Photodegradation catalyst screening by combinatorial methodology

Abstract

In this work, a combinatorial methodology was developed for photodegradation catalyst screening. A fluorescence imaging detection system was designed for high throughput analysis, 1,6-hexamethylenediamine was used as the probe molecule for catalyst testing. The photodegradation activity of catalysts was evaluated by 1,6-hexamethylenediamine consumption during the photodegradation reaction. The methodology could provide reliable results. We found that pure TiO 2, ZrO 2, Nb 2O 5, MoO 3, and WO 3 did not show much activity for 1,6-hexamethylenediamine photodegradation under visible light. TiO 2 catalysts doped with different metal ions were tested. When TiO 2 was doped with Ta 2O 5, Nb 2O 5, V 2O 5, MoO 3, or WO 3, higher activity for photodegradation was observed. The doping of La 3+, Ba 2+, and Br − to TiO 2 did not improve the catalytic activities. When doping TiO 2 with Mn 2+, Cl −, Al 3+, Cu 2+, Fe 3+, Na +, Mg 2+, Li +, F −, Co 2+, or K +, catalytic activity was lower than that of pure TiO 2. After elaborate catalysts screening, we discovered new catalysts, such as 50–70% TiO 2/0–20% WO 3/20–40% VO 2.5 and 20–30% TiO 2/30–50% MoO 3/40–60% VO 2.5 as well as 30% WO 3/20% ZrO 2/50% NbO 2.5 (synthesized from ZrCl 4, NbCl 5, and (NH 4) 5H 5[H 2(WO 4) 6]·H 2O in ethanol solution or suspension) and 60–70% WO 3/Nb 2O 5 (synthesized from WCl 6 and NbCl 5 in ethanol solution). We observed that the catalytic activity is sensitive to preparation methods and catalyst specific surface areas. When P123 (HO(CH 2CH 2O) 20(CH 2CH(CH 3)O) 70(CH 2CH 2O) 20H, designated EO 20PO 70EO 20) was used as template to synthesize mesoporous materials, the mesoporous catalysts showed higher activity than regular catalytic materials.