Process and structure for effecting catalytic reactions in distillation structure

A concurrent catalytic reaction with distillation structure involves a plurality of vapor permeable plates which are arranged in spaced apart relationship with a catalyst placed in the open space between two adjacent plates. The catalyst filled area presents a reaction zone where catalytic reaction can take place and the vapor permeable plates present a large surface area for vapor and liquid phase exchange. The invention also encompasses a process for concurrent catalytic reaction with distillation employing structure as aforedescribed and including the steps of feeding a liquid stream to a column employing such structure and directing the stream through the catalytic reaction zone while concurrently distilling a portion of the liquid to present a vapor stream which is directed in countercurrent relationship to the liquid stream flow.

BACKGROUND OF THE INVENTION 
This invention relates in general to a mass transfer or distillation column 
and, more particularly, to a structure within the column for concurrently 
contacting a fluid stream with a particulate solid catalyst while 
distilling the reaction product. 
The use of a catalyst packed distillation column allows concurrent 
catalytic reaction of a fluid stream flowing through the catalyst and 
fractionation of the resulting reaction product. The use of solid, 
particulate catalysts in a conventional fixed bed within such columns 
generally results in high pressure drop within the column as the low 
permeability of the catalyst bed impedes the upward flowing vapor and 
downward flowing liquid. Compaction and breakage of the catalyst in 
conventional fixed beds inevitably occurs and may further increase the 
pressure drop or may result in preferential channeling of the fluid 
streams through areas of high permeability. Portions of the catalyst bed 
having low permeability are then segregated from the fluid streams and the 
efficiency of the reaction process is reduced. 
In an attempt to reduce the high pressure drop and channeling which may 
occur within the compact catalyst fixed bed, the particulate catalyst in 
some columns has been placed into a plurality of pockets within a cloth 
belt. The belt is then supported by a specially designed support structure 
such as an open mesh knitted stainless steel wire joined with the cloth 
belt. U.S. Pat. No. 4,242,530 provides an example of one such structure. 
While these types of reaction with distillation structures may provide 
reduced pressure drop and reduced- channeling within the distillation 
column, they often fail to achieve the distillation performance obtainable 
with many types of structured packings. Moreover, because the catalyst 
containers are intimately associated with the support structure, both the 
catalyst containers and support structure must be dismantled and replaced 
when the catalyst is spent. This can be a frequent occurrence when 
catalysts which have a cycle life as short as several months are used and 
results in significant losses in operating time. 
Structured packings are also well known in the art including packings made 
of sheet material and having configurations for promoting vapor liquid 
contact. A particularly advantageous structured packing is that shown in 
U.S. Pat. No. 4,296,050. It has not heretofore been known to combine a 
structured packing of the type shown in the referenced patent with a fixed 
catalyst bed in a column where distillation and reaction occur 
simultaneously. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a method for concurrently 
catalytically reacting and distilling fluid streams within a column in a 
manner which allows for improved distillation performance. 
It is also an object of this invention to provide a method for utilizing 
structured packing within a distillation or mass transfer column in 
combination with an associated catalyst to allow concurrent catalytic 
reaction and distillation of fluid streams flowing through the column. 
It is a further object of this invention to provide a structure within a 
distillation or mass transfer column which allows concurrent catalytic 
reaction with distillation of fluid streams flowing through the structure 
and which allows structured packing to be utilized for greater 
distillation efficiency. 
It is another object of this invention to provide a structure within a 
column which allows concurrent catalytic reaction with distillation of 
fluid streams and which allows for reuse of the support structure after 
the catalyst is spent and removed. 
It is yet another object of this invention to provide a structure within a 
distillation or mass transfer column which allows concurrent catalytic 
reaction with distillation of fluid streams and which allows for selective 
installation of the catalyst so that pressure drop through the 
distillation column may be varied. 
