Abstract:
A process for regenerating catalyst particles is disclosed. The process includes the steps: (a) withdrawing a regeneration zone effluent comprising halogen from a regeneration zone, wherein the regeneration zone contains catalyst particles comprising halogen; (b) contacting a first portion of the regeneration zone effluent with adsorbent in a first adsorption zone, removing halogen from the first portion of the regeneration zone effluent, and withdrawing from the first adsorption zone a first adsorption zone effluent; (c) contacting the first adsorption zone effluent with a water removing material to create a first water-depleted stream; and (d) passing the first water-depleted stream to the regeneration zone. Other embodiments include different orders of the steps.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from Provisional Application No. 62/093,506 filed Dec. 18, 2014, the contents of which are hereby incorporated by reference in its entirety. 
    
    
     The disclosure relates to a process for regenerating catalyst particles wherein a water removing material is used to remove moisture from one or more process streams. 
     BACKGROUND OF THE INVENTION 
     Numerous hydrocarbon conversion processes are widely used to alter the structure or properties of hydrocarbon streams. Such processes include isomerization from straight chain paraffinic or olefinic hydrocarbons to more highly branched hydrocarbons, dehydrogenation for producing olefinic or aromatic compounds, reforming to produce aromatics and motor fuels, alkylation to produce commodity chemicals and motor fuels, transalkylation, and others. 
     Many such processes use catalysts to promote hydrocarbon conversion reactions. These catalysts tend to deactivate for a variety of reasons, including the deposition of coke upon the catalyst, and/or loss of catalytic metal promoters such as halogens. Consequently, these catalysts are typically reactivated in a process called regeneration. Regeneration can include, among other things, removing coke from the catalyst by burning (combustion), and replenishing catalytic promoters such as halogens on the catalyst, and drying the catalyst. 
     One of the problems during regeneration of halogen-containing catalysts is the loss of halogen from the catalyst. This happens when catalyst particles are contacted with gases that, while regenerating the catalyst particles, tend also to remove halogen from the catalyst particles. Therefore, processes have been developed for returning a halogen to catalyst particles undergoing regeneration. For example, U.S. Pat. No. 6,881,391 discloses a method for regenerating catalyst particles wherein chlorine-containing vent gas from a catalyst regenerator is sent to an adsorption/desorption system to recover the chlorine, and the recovered chlorine is passed back to the catalyst regenerator. 
     Water can build up in the circulating gas, and if using a catalyst sensitive to moisture, then moisture reduction becomes desirable. 
     Therefore, what is needed is an improved process for the regeneration of halogen-containing catalysts wherein excess moisture can be removed from the process streams of the catalyst regeneration system. 
     SUMMARY OF THE INVENTION 
     The foregoing needs are met by a process for regenerating catalyst particles according to the invention. 
     It is an advantage of the invention to provide a catalyst regeneration system including a water removing material, such as a membrane, wherein water can be selectively rejected from the regeneration vent gas that leaves the regeneration zone and enters the burn zone. The membrane is very stable in the highly acidic environment and highly selective to reacting with and removing water. The HCl, Cl 2  and all other molecules are retained and can be sent to an adsorption/desorption system for recovery of chlorine. The process is improved by sending a dry gas to the adsorption zone. This reduces the build up of moisture in the burn zone of the catalyst regenerator of the regeneration zone. Other water removing materials may be used, and other forms of the materials may be used such as beads. 
     It is another advantage of the invention to provide a catalyst regeneration system including a water-removing material that dries the reduction gas that is used in the reduction zone of the system. Reducing the moisture in the reduction gas improves the reduction of the catalyst and leads to improved yields. 
     These and other features, aspects, and advantages of the present invention will become better understood upon consideration of the following detailed description, drawings and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a catalyst regeneration system including a stacked arrangement of reactors, a regenerator, and an adsorption zone for removing halogens from the regenerator vent gas and returning these halogens to the regenerator. 
