TiO2–Al2O3 binary mixed oxide surfaces for photocatalytic NOx abatement

Abstract

a b s t r a c tTiO 2 -Al 2 O 3 binary oxide surfaces were utilized in order to develop an alternative photocatalytic NO x abatement approach, where TiO 2 sites were used for ambient photocatalytic oxidation of NO with O 2 and alumina sites were exploited for NO x storage. Chemical, crystallographic and electronic structure of the TiO 2 -Al 2 O 3 binary oxide surfaces were characterized (via BET surface area measurements, XRD, Raman spectroscopy and DR-UV-Vis Spectroscopy) as a function of the TiO 2 loading in the mixture as well as the calcination temperature used in the synthesis protocol. 0.5 Ti/Al-900 photocatalyst showed remarkable photocatalytic NO x oxidation and storage performance, which was found to be much superior to that of a Degussa P25 industrial benchmark photocatalyst (i.e. 160% higher NO x storage and 55% lower NO 2 (g) release to the atmosphere). Our results indicate that the onset of the photocatalytic NO x abatement activity is concomitant to the switch between amorphous to a crystalline phase with an electronic band gap within 3.05-3.10 eV; where the most active photocatalyst revealed predominantly rutile phase together and anatase as the minority phase.

Noble-Metal-Free NOx Storage over Ba-Modified TiO2 Photocatalysts under UV-Light Irradiation at Low Temperatures

“…This result clearly indicates that the Ba modification suppressed the growth of TiO 2 particles. Similar effects were previously reported for metal doping into TiO 2 (e.g., Si, Zr, [35] La, [36] and Al [37] ). The Ba loading enhanced the thermal stability of the catalyst, which should be one of the reasons for the higher NSC of the Ba/TiO 2 catalyst than that of the TiO 2 catalyst.…”

Influence of the sol–gel preparation method on the photocatalytic NO oxidation performance of TiO2/Al2O3 binary oxides

“…TiO 2 /Al 2 O 3 binary oxide materials were prepared by two different sol-gel synthesis protocols denoted as P1 and P2 which were described in detail in our earlier reports [11,12,33,35]. Briefly, in the first synthetic protocol (P1), ␥-Al 2 O 3 (PURALOXS Ba200, 200 m 2 /g, SASOL GmbH, Germany) and TiCl 4 (Fluka, titanium (IV) chloride solution) were used as starting materials.…”

“…Synthesized P1 and P2 materials were subsequently calcined in air for 2 h at temperatures ranging between 150 and 1000 • C. In the synthesized materials, TiO 2 to Al 2 O 3 mole ratios were adjusted to be either 0.5 or 1.0. These ratios were chosen based on our previous studies, which indicated that for (P2) Ti/Al materials, TiO 2 to Al 2 O 3 mole ratios of 0.5 and 1.0 yielded some of the best performing photocatalysts [33]. Currently synthesized samples are labeled as "(P#) n Ti/Al-T", where P# denotes the utilized synthesis protocol (i.e.…”

“…A custom-design photocatalytic flow reactor system was used in the photocatalytic activity measurements [33,37]. The flow reactor system consisted of a gas manifold system, mass flow controllers (MKS 1479A), a capacitance pressure gauge (MKS Baratron 622B), a custom-made photocatalytic reactor and a chemiluminescence NO x analyzer (Horiba APNA 370).…”

“…In a recent study, we have reported a TiO 2 /Al 2 O 3 binary oxide system demonstrating a promising gas-phase photocatalytic DeNO x performance, which was found to be superior to a commercial TiO 2 (Degussa P25) benchmark photocatalyst [33,34]. This material was designed to demonstrate a novel approach which is essentially a fusion of NSR and PCO technologies.…”