Note: Descriptions are shown in the official language in which they were submitted.
1089876
BAC~(Gl~OUND OF THE INVENTION
2 ~he procsss of this invention is used to prepare
3 ethylene glycol. ~ore particularly, the process prepa-es
4 ethylene glycol in on~ step from carbon ~ono~ide, hydrogen and
S for~aldehyde under ~oderate reaction condit.ons using a catalyst
6 co~prising rhodium or a rhodiu~ compound.
7 Ethylene glycol is an i~portant industrial alcohol
8 kno~n pri~arily for its use as an organic solvent and non-
9 volatile antifreeze or coolant. It is currently produced by a
variety of ~ethods. On a commsrcial scale ~ost ethyleDa glycol
11 is produced by hydrolysis of ethylene oxide with dilute sulfuric
12 acid, or ~ith wa~er, at high temFerature.
13 200C
14 ~CH2)zO + HzO ~ HOCH2CH20H
In yet another process ethylene glycol is produced by
16 the high temperature, bigh pressure reaction of carbon ~onorid~
17 and hydrogen. For eYa~ple, Ger~an Patent 2,426,~95 describes a
18 process for producing sthylene glycol and ~ethanol by the netal-
19 carbonyl-ca~alyzed reaction of hydrogen and carbon ~onoside at
high Fressures and tecperatures.
21 20,000 psi
22 3C0 ~ 5H2 ~ HOC~2CH20H ~ CH30H
23 220C
24 U.S. Patsnt 2,451,333 granted October 12, 1948 and
Gsroan Patent ~75,802 illustrate the conventio~al t~o-step
26 hydrofor~ylation and reduction of for~aldehyde. According to the
27 disclosures, hydrofor~ylation of for~aldehyde using a cobalt
28 catalyst yields a ~ixture of acetals and acetaldehyde, ~hich can
29 be reduced to ethylene glycol and ethylene glycol ethers. ~en
the reaction is carried out in an alcohcl solve~, the ~a~or
31 product is the glycol ether.
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10~9876
1 The prior art has relied upon harsh reaction condition
2 or ~ultiple step processes to prepare ethylsne glycol.
3 Accordingly, a one-step process ~hich can be conducted under
4 ~oderate conditions is desirable.
SUMMARY OF THE IN~ENTION
6 It has no~ been discovered that ethylene glycol can be
7 produced by contacting for~aldehyde, carbon mono~ide and hydrogen
8 in the pres~nce of an alcohol solvent and a catalyst co~prising a
9 rhodiu~ co~pound at a temperature af f ro~ aDou~ 100C to about
200C and a pressure of from about 1000 psi to about 10,000 psi.
11 Ethylene glycol is readily separatea from the reaction product
12 ~i~ture.
13 DETAIL13D DESCRIPTION OF $HE INVENTION
14 The process of this in~ention provides a ons-step
process for preparing ethylene glycol under noderate reaction
16 conditions. The process is based upon the finding that carbon
17 ~onoside, for~aldehyde and hydrogen can be co~bined under
18 oderate reaction conditions to produce ethylene glycol using a
19 catalyst co~prising a rhodium co~pound. ~y-products include
~ethanol and glycol ethers.
21 Carbon ~onoxide, hydrogen and formaldehyde are read~ly
22 available from numerous co~ercial sources. The nolar ratios of
23 these reactants ~h~ch are suitable for use in the process of this
24 in~ention ~ll vary depending upo~ the reaction conditions.
However, for general guidance, accepta~le ~olar ratios of
26 for~aldehyde to carbon nonoYide to hydrogen range fron about
27 1:20:1 to about 1:1:20, ~ithin this range, ratios of fro~ about
28 1:20:1 to about 1:1:10 have been found to provide a preferred
29 process.
In practice, the carbon ~onoYide and hydrogen reactants
31 ~ay be pro~ided as a synthesis g~s strea~ ~hich is passed either
32 co-currently or counter-currently to the for~aldehyde reactant.
