Problem
Ethylene oxide (EO, 1400 $/metric ton) is industrially produced via the selective partial oxidation of ethylene (400 $/metric ton) in a packed bed reactor (PBR) over a Ag catalyst, but the process is not 100 % selective to EO. On average, it is expected that approximately 10% of the carbon fed in the form of ethylene to the PBR will over-oxidize to CO2 when using air as an oxygen source, while the remainder will partially oxidize to the desired EO. Alternatively, if pure molecular oxygen is used, the selectivity to EO increases depending on the reaction conditions applied. As a process engineer, you are tasked with determining the following:
A. What is the economic potential of EO production using air? Report your answer per metric ton of EO.
B. The United States Congress recently passed the Climate Action Rebate Act of 2019 (CAR Act), which would impose a tax of $15 per metric ton of CO2. What is your new economic potential? Report your answer per metric ton of EO.
C. Unsure whether the CAR Act will become a law (see schoolhouse rock), you seek to understand how sensitive your process is to the proposed legislation. Construct a sensitivity analysis that accounts for the cost of CO2.
D. How much carbon tax can you pay before losing positive economic potential? Report your answer in units of $ per metric ton of CO2.
E. In an effort to reduce your carbon tax, you investigate the use of purified molecular oxygen as opposed to air. Assuming an industrial price of $40 per metric ton of O2, should you use air and accept the carbon tax, or use purified O2 and reduce a carbon tax? Assume complete selectivity to EO when using O2.
F. What are other considerations that can be considered in part (E)?