Hydroformylation process with separation and recycle of active rhodium catalyst

Active Rhodium catalyst and impurities are separated from a hydroformylation process stream containing both active and inactive organo-rhodium catalyst by binding active catalyst and impurities to an acidic ion exchange resin containing an acidic group. The purified hydroformylation stream can be returned to the hydroformylation reactor. All or a portion of inactive rhodium can be reactivated before recycling purified hydroformylation process stream to the reactor. During regeneration of the resin, a neutral solvent is used first to remove impurities which are discarded, then an acidic solvent is used to remove active organic rhodium catalyst from the resin. Such active catalyst can be rehydrided and returned to the hydroformylation reactor. An ion exchange resin having at least one acid group disposed on a silica backbone and an active organo-rhodium complex from a hydroformylation process stream bound to the resin can be produced.

FIELD OF THE INVENTION 
The invention relates to an improved hydroformylation process including 
purifying hydroformylation process streams by the separation of active 
rhodium catalyst from inactive rhodium catalyst and removal of impurities 
in hydroformylation process streams, recycling of active rhodium catalyst, 
removing impurities from recycle streams and recovery of rhodium metal 
catalysts. The separation of active from inactive catalyst enables 
recycling of active rhodium metal catalyst and removing all or a portion 
of inactive rhodium metal catalyst for regeneration and/or recovery of 
rhodium metal from inactive catalyst recycling. 
BACKGROUND OF THE INVENTION 
Rhodium metal compounds are commonly used as catalysts for organic 
reactions. One such process is hydroformylation. In the hydroformylation 
process, olefins are reacted with hydrogen and carbon monoxide to give 
linear (n-) and branched (iso-) aldehydes. The most common example is the 
manufacture of butyraldehyde from propylene and a hydrogen-carbon monoxide 
synthesis gas: 
##STR1## 
Linear aldehyde is a versatile chemical intermediate in the production of 
alcohols and plasticizers and is produced on a scale of about 4.4 million 
metric tons per year worldwide. Rhodium complex catalyst systems are 
typically utilized to permit the use of lower reaction temperatures which 
favor the production of these linear aldehydes. 
Initially despite their high activity, simple rhodium compounds were not 
attractive because they gave mostly branched aldehydes, for example, 
isobutyraldehyde, from propylene. The addition of phosphorus ligands, 
however, such as triphenylphosphine or triphenylphosphite was found to 
give active catalysts with excellent selectivity for formation of the 
desired linear aldehydes. In the presence of this catalyst, propylene 
reacts with the synthesis gas to give predominantly n-butyraldehyde. The 
selectivity to the desired linear aldehyde is very high, greater than 90% 
when excess phosphorus ligand is present. The ligand is important to 
stabilize the catalyst during product recovery as well as to direct the 
reaction to formation of the desired product. Since both selectivity and 
stability are favored by a large excess of ligand, molten 
triphenylphosphine is an ideal solvent for the reaction, and the catalytic 
rhodium complex is stable almost indefinitely in this medium. 
In a continuous catalytic hydroformylation process with molten 
triphenylphosphine (TPP) as the more volatile constituents are separated 
and, rhodium catalyst remains in the recirculating higher-boiling and 
triphenylphosphine solvent. The build up of impurities in the 
recirculating solvent and the gradual deactivation of a portion of the 
rhodium catalyst prevent the hydroformylation process from operating 
continuously for an infinite duration. Typical impurities are aryl 
phosphine oxide, alkyl phosphine oxide, mixed phosphines, mixed phosphine 
oxides, high molecular weight organic compounds, and trace metals. 
Gradually, rhodium catalyst becomes deactivated for reasons not well 
understood but probably associated with the reaction temperature and the 
presence of the impurities. Higher process temperature can be used to 
affect the presence of inactive catalyst, as higher temperature can cause 
olefin to be driven off during the conversion process resulting in a lower 
olefin yield. When its catalyst activity drops to an unacceptable level, 
to maintain throughput the reactor is shut down, cleaned, and restarted, 
which for normal operation occurs approximately every two years. 
Although the catalyst containing residue can be recycled to the 
hydroformylation process, the amount of residue progressively increases 
while the catalyst activity progressively decreases. In order to 
compensate for the drop in catalytic activity and maintain the aldehyde 
throughput, it would be desirable to add additional active rhodium 
catalyst and remove inactive catalyst and impurities. 
Due to the high cost and scarcity of rhodium metal, numerous prior art 
processes have been developed to recover and reactivate the rhodium 
catalyst so that it may be used again in the hydroformylation process. An 
example of such a process involves concentrating a hydroformylation 
reaction mixture by a wipe film evaporator and then air oxidizing. The 
rhodium catalyst is then reactivated by exposure to synthesis gas. Such 
conventional recovery and reactivation processes for this purpose, 
however, have proved rather unsatisfactory since the hydroformylation 
process must be discontinued and the reactor shut down in order to recover 
and reactivate the catalyst. Furthermore, even after such a process, the 
reactivated catalyst cannot be reactivated to 100% of its original 
activity. 
One known process involves removal of a portion of the process stream as a 
bleed stream i.e. a relatively small stream in comparison to quantity of 
recirculating solvent and catalyst. For example the bleed stream might 
remove 1 to 2 percent of the reactor contents per day. The bleed stream 
goes to a storage vessel and then when the storage vessel is full it is 
reactivated by removing butyl diphenyl phosphine and oxidizing the 
reforming catalyst. This technique would remove only about 0.5 kg of 
rhodium per day from the reactor. This process is not used because 
efficient operating conditions are now known that minimize butyl diphenyl 
phosphine formation and the reactor can run for two years without the 
necessity for removing a bleed stream. However, after two years the 
reactor must be emptied and recharged. 
Other prior art rhodium recovery processes have also been developed. These 
conventional approaches are generally directed toward removing Group IX 
and X transition metals (Co, Rh, Ir, Ni, Pt, Pd,) and include extraction 
with aqueous solutions, addition of precipitating agents or a combination 
of these techniques. Extraction of Group IX and X metals from organic 
mixtures using aqueous acetic acid is disclosed in European Patent No. 0 
255 389. Using aqueous amine solutions is disclosed in U.S. Pat. No. 
4,292,196. Use of aqueous alkaline cesium salt solution and crown ether is 
disclosed in U.S. Pat. No. 4,363,765. Aqueous solutions of ionic 
organophosphines for rhodium recovery is disclosed in U.S. Pat. No. 
4,935,550. Another rhodium recovery method using amine/HCN mixtures is 
disclosed in J. Am. Oil Chemists Soc. 54 (1977) 276. 
Precipitation of the Group IX and X metal compound, followed by either 
extraction or filtration of the precipitate is a second general approach. 
Examples include precipitation by peroxide treatment of an organic mixture 
containing the Group IX and X metal catalyst (U.S. Pat. No. 3,547,964), 
reductive treatment with hydrogen/catalyst or a hydride reducing agent 
(U.S. Pat. No. 4,560,539), precipitation of agglomerated rhodium from 
neutralized distillation residues (U.S. Pat. Nos. 3,998,622 and 
4,135,911), oxidation under basic conditions (U.S. Pat. No. 4,396,551), 
treatment with an organic sulfur compound to form a precipitate (U.S. Pat. 