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1()~9876
1 In a preferred continuous e~bodi~ent a synthesis gas -~treau
2 couprising carbon aono~iae and hydrogen is passed counter-
3 currently to a for~aldeh~de strea- in cascade fashio~ so that the
4 carbon uonoxide is re~cted out of the up~ard flowing ~trear
Rhodium is the catalyst for this process It uay be
6 used in either the ele~ental rhodiu- etal or as a rhodiu~-
7 containing co~pound. Rhodiuu es~sts in five oxidation states
8 ranging fro~ the zero state to tbe tetraEositive state. Of the
9 positive oxidation states erhibited, the tripositive st~te is the
~ost stable. Accordingly, the tripositi~e rhodiu- co~pounds are
11 pref~rred. The o~des, hallaes and ~ulfates are exa-plos of
12 suitable rhodlu- trlpo~itlve co-pou~ds. The halo ana cyano
13 co~pound~ aDa the a~ine co~pleres are also acceptable sources of
14 rhoaiu-
Rhodlu~(III) oside, Rh203 is an especially preferred
16 rhodium co~pound. It 18 formed ~hen po~dered rhodiun etal is
17 heat~d in air ~bove 600C. Slo~ addition of al~ali to solutions
18 of tripositive rhodiu~ results in the precipitation of the ~ello~
19 hydrate Rh203-5H20, ~hich i8 also a preferred rhodiun source.
Anionic coDpleses of tripo~iti~e rhodiua ~lth all t~e
21 haloqen~ are acceptable. Tho~e ~ith fluorine, chlorine, and
22 bro~ine being particularly preferr6d. The anhydrous rhoalu-
23 trihalides are repre~o~tative halo co-pounds. Th~y are obtainea
24 by appropriate dir~ct union of the ele~ents. The iodide can also
be prepared by precipitation fro~ agueous solutioD. Tbe
26 trifluoride is 8 dark red substance, practically ~nert to ~ater,
27 acids and bases. The trichloride, as prepared by direct union,
28 t s also red and is insoluble in ~ater and acids. Evaporation of
29 a solution of r~odiuJ~III) oxide hydrate in hydrochloric acid
yields RhCl3-4H20. Re~oval of the vater of crystallization at
31 180C in a hydrogen chloride at~osphere gives an anhyarous
..
1089876
1 trichloride which is water-solu~le; heating of this latter
2 ~aterial to higher te~peratures con~erts it ~o the ~ater-
3 ~nsoluble for~
4 The rhodium sulfate hydrates are pr~ferred sulfates.
Th~ best kno~n are Rh2(SO~)3-14H2O and Rh2(SO~)3-6H2O The
6 for~çr is a yello~ ~aterial obtained by dissolving the oxide
7 hydrate in cold dilute sulfuric acid and crystallizing by
8 evaporation in vacuo at 0; the red heYahydrate is prepared by
9 evaporating a~ agueous solution o~ the 14-hydrate to dryness at
100C. Pro- aqueous solutions of the 14-hydrate all the sulfate
11 i5 i~ediately precipitated by addition of barium ion.
12 Cationic auine co~plexes of rhodiu~(III) aro also
13 sultable sources of rhoaiu~. Representative co~pound types
14 include, aDong oth~rs, ~Rh(NH3)~]XJ, ~h~NH3)3~X3,
tRh (~3) ~ (H2O)]X3~ and [Rh~NHJ)sF ]X2 (R=nonovalent acid radical
16 or OH- group) wherein X is a suitable anion, for esa~ple halide.
17 In a preferred embodi~ent, the catalyst also co~prises
18 a cobalt carbon~l. The ter~ "cobalt carbonyl" is used in the
19 conventional se~se to include cobalt co-pleses vith carbon
~onox$ds. Suitable carbonyls ~ay be either pure carbonyls
21 ~herein carbon ~onoxide for~s a ~table co~pl~Y ~ith the lo~est
22 oxidation state of cobalt, or cobalt car~onyls bound to an
23 add~tional ~oiety ~uch as a halide or hydride. ~hus, carbon
24 ~onoxide acts as either a ~onodentate liga~d or a divalent
bridging group. Suitable cobalt carbonyls can be ~oDon~ric,
26 di-eric, or pol~eric.
27 In general, cobalt carbonyls suitable for us~ as
2~ catalysts in the process of this invention are of the foraula
29 Co ~CO) D (X) 1-
_
1089876
1 ~herein X is an anionic ligand bcund to the cobalt ion, n is l to
2 6, ~ is 0 to 6, and n~m is 3 to 6. The coordination number of
3 the cobalt ion is rspreseDted by n~, and the valence or
4 o~idation state of the cobalt Doiety is represented by ~. This
for~ula depicts only the e~pirical composition ~h~ch may also
6 exist in di~eric or polyneric form. Cobalt octacarbonyl is an -
7 especially preferred catalyst. Ihe cobalt carbonyl coupound can
8 be for~ed in advance and introduced into the reaction zone, or,
9 it ay be for~ed in situ fro~ a suita~le precursor. For exa~ple,
coC03 has been found tc be a precursor for cobal~ carbonyls under
11 the conditions of this process.
