Team #2: Kyle Lynch David Teicher Shu Xu The Partial Oxidation of Propylene to Generate Acrolein

 Project Objective  Process Background  Material Balance  Simple Kinetics and Rate Expressions  Pressure Drop and Reactor Configuration  Multiple Reactions  Energy Balance  Optimization and Conclusions

 Design a Fixed Bed Reactor (FBR) for the production of acrolein by the partial oxidation of propylene  Produce 75,000 metric tons acrolein per year  Optimize the reactor design to minimize cost

 Literature Review ◦ Research information on raw materials and products ◦ Investigate catalysts and reaction kinetics  Reactor Design ◦ Develop mole balances for multiple reactions ◦ Implement pressure drop & energy balance equations ◦ Optimize reactor

 Acrolein ◦ Raw material used for the production of pyridine, β-picoline, and some essential amino acids 1 ◦ Used for cleaning irrigation ditches, and other derivatives can be made into rubbers, glues, and polymers 2 ◦ Anti-microbial behavior  Biocide in oil well to suppress the growth of bacteria 2 ◦ million pounds produced in the U.S. in CH 2 =CH-CHO

 Industry produces acrolein by the partial oxidation of propylene using oxygen and steam  The reaction is carried out in a catalytic FBR ranging between °C 1  Gaseous products leave and are quenched by cold water, then enter absorption column for product recovery 3 CH 2 =CH-CH 3 + O 2  CH 2 =CH-CHO + H 2 O

 Design 1-Preliminary mass and energy balance  Design 2-Reactor volume using simple reaction rate expression  Design 3-Pressure drop and reactor configuration  Design 4-Multiple reactions  Design 5-Energy balance on multiple reactions  Final Design-Optimization

 A total of two weeks each year are allotted for scheduled shutdowns  All reactants and products are vapors  Air is used as an oxygen source  A 1:11 ratio of propylene:oxygen is outside the flammability limits 4  The inlet pressure is 1 atm 5  Negligible kinetic and potential energy losses  Isothermal, T= K 5

Species Feed Rate to Reactor (kgmol/s) Change in Reactor (kgmol/s) Effluent Rate (kgmol/s) Propylene, C 3 H Oxygen, O Nitrogen, N Acrolein, C 3 H 4 O Water, H 2 O (v) Total Material balance for annual production rate of 75,000 metric tons *Design specification for acrolein production rate is kmol/s CH 2 =CH-CH 3 + O 2  CH 2 =CH-CHO + H 2 O

 All Design 1 assumptions  A conversion of 0.85 will be achieved 3  1000 kg/m 3 is Catalyst bulk density 6  Reactor is at steady state  Ideal gas law applies  Simple kinetics 6

 To simulate the FBR being designed, a Polymath ® model was developed.  The Polymath ® reactor was created as a function of catalyst weight  Aspen Plus ® used to examine the relationships between temperature, reactor volume, and conversion

 Developed an isothermal reactor model as function of catalyst weight using Polymath ® and ASPEN ® * Higher temperatures require smaller reactors for same conversion V = 167,000 m 3

 All Design 2 assumptions – Inlet pressure is 3 atm 6  Catalyst void fraction of  Particle diameter of 5 mm 7  Inlet viscosity is that of pure steam 4  Schedule 40 pipe used for multi-tube reactors 8

 Implemented Ergun pressure drop equation into design  Optimized reactor so pressure drop is less than 10%

V = 8,643 m 3

* Pressure drop decreases conversion

 Reactions are carried out in a catalytic FBR with temperatures ranging between °C  Acrolein is desired product  Major by-products 9 ◦ Water ◦ CO and CO 2 ◦ Acetadehyde C 3 H 6 + O 2  C 2 H 4 O + H 2 O

SymbolSpecies Chemical Formula APropyleneC3H6C3H6 BOxygenO2O2 CAcroleinC3H4OC3H4O DWaterH2OH2O ECarbon OxidesCO x FAcetaldehydeC2H4OC2H4O GNitrogenN2N2 H Carbon Dioxide CO 2 I Carbon Monoxide CO