No. 4,413,118) and treatment with a carboxylic acid to precipitate an 
active catalyst (U.S. Pat. No. 4,950,629). 
None of these known processes, however, can be utilized continuously with a 
hydroformylation process. Moreover, most of these prior art processes 
which treat hydroformylation waste streams, require extensive pretreatment 
in order to remove residual organic compounds prior to recovering rhodium. 
Ion exchange methods have also been used to recover rhodium metals from 
aqueous solutions, as described in U.S. Pat. Nos. 2,945,743 and 3,567,368. 
Basic ion-exchange resins have been used to recover rhodium as described 
in U.S. Pat. No. 3,755,393. Group VIII metals have also been recovered 
from organic solutions using either a solid absorbent, such as calcium 
sulfate, molecular sieves, or an anionic ion-exchange resin as disclosed 
in U.S. Pat. No. 4,388,729. 
Acidic ion exchange resins have also been used to recover Group IX and X 
transition metals. U.S. Pat. No. 5,114,473 discloses using a phosphorus 
containing ion-exchange resin which weakly binds the transition metal. 
U.S. Pat. No. 4,113,754 discloses using sulfonic acid resins which swell 
when contacted with different solvents and require pretreatment of the 
process streams which takes several days and precludes incorporating 
catalyst recovery into a continuous process. U.S. Pat. No. 5,208,194 
discloses acidic ion-exchange resins containing sulfonic acid groups to 
bind a Group VIII transition metal carbonyl complex which is recovered by 
burning off (ashing) the resin. 
The prior art processes using acidic ion-exchange resins to recover and 
reactivate Group IX and X transition metals such as rhodium metal from 
organic solutions are batch processes, i.e., not continuous. 
SUMMARY OF THE INVENTION 
The present invention provides an improved hydroformylation process having 
one or more of the following improvements: selectively separating active 
rhodium catalyst from inactive rhodium catalyst; removing active rhodium 
catalyst from a hydroformylation stream; removing impurities from a 
hydroformylation stream; recovering and reactivating inactive rhodium 
catalyst from a hydroformylation process stream; recycling reactivated 
catalyst; and rehydriding and recycling active catalyst previously removed 
from a hydroformylation process stream containing impurities. 
Selective separation of active rhodium catalyst from inactive rhodium 
catalyst contained in a hydroformylation process stream containing both 
active and inactive organo-rhodium catalyst complex is accomplished with 
an ion exchange resin having a functional acid group attached to a 
silia-containing backbone. 
A method for recovering an organo-rhodium catalyst from a hydroformylation 
process stream containing an organo-rhodium catalyst complex comprises the 
steps of (a) purifying a hydroformylation process stream containing 
triphenylphosphine, active organo-rhodium catalyst complex, inactive 
organo-rhodium catalyst complex and impurities with an ion-exchange resin 
containing an acidic group whereby active organo-rhodium catalyst complex 
and impurities in the process stream become bound to the resin; (b) 
separately removing impurities and active organo-rhodium catalyst complex 
from the resin; (c) rehydriding and recycling active rhodium catalyst 
removed from the resin; and (d) recycling purified hydroformylation 
process stream to the hydroformylation process. 
The method can further include after step (a), the step of reactivating all 
or a portion of the deactive catalyst in the purified hydroformylation 
process stream and returning reactivated catalyst to a hydroformylation 
reactor. 
The process is based on the discovery that contacting a hydroformylation 
stream containing active and inactivated organo-rhodium catalyst with 
certain acidic ion-exchange resins results in selective separation of 
active from inactive organo-rhodium catalyst due to active catalyst being 
more strongly bond to the resin as are certain impurities present in the 
stream. 
Suitable resin include resin having an sulfonic acid group or carboxylic 
acid group which bind organo-rhodium catalyst in a portion of the 
hydroformylation stream. Examples of ion exchange resins having acidic 
group such as aromatic sulfonic acid, carboxylic acid, and propyl sulfonic 
acid are sold under the trademark Bakerbond by J. T. Baker Chemical 
Company, and cross-linked acidic 3-sulfopropyl methacrylate resins. 
The resin with the bound active organo-rhodium catalyst complex and 
impurities is regenerated and active catalyst after being rehydrided is 
recycled to the hydroformylation process. Regeneration is a multi step 
process that separately removes active catalyst and impurities from the 
resin. Before regeneration, the resin is preferably washed with a solvent 
to remove any portion of the hydroformylation process stream (e.g. 
triphenylphosphine, aldehyde, reactor solvent, triphenylphosphine oxide, 
organic condensation product) and any unbound rhodium catalyst which can 
be recycled to the hydroformylation process. This solvent is selected so 
as not to interfere with the hydroformylation process when introduced into 
the hydroformylation reactor with recycled hydroformylation process 
stream. The resin is regenerated by first being washed with a solvent to 
remove a substantial portion of the impurities, e.g. aryl phosphine oxide, 
alkyl phosphine oxide, mixed phosphine oxide, and high molecular weight 
organic compounds. The resin after this first washing is substantially 
free of impurities and still binds the active organic-rhodium catalyst 
complex and a small portion of triphenylphosphine. The resin is then 
acidified by being washed with an acidified solvent to remove the bound 
active organo-rhodium catalyst complex. Acidification of the resin 
produces a rhodium-containing solution, from which the active rhodium 
catalyst is recovered and rehydrided so that it can be recycled to a 
hydroformylation reaction.

DETAILED DESCRIPTION OF THE INVENTION 
The process of the present invention provides a process for treating a 
hydroformylation process stream that: (a) removes impurities from the 
hydroformylation process stream; (b) selectively separates active rhodium 
from inactive catalyst in the hydroformylation process stream; (c) 
rehydrides and recycles active catalyst; (d) recycles a purified 
hydroformylation process stream; and, (e) reactivates inactive rhodium 
catalyst and recycles reactivated rhodium catalyst to the hydroformylation 
process. The process utilizes an acidic ion exchange resin for purifying 
the hydroformylation process stream and for selectively separating active 
from inactive rhodium catalyst contained in the stream. Removing of 
impurities and selective separation of active from inactive Rhodium 
catalyst from a hydroformylation process stream can be accomplished 
because of the selective binding characteristics of a particular type of 
acidic ion exchange resins. When a hydroformylation process stream 
containing impurities, active rhodium catalyst and inactive rhodium 
catalyst contacts the resin, impurities and active catalyst are bond to 
the resin. This simultaneously removes impurities such as mixed phosphines 
and phosphine oxides and active catalyst from a hydroformylation process 
stream containing triphenylphosphine, even in the presence of 
hydroformylation products (aldehydes), reactants and/or inactive rhodium 
catalysts. With such resins, recycling of active catalyst to a 
hydroformylation reactor and removal of impurities from the 
hydroformylation process can be continuously practiced with an appropriate 
sequence of process steps depicted in FIG. 1. The recovery method can be 
applied to any hydroformylation process stream that contains impurities 
from the hydroformylation reaction and/or active and inactive rhodium 
catalyst. Reaction product from the hydroformylation process, such as 
aldehydes may be present or can be removed before treating the process 
stream with the resin. Thus streams containing product and those streams 
having a high level of impurities can be treated to remove impurities and 
separate active from inactive rhodium catalyst. 
