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NO adsorption and temperature programmed desorption on K_2CO_3 modified activated carbons 被引量:1
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作者 YANG Dai-jun MA Xiao-wei +2 位作者 LV Hong LI Bing ZHANG Cun-man 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第10期2339-2348,共10页
Fuel cell stacks as the automotive power source can be severely poisoned by a trace amount of NOx in atmosphere,which makes it necessary to provide clean air for fuel cell vehicles.In this work,activating commercial a... Fuel cell stacks as the automotive power source can be severely poisoned by a trace amount of NOx in atmosphere,which makes it necessary to provide clean air for fuel cell vehicles.In this work,activating commercial activated carbons with K2CO3 for the large enhancement of NO capture was studied.K2CO3 modified activated carbons(K2CO3 ACs)were prepared by impregnating activate carbons in K2CO3 solution under ultrasound treatment,followed by temperature programmed baking at 800 oC.The dynamic NO flow tests on K2CO3 ACs at room temperature indicated that NO adsorption capacity reached the maximum(96 mg/g)when K2CO3 loading was 19.5 wt%,which corresponded to a specific surface area of 1196.1 m2/g and total pore volume of 0.70 cm3/g.The ten-fold enhancement of NO adsorption on K2CO3 ACs compared to the unimpregnated activated carbon was mainly attributed to the formation of potassium nitrite,which was confirmed by FTIR and temperature programmed desorption measurements.Regeneration tests of NO adsorption on the optimum sample revealed that 76%of the NO adsorption capacity could be remained after the fourth cycle. 展开更多
关键词 activated carbon potassium carbonate MODIFICATION NO adsorption temperature programmed desorption
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THE STUDY OF THE NON-STEADY KINETICS OF THE OXYDEHYDROGENATION OF ETHANE TO ETHYLENE OVER THE CATALYST OF Mo-V-Nb/Al_2O_3 BY THE TECHNIQUE OF TEMPERATURE PROGRAMMED TRANSIENT RESPONSE AND ELECTRIC CONDUCTIVITY
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作者 Ren You ZHANG, Hong JIANG, Xiao Dong SUN Xiu Yin LIU, Fu Rong WANG, Shou Li BAI, Zong Qi XU (Department of Applied Chemistry, Beijing Institute of Chemical Technology) 100029 《Chinese Chemical Letters》 SCIE CAS CSCD 1991年第11期893-896,共4页
In this paper, instead of with the more expensive Fourier Transform Infrared Spectrometer(FTIR) a new technique of Temperature Programmed Transient Response(TP-TR) has been used with gas chromatography. Therefore, the... In this paper, instead of with the more expensive Fourier Transform Infrared Spectrometer(FTIR) a new technique of Temperature Programmed Transient Response(TP-TR) has been used with gas chromatography. Therefore, the TP-TR will be applied more widespreadly than ever before. With the technique of TP-TR and electric conductivity, the study is on the reaction mechanism and the adsorption behavior of the reactants and products to the present catalyst Mo-V-Nb/Al_2O_3 in the reaction from ethane through oxydehydrogenation to ethylene as the product. By Range-Kutta-Gill and Margarat methods, the kinetic parameters of the reaction elementary steps (i.e. rate constants, active energies and frequency factors) have been evaluated. The mathematical treatment coincides with the experimental results. 展开更多
关键词 TR THE STUDY OF THE NON-STEADY KINETICS OF THE OXYDEHYDROGENATION OF ETHANE TO ETHYLENE OVER THE CATALYST OF Mo-V-Nb/Al2O3 BY THE TECHNIQUE OF temperature programmed TRANSIENT RESPONSE AND ELECTRIC CONDUCTIVITY MO Al
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Thermodynamic study and methanothermal temperature-programmed reaction synthesis of molybdenum carbide 被引量:5
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作者 Parham Roohi Reza Alizadeh Esmaeil Fatehifar 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2016年第3期339-347,共9页
