纳米NiO催化乙烷低温氧化脱氢制乙烯

 用溶胶-凝胶法制备了纳米氧化镍。TEM结果表明，在380℃下焙烧的氧化镍粒子大小在10 nm以下。与大尺寸氧化镍相比，纳米氧化镍对乙烷氧化脱氢反应的催化性能有较大的改善，在获得相当收率时反应温度大约下降125℃。关于热点问题，可以通过催化剂与石英沙混合得到解决。     

负载型氧化镍催化剂上的乙烷氧化脱氢TiO2对Al2O3载体的改性作用

自从丁烷取代苯制顺厅烯二酸酐工业化以来,低碳烷烃的选择氧化越来越受到重视.     

纳米Cr2O3系列催化剂上CO2氧化乙烷脱氢制乙烯反应

 采用溶胶－凝胶法和共沸蒸馏法耦合技术制备了纳米Cr2O3催化剂，并采用共沉淀法和共沸蒸馏法耦合技术制备了纳米Cr2O3／Al2O3，Cr2O3／ZrO2和Cr2O3／MgO复合催化剂．应用BET，XRD，XPS，TPR和TEM等物理化学方法对催化剂的结构和物化性质进行了表征，并考察了该系列催化剂上CO2氧化乙烷脱氢制乙烯的反应性能．结果表明，纳米Cr2O3催化剂上乙烷和CO2的转化率均明显高于常规Cr2O3催化剂，但乙烯的选择性低于常规Cr2O3催化剂；纳米复合催化剂中的复合成分显著影响催化剂的催化性能．其中，10％Cr2O3／MgO纳米复合催化剂在温度为973K时，乙烷转化率和乙烯选择性分别可达到61．54％和94．79％．纳米催化剂表面Cr的还原性以及Cr6＋／Cr3＋比值是影响乙烷转化率和乙烯选择性的重要因素．     

介孔Ni基催化剂上乙烷氧化脱氢制乙烯

以十二烷基硫酸钠为模板剂,尿素为沉淀剂制备了介孔氧化镍,并将该方法成功拓展至介孔NiMgO催化剂的合成.考察了这两种催化剂以及采用溶胶.凝胶法制备的纳米氧化镍催化剂对乙烷氧化脱氢反应的催化性能.结果表明,介孔氧化镍较纳米氧化镍在相同乙烷转化率条件下乙烯选择性更高,且前者反应温区大为扩展,因而乙烯收率更高.介孔氧化镍经Mg调变后,其催化性能进一步提高,在450℃,C2H6:O2:N2=1:1:4和GHSV=18000ml/(g.h)条件下,介孔NiMgO催化剂上乙烷转化率和乙烯收率分别为56.6%和30.1%,其乙烯收率远高于纳米氧化镍(15.9%)和介孔氧化镍(22.5%).     

Oxidative Dehydrogenation of Ethane to Ethylene over LiCl/MnOx/PC Catalysts

The catalytic stability of LiCl/MnO_x/PC catalyst have been investigated, the deactivation mechanism was discussed. The experimental results show that ethane conversion decreases and ethylene selectivity keeps about 90% as reaction time increases. The main deactivation reasons of LiCl/MnO_x/PC catalyst for oxidative dehydrogenation of ethane (ODHE) to ethylene are the transition of active species Mn₂O₃ to MnO species and the loss of active component Cl in catalyst. Instead of ethane with FCC tailed‐gas, the stability of LiCl/MnO_x/PC catalyst has been largely improved.     

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.     

Surface Acidity/Basicity and Catalytic Reactivity of CeO2/γ-Al2O3 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%CeO2/γ-Al2O3. The selectivity to ethylene was high for all the CeO2, γ-Al2O3 and CeO2/γ-Al2O3 catalysts.     

Surface Acidity/Basicity and Catalytic Reactivity of CeO2/7-Al2O3 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 microcalori-metric 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-A12O3. 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%CeO2/γ-Al2O3. The selectivity to ethylene was high for all the CeO2,γ-A12O3 and CeO2/γ-Al2O3 catalysts.     

