Synthesis, Characterization and in Situ Catalysis of Silica SBA-15 Supported Molybdenum Oxide Model Catalysts PDF Download
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Author: Jörg Thielemann
Publisher:
ISBN:
Category :
Languages : en
Pages : 169
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Author: Jörg Thielemann
Publisher:
ISBN:
Category :
Languages : en
Pages : 169
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Author: Nina Sharmen Genz
Publisher:
ISBN: 9783832549244
Category :
Languages : en
Pages : 257
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In this book, iron oxidic species supported on nanostructured silica (SBA-15) are introduced as model catalysts for deducing structure-activity correlations in selective oxidation of propene. Influence of iron loading, Fe(III) precursor, powder layer thickness during calcination, and molybdenum addition on structure and activity of Fe_{xO_{y/SBA-15 catalysts is investigated.Fe_{xO_{y/SBA-15 catalysts are characterized ex situ and in situ by a multitude of analyzing methods, i.e. XRD, DR-UV-Vis spectroscopy, N_{2physisorption, Raman and Mössbauer spectroscopy, GC-MS, X-ray absorption spectroscopy, and TPR. Moreover, applicability of solid-state kinetic analysis methods to supported iron oxidic species is shown. Results from solid-state kinetic analysis under non-isothermal conditions are particularly helpful in corroborating structure-activity correlations of Fe_{xO_{y/SBA-15 catalysts. Understanding the correlation of various synthesis parameters with structure and activity of Fe_{xO_{y/SBA-15 catalysts eventually permits obtaining improved green iron oxide catalysts for selective oxidation of propene.
Author: Rebecca Anne Shiels
Publisher:
ISBN:
Category : Catalysis
Languages : en
Pages :
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Book Description
Catalysis is an important field of study in chemical engineering and chemistry due to its application in a vast number of chemical transformations. Traditionally, catalysts have been developed as homogeneous molecular species or as heterogeneous insoluble materials. While homogeneous catalysts are typically very active and selective, they are difficult to recover. Conversely, heterogeneous catalysts are easy to recover and reuse, but they generally are less selective. To address these issues, the immobilization of homogeneous catalyst analogs onto solid supports has been a subject of research for the past few decades. Nonetheless, the effects of immobilization are still not completely predictable, and so continued effort is required to develop new immobilized catalysts as well as to develop a better understanding of how different parameters affect catalytic behavior. This dissertation presents the synthesis, characterization, and evaluation of new immobilized catalysts for different applications. First, a solid base catalyst supported on silica was developed and studied in the synthesis of cyclic carbonates from epoxides and carbon dioxide. Next, polymer and silica supported vanadium Schiff base catalysts were developed and evaluated for use in the oxidative kinetic resolution of alpha-hydroxy esters, an enantioselective reaction. Lastly, salen catalyst analogs with amine reactive functional groups were synthesized and characterized for grafting onto aminosilicas with different degrees of amine group isolation. The grafted catalysts were then tested to determine how catalyst spacing on the surface affects their behavior. Throughout the presentation of these results, comparisons are made amongst the new supported catalysts and relevant existing catalysts to discern general trends which could be applied to a wider range of immobilized catalysts. Finally, research opportunities for further improvements in these areas are suggested.
Author: Mohamad Irsyad Mohamad Mazuki
Publisher:
ISBN:
Category : Catalysis
Languages : en
Pages : 43
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Book Description
The research was about the synthesis of active and selective for syngas processing via Fischer-Tropsch synthesis (FTS) producing clean and best fuel. A series of 20 wt. % cobalt catalysts be prepared by impregnation of a mesoporous molecular sieve based on silica as 75 wt. % of cobalt catalytic supporters (SBA-15, TiO and CabO-Sil) with 5 wt. % Zn promoter for comparison purposes. All materials used characterizing by several analysis equipments which are SEM, TGA and FTIR. The characterization results achieve gave a great influence of mesoporous support porosity on the structure, reducibility of cobalt oxide species supported over the selected materials. Firstly, the experiment was started from the synthesis of SBA-15. TiO2 and Cab-O-Sil are commercialized support. Then, the silica as cobalt supporters were synthesized by incipient wetness impregnation method of using mixture of Cobalt (II) Nitrate and Zinc Nitrate Hexahydrate solution. Next, the prepared catalysts were calcined at 350°C for 6 h by increasing the temperature at a controlled heating rate of 2°C/min. The characterization of catalysts and catalyst studies was performed. The result from experiment was SBA-15 supporter shown the better result compared to other samples as the microscopic size captured by SEM equipment prove that SBA-15 had smoothest and smallest of mesoporous surface size. The result from FTIR showed that the peak at around 3,440 cm-1 have the hydroxyl groups and about 1,630 cm -12 is due to the bending vibrations of O-H bonds that the percentage reflectance of O-H bonds which indicates the SBA-15 can effectively restrain the loss of surface hydroxyl groups during calcinations. The peak around 1000-1200 cm1 can be assigned to the siloxane or Si-O-Si stretching bands; peak appears as a broad and strong peaking the sample. Lastly, TGA result showed that SBA-15 can help the catalyst samples restrained more water content in the evaporation process and had high thermal stability that can prolong life at high temperature and high pressure in the Fischer-Tropsch synthesis. The new silica as cobalt supporter will be developed to enhance the performance of the best and clean fuel production. This research hopefully can be carried out successful in order to get the new invention for production of catalyst that will produce the best and clean fuel and to get rid of exceed cost of production but in the same quality of expensive product.
