Chapter 3 Example

Oxidation of Naphthalene to Phtahalic Anhydride

Taking A as the basis of calculation, A + 9/2 B → C + 2D + 2E

We are going to rework the class problem for the case of 3.5% naphthalene and 96.7% air and for a pressure of 10 atm and a temperature of 500K. A feed under these conditions naphthalene is the limiting reactant.

Stoichiomentric Table - Batch System

Species	Symbol	In	Change	Out
Naphthalene	A	N_A0	-N_A0X	N_A = N_A0(1-X)
Oxygen	B	N_B0 = N_A0	-9/2N_A0X	N_B = N_A0( - 9/2X)
Phthalic Anhydride	C	N_C = 0	+N_A0X	N_C = N_A0X
Carbon Dioxide	D	N_D = 0	+2N_A0X	N_D = 2N_A0X
Water	E	N_E = 0	+2N_A0X	N_E = 2N_A0X
Nitrogen	I	N_I = N_A0	---	N_I = N_A0
Total		N_T0		N_T = N_T0 + N_A0X
				= [1 + 2 + 2 - 9/2 - 1] = -1/2

Stoichiometric Table - Flow System

Species	Symbol	In	Change	Out
Naphthalene	A	F_A0	-F_A0X	F_A = F_A0(1-X)
Oxygen	B	F_B0 = F_A0	-9/2F_A0X	F_B = F_A0( - 9/2X)
Phthalic Anhydride	C	F_C = 0	+F_A0X	F_C = F_A0X
Carbon Dioxide	D	F_D = 0	+2F_A0X	F_D = 2F_A0X
Water	E	F_E = 0	+2F_A0X	F_E = 2F_A0X
Nitrogen	I	F_I = F_A0	---	F_I = F_A0
Total		F_T0		F_T = F_T0 + F_A0X

Determine each of the following soley as a function of the conversion of naphthalene, X for a constant-pressureisothermal flow reactor.
1. Find the concentration of O₂
  Gas Phase Flow System:
  
  Constant pressure and isothermal: P = P_o; T = T_o
2. Find the volumentric flowrate
  
  Constant pressure and isothermal: P = P_o; T = T_o
3. Find the reaction rate
  
  Rate Law: -r_A = k_AC²_AC_B

For a constant volume isothermal batch reactor,

The concentration of O₂
For Batch: V = V₀, C_B = N_B/V = N_B/V₀
The total pressure, P.
The rate law
Rate Law: -r_A = k_AC²_AC_B

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