 All Design 3 assumptions – 2830 kg/m 3 is catalyst particle density 10  Tan et al. reaction kinetics representative 9  CO 2 reaction rate independent of temperature

 Modified the reactor to include multiple reactions  Used approved reaction kinetics to calculate species flow rates V = m 3

Temperature (K) Acrolein Outlet Flow (kmol/s) Carbon Oxides and Acetaldehyde Total Outlet Flow (kmol/s) Acrolein Selectivity *Selectivity of acrolein increases with temperature

 All Design 4 assumptions  227 W/m 2 -K is heat transfer coefficient 6  Heat capacities are constant  Heats of reactions are constant  Coolant temperature is constant at K 6

An energy balance across the reactor was introduced to further validate the model as a suitable representation of the actual reactor

 Incorporated energy balance into reactor design  Compared isothermal reactor and reactor with constant coolant temperature The Effect of Coolant Temperature on Temperature Profile * Coolant temperature effects severity of hotspot V = m 3

 “Gain” measures the dynamic stability of the reactor  A “Gain”< 2 is desired Coolant Temperature (K) Polymath® Model Hotspot Temperature (K) Aspen Plus® Model Hotspot Temperature (K) GAIN

 The catalyst void fraction is  Catalyst bulk density is 1698 kg/m 3 for α-Bi 2 Mo 3 O  The inlet pressure is 3 atm 6  The inlet temperature is K 9  The coolant temperature is constant at K 6

SpecificationValue Feed Conditions Temperature K Pressure3 atm Propylene:Oxygen Ratio1:11 Propylene Conversion85% Catalyst Bed Voidage40% Particle Diameter5 mm Bulk Density1698 kg/m 3 Bed Weight kg Bed Volume m 3 Reactor Length2.40 m Overall Reactor Diameter7.60 m Tube Diameter m Number of Tubes86,304 Heat Transfer Coefficient227 W/m 2 -K Coolant Temperature K Pressure Drop9.54%

SpeciesAnnual Production (Metric Tons) Propylene, C 3 H 6 12,363 Oxygen, O 2 613,288 Nitrogen, N 2 2,269,470 Acrolein, C 3 H 4 O75,008 Water, H 2 O36,226 Acetaldehyde, C 2 H 4 O6,783 Carbon Dioxide, CO 2 25,779 Carbon Monoxide, CO2,421

 1 John J. McKetta. “Acrolein and Derivatives” Encyclopedia of Chemical Processing and Design.  2 Toxicological Profile for Acrolein, U.S. Department of Health and Human Service, Agency for Toxic Substance and Disease Registry (August 2007).  3 “Acrylic Acid and Derivatives.” Kirk-Othmer Encyclopedia of Chemical Technology. 4 th Edition.  4 Chemical Database Property Constants. DIPPR Database [Online]. Available from Rowan Hall 3 rd Floor Computer Lab. (Accessed on 1/26/08).  5 L. D. Krenzke and G. W. Keulks, The Catalytic Oxidation of Propylene: VIII. An Investigation of the Kinetics over Bi 2 Mo 3 O 12, Bi 2 MoO 6, and Bi 3 FeMo 2 O 12. The Journal of Catalysis Volume 64 (1980) p  6 Dr. Concetta LaMarca  7 “Reaction Technology.” Kirk-Othmer Encyclopedia of Chemical Technology. 4 th Edition.  8 Perry, Robert. Perry's Chemical Engineers' Handbook. 7th. New York: McGraw-Hill,  9 H.S. Tan, J. Downie, and D.W. Bacon, The Reaction Network for the Oxidation of Propylene Over a Bismuth Molybdate Catalyst, The Canadian Journal of Chemical Engineering Volume 67 (1989) p  10 Cerac Incorporated. “MSDS Search” 25 March Accessed: 8 April 2008.