Enhancement of Photocatalytic Oxidation of Glucose to Value-Added Chemicals on TiO2 Photocatalysts by A Zeolite (Type Y) Support and Metal Loading

Abstract

TiO2-based photocatalysts synthesized by the microwave-assisted sol-gel method was tested in the photocatalytic glucose conversion. Modifications of TiO2 with type-Y zeolite (ZeY) and metals (Ag, Cu, and Ag-Cu) were developed for increasing the dispersion of TiO2 nanoparticles and increasing the photocatalytic activity. Effects of the TiO2 dosage to zeolite ratio (i.e., TiO2/ZeY of 10, 20, 40, and 50 mol %) and the silica to alumina ratio in ZeY (i.e., SiO2:Al2O3 of 10, 100, and 500) were firstly studied. It was found that the specific surface area of TiO2/ZeY was 400–590 m2g−1, which was higher than that of pristine TiO2 (34.38 m2g−1). The good properties of 20%TiO2/ZeY photocatalyst, including smaller particles (13.27 nm) and high surface area, could achieve the highest photocatalytic glucose conversion (75%). Yields of gluconic acid, arabinose, xylitol, and formic acid obtained from 20%TiO2/ZeY were 9%, 26%, 4%, and 35%, respectively. For the effect of the silica to alumina ratio, the highest glucose conversion was obtained from SiO2:Al2O3 ratio of 100. Interestingly, it was found that the SiO2:Al2O3 ratio affected the selectivity of carboxylic products (gluconic acid and formic acid). At a low ratio of silica to alumina (SiO2:Al2O3 = 10), higher selectivity of the carboxylic products (gluconic acid = 29% and formic acid = 32%) was obtained (compared with other higher ratios). TiO2/ZeY was further loaded by metals using the microwave-assisted incipient wetness impregnation technique. The highest glucose conversion of 96.9 % was obtained from 1 wt. % Ag-TiO2 (40%)/ZeY. Furthermore, the bimetallic Ag-Cu-loaded TiO2/ZeY presented the highest xylitol yield of 12.93%.

Synergistic Effects of Co-Doping on Photocatalytic Activity of Titanium Dioxide on Glucose Conversion to Value-Added Chemicals

“…Synergistic effect of co-doping on TiO 2 led to alteration of the photocatalytic mechanism because of modification of the photocatalyst properties. In this study, the glucose conversion yield obtained using the co-doped photocatalyst was comparable with that reported in previous works that modified TiO 2 by surfactant-assisted technique , or changed the photocatalyst form to nanofibers. , The conversion yield obtained was higher than that in a previous report using rutile TiO 2 -based photocatalysts with different selectivity of the derived products in the solvent systems . In addition, the glucose conversion with a short reaction time in this study was relatively high compared with the previous work using heteropolyacid-TiO 2 composites .…”

“…Glucose solution (1 g/L) was prepared in a mixture of distilled water and acetonitrile (10:90 v/v). , Noted that the solvent mixture at 10:90 v/v was selected from a preliminary experiment (Figure S5). The prepared solution (400 mL) was transferred into a Pyrex cylindrical double-walled reactor.…”

Design Aspects of a Continuous Flow Photocatalytic Reactor and its Application to Degrade Methylene Blue and Textile Wastewater

“…The effect of UV light intensity on the decolourization of aqueous solution of MB was investigated by conducting the experiment with MB solution (20 ppm) in the continuous flow rector with 15 W and 50 W UV lamps, respectively and at a catalytic dose of 2 g/L (Figure 6). [45] From the figure, it is observed that, the percent decolorization increased with increase in UV light intensity. This may be because, with increase in UV light intensity, there is increase in portion of catalyst surface irradiated.…”

Editorial Catalysts: Special Issue on Recent Advances in TiO2 Photocatalysts

“…AOPs are highly effective due to the formation of reactive oxygen species, especially hydroxyl radicals, which act as oxidizing agents. Among AOPs, semiconductor photocatalysis, especially with titanium dioxide (TiO 2 ), has a great potential for the decontamination of water and wastewater, exhaust gases, and disinfection [1][2][3][4][5][6][7][8]. This inexpensive, stable, and non-toxic catalyst provides very good removal efficiency.…”

“…However, due to the large energy band gap, its activity in the range of natural solar light is quite limited. For this reason, the development of new TiO 2 -based photocatalysts active in the visible range has become a new research trend [1,3,6,13,[15][16][17][18][19]. The effectivity can also be improved by modifying TiO 2 with noble metals [2,13,15] or by Ti 3+ -self-doped TiO 2 modification [11].…”