CRE-Peer Discussion - Session-3

Karthikeyan explained two questions from CRE-2 related to catalyst activity and reaction mechanisms. For the first question, he described how to calculate the catalyst activity at \(t = 10\) using the given rate equation and initial activity of 100%. For the second question, he detailed the steps to find the ratio of CO to H2 occupied sites on a catalyst surface using equilibrium constants and the fraction of vacant sites.

Karthikeyan explained the concept of residence time distribution (RTD) and its importance in non-ideal reactors, emphasizing the need for tracer experiments to account for non-idealities that can affect actual conversions. He discussed the design equation for a continuous stirred-tank reactor (CSTR) and highlighted that the rate of reaction is equal for a given conversion in both batch reactors and CSTRs under ideal conditions. Karthikeyan also described how RTD data can be used to calculate the average conversion at the reactor exit, accounting for the effects of non-ideal reactor behavior.

Karthikeyan explained the integration process for a second-order reaction, deriving equations for conversion over time and using the concept of \(e^{-kt}\) to find actual reactor conversions. He demonstrated how to convert a graphical representation of \(e^{-kt}\) into a function of time and described the method to solve the problem by integrating \(e^{-kt}\) between specific time limits, focusing on the area under the curve.

Karthikeyan explained the solution process for a second-order reaction problem involving integration and calculation of rate equations. He emphasized the importance of accurate calculations and mentioned that similar topics could appear in upcoming exams. Karthikeyan also discussed a simpler problem involving a first-order reaction and encouraged students to practice before checking the solutions. Finally, he introduced a new problem involving two parallel reactions in an isothermal batch reactor, advising students to carefully read the question before attempting the solution.

Karthikeyan explained the process of solving for k1 and k2 using two equations derived from the given concentrations and reaction conditions. He demonstrated the calculations step-by-step, arriving at the final values for k1 and k2. Janarth then introduced the topic of non-ideal reactors and heterogeneous reactions, mentioning that the discussion would cover various types of problems including E-Curves and residence time distributions.

Janarth explained the solution process for several types of reactor problems. He described how to derive the exit age distribution equation for an ideal CSTR and outlined the steps to solve problems involving tracer curves and mean residence times for both triangle and rectangular distributions. Janarth also explained the concepts of dispersion number and packet number for plug flow reactors and CSTRs, noting that the packet number for an ideal plug flow reactor is infinite while it is zero for a CSTR. He concluded by mentioning that he would move on to discuss a hexose generative reaction problem using the Langmuir-Hinshelwood model.

Janarth explained the process of solving problems related to the rate of reaction in heterogeneous catalysis, focusing on the adsorption and desorption of molecules A, B, and C on a catalyst surface. He outlined the steps to derive the rate equation, including writing expressions for the rate of adsorption and desorption, equating them at equilibrium, and substituting values to solve for the rate of reaction. Janarth emphasized that understanding these concepts would help in solving both mechanism-based and equilibrium-based problems, and he mentioned that the next session would focus on process control starting the following Sunday.