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1.
Adolfo Parmaliana Valerii Sokolovskii Francesco Arena Francesco Frusteri Danila Miceli 《Catalysis Letters》1996,40(1-2):105-108
The oxidative dehydrogenation of propane to propylene with molecular O2 (PPD) has been investigated on commercial bare SiO2 and medium loaded V2O5 and MoO3 catalysts at 450–525°C. The direct relationship between the density of reduced sites (, 1016 sr g
cat–
1
), evaluated in steady-state conditions by O2 chemisorption, and the POD reaction rate proves the occurrence of a concerted reaction mechanism involving the activation of gas-phase O2 on the reduced sites of the catalyst surface. A straight-line correlation between the activity of such silica based catalysts in POD and methane partial oxidation to formaldehyde (MPO) at 525°C has been disclosed. 相似文献
2.
The effect of magnesia loading and preparation procedure of vanadia on
titania catalysts on the physicochemical characteristics and the
performance in propane oxidative dehydrogenation were investigated. A
series of magnesia promoted vanadia catalyst (5 wt% V2O5) with varying amounts of MgO (1.9--10 wt%) were synthesized by
synchronous and sequential deposition on titania support. The catalysts
were characterized using several techniques (BET, XRD, H2-TPR and NH3)-TPD). Both MgO loading and preparation procedure affect the catalyst surface properties and the behavior in the oxidative
dehydrogenation of propane. Magnesia addition results in drastic
increase in propene selectivity, while the effect on activity is
negative. The activity is inversely related with the magnesia loading.
Deposition of V2O5 on previously prepared MgO/TiO2 presents a beneficial effect in the activity of the sample. The role of acidity and reducibility is explored. There is no correlation between
reducibility and activity of the catalysts, whereas the acidity seems to influence the catalytic performance. Catalyst containing 5 wt% V2O5 and 1.9 wt% MgO prepared by sequential deposition of
V2O5 on already doped with MgO titania exhibits the most interesting results. 相似文献
3.
Patricia Concepción José M. López Nieto Joaquín Pérez-Pariente 《Catalysis Letters》1993,19(4):333-337
VAPO-5 and V/ ALPO-5 catalysts have been tested for the oxidative dehydrogenation of propane. Depending on the vanadium contents and the preparation procedure, different vanadium species and different catalytic behavior are observed. The catalyst containing V5+ species with a tetrahedral coordination presents the higher yield of propene in the oxidative dehydrogenation of propane. The same yields of CO2 are observed on all vanadium aluminophosphate catalysts, while the higher the yield of propene the lower the yield of CO is. 相似文献
4.
How oxide carriers affect the reactivity of V2O5 catalysts in the oxidative dehydrogenation of propane 总被引:1,自引:0,他引:1
The catalytic pattern of several oxide carriers (MgO, Al2O3, ZrO2, TiO2, SiO2, HY zeolite) and supported V2O5 (4.7–5.3 wt%) catalysts in the oxidative dehydrogenation of propane to propylene (PODH) has been comparatively investigated.
The fundamental role of the oxide support on both reducibility and reactivity of vanadia catalysts has been assessed. A direct
relationship between the specific surface activity of oxide carriers and that of vanadia catalysts is discussed. The inverse
relationship between the specific activity and the onset temperature of reduction marks the prevailing redox behaviour of
V2O5 catalysts in the PODH reaction.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
随着对丙烯需求的日渐增加,由丙烷催化脱氢制丙烯来实现对丙烯的增产,已成为增产丙烯的重要手段之一。利用水热法制备一系列不同Sn掺杂量的Sn-MFI载体,采用等体积浸渍法制备相同Pt负载量的Pt/Sn-MFI催化剂,通过XRD、N2吸附-脱附、FT-IR和H2-TPR等表征考察不同Sn掺杂量的催化剂对丙烷催化脱氢性能的影响。结果表明,Pt/Sn1. 3%-MFI催化剂具有最高的催化丙烷脱氢活性和稳定性,丙烷初始转化率为43. 3%,丙烯选择性为98. 9%。反应360 min后,丙烷转化率为25. 1%,选择性保持不变。 相似文献
6.
