selective heterogeneous catalyst for a series of imine productions with good to excellent yields, from alcohols and amines via direct oxidative coupling under air atmosphere without extra base additives. Various physicochemical techniques, including ICP-MS, XRD, N2 physisorption, TEM, XPS and CO2-/NH3-TPD, were used to study the properties of the catalysts. Well-dispersed Au0 nanoparticles with a mean size of ca. 2.9 nm were found highly effective in activating alcohols in the presence of reactive amines. The amount of Zn2+ dopant and the calcination temperature of support during catalyst preparation showed crucial impact on tuning the intrinsic activity for oxidation of benzyl alcohol to benzaldehyde (i.e., the rate-determining step for the model reaction), which was disclosed to be related with the active surface oxygen species and the acidic-basic property of support. The 0.4% Au/Zn0.02Al2O3 catalyst calcined at 400 °C exhibited the highest TOF (39.1 h−1) at 60 °C based on a >99% yield to benzylideneaniline among all the ever-reported Au-based catalysts. Moreover, this catalyst could afford 98% yield to benzylideneaniline at only 30 °C and work effectively for the gram-scale synthesis. It also showed considerable stability after five consecutive recycling.

Tuning performance of Pd/Sn0.9Ce0.1O2 catalyst for methane combustion by optimizing calcination temperature of support

A series of 0.2 wt% Pd/Sn0.9Ce0.1O2 catalysts were prepared by impregnation method based on the pre-synthesis of Sn0.9Ce0.1O2 support prepared by co-precipitation method, and then characterized by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, CO chemical adsorption and hydrogen temperature-programmed reduction (H2-TPR) techniques. The effect of calcination temperature of the composite oxide support on the catalytic performances of the Pd/Sn0.9Ce0.1O2 catalyst for the CH4 total oxidation was studied. It is found that the catalytic activity of the Pd/Sn0.9Ce0.1O2 catalyst increases with the increase in calcination temperature of the Pd/Sn0.9Ce0.1O2 support. The 0.2 wt% Pd/Sn0.9Ce0.1O2/1100 catalyst (the Pd/Sn0.9Ce0.1O2 support was calcined at 1100 °C) exhibits the best reactive activity (T10 = 255 °C). The excellent activity of the 0.2 wt% Pd/Sn0.9Ce0.1O2/1100 catalyst should be attributed to the high reducibility of PdO, the excellent oxygen mobility of the support and the high content of active Pd2+ species on the Pd/Sn0.9Ce0.1O2 catalyst.

Catalytic combustion of methane over Pd/SnO2 catalysts

SnO2-supported Pd catalysts were prepared and the effects of the support calcination temperature on the subsequent catalytic activity during methane combustion were investigated. The physicochemical properties of the Pd/SnO2 were characterized by X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, oxygen temperature-programmed desorption and CH4 temperature-programmed surface reaction. Only crystalline Pd species were found on the catalysts fabricated from the supports calcined above 800 °C. It was also determined that lattice geometry matching between PdO and SnO2 in the catalyst made with a support calcined at 1200 °C facilitated oxygen activation from SnO2 to vacant oxygen sites on the PdO/Pd surface via the back-spillover of oxygen. This effect in turn enhanced the catalytic combustion process. The activity of this material was clearly increased compared with the catalysts that did not exhibit lattice matching between the PdO and support.

Study of cobalt molybdenum oxide supported on mesoporous silica for liquid phase cyclohexane oxidation

Liquid phase oxidation of cyclohexane, by molecular oxygen, has been carried out using cobalt molybdenum oxide (CoMoO4) catalyst supported on mesoporous silica supports (SBA-15, KIT-6 and FDU-12). For each support, the catalyst activity has been studied as a function of loading, pore size, and calcination temperature. The catalysts were characterized using surface area analysis (BET), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Among the three supported catalysts, the one on FDU-12 shows the highest activity. The catalysts with lower loading, lower calcination temperature and lower pore size of support show higher activity but with lower selectivity. All the studied catalysts gave about 7–8% conversion, with selectivity of 85% for cyclohexanone and cyclohexanol (KA oil), before deactivation took over. The deactivated catalysts could be fully regenerated by re-calcination in every case. With such regeneration between runs, the catalysts are shown to retain their activity and selectivity over multiple cycles. The kinetic model which was proposed for the unsupported catalyst has been shown to work well for the supported catalysts as well.

The effects of calcination temperature of support on PtIn/Mg(Al)O catalysts for propane dehydrogenation reaction

The dehydrogenation of propane to propylene on bimetallic PtIn supported on calcined hydrotalcite, PtIn/Mg(Al)O-T, was investigated with the aim of understanding the effects of calcination temperature of hydrotalcite (MgAlO) on the structure/activity relationship of catalysts. The results showed that the highest catalysis reactivity and propylene selectivity were achieved over PtIn/Mg(Al)O-600 catalyst, which was improved obviously compared to our previous studies. The SEM images showed that all PtIn/Mg(Al)O-T catalysts had the flake structure collapsing constantly with the increasing calcination temperature of supports, which resulted in the change of textural properties of catalysts and the formation of more stable structure. Calcination temperature of support had obvious effect on the surface acid sites of PtIn/Mg(Al)O-T catalysts, and PtIn/Mg(Al)O-600 sample exhibited the lowest fraction of strong acid sites that were extremely unfavorable for facilitating propane dehydrogenation reaction. Besides, PtIn/Mg(Al)O-600 catalyst had the smallest average metal particle size as well as the largest specific surface area. XPS revealed that enhancing the interaction between indium and support was conductive to promoting the reduction of platinum. H2-TPR data suggested that the low-temperature reduction peak of PtIn/Mg(Al)O-600 was related to the unique catalytic behavior in the initial stage of propane dehydrogenation reaction. It can be concluded that PtIn/Mg(Al)O-600 catalyst possessed the largest surface area, the lowest fraction of strong acidic sites and In0 species, the best reducibility and distribution of Pt particles with the smallest Pt particle size, and the lowest coke amount corresponding to the best catalytic performance.