分子模拟与理论计算在多相催化研究中的应用PPT课件

1、分子模拟与理论计算在多相催化研究中的应用,王建国 焦海军 李永旺 中科院山西煤化所 ,计算化学虚拟实验室全体会议，北京，2004-10-21,研究背景,化学工业催化过程多相催化 转化率高、选择性好、可稳定运行 催化剂相适应的工艺 实验理论研究,煤化所已开展的计算模拟工作,骨干成员,主要成员及合作者,催化剂反应性能,催化剂制备与改性,孔结构与表面性质,吸附扩散反应性,大量文献工作,实验测定 分子模拟,实验关联 分子模拟 量化计算,分子筛催化剂的设计,结构规整孔道均匀,特殊的形状选择性,活性位简单明确,构形扩散无理论模型,分子筛结构、表面酸性与形状选择性,分子力学方法在分子筛研究中的应用,吸附 吸

2、附热 吸附平衡常数 吸附等温线 吸附位 扩散（MD/MC） 路径、机理（构形扩散？） 扩散系数与孔道结构关系 形状选择反应 模扳剂的选择与作用,分子筛吸附扩散反应的Monte Carlo模拟 建立了形状选择性与K、D、k的关系,Wang et al., Zeolites, 1995, 15: 288; Catal. Lett., 1995, 54: 65; 1994, 24: 395; 26: 189; Stud. Surf. Sci. Cata., 1994, 88: 525.,ZSM-5分子筛中的烷基化/歧化反应,Klemm, Wang, et al., Chem. Eng. Sci.,

3、1997, 52: 3173-3182.,吸附 吸附热 吸附平衡常数（K） 吸附等温线 吸附位置 扩散路径及与孔道关系,Adsorption, 2004, in press. J. Mol. Struct., 2004, 679: 95; Micropor. Mesopor. Mater., 2001, 43: 237 Colloids 2002, 178, 267; 2001, 175, 131; J. Phys. Chem. A, 2002, 35, 8167; J. Mol. Strcut., 2004, 674, 267,吸附扩散反应性与孔道结构、表面性质的关联,量子化学计算,ED,分

4、子筛的结构取代位置及平衡质子在MOR中的位置,虽然所研究的杂原子均可占据T3位，但由于其位于小孔内，在催化反应中并不重要,分子筛的酸性 M-ZSM-5和MOR的质子亲合势(kcal/mol ),H2O, NH3在B, Al, Ga, Fe-MOR中的吸附,研究表明，H2O的吸附均为物理吸附，而NH3则随杂原子而不同-,+ 质子化；- 物理吸附,分子筛的吸附性能,量子力学和分子力学组合方法,基本思想：把整个体系分割成三个区域 兼具量子力学的精确性和分子力学的高效性,Amines adsorption in HMOR,NH3,Me2NH,MeNH2,Me3N,吸附过程中发生了酸性质子从沸石到胺分子

5、的转移 质子化的胺离子与沸石之间存在着多重氢键作用,J. Mol. Catal., 2004, 220: 221-228.,Adsorption energies (kJ/mol), proton affinities (PA; kJ/mol), and the corresponding pKa of the conjugate acid of amines,When measured by their adsorption energies on acidic zeolites, the basicity of these amines increases as follows: NH3

6、MeNH2 Me3N Me2NH, which agrees well with the experiments, but differs from those in the gas phase (PA) and in solution (pKa).,J. Mol. Catal., 2004, submitted.,Pyridine 在ZSM-5中的吸附,Pyridine大小与ZSM-5的intersection相近，以下相互作用同时，小cluster模型不能得到合理结果。,N与质子酸中心间氢键作用 N:与电荷平衡离子间作用 Pyridine中H与骨架O间作用 Pyridine芳环与电荷平衡离

7、子间作用,channel intersection,Al,straight channel,Al,sinusoidal channel,Al,ZSM-5 的两类孔道及其交叉位,吡啶在ZSM-5分子筛中的吸附热Ed , kJ/mol,aromatics,n-paraffins,J. Phys. Chem., 2004, submitted.,RCH=CH2 + CO + H2 RCH2CH2CHO,(i) catalyst generation,(ii) olefin coordination,(iii) olefin insertion,(iv) CO coordination,(v) CO

8、insertion or carbonylation,(vi) H2 oxidative addition,(vii) aldehyde reductive elimination with catalyst regeneration,(vi) H2 coordination,Organometallics 2003, 23, 4665-4677.,HCo(CO)3 catalyzed hydroformylation of propene,HCo(CO)3 catalyzed hydroformylation of acetylene,Organometallic 2004, 23, 765

9、-773.,The proposed reaction pathways for the hydrogenation of acrolein,Organometallic 2004, 23, 2168-2178.,Adsorptions of metal cluster on regular and defect sites of the MgO (001) surface,The formation of the vacancies on the MgO (001) surfaces,J. Phys. Chem. B 2004, 108, 8359-8363.,CO Adsorption o

10、n Fe5C2(001),J. Phys. Chem. B 2004, 108, 9094-9104.,CO Adsorption on the (001), (110) and (100) surface of Fe5C2,J. Phys. Chem. B 2004, 108, 9094-9104.,Hydroformylation and isomerization of allene and propyne,Chem. Eur. J 2004, in press.,Work in progress of publication (1),Thiophene HDS,Work in prog

11、ress of publication (1),Thiophene will be first hydrogenated into 2,5-dihydrothiophene, from which Butadiene will be eliminated directly via a intramolecular way. Therefore, butadiene is the ONLY logical HSD product.,Tetrahydrothiophene will be first dehydrogenated into 2,5-dihydrothiophene, and the

12、n go to butadiene, as found experimentally,Work in progress of publication (2),CO adsorption on the Fe(111) surface,Work in progress of publication (3),At 1/3 and 1/2 ML coverage, the shallow-hollow adsorption is the most stable site, while both shallow-hollow and bridge adsorption can coexist at 1

13、ML. Energetically, the bridge site rather than the suggested deep-hollow represents the reasonable adsorption configuration. In contrast, bent CO on-top and triply capping adsorption are the most favored forms at 2 ML.,CO adsorption on the MoS2 surface,Work in progress of publication (4),The adsorption energy of high coverage shows the additivity as compared with that of one CO adsorption, and there is no significant repulsive interaction between the end-on adsorbed CO probes. No