Ernam, Selin
The objective of this thesis is to investigate the bottlenecks of photocatalytic NO oxidation reaction. This reaction is used as a standard diagnostic tool for photocatalytic activity according to the well defined protocols described by the ISO Standard (22197-1-2007). One of the problems with photocatalytic NO oxidation is the transient period of NO conversion between the beginning of illumination and the time the conversions reach a steady state. The nature of this behavior depends strongly on parameters such as the illumination intensity and the concentration of the reactants, in particular the moisture content. In order to reveal the effect of the illumination intensity and the moisture content, devices with sensors and microcontroller boards were built. Controlled experiments revealed that at higher light intensities, the reaction starts with a very high conversion and need longer times to reach steady state, at a lower conversion value. In contrast, experiments with low light intensities reach this steady conversion level almost immediately after the reaction starts. Using the light intensity measurement device built for this purpose, a relationship was obtained between the steady state reactant conversion and illumination intensity (at 365 nm) as follows: X=c+aI^b where a=0.1809, b=0.3733, c=0.7265. Furthermore, the effect of water injections to the system was also investigated using a relative humidity measurement device specifically built for this purpose. The water injection transient data collected in this study revealed the qualitative nature of the interactions. The system can be effective at collecting data and can be used to determine a reaction model.


The deactivation behavior of the TiO2 used as a photo-catalyst for benzene oxidation
Üner, Deniz (1999-01-01)
In this study, the deactivation behavior of TiO2 as a photocatalyst for benzene decomposition to carbon dioxide and water was investigated. The effect of space time on the benzene and carbon dioxide conversions were monitored. Benzene conversion and carbon dioxide production rates were not correlated, indicating accumulation of a carbon containing intermediate on the surface. This intermediate was blocking the active sites at a stiochiometry of 1 C:1 site. High space times favored the production of carbon d...
Investigation of glucose electrooxidation mechanism over N-modified metal-doped graphene electrode by density functional theory approach
Duzenli, Derya; Önal, Işık; Tezsevin, Ilker (2022-10-01)
In this work, various precious and non-precious metals reported in the literature as the most effective catalysts for glucose electrooxidation reaction were investigated by the density functional theory (DFT) approach in order to reveal the mechanisms taking place over the catalysts in the fuel cell. The use of a single-atom catalyst model was adopted by insertion of one Au, Cu, Ni, Pd, Pt, and Zn metal atom on the pyridinic N atoms doped graphene surface (NG). beta form of d-glucose in alkaline solution wa...
Preparation and characterization of nanocomposites with a thermoplastic matrix and spherical reinforcement
Ersu, Dilek; Yılmazer, Ülkü; Department of Chemical Engineering (2006)
The aim of this study is to investigate the effects of compatibilizers, fumed silica and mixing order of components on morphological, thermal, mechanical and flow properties of LDPE/Fumed silica nanocomposites. As compatibilizer(Co); ethylene/n-butyl acrylate/maleic anhydride (E-nBA-MAH), ethylene/glycidyl methacrylate (E-GMA) and ethylene/methyl acrylate/glycidyl methacrylate (E-MA-GMA) Lotader® resins; as silica Cab-o-sil® M5 fumed silica were used. All samples were prepared by means of a lab scale co-rot...
Altun, Naci Emre; Kök, Mustafa Verşan (Springer Science and Business Media LLC, 2008-10-01)
This research presents the combustion behavior of lignite under different reaction pressures. Lignite from Alpagut, Corum of Turkey was combusted in its run off mine (ROM) condition under three different pressure levels of 172, 345, 517 kPa (25, 50, 75 psi). Experiments were done in a fully controlled temperature regime in an isolated combustion tube that operated in coordination with a continuous gas analyzer. Combustion behavior of lignite under different pressures was characterized by effluent gas analys...
Numerical investigations on the hydrogen jet pressure variations in a strut based scramjet combustor
Suppandipillai, Jeyakumar; Kandasamy, Jayaraman; Sivakumar, R.; Karaca, Mehmet; Karthik, K. (2021-04-01)
Purpose – This paper aims to study the influences of hydrogen jet pressure on flow features of a strut-based injector in a scramjet combustor underreacting cases are numerically investigated in this study. Design/methodology/approach – The numerical analysis is carried out using Reynolds Averaged Navier Stokes (RANS) equations with the Shear Stress Transport k-v turbulence model in contention to comprehend the flow physics during scramjet combustion. The three major parameters such as the shock wave pattern...
Citation Formats
S. Ernam, “INVESTIGATION OF THE TRANSIENT BEHAVIORS OF PHOTOCATALYTIC NO OXIDATION OVER TiO2,” M.S. - Master of Science, Middle East Technical University, 2022.