Enhancing the stability of supported noble metal catalysts emerges is a major challenge in both science and industry.Herein,a heterogeneous Pd catalyst(Pd/NCF)was prepared by supporting Pd ultrafine metal nanoparticle...Enhancing the stability of supported noble metal catalysts emerges is a major challenge in both science and industry.Herein,a heterogeneous Pd catalyst(Pd/NCF)was prepared by supporting Pd ultrafine metal nanoparticles(NPs)on nitrogen-doped carbon;synthesized by using F127 as a stabilizer,as well as chitosan as a carbon and nitrogen source.The Pd/NCF catalyst was efficient and recyclable for oxidative carbonylation of phenol to diphenyl carbonate,exhibiting higher stability than Pd/NC prepared without F127 addition.The hydrogen bond between chitosan(CTS)and F127 was enhanced by F127,which anchored the N in the free amino group,increasing the N content of the carbon material and ensuring that the support could provide sufficient N sites for the deposition of Pd NPs.This process helped to improve metal dispersion.The increased metal-support interaction,which limits the leaching and coarsening of Pd NPs,improves the stability of the Pd/NCF catalyst.Furthermore,density functional theory calculations indicated that pyridine N stabilized the Pd^(2+)species,significantly inhibiting the loss of Pd^(2+)in Pd/NCF during the reaction process.This work provides a promising avenue towards enhancing the stability of nitrogen-doped carbon-supported metal catalysts.展开更多
CuCe/Ti-A and CuCe/Ti-R catalysts were prepared using anatase TiO_(2)(TiO_(2)-A)and rutile TiO_(2)(TiO_(2)-R)as supports using the incipient wetness impregnation method for the carbon monoxide(CO)oxidation reaction an...CuCe/Ti-A and CuCe/Ti-R catalysts were prepared using anatase TiO_(2)(TiO_(2)-A)and rutile TiO_(2)(TiO_(2)-R)as supports using the incipient wetness impregnation method for the carbon monoxide(CO)oxidation reaction and were compared with a CuCe-C catalyst prepared using the co-precipitation method.The CuCe/Ti-A catalyst exhibited the highest activity,with complete CO conversion at 90℃,when the gas hourly space velocity was 24000 ml.g^(-1).h^(-1) and the CO concentration was approximately 1%(vol).A series of characterizations of the catalysts revealed that the CuCe/Ti-A catalyst has a larger specific surface area,more Cu+species and oxygen vacancies,and the Cu species of CuCe/Ti-A catalyst is more readily reduced.In situ FT-IR results indicate that the bicarbonate species generated on the CuCe/Ti-A catalyst have lower thermal stability than the carbonate species on CuCe/Ti-R,and will decompose more readily to form CO_(2).Therefore,CuCe/Ti-A has excellent catalytic activity for CO oxidation.展开更多
基金support by the National Natural Science Foundation of China(U21A20306,U20A20152)Natural Science Foundation of Hebei Province(B2022202077).
文摘Enhancing the stability of supported noble metal catalysts emerges is a major challenge in both science and industry.Herein,a heterogeneous Pd catalyst(Pd/NCF)was prepared by supporting Pd ultrafine metal nanoparticles(NPs)on nitrogen-doped carbon;synthesized by using F127 as a stabilizer,as well as chitosan as a carbon and nitrogen source.The Pd/NCF catalyst was efficient and recyclable for oxidative carbonylation of phenol to diphenyl carbonate,exhibiting higher stability than Pd/NC prepared without F127 addition.The hydrogen bond between chitosan(CTS)and F127 was enhanced by F127,which anchored the N in the free amino group,increasing the N content of the carbon material and ensuring that the support could provide sufficient N sites for the deposition of Pd NPs.This process helped to improve metal dispersion.The increased metal-support interaction,which limits the leaching and coarsening of Pd NPs,improves the stability of the Pd/NCF catalyst.Furthermore,density functional theory calculations indicated that pyridine N stabilized the Pd^(2+)species,significantly inhibiting the loss of Pd^(2+)in Pd/NCF during the reaction process.This work provides a promising avenue towards enhancing the stability of nitrogen-doped carbon-supported metal catalysts.
基金supported by the National Natural Science Foundation of China(U21A20306,U20A20152)Natural Science Foundation of Hebei Province(B2022202077).
文摘CuCe/Ti-A and CuCe/Ti-R catalysts were prepared using anatase TiO_(2)(TiO_(2)-A)and rutile TiO_(2)(TiO_(2)-R)as supports using the incipient wetness impregnation method for the carbon monoxide(CO)oxidation reaction and were compared with a CuCe-C catalyst prepared using the co-precipitation method.The CuCe/Ti-A catalyst exhibited the highest activity,with complete CO conversion at 90℃,when the gas hourly space velocity was 24000 ml.g^(-1).h^(-1) and the CO concentration was approximately 1%(vol).A series of characterizations of the catalysts revealed that the CuCe/Ti-A catalyst has a larger specific surface area,more Cu+species and oxygen vacancies,and the Cu species of CuCe/Ti-A catalyst is more readily reduced.In situ FT-IR results indicate that the bicarbonate species generated on the CuCe/Ti-A catalyst have lower thermal stability than the carbonate species on CuCe/Ti-R,and will decompose more readily to form CO_(2).Therefore,CuCe/Ti-A has excellent catalytic activity for CO oxidation.
