Chemical Reaction Engineering 40 L CSTR Saponification

FACULTY OF CHEMICAL ENGINEERINGUiTM Terengganu, Bukit Besi Campus

Program:Diploma in Chemical Engineering

Course:Introduction To Chemical Reaction Engineering

Course Code:CHE244

Lecturer:Marshahida bin Mat Yashim

Laboratory Report

Experiment TitleTHE SAPONIFICATION REACTION OF ETHYL ACETATE, ET(AC) AND SODIUM HYDROXIDE, NAOH

NoName Student ID NoSignature

1.MOHAMAD TURMIZI BIN JAAFAR2013450634

2.AMIRUL AIMAN BIN ZULFAKAR2013419606

3.MUHAMMAD AZIZI BIN AB WAHAB2013451738

4.NUR SYAFIQAH BINTI MOHD SAIDI2013884596

5.NOR SYAZA MUNIERAH BINTI SALLEH2013246812

Received by:-

________________________MARSHAHIDA BINTI MAT YASHIMDate :

Date of Experiment: 03.09.2014Date of Submission:23.09.2014

List of contentsTHE SAPONIFICATION REACTION OF ETHYL ACETATE, ET(AC) AND SODIUM HYDROXIDE, NAOH11.0INTRODUCTION52.0OBJECTIVE73.0APPARATUS84.0THEORY115.0PROCEDURE137.0DISCUSSION188.0CONCLUSION19Bibliography21

List of figuresFigure 1 : Cross-sectional diagram of Continuous stirred-tank reactor5Figure 2 : Single Continuous Stirred Tank Reactors (CSTRs)6Figure 3 : Continuously Stirrer Tank Reactor (CSTR) in series6Figure 4 : 25 mL burette8Figure 5 : Stand with clamps8Figure 6 : Conical Flask9Figure 7 : Continuous Stirred Tank Reactor 40L9Figure 8 : 100 ML Beaker10Figure 9 : Calibration curve (Conversion vs. Conductivity)16Figure 10 : Graph of conversion against residence time16

List of tablesTable 1 : Calculations for back titration12Table 2 : Preparation calibration curve15Table 3 : Effect of residence time Continuous Stirred Tank Reactor15

TITLE : THE SAPONIFICATION REACTION OF ETHYL ACETATE, ET(AC) AND SODIUM HYDROXIDE, NAOH1.0 INTRODUCTION

Firstly, a common type of reactor is the mixing, or stirred reactor .The basic components of this device will include a mixer or agitator mounted to a tank. One of the stirred reactors is Continuous Stirred Tank Reactors (CSTR). The flow stirred tank reactor in series is a common reactor type in environmental applications. The principle characteristic is that the reactor is assumed to be instantaneously and perfectly mixed. Majority of industrial chemical processes, a CSTR reactor is the equipment in which raw materials undergo a chemical change to form desired product. The types of process this equipment is the continuous stirred tank reactor which is this reactor is almost always operated at steady state. The CSTR reactor used are most commonly used in industrial processing, primarily in homogeneous liquid-phase flow reactions, where constant agitation is required. They may be used by themselves, in series, or in a battery. It is referred to as the continuously stirred tank reactor (CSTR). It is normally operated at steady state and is assumed to be perfectly mixed. The characteristic of this equipment is run at steady state with continuous flow of reactants and products, the feed assumes a uniform composition throughout the reactor, and exit stream has the same composition as in the tank.

Figure 1 : Cross-sectional diagram of Continuous stirred-tank reactor

The CSTR can run as single reactor and also in series. The CSTR reactor is connected in series so that the exit stream of onereactor is the feed stream for another reactor.There are three reactor vessels connected in series by piping, each containing a propeller agitator driven by a variable speed electric motor and the unit based on the simplest classic case of well mixed, multi-staged process operation. The solution in each reactor is well stirred and the concentration can be measured. These three reactors are to compare the measured responses of the vessel concentrations to deliberate change at the inlet with a theoretical prediction.

Figure 2 : Single Continuous Stirred Tank Reactors (CSTRs)

The piping arrangement has been designed to include a dead time coil in the system. Feed liquid to the first vessel is drawn from of the two sump tanks by a pump, via a flow meter and control valve. The trace material concentration in each sump tank is made to be different. At a selected instant, a sudden change from one feed to the other is made: either for continuous period is known as the step function, or for a short interval is known as impulse function, and the concentration or conductivity changer with time in each vessel is measured.

