Upgrading C4 mixed hydrocarbons by transhydrogenation and isobutene etherification

In the process for converting olefinic light hydrocarbons rich in butenes and butanes to ether, wherein a mixed C4 hydrocarbon stream containing isobutene and n-butenes is reacted with lower aliphatic alcohol to produce C5+tertiary-alkyl ether;

• the improvement which comprises:
• separating etherification effluent to provide a liquid stream comprising C5+ether and an olefinic stream comprising unreacted C4 hydrocarbons including n-butene;
• contacting the n-butene from the C.sub.4 olefinic hydrocarbon stream with added isobutane under transhydrogenation conditions in the presence of transhydrogenation catalyst whereby isobutane is converted to isobutene;
• separating transhydrogenation effluent to recover a C4 olefinic stream rich in isobutene;
• and
• recycling at least a portion of the isobutene-rich for et further etherification.

A process for converting olefinic light hydrocarbons rich in butenes and butanes to methyl t-butyl ether (MTBE), comprising the steps of:

• reacting a mixed C4 hydrocarbon stream containing isobutene and n-butenes with methanol in an etherification zone in contact with an acidic etherification catalyst under etherification conditions whereby an effluent stream containing MTBE is produced;
• separating the etherification effluent stream to provide a liquid stream comprising MTBE and an olefinic stream comprising unreacted C4 hydrocarbons;
• and
• contacting at least the n-butenes from the C.sub.4 olefinic hydrocarbon stream with isobutane under transhydrogenation conditions in the presence of transhydrogenation catalyst whereby isobutane is converted to isobutene.