         FIG. 2  illustrates the adsorption zone of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of one water removing zone of the arrangement of  FIG. 1  taken along line  3 - 3  of  FIG. 1 . 
         FIG. 4  is a cross-sectional view of the water removing zone of  FIG. 3  taken along line  4 - 4  of  FIG. 3 . 
     
    
    
     Like reference numerals will be used to refer to like parts from Figure to Figure in the following description of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a catalyst regeneration system  8  including a stacked arrangement of reactors, a regenerator in the regeneration zone, and an adsorption zone for removing halogens from the regenerator vent gas and returning these halogens to the regenerator. It is understood that the adsorption zone may be operated in a desorption mode as well, such as for desorbing adsorbed components. Line  10  supplies catalyst particles to a valve  12 . Hydrogen enters valve  12  through line  14  at a rate that regulates the transfer of catalyst particles through valve  12  into line  18 . As catalyst particles enter line  18 , more hydrogen enters the bottom of line  18  through line  16  and transports the catalyst particles upwardly through line  18  to the top  20  of stacked reactor arrangement  22 , which the particles and lift fluid enter. 
     Catalyst particles flow from the top to the bottom of the stacked reactor arrangement  22 . At the top  20 , the catalyst particles pass first through a reduction zone, where hydrogen gas reduces the metal on the catalyst particles. From there the catalyst particles pass through multiple reactors where hydrocarbons contact the catalyst particles and coke is deposited on the catalyst particles. The stacked reactor arrangement  22  permits continuous or intermittent flow of the catalyst particles from the top  20  to lower retention chamber  24  at the bottom. Additional hydrogen enters chamber  24  through a line (not shown) at a rate that purges hydrocarbons from the catalyst particles in chamber  24 . 
     Catalyst particles containing coke deposits flow from chamber  24  and through line  26 . In line  26 , hydrogen and hydrocarbons are displaced from the catalyst particles to prevent any carry-over of hydrogen and hydrocarbons to regenerator  40 . At the bottom of line  26 , a valve  28  transfers catalyst particles upwardly through line  34 . Nitrogen enters valve  28  through line  30  and additional nitrogen enters the bottom of line  34  through line  32 . 
     Catalyst particles pass through line  34  into disengager  36 . Nitrogen enters disengager  36  through a line (not shown) at a rate that separates broken or chipped catalyst particles and catalyst fines from the whole catalyst particles. The catalyst chips and fines exit through another line (not shown) for collection. The whole catalyst particles flow from the bottom of disengager  36  through lines  38  to regenerator  40 . 
     Lines  38  discharge catalyst particles into conduits  42  inside regenerator  40 . Conduits  42  feed the catalyst particles to annular regeneration zone  48  formed by outer catalyst particle retention screen  46  and inner catalyst particle retention screen  52 . Bed  48  is in a coke combustion zone  50 . In this embodiment, regenerator  40  is cylindrical in form, as are retention screens  46  and  52 , which are concentric with regenerator  40 . Screens  46  and  52  are perforated with holes that are large enough to allow gas to pass through bed  48  but do not permit the passage of catalyst particles therethrough. Outer screen  46  extends downward from lines  42  and is supported at its bottom and its top to keep it centered in regenerator  40 . Inner screen  52  is attached to the top head of regenerator  40  and extends downward from there to a point slightly above the lower end of the screen  46 . The bottom of inner screen  52  is open to allow gas containing oxygen and chlorine to flow upward from cylindrical regeneration zone  58  to central section  54 , as will be described hereinafter. 
