为进一步提高FTIR光谱法实现特征吸收光谱严重重叠的甲烷、乙烷、丙烷、异丁烷、正丁烷、异戊烷以及正戊烷七组分混合气体定量分析的精度和速度,提出一种核偏最小二乘(Kernel Partial Least Square,KPLS)特征提取耦合支持向量回归机(Sup...为进一步提高FTIR光谱法实现特征吸收光谱严重重叠的甲烷、乙烷、丙烷、异丁烷、正丁烷、异戊烷以及正戊烷七组分混合气体定量分析的精度和速度,提出一种核偏最小二乘(Kernel Partial Least Square,KPLS)特征提取耦合支持向量回归机(Support Vector Regression Machine,SVR)的红外光谱定量分析新方法.首先采用KPLS方法对上述七组分混合气体的FTIR光谱进行特征提取,然后将特征提取得到的特征组分作为SVR的输入建立混合气体的定量分析模型.对标准混合气体进行定量分析的结果显示:KPLS-SVR模型的预测精度高于未进行特征提取SVR模型预测的精度,同时预测时间也减少了一半.研究表明,KPLS法可以很好地提取隐含在混合气体FTIR光谱数据与其组分浓度之间的非线性特征并有效地消除光谱数据噪声,大幅度降低数据维数,与SVR耦合可以提高红外光谱分析的精度和速度,是一种有效的红外光谱定量分析方法.展开更多
The effect of the modification of an alumina support with chloride on the structure and the catalytic performance of Ag/Al_(2)O_(3)catalysts(SA)was investigated for the selective catalytic reduction(SCR)of NO using C_...The effect of the modification of an alumina support with chloride on the structure and the catalytic performance of Ag/Al_(2)O_(3)catalysts(SA)was investigated for the selective catalytic reduction(SCR)of NO using C_(3)H_(6)or H_(2)/C_(3)H_(6)as reductants.The Ag/Al_(2)O_(3)catalyst and Cl^(–)-modified Ag/Al_(2)O_(3)catalysts(SA-Cl)were prepared by a conventional impregnation method and characterized by X-ray diffraction,Brunauer-Emmett-Teller isotherm analysis,electron probe microanalysis,transmission electron microscopy,UV-Vis diffuse reflectance spectroscopy,X-ray photoelectron spectroscopy,and hydrogen temperature-programmed reduction.The catalytic activities in the C3H6-SCR and H_(2)/C3H6-SCR reactions were evaluated,and the reaction mechanism was studied using in situ diffuse reflectance infrared Fourier transform spectroscopy and synchrotron vacuum ultraviolet photoionization mass spectroscopy(SVUV-PIMS).We found that Cl^(-)modification of the alumina-supported Ag/Al_(2)O_(3)catalysts facilitated the formation of oxidized silver species(Ag_(n)^(ᵟ+))that catalyze the moderate-temperature oxidation of hydrocarbons into partial oxidation products(mainly acetate species)capable of participating in the SCR reaction.The low-temperature promoting effect of H_(2)on the C3H6-SCR("hydrogen effect")was found to originate from the enhanced decomposition of strongly adsorbed nitrates on the catalyst surface and the conversion of these adsorbed species to–NCO and–CN species.This"H_(2)effect"occurs in the presence of Ag_(n)^(ᵟ+)species rather than the metallic Ag^(0)species.A gaseous intermediate,acrylonitrile(CH_(2)CHCN),was also identified in the H_(2)/C3H6-SCR reaction using SVUV-PIMS.These findings provide novel insights in the structure-activity relationship and reaction mechanisms of the SA-catalyzed HC-SCR reaction of NO.展开更多
In situ studies of catalysts play valuable roles in observing phase transformation, understanding the corresponding surface chemistry and the mechanism of the reaction. In this paper, ceria promoted cobalt oxide was p...In situ studies of catalysts play valuable roles in observing phase transformation, understanding the corresponding surface chemistry and the mechanism of the reaction. In this paper, ceria promoted cobalt oxide was prepared by the calcination method and investigated for the CO oxidation. The microstructure and morphology of CeO2-Co3O4 were investigated by the Scanning Electron Microscope, High-resolution transmission electron microscopy, Raman and X-ray photoelectron spectroscopy characterization. The effect of CeO2 doping on Co3O4 for CO oxidation was characterized by in situ X-ray Diffraction (in situ XRD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). In situ XRD was carried out under H2 atmosphere to evaluate the redox property of catalysts. The results indicated that the ceria doping can enhance the reducibility of Co2+ and promote the Co3+-Co2+-Co3+ cycle, owing to the oxygen replenish property of CeO2. Furthermore, adsorbed carbonate species on the surface of CeO2-Co3O4 were investigated by in situ-DRIFTS experiment. It was turned out that carbonate species on ceria promoted cobalt oxide catalysts showed different IR peaks compared with pure cobalt oxide. The carbonate species on ceria promoted catalyst are more active, and similar to free state carbonate species with weak bonding to catalyst surface, which can effectively inhibit catalyst inactivation. This study revealed the mechanism of ceria promoting CO oxidation over cobalt oxide, which will provide theoretical support for the design of efficient CO oxidation catalysts.展开更多
