TABLE OF CONTENT
No
Title
1
Abstract/Summary
2
2
Introduction
3
3
Aims/Objective
6
4
Theory
7-11
5
Apparatus
12-13
6
Methodology/Procedure
14-16
7
Results
17-20
8
Calculations
21-23
9
Discussion
24-26
10
Conclusion
27
11
Recommendations
28
12
Reference
29
13
Appendix
30
1|Page
Pages
1.0 ABSTRACT First of all, the equipment is set up before started the experiment by using a unit called SOLTEQ Plug Flow Reactor (Model: BP 101), commonly known as PFR, as well as some common laboratory apparatus for titration process. From this experiment, our objectives are to carry out the saponification reaction between NaOH and Et(Ac) in plug flow reactor, to determine the reaction rate constant and the rate of reaction of the saponification process. Besides that to determine the effect of residence time to the reaction's extent of conversion and lastly to evaluate the reaction rate constant of this particular saponification reaction. From the experiment, reaction between two solutions Sodium Hydroxide (NaOH) and Ethyl Acetate, Et (Ac) were reacted in the PFR. Then, the product is then analyzed by the method of titration to determine how well did the reaction go. Thus, the reason experiment was conducted also to determined results shows that the amount of conversion of Sodium Hydroxide, NaOH is almost unchanged as residence time increases. After collecting the data, the value of reaction rate constant and rate of reaction is calculated. Then, a graph of conversion factor against residence time is plotted. From the graph we can see that the conversion factor is directly proportional to the residence time. As the residence time increases, the conversion factor also increases. Further details can be obtained in the results and discussion sections. .
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2.0 INTRODUCTION A plug flow reactor is a pipe-shaped tank where a chemical reaction takes place with walls coated with a catalyst and an inlet flow of pure reactant. It consists of a cylindrical pipe and is normally operated at steady state, as is the CSTR A simple illustration for what a typical plug flow reactor is:-
Inlet Flow
outlet Flow
Figure 1 :- A simple schematic diagram for a plug flow reactor. A reactant is inserted into tank via inlet flow, after that the reactant is converted into product then flow out the reactor by the outlet flow. In generally, reactors are used in the mostly chemical industry for a million of processes to produce product. There are various different types of reactors due to the numerous different factors that can control the formation of product during the reaction. Plug flow reactors are an idealized scenario where there is no mixing involved in the reactor. It is the opposite of the continuous-stirred tank reactor (CSTR), where the reaction mixture is perfectly mixed. It is impossible to have no mixing at all during a reaction, but the amount of mixing in the reactor can be minimized. There are several advantages to minimizing the amount of mixing so that the reactor closely resembles a Plug Flow Reactor. The plug flow reactor has an inlet flow composed of the reactants. The reactant flows into the reactor and is then converted into the product by a certain chemical reaction. The product flows out of the reactor through the outlet flow. An overview of the reactor can be seen in Figure 1. A schematic of industrial tubular reactors are shown in figure below:
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Figure 2: Tubular reactor schematic. Longitudal flow reactor. Excerpeted by special permission from Chem. Eng., 63(10), 211(Oct.1956). Copyright 1956 by McGraw-Hill, Inc., New York Before the reactants are continually flow inside the Plug flow reactor, there are must have a specific assumptions are made about the extent of mixing. The validity of the assumptions will depend on the geometry of the reactor and the flow conditions-: 1. Complete mixing in the radial direction 2. No mixing in the axial direction, i.e., the direction of flow 3. A uniform velocity profile across the radius. 4. Mixing in longitudinal direction due to vortices and turbulence 5. Incomplete mixing in radial direction in laminar flow conditions In the chemical industry, plug flow reactors are frequently used due to the non-mixing property of the reactors. This is because it would be more advantageous than a mixed reactor such as a CSTR. Plug flow reactors are frequently used in biological reactions when the substrate flows into the reactor and is converted to product with the use of an enzyme. Since plug flow reactors have an inlet and outlet stream, they are useful for continuous production. The streams are opposite of a batch reactor, which is a reactor that has a constant volume and has no incoming or outgoing streams. Flow of plug flow reactor is laminar, as with viscous 4|Page
