The cleavage of the aliphatic chain or ether bond connecting the polycyclic aromatic hydrocarbons in coal can be achieved by not only hydrogenation reduction but also oxidative acid treatment. In this paper, coal samp...The cleavage of the aliphatic chain or ether bond connecting the polycyclic aromatic hydrocarbons in coal can be achieved by not only hydrogenation reduction but also oxidative acid treatment. In this paper, coal samples from Wucaiwan in Xinjiang were pretreated with HNO3 followed by mixed acids/ultrasound treatment. The depolymerized coal samples obtained under different pH conditions were then separated by fractional washing. The structures and properties of the resulting coal samples were studied by elemental analysis, FT-IR, XRD, TG-DTA, TEM, UV-Vis, and PL. The results showed that when pH = 0.012, the obtained coal samples were fragments stripped off from the raw coal samples by ultrasound in strong acid conditions, aliphatic hydrocarbons linked with oxygen-containing groups such as nitro group, a small amount of small aromatic molecules and mineral salts; when pH -- 1.99-4.09, the obtained coal samples were polycyclic aromatic hydrocarbons linked with oxygen-containing groups such as nitro group,possessing the annulus wall of multilayer graphene fragment structures built up by sp2 carbons, and they are typical fluorescent substances of carbon nanoparticle structure. The former has no solubility in organic solvents, while the latter can be well dissolved in polar solvents such as acetone. All the depolymerized coal samples obtained under different pH conditions exhibited good absorption and ability of fluorescence emission.展开更多
Thermal decomposition processes taking place in solid state complex of Zn1-xMnxC2O4·2H2O have been investigated in air using TG-DTG/DTA, XRD and TEM techniques. TG-DTG/DTA curves showed that the decomposition pro...Thermal decomposition processes taking place in solid state complex of Zn1-xMnxC2O4·2H2O have been investigated in air using TG-DTG/DTA, XRD and TEM techniques. TG-DTG/DTA curves showed that the decomposition proceeded through two well-defined steps with DTA peaks closely to correspond to the weight loss. XRD and TEM showed that the final decomposition product of Zn1-xMnxC2O4·2H2O was Zn1-xMnxO and most of the individual particles were of size 10-13 nm. Kinetics analysis of Zn1-xMnxC2O4·2H2O decomposition steps was performed under nonisothermai conditions, the activation energies were estimated by Friedman and Flynn-Wall-Ozawa （FWO） methods, and the most probable kinetic model has been estimated with multiple linear regression method. The activation energies for the two decomposition steps of Zn1-xMnxC2O4·2H2O were 155.7513 and 215.9397 kJ/mol, respectively.展开更多
文摘The cleavage of the aliphatic chain or ether bond connecting the polycyclic aromatic hydrocarbons in coal can be achieved by not only hydrogenation reduction but also oxidative acid treatment. In this paper, coal samples from Wucaiwan in Xinjiang were pretreated with HNO3 followed by mixed acids/ultrasound treatment. The depolymerized coal samples obtained under different pH conditions were then separated by fractional washing. The structures and properties of the resulting coal samples were studied by elemental analysis, FT-IR, XRD, TG-DTA, TEM, UV-Vis, and PL. The results showed that when pH = 0.012, the obtained coal samples were fragments stripped off from the raw coal samples by ultrasound in strong acid conditions, aliphatic hydrocarbons linked with oxygen-containing groups such as nitro group, a small amount of small aromatic molecules and mineral salts; when pH -- 1.99-4.09, the obtained coal samples were polycyclic aromatic hydrocarbons linked with oxygen-containing groups such as nitro group,possessing the annulus wall of multilayer graphene fragment structures built up by sp2 carbons, and they are typical fluorescent substances of carbon nanoparticle structure. The former has no solubility in organic solvents, while the latter can be well dissolved in polar solvents such as acetone. All the depolymerized coal samples obtained under different pH conditions exhibited good absorption and ability of fluorescence emission.
基金Project supported by the National Natural Science Foundation of China （No. 20071026）.
文摘Thermal decomposition processes taking place in solid state complex of Zn1-xMnxC2O4·2H2O have been investigated in air using TG-DTG/DTA, XRD and TEM techniques. TG-DTG/DTA curves showed that the decomposition proceeded through two well-defined steps with DTA peaks closely to correspond to the weight loss. XRD and TEM showed that the final decomposition product of Zn1-xMnxC2O4·2H2O was Zn1-xMnxO and most of the individual particles were of size 10-13 nm. Kinetics analysis of Zn1-xMnxC2O4·2H2O decomposition steps was performed under nonisothermai conditions, the activation energies were estimated by Friedman and Flynn-Wall-Ozawa （FWO） methods, and the most probable kinetic model has been estimated with multiple linear regression method. The activation energies for the two decomposition steps of Zn1-xMnxC2O4·2H2O were 155.7513 and 215.9397 kJ/mol, respectively.
