Ferrous ions as catalysts for photochemical reduction of CO{sub 2} in homogeneous solutions
Ferrous ions are found to catalyze the photochemical reduction of CO{sub 2} to CO in acetonitrile (ACN) solutions containing triethylamine (TEA) or triethanolamine (TEOA) as reductive quenchers and p-terphenyl (TP) as a photosensitizer. TP is photoreduced to form the radical anion, TP{sup {sm_bullet}{minus}}, which reduces Fe(II) ions. The rate constant for the reduction of Fe(II) by TP{sup {sm_bullet}{minus}} was determined by pulse radiolysis in ACN/TEOA solutions and found to be (1.2 {+-} 0.4) x 10{sup 8} L mol{sup {minus}1}s{sup {minus}1}. The Fe(I) ions produced are expected to react with Co{sub 2} to form an adduct that is equivalent to the adduct known to be formed upon reaction of CO{sub 2}{sup {sm_bullet}{minus}} with Fe(II) complexes. Subsequent reduction of the Fe-CO{sub 2} adduct leads to formation of CO. Fe(I) can also undergo protonation and form H{sub 2}. After extensive irradiation, photochemical production of CO stops, probably due to competition between CO and CO{sub 2} for the Fe(I) binding sites. Addition of CO to the solution enhances the photochemical production of H{sub 2}.
- Research Organization:
- National Inst. of Standards and Technology, Gaithersburg, MD (US)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 20075897
- Journal Information:
- Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Vol. 104, Issue 19; Other Information: PBD: 18 May 2000; ISSN 1089-5639
- Country of Publication:
- United States
- Language:
- English
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