Mechanism of formaldehyde steam reforming on Cu (221).

• Main Author: Ng, Benny Jian Wei.
• Other Authors: Lim Kok Hwa
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Chemical engineering::Chemical processes
• Online Access: http://hdl.handle.net/10356/39475
• Institution: Nanyang Technological University

Heavy reliance on fossil fuels has brought about environmental, security and sustainability issues. Fuel cells driven by on-board production of hydrogen via methanol steam reforming (MSR) has been proposed as a viable alternative. Studies had shown that the differences in catalytic performance of various catalysts in MSR were attributed by the difference in reactivity of formaldehyde intermediate on the metal surfaces. Therefore, adsorption study of formaldehyde steam reforming was carried out on (221) surface of Cu using periodic density functional (DF) methods. Investigation was carried out on the terrace, step edge and B5 adsorption sites to determine the most stable adsorption complex. Binding energies of the adsorbates at most stable adsorption sites are shown and analyzed, followed by the derivation of the most favorable reaction pathway. Theoretical results that were calculated show that adsorbates generally prefer to bind to the step Cu atoms on Cu (221). This demonstrates the reactivity of step atoms. In addition, the effects of step when compared to flat surfaces are evident in much stronger adsorption of important reaction species in such H2CO and HCOOH, which have near zero binding energies on flat surfaces. However, the effect of step on the overall reaction pathway is insignificant. On Cu (221), H2CO is thermodynamically favored to react with O atom on the surface, followed by two subsequent H abstractions leading to the formation of CO2. This was found to be similar to that on the flat Cu (100).