Nanostructured molybdenum carbide (Mo2C) was successfully prepared from molybdenum trioxide (MoO3) using methanothermal temperature-programmed reaction. Thermodynamic analysis indicated that in presence of methane... Nanostructured molybdenum carbide (Mo2C) was successfully prepared from molybdenum trioxide (MoO3) using methanothermal temperature-programmed reaction. Thermodynamic analysis indicated that in presence of methane, the formation of Mo2C from MoO3 occurs through the path of MoO3 → MoO2→ Mo2C. The carburized MoO3 was characterized using X-ray diffraction (XRD), CHNS/O analysis, Brunauer-Emmett-Teller (BET) analysis, and field-emission scanning electron microscopy (FESEM). At final carburization temperatures of 700 and 800℃ and at methane contents ranging from 5vol% to 20vol%, Mo2C was the only solid product observed in the XRD patterns. The re- suits indicated that the effect of methane content on the formation of the carbide phase is substantial compared with the effect of carburization time. Elemental analysis showed that at a final temperature of 700℃, the carbon content of carburized MoO3 is very close to the theoretical carbon mass percentage in Mo2C. At higher carburization temperatures, excess carbon was deposited onto the surface of Mo2C. High-surface-area Mo2C was obtained at extremely low heating rates; this high-surface-area material is a potential electrocatalyst. 展开更多
关键词 molybdenum carbide thermodynamic analysis temperature programmed reaction METHANE
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Characteristics of oxygen consumption of coal at programmed temperatures 被引量:6
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作者 QI Xuyao WANG Deming +2 位作者 ZHONG Xiaoxing GU Junjie XU Tao 《Mining Science and Technology》 EI CAS 2010年第3期372-377,共6页
Oxygen consumption is an important index of coal oxidation.In order to explore the coal-oxygen reaction,we developed an experimental system of coal spontaneous combustion and tested oxygen consumption of differently r... Oxygen consumption is an important index of coal oxidation.In order to explore the coal-oxygen reaction,we developed an experimental system of coal spontaneous combustion and tested oxygen consumption of differently ranked coals at programmed temperatures.The size of coal samples ranged from 0.18~0.42 mm and the system heat-rate was 0.8℃/min.The results show that, for high ranked coals,oxygen consumption rises with coal temperature as a piecewise non-linear process.The critical coal temperature is about 50℃.Below this temperature,oxygen consumption decreases with rising coal temperatures and reached a minimum at 50℃,approximately.Subsequently,it begins to increase and the rate of growth clearly increased with temperature.For low ranked coals,this characteristic is inconspicuous or even non-existent.The difference in oxygen consumption at the same temperatures varies for differently ranked coals.The results show the difference in oxygen consumption of the coals tested in our study reached 78.6%at 100℃.Based on the theory of coal-oxygen reaction,these phenomena were analyzed from the point of view of physical and chemical characteristics,as well as the appearance of the coal-oxygen complex.From theoretical analyses and our experiments,we conclude that the oxygen consumption at programmed temperatures reflects the oxidation ability of coals perfectly. 展开更多
关键词 oxygen consumption differently ranked coals programmed temperatures piecewise non-linear process oxidation ability
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Effect of cobalt loading on reducibility, dispersion and crystallite size of Co/Al_2O_3 Fischer-Tropsch catalyst 被引量:1
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作者 熊海峰 张煜华 +1 位作者 李金林 古映莹 《Journal of Central South University of Technology》 2004年第4期414-418,共5页
Co/Al2O3 Fischer-Tropsch synthesis catalysts with different cobalt loadings were prepared using incipient wetness impregnation method. The effects of cobalt loading on the properties of catalysts were studied by means... Co/Al2O3 Fischer-Tropsch synthesis catalysts with different cobalt loadings were prepared using incipient wetness impregnation method. The effects of cobalt loading on the properties of catalysts were studied by means of X-ray diffraction (XRD), temperature programmed reduction (TPR), hydrogen temperature programmed desorption (H2-TPD) and O2 titration. Co-support compound formation can be detected in catalyst system by XRD. For the Co/Al2O3 catalysts with