Amorphous Ni B/γ Al 2O 3 catalyst 1 is prepared with chemical reduction by KBH 4 solution after wetness impregnation and desiccation at 70 ℃ first and then at 110 ℃ for thorough water removal. Its higher catalytic ...Amorphous Ni B/γ Al 2O 3 catalyst 1 is prepared with chemical reduction by KBH 4 solution after wetness impregnation and desiccation at 70 ℃ first and then at 110 ℃ for thorough water removal. Its higher catalytic activity than amorphous Ni B/γ Al 2O 3 catalyst 2, prepared by conventional one step desiccation procedure at 110 ℃, is identified in liquid phase benzene hydrogenation to cyclohexane. Both catalysts are characterized by XRD and SEM, Ni B/γ Al 2O 3 catalyst 1 has a higher active specific surface area and dispersion degree, which can be assigned to more effective distribution of nickel salt over the support during desiccation, thus resulting in its superior activity in benzene hydrogenation.展开更多
The deactivation of Ni/SiO2-Al2 O3 catalyst in hydrogenation of crude 1,4-butanediol was investigated.During the operation time of 2140 h,the catalyst showed slow activity decay.Characterization results,for four spent...The deactivation of Ni/SiO2-Al2 O3 catalyst in hydrogenation of crude 1,4-butanediol was investigated.During the operation time of 2140 h,the catalyst showed slow activity decay.Characterization results,for four spent catalysts used at different time,indicated that the main reason of the catalyst deactivation was the deposition of carbonaceous species that covered the active Ni and blocked mesopores of the catalyst.The TPO and SEM measurements revealed that the carbonaceous species included both oligomeric and polymeric species with high C/H ratio and showed sheet.Such carbonaceous species might be eliminated through either direct H2 reduction or the combined oxidation-reduction methodologies.展开更多
Methanol synthesis from hydrogenation of CO2 is investigated over Cu/ZnO/Al2O3 catalysts prepared by decomposition of M(Cu,Zn)-ammonia complexes (DMAC) at various temperatures.The catalysts were characterized in d...Methanol synthesis from hydrogenation of CO2 is investigated over Cu/ZnO/Al2O3 catalysts prepared by decomposition of M(Cu,Zn)-ammonia complexes (DMAC) at various temperatures.The catalysts were characterized in detail,including X-ray diffraction,N2 adsorption-desorption,N2O chemisorption,temperature-programmed reduction and evolved gas analyses.The influences of DMAC temperature,reaction temperature and specific Cu surface area on catalytic performance are investigated.It is considered that the aurichalcite phase in the precursor plays a key role in improving the physiochemical properties and activities of the final catalysts.The catalyst from rich-aurichalcite precursor exhibits large specific Cu surface area and high space time yield of methanol (212 g/(Lcat·h);T=513 K,p=3MPa,SV=12000 h-1).展开更多
Nickel-alumina catalysts supported on cordierite monoliths of honeycomb structure surpass essentially the conventional granulated ones with respect to the output in carbon dioxide reforming of methane. Adjusting the s...Nickel-alumina catalysts supported on cordierite monoliths of honeycomb structure surpass essentially the conventional granulated ones with respect to the output in carbon dioxide reforming of methane. Adjusting the surface acid-base properties of catalysts by introduction of alkali metal (Na, K) oxides inhibits the carbonization and as a result, improves the operational stability of these catalysts. An effect of promotion of nickel-alumina based composite doped by lanthanum oxide is found. This effect, caused by an additional route for the CO2 activation on Ni-La2O3/Al2O3/cordierite catalyst, is displayed in increase of methane conversion under conditions of an oxidant excess.展开更多
Methane decomposition reaction has been studied at three different activation temperatures(500°C,800°C and950°C)over mesoporous alumina supported Ni–Fe and Mn–Fe based bimetallic catalysts.On co-impre...Methane decomposition reaction has been studied at three different activation temperatures(500°C,800°C and950°C)over mesoporous alumina supported Ni–Fe and Mn–Fe based bimetallic catalysts.On co-impregnation of Ni on Fe/Al_2O_3the activity of the catalyst was retained even at the high activation temperature at 950°C and up to180 min.The Ni promotion enhanced the reducibility of Fe/Al_2O_3oxides showing higher catalytic activity with a hydrogen yield of 69%.The reactivity of bimetallic Mn and Fe over Al_2O_3catalyst decreased at 800°C and 950°C activation temperatures.Regeneration studies revealed that the catalyst could be effectively recycled up to 9times.The addition of O_2(1 ml,2 ml,4 ml)in the feed enhanced substantially CH_4conversion,the yield of hydrogen and the stability of the catalyst.展开更多
