催化剂制备与表征

Skeleton of Catalysis Investigation 催化研究体系
Introduction to this subject
Preparation, characterization and application of a catalyst is crucial to innovate a novel catalyst.是发明一个新催化剂的关键。
Organization of Catalysis
分类方法
（1）根据化学键分类
Organization of Catalysis
（2）按元素周期律分类
Organization of Catalysis
(3) 按催化剂组成及其使用功能的分类
Organization of Catalysis
* Supported transition metal salts and/or complexes;负载的过渡金属或混合 物
PdCl2, CuCl2，HgCl2, Zn3(PO4)2, Ca3(PO4)2, W(CO)6, Mo(CO)6
* Transition metal oxides and/or sulfides;过渡金属硫化物或氧化物
Characters of the Catalyst
参与化学反应 ( Contact );
改变化学反应速度( Kinetics );
不改变化学反应平衡 ( Thermodynamics ); 反应结束后状态与数量保持不变( Media ); 催化剂可以多次再生使用( Regeneration ); 不介入化学计量反应式 ( Media );
催化剂制备与表征
郭振莲 2015年6月5日
Role
In manufacture:
More
of catalysis
than 80% of the processes in the chemical
Industry, worth approximately € 1500 billion, depend on catalytic technologies.
Catalyst is usually not the same with other chemicals, especially pure chemicals.催化剂一般与其他化学品一样，特别是纯化学品。
Catalyst usually bears complicated composition and structure,
especially for heterogeneous catalyst.催化剂一般具有复杂的结构与组成。
Know-how in catalyst preparation is key to develop optimum catalyst. 知道如何制备催化剂是优化催化剂的关键。
Contents of this subject
低速
高速
Nature of Catalysis
Nature of Catalysis
表面催化过程
离开山谷 到达山谷
Nature of Catalysis
Intermediate
Product
Reactant
By product
Nature of Catalysis
1. 改变反应历程； 2. 降低活化能； 3. 改变反应速度。
Mechanism for heterogeneous Catalysis
Heterogeneous Catalysis
Heterogeneous mechanism is difficult to investigated in the laboratory. Disappearance of reactants and appearance of products are easily followed, but important features such as the rates and energetic of adsorption, structure of active sites, the nature of active intermediates, require separate experimentation using a constantly changing arsenal of techniques. 非均相机理的实验室研究非常困难。反应物的消耗和产物的生成比 较容易追踪，但许多重要的因素比如速度和吸附能，活性位结构、 活性中间体特点等需要通过大量的单因素实验来得出。 Heterogeneous catalysts are convenient to use commercially. Easily prepared solid catalyst pellets, packed in tubes through which reactants flow, satisfy process requirements for simple operation. 非均相催化剂方便工业化使用，固体催化剂颗粒容易制备，装在反 应物经过的反应管中，简单操作即可满足工艺要求。
（3）按工艺与工程特点分类
heterogeneous catalysis
多相催化
enzyme catalysis
homogeneous catalysis
均相催化
Types of catalyst
heterogeneous catalyst
homogeneous catalyst enzyme catalyst
Homogeneous Catalysis
Usually, the liquid phase is most common, with both catalyst and reactants in solution.一般来说，液相是做常见的，催化剂和反应物同存在于溶液中。 Catalysis occurs through complexing and rearrangement between molecules and ligands of the catalyst. 催化通过分子和催化剂配体间的络合及重排发生。 Reactions can be very specific, with high yields of desired products.反应是很特效 的，目的产物收率很高。 Since the mechanisms involve readily identified species, these reactions are easily studied in the laboratory with the techniques of organometallic chemistry. They are, however, difficult to operate commercially. 因为反应机理中都是很容易识别的 因素，这些反应可以简单的通过有机金属化学实验室技术进行研究。然而， 难以商业化运营。
V2O5, Cr2O3, Fe3O4, MnO2, ZnO
ZnS, PdS, CdS MoS3, WS3
Heterogeneous Catalyst
* Solid acids and/or bases; 固体酸或碱 acids: Al2O3, SiO2-Al2O3, rare earth metal salts, etc. bases: alkaline earth metal oxide, supported alkaline metals, etc. 碱土金属氧化物、负载的碱土金属等 * Non-metal oxides or mixed oxides; 非金属氧化物或混合氧化物 P2O5, B2O3, SiO2 , etc. * Zeolites (Natural and/or synthesized); 沸石（天然的或合成的） A, X, Y, ZSM-5, SAPO, MCM41S * Polymers;(聚合物） ion-exchanged resins
Definition of Catalyst
Boudart (Nature,1994) A catalyst is a substance that brings about a chemical reaction by providing a cyclic path along which reactants become products, while the catalyst is recovered at the end of the cycle.
A
special kind of fine chemical: 1$
195$
Example
In environmental control: In academic research:学术研究
Role
of Catalysis
催化裂化催化剂的变革
Role of catalysis in FCC
催化剂是一种物质，能够提供一种循环 路径使反应物发生化学反应生成产物， 在循环结束时，催化剂恢复到初始状态。
催化剂是一种能够提高达到反应平衡速度但本身并不久参与反应的 物质。
Characters of Catalyst
Characters of Catalyst
Two words can sum up the role of the catalyst. Contact and medium 接触和媒介
催化剂量明显少于反应物料量 ( Bit );
催化剂对反应应具有选择性 ( Selectivity )。
Selectivity to the Reaction Types
Selectivity to the Reaction Types
Selectivity to reactant species
物中，或者气液相反应物中。
Interfacial phenomena become important. Diffusion, adsorption, desorption all play critical roles in establishing the rate. These additional steps become difficult to separate from surface reactions. 界面现象非常重要。扩散、吸附、脱附对反应速度都起着至关重要的作 用。这些附加的步骤难以从表面反应中分离出来。
Heterogeneous Catalysis
The reactants and catalyst exist in different phase. Most commonly, solid catalysts
are used with gaseous or liquid reactants, sometimes both. 反应物和催化剂处在不同的相态。固态催化剂用于气相反应物或液相反应
Selectivity to the Reactant and Products
Selectivity to the Intermediate
Selectivity to the Products
顺反异构 双键异构 分子间氢转移 聚合或齐聚 歧化 烷基化 结焦 需增加强酸位
Nature of Catalysis
Ideal surface is not perfect
理想的表面是不完美的
扭结
阶梯空位
阶梯位
台阶吸附的原子 台阶空位
球的堆积模型表示不完美表面
Heterogeneous Catalyst
* Metals (Transition metals, IB metals);金属
Fe Co Ni Ru Rh Pd Os Ir Pt Cu Ag Au
Keck Professor of Chemical Engineering, Emeritus A catalyst is a substance that increases the rate at which a chemical reaction approaches equilibrium without itself becoming permanently involved in the reaction.
Introduction to the Catalysis
Characters of the catalyst Type of catalyst Properties of catalyst Component of catalyst
Definition of Catalyst
Ostwald (德国）的观点 催化剂是一种能够改变化学反应的速度，而它本身又不 参与最终产物的 物质。 （流行） IUPAC定义： 催化剂能够加速反应速率而不改变反应的标准Gibbs自 有焓变化。 国内新近定义 催化时加速反应速度、控制反应方向或产物构成，而不 影响化学平衡的一类作用。起这种作用的物质称为催化 剂，它不在主反应的化 学计量式中反映出来，即在反应 中不被消耗。