Preparation of mesoporous Ti - Organosilicate epoxidation catalysts, 2008
Mehreteab, Tesfamariam
2000-2009
Following the methodology used in solgel chemistry to functionalize amorphous silica, organic functionalized mesoporous silica were prepared by the co-condensation of tetraethoxysilane and organoalkoxysilanes in the presence of surfactant templates. A series of titanium catalysts containing Ti-MCM-41 with different bridging and pendant organic functional groups (such as methyl triethoxysilane (MTEOS), phenyl triethoxysilane (PTEOS), diphenyl triethoxysilane (DPTEOS), bis (triethoxysilyl) ethane (BTSE), 1,4 bis(triethoxysiyl) benzene (BTSB), bis( triethoxysilyl) biphenyl (BTSDP) and two catalysts with different organic-inorganic ratios (90% TEOS with 10% phenyl, 70% TEOS with 30% phenyl) were synthesized. The catalysts were characterized by elemental analysis, XRD, FTIR, UVDRS, by solid state 13C and 29Si MAS NMR, and BET surface area analysis. The catalytic activities of the synthesized materials were evaluated for epoxidation of cyclohexene with TBIIP. The materials yielded improved conversion compared to the conversion results obtained from the traditional titanium containing mesoporous silica (Ti-MCM-41). The hydrophobic character of the synthesized catalysts was tested in the epoxidation of cyclohexene by using wet TBIIP. Ti-MCM41 with bridged organosilane showed almost the same conversion in the presence of water, while for Ti-MCM-41 with organosilane pendant groups. conversion decreased almost 36%. This implies that the silylation of the surface ofTi-MCM4I protected the active sites. The effect of substrate: oxidant molar ratio in these reactions were studied and high conversion, high selectivity were achieved at 1:1 molar ratio.
text
application/pdf
2008-12-01
thesis
Master of Science (MS)
Clark Atlanta University
School of Arts and Sciences, Department of Chemistry
Ingram, Conrad W. Harruna, Issifu L. Parker, Cass D.
Georgia--Atlanta
http://hdl.handle.net/20.500.12322/cau.td:2009_mehreteab_tesfamariam
