Low cost high yield Iso-octene/ Isooctane process with capability to revamp the MTBE units

Abstract

This invention covers a process for dimerizing of isobutylene to Iso-octene and unique configuration is being disclosed, where the Feed is diluted to low level with recycle which has essentially no Iso-octene, dual catalyst system, new selectivator (IPA) and successive catalyst stages if needed to enhance the conversion. The process is very selective and provides higher isobutylene conversion. Additionally the invention also covers the hydrogenation of olefins to Paraffin, Iso-octene to Iso-octane product under moderate conditions and with dual or single catalyst system.

1 . A Process for producing Iso-octene Comprising:
 A) Dimerizing the isobutylene in the FC C, Steam Cracker, Thermal Cracker or on purpose dehydrogenation streams, in the presence of sulfonated resin catalyst Amberlyst 15, 35 or 36 or equivalent at moderate temperatures as defined in the process invention. The process uses a top bed of catalyst which is for selective hydrogenation e.g. Palladium, Nickel, Resin doped Palladium, Nickel/Mo, Co/Mo. Ni/W or Pd/Pt etc. but not limited to, so as perform selective hydrogenation of dioolefins in the Feed, followed by normal resin catalysts Amberlyst 15, 35, 35 or equivalent. The WHSV is 5 to 15 for first catalyst bed, which is hydrogenation catalyst, and 3 to 6 for the resin catalyst, on fresh Feed basis. The temperature is in the range of 100 to 160 F, and pressure is 100 to 175 psig at the reactor inlet.   B) Taking total sidedraws or partial sidedraws from the debutanizer after the Iso-octene and heavy's have gone down the column, and recycling it to the Ist Reactor to reduce the concentration of the isobutylene in the reactor. This recycle reduces the isobutylene concentration to half to one fifth compared to fresh Feed isobutylene concentration.   C) Providing small amount of propylene in the feed so that it is hydrated and makes Isopropyl alcohol (IPA), which is used as solvator/Selectivator to enhance the catalyst activity. This is recycled in the system with the C 4  stream so as to make very small amount of IPA.   D) To enhance the conversion part of the recycle stream is sent to the side Reactor which enhances the conversion and selectivity. It is claimed that the liquid is returned at the same location from where the sidedraw was taken or at a suitable location, so as to have no effect on size of the debutanizer column design.   E) The special art in the configuration is being used in the process so as to recycle sidedraw's which provide the dilution an some of unconverted isobutylene is recycled in turn, new selectivator (IPA) to get the best results in conversion to solvate the catalyst, yield and selectivity. The configuration is also invented to install bulk catalyst in the column by installing Johnson Screens in the column, so the catalyst and holddown grid with Johnson screen to secure the catalyst at the top of the bed. This allows easy revamp of the existing reactive distillation applications, but are cumbersome to install catalyst and the cost is higher than the catalyst from the vendor. The art of by passing the vapor with chimney trays or external pipes is being used as these reaction are taking place in liquid phase (vapor does not contribute to the reaction). Multiple beds can be used.   F) Either sidedraw from the debutanizer can be used to take IPA with C 4  stream, or the IPA together with iso-octene can be sent to another column or existing alcohol recovery column. The existing alcohol recovery column or the Iso-octene column, can be used for the separation of IPA, and is recycled whereas Iso-octene sent to OSBL after cooling or can be sent to Iso-octane unit without cooling as required. The C 4  sidedraw are still taken from the debutanizer column for dilution for the 1 st reactor and also feed to the side reactor.   G) This invention also covers the dimerization of iso-amylene to produce Di-isoamylene. RHT process provides selectively, similar to Iso-octene process.   H) Normal precautions are taken for removing the poison from the Feed by either water wash or adsorbent media.   
   
   
       2 . The method of  claim 1 ,
 A) Where as in the art of this invention uses dual catalyst system. The first bed at the top, in the 1 st reactor is a trifunctional catalyst (sulfonated Resin catalyst doped in Palladium e.g. Amberlyst CH10 or Levatit K 2624) or Palladium or Nickel catalyst so as to selectively hydrogenate the diolefins and stabilize the olefins, which enhances the catalyst life. This is done at very high space velocity so as to keep the catalyst cost low. The selective hydrogenationeither in the iso-octene unit or upstream is exclusively being claimed by RHT Iso-octene process and one of the major claims for this application.   B) Hydrogen is expected to be close to stiochiometric for diolefin selective hydrogenation in the reactor, as the intention is to see that all the hydrogen is consumed and no olefins are saturated.   C) The process claims the highest yield, low n-butylene loss to codimers, high selectivity and enhanced catalyst life due to dual catalyst bed and also using a better selectivator (IPA) and low isobutylene concentration due to dilution by recycle.   
   
   
       3 . The process is designed to hydrogenate the Iso-octene to Iso-octane:
 A) The method of  claim 3 , the invention uses the art so as to have milder conditions and using two stage approach for hydrogenation of olefins to paraffins, by using, Nickel Catalyst (or Nickel/Molybdenum, Nickel/Tungsten, Palladium, Palladium/Platinum) in the 1st Reactor with excess hydrogen than stoichiometric. Reactor effluent is flashed, the liquid after the flash from first reactor, is recycled to first reactor as heat sink (after cooling to remove the heat of reaction) and part of this liquid is forward feed to the Finishing Reactor which could have either Palladium Catalyst (Palladium/Platinum or Nickel catalyst similar to in the 1st reactor). The invention claims 99% hydrogenation of olefins to paraffins.   B) The method of  claim 3 , Where 1st Reactor operates at inlet pressure of 250 psig to 450 psig (preferably closer to 250 psig) and temperature of 200 to 350 F (preferably 260 F), and recycle liquid is provided after the flash as shown in  FIG. 6 , as a heat sink so as to have temperature rise in the reactor of 50 to 150 F (preferably 100 F). Part of the flashed liquid after 70 to 90% hydrogenation in the 1st Reactor, is sent to the finishing reactor to complete the olefin hydrogenation to Paraffin to 99%.   C) The method of  claim 3 , where WHSV in the 1st Reactor is kept in the range 1 to 4 (closer to 2) based on fresh Feed basis, Finishing Reactor WHSV is 2 to 4 (closer to 2). The  FIG. 6  shows the detail of this configuration.   D) The method of  claim 3 , where the hydrogen is 1.2 to 2.0 times (closer to 1.4 times) the stoichiometric required for olefin saturation to Paraffin. The Reactor is designed to operate in single phase or two-phase operation, which ever is most cost effective.