1.0 ABSTRACT
This experiment is conducted in order to achieved a few aims or objectives. The experiment is to carry out a saponification reaction between NaOH and Et(Ac) in continuous stirred tan reactor or common!y nown as "#T$. The objectives for this experiment are to determine the effect of residence time onto the reaction extent of conversion and to determine the reaction of rate constant constant and !ast!y to determine the reaction%s reaction%s activation activation ener&y. ener&y. 'n order to conduct this experiment a continuous stirred tan reactor mode! *+, is used. efore we started- we ensured that a!! the &enera! start up was carried out proper!y to avoid any mistae that wi!! effect the resu!t obtained. The experiment is started by openin& va!ves / / and *0 to obtain obtain the hi&hest possib!e f!ow rates that can be achieve. Then- the readjust va!ves / and *0 to achieve 0.* 12min but both f!ow rates readin& must be the same for va!ves / and *0. This steps is repeated by different va!ue of f!ow rates which is 0.*/- 0.30- 0.3/- and 0.,0 12min. 4or each f!ow rate s/0 m1 of samp!e wi!! be co!!ected in order to carried to a bac titration. titration. The stab!e conductivity conductivity is recorded into a data for every /min before co!!ect the samp!es. samp!es. 'n the the bac bac titr titrat atio ionn- the the samp samp!e !ess that that had had been been co!! co!!ec ecte ted d are are titr titrat ated ed with with NaOH NaOH for for saponi saponifica ficatio tion n reactio reaction n unti! unti! it chan&e chan&e co!our co!our from from co!our co!our!ess !ess into into !i&ht !i&ht pin. pin. ThenThen- the amount of NaOH titrated were recorded. 4rom the tabu!ated data- a few of ca!cu!ation are carried out and &raph had been p!otted.
2.0 INTRODUCTION
One of the important component in the industria! sector that he!p the operation of the factory to produce products is a reactor. A reactor wi!! chan&e a raw product into the desire product that are needed. The ri&ht criteria for a &ood reactor is it can produce a hi&h production with a &reat 5ua!ity and economica!. economica!. A common common type of reactor reactor that usua!!y used in the industry is the mixin& or stirred reactor. One of the stirred reactors is "ontinuous #tirred Tan $eactors ("#T$) this reactor is a common idea! reactor type in chemica! en&ineerin&. 6ajority in chemica! chemica! process industry industry-- "#T$ is bein& bein& used as an e5uipment e5uipment which is raw materia!s materia!s under&o a chemica! chan&e in order to form desired product. The types of process for this e5uipment is steady state because most of the this reactor wi!! operate at steady state and it is assume to be in perfect!y mixed. The "#T$ reactor used are common!y used in industria! processin&- primari!y in homo&eneous !i5uid7phase f!ow reactions- where constant a&itation is re5uired.
4i&ure * "ross7sectiona! dia&ram of "ontinuous stirred7tan reactor As for this experiment a continuous stirred tan reactor -"#T$ (mode! 8 *+,) is bein& used. The "#T$ can run as sin&!e reactor and a!so in series. The "#T$ that connected in seriesthe exit stream of one reactor is the feed stream for another reactor. There are three reactor vesse!s connected in series by pipin&- each containin& a prope!!er a&itator driven by a variab!e speed e!ectric motor and the unit based on the simp!est c!assic case of we!! mixedmu!ti7sta&ed process operation. The so!ution in each reactor is we!! stirred and the concentration can be measured. These three reactors are to compare the measured responses of the vesse! concentrations to de!iberate chan&e at the in!et with a theoretica! prediction.
4i&ure 3 #in&!e "ontinuous #tirred Tan $eactors ("#T$)
4i&ure , "ontinuous!y #tirrer Tan $eactor ("#T$) in series.
3.0 OBJECTIVE
The objective of this experiment are 8
• • •
To carry out a saponification reaction between NaOH and Et(Ac) in a "#T$. To determine the effect of residence time onto the reaction extent of conversion To determine the reaction rate constant To determine the reaction%s activation ener&y
4.0 THEORY
#aponification is a process where a!a!ine hydro!ysis the fatty acid ester. 'n this experiment it is invo!ved hydro!y9ed of esters in fat by sodium or potassium hydroxide (NaOH or :OH) to produce a carboxy!ate anion which can act as surfactant for examp!e soap. The e5uation be!ow shows the saponification process between sodium hydroxide and ethy! to produce sodium acetate and by product ethano!.
