Desorption process wherein a portion of the adsorbate is burned with an oxygen-containing gas utilizing a moving heat front

Claim 1

AN IMPROVED PROCESS FOR DEWAXING MIDDLE DISTILLATE WHICH COMPRISES PASSING A VAPORIZED FEED STREAM OF MIDDLE DISTILLATE BOILING IN THE RANGE OF ABOUT 300-700* F. INTO A ZEOLITIC MOLECULAR SIEVE IN THE ADSORPTION ZONE, MAINTAINING A TEMPERATURE OF ABOUT 400-800*F., PRESSURE OF 0.2 TO 760 MM. AND FEED RATES OF 0.2 TO 2.0 V./V./HR. IN SAID ZONE, ADSORBING WAX IN SAID ZONE, WITHDRAWING FROM SAID ZONE A MIDDLE DISTILLATE OF SUBSTANTIALLY REDUCED POUR POINT, THEREAFTER PASSING A GAS CONTAINING FROM 0.5 TO 20% OXYGEN INTO AN UPPER PORTION OF SAID ZONE, SAID GAS BEING PREHEATED TO AT LEAST 600*F., MAINTAINING A TEMPERATURE OF FROM ABOUT 600-1000*F. AND A PRESSURE OF FROM ABOUT 0.1 TO 760 MM. IN SAID ZONE COMBUSTING NO MORE THAN ABOUT 3% OF THE ADSORBED WAX BASED ON SAID FEED STREAM, WITHDRAWING A STREAM CONTAINING THE UNCOMBUSTED WAX PREVIOUSLY ADSORBED ON SIEVES, AND COOLING SAID ZONE.