Ni/α-Al2O3 catalysts were found to be active in the temperature range 600 ~ 900℃ for both CO2 reforming and partial oxidation of methane.The effects of Ni loading,reaction temperature and feed gas ratio for the com...Ni/α-Al2O3 catalysts were found to be active in the temperature range 600 ~ 900℃ for both CO2 reforming and partial oxidation of methane.The effects of Ni loading,reaction temperature and feed gas ratio for the combination of CO2 reforming and partial oxidation of CH4 over Ni/α-Al2O3 were investigated.Catalysts of xwt%Ni/α-Al2O3(x=2.5,5,8 and 12) were prepared by wet impregnating the calcined support with a solution of nickel nitrate.XRD patterns and activity tests have verified that the 5wt%Ni/α-Al2O3 was the most active catalyst,as compared with the other prepared catalyst samples.An increase of the Ni loading to more than 5wt% led to a reduction in the Ni dispersion.In addition,by combining the endothermic carbon dioxide reforming reaction with the exothermic partial oxidation reaction,the loss of catalyst activity with time on stream was reduced with the amount of oxygen added to the feed.展开更多
Ni/Al_2O_3-SiO_2 catalysts were synthesized via one-step method employing SiO_2 as an additive for the selective hydrogenation of butyne-1,4-diol(B_3D) to butane-1,4-diol(B1D). The prepared catalysts were evaluated by...Ni/Al_2O_3-SiO_2 catalysts were synthesized via one-step method employing SiO_2 as an additive for the selective hydrogenation of butyne-1,4-diol(B_3D) to butane-1,4-diol(B1D). The prepared catalysts were evaluated by a series of characterization techniques including BET, XRD, SEM, EDX-mapping, TEM, H_2-TPR, XPS, NH_3-TPD and Py-FTIR. Compared to Ni/Al_2O_3 catalyst, the SiO_2-doped samples exhibited better B_3D conversion. SiO_2 could help to form a strong interaction between NiO with the support, which inhibited Ni agglomeration at high temperature, improved the Ni dispersion, and enhanced the hydrogenation activity. B_1D selectivity was mainly influenced by the quantity of Lewis acid sites in addition to the Ni dispersion. The catalyst with a silica loading of 6.4% demonstrated an excellent selectivity of 75.18%(by 13% higher than the contrastive Ni/Al_2O_3 catalyst), which was attributed to the larger amount of Lewis acid sites and the moderate interaction between NiO with the support, which could facilitate the nickel dispersion on a preferable surface area of 176.3 m^2/g of support.展开更多
高性能复合镀层具有优良的耐磨、耐蚀性能,能满足工业生产对材料性能的要求。研究了脉冲电沉积RE Ni W B PTFE Al2O3 复合镀层的成分、形貌及性能。结果表明:脉冲电流及Al2O3 固体颗粒能明显提高RE Ni W B PTFE Al2O3 复合镀层中W和B的...高性能复合镀层具有优良的耐磨、耐蚀性能,能满足工业生产对材料性能的要求。研究了脉冲电沉积RE Ni W B PTFE Al2O3 复合镀层的成分、形貌及性能。结果表明:脉冲电流及Al2O3 固体颗粒能明显提高RE Ni W B PTFE Al2O3 复合镀层中W和B的含量;与直流电沉积相比,脉冲电沉积RE Ni W B复合镀层的表面裂纹已明显减小,但裂纹仍存在,当Al2O3 耐磨颗粒及PTFE减摩微粒嵌入RE Ni W B复合镀层中以后,在SEM 400倍下观察,RE Ni W B PTFE Al2O3镀层已不存在裂纹, 而且镀液中Al2O3 颗粒含量越多,晶粒就越细;此外,研究表明,镀液中Al2O3 颗粒含量增加, RE Ni W B PTFE Al2O3 复合镀层镀态硬度增加,磨损率降低。展开更多
The crystal size distribution(CSD)was determined with small angle X-ray scattering technique.Theanticoking property of Ni-catalysts was investigated with the steam reforming of n-heptane in a TG-monitoredflow reacto...The crystal size distribution(CSD)was determined with small angle X-ray scattering technique.Theanticoking property of Ni-catalysts was investigated with the steam reforming of n-heptane in a TG-monitoredflow reactor.The results of this study show that the rate of coking on the supported Ni-catalysts depends main-ly on the percentage content of the large size fraction(25-70nm)of Ni-crystallites,and that the dispersion ofNi-crystallites and the anticoking property of the Ni/α-Al<sub>2</sub>O<sub>3</sub> catalysts were promoted obviously by theLa<sub>2</sub>O<sub>3</sub>-modification method.The variation of the Ni-CSD and the anticoking property of the catalysts were fur-ther tested through different periods of hydrothermal treatment.It is found that the content of the largeNi-crystal size fraction and the coking rate pass correspondingly through a maximum.展开更多