"3H/O3""H, Ethy! Acetate
; NaOH < "H,"O3 Na ; H,""H3OH #odium Hydroxide #odium Acetate Ethano!
As for the experiment preparation of ca!ibration curve for conversion vs conductivity- the reaction that need to be studied in this experiment is the saponification reaction of ethy! acetate Et(Ac) and sodium hydroxide (NaOH). #ince this is a second order reaction- the rate of reaction depends on both concentrations of Et(Ac) and NaOH. However- for ana!ysis purposes- the reaction wi!! be carried out usin& e5uimo!ar feeds of Et (Ac) and NaOH so!utions with the same initia! concentrations. This ensures that both concentrations are simi!ar throu&hout the reaction.
NaOH ; Et (Ac)
Na(Ac) ; EtOH
4rom this experiment- it is re5uired to ca!ibrate the conductivity measurements of conversion va!ues for the reaction between 0.* 6 ethy! acetate and 0.* 6 sodium hydroxide. The conversion wi!! start from 0= conversion- 3/= conversion- /0= conversion- >/= conversion- and *00= conversion. Each of the conversion contains different amount NaOHEt(Ac)- and deionised water for examp!e for 0= conversion there wi!! be *00 m1 of NaOHfor >/= conversion wi!! contains 3/ m1 of NaOH ; >/ m1 Et(Ac)- and for *00= conversion it wi!! contain *00 m1 of Et(Ac). ?ifferent percenta&e of conversion wi!! &ive different va!ue of conductivity. 4or bac titration procedure it is advisab!e to carry out manua! conversion determination on experiment samp!es to verify the conductivity measurement va!ues. 't is based on the princip!e of 5uenchin& the samp!e with excess acid to stop any further reactions- then bac titratin& with a base to determine the amount of unreacted acid.
NaOH ; H"!
The bac titration can be ca!cu!ate as fo!!ow 8
"onc. of NaOH enterin& the reactor- (" NaOH-o)
C NaOH , f 2
o!ume of unreacted 5uenchin& H"!- ( 3)
C NaOH , s × V 1 C HCl, s
Na"! ; H3O
o!. of H"! reacted with NaOH in samp!e- ( ,)
V HCl,s V 2 −
6o!es of H"! reacted with NaOH in samp!e- (n *)
V 3
C NaOH ,s×
1000
6o!es of unreacted NaOH in samp!e- (n 3)
n2 n 1 =
"onc. of unreacted NaOH in the reactor- (" NaOH) n2 V s 1000
"onversion of NaOH in the reactor- @
(
1−
)
C NaOH × 100 C NaOH ,o
$eaction rate constant
: ("AO7 "A) 3
"A
5.0 APPARATUS
*. 3. ,. +. /.
"ontinuous stirred tan reactor (6ode! 8 *+,) /0 m1 burette 300 m1 beaer "onica! f!as #o!ution 8 i. #odium hydroxide- NaOH (0.*6) ii. #odium acetate- Et(Ac) (0.* 6) iii. ?eionised water- H3O iv. Hydroch!oric acid- H"1 (0.3/6) v. heno!phtha!ein B. "onductivity probe >. *00 m1 measurin& cy!inder.
4i&ure
6.0 PROCEDURE GENERAL START-UP PROCEDURE :
*. The fo!!owin& so!utions are prepared 8 '. +0 1 of sodium hydroxide- NaOH (0.*6) ''. +0 1 of ethy! acetate- Et(Ac) (0.*6) '''. * 1 hydroch!oric acid- H"1 (0.3/6)- for 5uenchin& 3. A!! va!ves are ensured initia!!y c!osed. ,. The feed vesse!s are char&ed as fo!!ows8 '. The char&e port caps for vesse!s * and 3 ae opened ''. NaOH so!ution is poured carefu!!y into vesse!s +. The power for the contro! pane! is turned on. /. The water in the thermostat T* tan is checed. $efi!!ed as necessary. B. "oo!in& water va!ve *, is opened and the coo!in& water is !et to f!ow throu&h the condenser C*. (on!y for experiment 3) >. The overf!ow tube is adjusted to &ive a worin& vo!ume of *0 1 in the reactor $*. D. a!ves 3- ,- >- D- and ** are opened. . The unit is now ready for experiment.