A substantially improved hydroformylation process is shown in the FIG. 1 
having better control of the level of catalytic activity and impurity 
concentrations in the hydroformylation reaction vessel. This is 
accomplished by using an acidic ion exchange resin for separating active 
from inactive rhodium catalyst and removing impurities from the 
hydroformylation stream containing triphenylphosphine and solvents. 
Typically the catalytic activity of a rhodium catalyst in a 
hydroformylation process will degrade at an increasing rate per day of 
operation of the process. Thus, in order to maintain a constant level of 
catalytic activity in a hydroformylation reactor, a sufficient quantity of 
active catalyst must be added to the reactor to compensate for the daily 
loss in catalytic activity. With the present invention the source of 
active catalyst can be recycled active rhodium catalyst, inactive catalyst 
that has been reactivated, fresh rhodium catalyst, or any combination 
thereof. Preferably, the purified hydroformylation stream is recycled 
continuously after passing through the acidic resin column. A portion of 
the purified hydroformylation process stream can be removed as a bleed 
stream as shown in FIG. 1 to further control the accumulation of 
undesirable chemicals due to recycling. 
The purification and catalyst recovery process according to the present 
invention can be utilized in combination with conventional 
hydroformylation processes to obtain an improved hydroformylation process 
approaching steady state catalytic activity level and control of the 
concentration of impurities thus producing a more uniform hydroformylation 
product. This is accomplished by treating at least a portion of a 
hydroformylation process stream containing rhodium catalyst and 
triphenylphosphine in a column containing an acidic ion exchange resin to 
remove impurities and active rhodium catalyst and recycling the purified 
stream to the hydroformylation reaction vessel. The active rhodium and the 
impurities can be removed from the resin column, separated and the active 
catalyst can be returned to the hydroformylation process. Inactive 
catalyst in the purified stream can be reactivated prior to being recycled 
to the hydroformylation reaction vessel. 
The impurities and catalyst can be separately removed from the resin and 
the resin regenerated by washing the resin to remove organic and 
phosphorus compounds and acid solvent washing the column to remove the 
active rhodium catalyst from the resin column, and preferably recycling 
the active catalyst to the hydroformylation process. The regenerated resin 
is also reused. 
The term "hydroformylation process stream" as used herein is defined as any 
stream which is obtained from any point in a hydroformylation process and 
containing active and inactive rhodium catalyst and hydroformylation 
impurities. Examples of such catalysts are rhodium complexed with 
phosphorus ligands, typically comprising rhodium in solvents such as 
2,2,4-trimethyl-1,3-pentanediol mono (2-methypropanoate) containing a 
substantial amount of phosphorous ligands such as triphenylphosphine or 
triphenylphosphite. 
The top portion of FIG. 1 depicts a typical prior art hydroformylation 
process comprising a series of steps including hydroformylation in reactor 
10, separation of unreacted ingredients such as H.sub.2 CO and olefin from 
the hydroformylation process stream, in separator 12 followed by removal 
of aldehyde product in evaporator 14. Reactants feed into reactor 10 are 
hydrogen, carbon monoxide, and an olefin to be converted into an aldehyde 
by hydroformylation. The catalyst added to reactor 10 is a conventional 
organo-rhodium catalyst, i.e. complexed with phosphorus ligands, typically 
comprising rhodium in solvents such as 2,2,4-trimethyl-1,3-pentanediol 
mono (2-methypropanoate) and containing a substantial amount of 
phosphorous ligands such as triphenylphosphine or triphenylphosphite. The 
catalyst stream is introduced into the hydroformylation reactor 10 in 
order to provide catalyst for the reaction. On process start-up, the 
catalyst stream ordinarily comprises fresh catalyst and solvent. In a 
conventional process, after start-up, the catalyst in reactor 10 is 
composed of recycle stream 16 with fresh catalyst added as necessary to 
make up for degradation in catalyst activity in reactor 10 and catalyst 
losses. Unreacted low boiling point components remaining after 
hydroformylation are removed in flash separators 12. In conventional 
hydroformylation processes the light ends (H.sub.2, CO and olefin such as 
propylene), shown as stream 42 in FIG. 1 are driven off in separator 12 
and may be recycled. This is followed by an evaporation step as shown by 
evaporator 14 from which aldehyde product is removed. The residue or 
unvaporized portions from evaporator 14 is removed as recycle stream 16 
which includes active and inactive catalyst, solvent, ligands, impurities, 
and sometimes a small quantity of product and unreacted feed chemicals. 
Stream 16 can be recycled back to reactor 10, with or without rhodium 
catalyst separation and impurity removal prior to recycling to reactor 10. 
The continuous hydroformylation process of the present invention reduces 
the need to add fresh catalyst to the hydroformylation process for 
controlling catalytic activity. The improvement treats at least a portion 
of recycle stream 16 containing active and inactive rhodium catalyst, 
ligands and impurities to selectively separate active rhodium from 
inactive rhodium catalyst and to remove impurities from stream 16. 
Although all of stream 16 can be treated in a resin column, preferably a 
bleed stream 44 is removed from direct recycle stream 16, the latter 
returning untreated catalyst to the hydroformylation reactor in the same 
manner as a conventional recycle stream. Bleed stream 44 is treated within 
acidic ion exchange resin column 18 or 20 which selectively removes 
impurities and active rhodium catalyst from bleed stream 44. Impurities 
and active rhodium catalyst can be subsequentially separated from the 
resin during regeneration of the resin column (e.g. 18 or 20) by ion 
exchange. After removal of active rhodium catalyst during regeneration of 
the ion exchange resin the active catalyst needs to be rehydrided before 
being reintroduced into the hydroformylation reactor 10. This can be 
accomplished in reactor 28 where active catalyst stream 26 obtained during 
regeneration of the ion exchange resin is contacted with H.sub.2 +CO. The 
rehydrided active rhodium catalyst 46 is preferably separated from 
byproducts in separator 30 by processes such as filtration or a phase 
split which can remove unwanted by-products from rehydriding. The active 
rhodium catalyst-solvent stream 32 after being rehydrided is recycled to 
the hydroformylation reactor. 
The process can be described in greater detail with reference to FIG. 1. 
Conventional hydroformylation is shown in the top portion of FIG. 1 which 
involves; hydroformylation of an olefin in reactor 10 usually at elevated 
temperature and pressure in a stream containing H.sub.2, CO, olefin, 
conventional rhodium catalyst complex and trisphenylphosphine; separation 
of unreacted chemicals (H.sub.2, CO and olefin) in separator 12; removal 
in 14 of hydroformylation products usually by evaporation; and, recycling 
of stream 16 containing reaction solvents, ligands and rhodium catalysts. 
