Photocatalytic Process for CO₂ Emission Reduction from Industrial Flue Gas Streams

Abstract

At present, carbon dioxide (CO 2 ) is the largest contributor among greenhouse gases. This article addresses the potential application of photocatalysis to the reduction of CO 2 emissions from industrial flue gas streams. Not only does this process remove CO 2 , but it can also convert CO 2 into other chemical commodities such as methane, methanol, and ethanol. In addition, the photocatalytic process can consume less energy than conventional methods by harnessing solar energy. Given these advantages, photocatalysis is an attractive alternative for CO 2 capture. This article reviews the principle of photocatalysis; existing literature related to photocatalytic CO 2 reduction; and the effects of important parameters on process performance, including light wavelength and intensity, type of reductant, metal-modified surface, temperature, and pressure. Finally, we discuss various system configurations for UV and solar photocatalytic reactors. The advances in photocatalysis technology indicate a promising application potential for significant reductions of CO 2 emissions and a positive impact on climate change effects.

Comparison of CO2 Photoreduction Systems: A Review

“…The possible reactions that can occur in the reduction of CO 2 in aqueous medium are shown in Scheme 1 (Inoue et al, 1979;Sutin et al, 1997;Fujita 1999;Usubharatana et al, 2006;Indrakanti et al, 2009). It is apparent from Scheme 1 that CO 2 photoreduction involves multiple steps.…”

“…In the case of doping or coating metals, this can be explained by considering the metal dopants/islands as sinks for the excited TiO 2 electrons (Usubharatana et al, 2006). When the excited electron is injected into the conduction band of the TiO 2 and starts to travel across the TiO 2 crystal lattice, it becomes trapped by the metal dopants because of the relative lower energy state that it can obtain if it goes to the metal dopant.…”

“…There are several reviews on CO 2 photoreduction (Sutin et al, 1997;Song, 2006;Usubharatana et al, 2006;Kitano et al, 2007;Indrakanti et al, 2009;Morris et al, 2009;Dorner et al, 2010;Roy et al, 2010;Biswas et al, 2011;Windle and Perutz, 2012;Hong et al, 2013), covering both fundamental CO 2 photoreduction mechanisms and practical photocatalyst development. This article intends to provide a state-of-the-art overview of the basics of CO 2 photoreduction pathways, and a comparison of different CO 2 photoreduction systems as listed below: (1) Biological systems, including mainly algae; (2) Inorganic photocatalysts, mostly transition metal oxides (or semiconductors), in particular TiO 2 -based catalysts; (3) Organic photocatalysts, including mainly metalorganic complexes; and (4) inorganic and organic/biological hybrid, or the so-called biomimetic systems, consisting of enzyme-activated or dye-sensitized semiconductors.…”

Photoinduced electron transfer and photodegradation of malonic acid at Au/TiO2 investigated by in situ ATR-IR spectroscopy

“…Photocatalytic reactions over TiO 2 play an essential role in many applications, such as the degradation of organic pollutants, water splitting, CO 2 reduction and solar cells [1,2]. A photocatalytic reaction is initiated by electron-hole pair generation upon band gap excitation.…”

Nanostructured Graphene-Titanium Dioxide Composites Synthesized by a Single-Step Aerosol Process for Photoreduction of Carbon Dioxide

“…A widely accepted method that is used to slow down the e --h + recombination rate is to deposit metal nanoparticles (NPs), such as platinum, copper, or iron, on semiconductor surfaces (Tseng et al, 2004;Usubharatana et al, 2006;Indrakanti et al, 2009;Wang et al, 2012a). These metal NPs serve as electron sinks and, thus, separate the e --h + pair to enhance the photoreduction efficiency.…”