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研究了甲烷氧化偶联六组分Na-W-Mn-Zr-S-P/SiO_2催化剂对乙烷氧化脱氢反应的催化性能.考察了不同原料气配比、温度和空速等条件下的催化剂活性.讨论了催化剂中S或P组分的含量对催化活性的影响.实验结果表明,S和P元素的加入可以提高催化剂的活性.660℃时六组分催化剂上乙烷的转化率为65.2%,乙烯的选择性为83.2%,此时得到的乙烯收率最高.乙烷与氧气比的增加有利于提高乙烯的选择性.较低反应温度时,空速的增加可以抑制碳氧化物(CO,CO_2)的生成,提高乙烯选择性. 相似文献
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Rui Zhou Yong Cao Shirun Yan Jingfa Deng Yuanyan Liao Bifeng Hong 《Catalysis Letters》2001,75(1-2):107-112
Vanadium-containing mesoporous HMS catalysts have been prepared and characterized for the oxidative dehydrogenation (ODH) of propane. It is demonstrated that the vanadium supported HMS catalysts exhibit a much higher catalytic activity than the literature results obtained over the vanadium supported MCM-41 catalysts in the ODH of propane. The improved catalytic activity of the V-HMS catalysts has been attributed to the presence of high concentration of well-dispersed vanadium species on the surface of the mesoporous HMS materials. 相似文献
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Highly Effective Oxidative Dehydrogenation of Propane Over Vanadia Supported on Mesoporous SBA-15 Silica 总被引:1,自引:0,他引:1
Vanadia-containing mesoporous SBA-15 catalysts were prepared and characterized for the oxidative dehydrogenation (ODH) of propane. It is demonstrated that the vanadia-supported SBA-15 catalysts exhibit a much higher catalytic activity than those reported in the literature obtained over vanadium-supported mesoporous MCM-41 catalysts in the ODH of propane. The high catalytic performance of the mesoporous SBA-15 catalysts is attributed to the particularly large pore diameters and low surface acidity. 相似文献
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The effect of MoO3 loading on the properties and the catalytic performance of a series of alumina-supported molybdena catalysts (0–30 wt% MoO3) was investigated in the oxidative dehydrogenation of ethane. The molybdena species on alumina were found to be amorphous at submonolayer coverages. At higher loadings, the formation of Al2(MoO4)3 crystallites was detected by XRD. XPS revealed the existence of both Mo(VI) and Mo(V) sites on the catalyst surface, the concentration of which depends on the MoO3 loading. In terms of catalytic performance, the activity increases with increasing loading in the submonolayer regime, decreasing for higher loadings. High selectivity to ethene is obtained even at relatively high conversion levels for catalysts exceeding monolayer coverage. 相似文献
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L. Lisi L. Marchese H.O. Pastore A. Frache G. Ruoppolo G. Russo 《Topics in Catalysis》2003,22(1-2):95-99
Acid silicoaluminophosphate SAPO-34 catalysts with a chabasite-related (CHA) structure were tested for the oxidative dehydrogenation of ethane in the temperature range 550-700 °C achieving very interesting catalytic performances (about 70% C2H4 selectivity at 45% ethane conversion) which were related to both Lewis and Brønsted acid sites, as found by a NH3-TPD study. 相似文献
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研究合成原料中酚物种的调控对有机-有机自组装方式合成的介孔碳材料(MC-X)结构和性能的影响,通过氮气吸脱附、透射电镜(TEM)、热重分析(TGA)和惰性气体程序升温脱附(TPD)等手段表征MC-X的结构、化学热稳定性和表面基团种类和含量,并将该系列催化剂应用于1-丁烯的氧化脱氢反应中。结果表明,MC-X具有不同的介孔结构,其中以单聚物为前驱体的介孔碳具有有序结构,MC-3具有较高的化学热稳定性。碳材料的氧化脱氢性能与其表面基团物种及其含量密切相关,在相同的碳化条件下,介孔碳表面C=O基团含量越高(如MC-3),其1,3-丁二烯选择性和收率也越高。进一步分析表明,C=O和C-O基团含量的比值与1,3-丁二烯选择性呈正相关,C=O基团的总量与1,3-丁二烯收率呈正相关。 相似文献
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Daniell W. Ponchel A. Kuba S. Anderle F. Weingand T. Gregory D.H. Knözinger H. 《Topics in Catalysis》2002,20(1-4):65-74
A series of ceria-supported vanadium catalysts was prepared via impregnation of the support with an ammonium metavanadate solution. The 723 K calcined samples were tested for propane oxydehydrogenation (ODH) activity and selectivity. The sample exhibiting the highest propane conversion was found to be the ceria support material itself, although this showed essentially no selectivity towards propene. An optimum propene yield of 4.2% was obtained at 673 K for the 6 wt% V2O5-CeO2 sample. Conversion decreased with increasing V loading which was attributed to the formation of cerium vanadate (CeVO4). This phase was found in all samples after calcination, its abundance rising in proportion to the V loading. In the 6 wt% V2O5 catalyst hydrated surface VOx species were present, although they underwent conversion to CeVO4 at temperatures above 573 K. The low reducibility of these surface vanadates was linked to the oxidation activity. It is inferred that surface polyvanadate species are responsible for the selective ODH of propane with V-O-V and/or V-O-Ce being the active oxygen species. 相似文献
