330 likes | 546 Views
Lecture 12. Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors in which they take place. Lecture 12 – Tuesday 2/15/2011. Multiple Reactions Selectivity and Yield Series Reactions Complex Reactions.
E N D
Lecture 12 Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors in which they take place.
Lecture 12 – Tuesday 2/15/2011 • Multiple Reactions • Selectivity and Yield • Series Reactions • Complex Reactions
4 Types of Multiple Reactions • Series: A → B → C • Parallel: A → D, A → U • Independent: A → B, C → D • Complex: A + B →C + D, A + C → E With multiple reactors, either molar flow or number of moles must be used (no conversion!)
Selectivity and Yield There are two types of selectivity and yield: Instantaneous and Overall. Selectivity Yield
Selectivity and Yield Example: DesiredProduct: To maximize the selectivity of D with respect to U run at high concentration of A and use PFR. UndesiredProduct:
Multiple Reactions Chapter 8 FlowBatch A) Mole Balance of each and every Species
Multiple Reactions Chapter 8 A) Rates: a) Ratelawfor each reaction b) Net Rates c) Relative Rates
Multiple Reactions Chapter 8 Liquid Stoichiometry: Gas Example: A → B → C (1) A → B k1 (2) B → C k2
Example: BatchSeries Reactions 1) MoleBalance: V=V0 (constant batch)
Example: BatchSeries Reactions 2) Rates: Laws Relative rates Net rates
Example: BatchSeries Reactions example: A → B → C (1) A → B (2) B → C Ci B A C 1) Mole Balance: topt t
Example: BatchSeries Reactions Laws: 2) Rates: Relative:
Example: BatchSeries Reactions Species B: 3) Combine: Species A:
Using the integrating factor, at t = 0, CB=0 Example: BatchSeries Reactions
Example: CSTR Series Reactions ABC 1) Mole Balance: what is the optimal ?
Example: CSTR Series Reactions ABC Laws: 2) Rates: Net: Relative:
Example: CSTR Series Reactions ABC 3) Combine:
Example: CSTR Series Reactions ABC Find that gives maximum concentration of B
BloodCoagulation Many metabolic reactions involve a large number of sequential reactions, such as those that occur in the coagulation of blood. Cut → Blood → Clotting Figure A. Normal Clot Coagulation of blood (picture courtesy of: Mebs, Venomous and Poisonous Animals, Medpharm, Stugart 2002, Page 305)
Cut A + B C D E F Clot