Supported nickel-based catalysts were prepared by the incipient wetness impregnation method for the selective hydrogenation of methyl isobutyl ketone to methyl isobutyl carbinol in a fixed-bed reactor. The effects of ...Supported nickel-based catalysts were prepared by the incipient wetness impregnation method for the selective hydrogenation of methyl isobutyl ketone to methyl isobutyl carbinol in a fixed-bed reactor. The effects of the nickel source,Ni loading, calcination time, and calcination temperature on the hydrogenation performance were studied. The experimental results showed that the Ni/γ-Al_2O_3 catalyst demonstrated the highest catalytic performance under the preparation conditions by using nickel nitrate as the nickel source with a NiO loading of 20%, followed by calcination at 440°C for 5h. In addition,this catalyst showed the largest specific surface area, best crystal structure, highest active component content, smallest particle size, and uniform distribution of NiO on the surface of the carrier. The nickel-based catalyst prepared using the optimized conditions exhibited a 96.1% conversion of methyl isobutyl ketone, with a methyl isobutyl carbinol selectivity of 99.6%. The described procedure is very effective for the preparation of methyl isobutyl carbinol using methyl isobutyl ketone as the feedstock.展开更多
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
Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried ...Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried out over coral reef-like Ni/Al2O3 catalysts in a continuous flow type fixed-bed reactor.The structure and properties of the fresh and used catalysts were studied by SEM,N2 adsorption-desorption,XRD,H2-TPR,O2-TPO,TG and ICP-AES techniques.The results showed that the coral reef-like Ni/Al2O3 catalysts exhibited better activity than the conventional Ni/Al2O3-H2O catalysts.The activities of coral reef-like catalysts were in the order of Ni/Al2O3-673Ni/Al2O3-573Ni/Al2O3- 473Ni/Al2O3-773.Ni/Al2O3-673-EG catalyst showed not only good activity and improved stability but also superior resistance to carbon deposition,sintering,and Ni loss.Under the reaction conditions of CO/H2(molar ratio)=1:3,593 K,atmospheric pressure and a GHSV of 2500 h-1,CH4 selectivity was 84.7%,and the CO conversion reached 98.2%.展开更多
Deactivation mechanism of Cr-Al2O3catalyst and the interaction of Cr-A1 in the dehydrogenation of isobutane, as well as the nature of the catalytic active center, were studied using XRD, SEM, XPS, H2-TPR, isobutane-TP...Deactivation mechanism of Cr-Al2O3catalyst and the interaction of Cr-A1 in the dehydrogenation of isobutane, as well as the nature of the catalytic active center, were studied using XRD, SEM, XPS, H2-TPR, isobutane-TPR and TPO techniques. The results revealed that the deactivation of Cr-Al2O3 catalyst was mainly caused by carbon deposition on its surface. The Cr3+ ion could not be reduced by hydrogen but could be reduced to Cr2+ by hydrocarbons and monoxide carbon. The active center for isobutane dehydrogenation could be Cr2+/Cr3+ produced from Cr6+ by the on line reduction of hydrocarbon and carbon monoxide. The binding energy of Al3+ was strongly affected by the state of chromium cations in the catalysts.展开更多
Ni-based catalysts doped with copper additives were studied on their role in ethanol steam reforming reaction. The effects of Cu content, support species involving Al2O3-SIO2, Al2O3-MgO, Al2O3-ZnO, and Al2O3-La2O3, on...Ni-based catalysts doped with copper additives were studied on their role in ethanol steam reforming reaction. The effects of Cu content, support species involving Al2O3-SIO2, Al2O3-MgO, Al2O3-ZnO, and Al2O3-La2O3, on the catalytic performance were studied. Characterizations by TPR, XRD, NH3-TPD, XPS, and TGA indicated that catalysts 30Ni5Cu/Al2O3-MgO and 30Ni5Cu/Al2O3-ZnO have much higher H2 selectivity than 30Ni5Cu/Al2O3-SiO2, as well as good coke resistance. H2 selectivity for 30Ni5Cu/Al2O3-MgO catalyst was 73.3% at 450 ℃ and increased to 94.0% at 600℃, whereas for 30Ni5Cu/Al2O3-ZnO catalyst, the H2 selectivity was 63.6% at 450 ℃ and 95.2% at 600℃. TheseAl2O3-MgO and Al2O3-ZnO supported Ni-Cu bimetallic catalysts may have important applications in the production of hydrogen by ethanol steam reforming reactions.展开更多
A series of iron-based Fischer-Tropsch synthesis (FTS) catalysts incorporated with Al2O3 binder were prepared by the combination of co-precipitation and spray drying technology. The catalyst samples were characteriz...A series of iron-based Fischer-Tropsch synthesis (FTS) catalysts incorporated with Al2O3 binder were prepared by the combination of co-precipitation and spray drying technology. The catalyst samples were characterized by using N2 physical adsorption, temperature-programmed reduction/desorption (TPR/TPD) and MSssbauer effect spectroscopy (MES) methods. The characterization results indicated that the BET surface area increases with increasing Al2O3 content and passes through a maximum at the Al2O3/Fe ratio of 10/100 (weight basis). After the point, it decreases with