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1.
采用溶胶凝胶法制备了La0.6Sr0.4NixCo1-xO3钙钛矿催化剂,并测试了该催化剂在焦炉煤气CO2重整反应中的性能.通过X射线衍射、N2吸附脱附、程序升温还原、扫描电镜、透射电镜和热重-微分扫描量热等方法对催化剂进行了表征.结果表明,溶胶凝胶法合成的La0.6Sr0.4NixCo1-xO3催化剂形成了钙钛矿结构的固溶体.着重考察了钙钛矿催化剂焙烧温度和A位Ni的掺杂含量对其催化性能和反应后积碳的影响.结果表明: La0.6Sr0.4NixCo1-xO3钙钛矿催化剂在反应中生成了活性金属Ni, Co颗粒和La2O2CO3,这些组分对催化剂的活性和稳定性起关键性的作用,并且能够抑制积碳的形成;焦炉煤气中的富氢气体具有抑制甲烷裂解反应发生的作用,从而减少催化剂的积碳.  相似文献   

2.
采用溶胶凝胶法制备了La0.6Sr0.4NixCo1-xO3钙钛矿催化剂,并测试了该催化剂在焦炉煤气CO2重整反应中的性能.通过X射线衍射、N2吸附脱附、程序升温还原、扫描电镜、透射电镜和热重-微分扫描量热等方法对催化剂进行了表征.结果表明,溶胶凝胶法合成的La0.6Sr0.4NixCo1-xO3催化剂形成了钙钛矿结构的固溶体.着重考察了钙钛矿催化剂焙烧温度和A位Ni的掺杂含量对其催化性能和反应后积碳的影响.结果表明:La0.6Sr0.4NixCo1-xO3钙钛矿催化剂在反应中生成了活性金属Ni,Co颗粒和La2O2CO3,这些组分对催化剂的活性和稳定性起关键性的作用,并且能够抑制积碳的形成;焦炉煤气中的富氢气体具有抑制甲烷裂解反应发生的作用,从而减少催化剂的积碳.  相似文献   

3.
制备方法对Pd催化剂上丙烯选择性还原NO反应性能的影响   总被引:8,自引:0,他引:8  
 采用三种不同方法制备了氧化铝负载的Pd催化剂.比表面积测定\r\n结果表明,与浸渍法相比,溶胶-凝胶加浸渍法和溶胶-凝胶法制备的\r\nPd/Al2O3样品具有较大的比表面积,但抗烧结性能不佳.其中采用溶\r\n胶-凝胶法制备的样品中,由于Pd分散于体相中,表面的活性位相对较\r\n少,造成催化剂在NO选择性还原反应中的活性较差;而将Pd浸渍于溶胶\r\n-凝胶法制得的Al2O3载体上所获得的催化剂比表面积较大,活性较好\r\n.添加CeO2的样品活性总体上比Pd/Al2O3样品高.其中采用溶胶-凝\r\n胶法制备的样品比表面积不大,并且XRD数据表明Al2O3和CeO2是高度分\r\n散并均匀地搀杂在一起的,不象在浸渍法制备的样品中那样以大晶粒的\r\n形式存在,因而CeO2的助剂作用没有充分体现出来,催化剂的活性比浸\r\n渍法制备的样品差一些.  相似文献   

4.
 采用溶胶-凝胶法、共沉淀法和冷冻干燥法,制备了LaxMnyPbz\r\nO复合型金属氧化物载体,并以PdCl2或Na2PdCl4的水溶液为浸渍液,通\r\n过浸渍方法制得固相催化剂,用于一步合成碳酸二苯酯.用XRD,TEM及\r\nSEM对载体及催化剂进行了表征.结果表明,三种载体的主要物相皆为\r\nLa0.3Mn0.5PbO,溶胶-凝胶法制得的载体及催化剂的粒径分布较好\r\n,空隙率较大,活性组分分散度较高;溶胶-凝胶法制得的催化剂的催\r\n化性能较好,碳酸二苯酯选择性可高于99.5%.  相似文献   

