Characterization of combustion synthesized zirconia powder by UV-vis, IR and other techniques
TL;DR: In this article, fine powders of zirconia were prepared by employing combustion method with varying fuel to pre-cursor molar ratios, and the catalytic activity was probed with transfer hydrogenation reaction in liquid phase.
Abstract: Fine powders of zirconia were prepared by employing combustion method with varying fuel to pre-cursor molar ratios. The zirconia powders contained more amount of monoclinic phase as the fuel content was increased. This aspect was studied using XRD, IR and UV-vis diffuse reflectance techniques. The surface acid-base properties of these samples were also investigated by indicator titration method. The catalytic activity was probed with transfer hydrogenation reaction in liquid phase. It was found that combustion synthesized zirconia did not provide required active sites for transfer hydrogenation reactions in liquid phase unlike hydrous zirconia.
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TL;DR: A series of ceria-incorporated zirconia (Ce1−xZrxO2,x = 0 to 1) solid solutions were prepared by employing the solution combustion synthesis route as discussed by the authors.
Abstract: A series of ceria-incorporated zirconia (Ce1−xZrxO2,x = 0 to 1) solid solutions were prepared by employing the solution combustion synthesis route. The products were characterized by XRD and UV-Vis-NIR diffuse reflectance spectroscopy. The materials are crystalline in nature and the lattice parameters of the solid solution series follow Vegard’s law. Diffuse reflectance spectra of the solid solutions in the UV region show two intense bands at 250 and 297 nm which are assigned respectively to Ce3+ ← O2−and Ce4+ ← O2− charge transfer transitions. The two vibrational bands in 6960 cm−1 and 5168 cm−1 in the NIR region indicate the presence of surface hydroxyl groups on these materials.
149 citations
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TL;DR: In this paper, high-temperature stable three-dimensional spongelike mesoporous Ce x Zr 1− x O 2 solid solutions consisting of nanometer size particles with different Ce/Zr compositions were synthesized by a modified sol-gel procedure using a triethanolamine/water mixture as a solvent to be used in liquid Knoevenagel condensation reaction.
Abstract: Highly thermally stable three-dimensional spongelike mesoporous Ce x Zr 1− x O 2 solid solutions consisting of nanometer size particles with different Ce/Zr compositions were synthesized by a modified sol–gel procedure using a triethanolamine/water mixture as a solvent to be used in liquid Knoevenagel condensation reaction. These materials were investigated in detail by means of X-ray diffraction (XRD), Raman spectroscopy, chemical analysis, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and adsorption microcalorimetry. The XRD, HRTEM and XPS studies proved the presence of nanocrystalline Ce x Zr 1− x O 2 solid solutions. These solid solutions showed excellent chemoselectivity in the classical Knoevenagel reaction. The large pore sizes (around 10 nm) highlight the possibility of using Ce x Zr 1− x O 2 as a support material for versatile catalytic systems. The results obtained from NH 3 and SO 2 adsorption microcalorimetry experiments successfully demonstrated the incorporation of ZrO 2 into the CeO 2 lattice resulting in both acidic and basic surface sites in a mixed oxide matrix.
149 citations
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TL;DR: In this article, a 12-Tungstophosphoric acid anchored to SBA-15 was synthesized and characterized by various physico-chemical techniques such as TGA, FT-IR, DRS, XRD, N 2 adsorption-desorption, solid state NMR (31 P and 29 Si), SEM and TEM.
Abstract: 12-Tungstophosphoric acid anchored to SBA-15 was synthesized and characterized by various physico-chemical techniques such as TGA, FT-IR, DRS, XRD, N 2 adsorption–desorption, solid state NMR ( 31 P and 29 Si), SEM and TEM. The use of synthesized catalyst was explored for biodiesel production by esterification of free fatty acid, oleic acid with methanol. Influence of various reaction parameters (such as catalyst concentration, acid/alcohol molar ratio and reaction temperature) on catalytic performance was studied. The catalyst shows high activity in terms of conversion of oleic acid as well as high turnover frequency of 9.3 min −1 . It also shows potential of being used as recyclable catalyst material after simple regeneration. Kinetic investigation reveals that the esterification reaction of oleic acid with methanol follows a first order dependency on the concentration of the oleic acid and the catalyst. The influence of temperature on rate constant was also studied and the activation energy was found to be 44.6 kJ mol −1 . As an application, preliminary study was carried out for biodiesel production from waste cooking oil, as feedstock without any pre-treatment, with methanol. Studies show that the catalyst can be used for biodiesel production from waste cooking oil under mild conditions.
142 citations
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TL;DR: In this paper, a template-free synthesis of pure and Co-doped ZrO2 tetragonal structured nanoparticles was achieved by the hydrothermal method and their photocatalytic, photoelectrocatalytic and electrochemical energy storage supercapacitive properties were investigated for the first time.
Abstract: Template-free synthesis of pure and Co-doped ZrO2 tetragonal structured nanoparticles was achieved by the hydrothermal method and their photocatalytic, photoelectrocatalytic, and electrochemical energy storage supercapacitive properties were investigated for the first time. XRD revealed tetragonal crystal structure, while BET surface analysis suggested that Co-doped ZrO2 has higher surface area (186.4 m2g−1) than that of the undoped sample (99.5 m2g−1). The band gap value was reduced from 4.95 to 2.12 eV due to incorporation of cobalt. Under visible-light illumination, photocatalytic and photoelectrocatalytic activities for methyl orange (MO) dye degradation were evaluated. The working electrodes have been prepared with 85 wt% active material (pure and doped ZrO2), 10 wt% active carbon black, and 5 wt% polyvinylidene difluoride (PVDF) in order to perform the supercapacitive properties. The Co-doped ZrO2 material exhibited 93.7% and 27.4% MO dye degradation within 100 min with the highest specific capacitance value of 2151.2 Fg-1.
