Thiele Modulus Formula:
From: | To: |
Definition: The Thiele Modulus for Deactivation is a dimensionless number that relates the reaction rate to the diffusion rate in a catalyst particle undergoing deactivation.
Purpose: It helps chemical engineers determine the effectiveness factor of a catalyst and predict how deactivation affects reaction performance.
The calculator uses the formula:
Where:
Explanation: The formula compares the reaction rate (numerator) to the diffusion rate (denominator), scaled by the characteristic pore length.
Details: Understanding the Thiele Modulus helps in catalyst design, predicting deactivation effects, and optimizing reactor performance.
Tips: Enter the pore length, rate constant, catalyst activity, and diffusion coefficient. All values must be positive numbers.
Q1: What does a high Thiele Modulus indicate?
A: A high value suggests diffusion limitations are significant, meaning the reaction occurs primarily near the pore entrance.
Q2: How does deactivation affect the Thiele Modulus?
A: As the catalyst deactivates, the activity (a) decreases, which typically reduces the Thiele Modulus.
Q3: What's a typical range for catalyst activity?
A: Activity typically ranges from 0 (completely deactivated) to 1 (fully active), though values can exceed 1 for some promoted catalysts.
Q4: How do I determine the diffusion coefficient?
A: The diffusion coefficient can be measured experimentally or estimated from correlations based on temperature and molecular properties.
Q5: What's the relationship between Thiele Modulus and effectiveness factor?
A: The effectiveness factor can be calculated from the Thiele Modulus - for a first-order reaction, η = tanh(MT)/MT.