further increase in Al2O3 content. The incorporation of Al2O3 binder was found to weaken the surface basicity and suppress the reduction and carburization of iron-based catalysts probably due to the strong K-Al2O3 and Fe-Al2O3 interactions. Furthermore, the H2 adsorption ability of the catalysts is enhanced with increasing Al2O3 content. The FTS performances of the catalysts were tested in a slurry-phase continuously stirred tank reactor (CSTR) under the reaction conditions of 260 ℃, 1.5 MPa, 1000 h^-1 and molar ratio of H2/CO 0.67 for 200 h. The results showed that the addition of small amounts of Al2O3 affects the activity of iron-based catalysts to a little extent. However, with further increase of Al2O3 content, the FTS activity and water gas shift reaction (WGS) activity are decreased severely. The addition of appropriate Al2O3 do not affect the product selectivity, but the catalysts incorporated with large amounts of Al2O3 have higher selectivity for light hydrocarbons and lower selectivity for heavy hydrocarbons.展开更多
Characteristics of carbon deposition of CH 4 and C 2H 4 decomposition over supported Ni and Ni Ce catalysts were studied by using a pulse reaction as well as BET, TPR, XPS and hydrogen chemisorption techniques. It...Characteristics of carbon deposition of CH 4 and C 2H 4 decomposition over supported Ni and Ni Ce catalysts were studied by using a pulse reaction as well as BET, TPR, XPS and hydrogen chemisorption techniques. It is found that there is a metal semiconductor interaction (MScI) in the Ni Ce catalyst, and the effect of MScI on the carbon deposition of CH 4 decomposition is opposite to that of C 2H 4. A novel model of carbon deposition of CH 4 or C 2H 4 decomposition was proposed.展开更多
The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated.A series of Al2O3 catalysts containing different active metals(Co,Mo,Ni,W)were prepared by incipient wetness ...The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated.A series of Al2O3 catalysts containing different active metals(Co,Mo,Ni,W)were prepared by incipient wetness impregnation.The effects of different active metals forms(oxidation,reduction,sulfuration)and reaction conditions on naphthalene hydrogenation were investigated and the catalysts were characterized by XRD,XPS,BET,NH3-TPD and SEM.Especially,Ni-Mo/Al2O3 was first used in this reactive system.The results show that the oxidative4%Ni O-20%MoO3/Al2O3 is the best catalyst for the preparation of tetralin.The conversion of naphthalene and the selectivity of tetralin can reach 95.62%and 99.75%respectively at 200℃,8 h and 6 MPa.Compared with reduced and sulfureted 4%Ni O-20%MoO3/Al2O3 catalysts,oxidative 4%Ni O-20%MoO3/Al2O3 has a well dispersed and uniform monolayer of the active metals,larger pore volume and size,and larger total acidity.NiO-MoO3/Al2O3 has a synergistic effect between NiO activity and MoO3 selectivity.展开更多
In this work, a series of coal-based active carbon (CAC) catalysts loaded by A1203 were prepared by sol-gel method and used for the simulta- neous catalytic hydrolysis of carbonyl sulfide (COS) and carbon disulfi...In this work, a series of coal-based active carbon (CAC) catalysts loaded by A1203 were prepared by sol-gel method and used for the simulta- neous catalytic hydrolysis of carbonyl sulfide (COS) and carbon disulfide (CS2) at relatively low temperatures of 30-70 ℃. The influences of calcinations temperatures and operation conditions such as: reaction temperature, 02 concentration, gas hourly space velocity (GHSV) and relative humidity (RH) were also discussed respectively. The results showed that catalysts with 5.0 wt% A1203 calcined at 300 ℃ had supe- rior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50 ℃, catalytic hydrolysis activity of COS could be enhanced but that of CS2 was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2 decrease. A small amount of 02 introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2.展开更多
An alloy steel/alumina composite was successfully fabricated by pressureless infiltration of X10CrNi18-8 steel melt on 30%(mass fraction) Ni-containing alumina based composite ceramic(Ni/Al2O3) at 1 600 ℃.The infiltr...An alloy steel/alumina composite was successfully fabricated by pressureless infiltration of X10CrNi18-8 steel melt on 30%(mass fraction) Ni-containing alumina based composite ceramic(Ni/Al2O3) at 1 600 ℃.The infiltration quality and interfacial bonding behavior were investigated by SEM,EDS,XRD and tensile tests.The results show that there is an obvious interfacial reaction layer between the alloying steel and the Ni/Al2O3 composite ceramic.The interfacial reactive products are(FexAly)3O4 intermetallic phase and(AlxCry)2O3 solid solution.The interfacial bonding strength is as high as about 67.5 MPa.The bonding mechanism of X10CrNi18-8 steel with the composite ceramic is that Ni inside the ceramic bodies dissolves into the alloy melt and transforms into liquid channels,consequently inducing the steel melt infiltrating and filling in the pores and the liquid channels.Moreover,the metallurgical bonding and interfacial reactive bonding also play a key role on the stability of the bonding interface.展开更多
