Understanding Acetaldehyde Thermal Chemistry on the TiO2 (110) Rutile Surface: From Adsorption to Reactivity

详细信息    查看全文

• 作者：Jose虂 Javier Plata ; Veronica Collico ; Antonio M. Ma虂rquez ; Javier Fdez. Sanz
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：February 17, 2011
• 年：2011
• 卷：115
• 期：6
• 页码：2819-2825
• 全文大小：919K
• 年卷期：v.115,no.6(February 17, 2011)
• ISSN：1932-7455

文摘

Plane-wave pseudopotential density functional theory calculations are used to investigate the details of acetaldehyde adsorption and thermal chemistry on the TiO₂ (110) rutile surface. The adsorption properties of a single acetaldehyde molecule on models of stoichimetric, reduced, and oxidized TiO₂ surfaces are first examined. The experimentally observed shift of the temperature-programmed desorption (TPD) maximum on increasing coverage is rationalized on the basis of the adsorbate to surface bonding mechanism. Examination of the thermal chemistry of acetaldehyde on models of the TiO₂ (110) surface allows one to understand the diffusion of acetaldehyde molecules on the surface and the formation of butene, as is experimentally observed. This reaction takes place through a noncatalytic process where the bridge oxygen vacancies play a fundamental role. The molecular details of the process allow one to explain the low amount of butene found in the experiment. The study of the thermal chemistry of acetaldehyde on models of the TiO₂ (110) oxidized surface allows one to understand the stabilization of acetaldehyde in this surface, compared to the reduced surface, through the formation of O-acetaldehyde surface complexes. One of these complexes is found to undergo an easy and not reversible transformation to a highly stable surface acetate, allowing one to rationalize the high temperature required to desorb acetate from this surface and the low quantity of acetate found experimentally.