Ref 8 chemical reaction engineering

Chemical Reaction Engineering atomic level pellet level laboratory level Reaction Mechanism and Kinetics Chemical Transformation Organic, inorganic, bio-chemistries Catalysis Catalysis, advanced material, surface science Measurements Physical and analytical chemistries Analysis Mathematical modeling production level Catalyst and Reactor Design Material, Energy and Momentum Balances Chemical engineering processes, Thermodynamics and fluid mechanics Transport Kinetics Mass and heat transfer Scale-up Scale-up of technical reactor Reactor Operation and Control Control of reactor processes Chemical Transformation -1 Free Radical Chain Polymerization Initiation (1) thermal or photochemical (2) chemical initiators Chemical Transformation -1 Free Radical Chain Polymerization Propagation Chemical Transformation -1 Free Radical Chain Polymerization Termination Chemical Transformation -1 Magnitude of Reaction Parameters Chemical Transformation -1 Free Radical Chain Polymerization Other Reactions Chain Transfer (1.1) Give two more reactions that can be found in free-radical chain polymerization Chemical Transformation -2 Sol-gel Process Silica nanoparticles Hydrolysis Si(OCH2CH3)4 + H2O (HO)Si(OCH2CH3)3 (HO)2Si(OCH2CH3)2 (HO)3Si(OCH2CH3) Si(OH)4 (1.2) Condensation can be catalyzed by acid or base, please describe the reaction Chemical Transformation -2 Sol-gel Process Silica nanoparticles Condensation (HO)Si(OCH2CH3)3 (CH3CH2O)3 Si-O-Si(OCH2CH3)3 Si(OR)2 (RO)2 Si Si(OR)2 (RO)2 Si-O-Si(OR)2 OO Si(OR)2 (RO)2 Si (1.3) List all possible oligomers for (a) silica and (b) zeolite Chemical Transformation -2 Sol-gel Process Silica nanoparticles Polymerization Si OSi SiO SiO SiO OSi SiO Si SiO SiO SiO OSi SiO SiO SiO SiO Si Si OSi SiO Polymerization lead to formation of silica nanoparticles Chemical Transformation -2 Sol-gel Process Silica nanoparticles Crystallization? nanoparticles Si Si OSi SiO SiO Si SiO OSi SiO Si OSi SiO SiO SiO SiO SiO OSi SiO SiO SiO Si SiO OSi SiO SiO agglomerates powder Chemical Transformation -2 Sol-gel Process Silica nanoparticles Phase transformation Chemical Transformation -3 Solar Energy Conversion in Chloroplast Typical Plant Cell Chloroplast Chemical Transformation -3 Solar Energy Conversion in Chloroplast Thylakoid Membrane hυ H2O + NaDP+ H+ + ADP3- + Pi H+ + O2 + NaDPH ATP4- + H2O CO2 + 18 ATP4- + 12 NaDPH + 12 H2O H+ + C6H12O6 + 18 ADP3- + 18 Pi + 12 NaDP+ (1.4) Describe ATP production by mitochondrion Catalysis Catalyst speed up the rate of reaction by lowering the activation energy (Ea) It does not change the thermodynamics of the reaction, It equally speed up the forward and reverse reactions, It may undergo transformation during reaction, but is not consumed by the reaction (1.5) What are the other characteristics of a catalyst? Catalysis Heterogenous Catalysis Ziegler-Natta Group IV or VIII Cocatalyst Group III Catalysis Homogenous Catalysis Metallocene (1.6) Describe the metallocene catalysts for isotactic, syndiotactic and atactic polypropylene Heterogenous Catalysis Surface Processes Adsorption, diffusion, surface reaction and desorption Ammonia N2 H2 N2 (g) + 1.5 H2 (g) N2 (ads) + 1.5 H2 (ads) N≡H3 NH2 (ads) + H (ads) → NH (ads) + H (ads) → N (ads) + H (ads) Heterogenous Catalysis Heterogenous Catalysts Reactions occurs on the catalyst surface, therefore a large surface area is advantageous Dispersed Catalysts Highly dispersed metal on metal oxide highest Nickel clusters lowest SiO2 55 atom cluster surface energy minimization http://brian.ch.cam.ac.uk/~jon/PhD2/node19.html Heterogenous Catalysis CENG 511 (Spring 04) Preparation Characterization Testing Structure Bulk: XRD, XAS, NMR Surface: GA-XRD, FIM, TEM, AFM Morphology: Microscopies Chemistry Bulk: XRD, XRF Surface: XPS, AES, SIMS, FTIR Localized: EDXS, EPM Electronic ESR, UV-Vis, IR, XPS Screening Combinatorial screening Laboratory Reactor Batch, differential and integral In-situ Reaction Reaction conducted under direct observation Energy Balances o Standard Heat of Formation (∆Hf ) The change in enthalpy associated with any chemical reaction that involves the creation of a molecule from elements in their standard state is called the heat of formation C(s) + O2(g, STP) → CO2 (g, STP) C + OO → Energy Balances Standard Heat of Formation CO2 Energy Balances Standard Heat of Combustion Energy Balances Constant Pressure Energy Balances Constant Volume (Ideal Gas) (2.1) Derive the above equation from the general energy balance equation for a batch reactor Energy Balances Constant Volume vs