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Solved: A catalytic reactor is used to produce
Chapter 4, Problem 4.75(choose chapter or problem)
A catalytic reactor is used to produce formaldehyde from methanol in the reaction CH3OH ! HCHO H2 A single-pass conversion of 60.0% is achieved in the reactor. The methanol in the reactor product is separated from the formaldehyde and hydrogen in a multiple-unit process. The production rate of formaldehyde is 900.0 kg/h. (a) Calculate the required feed rate of methanol to the process (kmol/h) if there is no recycle. (b) Suppose the unreacted methanol is recovered and recycled to the reactor and the single-pass conversion remains 60%. Without doing any calculations, prove that you have enough information to determine the required fresh feed rate of methanol (kmol/h) and the rates (kmol/h) at which methanol enters and leaves the reactor. Then perform the calculations. (c) The single-pass conversion in the reactor, Xsp, affects the costs of the reactor Cr and the separation process and recycle line Cs. What effect would you expect an increased Xsp would have on each of these costs for a fixed formaldehyde production rate? (Hint: To get a 100% singlepass conversion you would need an infinitely large reactor, and lowering the single-pass conversion leads to a need to process greater amounts of fluid through both process units and the recycle line.) What would you expect a plot of Cr Cs versus Xsp to look like? What does the design specification Xsp 60% probably represent?
Questions & Answers
QUESTION:
A catalytic reactor is used to produce formaldehyde from methanol in the reaction CH3OH ! HCHO H2 A single-pass conversion of 60.0% is achieved in the reactor. The methanol in the reactor product is separated from the formaldehyde and hydrogen in a multiple-unit process. The production rate of formaldehyde is 900.0 kg/h. (a) Calculate the required feed rate of methanol to the process (kmol/h) if there is no recycle. (b) Suppose the unreacted methanol is recovered and recycled to the reactor and the single-pass conversion remains 60%. Without doing any calculations, prove that you have enough information to determine the required fresh feed rate of methanol (kmol/h) and the rates (kmol/h) at which methanol enters and leaves the reactor. Then perform the calculations. (c) The single-pass conversion in the reactor, Xsp, affects the costs of the reactor Cr and the separation process and recycle line Cs. What effect would you expect an increased Xsp would have on each of these costs for a fixed formaldehyde production rate? (Hint: To get a 100% singlepass conversion you would need an infinitely large reactor, and lowering the single-pass conversion leads to a need to process greater amounts of fluid through both process units and the recycle line.) What would you expect a plot of Cr Cs versus Xsp to look like? What does the design specification Xsp 60% probably represent?
ANSWER:Step 1 of 4
Catalytic reactor
Substances that increase the reaction rate by providing an alternative path of lower energy are called catalysts. They are regenerated at the end of the reaction. The use of catalysts in reactions to produce a bulk amount of chemicals led to the use of reactors.
Catalytic reactors are devices that house the catalysts and the reacting medium. It controls the reaction conditions. Reactants are fed into the reactant, and products are removed to carry out continuous reactions in the reaction space.
Reactors are classified based on their size, fluid flow type, charging methods, and motion of particles with respect to each other. The fluid flow type can be tubular or mixed flow reactors based on the fluid flow type. They are classified into a steady flow and batch reactors based on the charging method.