fluids in small-diameter tubes, and greatly deviate from ideal plug-flow behaviour, or turbulent, as with gases. One Plug flow reactor is an ideal tubular reactor with laminar flow behavior. Turbulent flow generally is preferred to laminar flow, because mixing and heat transfer are improved. In this experiment, the Plug Flow Reactor (Model: BP101) is used as it has been properly designed for students' experiment on chemical reactions in liquid phase under isothermal and adiabatic conditions. Included in the unit is a jacketed plug flow reactor; individual reactant feed tanks and pumps, temperature sensors and conductivity measuring sensor. By using this particular unit, students will be capable to conduct the typical saponification reaction between ethyl acetate and sodium hydroxide among the others reaction. Basically, for chemical reactions, it is impossible to proceed to 100% completion. This is because due to the rate of reaction decreases when percent completion gradually increases until the point where the system achieve dynamic equilibrium (no net reaction occurs). In fact, the equilibrium point mostly is less than 100% complete. Thus, distillation is used as a separation process, in order to separate any remaining reagents or by products from the desired product. Sometimes the reagents may be reused at the beginning of the process as a recycle back, such as in the Haber process. For application plug flow reactors are usually which are: 1. High temperature reactions 2. Continuous production 3. Homogeneous or heterogeneous reactions 4. Fast reactions 5. Large scale reactions
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3.0 OBJECTIVES The objectives of this experiment are: 1. To carry out the saponification reaction between NaOH and Et(Ac) in tubular flow reactor. 2. To determine the reaction rate constant. 3. To determine the effect of residence time on the conversion in the tubular flow reactor.
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4.0 THEORY In this theory, we used Sodium Hydroxide and Ethyl Acetate to produce Sodium Acetate and Ethyl Alcohol. The feed of reactor enters at one end of a cylindrical tube and the product stream leaves at the other end. The function plug flow reactor which is long tube and the lack of provision for stirring prevent complete mixing of the fluid in the tube. Rate of reaction can be roughly defined as the rate of disappearance of reactants or the rate of formation of products. When a chemical reaction is said to occur, a reactant will diminishes and a product will produced. That product is Sodium Acetate and Ethyl Alcohol. For example: aA+Bb cC+Dd where A and B shown that reactants meanwhile C and D represent products. In this reaction, A and B is being diminished and C and D is will be produced. Rate of reaction, concerns itself with how fast the reactants diminish or how fast the product is formed. Rate of reaction of each species corresponds respectively to their stoichiometric coefficient. For instance
-
=-
=
=
The negative sign indicates reactants mean while positive indicate product. NaOH + CH3COOC2H5 → CH3COONa + C2H5OH Sodium Hydroxide + Ethyl Acetate → Sodium Acetate + Ethyl Alcohol
4.2 Conversion Consider the general equation
aA + bB → cC + dD We choose species A as the basis of calculation, hence the reaction expression can be arranged as follows:
A+ 7|Page
B+
+
D
The basis of calculation is most always the limiting reactant. The conversion of species A in a reaction is equal to the number of moles of A reacted per mole A feed .
XA= Conversion is an improved way of quantifying exactly how far has the reaction moved, or how many moles of products are formed for every mole of A has consumed. Conversion XA is the number of moles of A that have reacted per mole of A fed to the system. Thus, irreversible reaction is the maximum values of conversion, X is that for complete conversion is X=1.0 .Meanwhile for reversible reactions where the maximum value of conversion, X is the equilibrium conversion is X=Xe.
4.3 Plug Flow Reactors It consists of a cylindrical pipe and is usually operated at steady state. For analytical purposes, the flow in the system is considered to be highly turbulent and may be modeled by that of a plug flow. Therefore, there is no radial variation in concentration along the pipe. In a plug flow reactor, the feed enters at one end of a cylindrical tube and the product stream leaves at the other end. The long tube and the lack of provision for stirring prevent complete mixing of the fluid in the tube. Hence the properties of the flowing stream will vary from one point to another. Assumptions are made regarding the extent of mixing, no mixing in the axial direction, and complete mixing in the radial direction. a uniform velocity profile across the radius.
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Mass Balance In a plug flow reactor, reactants are fed to the reactor at the inlet and the products are removed from the reactor at the outlet. The reaction takes places within the reactors as the reacting mixtures moves through the pipe. In an ideal plug of reactor, the reacting mixture is assumed to move as a plug and its properties are assumed to be uniformly distributed across the cross section of the reactor.