PREPARATION
OF
CALIBRATION
CURVE
FOR
CONCENTRATION
VS
CONDUCTIVITY
*. The fo!!owin& so!utions are prepared 8 '. * !iter osf sodium hydroxide- NaOH (0.*6) ''. * !iter of sodium acetate- Et(Ac) (0.*) '''. * !iter of deionised water- H3O 3. The conductivity and NaOH concentrationfor each conversion va!ues by mixin& the fo!!owin& so!utions into *00 m1 of deionised water are determined 8 '. 0= conversion 8 *00 m1 NaOH ''. 3/= conversion 8 >/ m1 NaOH ; 3/ m1 Et(Ac) '''. /0= conversion 8 /0 m1 NaOH ; /0 m1 Et(Ac) '. >/= conversion 8 3/ m1 NaOH ; >/ m1 Et(Ac) . *00= conversion 8 *00 m! Et(Ac)
BAC
TITRATION
PROCEDURES
FOR
!ANUAL
CONVERSION
DETER!INATION
*. Aburette is fi!!ed up with 0.* 6 NaOH so!ution. 3. *0 m1 of 0.3/ 6 H"! in a f!as. ,. /0 m1 samp!e is obtained from the experiment and the samp!e is immediate!y added to the H"! in the f!as to 5uench the saponification reaction. +. A few drops of pH indicator are added into the mixture. /. The mixture is titrated with NaOH so!ution from the burette unti! the mixture is neutra!i9ed. The amount of NaOH titrated is recorded.
E"PERI!ENT 1 : EFFECT OF RESIDENCE TI!E OF THE REACTION IN A CSTR.
*. The &enera! start7up procedure is performed. 3. oth pumps * and 3 are switched on simu!taneous!y and va!ves / and *0 are opened to obtain the hi&hest possib!e f!ow rate into the reactor. ,. The reactor is !et to fi!! up with both the so!ution unti! it is just about to overf!ow. +. The va!ves / and *0 are readjusted to &ive a f!ow rate of about 0.* 12min. oth f!ow rate are mae sure to be the same. The f!ow rate is recorded. /. The stirrer 6* is switched on and the speed is set to about 300 rpm. B. The conductivity va!ue at F*7+0* ia started monitorin& unti! it does not chan&e over time.The reactor is ensured had reached steady state.
>. The steady state conductivity va!ue is recorded and the concentration of NaOH in the reactor is found and extent of conversion from the ca!ibration curve. D. #amp!in& va!ve *3 is opened and /0 m1 samp!e is co!!ected. A bac titration procedure is carried out to manua!!y determine the concentration on NaOH in the reactor and extent of conversion. . The experiment are repeated from steps / to
for different residence times by
adjustin& the feed f!ow rates of NaOH and Et(Ac) to about 0.*/- 0.30- 0.3/ and 0.,0 12min. oth f!ow rates are mae sure the same.
E"PERI!ENT 2 : EFFECT OF TE!PERATURE ON THE REACTION IN A CSTR
*. The &enera! start7up procedures are performed. 3. oth pumps * and 3 are switched on simu!taneous!y and va!ves / and *0 are opened to obtain the hi&hest possib!e f!ow rate into the reactor. ,. The reactor is !et to fi!! up with both the so!ution unti! it is just about to overf!ow. +. The va!ves / and *0 is readjusted to &ive a f!ow rate of 0.30 12min. oth f!ow rates is mae sure the same. The f!ow rates are recorded. /. The stirrer 6* is switched on and the speed at about 300 rpm is set. B. The thermostat T* is switched on and the water temperature is set to +0 o". >. The conductivity va!ue at F*7+0* are started monitorin& and the temperature va!ue at T*7*0* unti! they do not chan&e over time.This is to ensure that the reactor has reached steady state. D. The steady state conductivity va!ue and temperature va!ues are recorded and the concentration of NaOH in the reactor is found and extent of conversion from the ca!ibration curve. . #amp!in& va!ves *3 is opened and /0 m1 samp!e is co!!ected. A bac titration procedure is carried out to manua!!y determine the concentration of NaOH in the reactor and extent of conversion. *0. The experiment is repeated from steps > to *0 for different reactor temperatures by settin& the thermostat temperature to /0- B0- >0- and D0 o". The f!ow rates of both so!utions are mainteained at 0.30 12min. GENERAL SHUT-DO#N PROCEDURE
*. The coo!in& water va!ve *, is ept open to a!!ow the coo!in& water to continue f!owin&. 3. oth pumps * and 3 are switched off. #tirrer 6* is switched off.