low cobalt loading, CoAl2O4 phase appears visibly. Two different reduction regions can be presented for Co/Al2O3 catalysts, which belong to Co3O4 crystallites (reduction at 320 ℃) and cobalt oxide-alumina interaction species (reduction at above 400 ℃). Increasing Co loading results in the increase of Co3O4 crystallite size. The reduced Co/Al2O3 catalysts have two adsorption sites, and cobalt loading greatly influences the adsorption behavior. With the increase of cobalt loading, the amount of low temperature adsorption is increased, the amount of high temperature adsorption is decreased, and the percentage reduction and cobalt crystallite size are increased. 展开更多
关键词 Fischer-Tropsch synthesis cobalt/alumina catalyst temperature programmed reduction hydrogen temperature programmed desorption
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Surface Chemistry of Ga(CH3)3 on Pd(111) and Effect of Pre-covered H and O
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作者 丁良兵 马运生 +1 位作者 胡婕 陈博昊 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2016年第5期591-599,I0002,共10页
The adsorption and decomposition of trimethylgallium (Ga(CH3)3, TMG) on Pd(111) and the effect of pre-covered H and O were studied by temperature programmed desorption spectroscopy and X-ray photoelectron spectr... The adsorption and decomposition of trimethylgallium (Ga(CH3)3, TMG) on Pd(111) and the effect of pre-covered H and O were studied by temperature programmed desorption spectroscopy and X-ray photoelectron spectroscopy. TMG adsorbs dissociatively at 140 K and the surface is covered by a mixture of Ga(CH3)x (x=1, 2 or 3) and CHx(a) (x=1, 2 or 3) species. During the heating process, the decomposition of Ga(CH3)3 on clean Pd(111) follows a progressive Ga-C bond cleavage process with CH4 and H2 as the desorption products. The desorption of Ga-containing molecules (probably GaCH3) is also identi ed in the temperature range of 275-325 K. At higher annealing temperature, carbon deposits and metallic Ga are left on the surface and start to di use into the bulk of the substrate. The presence of precovered H(a) and O(a) has a signi cant effect on the adsorption and decomposition behavior of TMG. When the surface is pre-covered by saturated H2, CH4, and H2 desorptions are mainly observed at 315 K, which is ascribed to the dissociation of GaCH3 intermediate. In the case of O-precovered surface, the dissociation mostly occurs at 258 K, of which a Pd-O-Ga(CH3)2 structure is assumed to be the precusor. The presented results may provide some insights into the mechanism of surface reaction during the lm deposition by using trimethylgallium as precursor. 展开更多
关键词 Ga(CH3)3 Pd(lll) ADSORPTION DECOMPOSITION X-ray photoelectron spectroscopy temperature programmed desorption spectroscopy
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Modification of Surface Reactivity by CO: Effects on Decomposition and Polymerization of Acetaldehyde on Ru(0001)
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作者 陈晓 李方亮 +2 位作者 郭庆 戴东旭 杨学明 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2017年第6期643-648,I0001,共7页
The adsorption and reaction of acetaldehyde on the clean and CO pre-covered Ru(0001) surfaces have been investigated using temperature programmed desorption method. On the clean Ru(0001) surface, the decomposition... The adsorption and reaction of acetaldehyde on the clean and CO pre-covered Ru(0001) surfaces have been investigated using temperature programmed desorption method. On the clean Ru(0001) surface, the decomposition of acetaldehyde is the main reaction channel, with little polymerization occurring. However, on the CO pre-covered Ru(0001) surface, the de- composition of acetaldehyde is inhibited considerably with increasing CO coverage. Whereas, the polymerization occurs efficiently, especially at high CO coverage (θco〉0.5 ML), which is strongly CO coverage dependent. Combined with previous studies, the well-ordered hexagohal structure of CO layer formed on the Ru(0001) surface at high CO coverage that matches the configuration of paraldehyde is likely to be the origin of this remarkable phenomenon. 展开更多
关键词 ACETALDEHYDE POLYMERIZATION temperature programmed desorption Ru(0001)