文摘Amorphous Ni B/γ Al 2O 3 catalyst 1 is prepared with chemical reduction by KBH 4 solution after wetness impregnation and desiccation at 70 ℃ first and then at 110 ℃ for thorough water removal. Its higher catalytic activity than amorphous Ni B/γ Al 2O 3 catalyst 2, prepared by conventional one step desiccation procedure at 110 ℃, is identified in liquid phase benzene hydrogenation to cyclohexane. Both catalysts are characterized by XRD and SEM, Ni B/γ Al 2O 3 catalyst 1 has a higher active specific surface area and dispersion degree, which can be assigned to more effective distribution of nickel salt over the support during desiccation, thus resulting in its superior activity in benzene hydrogenation.
基金Supported by the National Natural Science Foundation of China(21673132).
文摘The deactivation of Ni/SiO2-Al2 O3 catalyst in hydrogenation of crude 1,4-butanediol was investigated.During the operation time of 2140 h,the catalyst showed slow activity decay.Characterization results,for four spent catalysts used at different time,indicated that the main reason of the catalyst deactivation was the deposition of carbonaceous species that covered the active Ni and blocked mesopores of the catalyst.The TPO and SEM measurements revealed that the carbonaceous species included both oligomeric and polymeric species with high C/H ratio and showed sheet.Such carbonaceous species might be eliminated through either direct H2 reduction or the combined oxidation-reduction methodologies.
基金supported by the National Basic Research Program of China (No. 2011CB201404)the financial support of the State Key Laboratory for Oxo Synthesis and Selective Oxidation (OSSO) of China
文摘Methanol synthesis from hydrogenation of CO2 is investigated over Cu/ZnO/Al2O3 catalysts prepared by decomposition of M(Cu,Zn)-ammonia complexes (DMAC) at various temperatures.The catalysts were characterized in detail,including X-ray diffraction,N2 adsorption-desorption,N2O chemisorption,temperature-programmed reduction and evolved gas analyses.The influences of DMAC temperature,reaction temperature and specific Cu surface area on catalytic performance are investigated.It is considered that the aurichalcite phase in the precursor plays a key role in improving the physiochemical properties and activities of the final catalysts.The catalyst from rich-aurichalcite precursor exhibits large specific Cu surface area and high space time yield of methanol (212 g/(Lcat·h);T=513 K,p=3MPa,SV=12000 h-1).
文摘Nickel-alumina catalysts supported on cordierite monoliths of honeycomb structure surpass essentially the conventional granulated ones with respect to the output in carbon dioxide reforming of methane. Adjusting the surface acid-base properties of catalysts by introduction of alkali metal (Na, K) oxides inhibits the carbonization and as a result, improves the operational stability of these catalysts. An effect of promotion of nickel-alumina based composite doped by lanthanum oxide is found. This effect, caused by an additional route for the CO2 activation on Ni-La2O3/Al2O3/cordierite catalyst, is displayed in increase of methane conversion under conditions of an oxidant excess.
基金the Deanship of Scientific Research at King Saud University for its funding this research group No.(RG-1436-119)
文摘Methane decomposition reaction has been studied at three different activation temperatures(500°C,800°C and950°C)over mesoporous alumina supported Ni–Fe and Mn–Fe based bimetallic catalysts.On co-impregnation of Ni on Fe/Al_2O_3the activity of the catalyst was retained even at the high activation temperature at 950°C and up to180 min.The Ni promotion enhanced the reducibility of Fe/Al_2O_3oxides showing higher catalytic activity with a hydrogen yield of 69%.The reactivity of bimetallic Mn and Fe over Al_2O_3catalyst decreased at 800°C and 950°C activation temperatures.Regeneration studies revealed that the catalyst could be effectively recycled up to 9times.The addition of O_2(1 ml,2 ml,4 ml)in the feed enhanced substantially CH_4conversion,the yield of hydrogen and the stability of the catalyst.
