To solve this problem, we need to go through several steps. Let’s break down each part of the problem and solve it one by one:

Problem Summary and Key Information:

We have a gas-phase elementary reaction: $(\text{CH}_3)_3\text{COOC}(\text{CH}_3)_3 \rightarrow \text{C}_2\text{H}_6 + \text{CH}_3\text{COCH}_3$

The reactor is operated isothermally in a plug flow reactor (PFR) with no pressure drop.

Key dataTo solve this problem, we need to go through several steps. Let’s break down each part of the problem and solve it one by one:

Problem Summary and Key Information:

We have a gas-phase elementary reaction: $(\text{CH}_3)_3\text{COOC}(\text{CH}_3)_3 \rightarrow \text{C}_2\text{H}_6 + \text{CH}_3\text{COCH}_3$

The reactor is operated isothermally in a plug flow reactor (PFR) with no pressure drop.

Key

• Reaction rate constant at 50°C ($k_{50}$) = $3 \times 10^{-4} \, \text{min}^{-1}$
• Activation energy ($E_a$) = 85 kJ/mol
• Inlet molar flow rate ($F_{A0}$) = 1.5 mol/min
• Temperature ($T$) = 127°C
• Pressure = 4 atm
• Desired conversion ($X$) = 60%

Constants and Conversions:

• Convert temperature to Kelvin for calculations: $T_{\text{reaction}} = 127 + 273 = 400 \, \text{K}$
• Activation energy should be converted to consistent units if needed, e.g., $E_a = 85000 \, \text{J/mol}$.

Step-by-Step Solution:

(A) Calculate the Volume of the PFR

1. Arrhenius Equation: First, calculate the rate constant $k$ at 127°C using the Arrhenius equation: $k = k_{50} \times e^{\left(\frac{E_a}{R} \left(\frac{1}{T_{50}} - \frac{1}{T}\right)\right)}$ where:

   • $R = 8.314 \, \text{J/(mol K)}$
   • $T_{50} = 50 + 273 = 323 \, \text{K}$

2. Mole Balance for PFR: Using the design equation for a PFR: $V = \frac{F_{A0} X}{-r_A}$ The rate of reaction $-r_A$ can be calculated using: $-r_A = k C_{A0} (1 - X)$ where $C_{A0}$ is the initial concentration, found from the ideal gas law: $C_{A0} = \frac{P}{RT}$

3. Substitute values and solve for $V$.

(B) Calculate the Space Time

The space time $\tau$ in a PFR is given by: $\tau = \frac{V}{F_{A0}}$

(C) Calculate the Concentration of Acetone and Ethane Formed

Since acetone and ethane are formed at a 1:1 molar ratio with the reactant, their concentrations can be calculated based on the conversion. Specifically: $C_{\text{acetone}} = C_{\text{ethane}} = C_{A0} \times X$

(D) Calculate the Conversion for a CSTR in Series with the PFR

For a CSTR, the conversion is given by: $X_{\text{CSTR}} = \frac{X_{\text{PFR}}}{1 + X_{\text{PFR}}}$ where $X_{\text{PFR}} = 0.7$ (from the problem statement).

Would you like me to proceed with detailed calculations for each step?

Related Questions

1. How does the Arrhenius equation affect the rate constant as temperature increases?
2. What is the impact of pressure on the concentration of gases in the reactor?
3. How does the choice of reactor (PFR vs. CSTR) influence the final conversion?
4. Can we use the ideal gas law in non-ideal gas conditions in reactors?
5. Why is activation energy important in chemical kinetics?

Tip

In chemical reactor design, understanding the differences between PFR and CSTR can be critical, as they yield different conversions and space times for the same reaction conditions.