Differential volume dV FAf
FAo FA
FA+ dFaA
Vo
Vf
FA is the molar flow rate of A in moles per time FAo is the molar flow rate of A at the inlet in moles per time FAf is the molar flow rate of A at the exit in moles per time vo is the volumetric flow rate at the inlet in volume per time vf is the volumetric flow rate at the exit in volume per time Design equation for reactant A in the PFR is obtained by writing the mass balance for reactant A over a deferential volume of the reacting mixture dV as follows:
mass of A entering the volume dV per unit time = mass of A leaving the volume dV per unit time + mass of A accumulated within the volume dV per unit time + mass of A disappearing by the reaction within the volume dV per unit time
At steady state, no accumulation takes place. Therefore, at steady state, the above reduces to FAMA = (FA + dFA)MA + (-rA)MA dV
(Eq 4.1)
where FA is the number of moles of A per unit time entering the differential volume dV , (FA+dFA) is the number of moles of A per unit time leaving the deferential volume dV , MA is the molar mass of A, and (-rA) is the molar rate at which A is disappearing because of the progression of the reaction. Note that the unit of rA is, in general, moles per volume per time and therefore rA is multiplied by the molar mass of A to get the reaction rate in compatible unit for the mass balance given by (Eq 4.1) 9|Page
Removing MA from ( Eq 4.1) and rearranging it, we get the design equation for reactant A in an ideal PFR operated at steady-state as follows:
= rA
(Eq 4.2)
Working out in terms of the molar flow rate of A, FA: The volume VPFR required to reducing the molar flow rate of A in the PFR from FAo mol/sec at the entrance of the reactor to FAf mol/sec at the exit of the reactor can be evaluated by integrating (4.2) as follows:
VPFR =∫
d FA = ∫
(Eq 4.3)
Where (-rA) should be expressed as a function of FA. Working out in terms of the concentration of A, CA: Concentration CA in an ideal PFR is defined as follows:
CA=
=
(Eq4.4)
Equation (4.4) gives FA = CA v. Substituting which in (4.2), we get
= rA
(Eq4.5)
If the volumetric flow rate v is a constant then (4.5) yield
VPFR = ∫
=∫
d CA
(Eq4.6)
Where CAo and CAf are the respective concentrations of A at the entrance and at the exit of the reactor, respectively, and (-r A) should be expressed as a function of CA. If the volumetric flow rate v is not a constant then the solution procedure gets slightly more complicated which will be discussed in Example 4.3 of this note set.
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Working out in terms of the conversion of A, xA: Conversion of A in a PFR is defined by
XA=
–
(Eq4.7)
Which gives FA = FAo (1 – xA). Substituting which in (Eq 4.2), we get (Eq4.8) Equation (4.8), when integrated with the conditions xA = 0 at the entrance (where V = 0) and xA= xAf at the exit (where V = VPFR), gives
VPFR=∫
dxA
(Eq4.9)
where xAf is the conversion of A at the exit of the reactor, and (- rA) should be expressed as a function of xA.
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5.0 APPARATUS The unit used in this experiment is SOLTEQ Plug Flow Reactor (Model: BP101)
Figure 6.1 SOLTEQ Plug Flow Reactor (Model: BP101) Plug Flow Reactor (Model: BP101) is used as it has been properly designed for students' experiment on chemical reactions. Included in the unit is a jacketed plug flow reactor; individual reactant feed tanks and pumps, temperature sensors and conductivity measuring sensor. The apparatus in this experiment is:1. conical flask 2. measuring cylinder 3. ph. indicator 4. beakers 5. burette 6. Retort stand 7. stop watch 8. Plug Flow Reactor (Model: BP101) 9. droplet 12 | P a g e
Among the chemicals used are: 1. 0.1 M Sodium Hydroxide, NaOH 2. 0.1 M Ethyl Acetate, Et(Ac) 3. 0.1 M Hydrochloric Acid, HCl 4. De-ionised water
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6.0 Procedure OPERATING PROCEDURES General Start-Up Procedures for Experiments 3 & 4 1) Make sure that all valves are initially closed except valves V4, V8 and V17. 2) The solutions were prepared by following:a. 20 liter of sodium hydroxide, NaOH (0.1 M) b. 20 liter of ethyl acetate, Et(Ac) (0.1 M) c. 1 liter of hydrochloric acid, HCl (0.25 M), for quenching 3) The feed tank B1 was filled the NaOH solution and follow by tank B2 with the Et(Ac) solution. 4) The water jacket B4 was filled and pre-heater B5 with clean water. 5) The power for the control panel was turn on. 6) Open valves V2, V4, V6, V8, V9 and V11. 7) The both pumps P1 and P2 were switch on. The P1 and P2 were adjusted to obtain flow of approximately 300 ml/min at both flow meters FI-01 and FI-02. Make sure both flow rates are the same. 8) The both solutions were allowed to flow through the reactor R1 and overflow into the waste tank B3. 9) The valves V13 and V18 were opened. The pump P3 was switched on to circulate the water through pre-heater B5. The stirrer motor M1 was switched on and the speed was set to around 200 rpm to ensure homogeneous water jacket temperature. 10) The unit was now ready for experiment.