The improvement provided by the present invention in a conventional 
hydroformylation process comprises (a) treating at least a portion of 
recycle stream 16 in a resin column, i.e. 18, to remove impurities and 
active rhodium catalyst to produce purified recycle stream 22; 
(b)returning at least a portion 40 of purified recycle stream 22 to the 
hydroformylation reactor 10; (c) sequentially removing impurities 48 and 
then removing active rhodium catalyst from resin column 18 with catalyst 
removal solvent 24 to produce stream 26 containing active rhodium catalyst 
for recycling; (d) treating active rhodium recycle stream 26 in rehydridor 
28 with H.sub.2 and CO to produce rehydrided active rhodium catalyst 
stream 46; (e)removing undesirable byproducts of rehydriding from stream 
46 in separator 30; and (f) recycling active rehydrided rhodium catalyst 
32 to the hydroformylation reaction in reactor 10. Optionally, inactive 
rhodium catalyst contained in purified recycle stream 22 can be 
reactivated according to conventional technology such as by wipe film 
evaporation, followed by oxidation and subsequent reduction by treating 
all or portion 38 of stream 22 in reactivation processor 34 to produce 
reactivated recycle stream 36. The level of catalytic activity in reactor 
10 can be controlled by selecting the portion 38 of recycle stream 22 so 
that the quantity of reactivated catalyst in stream 36 approximately 
equals the amount of catalytic activity being lost in reactor 10. 
When the hydroformulation reaction is being operated on a continuous basis, 
the rate that catalytic activity is being lost can be counterbalanced to 
maintain level catalytic activity by adjusting the proportion of stream 38 
to stream 22 so that the rate that catalyst is being reactivated in 34 and 
returned to reactor 10 through recycle stream 36 approximately equals the 
rate that catalyst is being deactivated in reactor 10. Prior to the 
present invention separation of active from inactive catalyst was not 
achievable and both active and inactive catalyst had to be put through the 
reactivation step in order to recycle reactivated catalyst to reactor 10. 
The catalytic activity of the improved hydroformylation process can be 
controlled by controlling the amount of active catalyst entering the 
hydroformylation reactor 10. The amount of active catalyst entering 
reactor 10 equals the sum of (1) active rehydrided rhodium catalyst in 
stream 32, (2) reactivated catalyst in stream 36 and fresh make up 
catalyst added to reactor 10. Catalytic activity can be maintained at a 
uniform level in reactor 10 by controlling the quantity of the catalyst 
reactivated in processor 34 and recycled in stream 36 to compensate for 
the amount of catalyst becoming deactivated in the hydroformylation 
process and by adding an amount of fresh catalyst to reactor 10 to make up 
for catalyst losses in the separation steps and resin regeneration. The 
quantity of catalyst reactivated in processor 34 can be controlled by 
sending only a portion of stream 22 to the reactivation processor 34 and 
directly recycling stream 40 without reactivation of the catalyst in 
stream 40. 
Purification of hydroformylation process stream 16 and separating active 
from inactive catalyst can be practiced continuously by utilizing more 
than one resin column. FIG. 1 shown two resin columns, 18 and 20. 
Continuous operation can be achieved by regenerating one column, e.g. 18, 
while another column is treating stream 16. In this way a continuous or 
almost continuous source of purified recycle stream 22 is obtained from 
the column treating stream 16 while a continuous or almost continuous 
source of stream 26 containing active catalyst can be obtained from the 
other column being regenerated. 
The key step of the process method comprises the step of contacting at 
least a portion of a hydroformylation process stream 16 containing 
triphenylphosphine, active rhodium catalyst, inactive rhodium catalyst and 
impurities with the acidic ion-exchange resin. The resin has a 
silica-containing backbone with a functional acid group attached to the 
silica. The acid group is typically selected from the group consisting of 
an aromatic sulfonic acid, an aliphatic sulfonic acid, an aromatic 
carboxylic acid, and an aliphatic carboxylic acid. The present invention 
also includes an intermediate composition having at least one sulfonic 
acid group disposed on a silica backbone and an organo-rhodium complex 
from a hydroformylation process stream bound to the resin. 
Prior to using the acidic ion exchange resin for the first time the resin 
is preferably pretreated by washing with a variety of solvents in order to 
ensure that the active groups on the resin have an acidic structure rather 
than a salt structure, e.g. for a sulfonic acid resin, a sulfonic acid 
structure and not a sulfonate salt structure. This pretreatment comprises 
first washing the resin with an acidified solvent, followed by washing and 
adjusting the effluent pH to neutral. Before use the column may be washed 
with a resin pretreatment stream which comprises a suitable solvent such 
as dialcohol ester solvent, sold under the trade name TEXANOL by Eastman 
Chemical Company, which will not interfere with a hydroformylation 
process. This solvent is an ester alcohol having the chemical name 
2,2,4-trimethyl-1,3-pentanediol mono (2-methypropanoate). Another suitable 
solvent is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate. This final 
wash converts the solvent held upon the column to 
2,2,4-trimethyl-1,3-pentanediol mono (2-methypropanoate), this will allow 
the solution from the column to be recycled back to the reactor. Without 
this step the introduction of another solvent to the reactor could occur 
which is preferably avoided. 
Operation of the Column 
After the resin is charged into the column active rhodium catalyst and 
impurities can be removed from stream 16 with the acidic ion exchange 
resin. Stream 16 contains an organo-rhodium catalyst complex and is passed 
through the column containing the resin in order to bind at least a 
portion of the active rhodium catalyst to the sulfonic or other active 
acid groups of the resin. Typically the active organo-rhodium catalyst is 
a complex with a Phosphorus Ligand such as TPP (triphenylphosphine). 
Stream 16 is passed through the resin column for a period of time up to 
the time for saturation the resin, e.g. about 100 g of process stream/g of 
resin. Once saturated the resin with bound active organo-rhodium catalyst 
complex can be regenerated. 
Regeneration of Resin 
The resin column to be regenerated is first isolated from the 
hydroformylation process by cutting off the flow of stream 16 to the resin 
column. A first solvent stream or pre-wash is added through line 24 to 
remove or displace remaining hydroformylation stream 16 containing unbound 
organo-rhodium catalyst complex from the column. Preferably the first 
solvent is compatible with the hydroformylation reaction and the pre-wash 
from the column is recycled back to reactor 10 with stream 16 containing 
unbound organo-rhodium catalyst complex. 2,2,4-trimethyl-1,3-pentanediol 
mono (2-methypropanoate) solvent is preferred as the first wash solvent 
because it is the solvent for adding catalyst to the hydroformylation 
reactor 10. 
After the optional pre-wash, regeneration of the resin column is 
accomplished when the resin column is washed with a second solvent to 
remove from the resin, impurities originally contained in stream 16 such 
as aryl phosphine oxide, alkyl phosphine oxide, mixed phosphine oxide, and 
high molecular weight organic compounds. The heavy organic compounds are 
organic condensation products which otherwise build up in reactor 10. The 
preferred solvent for this purpose is alcohol. This washing off of 
impurities produces a resin having bound active organo-rhodium catalyst 
complex substantially free of impurities. The effluent from this 
impurities wash is removed as a waste stream 48 and disposed of. It should 
be noted that during this impurities wash the resin still holds (binds) 
the bound active organo-rhodium catalyst complex. This selective holding 
(binding) by the resin permits separation and removal of impurities. The 
impurities if not removed can accumulate and contribute to poisoning the 
catalyst (i.e., decrease the activity of the catalyst) and lead to 
extinction of the hydroformylation process over time. 
