在小型流化床反应器中,在常压,210～250℃,流化气速0.04 m/s 的条件下,采用工业用NC-1000型氧氯化催化剂进行催化 C_2H_4燃烧副反应的宏观动力学实验。采用幂函数型动力学方程建立了C_2H_4燃烧反应动力学模型,采用改进的高斯-牛顿法回...在小型流化床反应器中,在常压,210～250℃,流化气速0.04 m/s 的条件下,采用工业用NC-1000型氧氯化催化剂进行催化 C_2H_4燃烧副反应的宏观动力学实验。采用幂函数型动力学方程建立了C_2H_4燃烧反应动力学模型,采用改进的高斯-牛顿法回归模型参数,并进行残差分析和统计检验。结果表明,所得到的反应器出口 C_2H_4的摩尔分率的动力学模型计算值与实验数据吻合良好,可以为乙烯氧氯化流化床反应器的放大设计和模型化提供理论依据。展开更多
LaMnO3was prepared by citrate sol‐gel,coprecipitation,hard template,and hydrothermal methods,respectively,and its catalytic performance for the combustion of vinyl chloride was investigated.N2adsorption‐desorption,X...LaMnO3was prepared by citrate sol‐gel,coprecipitation,hard template,and hydrothermal methods,respectively,and its catalytic performance for the combustion of vinyl chloride was investigated.N2adsorption‐desorption,X‐ray diffraction(XRD),Raman spectroscopy(Raman),O2temperature programmed desorption(O2‐TPD),H2temperature programmed surface reaction(H2‐TPR)and X‐ray photoelectron spectroscopy(XPS)were used to characterize the physicochemical properties of the LaMnO3samples.The preparation methods had obvious effects on the distribution of oxygen and manganese species on the catalyst surface.The reaction followed the suprafacial mechanism;the activity corresponded with the high amount of Mn4+and adsorbed oxygen species.LaMnO3prepared by the citrate sol‐gel method had the best performance for vinyl chloride combustion with T90of182°C.The optimal activity was attributed to the improved redox capability of Mn4+/Mn3+.More available adsorbed oxygen and Mn4+species on the surface were mainly responsible for the remarkable enhancement of the catalytic activity.展开更多
Catalysts CuOx/γ,-Al2O3-IH and CuOx/γ/-Al2O3-IM were prepared, characterized, and tested for styrene combustion in the absence and presence of water vapor. The effect of copper valence of the catalysts on the cataly...Catalysts CuOx/γ,-Al2O3-IH and CuOx/γ/-Al2O3-IM were prepared, characterized, and tested for styrene combustion in the absence and presence of water vapor. The effect of copper valence of the catalysts on the catalytic activity for styrene combustion was discussed using the theory of hard soft acids and bases （HSAB）. The results showed that the existence of water vapor in feed stream inhibited the catalytic activity for styrene combustion due to the competition adsorption of water molecule. HSAB theory confirmed that the local soft acidity of the catalyst CuOx/^-AI203-1H was much stronger than that of the catalyst CuOx/^-AI203-1M because of the higher content of soft acid Cu＋ on its surface, which increased the adsorption ability toward soft base of styrene and reduced the adsorption toward hard base of water vapor, and thus increased the catalytic activity for styrene combustion and weakened the negative influence of water vapor.展开更多
The formation of the aromatic ring during the formation of polycyclic aromatic hydrocarbons (PAHs) remains controversial and the experimental evidence is still lacking. Moreover, the formation mechanism of benzene fro...The formation of the aromatic ring during the formation of polycyclic aromatic hydrocarbons (PAHs) remains controversial and the experimental evidence is still lacking. Moreover, the formation mechanism of benzene from acetylene in the gas phase has also puzzled organic chemists for decades. Here, ab initio molecular dynamics simulations and electronic structure calculations provide compelling evidence for an unexpected competitive reaction pathway in which the aromatic ring is formed through successive additions of vinylidene. Moreover, no collisions cause bond dissociation of the acetylene molecule during the formation of benzene in this work. This study reveals the key role for the vinylidene carbene and determines the lifetime of vinylidene.展开更多
Cu-ZSM-5 molecular sieves were prepared by the ion-exchange of NH4-ZSM-5 with Cu^2＋ ions in Cu（NO3）2 solution, and was characterized by diffuse reflectance ultraviolet-visible spectroscopy （DRS-UV-vis）, fourier t...Cu-ZSM-5 molecular sieves were prepared by the ion-exchange of NH4-ZSM-5 with Cu^2＋ ions in Cu（NO3）2 solution, and was characterized by diffuse reflectance ultraviolet-visible spectroscopy （DRS-UV-vis）, fourier transform infrared spectroscopy （FT-IR） and X-ray powder diffraction （XRD） techniques. And at same time, the catalytic activity of the obtained Cu-ZSM-5 in the trichloroethylene （TCE） combustion with air in the fixed-bed system was also investigated in the present work. The results indicated that the copper content in Cu-ZSM-5 was increased with the increasing Cu2＋ concentration in ion-exchange solution, and however the catalytic activity was not always increased with the copper content in Cu-ZSM-5. It was found that Cu-ZSM-5, prepared with 0.091mol/L of Cu^2＋ solution, exhibited the best catalytic activity in TCE combustion. In combination with the characterization results by DRS-UV-vis and FT-IR techniques, it was deduced that the catalytic active species of Cu-ZSM-5 in TCE combustion with air was the skeletal copper of molecular sieves.展开更多