     The bottom of bed  48  is open to allow catalyst particles to empty from bed  48  into bed  58 . The catalyst particles in bed  58  are located in a chlorination zone  60 . Bed  58  is defined in part by annular baffle  56 . Catalyst particles flow from bed  58  into the open volume between truncated conical baffle  72  and conical baffle  68 , which is concentric with baffle  72 . From there, the catalyst particles flow downwardly into an annular holdup zone  76  defined by a lower cylindrical portion  74  of baffle  72  and a lower cylindrical portion of baffle  68 . The annular volume of catalyst particles retained between baffles  72  and  68  provides a gas seal to limit the flow of gases upwardly through the catalyst particles into bed  58 . Catalyst particles flow from zone  76  into cylindrical regeneration zone  84 . The catalyst particles in bed  84  are located in a drying zone  80 . Bed  84  is defined in part by annular baffle  79 . The catalyst particles are periodically transferred from bed  84  by withdrawing a predetermined volume of catalyst through line  102  which in turn allows the catalyst particles to slump downward through the packed catalyst beds in disengager  36  and in zones  50 ,  60 , and  80 . 
     The catalyst particles exiting regenerator  40  through line  102  pass to nitrogen seal drum  104 , through line  106 , and to lock hopper arrangement  108 . Seal drum  104  and lock hopper arrangement  108  control the transfer of catalyst particles back to stacked reactor arrangement  22 . The nitrogen seal drum  104  and lock hopper arrangement  108  also displace oxygen gas from the catalyst particles to prevent any carry-over of oxygen to stacked reactor arrangement  22 . 
     Looking now to the gas flows, recycle gas enters the coke combustion zone  50  through line  100 . The recycle gas is distributed in annular chamber  44  that extends around screen  46  and is defined by screen  46  and the vessel wall of regenerator  40 . An upper portion of screen  52  is impermeable to gas flow, or blanked off, to prevent gas flow from chamber  44  across the top of the regenerator  40 . As the recycle gas passes through regeneration zone  48 , oxygen is consumed in the combustion of coke and gas is collected in section  54 . The process of combusting coke removes chloride from the catalyst particles, and therefore the gas collected in section  54  contains not only water and carbon dioxide but also chlorine and hydrogen chloride. 
     The gas that collects in section  54  includes not only gas from bed  48 , but also gas containing oxygen, chlorine, and hydrogen chloride flowing upward from bed  58 . Because the gas that collects in section  54  includes gas that will be vented from the coke combustion zone  50  as well as gas that will be recycled in the coke combustion zone  50 , the gas is usually denoted “vent gas/recycle gas”. The vent gas/recycle gas leaves section  54  and passes through line  86 . to cooler  88 . Cooler  88  uses any suitable cooling medium such as water or air, and removes some of the heat from the vent gas/recycle gas during normal operation. The cooled vent gas/recycle gas flows through line  90  and splits into two portions. One portion is recycled to the coke combustion zone  50  and is called the recycle gas stream. This portion is conveyed by line  92  to blower  94  and then passes through line  96  to heater  98 . Heater  98  heats the recycle gas stream to carbon-burning temperatures during start-up and to a lesser degree adds heat to the recycle gas stream during normal operation. Heater  98  operates in conjunction with cooler  88  to regulate the heat content of the recycle gas stream. The recycle gas stream passes through line  100  and enters coke combustion zone  50 . 
     The other remaining portion of the cooled regeneration vent gas stream is called the regeneration vent gas and flows through line  110  to cooler  114 . Cooler  114  cools the regeneration vent gas stream by indirect heat exchange with any suitable cooling medium such as water or air. The cooled regeneration vent gas flows through line  116  to pressure regulating valve  118 . Pressure indicator-controller  112  measures the pressure in line  110  and generates signal  120 . Signal  120  is representative of the difference between the actual pressure and the desired pressure in line  110 . Signal  120  regulates the extent of opening of valve  118 . The desired pressure in line  110  is set in order to maintain a target pressure in one of the zones of the regenerator  40 , usually the coke combustion zone  50 . After being cooled and depressured, the regeneration vent gas stream is at the desired gas inlet temperature for adsorption and flows through line  122  to adsorption zone  123 . 