To accomplish these and other related objects of the invention, a 
distillation or mass transfer column is provided with a structure 
comprising a plurality of corrugated plates and an associated permeable 
catalyst bed. The corrugated plates are arranged in parallel relationship 
and present open channels between the plates for the distribution and 
fractional distillation of fluid streams. The catalyst bed is maintained 
in at least a portion of the open channels to provide a catalytic reaction 
zone. In one embodiment of the invention, the catalyst bed is formed by 
sandwiching a layer of solid, particulate catalyst between pairs of 
plates. In other embodiments of the invention, the catalyst bed fills at 
least a portion of the corrugations on one side of the plates and is 
maintained in association with the plate by a permeable wall member which 
is coupled to the plate. 
In still another embodiment of the invention, the structure comprises a 
pair of plates constructed of vapor permeable material with pockets 
configured into the plates and interconnected with one another by 
passages. The area between the passages and the pockets are joined to one 
another by welding so as to add rigidity and strength to the structure. 
Catalyst is inserted within the pockets and passageways formed by the two 
plates. 
The rigid plates formed as above described are arranged in a structured 
fashion to provide uniform liquid distribution and increased distillation 
performance. The plates also serve as a support structure for the catalyst 
bed which forms a reaction zone in at least a portion of the open areas 
between the two plates. Use of the catalyst bed in conjunction with the 
plates allows for concurrent catalytic reaction of fluid streams with 
distillation of the reaction product.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings in greater detail and initially to FIGS. 1-4, 
one embodiment of a reaction with distillation structure is represented 
broadly by the numeral 10. Structure 10 is shaped for placement within a 
cylindrical mass transfer column 12 to allow concurrent catalytic reaction 
of fluid streams and distillation of the reaction products. Although 
illustrated as being generally cylindrical in shape, structure 10 may 
comprise other shapes as needed for large diameter columns or for 
application with columns of noncylindrical configurations. 
Reaction with distillation structure 10 comprises a plurality of pairs of 
corrugated plates 14 and 16 which are coupled together at their peripheral 
edges and maintained with their corrugations in parallel alignment. Each 
plate has alternating ridges 18 and troughs 20 which extend in parallel 
relationship and are formed by bending the plate or other suitable 
techniques. Ridges 18 in each plate are preferably of the same amplitude 
so that they lie in a common plane. Similarly, troughs 20 are preferably 
of the same amplitude and are co-planar. 
Corrugated plates 14 and 16 are formed from vapor and liquid permeable 
material having sufficient rigidity to maintain the desired corrugated 
configuration. Preferably, the plates comprise a wire gauze or metal 
screen material but other types of material such as plastic gauze and 
ceramics which have the desired characteristics may also be utilized. 
As best shown in FIGS. 3-4, a catalyst bed 22 is sandwiched between each 
associated pair of corrugated plates 14 and 16 with the plates forming an 
enclosing envelope for the catalyst bed. The catalyst bed 22 may comprise 
any solid particulate catalyst 24 which is suitable for the applicable 
reaction occurring within the catalyst bed. Catalyst 24 may be an acid or 
basic catalyst or may comprise catalytic metals and their oxides, halides 
or other chemically reacted states. Molecular sieves may also be utilized 
as the catalyst. The catalyst chosen should be heterogeneous with the 
system reaction and the fluid streams. By way of example, acid cation 
exchange resins may be used for dimerization, polymerization, 
etherification, esterification, isomerization, and alkylation reactions. 
Other catalysts such as molecular sieves, magnesia, chromia, silica, and 
alumina may be used for isomerization reactions. 
The catalyst particles 24 preferably are either a cylindrically shaped 
extrudate or in the form of small beads or the like. Irregular shaped 
granules or fragments may also be used. The size of the catalyst particles 
may be varied depending upon the requirements of the particular 
applications. 
