Chemistry of thiophene on ZnO, S/ZnO, and Cs/ZnO surfaces: Effects of cesium on desulfurization processes

Journal Article · Thu Jul 01 04:00:00 EDT 1999 · Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical

DOI:https://doi.org/10.1021/jp991051p· OSTI ID:682084

Jirsak, T; Dvorak, J; Rodriguez, J A ^[1]

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1. Brookhaven National Lab., Upton, NY (United States). Dept. of Chemistry

The adsorption of thiophene (C{sub 4}H{sub 4}S) on clean ZnO and oxide surfaces precovered with S and Cs has been studied using synchrotron-based high-resolution photoemission and ab initio self-consistent-field (SCF) calculations On polycrystalline ZnO, C{sub 4}H{sub 4}S is weakly chemisorbed, and most desorbs at temperatures below 250 K. A very small fraction of the adsorbed C{sub 4}H{sub 4}S ({approximately} 0.02 monolayer) that interacts with O-unsaturated Zn sites decomposes on the oxide surface. S adatoms weaken the bonding interactions of thiophene on ZnO, whereas Cs adatoms enhance the adsorption energy of the molecule by at least 5--10 kcal/mol and facilitate the cleavage of C-S bonds. Pure metallic Cs reacts vigorously with C{sub 4}H{sub 4}S, decomposing the molecule at very low temperatures (100--200 K). The Cs atoms supported on ZnO are in an ionic state (Cs{sup {delta}+}), but they retain a large chemical affinity for thiophene. Small amounts of Cs ({approximately}0.2 monolayer) are enough to activate the oxide surface. Results of ab initio SCF calculations indicate that the bonding interactions of thiophene with the (0001)-Zn and (000{bar 1})-O faces of ZnO are weak, and promotion with Cs adatoms considerably improves the energetics for C{sub 4}H{sub 4}S adsorption and C-S bond breaking. The Cs adatoms provide occupied states that are very efficient for bonding interactions with the frontier orbitals of C{sub 4}H{sub 4}S and other S-containing molecules. This should lead to an improvement in the performance of ZnO as a sorbent in desulfurization processes.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 682084
• 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: 26 Vol. 103; ISSN 1089-5647; ISSN JPCBFK
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
ADVANCED PHOTON SOURCE
CESIUM
DESULFURIZATION
PHOTOEMISSION
SELF-CONSISTENT FIELD
SULFUR
THIOPHENE
ZINC OXIDES