Author: Marek Kosmulski
Publisher: CRC Press
ISBN: 142005189X
Category : Science
Languages : en
Pages : 1094
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Book Description
The Most Detailed Resource Available on Points of Zero ChargeWith their work growing in complexity, chemists involved with surface phenomena-related projects have outgrown the common resources available to them on points of zero charge (PZC) of oxides. Reporting on a limited number of materials in a limited number of scenarios, these resources ofte
Author: Anas Mohd Naim
Publisher:
ISBN:
Category : Catalysis
Languages : en
Pages : 48
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Book Description
Fischer-Tropsch synthesis (FTS) is one of the most promising ways for the conversion of syngas to hydrocarbon products. Supported cobalt is the preferred catalyst for FTS due to its high selectivity to heavy hydrocarbons, low activity for water-gas-shift reaction and comparatively low price. Cobalt loaded SBA-15 catalysts were prepared by two different techniques including wetness impregnation and direct-synthesis methods. The characterization of the synthesized samples was done by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2 adsorption-desorption,. XRD measurements showed that the calcined cobalt catalyst did not modify the structure of SBA-15, proving that Co was present under the form of Co3O4 in the catalyst. The hexagonal structure of pores of SBA-15 was confirmed by SEM images for all samples.BET surface area showed that Co/SBA-15 catalyst prepared by direct synthesis method was produced high surface area and pore volume compared prepared by wetness impregnation method.
Author: Mohd Ridzuan Azis
Publisher:
ISBN:
Category : Catalysts
Languages : en
Pages : 49
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Book Description
The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions.The increasing concentrations of the greenhouse gases in the atmosphere, where the major contribution comes from carbon dioxide (CO2). The result from a continued increase in CO2 concentration will cause major changes in global climate .Due to high concentration of CO2 in the environment, advanced oxidation process (AOP) was proposed. AOP is a process in which the oxidative capacity of a parent compound is modified to make oxidation-reduction reactions more rapid or complete. Due to the best properties that it can retain at high themperature and thermal stability SBA-15 has been chosen as catalysts. SBA-15 and Cu supported mesoporous siliceous SBA-15catalysts have been prepared by direct synthesis methods and wetness impregnation method, respectively and are systematically characterized. The characterizations of the synthesized samples were done using Fourier Transforms Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermal Gravimetric analysis (TGA) and X-ray diffraction (XRD). The FTIR analysis shows that when SBA-15 was doped with copper, the % transmittance of the spectral had decreased. From the SEM analysis, the surface morphology of SBA-15 was changed from smooth to course and irregular structure due to existence of Cu in SBA-15. XRD measurement shows that the amorphous phase for pure SBA-15 was changed to crystalline phase when Cu was deposited into SBA-15 proving that Cu present in the SBA-15 structure. The TGA analysis shows that with existence of Cu in SBA-15, enhanced the thermal stability properties of catalysts. Thermo gravimetric analysis shows that the copper deposition on SBA-15 is stable up to a temperature of 515 °C and that the copper decomposes between 515 °C and 798 °C. The results of the FTIR, SEM, XRD and TGA testify completely that the Cu was incorporated into the framework sites of the SBA-15.
Author: Mure Te
Publisher:
ISBN:
Category : Catalysis
Languages : en
Pages : 412
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Author: Pablo Beato
Publisher:
ISBN:
Category :
Languages : en
Pages : 106
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Author: Gregor Koch
Publisher: Logos Verlag Berlin
ISBN: 9783832541316
Category : Metal catalysts
Languages : en
Pages : 0
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Book Description
In this book, the Cu/SBA-15 model catalyst for methanol steam reforming is described in detail. This study is an exemplarily road map for investigating model catalysts. The mesoporous structure of SBA-15 support, the structure of supported copper nanoparticles and their activity with regard to H2 production are presented. Based on that, structure activity correlations are deduced. Moreover, relationships between the structure of precursors and the structure of active catalysts are deduced. Therefore several analytical are presented: N2 Physisorption, DR-UV/Vis, in situ XANES, TPR, in situ XRD, specific copper surface area (N2O), size and strain analysis of copper nanoparticles, H2 production by methanol steam reforming.The reliable analysis procedure of each experimental method is described and can be principally employed on similarly constructed catalysts.