The catalyst bed 22 is formed to a pre-selected uniform thickness between 
the parallel pairs of plates 14 and 16. The spacing between the plates is 
maintained by appropriate spacers 26 located at selected positions and 
tack welded to at least one of each pair of associated plates. The 
peripheral edges of the plates are sealed together in a suitable manner to 
maintain the catalyst particles in place. Sealing may be effected by 
securing one or more elongated sealing members such as solid rods 28 along 
the entire periphery of both plates and spanning the opening therebetween. 
Each rod member 28 is preferably rigid to help maintain the shape of 
plates 14 and 16 while sealing the ends of the area between the plates. 
The rods are held in rigid relationship to plates 14 and 16 by welding. 
A plurality of pairs of the appropriately sized plates 14 and 16 with an 
associated catalyst bed are placed upright on edge and arranged in facing 
relationship to form the generally cylindrical structure 10. A band 30 may 
be used to maintain the plates in the desired configuration. As is 
apparent from viewing FIGS. 1 and 2, each pair of plates contacts at least 
one adjoining pair to present a row of contiguous pairs of plates. The 
pairs of plates are oriented so that the ridges 18 and troughs 20 of each 
pair of plates are disposed at an angle and in criss-crossing relationship 
to the ridges and troughs of each adjacent pair of plates. Continuous open 
channels 32 are thus formed along the troughs between adjacent facing 
plates to facilitate liquid and vapor passage through the column. It is 
preferred that the ridges of the plates also extend at an angle to the 
vertical axis of the column 12 so that fluid streams flow along the 
channels at angles to the vertical axis of the column. This feature is 
best illustrated in FIG. 2 where the slanted lines on the upper and lower 
tower sections represent the ridges of the plates. 
The structure 10 operates as a structured packing for fractional 
distillation of fluid streams and concurrently provides for catalytic 
reaction of the fluid streams. In a typical installation, a plurality of 
structures 10 are stacked one on top of the other inside the column on an 
appropriate support structure. Each vertical row of structures is placed 
with its plates 14 and 16 parallel to other plates in the same row and at 
90.degree. relative to the plane of the plates in a vertically adjacent 
row. This relative orientation of three vertically spaced rows of plates 
is illustrated in FIG. 2. The structure 10 has particular applicability 
with liquid phase reactions having products separable by distillation and 
counter current gas/liquid contacting in liquid phase heterogeneous 
catalyst systems. In operation, one or more fluid streams are charged to 
the column 12 with liquid descending through structure 10 and vapor 
streams ascending through the structure. The liquid stream flow occurs in 
channels 32 along the surface of plates 14 and 16 and through the catalyst 
bed 22. Liquid distributors may be utilized at the upper end of structure 
10 to preferentially direct the liquid streams as desired into either the 
channels 32 or catalyst bed 22. 
The catalyst bed 22 forms a catalytic reaction zone for catalytically 
reacting the descending liquid streams. Concurrently, a vapor phase is 
formed by fractional distillation of the liquid streams and preferentially 
flows upwardly through channels 32 for mixing with descending liquid 
streams. Mass transfer between the liquid and vapor phases occurs 
primarily on the surfaces of the plates 14 and 16 as well as on the 
catalyst. 
Mixing of the liquid and vapor phases occurs in channels 32 as ascending 
vapor contacts descending liquid. The liquid phase passes through the 
permeable plates 14 and 16 from the channels into the catalyst bed 22 for 
catalytic reaction. The reaction product likewise passes from the catalyst 
bed into the channels where primary fractional distillation occurs. The 
quantity of liquid entering the catalyst zone is a function of the 
permeability of the surfaces of plates 14 and 16 and may also be regulated 
by directly introducing the liquid streams into the catalyst zone at the 
top of the structure 10. 
A material such as wire mesh is particularly advantageous for constructing 
devices 10 since this material presents a large surface area that is 
highly efficient in holding a relatively large amount of the liquid phase 
which can then engage in mass transfer with the vapor phase passing 
through the interior of the devices. 
