HeterogeneousCatalysis.ppt

§3.1 reaction rate 3.1.1 Reaction Rate Of A Constant- Volume Reaction 3.1.2 Average Rates And Instantaneous Rates 3.1.2 average rate and instantantaneous rate 2N2O5(CCl4) §3.2 Effects Of Concentration On Reaction Rate — Rate Law Expression 3.2.1 Rate Law expression 3.2.2 Simple Experimental Method For Determining Rate Law Expression —Initial Rate 3.2.3 Quantitative Relation Between Concentration And Time A reasonable reaction mechanism meets the two requirements:  example : hydrogenation reactions Heterogeneous Catalysis Heterogeneous Catalysis Heterogeneous Catalysis Heterogeneous Catalysis §3.4 Introduction To Reaction Rate Theory And Reaction Mechanism 3.4.1 Collision Theory 3.4.2 Activated Complex Theory (Transition State Theory ) 3.4.3 Activation Theory And Reaction Rate 3.4.4 Reaction Mechanism And Elementary Reaction 3.4.1 collision theory this theory assumes that a minimum condition for two molecules A and B to react is that they must come in contact with each other in right orientation; that is ,they must collide in an effective way. Two basic conditions for effective collisions molecules have enough energy collision in right orientation Reaction between NO2and O3 Distribution of molecular energy VS. activation energy Ek Ec E fraction of activated molecules 3.4.2 Activated complex (transition state ) theory activated complex: the transition state between reactant and product for forward and reverse reaction. because it has the highest potential energy in the whole process, activated complex is not stable. transition state theory: a theory relating reaction rates and atomic or molecular energies during the conversion of reactants to product. Ex： N O O O O Its activated complex is ，it has high Eac ,so unstable. decompose to NO2 and O2 very fast energy change in a chemical reaction Ea(逆) (正) (正) Ea(逆) Eac Eac E(Ⅰ)－ reactant energy E(Ⅱ)－product energy Act