,. The thermostat T* is switched off. The !i5uid in the reaction vesse! $* is !et to coo! down to room temperature. +. "oo!in& water va!ve *, is c!osed. /. a!ves 3- ,- > and D are c!osed. a!ves +- and *3 are opened to drain any !i5uid from the unit. B. The power for the contro! pane! is turned off. $.0 RESULTS
"onversion
#o!ution mixtures 0.* 6 NaOH 0.* 6 H3O Et(Ac)
0= 3/= /0= >/= *00=
i!.
*00 m1 >/ m1 /0 m1 3/ m1 7
7 3/ m1 /0 m1 >/ m1 *00 m1
4!ow
rate
(o")
NaOH- (12min)
"onductivity
n of NaOH
(m#2cm)
(6) 0.0/00 0.0,>/ 0.03/0 0.0*3/ 0.0000
*00 m1 *00 m1 *00 m1 *00 m1 *00 m1 Tab!e *
Temperature
"oncentratio
*+.+0 D.0 +.>/0 ,.*/0 0.*3>
of 4!ow rate of Et(Ac)- Tota! f!ow rate of $esidence (12min)
so!ution-4o-(12min)
time-
(min) *. 3. ,. +. /.
3.D ,0.0 ,0.3 ,0.+ ,0./
0.*0 0.*/ 0.30 0.3/ 0.,0
0.*0 0.*/ 0.30 0.3/ 0.,0
0.30 0.,0 0.+0 0./0 0.B0
300.00 *,,.,, *00.00 D0.00 BB.B>
Tab!e 3
roperty 4ormu!a Appearance 6o!ecu!ar wei&ht Norma! boi!in& point Norma! me!tin& point ?ensity $efractive index
Ethy! acetate "H,"OO"H3"H, "!ear !i5uid DD.** &2mo! >>.* o" 7D+.0 o" 0.D+/ &2mo! G 3/ o" *.,3>+ G 30 o"
#odium hydrox NaOH Chite so!id +0.00 &2mo! *,0 o" ,3, o" 3.* &2mo! 7
Tab!e ,
%.0 CALCULATIONS
"onc. of NaOH enterin& the reactor- (" NaOH-o)
C NaOH , f 2 0.1 M
2
0.0/ 6 o!ume of unreacted 5uenchin& H"!- ( 3)
C NaOH , s × V 1 C HCl, s 0.1 M
0.25 M
x 21.8 mL
D.>3 m1 o!. of H"! reacted with NaOH in samp!e- ( ,)
V HCl , s−V 2 *0 m1 D.>3 m1 *.3D m1 6o!es of H"! reacted with NaOH in samp!e- (n *)
C NaOH ,s× 0.25 M
V 3 1000
x 1.28 mL
1000
,.3 x *07+ 6o!es of unreacted NaOH in samp!e- (n 3)
n2 n1 ,.3 x *0 7+ =
"onc. of unreacted NaOH in the reactor- (" NaOH)
n2 V s 1000 3.2 x 10 − 4
50
× 1000
B.+ x *0
mol L
7,
"onversion of NaOH in the reactor- @
(
1−
)
C NaOH × 100 C NaOH ,o 6.4 x 10− 3
(* ‒
) x 100
0.05
= 87.2
A. $eaction rate constant
: (" AO7 "A) 3
Ƭ" A
= 0.05 ‒ (B.+ x *0 7,) 300 ‒ (B.+ x *0 7,)3
/.,33, 7r A "A3 3.*D00 x *0
7+
m s
Conductivity vs Conv!sion 16 14 f(x) = - 3.46x + 16.67
12 10
Conductivity (m%&cm)
8 6 4 2 0
0
25
50
Conv!sion" # ($)
75
100
Iraph *
conv!sion vs !sidnc tim 87.5 87 f(x) = 0.01x + 84.'2 86.5 86
Conv!sion"# ($) 85.5 85 84.5 84 60
80
100
120
140
160
180
200
220
sidnc tim (min)
Iraph 3
&.0 DISCUSSION
The Experiment is conducted to determine the reaction rate constant and a!so to determine the effect of residence time on the conversion in a continuous stirred tan reactor ("#T$). "ontinuous stirred tan reactor (6ode! 8 *+,) is used in this experiment to predict the behaviour of chemica! reactor thus- the dimension of the reactor can be estimated. The experiment is conducted with settin& up the f!ow rate of both NaOH and Et(Ac) into 0.*0 12min- and the experiment are repeated by usin& different va!ue of f!owrate which are 0.*/