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An oxygen permeable mixed ion and electron conducting membrane (OPMIECM) was used as an oxygen transfer medium as well as a catalyst for the oxidative dehydrogenation of ethane to produce ethylene. O2- species transported through the membrane reacted with ethane to produce ethylene before it recombined to gaseous O2, so that the deep oxidation of the products was greatly suppressed. As a result, 80% selectivity of ethylene at 84% ethane conversion was achieved, whereas 53.7% ethylene selectivity was obtained using a conventional fixed-bed reactor under the same reaction conditions with the same catalyst at 800 °C. A 100 h continuous operation of this process was carried out and the result indicates the feasibility for practical applications. 相似文献
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Dehydrogenation of Light Alkanes Over Rhenium Catalysts on Conventional and Mesoporous MFI Supports 总被引:1,自引:0,他引:1
Anne Krogh Rovik Anke Hagen Iver Schmidt Søren Dahl Ib Chorkendorff Claus Hviid Christensen 《Catalysis Letters》2006,109(3-4):153-156
Recently, Re/HZSM-5 (Si/Al = 15) was shown to be an efficient catalyst for ethane dehydrogenation and aromatization at 823 K
and atmospheric pressure. In this reaction, the major initial products were benzene, toluene and xylene (BTX), but increasing
amounts of ethene were produced with time on stream due to deactivation of the catalyst. We show that by use of rhenium impregnated
MFI supports with very few or no acidic sites (Si/Al > 500), highly selective ethane dehydrogenation catalysts are obtained
with ethene selectivities of 98%. By use of mesoporous MFI supports (Si/Al >500) the lifetime of the catalyst appears to be
slightly improved compared to conventional MFI crystals. The beneficial effect of a mesoporous MFI support is convincingly
demonstrated in propane dehydrogenation, where both conversion and selectivities on the mesoporous MFI (Si/Al > 500) impregnated
with Re are significantly higher than on Re supported on a comparable conventional MFI support. 相似文献
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乙苯氧化脱氢制苯乙烯催化机理及催化过程分析 总被引:1,自引:0,他引:1
采用乙苯氧化脱氢过程不仅可以突破热力学平衡的限制, 并且降低了生产过程的能耗。该过程的关键是开发出高活性及高选择性的催化剂。以V-Mg-O为代表的金属氧化物型催化剂遵循典型的Redox机理。影响催化剂性能的主要因素有催化剂的晶相组成、表面电子特性和表面酸行, 同时工艺条件诸如反应温度、O2浓度、EB空速及水蒸汽用量等也影响着催化剂的性能, 其中催化剂的晶相组成起着决定性作用。 相似文献
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Vanadium and/or magnesium substituted aluminophosphate with ALPO4-5 structure have been prepared by hydrothermal synthesis. These catalysts have been tested for the oxidative dehydrogenation (ODH) of ethane. ALPO4-5 has a low activity and low selectivity for the ODH of ethane. The presence of Mg2+ ions in MgAPO-5 increases the selectivity to ethene, while the presence of V5+ species in VAPO-5 increases both the activity and the selectivity for this reaction. The presence of Mg2+ and V5+ species in the vanadium-magnesium alumino-phosphate (MgVAPO-5) results in a more selective catalysts for the ODH of ethane. The behavior of MgVAPO-5 could be attributed to the presence of acid sites (Mg2+) near to the redox sites (V5+) in the molecular sieve framework. 相似文献
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The oxidative dehydrogenation of butane to butadiene and butene was studied using a conventional fixed-bed ractor (FBR), inert membrane reactor (IMR) and mixed inert membrane reactor (MIMR). When IMR and MIMR were employed, a ceramic membrane modified by partially coating with glaze was used to distribute oxygen to a fixed-bed of 24-V-Mg-O catalyst. The oxygen partial pressure in the catalyst bed could be decreased. The effect of feeding modes and operation conditions were investigated. The selectivity of C4 dehydrogenation products (bntene and bntadiene) was found to be higher in IMR than in FBR. The feeding mode with 20% of air mixing with butane in MIMR was found to be more efficient than the feeding mode with all air permeating through ceramic membrane. The MIMR gave the most smooth temperature profile along the bed. 相似文献
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Oxidative dehydrogenation of n-butane on V/MgO catalysts. Influence of the type of contactor 总被引:2,自引:0,他引:2
J. Soler J.M. López Nieto J. Herguido M. Menéndez J. Santamaría 《Catalysis Letters》1998,50(1-2):25-30
A comparative study of the catalytic performance of a selective V-Mg-O catalyst in the oxidative dehydrogenation of n-butane
is presented using three different types of reactor: (i) an adiabatic fixed-bed reactor; (ii) a fluidized-bed reactor; and