It can thus be seen that the structure 10 provides the benefits of a 
structured packing while allowing concurrent catalytic reaction with 
distillation of fluid streams. The use of a plurality of pairs of plates 
14 and 16 enhances the distillation efficiency of the reaction process and 
at the same time provides an enclosing envelope for the catalyst bed 22 
which forms the catalytic reaction zone. The catalyst bed is maintained in 
association with the plates in a manner which virtually eliminates 
undesired channeling of the liquid phase through the bed. 
Structure 10 also provides the added benefit of allowing reuse of plates 14 
and 16 after the catalyst 24 has been expended. Renewal of the catalyst 
may be effected by removing the structure 10 from the column and 
separating the sealing member 28 from each pair of plates 14 and 16 to 
remove the catalyst bed 22. The plates may then be reused with a new 
catalyst bed being formed between the plates in a suitable manner. The 
plates are then reassembled into structure 10 and returned to the column. 
Turning now to FIG. 5, an alternate embodiment 110 of a reaction with 
distillation structure will be described. Structure 110 comprises a 
corrugated plate 114 having alternating ridges and troughs 118 and 120, 
respectively, which extend in parallel relationship to each other. 
Construction of plate 114 is identical to construction to one of the 
plates 14 or 16 previously described for the preferred embodiment. A 
planar wall member 122 is disposed on one side of plate 114 with side 
edges 124 extending in an L-shaped configuration from the planar surface 
of the member so as to wrap around plate 114. Wall member 122 is 
preferably formed from a woven material such as aluminum, steel or other 
wire mesh; nylon, Teflon and other plastic materials; or cloth material 
such as cotton, fiberglass, polyester and the like. Member 122 is 
preferably sized to completely cover one side of plate 114 and a catalyst 
bed 22 as previously described for the preferred embodiment is located 
between member 122 and plate 114. The side edges of member 122 can be tack 
welded, rivetted or otherwise rigidly secured to the side of plate 114 
which is opposite the planar surface of the member so as to provide a 
unitary rigid construction. 
Member 122 and plate 114 cooperate to provide a plurality of enclosing, 
permeable envelopes 126 of triangular cross-section with two sides of the 
envelope being presented by the corrugated plate and the third side being 
presented by planar member 122. The edge portion of member 122 which 
extends at a 90.degree. angle to the main planar surface of the member 
presents a wall for closing off the ends of each envelope 126. 
A plurality of plates 114 with catalyst in place are arranged in a manner 
previously described for structure 10. That is, a plurality of structures 
110 are positioned in side-by-side parallel relationship with the ridges 
and troughs of one row of structures being rotated 90.degree. relative to 
the plane of the structures on the next vertically adjoining row. The 
corrugated plates provide liquid flow channels 128 along the troughs 120 
on the surface of the plate opposite catalyst bed 22. The liquid will, of 
course, extend over a substantial portion of the woven surface of the 
plate for mass transfer with the vapor phase. Also, some liquid stream may 
pass through the catalyst bed 22. Catalyst bed 22 forms a catalytic 
reaction zone for reacting the descending liquid streams. The vapor phase 
formed by fractional distillation of the liquid streams will flow upward 
through the catalyst as well as through channels 128 for interaction with 
the liquid streams including mass transfer. 
During process operations, the liquid phase of the fluid streams flows 
through catalyst beds 22. As the catalyst bed becomes saturated, the 
catalytically reacted products weep from the catalyst zone through the 
permeable plates 114 and wall member 122 for mass transfer in open 
channels 128. The vapor phase primarily flows through open channels 128 
and mass transfer between the liquid and the vapor phases occurs. Some 
distillation may also occur within the catalyst bed 22 with the vapor 
phase which passes through the permeable plates 114 and wall member 120. 
Enclosing of the catalyst bed 22 in the envelopes presented by plate 114 
and wall member 122 permits the desired distillation efficiency while 
accommodating reuse of the plates 114. After the catalyst has been 
expended, structure 110 is removed from the column and one end of the 
enclosing envelopes is opened to allow the catalyst to be removed. The 
plate may then be inverted and new catalyst added through the same 
opening. 