     A better understanding of adsorption zone  123  can be obtained from  FIG. 2 . Zone  123  comprises two beds  150  and  152  and the other lines, the valves, and the other equipment shown in  FIG. 2 . Beds  150  and  152  contain an adsorbent such as alumina. When bed  150  operates in adsorption mode, bed  152  operates in desorption mode. The regeneration vent gas stream in line  122  flows through line  124 , valve  128 , line  132 , and line  146 , and enters bed  150 . The adsorbent in bed  150  adsorbs at least some of the chlorine and hydrogen chloride from the vent gas. The adsorption effluent gas flows through line  154 , valve  158 , and line  162 , and the effluent is discharged from zone  123  through line  166 . If desired, this effluent can be sent to conventional facilities (not shown) to neutralize any residual chlorine or hydrogen chloride that may be present in the effluent. However, the residual chlorine and hydrogen chloride content is so relatively low that the need for such an additional neutralization step is often eliminated. 
     Looking at  FIG. 1 , line  232  supplies makeup air to coke combustion zone  50 . This makeup air is introduced, however, initially to drying zone  80 , from which most of the oxygen in the makeup air ultimately makes its way to coke combustion zone  50 . Air from line  232  is added to regenerator  40  at a rate of addition generally equal to the rate of vent gas in line  110 . Air in line  232  is dried in drier  234  and then passes through line  236  to heater  238 , which raises the temperature of the air stream to about 566° C. (1050° F.). The heated, dry air stream passes through line  240  to drying zone  80 . The air stream enters annular space  82 , which is defined by annular baffle  79  and the vessel wall of regenerator  40 . Annular baffle  79  is used to uniformly distribute the air through bed  84 . Contacting the catalyst in bed  84  with the heated, dry air removes water from the catalyst. 
     Drying bed effluent gas, which is mostly air now laden with water, exits the top of bed  84 . Pressure drop provided by zone  76  forces the majority of the upward flowing gas into annular space  78 , which is defined by the vessel wall of regenerator  40 , baffles  72  and  74 , and partition  70 . Most of the water-laden effluent gas flows through line  168  to zone  123  to be used for desorption. Referring to  FIG. 2 , the gas in line  168  flows through line  170 , line  192 , valve  196 , and line  200 , and enters bed  152 . The adsorbent in bed  152  contains chloride, which is desorbed and exits as hydrogen chloride and chlorine with the effluent of bed  152 . A portion of the gas flowing through line  200  may be made to bypass bed  152  through a bypass line (not shown). Bed  152  effluent flows through line  204 , line  208 , valve  212 , line  216 , line  218 , and line  226  to heater  228  (see  FIG. 1 ). Heater  228  heats the gas to the desired gas inlet temperature, and the gas flows through line  230  and enters chlorination zone  60 . Flow indicator  220  measures the flow rate of the effluent in line  218 , and analyzer  222  measures the concentrations of chlorine and hydrogen chloride in the effluent in line  218 . These measurements of flow rate and concentrations allow computation of the quantities of chlorine and hydrogen chloride per unit time carried by the bed  152  effluent to chlorination zone  60 . If the rate of chlorine or hydrogen chloride is too low for the requirements of the chlorination zone  60 , additional chlorine-containing materials such as a chlorinated paraffin can be added to line  218  through line  224 . 
     The gas that contacts the catalyst in bed  58  comprises a mixture of gas flowing through line  230  and gas flowing upward from annular space  78 . This mixture is formed in a two-pass baffle system  69  before entering the bottom of bed  58 . Partition  70  is a flat plate, which may be solid and impermeable to gas flow or alternatively may define a plurality of restriction orifices that allow gas to flow through partition  70 . When present, the restriction orifices are sized to produce a pressure drop for flow passing through partition  70 . The pressure drop induces most of the gas flow from space  78  to flow through zone  123  and to enter space  62  via line  230 . When the restriction orifices are not present, partition  70  functions as a barrier to gas flow, forcing even more of the gas flow out to zone  123 . If needed, a compressor or blower (not shown) can be placed anywhere in line  168 , zone  123 , line  218 , or line  226  to force this gas flow through zone  123 . When the restriction orifices are present, the remainder of the gas flow from space  78  enters space  62  through partition  70 . If the pressure drop is suitable, the previously mentioned chlorine-containing materials added into line  218  through line  224  may instead be introduced directly into space  62 . Space  62  is defined by upper cylindrical portion  66  of baffle  72 , partition  70 , baffle  56 , and the vessel wall of regenerator  40 . Cylindrical portion  66  is concentric with annular baffle  56 . From space  62  the mixture of gases flows into space  64  defined by cylindrical portion  66  and annular baffle  56 . From space  64 , the gases enter the bottom of bed  58 . 