(iii) an in situ redox fluidized-bed reactor. The results obtained indicate that the in situ redox fluidized-bed reactor outperforms
the conventional fixed- and fluidized-bed reactors, especially at high n-butane conversions. Thus, a selectivity to C4 olefins of 54% at n-butane conversions of 60% was achieved at 550°C using an in situ redox fluidized-bed reactor while selectivities
to C4-olefins lower than 43% were obtained on the other reactor types under the same reaction conditions (isoconversion and reaction
temperature).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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The oxidative dehydrogenation of propane was investigated in a fixed-bed tubular flow reactor at 350 and 450°C over V–Mg–O catalysts prepared via a solid reaction (the mix-VMg catalysts) or from mesoporous precursors (the meso-VMg catalysts). Significantly higher selectivities and yields to propene were obtained over the meso-VMg catalysts than over the mix-VMg ones. The cooperation between a much higher BET specific surface area and a novel phase, a highly dispersed-Mg-in-V2O3, is suggested as responsible for the higher ODP performance of the meso-VMg catalysts than of the mix-VMg ones. 相似文献
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Chromium Oxide Supported on Mesoporous SBA-15 as Propane Dehydrogenation and Oxidative Dehydrogenation Catalysts 总被引:3,自引:0,他引:3
The catalytic activity and selectivity of Cr2O3 supported on mesoporous SBA-15 for non-oxidative and oxidative dehydrogenation of propane by O2 and CO2 have been studied and compared with those of Cr2O3/ZrO2 and Cr2O3/-Al2O3 catalysts. Cr2O3/SBA-15 and Cr2O3/ZrO2/SBA-15 are more selective to propene and more resistant to coking in comparison with Cr2O3/ZrO2 and Cr2O3/-Al2O3 for non-oxidative dehydrogenation of propane. In oxidative dehydrogenation of propane by O2 and CO2, Cr2O3/SBA-15 also displays better activity, selectivity and stability than the other two supported catalysts. The propane conversion and propene yield on Cr2O3/SBA-15 catalyst for oxidative dehydrogenation of propane by CO2 at 823 K reach 24.2 and 20.3%, respectively. XPS and TG/DTA have been used to characterize the catalysts before and after reaction. The differences in catalytic behavior of various supported Cr2O3 catalysts in the reactions have been discussed on the basis of the characterization results. 相似文献
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Fuchs Stefan Leveles Laszlo Seshan K. Lefferts Leon Lemonidou Angeliki Lercher Johannes A. 《Topics in Catalysis》2001,15(2-4):169-174
The oxidative dehydrogenation and cracking of ethane and propane over LiDyMg mixed oxides is reported. High yields of olefins and only moderate formation of carbon oxides was observed. Both are primary products that hardly interconvert under the reaction conditions used. Addition of chloride increases the rate of reaction, while slightly decreasing the selectivity to olefins. The addition of carbon dioxide strongly decreases the rate of reaction, the negative order of 0.5 indicating that two active Li+sites are blocked by the adsorption of one CO2molecule. The reaction proceeds at low oxygen pressure primarily via elimination of dihydrogen, while at higher oxygen partial pressure the hydrogen elimination occurs via water formation. It is speculated that dehydrogenation and cracking involve Li+and a rather nucleophilic oxygen site. 相似文献
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Sam Bergh Peijun Cong Bren Ehnebuske Shenheng Guan Alfred Hagemeyer Hong Lin Yumin Liu Claus G. Lugmair Howard W. Turner Anthony F. Volpe Jr. W. Henry Weinberg Lenny Woo Jessica Zysk 《Topics in Catalysis》2003,23(1-4):65-79
The application of combinatorial methods to three reactions catalyzed by multimetal oxides is described. Catalysts for the oxidative dehydrogenation of ethane to ethylene were tested using a 121- or 144-channel scanning mass spectrometer primary screening reactor and a 48-channel fixed bed secondary screening reactor; catalysts for the selective oxidation of ethane to acetic acid were tested using a 256-channel massively parallel microfluidic reactor primary screen alone, and catalysts for the selective ammoxidation of propane to acrylonitrile were tested using the massively parallel microfluidic reactor and an eight-channel fixed bed secondary/tertiary screening reactor. The details regarding catalyst design, synthesis, and screening are presented. This work has resulted in both the confirmation of published results and the generation of new lead materials for all three chemistries. 相似文献
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