After the wash with alcohol or other non acidic solvent to remove bound 
impurities from the resin, the resin is then acidified using an acidified 
solvent such as hydrochloric acid in isopropanol to remove the bound 
active organo-rhodium catalyst complex and produce a solution 26 
containing active rhodium catalyst in the form of an organo-rhodium 
catalyst complex. Typically this would be (TPP)nRH.sup.(I) Cl. This 
acidified solvent can comprise an alcohol (such as isopropyl alcohol and 
methanol), THF, toluene, or heptane in conjunction with an acid such as 
hydrochloric. If an acidified alcohol or heptane is used as the acidified 
solvent, the resin must also be washed using a fourth solvent such as 
toluene or tetrahydrofuran in order to prevent the organo-rhodium catalyst 
complex from precipitating onto the resin. 
In acidifying the resin and removing active catalyst, the more acidic the 
solvent, the faster the active organo-rhodium complex catalyst is released 
from the resin. The acidic solvent used should have a pH below 4 with 1 to 
4 being preferred to remove the organo-rhodium catalyst complex, although 
a solvent with a pH less than 1 may be used. This step serves two purposes 
it removes the active catalyst from the resin and it also reactivates 
(i.e. regenerates) the resin so that it will bond more active catalyst. 
Catalyst in stream 26 obtained during regeneration with the acidic solvent 
is active but it is in a form that is not compatible with the 
hydroformylation reactor 10. It is made compatible by rehydriding in 
reactor 28. 
Rehydriding 
The active organo-rhodium complex catalyst and solvent stream 26 obtained 
during regeneration of the acidic ion exchange resin is introduced into a 
rehydridor reactor 28 for rehydriding the organo-rhodium complex catalyst 
by reacting it H.sub.2 and CO. Stream 26 consists of active catalyst, e.g. 
(Phosphorus Ligand).sub.n Rh(I).sup.X complex in the acidic solvent, 
wherein X is Cl if HCl is used as the solvent. Active catalyst is obtained 
from the resin in the column with the acidified solvent. The most 
economical means for rehydriding is to place reactor 28 under pressure 
with of H.sub.2 and CO. Triphenylphosphine (TPP) can be added to reactor 
28. An acid scavenger such as Triethyl amine may also be added to scavenge 
the HCL. This reaction generates an active rhodium catalyst species. 
Rehydriding of active organo-rhodium catalyst complex can be also 
accomplished by contacting stream 26 with a hydriding agent such as sodium 
hydride, sodium borohydride, or aluminum trialkyl introduced into reactor 
28. This will convert the (Phosphorus Ligand).sub.n Rh.sup.(I) Cl to 
(Phosphorus Ligand).sub.n Rh.sup.(I) H. The rehydrided catalyst is removed 
from reactor 28 as stream 46 and introduced into separator 30 where an 
amine hydrochloride and/or sodium chloride by-products are removed such as 
by filtering or by a phase split. 
The stream 32 from separator 30 contains rehydrided organo-rhodium complex 
catalyst (preferably in a solution of 2,2,4-trimethyl-1,3-pentanediol mono 
(2-methypropanoate) and is recycled back into the hydroformylation reactor 
10. The recycle process can be operated continuously in according to 
conventional chemical engineering practices in order to maintain a steady 
state activity level of the catalyst in the hydroformylation reaction. 
Typically, this is accomplished with multiple ion exchange columns with 
one being regenerated while one is separating catalysts and removing 
impurities from stream 16. 
After removal of the active catalyst the resin can be washed with a solvent 
such as a neutral pH solution of 2,2,4-trimethyl-1,3-pentanediol mono 
(2-methypropanoate) solvent after regeneration before being placed back 
into service treating stream 16 in order to prepare for a new cycle of 
binding and removing active rhodium catalyst from a hydroformylation 
process output stream. 
Several polar and non-polar solvents including: heptane, 
2,2,4-trimethyl-1,3-pentanediol mono (2-methypropanoate), tetrahydrofuran 
(THF), methanol, and isopropyl alcohol and mixtures thereof can be used in 
the process as the solvent for a prewash of the ion exchange column before 
regeneration. The prewash solvent must be primarily non-polar and neutral 
pH so as not to remove impurities or active catalyst from the resin. 
However a prewash is not necessary in practicing the invention. During 
regeneration, the first wash to remove impurities must be primarily with a 
polar solvent at about neutral pH so as to remove impurities but retain 
most of the active catalyst on the resin. The removal of active catalyst 
from the resin is accomplished with acidified solvent, either polar or 
non-polar and at a pH of 4 or less. It has been observed that non-polar 
solvents release less Rh from the resin than polar solvents. When heptane 
is used as the pre-wash solvent less than 1.0% of the Rh is removed. When 
2,2,4-trimethyl-1,3-pentanediol mono (2-methypropanoate) is used as the 
pre-wash solvent less than 4.5% of the Rh is removed. This effluent from a 
pre-wash can be returned to the reactor; therefore, there is no loss of Rh 
from reactor for this pre-wash step (this is especially true when using 
2,2,4-trimethyl-1,3-pentanediol mono (2-methypropanoate) is used). The 
effluent 48 from resin wash with a polar solvent is diverted away from the 
reactor because stream 46 contains a bulk of the impurities such as TPPO 
and organic heavies that should be removed from the reactor. The use of 
tetrahydrofuran (THF) as the polar solvent wash can remove up to 2% of the 
Rh from the resin. The use of alcohols (such as methanol or isopropyl 
alcohol) as the polar solvent can remove as much as 46 of the Rh from the 
resin. 
The preferred pre-wash solvent is 2,2,4-trimethyl-1,3-pentanediol mono 
(2-methypropanoate). Other possible pre-wash solvents include: alkanes 
(heptane, hexane(s), octane(s)), toluene, and xylene(s). 
The preferred polar solvent is tetrahydrofuran (THF). Other possible wash 
solvents for removal of impurities include, alcohols (methanol, isopropyl 
alcohol, butanol(s), 2-ethyl-1-hexanol), ethers (methyltert-butyl ether, 
butyl ether), ketones (acetone, methyl ethyl ketone, methyl propyl 
ketone), toluene, and xylene(s). 
Operation with Two Columns 
Preferably, the present invention is operated with more than one column. 