Pd-Cu/γ-Al_2O_3催化苯乙炔选择性加氢反应

为了提高苯乙炔加氢反应中的苯乙烯选择性,本文采用"胶体-等体积浸渍"两步法制备了Pd-Cu/γ-Al2O3双金属催化剂.利用高分辨率透射电镜(HRTEM)、X射线光电子能谱(XPS)、CO脉冲化学吸附、N2物理吸附、电感耦合等离子体原子发射光谱(ICP-AES)等技术表征了Pd-Cu/γ-Al2O3的结构性质,考察了Cu/Pd摩尔比、Pd负载量以及金属引入顺序对Pd-Cu/γ-Al2O3催化苯乙炔选择性加氢性能的影响.结果表明,与Pd/γ-Al2O3单金属催化剂相比,Pd-Cu/γ-Al2O3的苯乙烯选择性大幅度提高,尤其是当Pd负载量为0.3%(w),且Cu/Pd摩尔比为0.6时,Pd-Cu/γ-Al2O3表现出优异的加氢选择性;在0.1 MPa和40°C下,当苯乙炔转化率为90%时,双金属催化剂的苯乙烯选择性可达95%;当转化率达到99%以上时,苯乙烯选择性仍保持在82%左右.分析表明,Pd-Cu/γ-Al2O3中形成了Pd-Cu合金,但是两种金属间不存在电子转移,Cu对Pd的几何效应才是导致Pd-Cu/γ-Al2O3苯乙烯选择性增加的主要原因.     

LiCl／SO4^2——ZrO2催化剂上乙烷氧化脱氢制乙烯

用辅以回流处理的两步法制备硫酸化氧化锆(SO2-4ZrO2),再用浸渍法制备Li质量含量为0.5%～15%的LiCl/SO2-4ZrO2催化剂.650℃时,在Li含量为15%的催化剂上,获得了90.6%的乙烷转化率、85.9%的乙烯选择性和77.8%的乙烯收率,在24h的实验考察中,乙烯的收率一直保持在71%以上.采用X射线粉末衍射、低温N2吸附、程序升温脱附和X射线光电子能谱等对催化剂的体相结构、比表面积、表面酸碱性和表面元素组成等进行了表征.结果表明,LiCl的添加使催化剂中四方相ZrO2的含量降低,比表面积减小,表面酸性减弱,乙烷氧化脱氢催化性能明显提高,但ZrO2的体相结构对其催化性能没有明显影响.随着反应时间的延长,LiCl慢慢流失,催化剂的乙烯选择性逐渐下降.与未经回流处理制得的硫酸化二氧化锆相比,采用回流处理后的ZrO2制得的SO2-4ZrO2具有较大的比表面积,单位质量的样品可负载更多的LiCl,有利于延缓催化剂活性因LiCl流失而下降.     

LiCl/SO2-4-ZrO2催化剂上乙烷氧化脱氢制乙烯

 用辅以回流处理的两步法制备硫酸化氧化锆(SO2-4-ZrO2), 再用浸渍法制备Li质量含量为0.5%～15%的LiCl/SO2-4-ZrO2催化剂. 650 ℃时,在Li含量为15%的催化剂上,获得了90.6%的乙烷转化率、85.9%的乙烯选择性和77.8%的乙烯收率,在24 h的实验考察中,乙烯的收率一直保持在71%以上. 采用X射线粉末衍射、低温N2吸附、程序升温脱附和X射线光电子能谱等对催化剂的体相结构、比表面积、表面酸碱性和表面元素组成等进行了表征. 结果表明, LiCl的添加使催化剂中四方相ZrO2的含量降低,比表面积减小,表面酸性减弱,乙烷氧化脱氢催化性能明显提高,但ZrO2的体相结构对其催化性能没有明显影响. 随着反应时间的延长, LiCl慢慢流失,催化剂的乙烯选择性逐渐下降. 与未经回流处理制得的硫酸化二氧化锆相比,采用回流处理后的ZrO2制得的SO2-4-ZrO2具有较大的比表面积,单位质量的样品可负载更多的LiCl, 有利于延缓催化剂活性因LiCl流失而下降.     

乙烷在纳米氧化镍上温和氧化脱氢制乙烯

用溶胶-凝胶法制备的纳米氧化镍具有较好的乙烷氧化脱氢低温反应活性.380℃下焙烧的NiO粒子大小在8 nm左右,与大尺寸氧化镍相比,获得相同收率时反应温度大约下降125℃.并通过BET,TPR,TPD,XPS等手段对不同焙烧温度的氧化镍催化剂进行表征,研究其粒子大小与对氧的活化能力及反应活性的关联.     

