Patent ID: 6121505
Filing Date: 2000-09-19
Classification: C07C

Abstract:
A process for the production of olefins and hydrogen by dehydrogenation of at least one paraffin, comprising providing a hydrocarbon feed and:a) introducing a first fraction of said hydrocarbon feed comprising at least one paraffin containing at least two carbon atoms into a dehydrogenation reaction zone in the presence of hydrogen kept under dehydrogenation conditions to produce at least one reaction effluent containing at least one olefin, hydrogen and an unconverted fraction of said feed;b) bringing the reaction effluent obtained from step a) into counter-current contact with a heavy hydrocarbon fraction in an absorption zone under absorption conditions to produce at least one first gaseous hydrocarbon fraction and a first liquid hydrocarbon fraction, wherein the first gaseous hydrocarbon fraction comprises the majority of the hydrogen initially present in the effluent from step a), a portion of said heavy hydrocarbon fraction, and light hydrocarbon compounds, and wherein the first liquid hydrocarbon fraction comprises the majority of said heavy hydrocarbon fraction, the olefin and the unconverted fraction of said paraffin;c) recovering a first portion of the first gaseous hydrocarbon fraction containing hydrogen separated in step b) and sending a second portion of the first gaseous hydrocarbon fraction containing hydrogen to a second step comprising bringing said second portion into counter-current contact with a light hydrocarbon fraction in an absorption zone under absorption conditions to produce at least one second gaseous fraction and a second liquid hydrocarbon fraction, wherein the second gaseous fraction comprises the majority of the hydrogen initially present in the gaseous fraction of step b) and the majority of said light hydrocarbon fraction; recycling at least a portion of said second gaseous fraction to dehydrogenation step a), wherein said second liquid hydrocarbon fraction comprises a portion of said light hydrocarbon fraction and a portion of said heavy hydrocarbon fraction used in step b), and recovering said second liquid hydrocarbon fraction;wherein the light hydrocarbon fraction used in step c) comprises second fraction of the hydrocarbon feed.