R. Grabowski B. Grzybowska A. Kozłowska J. Słoczyński K. Wcisło Y. Barbaux 《Topics in Catalysis》1996,3(3-4):277-288
The effect of alkali metal additives Li, K, and Rb to V2O5/TiO2 catalyst on the rate of catalyst reduction with propane and reoxidation with oxygen, sorption of propene, and the electron work function has been examined. The results have been correlated with the catalytic performance in oxidative dehydrogenation, ODH, of propane. It has been found that the rates of reduction, reoxidation and the ODH of propane decrease in the order: VTi>LiVTi>KVTi>RbVTi. The activation energies of the reduction and reoxidation are not, however, affected by the presence of the alkali metals. The same sequence has been observed for the work function values of the catalysts. It is argued that alkali metal poisons the centres of the hydrocarbon activation. The yield and selectivity to propene in the ODH of propane increase, however, for the promoted catalysts, following the above sequence. This effect is ascribed to the decrease in the heat of the propene adsorption, which is due to the increase in the basicity and decrease in acidity on the promoted catalysts. 相似文献
7.
柱撑型钒基催化剂的制备及其丙烷氧化脱氢催化性能 总被引:1,自引:0,他引:1
以人工合成的3种不同层板组成的层状双羟基金属氢氧化物MgAl-CO3-LDHs、CoAl-CO3-LDHs和NiCr-CO3-LDHs为载体,以偏钒酸钠NaVO3为柱撑剂和钒前体,采用离子交换法制备了钒柱撑的催化剂样品(MgAlVO、CoAlVO和NiCrVO),通过XRD、FTIR、XPS和Raman等手段表征了样品的物相、钒物种的存在形态以及钒的价态,以丙烷氧化脱氢制丙烯为模型反应,表征了所制备的催化剂样品的催化性能,着重探讨了LDHs载体的层板组成以及钒的含量对催化剂样品中的钒氧物种存在形态及其丙烷氧化脱氢催化性能的影响。结果表明:以20%理论含量的钒柱撑MgAl-CO3-LDHs所制备的催化剂样品20%MgAlVO对丙烷氧化脱氢反应的催化性能较好,当反应温度为560℃时,丙烯收率可以达到11.3%,Raman光谱显示该催化剂样品中的钒以Mg3V2O8和α-Mg2V2O7两种形式共存,且晶格氧O2-和吸附氧O-所占的比例较为均衡,有利于获得较好的丙烷氧化脱氢催化性能,而在同样条件下制备的催化剂样品20%CoAlVO和20%NiCrVO中的钒物种只观察到分别以Co3V2O8和Ni3V2O8存在的正钒酸盐,前者对丙烯的收率不到8%,后者甚至完全得不到丙烯。 相似文献
8.
9.
The catalytic performances of Mn-based catalysts have been investigated for the oxidative dehydrogenation of both ethane (ODE)
and propane (ODP). The results show that a LiCl/MnOx/PC (Portland cement) catalyst has an excellent catalytic performance for oxidative dehydrogenation of both ethane and propane
to ethylene and propylene, more than 60% alkanes conversion and more than 80% olefins selectivity could be achieved at 650°C.
In addition, the results indicate that Mn-based catalysts belong to p-type semiconductors, the electrical conductivity of
which is the main factor in influencing the olefins selectivity. Lithium, chlorine and PC in the LiCl/MnOx/PC catalyst are all necessary components to keep the excellent catalytic performance at a low temperature.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
M. Guidotti V. Dal Santo A. Gallo E. Gianotti G. Peli R. Psaro L. Sordelli 《Catalysis Letters》2006,112(1-2):89-95
The dehydrogenation of propane was studied in gas-phase at 773 K over two series of silica-deposited Ir–Sn systems: the bimetallic
catalysts obtained from Ir–Sn carbonyl clusters precursors and the ones prepared by deposition of a metallorganic Sn precursor
onto preformed Ir nanoparticles. In the comparison, cluster-derived catalysts showed good propane conversion, optimal selectivity
to propene and high stability under the severe reaction conditions. 相似文献
11.
以β分子筛为载体,通过浸渍法负载钼制备MoO3/β分子筛催化剂,对其进行XRD、FT-IR、BET和NH3-TPD物化性能表征,考察其对丙烷氧化脱氢制丙烯的催化性能。结果表明,样品具有活性组分MoO3存在,也有不同酸性能的活性位存在。负载量对催化剂的表面积和孔径有影响。单纯β分子筛载体有催化活性,不同钼负载量对催化性能有影响,负载钼质量分数为20%时,转化率达到极大值。 相似文献
12.