5.
采用共沉淀法和原位溶胶-凝胶法制备了TiO2-Al2O3复合载体,其负载的磷化镍催化剂采用等体积浸渍法和H2原位还原法制备.通过N2吸附(BET)、X射线衍射(XRD)、透射电镜(TEM)、程序升温还原(TPR),X射线光电子能谱(XPS)和等离子体发射光谱(ICP-AES)表征技术对催化剂进行了表征,并通过喹啉的加氢脱氮反应评价了催化剂的加氢脱氮性能.结果表明,原位溶胶-凝胶法制成的复合载体基本保留了原有的γ-Al2O3的孔特征,具有较大的比表面积和较宽的孔分布,TiO2主要以表面富集的形式分散在管状的γ-Al2O3表面,其负载的磷化镍催化剂还原后所形成的活性相为Ni2P和Ni12P5;而共沉淀法制成的复合载体比表面积较小,孔径分布更加集中,TiO2趋于在块状的Al2O3表面均匀分散,其负载的磷化镍催化剂具有更好的可还原性,还原后所形成的活性相为Ni2P.不同的载体制备方法和不同的钛铝比对催化剂加氢脱氮性能影响较大,当n(Ti)/n(Al)=1/8时,共沉淀法载体负载的催化剂表现出最佳的加氢脱氮性能,在340℃,3 MPa,氢油体积比500,液时空速3 h-1的反应条件下,喹啉的脱氮率可以达到91.3%.  相似文献   

6.
 用等体积浸渍法制备了ZrO2-SiO2(ZrSiO)表面复合氧化物负载的Cu-Ni催化剂,并用IR,TPR,TPD及微反技术考察了K2O助剂对CO2和CH3OH在Cu-Ni/ZrSiO催化剂表面上的吸附及合成碳酸二甲酯(DMC)反应性能的影响.结果表明:加入K2O助剂使CO2在催化剂表面上的吸附增强,当n(K)/n(Cu+Ni)=15%时,CO2在催化剂表面上吸附后生成K2CO3;CH3OH在催化剂表面上的解离吸附态(CH3O-和H+)的吸附减弱;CO2和CH3OH在Cu-Ni/ZrSiO催化剂表面上反应的主要产物为DMC,H2O,CO和CH2O;随着K2O助剂的加入,反应转化率及DMC选择性提高,副产物(CO和CH2O)的选择性下降.根据实验结果,探讨了K2O对催化剂表面活性中心电荷分布的影响.  相似文献   

7.
采用浸渍法、溶胶 凝胶过程与普通干燥、超临界干燥过程相结合的方法制备了三种 82 3K焙烧的NiO CeO2 Al2 O3 体系催化剂 ,分别为浸渍型催化剂 (iNCA5 5 0 )、干凝胶催化剂 (xNCA5 5 0 )和气凝胶催化剂 (aNCA5 5 0 ) ,考察了它们在CH4 CO2 重整反应中的催化性能及反应的稳定性 ,采用TG、TEM、XPS等手段研究了反应前后催化剂的结构性质。研究结果表明 ,在 10 73K、CH4 CO2 =1∶1、180 0 0mL h·g的反应条件下 ,三种催化剂中aNCA5 5 0在CH4 CO2 重整反应过程中的积碳量较大 ,但却具有最好的反应稳定性 ;aNCA5 5 0具有较大积碳量与其表面酸量较大、酸性较强及较大镍分散度有关 ,然而由于它具有较大的积碳容量和很强的金属抗烧结能力 ,因此保持了较好的反应稳定性。催化剂积碳和金属镍烧结导致催化剂表面活性中心数目减少是催化剂失活的主要原因。  相似文献   

8.
采用浸渍法和溶胶-凝胶法制备了三种含Mg,Fe和Al量相同的Fe2O3-MgO/γ-Al2O3,Fe2O3/MgAl2O4和MgFe0.1Al1.9O4催化剂,在580°C考察了它们催化乙苯与CO2氧化脱氢反应性能,并采用X射线衍射,表面元素分析,H2-程序升温还原和CO2-程序升温脱附等技术对催化剂体相及表面性质进行了表征.结果表明,催化剂制备方法影响Fe物种的存在形态,进而影响催化剂的稳定性和活性.采用浸渍法制备的Fe2O3/MgAl2O4催化剂含有高度分散的Fe2O3活性物种,该物种具有较好的初活性,但是稳定性较差;而采用溶胶-凝胶法制备的MgFe0.1Al1.9O4催化剂中,Fe物种主要以同晶取代的形式存在于尖晶石骨架中,因而具有较高的乙苯与CO2氧化脱氢催化活性和稳定性.  相似文献   

9.
Cu/WO3-NiO上光促表面催化二氧化碳与水合成甲醇反应的规律   总被引:12,自引:0,他引:12  
 采用溶胶-凝胶法制备了n-p复合半导体材料0.75%Cu/WO3-1.5%NiO,用X射线衍射、透射电镜、红外光谱、紫外-可见光漫反射和程序升温脱附等技术对材料结构、吸光性能和化学吸附性能进行了表征,研究了该材料对CO2与H2O合成CH3OH的光促表面催化反应(PSSR)规律.结果表明:所制备的材料明显有利于促进目的反应,室温条件下就有CH3OH生成,选择性超过90%,升高反应温度可提高CH3OH产量,且选择性仍高于88%.根据实验结果,得出CO2在材料表面的卧式吸附态为CH3OH的前驱物,并对PSSR机理进行了讨论.  相似文献   