Another alternative form of the invention is illustrated in FIGS. 7-11. 
This alternative form of the invention is designated generally by the 
numeral 210 and comprises a plurality of pairs of rigid plates 214 and 
216. Each of the plates 214 and 216 is identical and, accordingly, only 
one will be described in detail. Plate 214 is provided with a plurality of 
spaced apart concave sections 230 each of which has a truncated pyramid 
shape with sloping sidewalls 230a that converge on a planar bottom 230b. 
The plate 214 also has a plurality of second concave sections 232 which 
are of semicylindrical shape and extend between adjacent sections 230. 
Plates 214 and 216 are preferably made from a vapor/liquid permeable 
material such as wire mesh, although other alternative materials as 
discussed in conjunction with the preferred embodiment may also be 
utilized. 
When two plates 214 and 216 are disposed in facing relationship, the 
concave sections 230 and 232 are aligned so as to present first and second 
open areas 234 and 236 as illustrated in FIGS. 9 and 11. The flat areas 
238 of plate 214, which areas comprise the remainder of the plate surface 
not occupied by concave sections 230 and 232, are placed in contact with 
the corresponding area of a facing plate. These flat areas may be spot 
welded or otherwise connected to hold the two plates in rigid relationship 
thus adding considerable strength to the assembled pair of plates. 
The sections 230 at the end of plate 214 are further truncated along a 
plane lying perpendicular to the plane of the plate and when the two 
plates 214 and 216 are joined together in facing relationship end caps 240 
close off the open areas at the terminal plate ends. The end cap 240 is 
made of the same material as plates 214 and 216. Cap 240 is flush with the 
ends of the assembled pair of plates. 
A second end cap 242 (FIG. 10) is used to close off the open areas at the 
ends of the assembled plates which are opposite the ends where caps 240 
are employed. It is to be noted that end caps 242, which are made from the 
same material as plate 214, are spaced inwardly from the terminal ends of 
the two adjoining plates. 
In use, the open areas of structure 210 are filled with particulate 
catalyst material, various alternatives for which are discussed in 
conjunction with the preferred embodiment. Once the catalyst is loaded 
into the plates and the respective end caps secured, the plates are 
arranged in rows within column 212 as shown in FIG. 7 and as described in 
conjunction with the preferred embodiment. Also, as discussed in 
conjunction with the preferred embodiment, each vertical row of plates is 
preferably oriented at 90.degree. relative to the vertical planes of the 
plates in an adjacent row. 
Operation of a column with structure 210 in place for effecting concurrent 
catalytic reaction with distillation is similar to the operation 
previously described for the preferred embodiment. One or more fluid 
streams are charged to the column 212 with liquid descending through 
structure 210 and vapor ascending. Liquid will flow through the catalyst 
bed 222 and will ultimately reach the surface of plates 214 and 216 where 
it will undergo mass transfer with vapor which will preferentially be 
directed upwardly through the column following the channels presented by 
the spaces between the first concave sections 214 of each plate. In this 
regard, it is to be noted that the concave depth of sections 232 is only 
approximately one-half the depth of sections 230 so that, when two plates 
are in side-by-side touching relationship with the concave sections in 
back-to-back relationship, there will be a clear flow path for the vapor 
over the second concave sections 232 and between sections 230 of adjoining 
plates. 
From the foregoing, it will be seen that this invention is one well adapted 
to attain all the ends and objects hereinabove set forth together with 
other advantages which are obvious and which are inherent to the 
structure. 
It will be understood that certain features and subcombinations are of 
utility and may be employed without reference to other features and 
subcombinations. This is contemplated by and and is within the scope of 
the claims. 
Since many possible embodiments may be made of the invention without 
departing from the scope thereof, it is to be understood that all matter 
herein set forth or shown in the accompanying drawings is to be 
interpreted as illustrative and not in a limiting sense.