On the dehydrogenation of isobutane to isobutylene
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Xiaobai is seeking help – he wants to produce high-purity isobutylene through isobutane dehydration. Why, after isobutane dehydration yields isobutylene, cannot isobutane and isobutylene be separated directly to obtain high-purity isobutylene? Why is it necessary to use an MTBE unit to achieve high-purity isobutylene? Thank you!
Isobutane, which is generally used for dehydration, is not pure isobutane either; it is a mixed hydrocarbon containing various C4 components, namely liquefied gas. During catalytic dehydrogenation, in addition to the dehydrogenation of isobutane, other alkanes also undergo dehydrogenation, along with some isomerization reactions. Since the boiling points of the C4 components differ little, it is difficult to separate components with similar boiling points using distillation. By using the MTBE reaction, it is possible to selectively separate MTBE from the liquefied gas mixture; subsequent decomposition then yields gaseous isobutylene and liquid methanol. The isobutylene obtained in this way has a high purity, and the operational costs are also low.