Question

Consider a continuous, steady- state process in which the following two reactions take place:

C₆H₁₂ + 6H₂O → 6CO + 12H₂

C₆H₁₂ + H₂ → C₆H₁₄

In the process, 250 moles of C₆H₁₂ and 800 moles of H₂O are fed into the reactor each hour. The yield of H₂ is 40.0% and the selectivity of H₂ over C₆H₁₄ is 12.0. There is incomplete conversion of the reactants, i.e., both reactants are also present in the output stream.

Draw a fully labeled process flowchart, and perform a degree of freedom analysis (using any method you wish; molecular species method, atomic species method, or extent of reaction method) to show that the problem is completely defined.

Answer 1

Creating a process flowchart for the given chemical reactions requires incorporating feed rates, reaction vessels, and product streams with known yields and selectivities. Degree of freedom analysis, based on the mass balance equations and the given data, ensures the problem is fully defined and solvable.

Step-by-step explanation:

The given continuous, steady-state process involves two reactions with known feed rates and given product yields and selectivities. To create a fully labeled process flowchart, it's necessary to incorporate the feed streams, reaction vessels, and product streams, followed by identifying the knowns and unknowns of the process. A degree of freedom analysis can be performed to determine if the system is fully defined.

A step by step explanation includes first establishing the molar flow rates of the feed streams, in this case, 250 moles/hour of C₆H₁₂ and 800 moles/hour of H₂O. Using the yield and selectivity information, the molar flow rates of the products can be deduced. The yield of H₂ gives the quantity of H₂ formed, and the selectivity of H₂ over C₆H₁₄ allows the determination of the amount of C₆H₁₄ produced in relation to H₂. Assessment of any excess reactants in the output should also be included in the flowchart.

For the degree of freedom analysis, identify the number of independent variables (unknowns) and equations (relationships that can be made between variables) to see if the system of equations is solvable (the degrees of freedom should be zero).