     Prior to being placed in adsorption mode, bed  150  operated in desorption mode. While bed  150  was in desorption mode, the chloride on the adsorbent was desorbed and passed to chlorination zone  60  through line  218 . This desorption depleted the adsorbent in bed  150  of chloride, and thereby prepared the adsorbent in bed  150  for use in adsorption mode.  FIG. 2  provides an understanding of how bed  150  operated in desorption mode. The gas in line  168  flowed through line  190 , valve  194 , and line  198 , and entered bed  150 . The adsorbent in bed  150  contained chloride, which was desorbed and exited with the effluent of bed  150 . Bed  150  effluent flowed through line  202 , line  206 , valve  210 , and line  214 , and into line  218 . 
     Conversely, prior to being placed in desorption mode bed  152  operated in adsorption mode. While bed  152  was in adsorption mode, the chlorine and hydrogen chloride from the vent gas stream were adsorbed on the adsorbent. This adsorption added chloride to the adsorbent in bed  152 , and thereby prepared the adsorbent in bed  152  for use in desorption mode. When bed  152  was in adsorption mode, the vent gas stream in line  122  flowed through line  126 , valve  130 , line  134 , and line  148 , and entered bed  152 . The adsorbent in bed  152  adsorbed some of the chlorine and hydrogen chloride from the vent gas. The adsorption effluent gas flowed through line  156 , valve  160 , and line  164 , before being discharged through line  166 . 
     If the pressure used for removing halogen from the vent gas stream is less than the pressure used for removing halogen from the adsorbent, then a bed that has been used for removing halogen from the vent gas stream should be pressured up to prior to removing halogen from the bed. A convenient gas source for this pressuring step is the gas that is being used for removing halogen from the bed. In the case of pressuring bed  152 , valve  184  is opened so that this gas may flow from line  168 , through lines  170  and  172 , through restriction orifice  174 , through lines  176  and  180 , through valve  184 , through lines  188  and  204 , and into bed  152 . In the case of pressuring bed  150 , valve  182  is opened so that the gas flows from line  168 , through lines  170  and  172 , through orifice  174 , through lines  176  and  178 , through valve  182 , through lines  186  and  202 , and into bed  150 . Orifice  174  is sized to set a gas flow rate corresponding to a desired pressuring rate. 
     After halogen has been removed from an adsorbent bed, and if the pressure used for removing halogen from the vent gas stream is less than the pressure for removing halogen from the adsorbent bed, that adsorbent bed should be depressured prior to being placed in adsorption mode. A convenient destination for the gas released during depressuring is a bed that is being used for adsorption, since the released gas may contain halogen. In the case of depressuring bed  150 , valve  140  is opened so that gas flows from bed  150 , through lines  146  and  136 , through valve  140 , through line  144 , through restriction orifice  142 , through lines  138  and  148 , and into bed  152 . In the case of depressuring bed  152 , valve  140  is opened so that gas flows from bed  152 , through lines  148  and  138 , through orifice  142 , through line  144 , through valve  140 , through lines  136  and  146 , and into bed  150 . Orifice  142  is sized to set a gas flow rate corresponding to a desired depressuring rate. 
