Kinetics of Oxidative Dehydrogenation of Propance over a VMgO Catalyst

The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550oC over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts for the dehydrogenation of propane to propylene. Selectivity to propylene up to about 60% was obtained at 10% conversion, but the selectivity decreased with increasing conversion. No oxygenates were detected, the only by-products were CO and CO2. The reaction rate of propane was found to be first order in propane and close to zero order in oxygen, which is in agreement with a Mars van Krevelen mechanism with the activation of the hydrocarbon as the rate determining step. The activation energy of the conversion of propane was found to be 122±6 kJ/mol.     

Effect of Different Dopant in the Mo-V-Te-O Catalyst on the Performance of Selective Oxidation Propane to Acrolein

Several Mo-V-Te-O mixed metal oxides catalysts with different dopant were prepared and used for catalytic oxidation propane to acrolein. It was revealed that the addition of P could greatly improve the performance of the Mo-V-Te-O catalyst. The catalysts were examined by XRD and H2-TPR. The XRD characteristic of the Mo-V-Te-P-O showed that the addition of P could aggrandize the (V0.07Mo0.93)5O14 phase. H2-TPR illuminated that the MoV0.3Te0.23P0.15On catalyst took on the best redox ability.     

Low Temperature Oxidative Dehydrogenation of Ethane to Ethylene Catalyzed by Nano—sized NiO

Theselectiveoxidationofalkanesintotheircor respondingolefinshasattractedgreatinterestinre centyears .Ethaneisthesecondmajorcomponentofnaturalgas .Theindustrial productionofethylenefromlightalkanessuchasethaneusesthermalpyroly sisbyhigh temperaturesteam ,whichiscostlyinen ergy[1] .Manyattemptshavebeenmadetoreplacethisprocessbythecatalyticoxidativedehydrogena tionofethane (ODE) .MostcatalystsfortheODEreactionarelarge sizedmaterials ,andthereactiontemperaturesarehigh .Forexample ,theC2 H4 yie…     

Influence of Addition of ZnO on Property of Fe2O3-K2O System Catalyst for Ethylbenzene Dehydrogenation to Styrene

The incorporation of ZnO into Fe2O3-K2O system increases its activity, enhances its moisture stability and mechanical strength. The origin of the enhancement in activity and moisture stability is discussed in the light of experimental results obtained by BET, XRD, XPS. It was found that the addition of ZnO to Fe2O3-K2O system strengthens the interaction between Fe2O3 and K2O, reduces the formation temperature of KFe11O17 at least by 50℃, and promotes the transformation of Fe^3 to Fe^2 further.     

Study on Bifunctionality of Mo／HZSM—5 Catalysts for Methane Dehydro—Aromatization under Non—oxidative Condition

The optimum Mo/[H^ ] ratio per unit cell of the active precursors in Mo/HZSM-5 catalysts for methane dehydro-aromatization,measured by ^1H MAS NMR,was found to be about 1 when adjusting the acid sites by altering either the SiO2/Al2O3 ration or the Mo loading,This implies that a concerted interaction between the Mo species and the Broensted acid sites probably features the bifunctionality of the Mo/HZSM-5 catalyst,On the other hand,it was found that the driving force for Mo species to move into the HSZM-5 zeolite channels and the interaction between the Mo species and the Broensted acid sites are closely and proportionably realtaed with the amount of Broensted acid sites per unit cell.     

Surface Acidity／Basicity and Catalytic Reactivity of CeO2／γ—A12O3 Catalysts for the Oxidative Dehydrogenation of Ethane with Carbon Dioxide to Ethylene

Dehydrogenation of ethane to ethylene in CO2 was investigated over CeO2/γ-Al2O3 catalysts at 700℃ in a conventional flow reactor operating at atmospheric pressure. XRD, BET and microcalorimetric adsorption techniques were used to characterize the structure and surface acidity/basicity of the CeO2/γ-Al2O3 catalysts. The results show that the surface acidity decreased while the surface basicity increased after the addition of CeO2 to γ-Al2O3. Accordingly, the activity of the hydrogenation reaction of CO2 increased, which might be responsible for the enhanced conversion in the dehydrogenation of ethane to ethylene. The highest ethane conversion obtained was about 15% for the 25?O2/γ-Al2O3. The selectivity to ethylene was high for all the CeO2, γ-Al2O3 and CeO2/γ-Al2O3 catalysts.     

丙烯选择氧化反应中钼基催化剂动态结构的研究

 用原位共焦显微拉曼光谱技术考察了丙烷选择氧化反应中Ag－M\r\no－P－O催化剂的结构，讨论了催化剂动态结构的成因及其对催化剂性\r\n能的影响．实验结果表明，在773K和n（C3H8）∶n（O2）∶n（N2）＝\r\n3∶1∶4的反应条件下，Ag－Mo－P－O催化剂中的Mo－O物种可转化为A\r\ngMoO2PO4中的Mo－O物种（多钼酸根），此时催化剂对丙烷选择氧化具\r\n有较高的催化活性．催化剂中Mo－O物种的转化是由MoO3中Mo－O物种和\r\nAgMoO2PO4中Mo－O物种的结构特性决定的．AgMoO2PO4中的Mo－O物种具\r\n有较强的参与MarsvanKrevelen氧化－还原循环的能力，可能是丙烷选\r\n择氧化反应的活性物种．     