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Redox behavior of gold supported on ceria and ceria-zirconia based catalysts 被引量:2
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作者 Michela Vicario Jordi Llorca +2 位作者 Marta Boaro Carla de Leitenburg Alessandro Trovarelli 《Journal of Rare Earths》 SCIE EI CAS CSCD 2009年第2期196-203,共8页
A series of gold-based catalysts were prepared by deposition precipitation or incipient wetness impregnation on CexZ1-xO2 solid solutions (0.28≤x≤1.00). The morphological and structural characterization of these c... A series of gold-based catalysts were prepared by deposition precipitation or incipient wetness impregnation on CexZ1-xO2 solid solutions (0.28≤x≤1.00). The morphological and structural characterization of these catalysts were carried out with X-ray diffraction, trans- mission electron microscopy (TEM) analysis and physical adsorption technique, and their redox properties were studied by temperature programmed reduction using both H2 and CO as probe molecules. Two cycles of oxidation/reduction were carried out in order to evaluate the effects of redox aging and gold sintering on the oxygen exchange capability. As observed with other noble metals, gold enhanced and promoted the ceria reduction at lower temperatures. Reduction by CO was shown to be dependent on the fine dispersion of gold and to be nega- tively affected by the ageing process more than reduction with hydrogen. This might have implications in reactions like water gas shift and CO-PROX which involve CO as a main reactant. 展开更多
关键词 GOLD CERIA ZIRCONIA CATALYSIS reduction behaviour nanoparticles temperature programmed reduction X-ray diffraction rare earths
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Effect of x-alumina addition on H_2S oxidation properties of pure and modified y-alumina
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作者 Svetlana A.Yashnik Vadim V.Kuznetsov Zinfer R.Ismagilov 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2018年第2期258-274,共17页
The influence of the textural and acidic properties ofγ‐Al2O3,(γ+χ)‐Al2O3,and?‐Al2O3on the catalytic activity,selectivity,and stability of direct H2S oxidation has been studied.A comparison of the H2S‐to‐S con... The influence of the textural and acidic properties ofγ‐Al2O3,(γ+χ)‐Al2O3,and?‐Al2O3on the catalytic activity,selectivity,and stability of direct H2S oxidation has been studied.A comparison of the H2S‐to‐S conversion effectiveness of aluminas with their acidic properties(identified by Fourier transform infrared spectroscopy and temperature programmed desorption of NH3)shows that H2S adsorption occurs predominantly on weak Lewis acid sites(LAS).γ‐Alumina samples containing aχ‐phase and/or modified Mg2+ions have a greater concentration of weak LAS and exhibit greater catalytic activity.When alumina is treated with a sulfuric acid solution,strong LAS appear and the number of LAS decreases significantly.Modification of alumina with hydrochloric acid has a limited effect on LAS strength.Weak LAS are retained and double in number compared to that present in the unmodified alumina,but the treated sample has Al?Cl bonds.Alumina samples modified by sulfate and chloride anions exhibit poor catalytic activity in H2S oxidation. 展开更多
关键词 ALUMINA χ‐Al2O3 Hydrogen sulfide oxidation Acidic property Lewis acid sites Fourier transform infrared spectroscopy NH3‐temperature programmed desorption
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Suppression of Photoinduced BBO Defects Generation on TIO2(110) by Water
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作者 Chen-biao Xu Wen-shao Yang +3 位作者 Qing Guo Dong-xu Dai Mao-du Chen Xue-ming Yang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2013年第6期646-650,I0003,共6页