After the acidic ion exchange resin in column letter A or B, has absorbed 
impurities and active rhodium catalyst it can be regenerated while another 
column is used to treat stream 16 sequentially. During regeneration 
impurities as stream 48 are removed which are discarded from the 
hydroformylation process. Then active rhodium catalyst is removed from the 
resin in stream 22 and recycled back to the hydroformylation reactor 10 
after being rehydrided. The following steps are the preferred regeneration 
process of column A while column B is treating stream 16: (1) wash the 
resin in column A with a non-polar pre-wash solvent, such as 
2,2,4-trimethyl-1,3-pentanediol mono (2-methypropanoate). This wash will 
remove the non-bonded Rh, and a small percentage of the TPP, TPPO, and 
organic heavies from the column and return it to the reactor along with 
stream 16; 
(2) A first wash solvent preferably tetrahydrofuran (THF) is passed through 
column A to remove the bulk of impurities such as the TPP, TPPO, and 
organic heavies as stream 48. Stream 48 is discarded from the 
hydroformylation process. (In preferred case the THF and 
2,2,4-trimethyl-1,3-pentanediol mono (2-methypropanoate) can be distilled 
over head from stream 46 and reused); 
(3) The active Rh catalyst is removed from the column as stream 26 with an 
acidified solvent. 
The preferred acidified solvent is a blend of THF and isopropyl alcohol 
that has been acidified with an acid such as hydrochloric acid to a pH 
below 4. Other possible wash solvents that can be acidified and used as 
the acidified solvent are: ketones (acetone, methyl ethyl ketone, methyl 
propyl ketone), ethers (methyl-tert-butyl ether, butyl ether), toluene, 
and xylene. The preferred acid is hydrochloric acid, other possible acids 
include hydrobromic, hydroiodic, formic, acetic, chloroacetic, 
fluoroacetic, dichloroacetic, trifluoroacetic, and trichloroacetic acids. 
Other acids such as citric, 2-ethyl-1-hexanoic, methyl sulfonic acids are 
believed to be effective. 
Although stream 16 is shown in FIG. 1 as being separated from the reactor 
output after evaporator 14, alternatively it may be taken before the 
evaporator. In either case, stream 16 contains active and inactive rhodium 
catalysts and impurities such as aryl phosphine oxide, alkyl phosphine 
oxide, mixed phosphines, mixed phosphine oxide, and high molecular weight 
organic compounds which can be selectively removed with the acidic ion 
exchange resin. 
The rhodium recovery process shown schematically in FIG. 1 comprises two 
resin columns A and B which are alternately contacted with stream 16. 
While one column is sorbing the active rhodium catalyst and impurities 
from stream 16, the separation of impurities from active rhodium catalyst 
by the regeneration steps disclosed above can be performed on the other 
column which has already been in contact with stream 16. Use of multiple 
columns increases the speed with which the continuous recovery process can 
be operated so that increased recovery speeds can be accomplished. 
The resins used as the acidic ion exchange resin it must be capable of 
selectively binding active rhodium catalyst tightly enough to permit the 
removal of impurities from the resin during regeneration without removing 
active catalyst from the resin when washed with the neutral solvent and 
release the active rhodium catalyst when washed with the solvent with a pH 
of 4.0 or less. Moreover, the resin should not absorb inactive rhodium 
catalyst from stream 16 as readily as it absorbs active catalyst. 
Moreover, these resins preferably do not appreciably change volume (i.e., 
swell) when using the various solvents required by the recovery process, 
thus enabling continuous recovery within a resin bed, utilizing various 
polar & non-polar, protic and non-protic solvents without any special 
pretreatment or processing steps. These properties facilitate recycle of 
the resin and the catalyst in a continuous manner. Three selective 
separations are achievable with the acidic ion exchange resin. First, 
active rhodium and impurities are preferentially removed from 
hydroformylation stream 16 while in comparison to inactive rhodium 
catalyst which tend to remain in stream 16. Second, during regeneration of 
the resin, impurities can be selectively separated from active rhodium 
resin by appropriate selection of solvents used in regeneration of the 
resin. Impurities are preferentially removed from the resin with polar 
solvents that are essentially neutral e.g. a pH between 6 and 8 while 
active rhodium catalyst is retained on the resin. Third, active rhodium 
catalyst is removed from the resin with a solvent having a pH below 4. 
Certain commercial resins were found to be effective. In general, the 
resins used in the present invention have a molecular structure in which 
an active group is attached to a cross-linked polymer or network polymer. 
The resins found effective (i.e., able to recover and reactivate a high 
proportion of the rhodium in the recycle stream) were an aromatic sulfonic 
acid, propyl sulfonic acid and carboxylic acid sold by J. T. Baker, under 
the name Bakerbond. All of the resins that contain sulfonate or 
carboxylate groups and a silica backbone are effective in binding the 
rhodium catalyst and did not swell while performing the continuous 
recovery process of the present invention. Also an acidic cross-linked 
3-sulfopropyl methacrylate sulfonic acid resin is effective at selectively 
binding and sequentially releasing impurities and then active rhodium. 
The commercially available aromatic resins suitable for use in the present 
invention can be manufactured by the condensation reaction of a hydroxy 
aromatic sulfonic acid and silica to produce the defined supported 
aromatic sulfonic acid resin on silica structure. A typical manufacturing 
method can comprise the condensation reaction of silica having a defined 
porosity, preferably with an average pore size of approximately 40 
micrometers, with a hydroxy aromatic sulfonic acid to produce a supported 
aromatic sulfonic acid resin on silica with water as a by-product. This 
condensation reaction can be accomplished by adding the hydroxy aromatic 
sulfonic acid to the silica and heating it under vacuum at a temperature 
and for a time until the reaction is complete, i.e., until water is no 
longer is produced. 
Aliphatic sulfonic acid resins and carboxylic resins useful in the present 
invention and discussed above can be manufactured in similar fashion by 
replacing the aromatic sulfonic acid starting material in the condensation 
reaction with either hydroxy aliphatic sulfonic acids or hydroxy aliphatic 
carboxylic acids respectively. 
It is believed that the condensation reaction which occurs is between the 
hydroxyl group of the hydroxy acid and the hydroxyl group on the silica to 
produce a supported resin having an acidic group connected by a tether. 
The tethered acidic group acts as the active group for binding the 
rhodium. Depending on the starting material reacted with the silica, the 
tether is either an aromatic group or an aliphatic group and the acidic 
group is either a carboxylic acid or sulfonic acid. In the case of a 
sulfonic acid active group, the structure of the acid group which binds 
the rhodium is a sulfonate, SO.sub.3 --, group. In the case of a 
carboxylic acid active group, the structure of the acid group which binds 
the rhodium is a carboxylate, CO.sub.2 --, group. 
Empirical rhodium recovery tests using the procedure set forth below were 
performed using these ion exchange resins to evaluate their efficacy in 
recovering rhodium catalysts from hydroformylation waste streams. 
RESIN SELECTION 
Following is a step-by-step process used to screen acceptable resins for Rh 
recovery. The structured procedure is similar to the Rh recovery test 
method, where the process parameters are first defined then the actual 
process steps are described. 
Parameters 
1) Test is performed at room temperature (20.degree.-25.degree. C.); 
2) Flow rate, set pump to 1 mL/minute; 
3) Active Rh must be isolated from a hydroformylation process stream; 
4) The column containing the resin (material that will recover the Rh) has 
a diameter of 1 cm; 
5) The quantity of resin used is 4.0 grams; 
6) The balance of the column was filled with sand; 
7) Treat process stream that contains 1 to 1.5 column volumes of process 
stream (4 to 6 grams of process stream). The trials performed using a 
phosphorus ligand, e.g., a TPP based hydroformylation process stream 
contained 1 to 1.5 milligrams of Rh charged to the resin, while the trials 
performed using a different ligand based commercial hydroformylation 
process stream contained 1.7 to 3.6 milligrams of Rh charged to the resin; 
and 
8) The effluent from the column is isolated in three different fractions. 