丙烷氧化脱氢氧化物催化剂的活性氧物种

研究了半导体金属氧化物催化剂丙烷氧化脱氧制丙烯的性能，发现p-型半导体金属氧化物有低温催化性能，n-型半导体金属氧化物有高温催化性能，H2－TPR，O2－TPD－MS和原位电导研究结果表明，p-型半导体金属氧化物的活性氧物种为非化学计量氧物种，n-型半导体的活性氧物种为表面晶格氧。     

钼掺杂LaVO4上丙烷氧化脱氢

研究了钼掺杂LaVO4催化剂的丙烷氧化脱氢催化性能.加入钼对丙烷氧化脱氢反应有很好的助催化作用.当丙烷转化率恒定在10％和20％时，丙烯选择性在LaMo0.1V0.9O4.05上分别达到了56％和43％，而在LaVO4上仅为36％和22％，这归结为钼掺杂催化剂上有利于丙烯生成的可活动氧物种的增加和催化剂氧化还原性的改变.     

丙烷氧化脱氢催化剂Ag-Mo-P-O中MoO3的作用

用XRD、H2-TPR、XPS、EPR、NH3-DRIFT、异丙醇分解反应和催化剂性能评价等方法比较研究了一系列Ag-Mo-P-O(AMP)催化剂的性质和催化性能.实验结果表明,AMP催化剂中MoO3和AgMoO2PO4两相之间产生由“一致性界面”引起的协同效应,两相相互作用的程度和接触程度影响该协同效应.该协同效应调变了催化剂中Mo5＋的浓度、催化剂的可还原性和酸性,从而影响了丙烷氧化脱氢制丙烯催化剂的性能.在AMP催化剂中存在适量的MoO3有助于获得较高的丙烯选择性和收率.     

Kinetics of the Oxidative Dehydrogenation of Propane over a VMgO Catalyst

The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550℃over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts forthe dehydrogenation of propane to propylene. Selectivity to propylene up to about 60% was obtained at10% conversion, but the selectivity decreased with increasing conversion. No oxygenates were detected, theonly by-products were CO and CO2. The reaction rate of propane was found to be first order in propaneand close to zero order in oxygen, which is in agreement with a Mars van Krevelen mechanism with theactivation of the hydrocarbon as the rate determining step. The activation energy of the conversion ofpropane was found to be 122±6 kJ/mol.     

Kinetics of the Oxidative Dehydrogenation of Propane over a VMgO Catalyst

The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550℃ over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts for the dehydrogenation of propane to propylene. Selectivity to propylene up to about 60% was obtained at 10% conversion, but the selectivity decreased with increasing conversion. No oxygenates were detected, the only by-products were CO and CO2. The reaction rate of propane was found to be first order in propane and close to zero order in oxygen, which is in agreement with a Mars van Krevelen mechanism with the activation of the hydrocarbon as the rate determining step. The activation energy of the conversion of propane was found to be 122±6 kJ/mol.     

Oxidative Dehydrogenation of Propane to Propene over Barium Promoted Ni-Mo-O Catalyst

Oxidative dehydrogenation of propane to propene was investigated over Ba- promoted Ni_0.9MoO₄ catalysts (molar ratio of Ba/Mo: 1%, 3%, 6%, 9%, 12%, 15%). The selectivity for propene increases with the increasing number of basic sites on the catalyst, and molybdenum ions play an important role in propane activation. No significant deactivation of the 6% Ba- Ni_0.9MoO₄ and Ni_0.9MoO₄ at 773 K for 80 h and for 40 h, respectively, appeared, indicating that the 6% Ba- Ni_0.9MoO₄ has great advantage over the Ni_0.9MoO₄. This revised version was published online in June 2006 with corrections to the Cover Date.     

介孔氧化铝负载钒催化剂上丙烷氧化脱氢制丙烯

 采用浸渍法制备了介孔氧化铝 (m-Al2O3) 负载钒催化剂 (V/m-Al2O3), 并考察了其催化丙烷氧化脱氢制丙烯反应活性. 通过 N2 吸附-脱附、透射电镜、X 射线粉末衍射、紫外-可见漫反射光谱、氢-程序升温还原和氨-程序升温脱附对催化剂进行了表征. 结果表明, 介孔氧化铝具有大比表面积、窄孔径分布和两维六方相结构, 在其上负载适量的 V 可实现 V 活性物种的高分散及催化剂的弱酸性, 从而有利于提高丙烷转化率和丙烯选择性. 与共合成法制备的含 V 介孔氧化铝 V/m-Al2O3(C) 和浸渍法制备的 V/?-Al2O3 相比, V/m-Al2O3 表现出更高的催化活性. 这与载体较弱的酸性和较大的比表面积以及 V 物种的高分散有关.     

纯稀土基丙烷氧化脱氢制丙烯催化剂的研究

轻质烷烃广泛存在于天然气、炼厂气及油田气中,对其合理利用正日益引起重视。催化研究工作者试图通过研制合适的催化剂将其转化为更有用的化工原料,如烯烃或舍氧有机物等。丙烷氧化脱氢制丙烯是该研究的一部分。目前已报道的丙烷氧化脱氢催化剂大都是钒基催化剂,如V-Mg-O体系,但这些催化剂的选择性较差,特别是在转化率较高时其选择性更差。本文报道的纯稀土基催化剂采用新型活性中心调变剂和隔离剂,其组份少、热稳定性高,在高转化率时仍具有较好的选择性。