     Halogen recovery is generally greater than about 80 wt-% and preferably greater than about 90 wt-%. The vent gas stream that enters the bed being used for adsorption typically contains from 50 to 10000 mol-ppm hydrogen chloride and from 1 to 500 mol-ppm chlorine. The vent gas stream enters cooler  114  at typical catalyst regeneration temperatures of from about 371° C. to about 538° C. (700° F. to 1000° F.). Most of the cooling occurs in cooler  114  but some additional cooling may occur as a result of depressuring the vent gas stream across valve  118 . The inlet temperature of the gas entering a bed in adsorption mode is typically at from about 149° C. to about 260° C. (300° F. to 500° F.). If the temperature of the adsorbent in a bed that is placed in adsorption mode is initially different from the inlet temperature of the gas, the adsorbent temperature will rise or fall. Therefore, after some period of contacting the temperature at which adsorption occurs will usually be within the range of from about 149° C. to about 260° C. (300° F. to 500° F.). 
     The regeneration zone and the adsorption zone may be in immediate proximity to one another, or the regeneration zone and the adsorption zone may be spaced apart from one another. The distance between the regeneration zone and adsorption zone may require conduits to conduct streams between the two zones and the two zones may be spaced apart by a distance of from 20 meters to 1000 meters or more. By the term “spaced apart,” it is intended that the adsorption zone be a separate structure from the regeneration zone that is separated from the regeneration zone by a distance, except for connecting lines such as the regeneration vent gas line or other lines. In an example process, the regeneration zone is disposed within a regeneration zone vessel, and the adsorption zone is disposed within an adsorption vessel that is separate from the vessel of the regeneration zone. The adsorption vessel can include, for example, a separate stack of modules that are shop fabricated. This allows improved quality control, and reduces or eliminates modification to existing equipment such as the regeneration zone. 
     Turning now to  FIGS. 1, 3 and 4 , the catalyst regeneration system  8  includes moisture removal zones  310 ,  320 ,  330 ,  340 , and  350 . The moisture removal zone  310  is located in line  96  in order to remove water from the recycle gas stream that is fed back into the coke combustion zone  50 . The moisture removal zone  320  is located in line  122  in order to remove water from the vent gas stream that is fed into the adsorption/desorption zone  123 . The moisture removal zone  330  is located in line  218  in order to remove water from the stream from the adsorption/desorption zone  123  that is fed back into the chlorination zone  60 . The moisture removal zone  340  is located in line  232  in order to remove water from the makeup air that is supplied to the coke combustion zone  50 . The moisture removal zone  350  is located in line  16  in order to remove water from the hydrogen that enters the reduction zone of the stacked reactor arrangement  22 . 
     Referring now to  FIGS. 3 and 4 , the moisture removal zone  320  is shown in greater detail. The moisture removal zone  320  includes a housing formed by opposed spaced apart transverse walls  410  and  411  that extend between a cylindrical outer wall  412 . Cylindrical tubes  326  extend between the walls  410  and  411 . The tubes  326  each include a hollow interior space  327  defined by an inner surface  328 . The tubes  326  also include an outer surface  329 . Any number of tubes  326  can be arranged between the walls  410  and  411 . Process fluid F from line  122  flows through the interior space  327  of each tube  326  as shown in  FIG. 4 . 
     The wall  325  of each of the cylindrical tubes  326  comprises a material that is selectively permeable to water. In one non-limiting example, the material of the walls  325  of each of the cylindrical tubes  326  removes gases based on their chemical affinity for sulfonic acid groups. Sulfonic acid groups have a very high affinity for water, so sulfonic acid groups absorb water from the process fluid F into the wall material at the inner surface  328  of each wall  325 . Once absorbed into the wall  325 , the water permeates from the inner surface  327 , one sulfonic group to another until the water reaches the outside surface  329  of the tubes  326 , where it evaporates into the surrounding gas in the housing formed by the transverse walls  410  and  411  and the cylindrical outer wall  412 . 