Figure 3 : Continuously Stirrer Tank Reactor (CSTR) in series

The advantages of CSTR are easily maintained, good temperature control, cheap to construct, reactor has large heat capacity and interior of reactor is easily accessed. Meanwhile, the disadvantages of using CSTR are lowest conversion per unit volume and also by-passing and channelling possible withpoor agitation.2.0 OBJECTIVE

That shown the objective of this experiment:i) To carry out a saponification reaction between NaOH and Et(Ac) in a CSTR.ii) To determine the effect of residence time onto the reaction extent of conversion..iii) To determine the reaction rate constant.

3.0 APPARATUS

A. SCALELIQUIDHOLDER

Figure 4 : 25 mL burette

BURETTEBASECLAMP

B.

Figure 5 : Stand with clamps

C. SCALE

Figure 6 : Conical Flask

D.

Figure 7 : Continuous Stirred Tank Reactor 40L

E. Figure 8 : 100 ML Beaker

4.0 THEORY

One of the organic chemical reactions known to ancient man was the preparation of soaps through a reaction called saponification. Natural soaps are sodium or potassium salts of fatty acids, originally made by boiling lard or other animal fat together with lye or potash (potassium hydroxide). Hydrolysis of the fats and oils occurs, yielding glycerol and crude soap. In the industrial manufacture of soap, tallow (fat from animals such as cattle and sheep) or vegetable fat is heated with sodium hydroxide. Once the saponification reaction is complete, sodium chloride is added to precipitate the soap. The water layer is drawn off the top of the mixture and the glycerol is recovered using vacuum distillation.The equation below shows the saponification process between sodium hydroxide and ethyl acetate (irreversible reaction) toproduce sodium acetate andby-product ethanol.

NaOH + C2H5O2CCH3 CH3CO2Na + H3CCH2OHSodium Hydroxide Ethyl Acetate Sodium Acetate Ethanol

A. Preparation of Calibration Curve for Conversion vs. Conductivity

The reaction to be studied is the saponification reaction of ethyl acetate Et(Ac) and sodium hydroxide (NaOH). Since this is a second order reaction, the rate of reaction depends on both concentrations of Et (Ac) and NaOH. However, for analysis purposes, the reaction will be carried out using equimolar feeds of Et (Ac) and NaOH solutions with the same initial concentrations. This ensures that both concentrations are similar throughout the reaction.

NaOH + Et(Ac) Na(Ac) + EtOH

It will calibrate the conductivity measurement of conversion values for the reaction between 0.1 M ethyl acetate and 0.1 M sodium hydroxide that we will get from the experiment.

B. Back Titration for Manual Conversion Determination

It is advisable to carry out manual conversion determination on experiment samples to verify the conductivity measurement values. It is based on the principle of quenching the sample with excess acid to stop any further reactions, then back titrating with a base to determine the amount of unreacted acid.

NaOH + HCl NaCl + H2O

The calculations of back titration :

No.QuantitiesFormulaUnit

1.Concentration of NaOH entering the reactor, CNaOH,0

CNaOH,fmol/L

2.Volume of unreacted quenching HCL, V2 (CNaOH,s/CHCL,s) x V1mL

3.Volume of HCL reacted with NaOH in sample, V3VHCL,S V2mL

4.Moles of HCL reacted with NaOH in sample, n1(CHCL,S x V3) / 1000mol

5.Moles of unreacted NaOH in sample, n2n1mol

6.Concentration of unreacted NaOH in the reactor, CNaOHn2 / Vs x 1000mol/L

7.Conversion of NaOH in the reactor, X[1 (CNaOH / CNaOH,0 )] x 100%

Table 1 : Calculations for back titration

C. Reaction Rate Constant

5.0 PROCEDURE

1. Preparation of Calibration Curve for Conversion vs. Conductivity

i) The solutions for the first method were prepared 1 L of sodium hydroxide, NaOH ( 0.1 M ) 1 L of sodium acetate, Et (Ac) ( 0.1 M ) 1 L of deionised water, H2O

ii) The conductivity and NaOH concentration had been determined for each conversion values by mixing the solutions into 100 mL of deionised water :