12 Effecti~e catalyst concentrations will ~ary depending
13 upon the reaction conditions e~ployed. In ge~eral, the process
14 can be carried out in the presence of a catalyt~cally effecti~e
amount of a catalyst co-prising rhodium. Ths rëaction starts
16 readily at catalyst concentrations of only 0.3 ~elqht %, although
17 e~en s~all quantities are effecti~e. Ihe ~asi~u~ concentrat~on
1~ ~ay go as high as 10 weight %. Ho~ever, in practice, econouic
19 con~iderations will lirit the concentration as no appreciable
ad~antages are gained by concentrations above about 5 ~eight %.
21 Typical catalyst concentrations ~ill range from about 0.1 to
22 about S ~eight S, preferably fron about 0.3 to about 3 ~elght S.
23 ~here 'he catalyst also co~prises a cobalt carbonyl, the relati~o
24 ~eight proportion of cobalt car~onyl to rhodiu~ ls not critlcal,
but ~ill typically raDge fron abcut 1:10 to about tO~
~; 26 The tenperature of reaction is relativel~ nild.
j~ 27 Te~peratures as lo~ as 100C are acceptable. In general, the
28 process is carr$ed out at te~peratures fror about 130C to a~out
29 200C. ~igher temperatures do not significantly iapro~ the
reaction rate, ~hile lo~er tsmperatures appreciably decrease the
31 reaction rate.
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~08987~
1 The reaction is carried out under ~oderate pressure
2 In ge~eral, the overall pressure will nct greatly esceed the
3 partial pressure of carbon ~onoside and hydrogen ~hich are by far
4 the ~ore ~olatile of the reactants Pressures froe about 1000
psig to about 10,000 psig are suitable At lo~er pressures, the
6 rats of r~action is relatively slov, ~hile at higher pressures,
7 no appreciable advantage is o~tained Preferred pressures range
8 fro- about 1000 psig to about 5000 psig At higher tenperaturQs
9 the cobalt carbonyl ~ay lose sta~ility conseguentl~ reducing the
yield of glycol and glycol ethers In order to direct the
11 reaction to~ard increasing yields, higher partial pressures of
12 carbon uonoxide and hydrogen are employ~d.
13 The residence ti~e required for the reaction to reach
14 co~pletion ~ay range fro- a fe~ ~inutes to sever~l hours,
depending upon the concentration of reactant and reaction
16 conaitions. In general, a residence ti-e of frou about 1 hr to
17 about 5 hrs ~ill be nece~sary to reach coopletion under preferred
18 reaction conditions. In practice it ~ay be advantageous to
19 continuously recover product there~y driving the reaction to~ard
production of glycol and ether. Coupletion is defined as th~
21 point at ~hich the anount of for~aldehyde converted to prod~ct as
22 a fuDction of ti~e does not appreciably increase
23 The process ~ay be carried out in the presence of a
24 801~ent. Esa~ples of organic liguids suitable for use as
solvents incluae ethers such as tetrah~drofuran, diethyl ether
26 and the li~e; and alkanols such as etha~ol, oethanol, 2-
27 ethylhesanol and the li~e.
t~ 28 The follo~ing Esa~ples further illustrate practice of
t 29 the process of this iDvent~on. Ihe E~aoples are represen*ati~e
and are not i~te~ded to li-it the inve~tion. Those fa-iliar ~ith
31 the art vill readily perceive ~odifications of t~e process in
32 vie~ of the Esanples
108987~
1 EXA~ELES
2 E~a~Ple I
3 A 300 cc Autoclave Engineers MagnedriYe Autoclave Yas
4 charged vith 16 g of paraformaldehyde, 50 g of ~ethanol, 2 g of
cobalt car~onyl [ C2 (CO) ~ ] and 0.1 g of N-(carboYy-ethyl)-N~-(2-
6 hydroYyethyl)-N,Nl-ethylenediglycine. The reaction ~as run at
7 180C for 2.5 hours using 67~ H2~33% C0 at 2800 psig. Vapor
8 chro-atographic analysis ~ith an internal standard sho~ed the
9 proauct to contain 6.3 g total of 2-~etho~yethanol and ethylene
glycol. This a~ounts to a 16~ yield based on the charged
11 for-aldehyde.
