Question 5 The possibility is being investigated of changing the size of the near-spherical catalyst pellets...

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Question 5 The possibility is being investigated of changing the size of the near-spherical catalyst pellets used in a fixed bed tubular reactor in which an irreversible first order reaction is taking place. The pellets currently in use are 4x103 m in diameter and Thiele's modulus for these is known to be 3.0. Temperature gradients within them are negligible. It is proposed to change these to pellets which are 1 mm in diameter but whose properties are otherwise identical. Calculate the ratio of the apparent first order rate constant with the modified pellets to that with the original pellets. A table giving effectiveness factor (ns) as a function of s over part of the relevant range is given below 2.6 2.8 3.0 3.2 3.4 3.6 3.8 0.647 0.722 0.672 0.696 0.624 0.603 0.583 Question 5 The possibility is being investigated of changing the size of the near-spherical catalyst pellets used in a fixed bed tubular reactor in which an irreversible first order reaction is taking place. The pellets currently in use are 4x103 m in diameter and Thiele's modulus for these is known to be 3.0. Temperature gradients within them are negligible. It is proposed to change these to pellets which are 1 mm in diameter but whose properties are otherwise identical. Calculate the ratio of the apparent first order rate constant with the modified pellets to that with the original pellets. A table giving effectiveness factor (ns) as a function of s over part of the relevant range is given below 2.6 2.8 3.0 3.2 3.4 3.6 3.8 0.647 0.722 0.672 0.696 0.624 0.603 0.583