     If the gases inside the tubes  326  contain more water (have a higher water vapor pressure) than the gases outside the tubes  326 , the water vapor will move out of the tubes  326 . If the gases outside of the tubes  326  contain more water, water vapor will move in. Therefore, a hot dry purge gas flow P (see  FIG. 4 ) is moved over the tubes  326  to remove water from the interior space of the housing. The dry purge gas flow P is a heated, dry air stream from heater  238  that passes through lines  306 ,  308  and into line  322 . After passing through the interior space of the housing and removing water, the purge gas is vented through line  323 . Suitable valves may be provided in lines  322  and  323  to control purge gas pressure levels. 
     In one non-limiting example embodiment, the water removing material of the walls  325  of each of the cylindrical tubes  326  comprises a polymeric backbone with sulfonic acid groups. Preferably, the water removing material comprises a fluorocarbon having sulfonic acid groups. Most preferably, the water removing material comprises tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer, which is sold under the trademark Nafion®. The water removing material of the walls  325  of each of the cylindrical tubes  326  acts as a semi-permeable membrane that allows water molecules to pass through the material but other molecules are retained in the process fluid stream in line  122 . 
     The other moisture removal zones  310 ,  330 ,  340 , and  350  can be of a similar construction to the moisture removal zone  320  and therefore, the moisture removal zones  310 ,  330 ,  340 , and  350  will not be described in further detail. Looking at  FIG. 1 , the moisture removal zone  310  receives dry purge gas flow P as a heated, dry air stream from heater  238  that passes through lines  306 ,  308  and into line  312 . After passing through the interior space of the housing of the moisture removal zone  310 , the purge gas is vented through line  313 . Likewise, the moisture removal zone  330  receives dry purge gas flow P as a heated, dry air stream from heater  238  that passes through lines  306 ,  308  and into line  332 . After passing through the interior space of the housing of the moisture removal zone  330 , the purge gas is vented through line  333 . Likewise, the moisture removal zone  340  receives dry purge gas flow P as a heated, dry air stream from heater  238  that passes through line  306  and into line  342 . After passing through the interior space of the housing of the moisture removal zone  340 , the purge gas is vented through line  343 . Likewise, the moisture removal zone  350  receives dry purge gas flow P as a heated, dry air stream from heater  238  that passes through line  306  and into line  352 . After passing through the interior space of the housing of the moisture removal zone  350 , the purge gas is vented through line  353 . 
     Reducing the moisture in the process flow streams of the catalyst regeneration system  8  using any combination of one, two, three, four, or five of the moisture removal zones  310 ,  320 ,  330 ,  340 ,  350  improves the reduction of the catalyst and reduces the build up of moisture in the burn zone of the catalyst regenerator, thereby improving yields. 
     In another embodiment, the material that is selectively permeable to water may be used in form of beads. For example, the water removing material that comprises tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer, which is sold under the trademark Nafion® may be in the form of beads. The beads may be housed in one or more vessels, and in one embodiment the beads are housed into dual vessels with one vessel in active drying mode while the other vessel is being regenerated. When the water uptake capacity of the beads in the vessel in active drying mode has been reached, or before capacity has been reached, the vessel is switched to the regeneration mode, and the vessel that had been in regeneration mode is switched to active drying mode. The beads may be regenerated by drying with a hot dry gas stream such as hot dry air or hot dry nitrogen. For regeneration, the hot drying gas may be passed over the beads in an up-flow or in a down-flow mode. Regenerant may be flushed from the vessel before being placed in service. An advantage of this embodiment is a continuous dry stream recycled to the continuous catalyst regeneration system without significant swings in flow rate. The moisture removal zones having moisture removal material in bead form may be located in any of the locations described above. Combinations of moisture removal zones in membrane form, bead form, and tubular form may be employed. It is also envisioned that a moisture removal zone may be located prior to the adsorption zone. 
     Although the invention has been described in considerable detail with reference to certain embodiments, one skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which have been presented for purposes of illustration and not of limitation. Therefore, the scope of the appended claims should not be limited to the description of the embodiments contained herein.