We have investigated creation of variable concentrations of defects on TIO2(110)-(1×1) surface by 266 nm laser using temperature programmed desorption technique. Oxygen-vacancy defects can be easily induced b... We have investigated creation of variable concentrations of defects on TIO2(110)-(1×1) surface by 266 nm laser using temperature programmed desorption technique. Oxygen-vacancy defects can be easily induced by ultraviolet light, the defects concentration has a linear dependence on power density higher than 50 mW/cm2 for 90 s irradiation. No observation of O2 molecule and Ti atom desorption suggests that UV induced defects creation on TiO2(110)-(1×1) is an effective and gentle method. With pre-dosage of thin films of water, the rate of defects creation on TiO2(110)-(1×1) is slower at least by two orders of magnitude than bare TiO2(110)-(1×1) surface. Further investigations show that water can be more easily desorbed by UV light, and thus desorption of bridging oxygen is depressed. 展开更多
关键词 temperature programmed desorption Time of flight spectrum Photo- stimulated desorption Oxygen vacancy
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Effects of Surface Defects on Adsorption of CO and Methyl Groups on Rutile TiO_(2)(110)
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作者 Deng-fang Tang Xiao Chen +1 位作者 Qing Guo Wen-shao Yang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2021年第3期249-255,I0013,I0014,I0047,共10页
The interaction of reactants with catalysts has always been an important subject for catalytic reactions.As a promising catalyst with versatile applications,titania has been intensively studied for decades.In this wor... The interaction of reactants with catalysts has always been an important subject for catalytic reactions.As a promising catalyst with versatile applications,titania has been intensively studied for decades.In this work we have investigated the role of bridge bonded oxygen vacancy(O_(v))in methyl groups and carbon monoxide(CO)adsorption on rutile TiO_(2)(110)(R-TiO_(2)(110))with the temperature programmed desorption technique.The results show a clear different tendency of the desorption of methyl groups adsorbed on bridge bonded oxygen(O_(b)),and CO molecules on the five coordinate Ti^(4+)sites(Ti_(5c))as the Ovconcentration changes,suggesting that the surface defects may have crucial influence on the absorption of species on different sites of R-TiO_(2)(110). 展开更多
关键词 temperature programmed desorption TiO_(2)(110) Bridge bonded oxygen vacancy Adsorption sites Surface defects
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Surface Photocatalysis-TPD Spectrometer for Photochemical Kinetics
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作者 Ze-feng Ren Qing Guo +4 位作者 Chen-biao Xu Wen-shao Yang Chun-lei Xiao Dong-xu Dai Xue-ming Yang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2012年第5期507-512,I0003,共7页
A surface photocatalysis-TPD apparatus devoted to studying kinetics and mechanism of pho- tocatalytic processes with various signal crystal surfaces has been constructed. Extremely high vacuum (-0.2 nPa) in the ioni... A surface photocatalysis-TPD apparatus devoted to studying kinetics and mechanism of pho- tocatalytic processes with various signal crystal surfaces has been constructed. Extremely high vacuum (-0.2 nPa) in the ionization region is obtained by using multiple ultrahigh vacuum pumps. Compared with similar instruments built previously by others~ the H2, CH4 background in the ionization region can be reduced by about two orders of magnitude, and other residual gases in the ionization region can be reduced by about an order of magnitude. Therefore, the signal-to-noise ratio for the temperature programmed desorption (TPD) and time of flight (TOF) spectra is substantially enhanced, making experimental studies of pho- tocatalytic processes on surfaces much easier. In this work, we describe the new apparatus in detail and present some preliminary studies on the photo-induced oxygen vacancy defects on TiO2(110) at 266 nm by using the TPD and TOF methods. Preliminary results suggest that the apparatus is a powerful tool for studying kinetics and mechanism of photochemical processes. 展开更多
关键词 temperature programmed desorption Time of flight spectrum Surface pho-tochemical kinetics
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Correlation between Iron Reducibility in Natural and Iron-Modified Clays and Its Adsorptive Capability for Arsenic Removal
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作者 Irma Lia Botto Simonetta Tuti +1 位作者 María Jose Gonzalez Delia Gazzoli 《Advances in Materials Physics and Chemistry》 2016年第5期129-139,共11页
