不同结构的分子筛在1-丁烯中催化裂解性能的研究

我们合成了不同Si含量的SAPO-18,并且利用了XRD、SEM、NH3-TPD进行了表征分析.利用微反固定床反应器评价了代表不同结构的H-ZSM-5(MFI)、H-Beta(* BEA)、SAPO-18 (AEI)系列分子筛的丁烯催化裂解性能.实验结果表明分子筛的结构和酸性对反应结果都有明显影响,分子筛酸量的增加提高了1-丁烯的转化率,但酸量过高会引发氢转移、芳构化副反应,从而降低丙烯的选择性;分子筛孔口大小、孔道结构决定了可以获得的最高丙烯选择性.具有八元环孔口、笼形结构特点的SAPO-18-0.8在线时间20 min时1-丁烯裂解中转化率为60.7％,获得的丙烯选择性达到59.1％.     

FT-IR Study of the Adsorption of Propane and Propene on V2O5/γ-Al2O3 Catalyst

It has been observed on the oxidized V₂ O₅/γ-Al₂ O₃ that C₃H₆ form alkoxides which were converted to acetone during the desorption of adsorbate phase at 373 K. C₃ H₈ may form π-complexes on the reduced form of the same catalyst. However, the intensities of the bands in the adadsorption of C₃ H₈ were very weak as compared with the case of C₃ H₆ adsorption. Therefore, it was not reasonable to assign these bands clearly as any of the surface type species.     

Ni-Ti-O混合氧化物的制备、表征及其富氧选择性催化还原NO

采用均匀共沉淀法制备了不同Ni/Ti摩尔比的Ni-Ti-O混合氧化物,考察了它们在富氧条件下丙烯选择性催化还原NO反应中的催化性能,并运用X射线衍射,N₂吸附-脱附、吡啶吸附、程序升温脱附和原位红外光谱对催化剂进行了表征.结果表明,Ni/Ti摩尔比为1的催化剂表现出最佳催化活性,430℃时NO_x转化率达68%.该催化剂具有锐钛矿结构,比表面积较高(149m²/g),有利于提高催化活性;其表面Lewis酸性位有利于硝酸盐物种的吸附,而硝酸盐物种是该反应的重要中间体.     

Ab initio anharmonic force field and equilibrium structure of propene

The quadratic, cubic and semi-diagonal quartic force field of propene has been calculated at the MP2 level of theory employing a basis set of triple-ζ quality. A semi-experimental equilibrium structure has been derived from experimental ground state rotational constants and rovibrational interaction parameters calculated from the ab initio force field. This structure is in excellent agreement with the ab initio structure calculated at the CCSD(T) level of theory using a basis set of quintuple-ζ quality and a core correlation correction. The experimental mass-dependent r_m structures are also determined and their accuracy is discussed. The use of isolated CH stretching frequencies is shown to be a good method to determine CH bond length.     

Theoretical Study of CH3CH=CH2+O(1D) Reaction: Mechanism and Kinetics

The mechanism and kinetics for the reaction of propene(CH₃CH=CH₂) molecule with O(¹D) atom were investigated theoretically. The electronic structure information of the potential energy surface(PES) was obtained at the B3LYP/6-311+G(d,p) level, and the single-point energies were refined by the multi-level MCG3-MPWB method. The calculated results show that O(¹D) atom can attack CH₃CH=CH₂ via the barrierless insertion mechanism to form four energy-riched intermediates CH₃C(OH)CH₂(IM1), CH₃CHCHOH(IM2), CH₂OHCHCH₂(IM3) and cyclo- CH₂OCHCH₃(IM4), respectively, on the singlet PES. The branching ratios as well as the pressure- and temperaturedependence of various product channels for this multi-well reaction were predicted by variational transition-state and Rice-Ramsperger-Kassel-Marcus(RRKM) theories. The present results will be useful to gain a deep insight into the reaction mechanism and kinetics of CH₃CH=CH₂+O(¹D) reaction.     

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.     

自由基-分子反应:F+Propene(CH2CHCH3)的从头算研究

采用从头算CCSD(T)/6-311 G(2d,2p)//B3LYP/6-311G(d,p)方法,研究了自由基-分子反应F CH2CHCH3的各种不同的反应通道．该反应主要是通过复合物形成机制进行,即F分别加到碳碳双键的两端形成自由基复合物1和2．这两种亚稳态自由基会解离成三种产物:H C3H5F、CH3 C2H3F和HF C3H5．理论计算结果表明,生成CH3 C2H3F是反应的主要通道,而生成H C3H5F和HF C3H5对产物也有一定的贡献．这一结果和实验符合得很好．     

丙烯和甲苯的超共轭效应的理论研究

用从头算对丙烯和甲苯2个超共轭体系进行计算,结果表明甲基上氢原子参与超共轭时,其碳氢键键长增大,氢上集居数减少,丙烯、甲苯的甲基旋转势垒为7.61及0.096 kJ/mol.超共轭基作用相当于一带有孤对电子参与共轭之杂原子,超共轭体系不同构型稳定性可用M=sum from i=1 to 3(sinθ_i[sin(θ_i-α)+sinα])来表征。     

Catalytic Synthesis of Isopropyl Benzene over SO4^2-/ZrO2 -MCM-41

Introduction Owingtotheirlargeporediametersandlargesur faceareas,silicon basedmolecularsieves(M41S)have receivedmuchattention[1—5]inthefieldsofcatalytic reactions,adsorptiveseparations,andnonmetallicma terialsscience.MCM41isthemosttypicalmaterialof thisk…     

丙烷脱氢制丙烯研究进展

介绍了丙烷脱氢制丙烯的研究现状。包括丙烷催化脱氢的热力学、脱氢技术丙烷在膜反应器中脱氢及以氧气和二氧化碳作氧化剂的丙烷氧化脱氢。