Modyfikowane krzemionki, metalokrzemiany i tlenki metali – preparatyka, charakterystyka i zastosowanie w procesie estryfikacji z udziałem glicerolu
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Date
2014-05-21
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Modified silica, metallosilicates and metal oxides – preparation, characterization and application in the esterification process in the presence of glycerol
Abstract
Rozprawa doktorska wpisuje się w nurt badań dotyczących syntezy katalizatorów o właściwościach kwasowych, wykorzystywanych do reakcji prowadzonych w fazie ciekłej, np. estryfikacji. W ramach pracy doktorskiej otrzymano materiały bazujące na mezoporowatych piankach komórkowych (MCF) i mezoporowatych tlenkach Nb2O5 i NbxWyOz. Materiały MCF zmodyfikowano jednoetapowo lub posyntezowo prekursorami Nb, Ta, Al, Zr, Cu i P i/lub MPTMS ((3-merkaptopropylo)trimetoksysilanem) z udziałem H2O2 jako utleniacza, a tlenki zmodyfikowano posyntezowo P i/lub MPTMS. Wykonano także monitoring in-situ syntez MCF modyfikowanych metalami i MPTMS. Otrzymane katalizatory poddano charakterystyce tekstury/struktury, badaniom właściwości powierzchni oraz składu chemicznego i testom katalitycznym. Dodanie Nb i Ta podczas syntezy MCF prowadzi do utlenienia grup –SH w MPTMS, co umożliwia otrzymanie licznych grup –SO3H, wykazujących silną kwasowość Brønsteda (BAS). Metale te ponadto stabilizują zakotwiczoną fazę organiczną. Stabilizacja jest większa gdy MPTMS jest zakotwiczony w trakcie syntezy. Dodatkowe centra BAS powstają w obecności P wprowadzonego podczas impregnacji. Silne oddziaływanie Nb2O5 z H2O2 uniemożliwia zakotwiczenie dużych ilości MPTMS. Uzyskane w pracy wyniki umożliwiają określenie optymalnego doboru nośnika i modyfikatorów do otrzymania katalizatora aktywnego i selektywnego w estryfikacji.
The doctoral dissertation concerns the area of research on the synthesis of catalysts of acidic properties, used in the reactions in liquid phase, e.g. the reactions of esterification. Such catalysts synthesised in the doctoral studies were those based on mesoporous cellular foams (MCF) and those based on mesoporous oxides Nb2O5 and NbxWyOz. MCF - based materials were modified by one-pot procedure or post synthesis method with Nb, Ta, Al, Zr, Cu and P and/or MPTMS ((3-mercaptopropyl)trimethoxysilane) in the presence of H2O2 as oxidant, and the oxides were modified with P and/or MPTMS by post synthesis procedure. The synthesis of MCF modified with metals and MPTMS was monitored in situ. The textural/structural parameters, surface properties, chemical composition and catalytic activities of the catalyst obtained were determined. Nb and Ta addition during the MCF synthesis leads to the oxidation of –SH species, which allows generation of a high number of –SO3H species exhibiting strong Brønsted acidity (BAS). These metals stabilize also the anchored organic phase. This stabilization is stronger when MPTMS is anchored during the synthesis. Additional BAS centres are generated in the presence of P introduced during impregnation. Strong interaction of Nb2O5 with H2O2 prevents the anchoring of great amount of MPTMS. Results obtained in the study allow the optimal selection of support and modifiers to get active and selective catalyst for esterification.
The doctoral dissertation concerns the area of research on the synthesis of catalysts of acidic properties, used in the reactions in liquid phase, e.g. the reactions of esterification. Such catalysts synthesised in the doctoral studies were those based on mesoporous cellular foams (MCF) and those based on mesoporous oxides Nb2O5 and NbxWyOz. MCF - based materials were modified by one-pot procedure or post synthesis method with Nb, Ta, Al, Zr, Cu and P and/or MPTMS ((3-mercaptopropyl)trimethoxysilane) in the presence of H2O2 as oxidant, and the oxides were modified with P and/or MPTMS by post synthesis procedure. The synthesis of MCF modified with metals and MPTMS was monitored in situ. The textural/structural parameters, surface properties, chemical composition and catalytic activities of the catalyst obtained were determined. Nb and Ta addition during the MCF synthesis leads to the oxidation of –SH species, which allows generation of a high number of –SO3H species exhibiting strong Brønsted acidity (BAS). These metals stabilize also the anchored organic phase. This stabilization is stronger when MPTMS is anchored during the synthesis. Additional BAS centres are generated in the presence of P introduced during impregnation. Strong interaction of Nb2O5 with H2O2 prevents the anchoring of great amount of MPTMS. Results obtained in the study allow the optimal selection of support and modifiers to get active and selective catalyst for esterification.
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Wydział Chemii: Zakład Katalizy Heterogenicznej
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Keywords
kataliza, C\catalysis, MCF, tlenki metali, metal oxides, MPTMS, glicerol, glycerol