Coal samples in the air for three months were characterized by Thermogravimetric Analysis (TGA). The effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal was examined. The moisture loss acti...Coal samples in the air for three months were characterized by Thermogravimetric Analysis (TGA). The effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal was examined. The moisture loss activation energy, oxidation activation energy and combustion activation energy were calculated by an integral method using the Coats-Redfen formula. The results show that the tendency for spontaneous combustion of three coal samples (judged by the activation energy) falls in the order: CYW>YJL>SW. The oxidation activation energy and combustion activation energy of coal protected by the PVA oxygen-insulating barrier increased. A significant increase in the combustion activation energy was noted, especially for the CYW coal where the in-crease was 28.53 kJ/mol. Hence, oxidation of the protected coal samples was more difficult. The PVA oxygen-insulating barrier helps to prevent spontaneous combustion of the coal.展开更多
To better understand potential pollutant formations during combustion of conventional hydrocarbon fuels blended with oxygenated fuels, detailed influences of ethanol as fuel additive on small polycyclic aromatic hydro...To better understand potential pollutant formations during combustion of conventional hydrocarbon fuels blended with oxygenated fuels, detailed influences of ethanol as fuel additive on small polycyclic aromatic hydrocarbons(PAHs) precursors, aldehydes, ketene and other important intermediate species in premixed fuel-rich low-pressure ethylene flames are distinguished among dilution, thermal and chemical effects of additives. Dominant effects of ethanol addition on each species are underlined respectively. Ethylene oxidation process is delayed when ethylene is substituted by ethanol. The influence of ethanol dilution and thermal effects on ethylene consumption are larger than chemical effects. CO mole fractions slightly decrease mainly as a result of dilution and thermal effects of added ethanol. The reductions in small PAHs precursors(acetylene and propargyl) are attributed to dilution and thermal effects of ethanol addition instead of chemical effects. The ethanol chemical effects promote formations of hazardous pollutants formaldehyde and acetaldehyde, and especially are responsible for the significant increase of acetaldehyde. C2H6, C4H2 and C4H4 mole fractions decrease in a similar way with acetylene and propargyl as ethanol is added. Ethanol used here only serves as a prototype of oxygenated additive, and identification method in this work is more universal which can be easily extended for analyzing other fuel blends of hydrocarbon and oxygenated fuels.展开更多
文摘在小型流化床反应器中,在常压,210～250℃,流化气速0.04 m/s 的条件下,采用工业用NC-1000型氧氯化催化剂进行催化 C_2H_4燃烧副反应的宏观动力学实验。采用幂函数型动力学方程建立了C_2H_4燃烧反应动力学模型,采用改进的高斯-牛顿法回归模型参数,并进行残差分析和统计检验。结果表明,所得到的反应器出口 C_2H_4的摩尔分率的动力学模型计算值与实验数据吻合良好,可以为乙烯氧氯化流化床反应器的放大设计和模型化提供理论依据。
基金supported by the National Basic Research Program of China (2013CB933201)the National Natural Science Foundation of China (21207037,21577035)the Commission of Science and Technology of Shanghai Municipality (15DZ1205305)~~
文摘LaMnO3was prepared by citrate sol‐gel,coprecipitation,hard template,and hydrothermal methods,respectively,and its catalytic performance for the combustion of vinyl chloride was investigated.N2adsorption‐desorption,X‐ray diffraction(XRD),Raman spectroscopy(Raman),O2temperature programmed desorption(O2‐TPD),H2temperature programmed surface reaction(H2‐TPR)and X‐ray photoelectron spectroscopy(XPS)were used to characterize the physicochemical properties of the LaMnO3samples.The preparation methods had obvious effects on the distribution of oxygen and manganese species on the catalyst surface.The reaction followed the suprafacial mechanism;the activity corresponded with the high amount of Mn4+and adsorbed oxygen species.LaMnO3prepared by the citrate sol‐gel method had the best performance for vinyl chloride combustion with T90of182°C.The optimal activity was attributed to the improved redox capability of Mn4+/Mn3+.More available adsorbed oxygen and Mn4+species on the surface were mainly responsible for the remarkable enhancement of the catalytic activity.
