Six kinds of galena with different impurities were synthesized and the effects of impurities on the floatability of galena were investigated. The thermodynamic and kinetic parameters on the galena surface were measure...Six kinds of galena with different impurities were synthesized and the effects of impurities on the floatability of galena were investigated. The thermodynamic and kinetic parameters on the galena surface were measured using microcalorimetry, and the adsorption configuration and energy of butyl xanthate on the surfaces of galena with different impurities were simulated by density functional theory. Flotation experiments showed that Ag and Bi significantly promoted the recovery of galena, while Zn, Sb, Mn, and Cu reduced the recovery of the flotation. Microthermokinetic results indicated that the absolute value of xanthate adsorption heat was directly proportional to the flotation recovery of galena. Adsorption heat and reaction rate coefficients of xanthate on galena containing Ag or Bi were larger than those on pure galena, but smaller on galena containing Cu or Sb. Additionally, the relationship between the heat of unsaturated adsorption of xanthate and the adsorption energy of impurity atom on galena surface was investigated.展开更多
A series of CeO2‐MnOx‐Al2O3 mixed oxide catalysts （Ce：Mn：Al mole ratio=6：4：x, x=0.25, 0.5, 1, 2） were prepared by a simple one‐step inverse co‐precipitation method to investigate the influence of the incorpo...A series of CeO2‐MnOx‐Al2O3 mixed oxide catalysts （Ce：Mn：Al mole ratio=6：4：x, x=0.25, 0.5, 1, 2） were prepared by a simple one‐step inverse co‐precipitation method to investigate the influence of the incorporation of Al3＋ into CeO2‐MnOx mixed oxides. CeO2‐MnOx, CeO2‐Al2O3, and MnOx‐Al2O3 mixed oxides, and CeO2 were prepared by the same method for comparison. The samples were characterized by XRD, Raman, N2 physisorption, H2‐TPR, XPS, and in situ DRIFTS. The catalytic re‐duction of NO by CO was chosen as a model reaction to evaluate the catalytic performance. The incorporation of a small amount of Al3＋into CeO2‐MnOx mixed oxides resulted in a decrease of crys‐tallite size, with the increase of the BET specific surface area and pore volume, as well as the in‐crease of Ce3＋and Mn4＋. The former benefits good contact between catalyst and reactants, and the latter promotes the adsorption of CO and the desorption, conversion and dissociation of adsorbed NO. All these enhanced the catalytic performance for the NO＋CO model reaction. A reaction mecha‐nism was proposed to explain the excellent catalytic performance of CeO2‐MnOx‐Al2O3 catalysts for NO reduction by CO.展开更多
Halo-olefinic impurities in 1,1,1,3,3-pentafluoropropane （HFC-245fa） product used as blowing agents, etc. could damage the human body and must be removed. Activated carbon was treated by HCI, HN03 and NaOH, respecti...Halo-olefinic impurities in 1,1,1,3,3-pentafluoropropane （HFC-245fa） product used as blowing agents, etc. could damage the human body and must be removed. Activated carbon was treated by HCI, HN03 and NaOH, respectively. The adsorptive performance of unmodified and modified activated carbons for the removal of a low con- tent of l-chloro-3,3,3-trifluoro-l-propene （HCFC-1233zd）, 1,3,3,3-tetrafluoro-l-propene （HFC-1234ze）, 1- chloro-l,3,3,3-tetrafluoro-l-propene （HFC-1224zb） and 2-chloro-l,3,3,3-tetrafluoro-l-propene （HFC-1224xe） halo-olefins in the 1,1,1,3,3-pentafluoropropane （HFC-245fa] product was investigated. These halo-olefinic im- purities could be substantially removed from the HFC-245fa product via the adsorption over activated carbon when the adsorption temperature was under 333 K, which can be attributed to the n-n dispersion interactions between the halo-olefins and carbon graphite layer. The basic surface groups of activated carbon could catalyze the decomposition of HFC-245fa to form HFC-1234ze. However, the significant increase in the amount of surface acidic groups of activated carbon led to a distinct decrease of adsorption capacity due to the reduction in the mi- cropore volume of adsorbent and a decrease in the strength of the n-n dispersive interactions between halo- olefin molecules and carbon basal. The breakthrough time of halo-olefinic impurities on activated carbon in- creased with the increase of molecular mass and the decrease of molecular symmetry.展开更多
Design of high effective catalysts with unique properties opens good perspectives for solving environmental problems of cleaning waste gas, particularly from toxic impurities of organic solvents. A new thermostable na...Design of high effective catalysts with unique properties opens good perspectives for solving environmental problems of cleaning waste gas, particularly from toxic impurities of organic solvents. A new thermostable nanostructured composite materials based on shungyte was obtained and determined their adsorption capacity on the model substance o-xylene. Xylene used as a model substance is a part of the organic solvent presents in waste industrial gases. Best xylene sorbents （449.7 mg/g）--activated shungyte containing 70% carbon and saksaul charcoal （554.3 mg/g）. Then polyoxide catalysts on the base of transition metals （Ni, Mn, Cu） modified by the rare earth elements （La, Ce and Nd）, supported on a granular carrier were studied in the reaction of deep oxidation of o-xylene. 100% activity showed 7.0% Cu-Mn-Ce-catalyst at T： 250-300℃, Cxylene： 0.6 g/ms, the optimum space velocity of gas--1,200 h^1 for catalysts supported on a granular carrier. The results obtained can be used in the purification of waste gas from paint, furniture, cable, printing and other enterprises from the impurities of toxic organic solvents.展开更多
基金Projects(51464006,51164001)supported by the National Natural Science Foundation of ChinaProject(GJR201147-12)supported by Guangxi Higher Education Institutes Talent Highland Innovation Team Scheme,ChinaProject(2012MDZD038)supported by the Key Scientific Research Project of Guangxi University for Nationalities,China
文摘Six kinds of galena with different impurities were synthesized and the effects of impurities on the floatability of galena were investigated. The thermodynamic and kinetic parameters on the galena surface were measured using microcalorimetry, and the adsorption configuration and energy of butyl xanthate on the surfaces of galena with different impurities were simulated by density functional theory. Flotation experiments showed that Ag and Bi significantly promoted the recovery of galena, while Zn, Sb, Mn, and Cu reduced the recovery of the flotation. Microthermokinetic results indicated that the absolute value of xanthate adsorption heat was directly proportional to the flotation recovery of galena. Adsorption heat and reaction rate coefficients of xanthate on galena containing Ag or Bi were larger than those on pure galena, but smaller on galena containing Cu or Sb. Additionally, the relationship between the heat of unsaturated adsorption of xanthate and the adsorption energy of impurity atom on galena surface was investigated.