Column Preparation 
1) Charged resin as a slurry in water; 
2) Activated resin by passing 10 grams of 5 wt % HCl(aq) in methanol; 
3) Pumped 10 grams degassed methanol across the column to remove impurities 
and to return the column effluent to a neutral pH (pH.multidot.6); 
4) Pumped 10 grams degassed heptane across column; 
5) Pump hydroformylation stream across column (4 to 6 grams at 250 to 600 
ppm Rh), collect the effluent in the process stream collection flask; 
6) Wash resin with 10 grams of degassed heptane, followed by a wash into 10 
grams of degassed methanol, collect the wash effluent in the solvent wash 
collection flask; 
7) Remove Rh from the column with 10 grams of 5 wt % HCl.sub.(aq) in 
methanol (pH&lt;0), followed by 10 grams of methanol; 
8) A second trial may be performed by returning to step three and repeating 
steps three through seven with a second fraction of hydroformylation 
process stream; and 
9) Analyze the three collected fractions (process stream, solvent wash, and 
recovered Rh) for the Rh content, using ICP emission spectroscopy. 
The experiments used a 1.5:1 or approximately a one to one ratio of grams 
of process stream to grams of ion exchange resin in the column. The 
elution flow rates (1 mL/min) and other conditions (e.g., room 
temperature) were kept constant unless otherwise noted. The following 
table lists the quantity of rhodium recovered using the different resins: 
TABLE I 
______________________________________ 
RESIN 
% Rh 
TYPE RESIN 
RECOVERED CONDITIONS BACKBONE ACTIVE GROUP 
______________________________________ 
Aromatic* normal silica gel aromatic 
&gt;95% sulfonic acid 
Propyl* normal silica gel propyl sulfonic 
86.6% acid 
Propyl* Faster silica gel propyl sulfonic 
98% elution acid 
rates 
CROSS-LINKED 
normal methyl and propyl sulfonate 
3-sulfopropyl propyl methacry- 
potassium salt 
1.6% late/TMPTMA 
methacrylate 
(salt) 
CROSS-LINKED 
normal methyl and propyl sulfonic 
3-sulfopropyl propyl methacry- 
acid 
35.6% late/TMPTMA 
methacrylate 
(acid) 
AMBERLYST** 
normal styrene/divinyl 
sulfonic acid 
7.0% benzene 
X1010 
AMBERLYST normal styrene/divinyl 
sulfonic acid 
13.8% benzene 
AMBERLITE** 
normal methacrylic sulfonic acid 
1% acid/divinyl 
IRP-169 benzene 
AMBERLITE normal styrene/divinyl 
iminodiacetic 
1% benzene acid 
IRC-718 
______________________________________ 
*Sold by J. T. Baker under BAKERBOND brand name 
**AMBERLYST and AMBERLITE are brand names of the Rohm and Haas Co. 
Using the procedure outlined above the Bakerbond aromatic sulfonic acid 
resin recovered &gt;95% of the active Rh. Amberlyst X1010 resin recovered 
13.8% of the active Rh and Amberlyst 15 recovered 7.0% of the Rh. 
As can be seen above, the sulfonic acid containing resins were found to be 
the most effective in binding active rhodium catalyst. Of these sulfonic 
acid containing resins, the aromatic sulfonic acid resin having a silica 
gel resin backbone gave superior results for preferentially absorbing 
active rhodium catalyst and impurities from hydroformylation process 
streams. It is believed that electronic and steric interactions between 
the resin and the catalyst affect the binding efficiency of the rhodium 
species to the active group of the resin. Thus resin backbones, e.g., 
silica gel backbone may have an effect upon the quantity of rhodium 
recovered. 
It was also discovered that the propyl sulfonic acid containing resin, 
although the most effective in binding rhodium, was not as effective in 
ultimately recovering the rhodium catalyst since a portion of the rhodium 
was not released during an acidic solvent wash at a pH below 4 and thus 
permanently bound to the resin. 
Additionally, the acidic cross-linked 3-sulfopropyl methacrylate shown in 
Table 1 above was developed as a resin useful in a continuous recovery 
process. It was not as effective, as the other resins tested. Thus, the 
binding properties of the above resins permit rhodium containing catalysts 
to be selectively bound and then released so that the catalyst can be 
recovered and the resin reused continuously. 
While the resins disclosed above are useful in the continuous rhodium 
recovery process of the present invention, it will be appreciated that 
other resins may be utilized in conjunction with the method as taught 
above. The resins, to be useful in the process, must meet the criteria 
that they selectively bind active rhodium catalyst tightly enough to 
permit the removal of impurities from a hydroformylation process stream 
containing active and inactive rhodium catalyst and impurities yet loosely 
enough to permit sequential removal of impurities and then active rhodium 
resin removal if the catalyst from the resin when desired. 
The four resin listed above, are all acidic ion exchange resins. The 
Amberlite resins do not appear to recover rhodium while the amberlyst 
resins recover a limited quantity of rhodium. The Bakerbond products 
recovered &gt;95% of the rhodium. 
After using the initial screening test, the following test method is used 
to indicate the ability of the resin to perform in a commercial process. 
The process parameters are first defined then the actual process steps are 
described. Any resin (material) that recovers greater or equal to 15% of 
the charged active rhodium using the following step-by-step process can be 
used in the process of the invention. 
Parameters 
1. Test is performed at room temperature (20.degree.-25.degree. C.) 
2. Flow rate, set pump to 2 mL/minute 
3. Rh must be isolated from a hydroformylation process stream 
4. The column containing the resin (material that will recover the Rh) has 
a diameter of 1 cm 
5. The quantity of resin used is 4.0 grams 
6. The balance of the column should be filed with an inert packing material 
such as sand or silica 
7. Treat process stream that contains 5 milligrams of Rh (20 grams of 
process stream containing a concentration of 250 ppm of Rh) 
8. If process stream contains more than 250 ppm of Rh dilute with butanal 
to achieve 250 ppm Rh, if process stream contains less than 250 ppm Rh 
strip aldehyde in stream to achieve 250 ppm Rh 
9. The effluent from the column is isolated in three different fractions 
Column Preparation 
1. Charge resin as a slurry in a suitable solvent (such as water or 
isopropyl alcohol) 
2. Activate resin by standard procedure as recommended by the resin 
manufacturer 
3. Pump 20 grams degassed isopropyl alcohol across the column to remove 
impurities and to return the column effluent to a neutral pH (pH&gt;6) 
4. Pump 20 grams degassed heptane across column 
5. Pump hydroformylation stream column (20 grams at 250 ppm Rh), collect 
the effluent in the process stream collection flask 
6. Wash resin with 10 grams of degassed heptane, followed by a wash with 10 
grams of degassed tetrahydrofuran, collect the wash effluent in the 
solvent wash collection flask 
7. Remove Rh from the column with 20 grams of 5 wt % HCl.sub.(aq) in 
isopropyl alcohol (pH&lt;0), followed by 10 grams of tetrahydrofuran and 20 
grams of 5 wt % HCl.sub.(aq) in isopropyl alcohol, collect in recovered Rh 
collection flask 
8. A second trial may be performed by returning to step three and repeating 
steps three through seven with a second fraction of hydroformylation 
process stream 
9. Analyze the three collection fractions (process stream, solvent wash, 
and recovered Rh) for the Rh content, using standard analytical methods 
(ICP is recommended) 
Table II sets forth the test results showing the quantity of rhodium 
recovered using the above method. 
