Graduate Program
Chemistry
Degree Name
Master of Science (MS)
Semester of Degree Completion
2011
Thesis Director
Jonathan Blitz
Thesis Committee Member
Doug Klarup
Thesis Committee Member
Barbara Lawrence
Abstract
Titania and titania-containing nanomaterials are semiconductor photocatalysts and are widely used to degrade (i.e. oxidize) organic matter. The adsorption and catalytic properties of highly dispersed titania prepared using sulfate and pyrogenic methods, and fumed containing mixed oxides, were studied using catalytic decomposition of methylene blue primarily by kinetic methods. Commercial ultrafine titania (PC-100, PC-105 and PC-500), fumed Ti 02, and the mixed oxide of 80% Silica/20% Titania (ST20) were studied. Catalytic activity as measured by methylene blue decomposition kinetics was highest per gram for non-treated ultrafine titania PC- 500 which has the highest SsET and smallest particle size. However this activity per m2 was higher for PC-105, having a smaller SsET value than PC-500. When it comes to activity per unit surface area of titania ST20 had the highest catalytic activity.
Heating of the titania affects the catalytic activity which was observed on PC-500. PC-500 heated at 650°C had higher catalytic activity than the titania heated at 800°C and 900 °C. This is due to the enhancement of anatase content at 650°C and rutile content at 800°C and 900 °C.
Aminosilanes are the most widely used organosilanes because of their wide range of applications and their use as precursors for the modification of silica surfaces. The choice of aminosilane and silica is essential for controlling their amount, stability and distribution on the surface of the silica. Comparison oftrialkoxy silanes between APTES and ABTES clearly indicate that increase in chain length in ABTES increases the catalyzing action in silica gels exception in pyrogenic silica. Aminosilanes with the same chain length but different number of hydrolysable groups show monoalkoxysilane APDMES having more flexibility than trialkoxysilanes APTES and AB TES to catalyze TMMS. When the number of amine groups increases in the aminosilane the chances of forming clumps or restricted movement increases as seen in AEIDMS in catalyzing TMMS.
Comparison among the silicas clearly indicates HS-5 composed of solid non-porous primary particles of approximately I 0nm was able to catalyze higher TMMS. Among the silica gels, 200DF given its narrow pore nature and cross-linking had least catalyzation of TMMS for trialkoxy silanes.
Recommended Citation
Samala, Ramkumar, "Catalytic activity of titania and titania-containing nanomaterials: And, Spatial distribution of silica surface groups using a tethered amine catalyst" (2011). Masters Theses. 81.
https://thekeep.eiu.edu/theses/81