12min- 0.30 12min- 0.3/ 12min and 0.,0 12min. 4rom the experiment conducted- the data shown that when the f!ow rates of the reactant in the reactor become hi&her- the residence time tends to decrease. $esidence time is nown as the remova! time which is the avera&e amount of time that a partic!e spends in a particu!ar system. 't can be said that the re!ationship between the f!ow rates and the residence time is inverse!y proportiona!. 4rom the data obtained from the experiment- &raph conductivity versus residence of time is p!otted. 4rom the &raph we can see that the va!ue that we &et from the experiment have some error. Iraph that we supposed to &et is conversion is direct!y proportiona! to the residence time which is the va!ue of conversion wi!! be increase as the time increase Jbut the resu!t that we obtained from the experiment are at 0.*0 12min the va!ue of conversion is D>.3=- at 0.*/ 12min the va!ue of conversion is dropped to D/.3= but at 0.30 12min the va!ue of conversion is raised bac to DB.0=- at 0.3/ 12min the va!ue of conversion continued to raised to D>.3= and after that the va!ue of conversion dropped bac to D/.3= for f!ow rate 0.,0 12min. 4rom the observation the va!ue obtained does not fit the theoretica! theory for this experiment. #o we assume that durin& conductin& the experiment some error must have occur.
10.0 CONCLUSION
4or this experiment- continuous stirred tan reactor ("#T$) is used. The objective for this experiment is to determine the reaction rate constant and a!so the effect of residence time on the conversion. 4rom the resu!ts that we obtained we now that some errors does occur durin& the experiment that effect the resu!t. The theoretica! resu!t that shows that the &raph for conversion vs residence time must be direct!y proportiona! but the resu!t that obtained from the experiment show some f!uctuated in the &raph. #o we considered as the experiment does not achieved its objectives.
11.0 RECO!!ENDATION
*. 6ae sure reactor does not have any !eas and va!ve c!osed and opened as neededcontro!!ed the va!ve carefu!!y and s!ow!y when adjustin& the f!ow rate to obtain 0.*0 12min. 6ae sure that the f!ow rate stab!e then start the experiment. 3. To &et a better resu!t- on!y one person is needed to tae care of the openin& and c!osin& of the va!ve and other person tae care of the pump. This is because some va!ve needed to be opened or c!osed simu!taneous!y.
,. 6ae sure the tan is fi!!ed with the correct so!ution and to the correct amount. ?ifferent substance reacts different!y and !ac of substance can dama&e the apparatus. +. 6ae sure &enera! start7up procedure is done first in order to chec the machine functiona!ity.
/. #odium hydroxide is corrosive to f!esh and it can cause b!indness. To prevent this from happen- eye protection shou!d be wear at a!! the time and mae sure to wear &!oves when dea!in& with it. B. A!! of the apparatus shou!d be rinse proper!y to avoid any reaction happen before testin& it. Cash and dry it proper!y in order to &et accurate resu!t especia!!y for titration. >. $epeat the titrationsnfor two or three times because a !ot of error comes from titration.
12.0 REFERENCE
*. 1evenspie!- O.- "hemica! $eaction En&ineerin&- ,rd ed.-Kohn Ci!ey and #ons- New Lor- *.
3. $etrieved **th Apri! 30*B - from https822en.wiipedia.or&2wii2#odiumMhydroxide#aponification ,. $etrieved **th Apri! 30*B - from https822en.wiipedia.or&2wii2"ontinuousMstirred7tanMreactor +. $etrieved **th Apri! 30*B - from http822www.umich.edu2e!ements2/e2asy1earn2bits2cstr2index.htm /. $etrieved **th Apri! 30*B - from http822encyc!opedia.che.en&in.umich.edu2a&es2$eactors2"#T$2"#T$.htm!
13.0 APPENDI"