0% conversion :100 mL NaOH 25% conversion :75 mL NaOH + 25 mL Et (Ac) 50% conversion :50 mL NaOH + 50 mL Et (Ac) 75% conversion :25 mL NaOH + 75 mL Et (Ac) 100% conversion :100 mL Et (Ac)

2. Back Titration for Manual Conversion Determination

i) 0.1 M NaOH solution was filled in a burette.ii) 10 mL of 0.25 M HCL was measured in a flask.iii) 50 mL sample had been obtained from the experiment and had been added up to the HCL in the flask immediately to quench the saponification reaction.iv) A few drops of pH indicator were added into the mixture.v) The mixture had been titrated with NaOH solution from the burette until the mixture is neutralized and the amount of NaOH titrated was recorded.

3. Reaction Rate in the CSTR

i) The general start-up procedures as before were performed.ii) Both pumps P1 and P2 were switched on simultaneously and valves V5 and V10 were opened to obtain the highest possible flow rate into the reactor.iii) The reactor had been filled up with both the solution until it is just about to overflow.iv) The valves V5 and V10 were readjusted to give flow a rate of about 0.1 L/min. Both flow rate were made at the same value and it had been recorded.v) The stirrer M1 was switched on and the speed was set up about 200 rpm.vi) The conductivity value was started to be monitored at Ql-401 until it does not change over time. This is to ensure that the reactor has reached steady state.vii) The steady state conductivity value was recorded and the concentration of NaOH in the reactor was obtained and extent of conversion from the calibration curve.viii) Sampling valve V12 was opened and a 50 mL sample was collected. Back titration procedure was carried out to manually determine the concentration of NaOH in the reactor and extent of conversion.ix) The experiment was repeated (step 5 to 9) for different residence times by adjusting the feed flow rates of NaOH and Et (Ac) to about 0.15, 0.20, 0.25, 0.30 L/min. Both flow rates were make sure to be the same.

6.0 RESULT

ConversionSolution MixturesConcentration of NaOH (M)Conductivity (mS/cm)

0.1 M NaOH0.1 M Et(Ac)H2O

0%100 mL-100 mL0.05005.930

25%75 mL25 mL100 mL0.03752.160

50%50 mL50 mL100 mL0.02501.619

75%25 mL75 mL100 mL0.01250.757

100%-100 mL100 mL0.00000.0900

Table 2 : Preparation calibration curve

Reactor volume: 40 LConc. of NaOH in feed vessel: 0.1 MConc. of Et(Ac) in feed vessel: 0.1 M

NoTemperature (C)Flow rate of NaOH (mL/min)Flow rate of Et (Ac) (mL/min)Total flow rate of solutions, F0 (mL/min)Residence time, (min)Conductivity (mS/cm)Exit concentration of NaOH, CNaOH (M)Conversion, X (%)

1.27.0100100200200.003.300.00296

2.27.1150150300133.333.140.00492

3.27.3200200400100.003.000.00590

4.27.525025050080.002.900.00688

5.27.730030060066.672.780.00884

Table 3 : Effect of residence time Continuous Stirred Tank Reactor

Figure 9 : Calibration curve (Conversion vs. Conductivity)

Figure 10 : Graph of conversion against residence time

CALCULATION

NaOH + HCl NaCl +H2O

Sample calculations for flow rate = 0.10 L/min

Volume of sample, Vs= 50 mL

Concentration of NaOH in the feed vessel, CNaOH,f = 0.1 M

Volume of HCl for quenching, VHCl,s = 10 mL

Concentration ofHCl in standard solution, CHCl,s = 0.25 mol/L

Volume of NaOH titrated, V1= 24.0 mol/L

Concentration ofNaOH used for titration, CNaOH,s = 0.1 mol/L

Concentration of NaOH entering the reactor, CNaOH,0 = (1/2)(0.1) = 0.05 mol/L

Volume of unreacted quenching HCl, V2= (CNaOH,s/CHCl,s) x V1= (0.1/0.25) x 24.0= 9.6 mL

Volume of HCl reacted with NaOH in sample, V3= VHCl,s - V2= 109.6= 0.4 mL

Moles of HCl reacted with NaOH in sample, n1= (CHCl,sx V3)/1000= (0.25 x 0.4) /1000= 0.0001mol