The study reports aspects that allowed to correlate structural and redox properties of iron species deposited on clay minerals with the capacity of geomaterials for arsenic removal. Natural ferruginous clays as well a... The study reports aspects that allowed to correlate structural and redox properties of iron species deposited on clay minerals with the capacity of geomaterials for arsenic removal. Natural ferruginous clays as well as an iron-poor clay chemically modified with Fe(III) salt (ferrihydrite species) were investigated as adsorbents of the arsenate(V) in water. The study, carried out from minerals from abundant Argentinean deposits, was conducted with the aid of different techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM-EDS), Raman Spectroscopy, ICP-AES (Inductively Coupled Plasma) chemical analysis and Temperature Programmed Reduction (TPR). This last technique allowed to detect availability of iron species in oxidic environment with different structural complexity and to determine active sites, accessible for arsenate(V) adsorption. The effect was observed through temperature dependence of the first Fe(III) reduction step (below 570&deg;C) of iron-oxide species. The sequence of reducibility: ferrihydrite > hydrous oxide (goethite) > anhydrous oxide (hematite) > structural iron in clay was in agreement with the availability of iron active sites for the reducing process as well as for the arsenate adsorption. The important role of very high iron content in original samples was also observed. The chemical activation of iron-poor clay by a simple and feasible modification with Fe(III) solutions promoted the deposition of the ferrihydrite active phase with an increase of 2.81% (expressed as Fe2O3) respect to the original content of 1.07%, constituting an accessible and eco-friendly technological alternative to solve the environmental problem of water containing arsenic. 展开更多
关键词 temperature programmed Reduction Iron-Oxide Species Arsenic Removal
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Surface Acidity of Aluminum Phosphate and Its Catalytic Performance in Benzene Alkylation with Long Chain Olefin 被引量:2
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作者 YUAN Haikuan LIU Xuru REN Jie SHEN Lian 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2013年第6期627-632,共6页
The acidic properties of aluminum phosphate (A1PO4-5) solid acid catalyst were characterized by tem- perature programmed desorption (TPD) of ammonia (NH3), n-propylamine (n-C3HTNH2), iso-propylamine [(CH3)2C... The acidic properties of aluminum phosphate (A1PO4-5) solid acid catalyst were characterized by tem- perature programmed desorption (TPD) of ammonia (NH3), n-propylamine (n-C3HTNH2), iso-propylamine [(CH3)2CHNH2] and n-dipropylamine [(C3H7)2NH] separately, and its catalytic performance in benzene alkylation with long chain olefin was studied in a fixed-bed reactor. The characterized acid amount of catalyst increased with the basicity of adsorbates. With increase of the activation temperature of catalyst, the acid amount characterized by NHa-TPD decreased, however, it increased when characterized by TPD using three other adsorbates. The desorption kinetics of TPD process and the deactivation kinetics of catalyst were investigated. The acidity and catalytic per- formance of catalyst was also correlated. The results showed that the acid amount and strength are well correlated with the activity and stability using NH3 as adsorbate, respectively, which indicated NH3 was a better basic adsorbate. It was also found that the catalyst with higher acid amount and lower acid strength on the surface exhibited the better catalytic performance and stability. 展开更多
关键词 suuface acidity temperatureprogrammed desorption basic adsorbate benzene alkylation catalytic activity
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Ru/FeO_x catalyst performance design: Highly dispersed Ru species for selective carbon dioxide hydrogenation 被引量:2
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作者 Di Zhang Jingjie Luo +5 位作者 Jiajie Wang Xin Xiao Yuefeng Liu Wei Qi Dang Sheng Su Wei Chu 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2018年第1期157-166,共10页