10.
La2NiO4/Al2O3催化剂上CH4/CO2的重整   总被引:9,自引:1,他引:8  
 通过溶胶-凝胶方法制备了尖晶石结构的La2NiO4/Al2O3催化剂,采用BET,XRD和TG表征了催化剂的孔分布、比表面积、体相组成以及凝胶样品的热失重和热分解过程.将催化剂应用于CH4/CO2重整反应制合成气,考察了惰性气体和反应温度对转化率、选择性以及积碳的影响.结果表明,在高空速(GHSV=4.8×104ml/(g·h))下,CH4和CO2转化率分别为51%和60%,CO和H2的选择性约为98%和92%,惰性气体He的引入明显地提高了CH4和CO2的转化率.  相似文献   

11.
This paper provides a calculation method for carbon activity in CO-H2-H2O atmosphere. The thermodynamic parameters (aC) gas (carbon activity in environment) of different compositions at any temperature can be obtained by △Go T. A theoretical analysis has been conducted into the thermodynamic role of iron and the dependence of possible metal-dusting occurrence on temperature, gas composition and total pressure. In CO-H2-H2O gas mixtures, decreasing the molar fraction of H2O and increasing total pressure expands the temperature region for metal dusting. In CO-H2-H2O gas mixture of different compositions at any temperature and pressure for Fe, depending on relative values of (aC) gas , (aC) Fe3C/Fe and aC = 1, three zones were found to exist.  相似文献   

12.
This paper provides a calculation method for carbon activity in CO-H2-H2O atmosphere. The thermodynamic parameters (αC>)gas (carbon activity in environment) of different compositions at any temperature can be obtained by ΔGoT. A theoretical analysis has been conducted into the thermodynamic role of iron and the dependence of possible metal-dusting occurrence on temperature, gas composition and total pressure. In CO-H2-H2O gas mixtures, decreasing the molar fraction of H2O and increasing total pressure expands the temperature region for metal dusting. In CO-H2-H2O gas mixture of different compositions at any temperature and pressure for Fe, depending on relative values of (αC)gas, (αC)Fe3C/Fe and αC=1, three zones were found to exist.  相似文献   

13.
《Mendeleev Communications》2022,32(3):402-404
The effect of the nature of the metal (Fe and Co) deposited on the surface of hydrolysis lignin, as well as the metal content (1, 3, 5 and 7 wt%), on the process of dry catalytic lignin reforming has been studied. The use of the catalyst led to a twofold increase in the conversion of carbon dioxide at temperatures of 500–800 °C, while both metals showed similar activity. The maximum specific catalytic effect is achieved when supporting 7 wt% of active metals.  相似文献   

14.
《Mendeleev Communications》2020,30(2):195-197
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15.
ABSTRACT

Vicinal diols are important building blocks for chemicals and pharmaceuticals. Currently, they are produced from olefins using solvents and harmful oxidants unfavorable from an environmental and economic point of view. This work lies on the synthesis of 1,2 cyclohexane diol from cyclohexene by a green route. To achieve it, a series of Cobalt Keggin heteropolyanion salt (Co1.5PW12O40) loaded on activated carbon with different contents was prepared, characterized and tested for the synthesis of diol. The effect of various parameters such as reaction temperature, reaction time and CO2 pressure on the reaction was studied. The effect of reaction temperature in the range 60-80 °C showed that high temperatures favor diol formation while low temperatures favor cyclohexanone and a segmented concave Arrhenius graph was observed. The results of this work showed that oxidation by H2O2 in the presence of CO2 is an efficient oxidant system for the production of 1.2 cyclohexane diol over carbon activated carbon supported Co1.5PW12O40. Thanks to CO2 as a soft oxidizing agent, a conversion of 96.9% and a selectivity in 1, 2 cyclohexane diol of 64.2% was obtained. This simple, safe and environmentally method could be an alternative green route for vicinal diols production from alkenes.  相似文献   

16.
用浸渍法分别得到含5%Na2CO3、5%NaHCO3、5%NaOH(质量比)的改性活性炭。研究了改性活性炭在含CO2原料气中的脱硫性能。在固定床反应器上考察了有氧条件下浸渍剂、反应温度和原料气湿度对SO2的脱除影响。分别在常温(25℃)和高温(350℃)下详细考察了原料气中的CO2含量对活性炭脱硫性能的影响。实验表明,常温(25℃)下,CO2的存在对活性炭脱硫有不利的影响;高温(350℃)下,CO2的存在对活性炭脱硫有促进作用。  相似文献   

