A high value of the Thiele modulus during a biochar particle conversion process corresponds to a Regime I conversion. Right or wrong?

Thiele modulus (φ) is a dimensionless number that helps us evaluate the relative rates of diffusion and reaction in porous catalyst particles. In a nutshell, it is used to describe how fast the diffusion of reactants/products is occurring compared to the reaction rate in the catalyst particle. A high Thiele modulus corresponds to slow diffusion rates, whereas a low Thiele modulus corresponds to fast diffusion rates.

There are three different diffusion regimes during a biochar particle conversion process: 1. Regime I: When the Thiele modulus is high, diffusion is slow, and the reaction rate is limited by diffusion. This means that the reaction is happening faster than the reactants can diffuse into the catalyst particle or the products can diffuse out of the particle. As a result, the reaction takes place near the surface of the catalyst particle. 2. Regime II: When the Thiele modulus is around 1, the reaction rate and the diffusion rate are comparable, and neither controls the overall process. 3. Regime III: When the Thiele modulus is low, diffusion is fast, and the reaction rate is limited by the reaction itself, rather than diffusion of the reactants/products. Since the diffusion rate is much higher, the reaction takes place uniformly throughout the catalyst particle.

The given statement is: "A high value of the Thiele modulus during a biochar particle conversion process corresponds to a Regime I conversion." As we can see from our understanding of the Thiele modulus and the different diffusion regimes, this statement is correct. Regime I occurs when the Thiele modulus is high, which means diffusion is slow and the reaction rate is limited by diffusion.