A series of Ru/FeOx catalysts were synthesized for the selective hydrogenation of CO2to CO.Detailed characterizations of the catalysts through X‐ray diffraction,X‐ray photoelectron spectroscopy,transmission electron... A series of Ru/FeOx catalysts were synthesized for the selective hydrogenation of CO2to CO.Detailed characterizations of the catalysts through X‐ray diffraction,X‐ray photoelectron spectroscopy,transmission electron microscopy,and temperature‐programmed techniques were performed to directly monitor the surface chemical properties and the catalytic performance to elucidate the reaction mechanism.Highly dispersed Ru species were observed on the surface of FeOx regardless of the initial Ru loading.Varying the Ru loading resulted in changes to the Ru coverage over the FeOx surface,which had a significant impact on the interaction between Ru and adsorbed H,and concomitantly,the H2activation capacity via the ability for H2dissociation.FeOx having0.01%of Ru loading exhibited100%selectivity toward CO resulting from the very strong interaction between Ru and adsorbed H,which limits the desorption of the activated H species and hinders over‐reduction of CO to CH4.Further increasing the Ru loading of the catalysts to above0.01%resulted in the adsorbed H to be easily dissociated,as a result of a weaker interaction with Ru,which allowed excessive CO reduction to produce CH4.Understanding how to selectively design the catalyst by tuning the initial loading of the active phase has broader implications on the design of supported metal catalysts toward preparing liquid fuels from CO2.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences toward preparing liquid fuels from CO2.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved. 展开更多
关键词 Highly dispersed Ru/FeOx catalyst temperatureprogrammed surface reaction CO2 selective hydrogenation Product selectivity Hydrogen adsorption
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Characterization and Preparation of Ce-Zr-O Solid Solution 被引量:1
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作者 罗孟飞 周碧 +3 位作者 林瑞 陈敏 袁贤鑫 郑小明 《Journal of Rare Earths》 SCIE EI CAS CSCD 2000年第4期275-278,共4页
Ce Zr O solid solution was prepared by four different methods, i.e., decomposition of nitrate, coprecipiation, hydroxysuainic acid sol gel as well as citrate sol gel, and characterized by using X ray powder diffr... Ce Zr O solid solution was prepared by four different methods, i.e., decomposition of nitrate, coprecipiation, hydroxysuainic acid sol gel as well as citrate sol gel, and characterized by using X ray powder diffraction, Raman and temperature programmed reduction. The phase composition and the reduction properties of Ce Zr O depend on the preparation method. A cubic Ce 0.5 Zr 0.5 O 2 solid solution can be obtained by using the sol gel method. The Ce Zr O solid solution prepared by using decomposition or coprecipiation was composed of cubic Ce 0.8 Zr 0.2 O 2 and tetragonal Ce 0.2 Zr 0.8 O 2 solid solution. The Ce Zr O solid solution prepared with different methods shows the different reduction properties owing to different phase composition. Results of differential thermal analysis and XRD show that Ce 0.5 Zr 0.5 O 2 solid solution is formed during the decomposition or combustion of the gel. 展开更多
关键词 rare earths Ce 0.5 Zr 0.5 O 2 solid solution X ray powder diffraction RAMAN temperature programmed reduction
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Effects of Coated Capillary Column, Derivatization, and Temperature Programming on the Identification of Carica papaya Seed Extract Composition Using GC/MS Analysis
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作者 Muhamad Shirwan Abdullah Sani Jamilah Bakar +1 位作者 Russly Abdul Rahman Faridah Abas 《Journal of Analysis and Testing》 EI 2020年第1期23-34,共12页
