In this study,commercial V2O5-WO3/TiO2catalysts were deactivated by loading with alkali metals(K and Na).These catalysts were then regenerated by washing with either deionized water or 0.5 mol/L H2SO4(through the ultr...In this study,commercial V2O5-WO3/TiO2catalysts were deactivated by loading with alkali metals(K and Na).These catalysts were then regenerated by washing with either deionized water or 0.5 mol/L H2SO4(through the ultrasonic-assisted method).The samples used in this research were characterized by NH3-temperature programmed desorption(TPD),and X-ray photoelectron spectroscopy(XPS).Results showed that Na2O and K2O doping can poison the V2O5-WO3/TiO2catalyst and that the poisoning effect of Na2O was stronger than that of K2O.However,the Na2O-loaded sample was easier to regenerate than the K2O-loaded sample.The surfaces of catalysts can be sulfated by washing with dilute sulfuric acid because strong acid sites adhere to the catalyst surface.SO42-could also promote catalyst activity.As indicated by the NH3-TPD findings,the deposition of Na2O and K2O could also reduce the amount of desorbed ammonia and destabilize the acid sites,especially strong chemisorption sites.XPS results revealed that catalysts were deactivated by the decrease in the concentration of chemisorbed oxygen[the Oa/(Oα+Oβ)ratio].In the Na2O-doped catalyst,much chemisorbed oxygen was lost(from 28.8%to10.6%).However,the decrease in the Oa/(Oα+Oβ)ratio was less significant in the K2O-doped catalyst(from28.8%to 23.5%).Nonetheless,the binding energies of O1s broadened with respect to both high and low energy.In particular,the binding energy of chemisorbed oxygen increased from 531.5 to 531.8 eV.展开更多
Based on 47 accessions from Ussuri River Valley, Songhua River Valley and Heilong River Valley together with 2 accessions from Russia and 27 accessions of cultivated lotus from other provinces in China, genetic divers...Based on 47 accessions from Ussuri River Valley, Songhua River Valley and Heilong River Valley together with 2 accessions from Russia and 27 accessions of cultivated lotus from other provinces in China, genetic diversity of wild lotus (Nelumbo nucifera) were revealed using RAPD and ISSR markers. Twenty RAPD primers generated 113 loci, of which 71.68% were polymorphic across all sam-ples. The expected heterozygosity was 0.1583. The percentage of polymorphic loci and expected het-erozygosity in the wild lotus were 50.44% and 0.1241, respectively. The parameters of the cultivated lotus were slightly higher, 53.98% and 0.1651 corre-spondingly. Sixteen ISSR primers produced 90 loci. The percentages of polymorphic loci and expected heterozygosity were 41.11% and 0.0851 at species level, 28.89% and 0.0661 for the wild lotus, and 32.22% and 0.0963 for the cultivated lotus. AMOVA analysis of the wild lotus showed that a small number of variances exist among the 3 river valleys (21.68% for RAPD with Gst=0.1312 and 15.11% for ISSR with Gst=0.1352). The molecular variances of both the wild and the cultivated lotuses came predominantly from within the 3 river valleys and the cultivated samples (73.25% for RAPD and 81.11% for ISSR). Variance components from the wild and the cultivated lotus accounted for 19.17% for RAPD and 13.17% for ISSR, and variations among the valleys and the culta seemed the least important (7.585 for RAPD and 5.725 for ISSR). Neighbor-joining analysis demon-strated that considerable differentiation happened between the wild and the cultivated lotus. The wildlotus at middle reaches of the Songhua River Valley seemed to be the centre of remnants, from which it spread to the Ussuri River Valley and the Heilong River Valley. The very limited genetic diversity sug- gests that the wild lotus has experienced severe bot- tleneck effect, founder effect and rebirth effect. Con- sidering its long evolutionary history, scarcity of ge- netic variations and importance in wetland ecosys- tems, we appeal to take lawful展开更多
基金supported by the National Natural Science Foundation of China (21177051)the Fundamental Research Funds for the Central Universities (06101047)Program for New Century Excellent Talents in University (NECT-13-0667)
文摘In this study,commercial V2O5-WO3/TiO2catalysts were deactivated by loading with alkali metals(K and Na).These catalysts were then regenerated by washing with either deionized water or 0.5 mol/L H2SO4(through the ultrasonic-assisted method).The samples used in this research were characterized by NH3-temperature programmed desorption(TPD),and X-ray photoelectron spectroscopy(XPS).Results showed that Na2O and K2O doping can poison the V2O5-WO3/TiO2catalyst and that the poisoning effect of Na2O was stronger than that of K2O.However,the Na2O-loaded sample was easier to regenerate than the K2O-loaded sample.The surfaces of catalysts can be sulfated by washing with dilute sulfuric acid because strong acid sites adhere to the catalyst surface.SO42-could also promote catalyst activity.As indicated by the NH3-TPD findings,the deposition of Na2O and K2O could also reduce the amount of desorbed ammonia and destabilize the acid sites,especially strong chemisorption sites.XPS results revealed that catalysts were deactivated by the decrease in the concentration of chemisorbed oxygen[the Oa/(Oα+Oβ)ratio].In the Na2O-doped catalyst,much chemisorbed oxygen was lost(from 28.8%to10.6%).However,the decrease in the Oa/(Oα+Oβ)ratio was less significant in the K2O-doped catalyst(from28.8%to 23.5%).Nonetheless,the binding energies of O1s broadened with respect to both high and low energy.In particular,the binding energy of chemisorbed oxygen increased from 531.5 to 531.8 eV.
文摘Based on 47 accessions from Ussuri River Valley, Songhua River Valley and Heilong River Valley together with 2 accessions from Russia and 27 accessions of cultivated lotus from other provinces in China, genetic diversity of wild lotus (Nelumbo nucifera) were revealed using RAPD and ISSR markers. Twenty RAPD primers generated 113 loci, of which 71.68% were polymorphic across all sam-ples. The expected heterozygosity was 0.1583. The percentage of polymorphic loci and expected het-erozygosity in the wild lotus were 50.44% and 0.1241, respectively. The parameters of the cultivated lotus were slightly higher, 53.98% and 0.1651 corre-spondingly. Sixteen ISSR primers produced 90 loci. The percentages of polymorphic loci and expected heterozygosity were 41.11% and 0.0851 at species level, 28.89% and 0.0661 for the wild lotus, and 32.22% and 0.0963 for the cultivated lotus. AMOVA analysis of the wild lotus showed that a small number of variances exist among the 3 river valleys (21.68% for RAPD with Gst=0.1312 and 15.11% for ISSR with Gst=0.1352). The molecular variances of both the wild and the cultivated lotuses came predominantly from within the 3 river valleys and the cultivated samples (73.25% for RAPD and 81.11% for ISSR). Variance components from the wild and the cultivated lotus accounted for 19.17% for RAPD and 13.17% for ISSR, and variations among the valleys and the culta seemed the least important (7.585 for RAPD and 5.725 for ISSR). Neighbor-joining analysis demon-strated that considerable differentiation happened between the wild and the cultivated lotus. The wildlotus at middle reaches of the Songhua River Valley seemed to be the centre of remnants, from which it spread to the Ussuri River Valley and the Heilong River Valley. The very limited genetic diversity sug- gests that the wild lotus has experienced severe bot- tleneck effect, founder effect and rebirth effect. Con- sidering its long evolutionary history, scarcity of ge- netic variations and importance in wetland ecosys- tems, we appeal to take lawful
