The ethylene epoxydation is to be carried out using a cesium-doped silver catalyst in a pa...

The ethylene epoxydation is to be carried out using a cesium-doped silver catalyst in a packed bed reactor.

Along with the desired reaction, the complete combustion of ethylene also occurs

[M. Al-Juaied, D. Lafarga, and A. Varma, Chem. Eng. Sci. 56, 395 (200 1)]. It is proposed to replace the conventional PBR with a membrane reactor in order to improve the selectivity. As a rule of thumb, a 1% increase in the selectivity to ethylene oxide translates to an increase in profit of about $2 million/ yr. The feed consists of 12% (mole) oxygen, 6% ethylene, and the remainder nitrogen at a temperature of 250̊ C and a pressure of 2 atm. The total molar flow rate is 0.0093 molls to a reactor containing 2 kg of catalyst.

(a) What conversion and selectivity, Ŝ, are expected in a conventional PFR?

(b) What would be the conversion and selectivity if the total molar flow rate were divided and the 12% oxygen stream (no ethylene) were uniformly fed through the sides of the membrane reactor and 6% ethylene (no oxygen) were fed at the entrance?

(c) Repeat (b) for a case where ethylene is fed uniformly through the sides and oxygen is fed at the entrance. Compare with parts (a) and (b).

(d) Repeat (b) and (c) for the methanol reaction given in P6-9c (h) with Pi in bar and -rlicH2OH and - r2cH2o are in bar/s.