基金supported by the National Natural Science Foundation of China (21507130)the Open Project Program of Chongqing Key Laboratory of Environmental Materials and Remediation Technology from Chongqing University of Arts and Sciences (CEK1405)+3 种基金the Open Project Program of Beijing National Laboratory for Molecular Sciences (20140142)the Open Project Program of Jiangsu Key Laboratory of Vehicle Emissions Control (OVEC001)the Open Project Program of Chongqing Key Laboratory of Catalysis and Functional Organic Molecules from Chongqing Technology and Business University (1456029)the Chongqing Science & Technology Commission (cstc2014pt-gc20002)~~
文摘A series of CeO2‐MnOx‐Al2O3 mixed oxide catalysts （Ce：Mn：Al mole ratio=6：4：x, x=0.25, 0.5, 1, 2） were prepared by a simple one‐step inverse co‐precipitation method to investigate the influence of the incorporation of Al3＋ into CeO2‐MnOx mixed oxides. CeO2‐MnOx, CeO2‐Al2O3, and MnOx‐Al2O3 mixed oxides, and CeO2 were prepared by the same method for comparison. The samples were characterized by XRD, Raman, N2 physisorption, H2‐TPR, XPS, and in situ DRIFTS. The catalytic re‐duction of NO by CO was chosen as a model reaction to evaluate the catalytic performance. The incorporation of a small amount of Al3＋into CeO2‐MnOx mixed oxides resulted in a decrease of crys‐tallite size, with the increase of the BET specific surface area and pore volume, as well as the in‐crease of Ce3＋and Mn4＋. The former benefits good contact between catalyst and reactants, and the latter promotes the adsorption of CO and the desorption, conversion and dissociation of adsorbed NO. All these enhanced the catalytic performance for the NO＋CO model reaction. A reaction mecha‐nism was proposed to explain the excellent catalytic performance of CeO2‐MnOx‐Al2O3 catalysts for NO reduction by CO.
基金Supported by the Major Project of Green Chemical Industry of Zhejiang Province(2007C11043)
文摘Halo-olefinic impurities in 1,1,1,3,3-pentafluoropropane （HFC-245fa） product used as blowing agents, etc. could damage the human body and must be removed. Activated carbon was treated by HCI, HN03 and NaOH, respectively. The adsorptive performance of unmodified and modified activated carbons for the removal of a low con- tent of l-chloro-3,3,3-trifluoro-l-propene （HCFC-1233zd）, 1,3,3,3-tetrafluoro-l-propene （HFC-1234ze）, 1- chloro-l,3,3,3-tetrafluoro-l-propene （HFC-1224zb） and 2-chloro-l,3,3,3-tetrafluoro-l-propene （HFC-1224xe） halo-olefins in the 1,1,1,3,3-pentafluoropropane （HFC-245fa] product was investigated. These halo-olefinic im- purities could be substantially removed from the HFC-245fa product via the adsorption over activated carbon when the adsorption temperature was under 333 K, which can be attributed to the n-n dispersion interactions between the halo-olefins and carbon graphite layer. The basic surface groups of activated carbon could catalyze the decomposition of HFC-245fa to form HFC-1234ze. However, the significant increase in the amount of surface acidic groups of activated carbon led to a distinct decrease of adsorption capacity due to the reduction in the mi- cropore volume of adsorbent and a decrease in the strength of the n-n dispersive interactions between halo- olefin molecules and carbon basal. The breakthrough time of halo-olefinic impurities on activated carbon in- creased with the increase of molecular mass and the decrease of molecular symmetry.
文摘Design of high effective catalysts with unique properties opens good perspectives for solving environmental problems of cleaning waste gas, particularly from toxic impurities of organic solvents. A new thermostable nanostructured composite materials based on shungyte was obtained and determined their adsorption capacity on the model substance o-xylene. Xylene used as a model substance is a part of the organic solvent presents in waste industrial gases. Best xylene sorbents （449.7 mg/g）--activated shungyte containing 70% carbon and saksaul charcoal （554.3 mg/g）. Then polyoxide catalysts on the base of transition metals （Ni, Mn, Cu） modified by the rare earth elements （La, Ce and Nd）, supported on a granular carrier were studied in the reaction of deep oxidation of o-xylene. 100% activity showed 7.0% Cu-Mn-Ce-catalyst at T： 250-300℃, Cxylene： 0.6 g/ms, the optimum space velocity of gas--1,200 h^1 for catalysts supported on a granular carrier. The results obtained can be used in the purification of waste gas from paint, furniture, cable, printing and other enterprises from the impurities of toxic organic solvents.
