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4.67. Methane and oxygen react in the presence of a catalyst to form formaldehyde. In a parallel reaction, methane is oxidized to carbon dioxide and water: CH4 + O₂ HCHO + H₂O CH4 +202 → CO₂ + 2H₂O The feed to the reactor contains equimolar amounts of methane and oxygen. Assume a basis of 100 mol feed/s. (a) Draw and label a flowchart. Use a degree-of-freedom analysis based on extents of reaction to determine how many process variable values must be specified for the remaining variable values to be calculated. (b) Use Equation 4.6-7 to derive expressions for the product stream component flow rates in terms of the two extents of reaction, ₁ and 2. (c) The fractional conversion of methane is 0.900 and the fractional yield of formaldehyde is 0.855. Calculate the molar composition of the reactor output stream and the selectivity of formaldehyde production relative to carbon dioxide production. (d) A classmate of yours makes the following observation: "If you add the stoichiometric equations for the two reactions, you get the balanced equation 2CH4 + 302 HCHO + CO₂ + 3H₂O The reactor output must therefore contain one mole of CO₂ for every mole of HCHO, so the selectivity of formaldehyde to carbon dioxide must be 1.0. Doing it the way the book said to do it, I got a different selectivity. Which way is right, and why is the other way wrong?" What is your response?

4.67. Methane and oxygen react in the presence of a catalyst to form formaldehyde. In a parallel reaction, methane is oxidized to carbon dioxide and water: CH4 + O₂ HCHO + H₂O CH4 +202 → CO₂ + 2H₂O The feed to the reactor contains equimolar amounts of methane and oxygen. Assume a basis of 100 mol feed/s. (a) Draw and label a flowchart. Use a degree-of-freedom analysis based on extents of reaction to determine how many process variable values must be specified for the remaining variable values to be calculated. (b) Use Equation 4.6-7 to derive expressions for the product stream component flow rates in terms of the two extents of reaction, ₁ and 2. (c) The fractional conversion of methane is 0.900 and the fractional yield of formaldehyde is 0.855. Calculate the molar composition of the reactor output stream and the selectivity of formaldehyde production relative to carbon dioxide production. (d) A classmate of yours makes the following observation: "If you add the stoichiometric equations for the two reactions, you get the balanced equation 2CH4 + 302 HCHO + CO₂ + 3H₂O The reactor output must therefore contain one mole of CO₂ for every mole of HCHO, so the selectivity of formaldehyde to carbon dioxide must be 1.0. Doing it the way the book said to do it, I got a different selectivity. Which way is right, and why is the other way wrong?" What is your response?

Introduction to Chemical Engineering Thermodynamics
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
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### Problem 4.67: Methane and Oxygen Reactions Methane and oxygen react in the presence of a catalyst to form formaldehyde. In a parallel reaction, methane is oxidized to carbon dioxide and water as shown in the reactions below: - \( \text{CH}_4 + \text{O}_2 \rightarrow \text{HCHO} + \text{H}_2\text{O} \) - \( \text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O} \) The feed to the reactor contains equimolar amounts of methane and oxygen. Assume a basis of 100 mol feed/s. #### Tasks: (a) **Flowchart and Degree-of-Freedom Analysis** Draw and label a flowchart. Use a degree-of-freedom analysis based on extents of reaction to determine how many process variable values must be specified for the remaining variable values to be calculated. (b) **Expressions for Product Stream** Use Equation 4.6-7 to derive expressions for the product stream component flow rates in terms of the two extents of reaction, \( \xi_1 \) and \( \xi_2 \). (c) **Molar Composition and Selectivity** The fractional conversion of methane is 0.900 and the fractional yield of formaldehyde is 0.855. Calculate the molar composition of the reactor output stream and the selectivity of formaldehyde production relative to carbon dioxide production. (d) **Classmate Observation** A classmate observes: “If you add the stoichiometric equations for the two reactions, you get the balanced equation: \( 2\text{CH}_4 + 3\text{O}_2 \rightarrow \text{HCHO} + \text{CO}_2 + 3\text{H}_2\text{O} \) Thus, the reactor output must contain one mole of \( \text{CO}_2 \) for every mole of \( \text{HCHO} \), so the selectivity of formaldehyde to carbon dioxide must be 1.0. Which way is right, and why is the other way wrong?” What is your response? --- This problem involves performing a reaction and process analysis using stoichiometry, reaction extents, and selectivity calculations. Make
Transcribed Image Text:### Problem 4.67: Methane and Oxygen Reactions Methane and oxygen react in the presence of a catalyst to form formaldehyde. In a parallel reaction, methane is oxidized to carbon dioxide and water as shown in the reactions below: - \( \text{CH}_4 + \text{O}_2 \rightarrow \text{HCHO} + \text{H}_2\text{O} \) - \( \text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O} \) The feed to the reactor contains equimolar amounts of methane and oxygen. Assume a basis of 100 mol feed/s. #### Tasks: (a) **Flowchart and Degree-of-Freedom Analysis** Draw and label a flowchart. Use a degree-of-freedom analysis based on extents of reaction to determine how many process variable values must be specified for the remaining variable values to be calculated. (b) **Expressions for Product Stream** Use Equation 4.6-7 to derive expressions for the product stream component flow rates in terms of the two extents of reaction, \( \xi_1 \) and \( \xi_2 \). (c) **Molar Composition and Selectivity** The fractional conversion of methane is 0.900 and the fractional yield of formaldehyde is 0.855. Calculate the molar composition of the reactor output stream and the selectivity of formaldehyde production relative to carbon dioxide production. (d) **Classmate Observation** A classmate observes: “If you add the stoichiometric equations for the two reactions, you get the balanced equation: \( 2\text{CH}_4 + 3\text{O}_2 \rightarrow \text{HCHO} + \text{CO}_2 + 3\text{H}_2\text{O} \) Thus, the reactor output must contain one mole of \( \text{CO}_2 \) for every mole of \( \text{HCHO} \), so the selectivity of formaldehyde to carbon dioxide must be 1.0. Which way is right, and why is the other way wrong?” What is your response? --- This problem involves performing a reaction and process analysis using stoichiometry, reaction extents, and selectivity calculations. Make
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