Moles of unreacted NaOH in sample, n2 = n1 = 0.0001 mol

Concentration of unreacted NaOH inthe reactor, C NaOH = n2/ Vs x 1000= x1000= 0.002

Conversion of NaOH in the reactor, X = (1 - ) x 100% = (1 - ) x 100% = 92%

Residence time, = VCSTR/F0 = 40 L/ (0.10 + 0.10) L/min = 200 min7.0 DISCUSSION

The experiment is conducted to determine the reaction rate and to determine the effect of the residence time on the conversion in Plug Flow Reactor which related with it. The CSTR model is used to predict the behaviour of chemical reactors, so that the key reactor variables, which is the dimensions of the reactor, can be estimated.

The experiment is conducted by setting the flow rate of both solutions NaOH and Et(Ac) into 0.10 L/min, 0.15 L/min, 0.20 L/min, 0.25 L/min and 0.30 L/min at each run of experiment. From the experiment, the residence time is about to decrease when the flow rates of the reactor become faster. Residence time is the removal time which is the average amount of time that a particle spends in a particular system. Furthermore, residence time is measured with the amount of substance which is present in the system.

When using the residence timeequation, it is significant to made a varietyof assumptions.It is assumed that chemical degradation does not occur in the system in question and that particles do not attach to surfaces that would hinder their flow. If chemical degradation were to occur in a system, the substance that originally entered the system may react with other existing compounds in the system, causing the residence time to be significantly shorter since the substance would be chemically broken down and effectively be removed from the system before it was able to naturally flow out of the system

Therefore, when the residence time decrease, it indicates that less molecules of reactants are reacted with each other. Thus, the conversion of reactant into product is decrease. From the result, it shows that when the flow rates was set into 0.30 L/min for both reactants which is the highest flow rate in this experiment; the residence time of that reactants in the CSTR is the shortest which is 66.67 min and give out the result forconversion of 84.0%.Oppositely, when the flow rate for both reactants was set into 0.10 L/min which is the lowest flow rate, the residence time of those reactants in the CSTR is the longest which is 200 min and the highest conversion of the reactants is 96.0 %. While for flow rates of 0.15 L/min, 0.20 L/min and 0.25L/min; the residence time are 133.33 min, 100.00 min and 80.00 min respectively and the conversion of reactants are 92.0 %, 90.0 % and 88.0 % respectively.

8.0 CONCLUSION

The purpose of this experiment is to carry out saponification reaction between NaOH and Et(Ac) in a CSTR which also required to determine the effect of residence time onto the reaction extent of conversion and to determine the reaction rate constant. Continuous stirred tank reactor is used in this experiment in order to achieve the purpose of this experiment. After completing the experiment, we are able to collect the data and all the purposes are achieved. From the results, it shows that each of the flow rates increase from 0.10 L/min to 0.30 L/min, the conversion of NaOH decrease from 96% to 84%. The graph shows that conversion of NaOH versus residence time is plotted. It is directly proportional. As the conversion decrease, the residence is decrease as well.There are a few recommendations that can improve the experiment result. With these recommendations, the result would be more better than before. This experiment is considered succeed as all the purposes are achieved.

9.0 RECOMMENDATIONS

1. The device needs to be well maintenance in order to avoid it from malfunctioning during the experiment period like the one we are having in our session.

2. To get a better result, only one person is needed to take care of the opening and closing of the valve and other person take care of the pump. This is because some valve needed to be opened or closed simultaneously.

3 Make sure the tank is filled with the correct solution and to the correct amount. Different substance reacts differently and lack of substance can damage the apparatus.

4 Make sure general start-up procedure is done first in order to check the machine functionality.

5 The burette should be rinsed with sodium hydroxide after rinsed using thedistilled water.

10.0 REFERENCES

BibliographyA.James. 2014. [Online] 19 September, 2014. [Cited: 01 June, 2012.] http://en.wikipedia.org/wiki/Saponification.M.Rone. 1975. [Online] 18 July, 1975. [Cited: 7 May, 1975.] http://www.sciencedirect.com/science/article/pii/0009250976850580.Wojes, Rayan. 2014. A.Datum. [Online] 5 May, 2014. [Cited: 23 september, 2014.] http://iitkgp.vlab.co.in/?sub=35&brch=107&sim=1175&cnt=1.