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General Shut-Down Procedures 1) The both pumps P1, P2 and P3 switched off. The valves V2 and V6 were closed. 2) The heaters were switched. 3) The cooling water was keep to circulating through the reactor while the stirrer motor is running to allow the water jacket to cool down to room temperature. 4) If the equipment was not going to be used for long period of time, drain all liquid from the unit by opening valves V1 to V19. Rinse the feed tanks with clean water. 5) The power for the control panel was turned off. A. Preparation of Calibration Curve for Conversion vs. Conductivity PROCEDURES:
1. The following solutions were prepared: a) 1 liter of sodium hydroxide, NaOH (0.1 M) b) 1 liter of sodium acetate, Na(Ac) (0.1 M) c) 1 liter of deionised water, H2O 2. The conductivity and NaOH concentration were determined for each conversion values by mixing the following solutions into 100 ml of deionised water: a) 0% conversion: 100 ml NaOH b) 25% conversion: 75 ml NaOH + 25 ml Na(Ac) c) 50% conversion: 50 ml NaOH + 50 ml Na(Ac) d) 75% conversion: 25 ml NaOH + 75 ml Na(Ac) e) 100% conversion: 100 ml Na(Ac)
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B. Back Titration Procedures for Manual Conversion Determination PROCEDURES: 1. A burette with 0.1 M NaOH solution was filed up. 2. 10 ml of 0.25 M HCl in a flask was measured. 3. A 50 ml sample was obtained from the experiment and immediately added the sample to the HCl in the flask to quench the saponification reaction. 4. A few drops of pH indicator were added into the mixture. 5. The mixture with NaOH solution was titrated from the burette until the mixture is neutralized. The amount of NaOH titrated was recorded.
EXPERIMENT 3: Effect of Residence Time on the Reaction PROCEDURES: 1) The general start-up procedures as in Section 4.2 were performed. 2) Valves V9 and V11 were opened. 3) The both NaOH and Et(Ac) solutions was allowed to enter the plug reactor R1 and empty into the waste tank B3. 4) The P1 and P2 were adjusted to give a constant flow rate of about 300 ml/min at flow meters FI-01 and FI-02.Make sure the both flow rates was same and recorded the data. 5) The inlet (QI-01) and outlet (QI-02) conductivity values were monitored until they do not change over time to ensure that the reactor has reached steady state. 6) The both inlet and outlet steady state conductivity values were recorded. The concentration of NaOH exiting the reactor was find and extent of conversion from the calibration curve. 7) Optional: Open sampling valve V15 and collect a 50 ml sample. A back titration procedure was carrying out to manually determine the concentration of NaOH in the reactor and extent of conversion (Section B). 8) The experiment (steps 4 to 7) was repeated for different residence times by reducing the feed flow rates of NaOH and Et(Ac) to about 250, 200, 150, 100 and 50 ml/min. Make sure that both flow rates are the same.
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7.0 RESULT Experiment 1 APPENDIX A CONVERSION
SOLUTION
CONCENTRATION CONDUCTIVITY
MIXTURE O.1 M
OF NaOH (M)
(MS)
0.1 Na(Ac)
NaOH 0%
100ml
-
100ml
0.0500
7.22ms
25%
75ml
25ml
100ml
0.0375
6.45ms
50%
50ml
50ml
100ml
0.0250
4.81ms
75%
25ml
75ml
100ml
0.0125
3.51ms
100%
-
100ml
100ml
0.0000
2.63ms
TABLE 7.1
Conductivity vs Conversion 8
Conductivity (mS/cm)
7 6 5 Conductivity vs Conversion
4 3
Linear (Conductivity vs Conversion)
y = -4.848x + 7.348 R² = 0.9875
2 1 0 0%
20%
40%
60%
80%
100%
120%
Conversion (%)
Figure 7.2 :- The graph plotted show that the conductivity versus conversion.