乙烷氧化脱氢制乙烯反应中制备方法及助剂对镍基催化剂性能的影响

采用不同方法制备了镍基催化剂,并考察了乙烷氧化脱氢制乙烯(ODE)的反应活性,结果表明,在3种不同制备方法的催化剂上,ODE反应的活性及产物选择性存在明显差异,浸渍法制备的催化剂性能最佳.在相同的条件下,以共浸渍法引入CeO2助剂后,N iO/-γA l2O3催化剂上的低温选择氧化活性显著提高,而目的产物C2H4的选择性变化不大.XRD,还原TG和XPS对催化剂进行表征的结果显示:反应的活性物相可能是易于还原的高度分散于催化剂表面的微晶N iO和表面尖晶石N iA l2O4物相;高分散的微晶N iO,类似于纯N iO,有利于ODE反应低温选择氧化生成目的产物C2H4,而易还原的表面尖晶石N iA l2O4物相的存在则可能是在高温下获得高选择氧化活性和选择性的主要原因之一.     

Effects of Preparation Methods and Interaction between Support and Oxide for Oxidative Dehydrogenation of Ethane over NiO/ZrO2

The previous studies indicated that the unsupported and alumina supported nickel oxide catalysts are the attractive candidates for the oxidative dehydrogenation of ethane (ODE) reaction at lower reaction temperature^[1,2]. In the present study, NiO/ZrO₂ catalysts were prepared by the impregnation, complex of ammonia and coprecipitation, respectively, using the conventional incipient wetness technique. Over all samples used in this study, no NiO crystal structure was detected by XRD measurements carried out in parallel with the present work, which indicated the nickel oxide was highly dispersed on the support The blank testing indicated that the support ZrO₂ had very little activity below 600℃. Comparing with the unsupported nickel oxide, it was found that the activity of NiO/ZrO₂ catalysts prepared by the methods mentioned above decreased slightly and the selectivity for ethylene improved. With the increasing temperature, the ethane conversion increased and the selectivity for ethylene decreased However, the cracking of the ethane occurred at ca.450℃ on all samples prepared by different methods. The optimum catalytic behavior could be obtained on 5wt%NiO/ZrO₂ prepared by coprecipitation, with the ethane conversion of 26.2% and selectivity for ethylene of 51.8% at as low temperature as 350℃. The sample prepared by coprecipitation and calcined at 500℃ was calcined again at 600℃ for 5 h,the activity decreased obviously, which may be attributed to the existence of the interaction between nickel oxide and support taking into account for the high dispersion of NiO on ZiO₂.     

掺杂钛酸盐对乙烷氧化脱氢催化性能的研究

在７００￣８５０℃范围内研究了掺杂ＣａＴｉＯ３、ＳｒＴｉＯ３催化剂用于乙烷氧化脱氢（ＯＤＨＥ）的催化行为，发现这类催化剂对ＯＤＨＥ均有一定的催化活性。适量的Ｌｉ＾＋取代Ｔｉ＾４＋后不仅提高了催化活性，而且改善了催化剂对乙烯的选择性。催化剂ＣａＴｉ０．９Ｌｉ０．１Ｏ３－δ在８５０℃时乙烷转化率和乙烯选择性分别为８７．８％和７１．７％。Ｓｒ对Ｃａ部分取代后制得的催化剂可在极宽的温度范围内（７００￣８５     

乙烷氧化脱氢制乙烯CeO2-NiO/A2O3催化剂上氧物种的研究

在镍基催化剂上进行了乙烷氧化脱氢制乙烯的研究.结果表明,浸渍法制备的催化剂性能最佳.以浸渍法引入CeO2后,催化剂的低温反应活性显著提高.采用O2-TPD-MS、TPR和XPS等表征技术对催化剂进行了表征,结果显示:在ODE反应中,在低温下起主导作用的是"非化学计量氧"(O2-、O-和O22-);在高温下起主导作用的是晶格氧;CeO2的添加减弱了NiO与载体-γAl2O3间的强相互作用,提高了镍物种在载体上的分散度,高分散于催化剂表面的微晶NiO的量明显增加,此物种有利于催化剂的低温活性;影响了催化剂表面氧物种的分布,表面的晶格氧的相对浓度提高了,非化学计量氧的相对浓度降低了.     