文摘The effect of the modification of an alumina support with chloride on the structure and the catalytic performance of Ag/Al_(2)O_(3)catalysts(SA)was investigated for the selective catalytic reduction(SCR)of NO using C_(3)H_(6)or H_(2)/C_(3)H_(6)as reductants.The Ag/Al_(2)O_(3)catalyst and Cl^(–)-modified Ag/Al_(2)O_(3)catalysts(SA-Cl)were prepared by a conventional impregnation method and characterized by X-ray diffraction,Brunauer-Emmett-Teller isotherm analysis,electron probe microanalysis,transmission electron microscopy,UV-Vis diffuse reflectance spectroscopy,X-ray photoelectron spectroscopy,and hydrogen temperature-programmed reduction.The catalytic activities in the C3H6-SCR and H_(2)/C3H6-SCR reactions were evaluated,and the reaction mechanism was studied using in situ diffuse reflectance infrared Fourier transform spectroscopy and synchrotron vacuum ultraviolet photoionization mass spectroscopy(SVUV-PIMS).We found that Cl^(-)modification of the alumina-supported Ag/Al_(2)O_(3)catalysts facilitated the formation of oxidized silver species(Ag_(n)^(ᵟ+))that catalyze the moderate-temperature oxidation of hydrocarbons into partial oxidation products(mainly acetate species)capable of participating in the SCR reaction.The low-temperature promoting effect of H_(2)on the C3H6-SCR("hydrogen effect")was found to originate from the enhanced decomposition of strongly adsorbed nitrates on the catalyst surface and the conversion of these adsorbed species to–NCO and–CN species.This"H_(2)effect"occurs in the presence of Ag_(n)^(ᵟ+)species rather than the metallic Ag^(0)species.A gaseous intermediate,acrylonitrile(CH_(2)CHCN),was also identified in the H_(2)/C3H6-SCR reaction using SVUV-PIMS.These findings provide novel insights in the structure-activity relationship and reaction mechanisms of the SA-catalyzed HC-SCR reaction of NO.
基金supported by the State Key Research Development Program of China(2016YFA0204200)the National Natural Science Foundation of China(21822603,21577036,21773062)+3 种基金the Shanghai Pujiang Program(17PJD011)the Zhejiang public welfare technology research plan/rural agriculture(LGN18B010001)the Zhejiang provincial Collaborative Innovation Center of Agricultural Biological Resources Biochemical Manufacturing(NO:2016KF0005)the scientific research project of Zhejiang provincial education department(Y201839892)~~
文摘In situ studies of catalysts play valuable roles in observing phase transformation, understanding the corresponding surface chemistry and the mechanism of the reaction. In this paper, ceria promoted cobalt oxide was prepared by the calcination method and investigated for the CO oxidation. The microstructure and morphology of CeO2-Co3O4 were investigated by the Scanning Electron Microscope, High-resolution transmission electron microscopy, Raman and X-ray photoelectron spectroscopy characterization. The effect of CeO2 doping on Co3O4 for CO oxidation was characterized by in situ X-ray Diffraction (in situ XRD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). In situ XRD was carried out under H2 atmosphere to evaluate the redox property of catalysts. The results indicated that the ceria doping can enhance the reducibility of Co2+ and promote the Co3+-Co2+-Co3+ cycle, owing to the oxygen replenish property of CeO2. Furthermore, adsorbed carbonate species on the surface of CeO2-Co3O4 were investigated by in situ-DRIFTS experiment. It was turned out that carbonate species on ceria promoted cobalt oxide catalysts showed different IR peaks compared with pure cobalt oxide. The carbonate species on ceria promoted catalyst are more active, and similar to free state carbonate species with weak bonding to catalyst surface, which can effectively inhibit catalyst inactivation. This study revealed the mechanism of ceria promoting CO oxidation over cobalt oxide, which will provide theoretical support for the design of efficient CO oxidation catalysts.
