Saponification of Ethyl acetate by Sodium hydroxide in a Plug Flow Reactor Lindsey Kato Shawna Togioka Luke Sugie February 2, 2005 Overview Project Objectives Project Planning and Execution Background and Experimental Methods Results and Conclusions Recommendations and Future Work Project Objectives Develop reaction kinetic data for the saponification of ethyl acetate by sodium hydroxide. 1. Develop calibration curves for electric conductivity cell, using known concentrations of reactants and products 2. Calibration of pump settings on Plug Flow Reactor (PFR). 3. Ran Batch Reactor and PFR and gathered kinetic rate data Project Planning Roles & Responsibilities Team Leader – Lindsey Kato • Planning agenda, Assigning tasks and goals, presentation Operations Coordinator – Shawna Togioka • Knowledge of equipment, data collections and laboratory documentation Safety Coordinator – Luke Sugie • Hazards of the Lab, chemical safety, MSDS Group: Background data collection and analysis Key Planning Elements 1. Project Plan / Time Table 2. Learn about the lab, equipment, safety, hazards 3. Calibration Tests 4. Batch Reactor Tests 5. PFR Tests 6. Analysis 7. Oral Presentation 8. Written Reports Lessons Learned Some activities take longer than expected Experiments don’t always run smoothly. Must rethink the experimental design. Overall – Lab time was utilized and original project plan didn’t need to be altered. Background Information Reaction: Ethyl acetate+Sodium Hydroxide → Sodium acetate+Ethanol C2H5O2CCH3 + Na-OH → CH3CO2Na + H3C-CH2-OH Theory: -rOH = -dCOH/dt = -dCEt-O-Ac/dt = k*COH*CEt-O-Ac A second order bimolecular reaction. Literature Value1,2: kOH = 0.111 L/mole-sec at 25°C Irreversible reaction Equipment Conductivity Meter Uses: measured the conductivity in the batch reactions and PFR experiments Preparation: calibrated at beginning of every lab period. Calibration curves were constructed with different concentrations of reactants and products. Equipment Constant Water Bath -Batch Reaction experiments done at 25°C -Reactants were submerged in the bath to reach temp. and then put together for the experiment. Equipment Plug Flow Reactor -Packed with small spherical balls -Bed Void Fraction3, ε, of ~0.41 -Equimolar concentrations of NaOH and Ethyl Acetate were pumped into PFR -Conductivity meter used to determine the composition of the product stream. -Experiment finished once reaction reached equilibrium. Experiments 1. Testing was done on the PFR pumps to determine the resonance time for each pump at different settings. 2. Calibration curves were generated for the conductivity meter for known concentrations of reactants and products. 3. Batch reactions were done using equimolar concentrations of reactants. 4. PFR experiments were done using equimolar concentrations and approx. equal molar flows. Batch Reactor Experiments • Bath was set to 25°C • Reactants were measured and put in bath separately to heat. • Combined reactants and conductivity measurements taken at 5 and 10 second intervals. • Batches were constantly stirred for the duration of the experiment. PFR Experiments • Large quantities of equimolar mixture of Ethyl acetate and NaOH were prepared and placed at the inlet for each pump. • The pumps were set so that the flow rates of each of the reactants would be equal. • Conductivity Meter was connected to the PFR at the outlet and readings were taken during the experiment. • Experiment was finished once the conductivity reached a steady state. Key Equations Batch Reactor COH=CEt-O-Ac Relationship: 1 = k*t + 1 COH COHo PFR COH=CEt-O-Ac Relationship: 1 * XOH = k*τ τ = V/vo (Space-time) COH 1- XOH Results – Conductivity Calibration Measurements were taken with pure NaOH, 50-50% concentration NaOH and Sodium acetate, and pure sodium acetate. 16000 y = 106167x + 7070 14000 R2 = 1 12000 10000 8000 6000 4000 2000 0 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 Results – Batch Reactor The kinetic rate constant is the initial slope at the start of the experiment. Batch Reactor Trial 5 1400 1200 1000 1/C OH 800 600 400 200 0 0 100 200 300 400 Tim e (s) Results – Batch Reactor Batch Reactor Trial 6 y = 0.1975x 15.436 y = 0.2136x ++ 16.045 Batch Reactor Trial 5 R2 = 0.9909 R2 = 0.9823 50 40 45 35 40 30 35 30 25 1/C OH 1/C OH 25 20 20 15 15 10 10 5 5 0 0 0 0 20 50 40 60 100 80 100 150 120 Tim ee(s) Tim (s) Results - PFR The flow rate of the pumps was varied to five different settings for data collection. y = 0.2431x Rlug Flow Reactor Trials R2 = 0.6406 23 22 21 20 X OH /(C OHo *(1-X OH )) 19 18 17 16 15 14 13 12 60 65 70 75 80 85 90 V/Vo (s) Results – Batch and Plug Flow Reactor • Batch Reactor showed a kinetic rate constant of ~0.19 L/mole-sec • Tests showed the rate constant to be 2 times higher than literary value, but was consistent for all trials. • Plug Flow Reactor showed the kinetic rate constant to be ~0.24L/mole-sec • The experimental value was 2.5 times higher than the literary value. Major Conclusions 1. The kinetic rate constant for batch is 0.19 L/mole- sec 2. The kinetic rate constant for a PFR is 0.24 L/mole- sec. 3. The literary value was 0.111 L/mole-sec 4. Discrepancies in the experiment and literature could be caused from slightly unequal concentrations, incorrect molar flow rates, or conductivity calibration problems. 5. Reaction data showed characteristics of being second order as theory predicted. Lessons Learned Some activities take longer than expected Experiments don’t always run smoothly. Must rethink the experimental design. Overall – Lab time was utilized and original project plan didn’t need to be altered. Future Recommendations • More careful research done early on, so work in the lab could go more smoothly. • Run more trials on the PFR and batch to confirm data. • Plan out your lab times carefully and set reasonable goals and be safe. References 1. Bamford, C.H. and C.F.H. Tipper. 1970. Comprehensive Chemical Kinetics v.10. Elsevier Publishing Company. New York. p.169. 2. Batch Reactor Kinetic Analysis. Jan 15, 2005. www.csupomona.edu/~tknguyen/che435/Notes/P5 -kinetic.pdf 3. Levenspiel, Octave. 1998. Engineering Flow and Heat Exchange. Plenum Press. New York. p.128. Questions?
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