13.
Effect of calcium and potassium on V2O5/ZrO2 catalyst for oxidative dehydrogenation of propane: a comparative study 总被引:1,自引:0,他引:1
The effect of calcium and potassium on the physiochemical properties and performance of V2O5/ZrO2 catalyst for oxidative dehydrogenation of propane was studied in the temperature range of 385–400 °C. The vanadia loading was kept constant at 5 VOx/nm2 and the atomic ratio A/V (A=Ca, K) was varied from 0.05 to 0.75. The vanadia surface structure was investigated using X-ray diffraction analysis (XRD), electron paramagnetic resonance (EPR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The redox property of the catalysts was studied by temperature programmed reduction (TPR) and temperature programmed oxidation (TPO) whereas surface acidity was measured by temperature programmed desorption (TPD) of ammonia. Calcium and potassium both interact with the surface V=O and stabilize the +5 oxidation state of vanadium. Interaction between calcium and vanadium was more intense though surface concentration of calcium was lower than that of potassium. For doped catalysts, the activity was lower due to an increase in reduction temperature as well as a lower extent of reduction and increased resistance to undergo redox cycles. On the other hand, removal of surface acidic sites by the dopants increased the propene selectivity. Potassium was more effective in decreasing the activity and increasing the propene selectivity. 相似文献
14.
Catalytic activities of magnesium molybdates were investigated for the oxidative dehydrogenation of propane with and without molecular oxygen under atmospheric pressure. Catalytic properties drastically changed with the catalyst composition, and it turned out that Mg0.95MoOx catalysts having slight excess molybdenum showed the highest activity in the oxidative dehydrogenation of propane, which gave 61% selectivity to propene at 22% conversion of propane at 515°C. The catalytic activities strongly depended on the acidic properties of the catalysts. It was also revealed that the lattice oxide ions of the catalysts participated as an active oxygen in the oxidative dehydrogenation of propane. 相似文献
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16.
José Santamaría-González Joaquín Luque-Zambrana Josefa Mérida-Robles Pedro Maireles-Torres Enrique Rodríguez-Castellón Antonio Jiménez-López 《Catalysis Letters》2000,68(1-2):67-73
Three series of vanadium-containing silica catalysts (2–7.6 wt% V) have been prepared by varying the synthesis method. In
all cases, conversion values in the oxidative dehydrogenation of propane increase with the temperature, vanadium loading and
reducibility. For impregnated and anchored catalysts, a relationship between the selectivity towards propene and the effective
acidity, as determined in the dehydration of 2-propanol, can be established.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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CeO2‐CrOy loaded on γ‐Al2O3 was investigated in this work for the oxidative dehydrogenation (ODH) of propane under oxygen‐free conditions. The ODH experiments of propane were conducted in a fluidized bed at 500°C‐600°C under 0.1 Mpa. The prepared catalyst was characterized by N2 adsorption‐desorption measurements, H2‐temperature‐programmed reduction, O2‐temperature‐programmed desorption, NH3‐temperature‐programmed desorption, x‐ray photoelectron spectroscopy, and x‐ray diffraction. The change in the selectivity of propylene resulted from the thermal cracking of the propane and the competition for lattice oxygen in the catalyst between propylene formation and propane and propylene combustion. Therefore, to achieve higher propylene yield in the industry, the reaction temperature should be 550°C‐575°C for the 17.5Cr‐2Ce/Al catalyst. The results of H2‐TPR (from 0.2218 mmol/g‐0.3208 mmol/g) revealed that the addition of CeO2 can enhance the oxygen capacity of CrOy. Compared with that for 17.5Cr/Al, the conversion can be enhanced from 22.4% to 28.5% and the selectivity of propylene can be improved from 72.2% to 75.9% for the 17.5Cr‐2Ce/Al catalyst. In addition, CeO2 can inhibit the evolution of lattice oxygen (O2?) to electrophilic oxygen species (O2?), causing the average COx (CO and CO2) selectivity to decrease from 9.64% to 6.31%. 相似文献