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The photochemical activation and reduction of CO 2 over a molecular-sieve-encapsulated rhenium complex was investigated under photoirradiation (l b 350 nm) at room temperature. Re(CO) 3 (bpy)Cl and [Re(CO) 3 (bpy)(py)] were respectively encapsulated in the microporous NaY and the mesoporous AlMCM-41 molecular sieve acting as supramolecular heterogeneous host. The molecular-sieve-encapsulated rhenium complexes were characterized by diffuse reflectance (DR) ultraviolet-visible (UV-vis), photoluminescence, and Fourier transform infrared (FTIR) spectroscopy. The interaction between the excited state of encapsulated rhenium complexes and the adsorbed CO 2 was observed in photoluminescence spectra. The radicals of rhenium complexes encapsulated in NaY and AlMCM-41 were produced with photoirradiation and confirmed by DR UV-vis spectra. By monitoring the photoreaction of CO 2 over the molecular-sieve-encapsulated rhenium complexes using FTIR spectroscopy and gas chromatography, the conversion of CO 2 into CO and carbonate species was observed. The molecularsieve-encapsulated rhenium complexes showed photocatalytic activity for the activation and reduction of CO 2 . Figure 1 Process of photoinduced activation and reduction of CO 2 over encapsulated rhenium complexes: (a) Re(CO) 3 (bpy)-Cl/NaY; (b) [Re(CO) 3 (bpy)(py)] /AlMCM-41.Figure 2 UV-vis absorption spectra of (a) solution of Re(CO) 3 (bpy)Cl in CH 2 Cl 2 , (b) Re(CO) 3 (bpy)Cl/NaY, and (c) Re(CO) 3 (bpy)Cl/NaY after photoirradiation.

Benzene and four polycyclic arenes (PAs) were used as substrates and their hydrogenation reactions were conducted over activated carbon (AC) at 300 °C to examine the relationship between their molecular structures and reactivities. The results show that the AC catalyzed the hydrogenation of the PAs selectively and that the reactivities of the arenes toward hydrogenation were dependent on the hydrogen-accepting abilities of the arenes and on the adsorption strengths of the arenes on the catalyst surface. The related mechanisms for hydrogen transfer were also discussed.

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