The Effect of Nitrogen Surface Ligands on Propane Metathesis: Design and Characterizations of N-modified SBA15-Supported Schrock-type Tungsten Alkylidyne

Handle URI:
http://hdl.handle.net/10754/316750
Title:
The Effect of Nitrogen Surface Ligands on Propane Metathesis: Design and Characterizations of N-modified SBA15-Supported Schrock-type Tungsten Alkylidyne
Authors:
Eid, Ahmed A.
Abstract:
Catalysis, which is primarily a molecular phenomenon, is an important field of chemistry because it requires the chemical conversion of molecules into other molecules. It also has an effect on many fields, including, but not limited to, industry, environment and life Science[1]. Surface Organometallic Chemistry is an effective methodology for Catalysis as it imports the concept and mechanism of organometallic chemistry, to surface science and heterogeneous catalysis. So, it bridges the gap between homogenous and heterogeneous catalysis[1]. The aim of the present research work is to study the effect of Nitrogen surface ligands on the activity of Alkane, Propane in particular, metathesis. Our approach is based on the preparation of selectively well-defined group (VI) transition metal complexes supported onto mesoporous materials, SBA15 and bearing amido and/or imido ligands. We choose nitrogen ligands because, according to the literature, they showed in some cases better catalytic properties in homogenous catalysis in comparison with their oxygen counterparts[2]. The first section covers the modification of a highly dehydroxylated SBA15 surface using a controlled ammonia treatment. These will result in the preparation of two kind of Nitrogen surface ligands: - One with vicinal silylamine/silanol, (≡SiNH2)(≡SiOH), noted [N,O]SBA15 and, - Another one with vicinal bis-silylamine moieties (≡SiNH2)2, noted [N,N]SBA15[3]. The second section covers the reaction of Schrock type Tungsten Carbyne [W(≡C- tBu)(CH2-tBu)3] with those N-surface ligands and their characterizations by FT-IR, multiple quantum solid state NMR (1H, 13C), elemental analysis and gas phase analysis. The third section covers the generation of the active site, tungsten hydride species. Their performance toward propane metathesis reaction using the dynamic reactor technique PID compared toward previous well-known catalysts supported on silica oxide or mesoporous materials[4]. A fairly good turn over number (TON = 43) has been obtained following hydrogen treatment of tungsten alkylidyne supported on [N,O] SBA151100, in comparison with TON of zero in the obtained with [N,N] SBA15 and classical SiO2 silica support. Therefore, the cooperation between silylamine and silanol in close vicinity are required to improve the efficiency of the catalyst in the metathesis of propane.
Advisors:
Basset, Jean-Marie ( 0000-0003-3166-8882 )
Committee Member:
Huang, Kuo-Wei ( 0000-0003-1900-2658 ) ; Sarathy, S. Mani
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Program:
Chemical Sciences
Issue Date:
Apr-2014
Type:
Thesis
Appears in Collections:
Theses; Physical Sciences and Engineering (PSE) Division; Chemical Science Program

Full metadata record

DC FieldValue Language
dc.contributor.advisorBasset, Jean-Marieen
dc.contributor.authorEid, Ahmed A.en
dc.date.accessioned2014-05-13T07:26:24Zen
dc.date.available2014-05-13T07:26:24Zen
dc.date.issued2014-04en
dc.identifier.urihttp://hdl.handle.net/10754/316750en
dc.description.abstractCatalysis, which is primarily a molecular phenomenon, is an important field of chemistry because it requires the chemical conversion of molecules into other molecules. It also has an effect on many fields, including, but not limited to, industry, environment and life Science[1]. Surface Organometallic Chemistry is an effective methodology for Catalysis as it imports the concept and mechanism of organometallic chemistry, to surface science and heterogeneous catalysis. So, it bridges the gap between homogenous and heterogeneous catalysis[1]. The aim of the present research work is to study the effect of Nitrogen surface ligands on the activity of Alkane, Propane in particular, metathesis. Our approach is based on the preparation of selectively well-defined group (VI) transition metal complexes supported onto mesoporous materials, SBA15 and bearing amido and/or imido ligands. We choose nitrogen ligands because, according to the literature, they showed in some cases better catalytic properties in homogenous catalysis in comparison with their oxygen counterparts[2]. The first section covers the modification of a highly dehydroxylated SBA15 surface using a controlled ammonia treatment. These will result in the preparation of two kind of Nitrogen surface ligands: - One with vicinal silylamine/silanol, (≡SiNH2)(≡SiOH), noted [N,O]SBA15 and, - Another one with vicinal bis-silylamine moieties (≡SiNH2)2, noted [N,N]SBA15[3]. The second section covers the reaction of Schrock type Tungsten Carbyne [W(≡C- tBu)(CH2-tBu)3] with those N-surface ligands and their characterizations by FT-IR, multiple quantum solid state NMR (1H, 13C), elemental analysis and gas phase analysis. The third section covers the generation of the active site, tungsten hydride species. Their performance toward propane metathesis reaction using the dynamic reactor technique PID compared toward previous well-known catalysts supported on silica oxide or mesoporous materials[4]. A fairly good turn over number (TON = 43) has been obtained following hydrogen treatment of tungsten alkylidyne supported on [N,O] SBA151100, in comparison with TON of zero in the obtained with [N,N] SBA15 and classical SiO2 silica support. Therefore, the cooperation between silylamine and silanol in close vicinity are required to improve the efficiency of the catalyst in the metathesis of propane.en
dc.language.isoenen
dc.subjectSurface organometallic chemistryen
dc.subjectCatalysisen
dc.subjectpropane metathesisen
dc.subjectnitrogen ligandsen
dc.subjecttungsten alkylidyneen
dc.subjectgraftingen
dc.titleThe Effect of Nitrogen Surface Ligands on Propane Metathesis: Design and Characterizations of N-modified SBA15-Supported Schrock-type Tungsten Alkylidyneen
dc.typeThesisen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberHuang, Kuo-Weien
dc.contributor.committeememberSarathy, S. Manien
thesis.degree.disciplineChemical Sciencesen
thesis.degree.nameMaster of Scienceen
dc.person.id124244en
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