A dft study of ethylene adsorption and hydrogenation mechanisms on nickel

Download

index.pdf

Date

2010

Author

Yılmazer, Nusret Duygu

Metadata

Show full item record

Item Usage Stats

214
views

97
downloads

Ethylene adsorption was studied by use of DFT/B3LYP with basis set 6-31G(d,p) in Gaussian‘03 software. It was found that ethylene adsorbs molecularly on the Ni13 nanocluster with π adsorption mode. π adsorption mode is studied for the Ni10 (1 1 1), Ni13 (1 0 0) and Ni10 (1 1 0) surface cluster as well. Relative energy values were calculated as −50.86 kcal/mol, −20.48 kcal/mol, −32.44 kcal/mol and −39.27 kcal/mol for Ni13 nanocluster, Ni10 (1 1 1), Ni13 (1 0 0) and Ni10 (1 1 0) surface cluster models, respectively. Ethylene adsorption energy was found inversely proportional to Ni coordination number when Ni10 (1 1 1), Ni13 (1 0 0) and Ni10 (1 1 0) cluster models and Ni13 nanocluster were compared with each other. DFT/B3LYP and basis set of 86-411(41d)G in Gaussian‘03 was used to investigate Ni55 nanocluster. Ethylene adsorption on Ni55 nanocluster was studied by means of equilibrium geometry calculations with π adsorption modes for two different coordination numbers as 6 and 8. The related adsorption energies were approximately found as -22.07 and -14.82 kcal/mol for these coordination numbers of surfaces, respectively. In addition, the binding energies stated in literature that are for Ni2 dimer and Ni13 nanoclusters were considered together with our binding energy results for Ni55 nanocluster. Accordingly, when a correlation line was drawn and the intercept of binding energies was obtained against the value of ―n−1/3‖ ;where n is the number of atoms in the cluster; the result of interception gives a good estimation for bulk nickel binding energy at infinite ―n‖. This interception result was found as 4.58 eV/atom where the experimental value is reported as 4.45 eV/atom for bulk in the literature. Ehtylene hydrogenation mechanisms were also investigated in terms of the resultant geometries and total energy required for the related mechanism steps.

Subject Keywords

Chemical engineering.

URI

http://etd.lib.metu.edu.tr/upload/3/12611938/index.pdf
https://hdl.handle.net/11511/19692

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Pervaporation of organic/water mixtures by MFI type zeolite membranes synthesized in a flow system Dede, Özlem; Kalıpçılar, Halil; Department of Chemical Engineering (2007) Zeolite membrane synthesis is conventionally carried out in batch systems. Recently, several attempts have been performed to synthesize zeolite membranes in flow systems which can allow preparation of membranes with large specific surface areas. Membranes synthesized in the recirculating flow system had comparable N2/SF6 and n- C4H10/i-C4H10 ideal selectivities with the membranes prepared in the batch system, indicating that good quality membranes can be produced by this method. The objective of this study ...
Synthesis of low silica/alumina zeolite membranes in a flow system Akbay, Sezin; Kalıpçılar, Halil; Department of Chemical Engineering (2007) Zeolite A-type membranes are usually synthesized from hydrogels and rarely synthesized from clear solutions mostly in batch systems. Few studies were carried out using semi-continuous systems for zeolite A membrane synthesis. Zeolite A membranes are mainly used in pervaporation processes for separation of water from water/organic mixtures because of their hydrophilic property. In this study, zeolite A membranes were synthesized on -alumina supports from a clear solution with a molar composition of 49Na2O: ...
Bioprocess development for therapeutical protein production Çelik Akdur, Eda; Çalık, Pınar; Department of Chemical Engineering (2008) In this study, it was aimed to develop a bioprocess using the Pichia pastoris expression system as an alternative to the mammalian system used in industry, for production of the therapeutically important glycoprotein, erythropoietin, and to form stoichiometric and kinetic models. Firstly, the human EPO gene, fused with a polyhistidine-tag and factor-Xa protease target site, in which cleavage produces the native termini of EPO, was integrated to AOX1 locus of P. pastoris. The Mut+ strain having the highest r...
A density functional theory study of ethylene adsorption on Ni-10(111), Ni-13(100) and Ni-10(110) surface cluster models and Ni-13 nanocluster Yilmazer, Nusret Duygu; Fellah, Mehmet Ferdi; Önal, Işık (2010-06-01) Ethylene adsorption was studied by use of DFT/B3LYP with basis set 6-31G(d, p) in Gaussian' 03 software. It was found that ethylene has adsorbed molecularly on all clusters with pi adsorption mode. Relative energy values were calculated to be -50.86 kcal/mol, -20.48 kcal/mol, -32.44 kcal/mol and -39.27 kcal/mol for Ni-13 nanocluster, Ni-10(1 1 1), Ni-13(1 0 0) and Ni10(1 1 0) surface cluster models, respectively. Ethylene adsorption energy is inversely proportional to Ni coordination number when Ni-10(1 1 1...
Chiral seperations by enzyme enhanced ultrafiltration : fractionation ofracemic benzoin Ölçeroğlu, Ayşe Hande; Yılmaz, Levent; Department of Chemical Engineering (2006) In this study, a methodology for separation of chiral molecules, by using enhanced ultrafiltration system was developed. Benzoin was the model chiral molecule studied. In the scope of developing this methodology, some parameters were investigated in the preliminary ultrafiltration experiments in order to set the operation conditions for enhanced ultrafiltration experiments. Due to the slight solubility of benzoin in pure water, 15% (v/v) Polyethylene glycol (PEG 400) and 30 % (v/v) Dimethyl sulfoxide (DMSO)...

Citation Formats

N. D. Yılmazer, “A dft study of ethylene adsorption and hydrogenation mechanisms on nickel,” M.S. - Master of Science, Middle East Technical University, 2010.