104 citations
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TL;DR: In this article, the use of synthesized catalyst was explored for biodiesel production by esterification of (free fatty acid) oleic acid with methanol, and the influence of various reaction parameters (catalyst concentration, acid/alcohol molar ratio, catalyst amount, reaction temperature and reaction time) on catalytic performance was studied to optimize the conditions for maximum yield of methyl oleate.
Abstract: Sulfated zirconia was synthesized and characterized by various physico-chemical techniques such as EDS, Thermal analysis (TGA & DTG), FT-IR, XRD, BET surface area measurement, SEM and n-butyl amine acidity determination. The use of synthesized catalyst was explored for biodiesel production by esterification of (free fatty acid) oleic acid with methanol. Influence of various reaction parameters (catalyst concentration, acid/alcohol molar ratio, catalyst amount, reaction temperature and reaction time) on catalytic performance was studied to optimize the conditions for maximum yield of methyl oleate. Also the catalyst was regenerated and reused. As an application, preliminary study was carried out for biodiesel production by transesterification of waste cooking oil and Jatropha oil, as feedstock without any pretreatment, with methanol.
95 citations
References
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TL;DR: CRC handbook of chemistry and physics, CRC Handbook of Chemistry and Physics, CRC handbook as discussed by the authors, CRC Handbook for Chemistry and Physiology, CRC Handbook for Physics,
Abstract: CRC handbook of chemistry and physics , CRC handbook of chemistry and physics , کتابخانه مرکزی دانشگاه علوم پزشکی تهران
51,056 citations
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TL;DR: A survey of the use of cerium oxide and CeO2-containing materials as oxidation and reduction catalysts is presented in this paper, with a special focus on catalytic interaction with small molecules such as hydrogen, carbon monoxide, oxygen, and nitric oxide.
Abstract: Over the past several years, cerium oxide and CeO2-containing materials have come under intense scrutiny as catalysts and as structural and electronic promoters of heterogeneous catalytic reactions. Recent developments regarding the characterization of ceria and CeO2-containing catalysts are critically reviewed with a special focus towards catalyst interaction with small molecules such as hydrogen, carbon monoxide, oxygen, and nitric oxide. Relevant catalytic and technological applications such as the use of ceria in automotive exhaust emission control and in the formulation of SO x reduction catalysts is described. A survey of the use of CeO2-containing materials as oxidation and reduction catalysts is also presented.
2,850 citations
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TL;DR: In this paper, the use of CeO 2 -based materials in the automotive three-way catalysts (TWCs) is considered, and the multiple roles of COO 2 as a TWC promoter and in particular the oxygen storage/release capacity (OSC) are critically discussed.
Abstract: In the present paper the use of CeO 2 -based materials in the automotive three-way catalysts (TWCs) is considered. The multiple roles of CeO 2 as a TWC promoter and in particular the oxygen storage/release capacity (OSC) are critically discussed. Attention is focused on the advanced OSC materials containing ZrO 2 , which are employed in the last generation of catalytic automotive converters.
1,555 citations
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TL;DR: In contrast to these extensive studies of heterogeneous acidic catalysts, fewer efforts have been given to the study of heterogenous basic catalysts as mentioned in this paper. But these studies have been continuous and progressed steadily, and they have never been reviewed in the chemical Reviews before.
Abstract: Heterogeneous acid catalysis attracted much attention primarily because heterogeneous acidic catalysts act as catalysts in petroleum refinery and are known as a main catalyst in the cracking process which is the largest process among the industrial chemical processes. In contrast to these extensive studies of heterogeneous acidic catalysts, fewer efforts have been given to the study of heterogeneous basic catalysts. The types of heterogeneous basic catalysts are listed in Table 1. Except for non-oxide catalysts, the basic sites are believed to be surface O atoms. The studies of heterogeneous catalysis have been continuous and progressed steadily. They have never been reviewed in the chemical Reviews before. It is more useful and informative to describe the studies of heterogeneous basic catalysis performed for a long period. In the present article, therefore, the cited papers are not restricted to those published recently, but include those published for the last 25 years. The paper first describes the generation of basic sites before describing methods used in the characterization of basic surfaces. These are indicator methods, temperature programmed desorption (TPD) of CO{sub 2}, UV absorption and luminescence spectroscopies, TPD of H{sub 2}, XPS, IR of CO{sub 2}, IR of pyrrole, and oxygen exchange betweenmore » CO{sub 2} and the surface. The paper then discusses studies on the catalysis by heterogeneous basic catalysts. Some of these reactions are dehydration, dehydrogenation, hydrogenation, amination, alkylation, ring transformation, and reactions of organosilanes. Catalysts discussed are single component metal oxides, zeolites, non-oxide types, and superbasic catalysts. 141 refs.« less
882 citations
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TL;DR: In this paper, a review article deals with recent progress in the preparation of sulfated zirconia (SZ)-bassed, strong solid-acid catalysts, the characterization of their physicochemical properties and the evaluation of their catalytic performance in various promising applications.
Abstract: This review article deals with recent progress in the preparation of sulfated zirconia (SZ)-bassed, strong solid-acid catalysts, the characterization of their physicochemical properties and the evaluation of their catalytic performance in various promising applications. Strong emphasis was put on discussion of controversial issues such as the strength of acid sites, the nature of active sites, the reaction mechanism, and the role and state of supported platinum. An important part of this work was devoted to recent catalytic applications.
603 citations
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