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Experiment 2 APPENDIX C Reactor Volume.
:4L
Concentration of NaOH in the reactor, CNaOH
: 0.1M (2L)
Concentration of NaOH in the feed vessel, CNaOH,f
: 0.1M (2L)
Concentration of HCl quench, CHCl,s
: 0.25 M (0.01L)
Volume of sample, Vs
: 0.05L
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N
FLOWRATE
FLOWRATE
TOTAL
RESIDENCE
VOLUME
O
OF NaOH
OF Et(Ac)
FLOWRATE
TIME , T
OF NaOH
(ml/min)
(ml/min)
OF
(min)
OUTLET CONDUCTIVITY (ms/cm)
CONVERSIO
REACTION
RATE OF
N x (%)
RATE
REACTION
CONSTANT
(mol/L.min)
SOLUTION,
(L/mol.min)
Q1
Q2
1.
300
300
600
6.6667
0.3
5.2
4.6
50.6
1.5365
3.7496 x 10-3
2.
250
250
500
8.0000
0.2
4.0
3.6
50.4
1.2701
3.1246 x 10-3
3.
200
200
400
10.0000
0.1
3.0
2.6
50.2
1.0080
2.4999 x 10-3
4.
150
150
300
13.3333
0.3
1.6
1.6
50.2
0.7560
1.8749 x 10-3
5.
100
100
200
20.0000
0.2
1.2
1.2
50.4
0.5081
1.2500 x 10-3
6.
50
50
100
40.0000
0.2
0.8
0.8
50.4
0.2540
6.2488 x 10-4
TABLE 7.3
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CONVERSION VS RESIDENCE TIME 50.65 50.6
50.6
50.55 CONVERSION
50.5 50.45 50.4
50.4
50.4
50.4 Residence Time Vs Conversion
50.35 50.3 50.25 50.2
50.250.2
50.15 0
10
20
30
40
50
RESIDENCE TIME,min
Figure 7.4 :- The graph plotted show that the conversion versus residence time.
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8.0 SAMPLE OF CALCULATIONS Residence Time For flow rates of 300 ml/min : Residence Time, Total flow rate, Vo
(
)
= Flow rate of NaOH + Flow rate of Et(Ac) = 300 mL/min NaOH + 300 mL/min Et(Ac) = 600 mL/min = 0.6 L/min
Hence, Residence Time,
= 6.6667 min
placed in Table 7.3
Other residence times were calculated by the same way, and varying the flow rates.
Conversion For flow rates of 300 ml/min : Moles of reacted NaOH, n1, n1= Concentration NaOH x Volume of NaOH titrated = 0.1 M x 0.0003 L = 0.00003 mole
Moles of unreacted HCl, n2, Moles of unreacted HCl = Moles of reacted NaOH n2 = n1 n2 = 0.00003 mole 21 | P a g e
Volume of unreacted HCl, V1, V1
= = = 0.00012 L
Volume of HCl reacted, V2, V2
= Total volume HCl – V1 = 0.01 – 0.00012 = 0.00988 L
Moles of reacted HCl, n3, n3
= Concentration HCl x V2 = 0.25 x 0.00988 = 0.00247 mole
Moles of unreacted NaOH, n4, n4
= n3 = 0.00247 mole
Concentration of unreacted NaOH, CNaOH unreacted
= = = 0.0494 M
Xunreacted = = = 0.494 Xreacted = 1 - Xunreacted = 1 - 0.494 22 | P a g e
= 0.506 Conversion for flow rate 300mL/min
0.506 x 100% = 50.6 %
placed in Table 7.3
Hence, at flow rate 300mL/min of NaOH in the reactor, about 50.6% of NaOH is reacted with Et(Ac). Other conversions were calculated by the same way, and varying the flow rates. Reaction Rate Constant,k (
)
For flow rates of 300 ml/min : V0
= Total inlet flow rate = 0.6 L/min
VTFR
= Volume for reactor =4L
CAO
= inlet concentration of NaOH = 0.1 M
X
= 0.506 (
) = 1.5365L.mol/min
placed in Table 7.3
Other Reaction Rate Constants were calculated by the same way, and varying the flow rates. Rate of Reaction, -rA -rA = k (CA0)2 (1-X)2 For flow rates of 300 ml/min : -rA
= 1.5365 (0.1)2 (1-0.506)2 = 3.7496 x 10-3 mol.L/min
placed in Table 7.3
Other Rate of Reactions were calculated by the same way, and varying the flow rates.
