Details

Autor(en) / Beteiligte

• Wu, Linke
• Deng, Jiguang
• Liu, Yuxi
• Jing, Lin
• Yu, Xiaohui
• Zhang, Xing
• Gao, Ruyi
• Pei, Wenbo
• Hao, Xiuqing
• Rastegarpanah, Ali
• Hongxing Dai

Titel

Pd/silicalite-1: An highly active catalyst for the oxidative removal of toluene

Ist Teil von

• Journal of environmental sciences (China), 2022-06, Vol.116, p.209-219

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2022

Quelle

MEDLINE

Beschreibungen/Notizen

• •Pd/silicalite-1 (S-1) is prepared via the in situ synthesis method.•Pd nanoparticles are highly dispersed on the surface of S-1.•0.28Pd/S-1-H is obtained after calcination in 10 vol% H2 at 500°C.•0.28Pd/S-1-H shows the best activity and lowest apparent activation energy for toluene combustion.•Oads and Pd° concentrations, toluene adsorption capacity, and acidity govern the catalytic activity. Catalytic combustion is thought as an efficient and economic pathway to remove volatile organic compounds, and its critical issue is the development of high-performance catalytic materials. In this work, we used the in situ synthesis method to prepare the silicalite-1 (S-1)-supported Pd nanoparticles (NPs). It is found that the as-prepared catalysts displayed a hexagonal prism morphology and a surface area of 390−440 m2/g. The sample (0.28Pd/S-1-H) derived after reduction at 500°C in 10 vol% H2 showed the best catalytic activity for toluene combustion (T50% = 180°C and T90% = 189°C at a space velocity of 40,000 mL/(g·hr), turnover frequency (TOFPd) at 160°C = 3.46 × 10−3 sec−1, and specific reaction rate at 160°C = 63.8 µmol/(gPd·sec)), with the apparent activation energy (41 kJ/mol) obtained over the best-performing 0.28Pd/S-1-H sample being much lower than those (51−70 kJ/mol) obtained over the other samples (0.28Pd/S-1-A derived from calcination at 500°C in air, 0.26Pd/S-1-im derived from the impregnation route, and 0.27Pd/ZSM-5-H prepared after reduction at 500°C in 10 vol% H2). Furthermore, the 0.28Pd/S-1-H sample possessed good thermal stability and its partial deactivation due to CO2 or H2O introduction was reversible, but SO2 addition resulted in an irreversible deactivation. The possible pathways of toluene oxidation over 0.28Pd/S-1-H was toluene → p-methylbenzoquinone → maleic anhydride, benzoic acid, benzaldehyde → carbon dioxide and water. We conclude that the good dispersion of Pd NPs, high adsorption oxygen species concentration, large toluene adsorption capacity, strong acidity, and more Pd0 species were responsible for the good catalytic performance of 0.28Pd/S-1-H. Pd nanoparticles are loaded on the surface of silicalite-1 (S-1) and calcined in 10 vol% H2 to obtain the 0.28Pd/S-1-H catalyst using the in situ synthesis method. The good catalytic performance of 0.28Pd/S-1-H is associated with its high adsorbed oxygen species concentration, large toluene adsorption capacity, strong acidity, and high Pd0/Pd2+ molar ratio. [Display omitted]