Destekli tek ve çift metalli katalizörler üzerinde yapı ve aktivite tahminleri.

The purpose of this study is to simulate PtIB (IB=Ag, Au, Cu) and PtPd bimetallic catalysts with Monte Carlo method for 201, 586, 1289, and 2406 atom containing clusters in the temperature range between 2981000K. The simulations were based on a coordination-dependent potential model in which binary interaction parameters were used. The binary interaction parameters were determined from the available thermodynamic data and classical thermodynamics mixing rules. The equilibrium structure of the clusters was dictated as a perfect cubo-octohedral shape. In the first part of this study, PtIb bimetallics were modelled in order to test the Monte Carlo program against the previously published work. In the second part of the study, the surface composition of PtPd bimetallic catalysts as a function of temperature and cluster size were estimated in order to offer further insight to the catalytic activity for CO oxidation reaction. It was found that at low temperatures Pd segregation took place on the catalyst. The Monte Carlo predictions were in good agreement with the published experimental data on the surface compositions.M.S. - Master of Scienc

Enhancement of hydrogen storage capacity of multi-walled carbon nanotubes with palladium doping prepared through supercritical CO2 deposition method

Pd doped Multi-Walled Carbon Nanotubes were prepared via supercritical carbon dioxide deposition method in order to enhance the hydrogen uptake capacity of carbon nanotubes at ambient conditions. A new bipyridyl precursor that enables reduction at moderate conditions was used during preparation of the sample. Both XRD analyses and TEM images confirmed that average Pd nanoparticle size distribution was around 10 nm. Hydrogen adsorption and desorption experiments at room temperature with very low pressures (0 -0.133 bar) were conducted together with temperature programmed desorption (TPD) and reduction (TPR) experiments on undoped and doped materials to understand the complete hydrogen uptake profile of the materials. TPD experiments showed that Pd nanoparticles increased the hydrogen desorption activity at moderate temperatures around at 38 degrees C while for undoped materials it was determined around at 600 degrees C. Moreover, a drastic enhancement of hydrogen storage was recorded from 44 mu mol/g sample for undoped material to 737 mu mol/g sample for doped material through adsorption/desorption isotherms at room temperature. This enhancement, also verified by TPR, was attributed to spillover effect. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved

Enhancement of hydrogen storage capacity of multi-walled carbon nanotubes with palladium doping prepared through supercritical CO2 deposition method

Pd doped Multi-Walled Carbon Nanotubes were prepared via supercritical carbon dioxide deposition method in order to enhance the hydrogen uptake capacity of carbon nanotubes at ambient conditions. A new bipyridyl precursor that enables reduction at moderate conditions was used during preparation of the sample. Both XRD analyses and TEM images confirmed that average Pd nanoparticle size distribution was around 10 nm. Hydrogen adsorption and desorption experiments at room temperature with very low pressures (0 -0.133 bar) were conducted together with temperature programmed desorption (TPD) and reduction (TPR) experiments on undoped and doped materials to understand the complete hydrogen uptake profile of the materials. TPD experiments showed that Pd nanoparticles increased the hydrogen desorption activity at moderate temperatures around at 38 degrees C while for undoped materials it was determined around at 600 degrees C. Moreover, a drastic enhancement of hydrogen storage was recorded from 44 mu mol/g sample for undoped material to 737 mu mol/g sample for doped material through adsorption/desorption isotherms at room temperature. This enhancement, also verified by TPR, was attributed to spillover effect. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved