One‐step production of pyruvic acid through selective oxidation of glycerol was investigated using lead promoted platinum/activated carbon(Pb‐Pt/AC)catalysts under mild conditions.The results of N2physisorption,X‐r...One‐step production of pyruvic acid through selective oxidation of glycerol was investigated using lead promoted platinum/activated carbon(Pb‐Pt/AC)catalysts under mild conditions.The results of N2physisorption,X‐ray diffraction,X‐ray photoelectron spectroscopy,and high‐resolution transmission electron microscopy revealed that the alloy phases of PtPb and PtxPb were favorable for pyruvic acid production from glycerol oxidation,whereas the Pb3(CO3)2(OH)2and surface Pb0species inhibited the glycerol conversion.The loading of Pb and the catalyst preparation method(including impregnation and deposition precipitation)affected the formation of different metal species.Pyruvic acid was obtained at a yield of18.4%on a5.0wt%Pb‐5.0wt%Pt/AC catalyst prepared by co‐deposition precipitation method and500°C argon treatment.展开更多
Phosphorus （P） and metal （M） components were incorporated into promoters for enhancing FCC propylene yield, and the reactive behavior of promoters, before and after modification, were investigated. The results sho...Phosphorus （P） and metal （M） components were incorporated into promoters for enhancing FCC propylene yield, and the reactive behavior of promoters, before and after modification, were investigated. The results showed that both LPG and propylene yields were increased, and propylene selectivity was improved after the incorporation of P or M into the matrix, resulting in an increased C3 to C4 ratio in LPG during FCC process. But the sole incorporation of M into the matrix also led to an increase in coke and H2 yields on the other hand. Simultaneous modification of the matrix by P and M components resulted in more enhancement in propylene yield and selectivity along with little influence on FCC product distribution. Physico-chemical characterizations and model compound reactions were used to assist in analyzing the mechanism for improving propylene selectivity. Two types of active centers could strengthen the oligomerization of C4 olefins in LPG and these oligomers could be further cracked into C3 olefins on ZSM-5 zeolite, therefore maximizing the ratio of C3 to C4 in liquefied petroleum gas obtained during FCC process.展开更多
To determine the chemical constituents of volatile components in saffron from the Tibet Autonomous Region and the Henan Province of China and to compare the chemical composition difference in the saffron,the total vol...To determine the chemical constituents of volatile components in saffron from the Tibet Autonomous Region and the Henan Province of China and to compare the chemical composition difference in the saffron,the total volatile components were extracted by ultrasonic-assisted solvent extraction（USE）,using five different solvents：diethyl ether,ethanol,ethyl acetate, dichloromethane and acetone,analyzed using gas chromatography-mass spectrometry（GC-MS）and compared to the standard MS data,and their relative contents were calculated by area normalization.The results showed both that USE was an efficient and rapid method for the extraction of the volatile components from saffron and that the components extracted from the same sample using different solvents were different.Comparison of the experimental results of saffron from the Tibet Autonomous Region and the Henan Province of China showed that their volatile components were different in their chemical composition and in their relative percentages.USE/GC-MS is a simple,rapid,and effective method for the analysis of volatile oil components in saffron.展开更多
基金supported by the National Natural Science Foundation of China(21176236)~~
文摘One‐step production of pyruvic acid through selective oxidation of glycerol was investigated using lead promoted platinum/activated carbon(Pb‐Pt/AC)catalysts under mild conditions.The results of N2physisorption,X‐ray diffraction,X‐ray photoelectron spectroscopy,and high‐resolution transmission electron microscopy revealed that the alloy phases of PtPb and PtxPb were favorable for pyruvic acid production from glycerol oxidation,whereas the Pb3(CO3)2(OH)2and surface Pb0species inhibited the glycerol conversion.The loading of Pb and the catalyst preparation method(including impregnation and deposition precipitation)affected the formation of different metal species.Pyruvic acid was obtained at a yield of18.4%on a5.0wt%Pb‐5.0wt%Pt/AC catalyst prepared by co‐deposition precipitation method and500°C argon treatment.
文摘Phosphorus （P） and metal （M） components were incorporated into promoters for enhancing FCC propylene yield, and the reactive behavior of promoters, before and after modification, were investigated. The results showed that both LPG and propylene yields were increased, and propylene selectivity was improved after the incorporation of P or M into the matrix, resulting in an increased C3 to C4 ratio in LPG during FCC process. But the sole incorporation of M into the matrix also led to an increase in coke and H2 yields on the other hand. Simultaneous modification of the matrix by P and M components resulted in more enhancement in propylene yield and selectivity along with little influence on FCC product distribution. Physico-chemical characterizations and model compound reactions were used to assist in analyzing the mechanism for improving propylene selectivity. Two types of active centers could strengthen the oligomerization of C4 olefins in LPG and these oligomers could be further cracked into C3 olefins on ZSM-5 zeolite, therefore maximizing the ratio of C3 to C4 in liquefied petroleum gas obtained during FCC process.
文摘To determine the chemical constituents of volatile components in saffron from the Tibet Autonomous Region and the Henan Province of China and to compare the chemical composition difference in the saffron,the total volatile components were extracted by ultrasonic-assisted solvent extraction（USE）,using five different solvents：diethyl ether,ethanol,ethyl acetate, dichloromethane and acetone,analyzed using gas chromatography-mass spectrometry（GC-MS）and compared to the standard MS data,and their relative contents were calculated by area normalization.The results showed both that USE was an efficient and rapid method for the extraction of the volatile components from saffron and that the components extracted from the same sample using different solvents were different.Comparison of the experimental results of saffron from the Tibet Autonomous Region and the Henan Province of China showed that their volatile components were different in their chemical composition and in their relative percentages.USE/GC-MS is a simple,rapid,and effective method for the analysis of volatile oil components in saffron.