文摘Ni/α-Al2O3 catalysts were found to be active in the temperature range 600 ~ 900℃ for both CO2 reforming and partial oxidation of methane.The effects of Ni loading,reaction temperature and feed gas ratio for the combination of CO2 reforming and partial oxidation of CH4 over Ni/α-Al2O3 were investigated.Catalysts of xwt%Ni/α-Al2O3(x=2.5,5,8 and 12) were prepared by wet impregnating the calcined support with a solution of nickel nitrate.XRD patterns and activity tests have verified that the 5wt%Ni/α-Al2O3 was the most active catalyst,as compared with the other prepared catalyst samples.An increase of the Ni loading to more than 5wt% led to a reduction in the Ni dispersion.In addition,by combining the endothermic carbon dioxide reforming reaction with the exothermic partial oxidation reaction,the loss of catalyst activity with time on stream was reduced with the amount of oxygen added to the feed.
基金Financial support from the National Natural Science Foundation of China (21163019) is gratefully acknowledged
文摘Ni/Al_2O_3-SiO_2 catalysts were synthesized via one-step method employing SiO_2 as an additive for the selective hydrogenation of butyne-1,4-diol(B_3D) to butane-1,4-diol(B1D). The prepared catalysts were evaluated by a series of characterization techniques including BET, XRD, SEM, EDX-mapping, TEM, H_2-TPR, XPS, NH_3-TPD and Py-FTIR. Compared to Ni/Al_2O_3 catalyst, the SiO_2-doped samples exhibited better B_3D conversion. SiO_2 could help to form a strong interaction between NiO with the support, which inhibited Ni agglomeration at high temperature, improved the Ni dispersion, and enhanced the hydrogenation activity. B_1D selectivity was mainly influenced by the quantity of Lewis acid sites in addition to the Ni dispersion. The catalyst with a silica loading of 6.4% demonstrated an excellent selectivity of 75.18%(by 13% higher than the contrastive Ni/Al_2O_3 catalyst), which was attributed to the larger amount of Lewis acid sites and the moderate interaction between NiO with the support, which could facilitate the nickel dispersion on a preferable surface area of 176.3 m^2/g of support.
文摘高性能复合镀层具有优良的耐磨、耐蚀性能,能满足工业生产对材料性能的要求。研究了脉冲电沉积RE Ni W B PTFE Al2O3 复合镀层的成分、形貌及性能。结果表明:脉冲电流及Al2O3 固体颗粒能明显提高RE Ni W B PTFE Al2O3 复合镀层中W和B的含量;与直流电沉积相比,脉冲电沉积RE Ni W B复合镀层的表面裂纹已明显减小,但裂纹仍存在,当Al2O3 耐磨颗粒及PTFE减摩微粒嵌入RE Ni W B复合镀层中以后,在SEM 400倍下观察,RE Ni W B PTFE Al2O3镀层已不存在裂纹, 而且镀液中Al2O3 颗粒含量越多,晶粒就越细;此外,研究表明,镀液中Al2O3 颗粒含量增加, RE Ni W B PTFE Al2O3 复合镀层镀态硬度增加,磨损率降低。
文摘The crystal size distribution(CSD)was determined with small angle X-ray scattering technique.Theanticoking property of Ni-catalysts was investigated with the steam reforming of n-heptane in a TG-monitoredflow reactor.The results of this study show that the rate of coking on the supported Ni-catalysts depends main-ly on the percentage content of the large size fraction(25-70nm)of Ni-crystallites,and that the dispersion ofNi-crystallites and the anticoking property of the Ni/α-Al<sub>2</sub>O<sub>3</sub> catalysts were promoted obviously by theLa<sub>2</sub>O<sub>3</sub>-modification method.The variation of the Ni-CSD and the anticoking property of the catalysts were fur-ther tested through different periods of hydrothermal treatment.It is found that the content of the largeNi-crystal size fraction and the coking rate pass correspondingly through a maximum.