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9.0 DISCUSSION In this discussion, we are able to carry our saponification reaction between NaOH and Et(Ac) in plug flow reactor. These two solutions react together in the PFR to complete saponification reaction. The main objective of this particular experiment is to study the effect of residence time on the performance of this reactor, the PFR. Plug Flow Reactor (PFR) is a type of reactor that consists of a cylindrical pipe and is usually operated at steady state. The feed enter at one end of a cylindrical tube and leaves product from the end of cylindrical tube. The long tube and the lack of provision for stirring prevent complete mixing of the fluid in the tube. At the end of the experiment, we are able to determine the reaction rate constant by using formula and to determine the effect of residence time on the conversion in the plug flow reactor. The experiment is started by running up the equipment in order to start the saponification process. There are two method where to done the experiment saponification process which is variation in temperature or variation in contact time. In this experiment we will let the flow rate of both solutions as the varying components because the flow rate of both solutions is controlled by the temperature of the reactor. At the end of the experiment, the saponification process is successfully done. Thus, after conducting experiment, the most important part is to determine the reaction rate constant and the rate of the reaction for the saponification process depends on the vary flow rate of both solution sodium hydroxide and ethyl acetate. NaOH + CH3COOC2H5 → CH3COONa + C2H5OH Sodium Hydroxide + Ethyl Acetate → Sodium Acetate + Ethyl Alcohol The reaction rate constant can be determined by applied the equations, where:-rA = k CA2(1-X)2 -rA = FAO dX/dV = voCAO dX/dV
VTFR=
(
For constant plug flow reactor volume, flow rate and initial concentrations, the reaction rate constant is calculated by formula:24 | P a g e
(
)
After, the experiment is conducted, the data consisting inlet flow rates, conductivity value and volume of NaOH used in the titration process are tabulated in Table 1 of the Result Section. A series of calculation were made based on the data tabulated that can see in Sample of Calculation section. After that, the values of residence times, conversion of the reactions, reaction rate constants and rate of reactions were determined. These values are tabulated in Table 2 of the Result section. The reaction rate constant we get for flow rate of 300 ml/min is 1.5365 L/mol.min, for flow rate of 250 mL/min reaction rate constant is 1.2701 L/mol.min , for flow rate of 200 mL/min reaction rate is 1.0080 L/mol.min, for flow rate of 150 mL/min reaction rate is 0.7560 L/mol.min , for flow rate of 100 mL/min reaction rate is 0.5081 L/mol.min and for flow rate of last which is for the 50 mL/min reaction rate constant is 0.2540 L/mol.min. From the reaction rate constant we determined, we can see that the value of reaction rate constant is decreased as the flow rate is decrease. Thus, these shows that the reaction rate constant is depend to the flow rate flow in the plug flow reactor. The rate of reaction also can be determined after we had done find the reaction rate constant. The rate of reaction we get for 300ml/min flow rate is 0.0037496 mol/L.min, for the 250mL/min the rate of reaction is 0.0031246mol/L.min, for the 200mL/min the rate of reaction is 0.0024999mol/L.min, for the 150mL/min the rate of reaction is 0.0018749mol/L.min, for the 100 mL/min the rate of reaction is 0.0012500mol/L.min and for the 50mL/min the rate of reaction is 0.00062488mol/L.min. After all value of rate of reactions has been calculated, a graph of conversion factor against residence time is plotted. We used this formula to determine residence which is use for a function of total flow rates of the feed by time before plotting the graph, Residence Time,
(
)
From the graph that had been plotted, we can say that the conversion factor is inversely proportional to the residence time at certain point then a small changes an increase of graph conversion to the residence time .
