PdPtIy/I/V[sub.2]O[sub.5]-TiO[sub.2]: Highly Active Catalysts with Good Moisture- and Sulfur Dioxide-Resistant Performance in Toluene Oxidation

• Published in: Catalysts 2022-10, Vol.12 (11)
• Main Authors: Sun, Jingjing, Liu, Yuxi, Deng, Jiguang, Jing, Lin, Bao, Minming, Sun, Qinpei, Li, Linlin, Wu, Linke, Hao, Xiuqing, Dai, Hongxing
• Format: Article
• Language: English
• Subjects: Air pollution; Air quality management; Catalysts; Energy conservation; Germany; Oxidation-reduction reaction; Sulfur dioxide; Toluene
• ISSN: 2073-4344; 2073-4344
• DOI: 10.3390/catal12111302

Catalytic performance and moisture and sulfur dioxide resistance are important for a catalyst used for the oxidation of volatile organic compounds (VOCs). Supported noble metals are active for VOC oxidation, but they are easily deactivated by water and sulfur dioxide. Hence, it is highly desired to develop a catalyst with high performance and good moisture and sulfur dioxide resistance in the oxidation of VOCs. In this work, we first adopted the hydrothermal method to synthesize a V[sub.2]O[sub.5]-TiO[sub.2] composite support, and then employed the polyvinyl alcohol (PVA)-protecting NaBH[sub.4] reduction strategy to fabricate xPdPty/V[sub.2]O[sub.5]-TiO[sub.2] catalysts (x and y are the PdPty loading (0.41, 0.46, and 0.49 wt%) and Pt/Pd molar ratio (2.10, 0.85, and 0.44), respectively; the corresponding catalysts are denoted as 0.46PdPt[sub.2.10]/V[sub.2]O[sub.5]-TiO[sub.2], 0.41PdPt[sub.0.85]/V[sub.2]O[sub.5]-TiO[sub.2], and 0.49PdPt[sub.0.44]/V[sub.2]O[sub.5]-TiO[sub.2]). Among all the samples, 0.46PdPt[sub.2.10]/V[sub.2]O[sub.5]-TiO[sub.2] exhibited the best catalytic activity for toluene oxidation (T[sub.50%] = 220 °C and T[sub.90%] = 245 °C at a space velocity of 40,000 mL/(g h), apparent activation energy (E[sub.a]) = 45 kJ/mol), specific reaction rate at 230 °C = 98.6 μmol/(g[sub.Pt] s), and turnover frequency (TOF[sub.Noble] [sub.metal]) at 230 °C = 142.2 × 10[sup.−] [sup.3] s[sup.−] [sup.1]. The good catalytic performance of 0.46PdPt[sub.2.10]/V[sub.2]O[sub.5]-TiO[sub.2] was associated with its well-dispersed PdPt[sub.2.10] nanoparticles, high adsorbed oxygen species concentration, good redox ability, large toluene adsorption capacity, and strong interaction between PdPty and V[sub.2]O[sub.5]-TiO[sub.2]. No significant changes in toluene conversion were detected when 5.0 vol% H[sub.2]O or 50 ppm SO[sub.2] was introduced to the reaction system. According to the characterization results, we can realize that vanadium is the main site for SO[sub.2] adsorption while PdO is the secondary site for SO[sub.2] adsorption, which protects the active Pt site from being poisoned by SO[sub.2], thus making the 0.46PdPt[sub.2.10]/V[sub.2]O[sub.5]TiO[sub.2] catalyst show good sulfur dioxide resistance.