Vinyl chloride (CH2CHCI) is an important chemical used to synthesize the polymer
ID: 879434 • Letter: V
Question
Vinyl chloride (CH2CHCI) is an important chemical used to synthesize the polymer polyvinyl chloride. Vinyl chloride may be synthesized by a two-step process. First, ethylene is chlorinated to form 1,2-dichlorothane Then the 1,2-dichloroethane is dehydrochlorinated to produce vinyl chloride and hydrogen chloride (2) At this point, the hydrogen chloride may be siphoned off from the vinyl chloride to react with oxygen and more CICH,CH,CI(g) CH,CHCI(g) + HCl(g) ethylene to form 1,2-dichloroethane CICH,CH,CI +H, This newly-formed 1,2-dichloroethane is then free to undergo the reaction (2), creating more CH2CHCl and HCI A facility produces vinyl chloride by the process described above. A 44.0 L/min, 50/50 mixture by mole of ethylene and chlorine gas at 323.15 K and 1.00 atm is fed into Reactor 1, in which reaction (1) takes place. CICH2CH2Cl gas leaves Reactor 1 and enters a preheater where the CICH2CH2Cl is raised to 490.0 K and kept at 1.00 atm. CICH2CH2Cl moves into pressurized Reactor 2 where it undergoes reaction (2). Hydrogen chloride from this reaction is sent to Reactor 3 where it is mixed with stoichiometric amounts of O2 and ethylene and reaction (3) occurs. CICH2CHzCl from reaction (3) is separated from water vapor, and sent to the preheater Find: the molar flow rate of vinyl chloride out of this process, the molar flow rate of ethylene into Reactor 3, the moles of CICH2CH2Cl leaving the preheater, and the velocity of the CICH2CH2CI gas leaving the pre-heater if the pipe's diameter is 5.00 cm. Assume all reactions proceed to completion, no side reactions occur, and all gases behave ideally except CICH2CH2CI. Use the van der Waals equation of state to model the behavior of ClCH2CH2CI (Te = 561.6 K, Pc = 53.8 atm)Explanation / Answer
From ideal gas equation
PV= nRT can be used to find the moles of 50/50 C2H4 and Cl2 entering the first reactor
R=0.0823 lit.atm/.kmole
T=273.15K and V =50 lit/min
n= 1*50/(0.0823*273.15) =2.225 moles/min
Since the mixture is 50/50 ratio
moles of C2H4= 2.25*0.5 =1.125 moles/min
Molo of Cl2 =1.125 moles/min
C2H4+Cl2---- >ClC2H4Cl (1)
Let x moles of C2H4 react through this process
Reamining C2H4 = 1.125-x
1 moles of C2H4 gives rise to 1 mole of C2H4Cl. Hence, moles of ClC2H4Cl formed from this reaction ( since the reactions goes to completion) =x moles/min
C2H4Cl formed from reaction 1 = x moles
This vinyl chlorie (ClC2H4Cl) undergoes dehydrochlorination to prodcuce CH2CHCl. Vinyl chloride formed =x moles and x moles of Hcl is formed,.
ClC2H4Cl-----> CH2CHCl +HCl
Further 2 moles of Hcl reacts with Oxygen ( from reaction 3 to give rise to 1 mole of 1,2 dichloroethane.
The reaaction is
2HCl+C2H4+1/2O2---->ClCH2CH2Cl+ H2O
2x moles of HCl reacts with x moles of C2H4 ( Sicne stoichiometric rations)
x moles react with x/2 moles of C2H4
but C2H4 remaining =1.125-x =x/2
3x/2 =1.125
x = 1.125*2/3 =0.75 moles/min
C2H4 reacted with Cl2 is through reaction (1) =0.75 moles /min
C2H4 Reacted throuh reaction (3) =1.125-0.75= 0.375 moles/min
Molar flow rate of Vinyl chloride (n6) =0.75 moles/min
molar flow rate of ethylene in to the reactor (3) is (n7) =0.375 moles/min
Molar flow rate of ClCH2CH2Cl =0.75 moles/min
From Vandewaal equation
(P+a/V2) (V-b) =nRT
a =27R2Tc2/Pc =27*(0.0823)2 (561.6)2/64*53.8=16.75
where suffix c refer to critical conditions
b= RTc/ 8Pc= 0.0823* 561.1/ (8*53.8) =0.107
P= 1 atm
T= 490K
n= 0.75 moles/ min
(1+16.75/V2)(V-0.107)= 0.75*0.0823*490
on solving V =30.25 lit/min =30.25*10-3 m3/min =30.25*10-3/ 60 m3/sec =0.000504 m3/sec
pipe dia =5 cm =5/100m = 0.05cm
Cross sectional area = (3.142/4)* 0.05^(2) =0.001964m2
Velocity = 0.000504/ 0.001964 =0.2578 m/sec
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