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Supposedly, the result of conversion factor is inversely proportional to the residence time. This is maybe due to the error occurred during conducted the experiment. Thus, when the residence time is increases, the conversion factor also decreases. The concentration of sodium hydroxide decreased with increasing residence time τ as seen in figures 7.4 where the slopes are negative. Figure 7.4 showed that the conversion of sodium hydroxide increased with increasing residence time. Residence time was defined as the length of time the fluid would stay in the reactor. The longer the reactants would stay in the reactor, more products would be formed. Conversion, xA is the number of moles of A that reacted per mole of A fed to the system. The conversion is defined with respect to the basis of the calculation and in this case, species A is taken as the basis of the calculation. PFR lacks a good mixing process due to PFR is designed not to stir the solution vigorously to maximize mixing process, the conversion of the reaction by using PFR is fairly low. The experiment also aims to evaluate the reaction rate constants and rate of reaction values of the reaction. Both of these properties have been determined in the result section.
.
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10.0 CONCLUSION From this experiment, we are able to carry out the saponification reaction between NaOH and Et(Ac) in plug flow reactor. The reaction between them is pass through the plug flow reactor, mixed and react at certain period of time. In plus, we are able to determine the reaction rate constant for the saponification process. The reaction rate constant we get for flow rate of 300ml/min is 1.5365 L/mol.min, for flow rate of 250 mL/min reaction rate constant is 1.2701 L/mol.min , for flow rate of 200 mL/min reaction rate is 1.0080 L/mol.min, for flow rate of 150 mL/min reaction rate is 0.7560 L/mol.min , for flow rate of 100 mL/min reaction rate is 0.5081 L/mol.min and for flow rate of last which is for the 50 mL/min reaction rate constant is 0.2540 L/mol.min. By doing that, saponification process was completed. There are many scenarios that must be considered when deciding on which type of reactor to use for a certain process. A plug flow reactor is one of many types of reactors. It is most useful when the reaction is not allowed to reach equilibrium, and the reaction is kinetically limited by the reaction rate. Besides that, from this experiment we also are able to determine the reaction rate of this particular reaction. From sample calculation done show the data get from result use for calculating to achieve our objective .Moreover, from this experiment also, we can study the relationship between the residence time and the conversion of the reactants. The graph had been plotted based on the data result after calculation and it allow to study the relationship between residence time and conversion. From the graph that had been plotted, we can say that the conversion factor is inversely proportional to the residence time. Where, when the residence time increases, the conversion factor also decreases. This experiment was a success. If compare to the CSTR , PFR does have a higher rate of product production than a CSTR if the reaction is kinetically limited.
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11.0 RECOMMENDATION There are several recommendations that can be taken in order to get more accurate result that are: 1. This experiment should be repeated at various other temperatures to investigate the relationship between the reaction rate constant and the rate of reaction. 2. It is further recommended that the experiment be repeated using dissimilar flow rates for the NaOH solution and ethyl acetate solutions to investigate the effect that this will have upon the saponification process. 3. For obtained more accurate results, run several trials on tubular flow reactor so we can take the average value from each different molar rates. 4. During titration students should more alert and carefully because we only want the last drop of NaOH that will convert the solution to light pale purple colour. Thus, the excess of drop of NaOH will give effect on the result in the calculations. 5. During conducted experiment, the flow rates should be constantly monitored to prevent any changes occur that can influence our result. 6. Titration should be immediately stopped when the indicator turned pink.
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12.0 REFERENCES
1.
Design
of
Ideal
Plug
Flow
Reactors
(PFRs)
(Retrieved
from
http://www.rshanthini.com/tmp/CP303/set4.pdf on the 17th April 2014) 2. Laboratory Manual Plug Flow Reactor. 3. The Plug Flow Reactor (Retrieved from http://www.konferenslund.se/p/L16.pdf on the 17th April 2014) 4. Reaction Kinetics (Retrieved from http://smk3ae.files.wordpress.com/2007/10/reaksi-kinetik.pdf on the 17th April 2014) 5.
Fundamentals
of
Chemical
Reactor
Theory
(Retrieved
from,
http://www.seas.ucla.edu/stenstro/Reactor.pdf on the 17th April 2014) 6. Reaction kinetic studies in a plug flow reactor Background and Theory (Retrieved from, http://solve.nitk.ac.in/dmdocuments/Chemical/theory_plugflow.pdf on the 17th April 2014)
29 | P a g e
13.0 Appendix
Figure 13.1:-SOLTEQ Plug Flow Reactor (Model: BP101)
Figure 13.2:Titration 30 | P a g e