基金financially supported by the National Natural Science Foundation of China (91634101)the Project on Construction of Innovative Teams and Teacher Career Development for Universities and Colleges under Beijing Municipality (IDHT20180508)
文摘Supported nickel-based catalysts were prepared by the incipient wetness impregnation method for the selective hydrogenation of methyl isobutyl ketone to methyl isobutyl carbinol in a fixed-bed reactor. The effects of the nickel source,Ni loading, calcination time, and calcination temperature on the hydrogenation performance were studied. The experimental results showed that the Ni/γ-Al_2O_3 catalyst demonstrated the highest catalytic performance under the preparation conditions by using nickel nitrate as the nickel source with a NiO loading of 20%, followed by calcination at 440°C for 5h. In addition,this catalyst showed the largest specific surface area, best crystal structure, highest active component content, smallest particle size, and uniform distribution of NiO on the surface of the carrier. The nickel-based catalyst prepared using the optimized conditions exhibited a 96.1% conversion of methyl isobutyl ketone, with a methyl isobutyl carbinol selectivity of 99.6%. The described procedure is very effective for the preparation of methyl isobutyl carbinol using methyl isobutyl ketone as the feedstock.
文摘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.
基金financially supported by Independent Research Subject from Ministry of Science and Technology of China(No.2008BWZ005)
文摘Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried out over coral reef-like Ni/Al2O3 catalysts in a continuous flow type fixed-bed reactor.The structure and properties of the fresh and used catalysts were studied by SEM,N2 adsorption-desorption,XRD,H2-TPR,O2-TPO,TG and ICP-AES techniques.The results showed that the coral reef-like Ni/Al2O3 catalysts exhibited better activity than the conventional Ni/Al2O3-H2O catalysts.The activities of coral reef-like catalysts were in the order of Ni/Al2O3-673Ni/Al2O3-573Ni/Al2O3- 473Ni/Al2O3-773.Ni/Al2O3-673-EG catalyst showed not only good activity and improved stability but also superior resistance to carbon deposition,sintering,and Ni loss.Under the reaction conditions of CO/H2(molar ratio)=1:3,593 K,atmospheric pressure and a GHSV of 2500 h-1,CH4 selectivity was 84.7%,and the CO conversion reached 98.2%.
基金supported by the Natural Science Foundation of Shandong Provence of China(ZR2013BM008)
文摘Deactivation mechanism of Cr-Al2O3catalyst and the interaction of Cr-A1 in the dehydrogenation of isobutane, as well as the nature of the catalytic active center, were studied using XRD, SEM, XPS, H2-TPR, isobutane-TPR and TPO techniques. The results revealed that the deactivation of Cr-Al2O3 catalyst was mainly caused by carbon deposition on its surface. The Cr3+ ion could not be reduced by hydrogen but could be reduced to Cr2+ by hydrocarbons and monoxide carbon. The active center for isobutane dehydrogenation could be Cr2+/Cr3+ produced from Cr6+ by the on line reduction of hydrocarbon and carbon monoxide. The binding energy of Al3+ was strongly affected by the state of chromium cations in the catalysts.
基金973 Program (2006CB202500)the National Natural Science Foundation of China (20676096)New Century Excellent Talents in University.9gram (2006CB202500)
文摘Ni-based catalysts doped with copper additives were studied on their role in ethanol steam reforming reaction. The effects of Cu content, support species involving Al2O3-SIO2, Al2O3-MgO, Al2O3-ZnO, and Al2O3-La2O3, on the catalytic performance were studied. Characterizations by TPR, XRD, NH3-TPD, XPS, and TGA indicated that catalysts 30Ni5Cu/Al2O3-MgO and 30Ni5Cu/Al2O3-ZnO have much higher H2 selectivity than 30Ni5Cu/Al2O3-SiO2, as well as good coke resistance. H2 selectivity for 30Ni5Cu/Al2O3-MgO catalyst was 73.3% at 450 ℃ and increased to 94.0% at 600℃, whereas for 30Ni5Cu/Al2O3-ZnO catalyst, the H2 selectivity was 63.6% at 450 ℃ and 95.2% at 600℃. TheseAl2O3-MgO and Al2O3-ZnO supported Ni-Cu bimetallic catalysts may have important applications in the production of hydrogen by ethanol steam reforming reactions.
基金The financial support from the National Natural Science Foundation of China (20590361)the National Outstanding Young Scientists Foundation of China (20625620)
文摘A series of iron-based Fischer-Tropsch synthesis (FTS) catalysts incorporated with Al2O3 binder were prepared by the combination of co-precipitation and spray drying technology. The catalyst samples were characterized by using N2 physical adsorption, temperature-programmed reduction/desorption (TPR/TPD) and MSssbauer effect spectroscopy (MES) methods. The characterization results indicated that the BET surface area increases with increasing Al2O3 content and passes through a maximum at the Al2O3/Fe ratio of 10/100 (weight basis). After the point, it decreases with further increase in Al2O3 content. The incorporation of Al2O3 binder was found to weaken the surface basicity and suppress the reduction and carburization of iron-based catalysts probably due to the strong K-Al2O3 and Fe-Al2O3 interactions. Furthermore, the H2 adsorption ability of the catalysts is enhanced with increasing Al2O3 content. The FTS performances of the catalysts were tested in a slurry-phase continuously stirred tank reactor (CSTR) under the reaction conditions of 260 ℃, 1.5 MPa, 1000 h^-1 and molar ratio of H2/CO 0.67 for 200 h. The results showed that the addition of small amounts of Al2O3 affects the activity of iron-based catalysts to a little extent. However, with further increase of Al2O3 content, the FTS activity and water gas shift reaction (WGS) activity are decreased severely. The addition of appropriate Al2O3 do not affect the product selectivity, but the catalysts incorporated with large amounts of Al2O3 have higher selectivity for light hydrocarbons and lower selectivity for heavy hydrocarbons.
