Ethyleneoxide can be made by reaction of ethylene and oxygen using a silver catalyst. This is usually done in a cooled tubular reactor. The desired reaction can be written as:
2 C2H4 + O2 ---> 2 C2H4O
An unwanted reaction (the complete combustion of ethylene) will take place as well:
C2H4 + 3 O2 ---> 2 CO2 + 2 H2O
Both reactions are strong exotherm and therefore the risc of a runaway is a big problem when producing ethylene. The unwanted reaction produces much more heat then the wanted reaction. A catalyst which results in high selectivities can therefore probably be operated at a higher temperature and thus give a higher conversion.
In this study a virtual catalyst with an increased selectivity (90 % instead of 80 %) but a decreased conversion has been compared with the conventional catalyst. A pseudo-homogeneous one-dimensional model was used to describe the process in the tubular reactor.
The study showed that the new catalyst requires a longer reactor, a higher temperature and a higher oxygen concentration for optimal results. If the conditions for the new catalyst are chosen at the same level of safety as for the conventional catalyst the yield will be improved by almost 100 %.