17.
许峥  张鎏  张继炎 《催化学报》2001,22(1):18-22
用动态热重技术和色谱技术联用以及XRD和TEM等表征手段,研究了Ni/γ-Al2O3催化剂上甲烷-二氧化碳重整体系的积碳和消碳及其与一氧化碳产率之间的关系。结果表明,二氧化碳与甲烷有不同的活性中心,二氧化碳的存在不改变甲烷活化积碳的本质,但可通过及时将表面含碳物种转化为一氧化碳而降低积碳速率,二氧化碳能消去活泼的须状碳,但不易消去惰性的石墨碳。等摩尔条件下二氧化碳消碳能力弱于甲烷活化积碳,二氧化碳适度过量可有效抑制积碳,n(CO2)/n(CH4)≈1.3为进料比最佳值,此时积碳-消碳达到动态平衡,可获得最高的一氧化碳产率和较低的积碳速率,且该值不受温度影响。Ni/γ-Al2O3催化剂有很强的再生能力,但反复积碳-消碳会使催化剂镍晶粒度增大,分散度下降,从而导致不可逆失活。  相似文献   

18.
Thermolysis of the nitride‐bridged diuranium(IV) complex Cs{(μ‐N)[U(OSi(OtBu)3)3]2} ( 1 ) showed that the bridging nitride behaves as a strong nucleophile, promoting N?C bond formation by siloxide ligand fragmentation to yield an imido‐bridged siloxide/silanediolate diuranium(IV) complex, Cs{(μ‐NtBu)(μ‐O2Si(OtBu)2)U2(OSi(OtBu)3)5}. Complex 1 displayed reactivity towards CS2 and CO2 at room temperature that is unprecedented in f‐element chemistry, affording diverse N‐functionalized products depending on the reaction stoichiometry. The reaction of 1 with two equivalents of CS2 yielded the thiocyanate/thiocarbonate complex Cs{(μ‐NCS)(μ‐CS3)[U(OSi(OtBu)3)3]2} via a putative NCS?/S2? intermediate. The reaction of 1 with one equivalent of CO2 resulted in deoxygenation and N?C bond formation, yielding the cyanate/oxo complex Cs{(μ‐NCO)(μ‐O)[U(OSi(OtBu)3)3]2}. Addition of excess CO2 to 1 led to the unprecedented dicarbamate product Cs{(μ‐NC2O4)[U(OSi(OtBu)3)3]2}.  相似文献   

19.
The hydride-bridged silylium cation [Et3Si−H−SiEt3]+, stabilized by the weakly coordinating [Me3NB12Cl11] anion, undergoes, in the presence of excess silane, a series of unexpected consecutive reactions with the valence-isoelectronic molecules CS2 and CO2. The final products of the reaction with CS2 are methane and the previously unknown [(Et3Si)3S]+ cation. To gain insight into the entire reaction cascade, numerous experiments with varying conditions were performed, intermediate products were intercepted, and their structures were determined by X-ray crystallography. Besides the [(Et3Si)3S]+ cation as the final product, crystal structures of [(Et3Si)2SMe]+, [Et3SiS(H)Me]+, and [Et3SiOC(H)OSiEt3]+ were obtained. Experimental results combined with supporting quantum-chemical calculations in the gas phase and solution allow a detailed understanding of the reaction cascade.  相似文献   

20.
This work presents a novel approach in synthesizing copper (Cu)/carbon composite materials by electrodeposition of the biopolymer chitosan, a renewable carbon precursor, on a copper anode, followed by pyrolysis of the electrodeposited chitosan gel. The amount of copper in the Cu/carbon composite material can be controlled by modifying the pH of the chitosan solution from which the electrodeposition is performed. This further influences the physical properties of the composite material. Here we show a 14 fold increase in electrical conductivity of the Cu/carbon composite, when compared to the material without copper inclusions. Metal/carbon composite materials have a wide range of applications already reported in the literature. As a proof of concept, we demonstrate the electrochemical sensing capability of this Cu/carbon material for non-enzymatic detection of hydrogen peroxide, achieving a sensitivity of 58.9 μA/mM cm2, which is comparable to state of the art non-enzymatic hydrogen peroxide sensors. The anodic electrodeposition of chitosan proves to be a simple and straightforward medium for synthesis of Cu/carbon composites. We speculate that this method can be extended to obtain other metal/carbon composites as a low-cost alternative for the fabrication of functional composite electrodes.  相似文献   

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