Question

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^{Problem 4: Ethylene oxide (C2Ha0), an intermediate in the production of plastics, is produced by the partial oxidation of ethylene (Reaction #1) C2H4+ O2 CH4O 25% 1. Reaction #2-the combustion of ethylene to form CO2 and H20-is an undesired side reaction: 2. C2H4+ O2 CO2 H20 (Note: This reaction is not balanced) Assume no other reactions occur-specifically that recycled ethylene oxide is not further oxidized. Pure oxygen (not air) is used in the process. A schematic diagram of the process is shown below. In order to suppress the undesired side reaction, the ratio of ethylene to oxygen in the reactor is kept at a minimum of 3 (i.e. (moles CHa/moles O2)ceactor> 3). This is accomplished by adding extra ethylene to the reactor before the operation is initiated. A catalyst that is selective to the desired reaction is used. 20 % of the ethylene in stream # 1 reacts in a single pass thru the reactor and the selectivity is 90% by reaction #1. A sophisticated separation process, designated as Sep. 1, recovers all the unreacted ethylene and oxygen along with 4% of the reaction products and recycles it in stream #4. The second separation process, designated as Sep. 2, recovers all of the ethylene oxide in stream #3 and vents the cO2 and H20 (waste) to the atmosphere Calculate the steady state moles of O2 per mole of C2H4 in the feed stream. Hint: This is supposed to be an easy problem. Don't make it hard. Write the overall balances -co2+ H20 (waste) Feed 1 Reactor 2 Sep. 1 Sep. 2 C2H4+O2 CH4O (Desired Product)}

Answer 1

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