TABLE II 
______________________________________ 
RESIN 
% Rh 
TYPE CONDI- RESIN 
RECOVERED 
TIONS BACKBONE ACTIVE GROUP 
______________________________________ 
Amberlyst 
normal styrene/divinyl 
sulfonic acid 
2.9% 
X1010 benzene 
J T Baker 
normal silica gel diamino group 
1.1% 
Diamino 
J T Baker 
normal silica gel sulfonic acid 
35.1% 
Propyl 
sulfonic 
acid 
J T Baker 
normal silica gel carboxylic acid 
38% 
Carboxylic 
Acid 
J T Baker 
normal silica gel Aromatic sulfonic 
39.9% 
Aromatic acid 
Sulfonic 
Acid 
______________________________________ 
Criteria for Selection of Resin 
1. The quantity of active organo-rhodium catalyst recovered from the resin 
must be at least 15% of the active organo-rhodium catalyst charged to the 
column 
It should be noted that for the above processes, while other process 
parameters did influence rhodium recovery, these parameters had less of an 
effect on the recovery process than the type of resin used. The elution 
rate is important. Therefore, slow flow rates of the solvents (e.g. 2-5 
mL/min for a resin contained in 1.times.10 cm column) are better than fast 
flow rates because the adsorption of Rh is not instantaneous. 
Alternate Rehydriding Methods 
An alternative method for rehydriding the active rhodium in small reactor 
28 is to pressurize reactor 28 with hydrogen gas and/or synthesis gas 
(H.sub.2 and CO) in the presence of an acid scavenger such as methyl or 
ethyl amines, pyrridine, hydrazine, etc., prior to filtering off the 
acid-base adduct or by-product stream in separator 30. This also will 
convert the (Phosphorous Ligand)nRh(I)Cl to (Phosphorous Ligand)nRh(I)H 
and capture the HCl acid with the acid scavenger as a byproduct. This is 
accomplished as follows: 
1) The active Rh catalyst is removed from the resin as the (Phosphorous 
Ligand).sub.n RhCl complex in a polar solvent such as alcohols (methanol, 
isopropyl alcohol), THF, toluene, xylene, acetone and methyl ethyl ketone 
at a pH below 4. 
2) An acid scavenger is added to the reactor 28 such as an amine 
(triethylamine, diethylamine, tripropylamine, dipropylamine) pyridine and 
hydrazine. 
3) Add Phosphorous Ligand (e.g., TPP) to the reactor 28. The preferred 
quantity of TPP is 10 to 30 moles of TPP per mole of Rh, although the 5 to 
200 moles of TPP per mole of Rh is acceptable. 
4) Pressurize reactor 28 e.g. to 200 psig with H.sub.2 and CO preferably at 
the same ratio as used in the hydroformylation process. 
5) This will produce hydrided active rhodium catalyst, e.g. (Phosphorous 
Ligand).sub.n RhH and Hcl with the HCl scavenged by the base. This is 
stream 46 in FIG. 1. 
6) Stream 46 in FIG. 1 filtered to remove the acid-base adduct produced by 
the scavenging of Hcl and produce stream 32. 
7) Add 2,2,4-trimethyl-1,3-pentanediol mono (2-methypropanoate) to the 
filtered solution and recycle stream 32. 
B. Rehydriding of Stream with Sodium Borohydride in an Alcohol 
Stream 26 containing active organo-rhodium catalyst complex and solvent is 
introduced into reactor 28. Stream 26 consists of primarily of acidified 
active catalyst such as (Phosphorous Ligand).sub.n RhCl and 
non-coordinated Phosphorous Ligand in the acidic solvent. Rehydriding can 
be accomplished by contacting stream 26 in reactor 28 with a sodium 
borohydride and ethanol mixture. This will neutralize acid and rehydride 
the catalyst producing sodium chloride. The rehydrided rhodium catalyst 
can be precipitated, washed to remove impurities, suspended in 
2,2,4-trimethyl-1,3-pentanediol mono (2-methypropanoate) and returned to 
reactor 10. 
C. Rehydriding with Hydrazine in an Alcohol 
Active organo-rhodium catalyst complex and acidic solvent are removed 
during regeneration as stream 26 and introduced into reactor 28. Stream 26 
consists of acidified active rhodium catalyst e.g. (TPP).sub.n RhX, X is 
the counter anion of the acid that was used to release the organo-rhodium 
catalyst from the resin, and non-coordinated TPP in the acidic solvent. 
Rehydriding can be accomplished by contacting stream 26 with excess 
hydrazine charged as a solution of 95 hydrazine in water, in reactor 28. 
This will neutralize the acid in the solution producing hydrazine 
hydrochloride, while converting the (TPP).sub.n RhCl to the active 
(TPP).sub.n RhH. The by-product can be separated from the solution by 
filtering, the reactivated rhodium can be precipitated, washed to remove 
impurities, suspended in 2,2,4-trimethyl-1,3-pentanediol mono 
(2-methypropanoate) and recycled to the reactor 10. 
D. Rehydriding with Hydrazine and Hydrogen Gas in Mixed Solvent 
Rehydriding of stream 26 can be accomplished by adding an aromatic solvent 
to Stream 26 and contacting it with hydrazine and hydrogen gas, in reactor 
28. This will neutralize the acid in the solution, e.g. if Hcl, it 
produces hydrazine hydrochloride, while converting the (TPP).sub.n RhCl to 
the active (TPP).sub.n RhH. The by-product can be removed from the 
solution by filtering, and the rehydriding rhodium catalyst can be 
precipitated, washed to remove impurities, suspended in 
2,2,4-trimethyl-1,3-pentanediol mono (2-methypropanoate) and returned to 
reactor 10. 
E. Rehydriding with Sodium Alkoxide in Alcohol 
Stream 26 is introduced into reactor 28. Rehydriding can be accomplished by 
contacting stream 26 with sodium alkoxides, introduced into reactor 28 as 
sodium alkoxides in alcohols. This will neutralize the acid in the 
solution producing sodium chloride and alcohol, while hydriding the 
catalyst. For example, with Hcl as the acid the (TPP).sub.n RhCl is 
hydrided to the active (TPP).sub.n RhH. The sodium chloride can be removed 
from the solution by filtering the rehydrided rhodium can be precipitated, 
washed to remove impurities, suspended in 2,2,4-trimethyl-1,3-pentanediol 
mono (2-methypropanoate) and returned to the reactor.