Renewable Energy from the Photocatalytic Reduction of CO2 with H2O
Journal
Nanostructure Science and Technology
Journal Volume
Part F10805
Start Page
673
End Page
696
ISSN
15715744
ISBN
9780387484440
Date Issued
2010
Author(s)
Abstract
Sun is the Earth’s ultimate and inexhaustible energy source. With the advantage of generating renewable energy, one of the best routes to remedy CO2 is to transform it to hydrocarbons using photoreduction. CO2 was photocatalytically reduced to produce methanol in an aqueous batch reactor and a steady-state optical–fiber reactor under UV irradiation. Titania and Cu-loaded titania were synthesized using titanium (IV) butoxide by sol-gel method. The catalyst was dip-coated on optical fiber. The optical–fiber photoreactor, comprised of nearly 120 photocatalyst-coated fibers, was designed and assembled to transmit and spread light uniformly inside the reactor. The coating film consisted of very fine spherical particles with diameters of near 14 nm. The XRD spectra indicated the anatase phase for all TiO2 and Cu/TiO2 catalysts. XPS analysis revealed primary Cu2O species on the TiO2 supports. The most active Cu species on TiO2 surface were Cu2O clusters and they played an important role for the formation of methanol. The methanol yield rates increased with UV irradiative intensity. Maximum methanol rate was 0.45 μmol/g cat h using 1.2 wt% Cu/TiO2 catalyst at 129 kPa of CO2, 2.6 kPa of H2O, and 5,000 s mean residence time under 16 W/cm2 UV irradiation. Higher than 2 wt% Cu loading gave a lower rate of methanol yield rate because of the masking effect of Cu2O clusters on the TiO2 surface. A Langmuir–Hinshelwood model was established by correlating experimental data to describe the kinetic behavior. An optimum pressure ratio of H2O/CO2 was found in the photoreduction of CO2 for maximum methanol yield rate.
Subjects
Adsorption Equilibrium Constant
Copper Cluster
Optical Fiber
Pure TiO2
TiO2 Film
Publisher
Springer Publishing Company
Type
book part