基金Supported by the National Natural Science Foundation of China(21366008)the Foundation of Guizhou University((2010)040)the Science & Technology Foundation of Guizhou Province((2012)2152)
文摘Catalysts CuOx/γ,-Al2O3-IH and CuOx/γ/-Al2O3-IM were prepared, characterized, and tested for styrene combustion in the absence and presence of water vapor. The effect of copper valence of the catalysts on the catalytic activity for styrene combustion was discussed using the theory of hard soft acids and bases （HSAB）. The results showed that the existence of water vapor in feed stream inhibited the catalytic activity for styrene combustion due to the competition adsorption of water molecule. HSAB theory confirmed that the local soft acidity of the catalyst CuOx/^-AI203-1H was much stronger than that of the catalyst CuOx/^-AI203-1M because of the higher content of soft acid Cu＋ on its surface, which increased the adsorption ability toward soft base of styrene and reduced the adsorption toward hard base of water vapor, and thus increased the catalytic activity for styrene combustion and weakened the negative influence of water vapor.
基金supported by the National Natural Science Foundation of China(No.21403221 and No.91441106)
文摘The formation of the aromatic ring during the formation of polycyclic aromatic hydrocarbons (PAHs) remains controversial and the experimental evidence is still lacking. Moreover, the formation mechanism of benzene from acetylene in the gas phase has also puzzled organic chemists for decades. Here, ab initio molecular dynamics simulations and electronic structure calculations provide compelling evidence for an unexpected competitive reaction pathway in which the aromatic ring is formed through successive additions of vinylidene. Moreover, no collisions cause bond dissociation of the acetylene molecule during the formation of benzene in this work. This study reveals the key role for the vinylidene carbene and determines the lifetime of vinylidene.
文摘Cu-ZSM-5 molecular sieves were prepared by the ion-exchange of NH4-ZSM-5 with Cu^2＋ ions in Cu（NO3）2 solution, and was characterized by diffuse reflectance ultraviolet-visible spectroscopy （DRS-UV-vis）, fourier transform infrared spectroscopy （FT-IR） and X-ray powder diffraction （XRD） techniques. And at same time, the catalytic activity of the obtained Cu-ZSM-5 in the trichloroethylene （TCE） combustion with air in the fixed-bed system was also investigated in the present work. The results indicated that the copper content in Cu-ZSM-5 was increased with the increasing Cu2＋ concentration in ion-exchange solution, and however the catalytic activity was not always increased with the copper content in Cu-ZSM-5. It was found that Cu-ZSM-5, prepared with 0.091mol/L of Cu^2＋ solution, exhibited the best catalytic activity in TCE combustion. In combination with the characterization results by DRS-UV-vis and FT-IR techniques, it was deduced that the catalytic active species of Cu-ZSM-5 in TCE combustion with air was the skeletal copper of molecular sieves.
基金support provided by the National Natural Science Foundation of China (No20807056)the Research Fund for the Doctoral Program of Higher Education of China (No20060290506)the Foundation of China University of Mining & Technology (Nos0H060097 and 0H080254)
文摘Coal samples in the air for three months were characterized by Thermogravimetric Analysis (TGA). The effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal was examined. The moisture loss activation energy, oxidation activation energy and combustion activation energy were calculated by an integral method using the Coats-Redfen formula. The results show that the tendency for spontaneous combustion of three coal samples (judged by the activation energy) falls in the order: CYW>YJL>SW. The oxidation activation energy and combustion activation energy of coal protected by the PVA oxygen-insulating barrier increased. A significant increase in the combustion activation energy was noted, especially for the CYW coal where the in-crease was 28.53 kJ/mol. Hence, oxidation of the protected coal samples was more difficult. The PVA oxygen-insulating barrier helps to prevent spontaneous combustion of the coal.
基金supported by the National Natural Science Foundation of China(Grant No.51306091)the Jiangsu Provincial Natural Science Foundation of China(Grant Nos.BK20140034,BK20130758)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.30920140111005)the Jiangsu Provincial Project of"Six Talent Summit"(Grant No.2014-XNY-002)
文摘To better understand potential pollutant formations during combustion of conventional hydrocarbon fuels blended with oxygenated fuels, detailed influences of ethanol as fuel additive on small polycyclic aromatic hydrocarbons(PAHs) precursors, aldehydes, ketene and other important intermediate species in premixed fuel-rich low-pressure ethylene flames are distinguished among dilution, thermal and chemical effects of additives. Dominant effects of ethanol addition on each species are underlined respectively. Ethylene oxidation process is delayed when ethylene is substituted by ethanol. The influence of ethanol dilution and thermal effects on ethylene consumption are larger than chemical effects. CO mole fractions slightly decrease mainly as a result of dilution and thermal effects of added ethanol. The reductions in small PAHs precursors(acetylene and propargyl) are attributed to dilution and thermal effects of ethanol addition instead of chemical effects. The ethanol chemical effects promote formations of hazardous pollutants formaldehyde and acetaldehyde, and especially are responsible for the significant increase of acetaldehyde. C2H6, C4H2 and C4H4 mole fractions decrease in a similar way with acetylene and propargyl as ethanol is added. Ethanol used here only serves as a prototype of oxygenated additive, and identification method in this work is more universal which can be easily extended for analyzing other fuel blends of hydrocarbon and oxygenated fuels.
