Photosensitized reduction of CO/sub 2/ to CH/sub 4/ and H/sub 2/ evolution in the presence of ruthenium and osmium colloids: strategies to design selectivity of products distribution

Journal Article · Wed Sep 30 04:00:00 EDT 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00254a029· OSTI ID:6064781

Willner, I; Maidan, R; Mandler, D; Duerr, H; Doerr, G; Zengerle, K

Photoreduction of CO/sub 2/ to methane and higher hydrocarbons is accomplished in aqueous solutions by using visible light and Ru or Os colloids as catalysts. One system is composed of Ru(II) tris(bipyridine), Ru(bpy)/sub 3//sup 2 +/, as photosensitizer, triethanolamine, TEOA, as electron donor, and one of the following bipyridinium charge relays: N,N'-dimethyl-2,2'-bipyridinium, MQ/sup 2 +/ (1), N,N'-trimethylene-2,2'-bipyridinium, TQ/sup 2 +/ (2), N,N'-tetramethylene-2,2'-bipyridinium, DQ/sup 2 +/ (3), or N,N'-bis-(3-sulfonatopropyl)-3,3'-dimethyl-4,4'-bipyridinium, MPVS/sup 0/ (4). Illumination of these systems under CO/sub 2/ in the presence of Ru or Os colloids results in the formation of methane and ethylene and in H/sub 2/ evolution. In the second system, illumination of an aqueous solution under CO/sub 2/ that includes Ru(II) tris(bipyrazine) as sensitizer, TEOA as electron donor, and the Ru colloids leads to the formation of methane, ethylene, and ethane, and no H/sub 2/-evolution occurs. The reduction process of CO/sub 2/ proceeds via electron transfer of metal-activated CO/sub 2/ rather than through a hydrogenation route. Detailed studies show that the H/sub 2/-evolution process can be inhibited by the addition of bipyrazine, while CO/sub 2/ reduction is inhibited in the presence of added thiols. Methanation of CO/sub 2/ by hydrogen proceeds in the dark in the presence of Pt and Ru or Os colloids and in the presence of MQ/sup 2 +/ (1). The need for the electron relay implies that the methanation process occurs through an electron-transfer mechanism.

• Research Organization: Hebrew Univ. of Jerusalem, Israel
• OSTI ID: 6064781
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:20; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
080106 -- Hydrogen-- Production-- Biosynthesis & Photochemical Processes
090121* -- Hydrocarbon Fuels-- Chemical Synthesis-- (1976-1989)
10 SYNTHETIC FUELS
ALKANES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHEMISTRY
COLLOIDS
DATA
DISPERSIONS
ELEMENTS
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGEN PRODUCTION
INFORMATION
METALS
METHANATION
METHANE
NUMERICAL DATA
ORGANIC COMPOUNDS
OSMIUM
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOSENSITIVITY
PLATINUM METALS
REDUCTION
RUTHENIUM
SENSITIVITY
SYNTHESIS
TRANSITION ELEMENTS