Some of the common practices to assess the composition of plant extract,including Carica papaya seed extract(CPSE)are direct injection of the extract,compound separation using polyethylene glycol capillary column(DB-W... Some of the common practices to assess the composition of plant extract,including Carica papaya seed extract(CPSE)are direct injection of the extract,compound separation using polyethylene glycol capillary column(DB-WAX),and non-linear-temperature programming(NLTP)of GC/MS analysis.This study specifically compared the coating of capillary column,sample derivatization,and temperature programming of GC/MS to determine the composition of CPSE.The retention indices(RI)of the detected compounds were determined and compared to the reference RI.In particular,5%phenyl-95%methylpolysiloxane(HP-5MS)-,DB-WAX-,and biscyanopropyl polysiloxane(HP-88)-coated capillary columns were used to identify the composition of CPSE.For this study,HP-5MS column,which separated the highest number of compounds(26 compounds)from CPSE,was deemed as the most suitable column.The GC/MS analysis of derivatized CPSE identified 21 compound groups,where fatty acids and fatty acid methyl esters served as the major compounds(80.23%),followed by these compounds in decreasing order:amides>nitriles>sterols>fatty aldehydes>organic acids.A stronger correlation determination between the carbon number and alkane retention time of linear-temperature programming(LTP)(R^(2)=0.9859)was found,as compared to its correlation determination with NLTP(R^(2)=0.9175),which exhibited an almost equal RI of LTP to the reference RI.Conclusively,GC/MS analysis for the derivatized CPSE using HP-5MS column separation and LTP is highly recommended. 展开更多
关键词 Capillary column Carica papaya seed GC/MS Sample derivatization temperature programming
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Temperature self-adaptive program algorithm on 65nm MLC NOR flash memory
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作者 史维华 洪志良 +1 位作者 胡潮红 亢勇 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2009年第8期160-163,共4页
This paper presents an implementation for improving muti-level cell NOR flash memory program through-put based on the channel hot electron (CHE) temperature characteristic. The CHE Ig temperature characteristic is a... This paper presents an implementation for improving muti-level cell NOR flash memory program through-put based on the channel hot electron (CHE) temperature characteristic. The CHE Ig temperature characteristic is analyzed theoretically with the Lucky electron model, and a temperature self-adaptive programming algorithm is proposed to increase Ig according to the on-die temperature. Experimental results show that the program throughput increases significantly from 1.1 MByte/s without temperature self-adaptive programming to 1.4 MByte/s with the proposed method at room temperature. This represents a 30% improvement and is 70 times faster than the program throughput in Ref. [1]. 展开更多
关键词 temperature self-adaptive programming 65 nm multi-level cell flash memory program throughput
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N2O Decomposition Catalyzed by K+-doped Bi0.02Co
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作者 TURSUN Mamutj an WANG Bingshuai +3 位作者 JIANG Yan YU Haibiao SUN Xingtao WANG Xinping 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2016年第3期418-422,共5页
K+-doped Bi0.02Co was investigated as catalyst for N2O decomposition. It was found that the catalytic performance of the Bi0.02Co catalyst, which was prepared by coprecipitation method, can be effectively modified by... K+-doped Bi0.02Co was investigated as catalyst for N2O decomposition. It was found that the catalytic performance of the Bi0.02Co catalyst, which was prepared by coprecipitation method, can be effectively modified by potassium cations via impregnation. The optimized K0.01Bi0.02Co catalyst exhibited much higher activity compared with Bi0.02Co and K0.01Co for the reaction in feed gas 0.2% N2O/Ar, irrespective of the presence or absence of impurity gas(volume fraction) 5%02, 2%H20, 0.12%NO and 10%CO2. Characterization of the catalysts with H2 temperature programmed reduction(H2-TPR) and O2 temperature programmed desorption(O2-TPD) indicate that the Co--O bond in Bi0.02Co was weakened by the K+ doping, and hence the K0.01Bi0.02Co catalyst has much higher turnover frequency(TOF) than CO3O4 spinel and Bi0.02Co for the reaction. 展开更多
关键词 N2O Turnover frequency Reaction order H2 temperature programmed reduction O2 temperature programmed desorption
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