文摘Characteristics of carbon deposition of CH 4 and C 2H 4 decomposition over supported Ni and Ni Ce catalysts were studied by using a pulse reaction as well as BET, TPR, XPS and hydrogen chemisorption techniques. It is found that there is a metal semiconductor interaction (MScI) in the Ni Ce catalyst, and the effect of MScI on the carbon deposition of CH 4 decomposition is opposite to that of C 2H 4. A novel model of carbon deposition of CH 4 or C 2H 4 decomposition was proposed.
基金supported by the Joint Funds of National Key R&D Program of China(2018YFB0604603)the National Natural Science Foundation of China(21536009,21776229)+2 种基金Science and Technology Plan Projects of Shaanxi Province(2017ZDCXL-GY-10-03,2018ZDXMGY-167)The Young Science and Technology Star Project of Shaanxi Province(2017KJXX-62)Science and Technology Program of Yulin(2018-2-22)。
文摘The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated.A series of Al2O3 catalysts containing different active metals(Co,Mo,Ni,W)were prepared by incipient wetness impregnation.The effects of different active metals forms(oxidation,reduction,sulfuration)and reaction conditions on naphthalene hydrogenation were investigated and the catalysts were characterized by XRD,XPS,BET,NH3-TPD and SEM.Especially,Ni-Mo/Al2O3 was first used in this reactive system.The results show that the oxidative4%Ni O-20%MoO3/Al2O3 is the best catalyst for the preparation of tetralin.The conversion of naphthalene and the selectivity of tetralin can reach 95.62%and 99.75%respectively at 200℃,8 h and 6 MPa.Compared with reduced and sulfureted 4%Ni O-20%MoO3/Al2O3 catalysts,oxidative 4%Ni O-20%MoO3/Al2O3 has a well dispersed and uniform monolayer of the active metals,larger pore volume and size,and larger total acidity.NiO-MoO3/Al2O3 has a synergistic effect between NiO activity and MoO3 selectivity.
基金supported by the Ministry of Environmental Protection,Public Welfare Project(Contract No 201109034)the National Natural Science Foundation(U1137603)
文摘In this work, a series of coal-based active carbon (CAC) catalysts loaded by A1203 were prepared by sol-gel method and used for the simulta- neous catalytic hydrolysis of carbonyl sulfide (COS) and carbon disulfide (CS2) at relatively low temperatures of 30-70 ℃. The influences of calcinations temperatures and operation conditions such as: reaction temperature, 02 concentration, gas hourly space velocity (GHSV) and relative humidity (RH) were also discussed respectively. The results showed that catalysts with 5.0 wt% A1203 calcined at 300 ℃ had supe- rior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50 ℃, catalytic hydrolysis activity of COS could be enhanced but that of CS2 was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2 decrease. A small amount of 02 introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2.
基金Project(2009ZM0296) supported by the Fundamental Research Funds for the Central Universities in China
文摘An alloy steel/alumina composite was successfully fabricated by pressureless infiltration of X10CrNi18-8 steel melt on 30%(mass fraction) Ni-containing alumina based composite ceramic(Ni/Al2O3) at 1 600 ℃.The infiltration quality and interfacial bonding behavior were investigated by SEM,EDS,XRD and tensile tests.The results show that there is an obvious interfacial reaction layer between the alloying steel and the Ni/Al2O3 composite ceramic.The interfacial reactive products are(FexAly)3O4 intermetallic phase and(AlxCry)2O3 solid solution.The interfacial bonding strength is as high as about 67.5 MPa.The bonding mechanism of X10CrNi18-8 steel with the composite ceramic is that Ni inside the ceramic bodies dissolves into the alloy melt and transforms into liquid channels,consequently inducing the steel melt infiltrating and filling in the pores and the liquid channels.Moreover,the metallurgical bonding and interfacial reactive bonding also play a key role on the stability of the bonding interface.