钴基催化剂上乙烷氧化脱氢的催化作用

比较了氧化钴、氧化镍分别对乙烯、乙烷氧化的催化性能,结果发现：乙烯在氧化钴较氧化镍上更易进一步深度氧化生成CO2．通过对新制担载型Co-基催化剂随反应温度反复升、降温的乙烷氧化脱氢(ODHE)性能研究,展现了氧化钴活性相与SiO2载体相互作用对催化性能的影响．Weiss原位磁研究结果表明：SiO2担载的氧化钴催化剂较难还原,即使在反应气中氧被完全耗完时,钴仍停留在Co^2 的价态上．通过对数十个担载和未担载、不同载体、不同担载量的Co-基催化剂的ODHE性能考察表明：在Co-基催化剂上ODHE反应机理一般遵从Hetero-homogeneous机理．     

h-BN掺杂Na2WO4-Mn/SiO2催化剂用于乙烷氧化脱氢制乙烯

采用混浆法制备了一系列六方氮化硼掺杂的Na2WO4/Mn/BxSiy催化剂,并应用于乙烷氧化脱氢制乙烯（ODHE）。考察了Na2WO4/Mn/BxSiy催化剂的ODHE反应性能,并详细探讨了反应温度、稀释气比例等条件对催化剂反应活性的影响。结果表明,h-BN的掺杂发现显著提高了Na2WO4/Mn/BxSiy催化剂C2H4选择性。Na2WO4/Mn/B5.0Si95催化剂在700℃时,表现出相对较高的活性并且CO2生成量极低（>70% 乙烯选择性,46.5%的乙烯收率,1.80%的CO2选择性）。通过X-射线粉末衍射（XRD）、扫描电镜（SEM）、H2程序升温还原（H2-TPR）、O2程序升温脱附（O2-TPD）和C2H6程序升温脱附（C2H6-TPD）等手段对催化剂进行了表征。研究发现,h-BN的加入对改变催化剂表面元素的化学状态,形成了更多具有低温活性的物相,对抑制深度氧化起到重要作用。同时,h-BN的掺杂也调变了催化剂的导热能力,避免床层热点的形成,提高了C2H4的选择性。     

Effect of SO2 on the NO Oxidation over NiO/γAl2O3 Catalyst

NO is the dominant component of NO_x. It can be easily oxidized to NO₂ over active catalysts in the oxidizing exhaust gases. And then, the high reactive NO₂ can be removed completely further through adsorption or absorption approach. However, SO₂,another main contaminant in the exhaust, is well known to poison the oxidative catalysts. A strong deactivation for metal oxides supported on Al₂O₃ was found when catalysts had been exposed to the gas containing 500ppm SO₂. It was also reported that the inhibition effect of SO₂ was enhanced at low temperatures. But recently, some studies declare that the oxidation of propane can be promoted over Pt/γ-Al₂O₃ if a small amount of SO₂ (20 ppm) is present in the feed gas^[1]. Jang et al. have also found that SO₂ has a promoting effect for the oxidation of NO to NO₂ over CO₃O₄/γ-Al₂O₃ catalyst^[2]. These observations are meaningful because the existence of SO₂ in the oxidizing exhaust is often inevitable and the problem of catalyst deactivation by SO₂ has puzzled researchers for a long time.     

K助剂对Pt-Sn-K/γ-Al2O3催化剂上C16正构烷烃脱氢反应的影响

 以络合真空浸渍法制备了 Pt-Sn-K/γ-Al2O3 催化剂. 采用吡啶吸附红外光谱、CO脉冲吸附、程序升温还原、热重及程序升温氧化等手段对催化剂进行了表征, 研究了 K 助剂对 Pt-Sn-K/γ-Al2O3 催化剂结构及其催化 C16 正烷烃临氢脱氢反应性能的影响. 结果表明, K 的引入减弱了 SnOx 和 Al2O3 间的相互作用, 促进了 Pt 对 SnOx 的还原, 并导致催化剂的脱氢反应活性降低. K 的加入还减少了强酸中心数目, 一方面减少了催化剂酸性位上的副反应, 提高了产物选择性; 另一方面提高了催化剂的抗积炭能力, 催化剂稳定性有所改善. 但过量的 K 助剂减弱了催化剂的金属位-酸性位的协同作用, 使得催化剂活性和稳定性均有所降低.