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 i...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 m^(2)/g. The sample(0.28Pd/S-1-H)derived after reduction at 500°C in 10 vol% H_(2)showed the best catalytic activity for toluene combustion(T50%= 180℃ and T90%= 189℃ at a space velocity of 40,000 m L/(g·hr), turnover frequency(TOFPd) at 160℃ = 3.46 × 10^(-3)sec^(-1), and specific reaction rate at 160℃ = 63.8μmol/(gPd·sec)), with the apparent activation energy(41 k J/mol) obtained over the bestperforming 0.28Pd/S-1-H sample being much lower than those(51-70 k J/mol) obtained over the other samples(0.28Pd/S-1-A derived from calcination at 500℃ in air, 0.26Pd/S-1-im derived from the impregnation route, and 0.27Pd/ZSM-5-H prepared after reduction at 500℃ in 10 vol% H_(2)). Furthermore, the 0.28Pd/S-1-H sample possessed good thermal stability and its partial deactivation due to CO_(2) or H_(2)O introduction was reversible, but SO_(2) 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 Pd~0 species were responsible for the good catalytic performance of 0.28Pd/S-1-H.展开更多
基金supported by the National Natural Science Committee of China-Liaoning Provincial People’s Government Joint Fund(No.U1908204)the National Natural Science Foundation of China(Nos.21876006 and 21976009)+2 种基金the Foundation on the Creative Research Team Construction Promotion Project of Beijing Municipal Institutions(No.IDHT20190503)the Natural Science Foundation of Beijing Municipal Commission of Education(No.KM201710005004)the Development Program for the Youth Outstanding-Notch Talent of Beijing Municipal Commission of Education(No.CIT&TCD201904019)。
文摘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 m^(2)/g. The sample(0.28Pd/S-1-H)derived after reduction at 500°C in 10 vol% H_(2)showed the best catalytic activity for toluene combustion(T50%= 180℃ and T90%= 189℃ at a space velocity of 40,000 m L/(g·hr), turnover frequency(TOFPd) at 160℃ = 3.46 × 10^(-3)sec^(-1), and specific reaction rate at 160℃ = 63.8μmol/(gPd·sec)), with the apparent activation energy(41 k J/mol) obtained over the bestperforming 0.28Pd/S-1-H sample being much lower than those(51-70 k J/mol) obtained over the other samples(0.28Pd/S-1-A derived from calcination at 500℃ in air, 0.26Pd/S-1-im derived from the impregnation route, and 0.27Pd/ZSM-5-H prepared after reduction at 500℃ in 10 vol% H_(2)). Furthermore, the 0.28Pd/S-1-H sample possessed good thermal stability and its partial deactivation due to CO_(2) or H_(2)O introduction was reversible, but SO_(2) 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 Pd~0 species were responsible for the good catalytic performance of 0.28Pd/S-1-H.
