Reaction pathways of acetylene on Pd/W(211): A TPD and HREELS investigation
Journal Article
·
· Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical
- Rutgers Univ., Piscataway, NJ (United States)
- Exxon Research and Engineering Co., Annandale, NJ (United States). Corporate Research Labs.
In an ongoing investigation to study structure-reactivity relationships on bimetallic surfaces, acetylene cyclotrimerization to form benzene is of particular interest: in this structure-sensitive catalytic reaction, C-C and C-H bonds can be formed readily under ultrahigh vacuum (UHV) conditions without C-C bond breaking. In this paper, the authors present results for acetylene cyclization and hydrogenation on Pd/W(211). Pd on W is chosen because it is a morphologically unstable system, and W(211) facets develop after annealing Pd/W(111) to {ge}700 K. Temperature-programmed desorption (TPD) results exhibit negligible amounts of benzene detected from acetylene adsorption on clean W(211). A single monolayer (ML) of Pd on W(211) decreases the high reactivity toward acetylene decomposition and several different reaction pathways are accessed, including hydrogenation of C{sub 2}H{sub 2} to C{sub 2}H{sub 4} and cyclotrimerization of C{sub 2}H{sub 2} for form C{sub 6}H{sub 6}. The cyclotrimerization reaction produces three benzene desorption states at {approximately}340, {approximately}390, and {approximately}430 K. In addition, the detection of C{sub 4}H{sub 6} during TPD provides evidence that an elusive C{sub 4}H{sub 4} intermediate is present on the surface. Furthermore, ethylene is observed in substantial yields, lending insight into the activity of the bimetallic system. The use of high-resolution electron energy-loss spectroscopy (HREELS) provides complementary information regarding the reaction mechanisms of acetylene on the Pd/W(211) surfaces.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- OSTI ID:
- 315940
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical Journal Issue: 48 Vol. 102; ISSN 1089-5647; ISSN JPCBFK
- Country of Publication:
- United States
- Language:
- English
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