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. The reactions are as follow:
CH4 + 0₂ → HCHO + H₂O ->
CH4 +20₂ → CO₂ + 2H₂O
A stream containing methane and oxygen with a molar ratio of 1:2 is joined by a recycle stream containing pure methane, and the combined stream is fed to the reactor. The reactor effluent goes through a separation process that has three outlet streams. The first stream, which is sold, is pure formaldehyde; the second, which is discarded, contains all the carbon dioxide, oxygen, water, and 5% of the unreacted methane leaving the reactor; and the third stream, which is the recycle stream, contains the remaining unreacted methane. With a complete drawing of the process:
a) By using a relevant reference with regards to the above reaction and process, assume the inlet and outlet temperature of the reactor.
(4 marks)
b) Using the information from (a), determine the heat released/absorbed by the reactor. Taking 50 mol/s of methane in the fresh feed as a basis of calculation. Please state other assumption/s to solve the calculation. Your assumption/s must only refer to conversion or/and selectivity of the process.
Answers
Explanation:
catalyst to form formaldehyde. In a parallel reaction, methane is oxidized to carbon dioxide and water. The reactions are as follow:
CH4 + 0₂ → HCHO + H₂O ->
CH4 +20₂ → CO₂ + 2H₂O
A stream containing methane and oxygen with a molar ratio of 1:2 is joined by a recycle stream containing pure methane, and the combined stream is fed to the reactor. The reactor effluent goes through a separation process that has three outlet streams. The first stream, which is sold, is pure formaldehyde; the second, which is discarded, contains all the carbon dioxide, oxygen, water, and 5% of the unreacted methane leaving the reactor; and the third stream, which is the recycle stream, contains the remaining unreacted methane. With a complete drawing of the process:
a) By using a relevant reference with regards to the above reaction and process, assume the inlet and outlet temperature of the reactor.
(4 marks)
b) Using the information from (a), determine the heat released/absorbed by the reactor. Taking 50 mol/s of methane in the fresh feed as a basis of calculation. Please state other assumption/s to solve the calculation. Your assumption/s must only refer to conversion or/and selectivity of the process