Impact of Pd Loading on CO2 Reduction Performance over Pd/TiO2 with H2 and H2O

Abstract

This study investigated the impact of molar ratio of CO 2 to reductants H 2 O and H 2 , as well as Pd loading weight on CO 2 reduction performance with Pd/TiO 2 as the photocatalyst. The Pd/TiO 2 film photocatalyst is prepared by the sol-gel and dipcoating process to prepare TiO 2 film and the pulse arc plasma method is used to dope Pd on TiO 2 film. The prepared Pd/TiO 2 film was characterized by SEM, EPMA, STEM, EDS, and EELS. This study also investigated the performance of CO 2 reduction under the illumination condition of Xe lamp with or without ultraviolet (UV) light. As a result, it is revealed that when the molar ratio of CO 2 /H 2 /H 2 O is set at 1:0.5:0.5, the best CO 2 reduction performance has been obtained under the illumination condition of Xe lamp with and without UV light. In addition, it is found that the optimum Pd loading weight is 3.90 wt%. The maximum molar quantities of CO and CH 4 produced per unit weight of photocatalyst are 30.3 μmol/g and 22.1 μmol/g, respectively, for the molar ratio of CO 2 /H 2 /H 2 O = 1:0.5:0.5 under the condition of Xe lamp illumination with UV light. With UV light, C 2 H 4 and C 2 H 6 , as well as CO and CH 4 are also produced by the Pd/TiO 2 film photocatalyst prepared in this study.

Utilization from ultraviolet to infrared light for CO2 reduction with P4O10/TiO2 photocatalyst

“…We prepared the TiO 2 film by sol-gel and dip-coating process. [29][30][31] [(CH 3 ) 2 CHO] 4 Ti (purity: 95 wt%, producer: Nacalai Tesque Co., Kyoto, Japan) of 0.3 mol, anhydrous C 2 H 5 OH (purity: 99.5 wt%, producer: Nacalai Tesque Co., Kyoto, Japan) of 2.4 mol, distilled water of 0.3 mol, and HCl (purity: 35 wt%, producer: Nacalai Tesque Co., Kyoto, Japan) of 0.07 mol were mixed to prepare the TiO 2 sol solution. We coat the TiO 2 film on a netlike glass fiber (SILLIGLASS U, producer: Nihonmuki Co., Tokyo, Japan) via sol-gel and dipcoating process.…”

“…The characteristics of external and crystal structure of P loaded TiO 2 film were evaluated by SEM (JXA-8530F, producer: JEOL Lt., Tokyo, Japan) and EPMA (JXA-8530F, producer: JEOL Ltd., Tokyo, Japan). [29][30][31] In these procedures, we use electron to characterize a sample. Therefore, the sample should conduct electricity.…”

“…), TiO 2 film or P 4 O 10 /TiO 2 which is coated on netlike glass disc with a scale of 50 mm (D.)×1 mm (t.) positioned on the Teflon cylinder with a scale of 50 mm (H.)×50 mm (D.), a quartz glass disc having a scale of 84 mm (D.)×10 mm (t.), a sharp cur filter removing the wavelength of light which is below 400 nm (SCF-49.5C-42L, producer: SIGMA KOKI CO LTD., Tokyo, Japan) or 800 nm (ITF-50C-85IR, producer: SIGMA KOKI CO. LTD., Tokyo, Japan), a 150 W Xe lamp (L2175, producer: Hamamatsu Photonics K. K.), mass flow controller and CO 2 gas cylinder (purity: 99.995 vol%) in case of CO 2 reduction experiment with H 2 O. 29 The reactor size for charging CO 2 is 1.25×10 -4 m 3 . The light of Xe lamp located on the stainless tube is illuminated toward TiO 2 film or P 4 O 10 /TiO 2 film passing the sharp cut filter and the quartz glass disc positioned on the top of stainless tube.…”

“…Though the previous studies investigated CO 2 reduction reacting with H 2 O or H 2 , 22,23 the effect of NH 3 including 3H + , which outmatches H 2 O and H 2 , on photocatalytic CO 2 reduction performance is not investigated yet except for the previous studies carried out by the authors using Fe, 28 Cu 29,30 or Pd. 31 They have been investigated the combination of CO 2 , H 2 O and NH 3 .…”

“…31 They have been investigated the combination of CO 2 , H 2 O and NH 3 . [28][29][30][31] However, regarding the reaction scheme to reduce CO 2 with NH 3 , we can show it as follows: 27,32 <Photocatalytic reaction process>…”