Studies on Oxidative Coupling of Methane Catalysed by Li-Ce-Sr Oxides

The conditions for catalyst preparation and coupling reaction of methane were investigated. The experimental results showed that under the catalysts the selectivity for C2 formation may reach 98.5% and the yield 28.2% (the average within the first 30 minutes). A stale selectivity and yield for C2 formation obtained after reaction for 2h were 48.4% and 20.6%, respectively. Some kinetic parameters were also determined, including activation energy and the partial pressure dependence of the catalytic reaction rates. Finally a preliminary explanation of the reaction mechanism is suggested.     

含钛MCM-48分子筛上二十碳醇氧化制二十碳酸

采用水热合成法制备含钛ＭＣＭ－４８型中孔分子筛系列催化剂，用ＩＲ和ＸＲＤ等技术对催化剂进行了表征，对α－二十碳醇氧化制α－二十碳酸反应进行了研究，对目的反应的催化性能进行了评价，并确定出反应的最佳温度和反应时间，结果表明，添加适量的Ｔｉ可提高α－二十碳酸的收率。用ＩＲ技术对目的产物进行跟踪分析，所得结果与化学检测结果一致，将反应产物的收率与分子筛催化剂的Ｌ酸进行了关联。     

Structure and catalytic properties of magnesia-supported copper salts of molybdovanadophosphoric acid

The structure and stability of magnesia-supported copper salts of molybdovanadophosphoric acid (Cu(2)PMo(11)VO(40)) were characterized by different techniques. The catalyst was prepared in ethanol by impregnation because this solvent does not hurt texture of the water-sensitive MgO and Cu(2)PMo(11)VO(40). The Keggin-type structure compound may be degraded partially to form oligomerized polyoxometalate when supported on MgO. However, the oligomers can rebuild as the Keggin structure again after thermal treatment in air or during the reaction. Meanwhile, the V atoms migrate out of the Keggin structure to form a lacunary structure, as observed by Fourier transform IR spectroscopy. Moreover, the presence of Cu(2+) as a countercation showed an affirmative influence on the migration of V atoms, and the active sites derived from the lacunary species generated after release of V from the Keggin anion. The electron paramagnetic resonance data imply that V(5+) autoreduces to V(4+) in the fresh catalyst, and during the catalytic reaction a large number of V(4+) ions are produced, which enhance the formation of O(2-) vacancies around the metal atoms. These oxygen vacancies may also improve the reoxidation function of the catalyst. This behavior is correlated to higher catalytic properties of this catalyst. The oxidative dehydrogenation of hexanol to hexanal was studied over this catalyst. After reaction at 553.2 K for 50 h, catalytic properties did not decrease and exhibited higher selectivity (>96.0%) toward hexanal.     

侧向局部加热对流的周期性

通过流体力学方程组的数值模拟,研究了侧向局部加热条件下Prandtl数Pr=0.0272时流体对流的周期性.结果表明:随着Grashof数Gr的增加,对流按稳态对流、单局部周期对流、双局部周期对流、准周期对流的顺序发展.当Gr<3.6×103时,对流为稳态;在3.6×103相似文献   

磁铅石型复合氧化物CaNiyAl12-yO19-δ的制备和性能表征

制备了一系列磁铅石型复合氧化物ＣａＮｉｙＡｌ１２－ｙＯ１９－δ（ｙ＝０．３,０．６,０．９,１．０）,并用ＸＲＤ、ＸＰＳ、ＴＰＲ和ＴＧＡ技术对其结构和性能进行了表征。结果表明,该系列复合氧化物具有相同的晶体结构和相似的还原稳定性。当Ｎｉ调变量既０〈ｙ≤１,可以获得磁铅石型复合氧化物ＣａＮｉｙＡｌ１２－ｙＯ１９－δ晶相。在７８０℃二氧化碳重整甲烷制合成气反应过程中,还原态复合氧化物ＣａＮｉｙＡｌ１２     

β-氧化铝型复合氧化物BaMAl11O19－δ催化CO2重整甲烷制合成气

过渡金属;β-氧化铝型复合氧化物BaMAl11O19－δ催化CO2重整甲烷制合成气     

异丁酸在Fe-Pb-磷酸盐催化剂上的吸附研究

本文用脉冲色谱法研究了异丁酸(IBA)在Fe-Pb-磷酸盐催化剂上的可逆吸附及不可逆吸附规律以及H₂O预吸附对IBA不可逆吸附的影响。为进一步研究异丁酸在此催化剂上吸附及氧化脱氢反应机理提供某些信息。     

在SO42-/ZrO2 上苯与丙烯的烷基化反应

Super acidic catalyst SO42-/ZrO2 was prepared and characterized by XRD,IR,and Py-IR. Selectively catalytic gas phase flow reactions of benzene and propene over the catalyst were carried out in a made-to-measure high pressure flow reactor with a thermometer and a condenser. The benzene and propene were kept in pressure tanks at 8 : 1 ratio with N2 gas at 4. 0 MPa. The reactants were pumped into the quantifier where the pressure was maintained by N2 gas at 8. 0 MPa. They were then pumped into the reaction reactor using catalytic synthesis of isopropyl benzene. The collected liquid phase products were analyzed using GC-MS. Product analyses were carried out on SE-54. The effect of the preparative condition on the catalytic synthesis of isopropyl benzene over the catalysts has been tested. The result shows that the SO42-/ZrO2 can be used as a catalyst for the title reaction,and shows higher conversion（99.2%）for the propene and higher selectivity（93.3%）for the isopropyl benzene when the catalyst is preparated in some condition.     

CuCl2-KCl-LaCl3/γ-Al2O3对乙烷氧氯化反应的催化性能

 以γ-Al2O3为载体,采用常规浸渍法制备了负载型CuCl2-KCl-LaCl3三组分催化剂,并研究了其对乙烷氧氯化反应的催化性能. 结果表明,该催化体系中乙烷的转化率较稳定,但随着反应时间的延长,氯乙烯的选择性和收率明显下降. XRD,N2吸附,TGA/DTA和XPS测试结果表明,随着反应的进行,催化剂中的活性物种Cu2+逐渐被还原成Cu+,并且积炭的产生使催化剂的比表面积和孔容积减小. 活性物种Cu2+的减少及比表面积的降低是催化剂失活的主要原因.     

在SO42-/ZrO2上苯与丙烯的烷基化反应

制备了SO42 -/ZrO2 催化剂并采用X射线衍射、红外光谱仪测定、Py IR测定等技术对其进行了表征 .反应在自制高压流动床 (具有控温和冷凝 )装置上进行 ,原料以苯∶丙烯为 8∶1的比例配置于贮罐中 ,4 .0MPaN2 恒压 ,压入计量器后 ,用 8.0MPaN2 恒压 .反应后收集的液相产物由气相色谱 质谱 (GC MS)分析 ,产物分析在SE 5 4型毛细管色谱议上进行 .考察了苯与丙烯气相流动烷基化反应以及制备条件对催化活性的影响 ,结果表明 ,适当条件下制得的SO42 -/ZrO2 催化剂可用于合成异丙苯反应 ,并有高的丙烷转化率 (99.2 % )和高的异丙苯选择性(93.3% ) .