Constant Pressure Energy Balances Liquid phase batch reactor – The exothermic elementary liquid phase reaction: was carried out in a batch reactor with a cooling coil to keep the reactor isothermal at 27C The reactor was filled with mol/L of reactant A (a) How long does it take to reach 95 % conversion? (b) What is the total amount of heat (kcal) removed by the cooling coil when this conversion is reached? (c) What is the maximum rate by which the heat must be removed by the heating coil (kcal/min) and at what time does this maximum occurs? (d) What is the adiabatic temperature rise for this reactor and its significance? Energy Balances Liquid phase batch reactor – Additional information: (2.2) Repeat the calculation for a second order irreversible reaction: Energy Balances First Order Reaction Kinetics 0.8 Conversion (X ) CA (M) 1.5 0.6 0.4 0.5 0.2 0 100 200 300 400 100 200 300 400 time (s) time (s) Energy Balances Heat Removal by Cooling Coil 30000 500 400 -Q (kcal) -Q (kcal/s) 20000 300 200 10000 100 0 100 200 time (s) 300 400 100 200 time (s) 300 400 Energy Balances Adiabatic Heating and Temperature Rise 250 300 20 10 Ea = kcal/mol Temperature (C) ∆T (K) 200 150 100 200 100 50 0 0.2 0.4 0.6 0.8 Conversion (X ) 10 12 14 time (min) Energy Balances Runaway Reaction 1 20 Isothermal 0.8 Conversion (X ) Conversion (X ) 0.8 10 0.6 0.4 0.2 Ea = kcal/mol 0.6 0.4 0.2 0 50 100 150 time (min) 200 250 time (min) 10 12 14 Thermodynamics Chemical Reaction Equilibrium Why study chemical reaction equilibrium when operating reactors are never at chemical equilibrium? (1) Determine the limits of reactor performance, (2) Explore possible design and operation changes that overcomes these restriction and optimizes reactor performance Thermodynamics Gibbs Energy (∆G) Physical and Chemical Precondition for Biochemical Reactions including Cell Metabolism and Enzymatic Catalysis UNCATALYZED ENZYMATICALLY CATALYZED Thermodynamics ∆G < Spontaneous, Energy releasing process – Exergonic Process ∆G = Equilibrium process ∆G > Non-spontaneous, Energy consuming process – Endergonic Process Energy (Photon, Heat) cell metabolism STORED ENERGY Nutrient (Reduced molecules) http://www.biologie.uni-hamburg.de/b-online/e18/18.htm Thermodynamics Cell Metabolism Work by using exergonic processes to drive endergonic processes ATP is an important source of energy Thermodynamics Semiconductor Processing Reaction Equilibrium is harnessed in microelectronic fabrications Chemical Vapor Deposition Thermodynamics Chemical Vapor Deposition Thermodynamics Chemical Vapor Deposition and Etching Reaction Equilibrium is harnessed in microelectronic fabrications Thermodynamics Thermodynamic System The equilibrium state of the system is completely defined once the temperature, pressure and moles of each components are specified The Gibbs free energy of the system (G) is the convenient energy function of these state variables Thermodynamics Condition for Reaction Equilibrium The Gibbs free energy: Extend of Reaction Thermodynamics Condition for Reaction Equilibrium The Gibbs free energy: Extend of Reaction Thermodynamics Condition for Reaction Equilibrium Standard Gibbs energy activity Necessary condition for reaction equilibrium Thermodynamics Condition for Reaction Equilibrium The Gibbs free energy for a reaction system: Standard Gibbs energy of change Equilibrium constant fugacity Thermodynamics Ideal Gas Equilibrium – High octane fuel additives are produced by reaction of isobutane with 1-butene hydrocarbons: Determine the equilibrium composition of the reaction mixture at a pressure of 2.5 atm and temperature of 400 K The standard Gibbs energy change for this reaction at 400 K is –3.72 kcal/mol Assume that equimolar amounts of isobutane and 1-butene are present in the initial mixture (2.3) Please repeat the calculation if the initial ratio of I/B = 100, 10, 0.1 Thermodynamics Modified Gibbs Energy Single reaction Thermodynamics Modified Gibbs Energy ε’ = 0.469 ... Reaction TS-1 H2O2 + 1-pentene 1-epoxypentene + H2O k’ = kcB0 cB0 >> cA0 Material Balances (1 .8) Derive the reaction equation for a second order reversible reaction (A to 2B) Plot CA/CA0 vs reaction. .. 200 250 time (min) 10 12 14 Thermodynamics Chemical Reaction Equilibrium Why study chemical reaction equilibrium when operating reactors are never at chemical equilibrium? (1) Determine the limits... for Reaction Equilibrium The Gibbs free energy: Extend of Reaction Thermodynamics Condition for Reaction Equilibrium The Gibbs free energy: Extend of Reaction Thermodynamics Condition for Reaction