12 gxauDle II ~ -
13 The autocla~e used in Bsa~ple I ~as ch~rged ~lth 16 g
14 of parafor~aldehyde, 50 9 of ethanol and 0.2 g of ah2oJ-5H~o.
The reaction ~a~ run ~ith 67~ H2~33~ C0 at 3300 ps~g and 150C
16 for 2 hours. The product contained 2. e g (8.8~ yield) of
~7 ethylene glycol.
18 _~auPle III
19 ~he autocla~e used in Exa~ple I ~as chargea ~ith 16 g
of parafor~aldehyde, 50 g of ethanol, 0.2 g of cobalt carbonyl
21 and 0.5 g of Rh203-5H20. The reaction ~as run ~ith 67S ~2~33S C0
- 22 at 3103 p8ig and 150C for 5 hours. The product containea 4.1 g
23 of ethyleno glycol and 9.7 g of 2-ethoYyethanol for ~ co-blned
24 yiel~ of 35~ on tbe charged for-~ldehyae.
~x~4Ple IV
26 T~e autocla~e used in E~a-ple I ~as charged ~ith 16 g
27 of parafor~aldehyde, 50 g of eth~nol, 1 g of cob~lt carbon~l and
Z8 0.2 g of Rh203-5H20~ The reaction ~as run ~ith 67X H2/33~ C0 at
29 2700 psig and 13~C for 3 hours. The product containea 1.8 g of
ethylene glycol (5.7X yi-ld) and 4.7 g of 2-etho~yethanol (10.2%
31 ~eld).
:
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~01~9876
E~auLle V
2 The autoclave used in Esa~ple I ~as charged ~th 50 g
3 of oethylal, 0.2 g of cobalt car~onyl and 0.2 g of Rh2O3-5H20.
4 The reaction ~as run ~ith 67~ H2~33~ C0 at 3000 psig and 150C
for 3 hours. The product ~ontained 14 ~ total of 2-~etho~y-
6 ethanol ana ethylene glycol. This corresponds to a 30% yield
7 based on charged ~ethylal.
8 EYa~Ple VI
9 The autoclave used in E~anple I vas charged ~ith S0 g
of ~ethylal, 0.2 g of cobalt carbonyl and 0.2 g of Rh203-5HzO.
11 The reaction ~as run ~ith 67% H2~33~ C0 at 2900 psig and 180C
12 for 4.5 hours. The product contained 12.2 ~ total of 2-aethos~-
13 ethanol and ethylene gl~col for a yield of 24~.
14 Esaaples I through VI sho~ that the cobalt carbonyl-
Rh203-5BtO cat~lyst cc-binat~on gives better yields of ethylene
16 glycol and ethylene glycol ether than RhzO3-5BzO or cobalt
17 carboDyl aloDe us~ng a 67% H2/33~ C0 s~nthesis gas.
18 EsauDle y~I
19 The autoclave used in ~xa-ple I ~as charged ~ith 16 g
of parafor~aldehyde, 50 g of ethanol and 1 g of cobalt c~rbonyl.
21 The reaction vas run ~th S0~ H2/50% C0 at 3000 psig ana 180C
22 for 2 hours. The product contained 1 g of ethylene glycol ana 5
23 g of 2-ethoxrethanol for a conbined 14~ y~eld.
24 ~xa~le VIII
The autocla~e used in Esa-ple ~ ~as charged ~tb ~6 g
26 of parafor~aldehyde, 50 g of ethanol and 0.2 g of Rh2O3-5~2O.
27 The reaction ~as run ~ith 50% B2~50% CO a~ 3000-3500 psig and
28 130C for S hours and another 6.5 hour at 3000-3300 psiq and
29 150C. The product contained 2.9 q (9S yield) of ethylene
gl~col.
_ g _
- 108g876
1 E~amPle IX
2 The autoclave used in E~ample I was charg~d with 16 g
3 of par~or~aldehyde, 50 g of ethanol, 0.5 g of cobalt carbonyl
4 and 0.2 g of Rh2O3-5H 2- The reaction was run ~ith 50% ~2/5% C
at 3000 psig and 150C for 3 hours. The produc~ contained 1.6 g
6 of ethylene glycol and 4.7 g of 2-etho~yethanol for a co~bined
7 ~ield of 15.1~.
8 ~xa~ole X
9 A 300 cc Autoclave Engineers ~agnedri~e Autoclave vas
10, charged with 16 g of parafor~aldehyde, 50 g of ethanol, and 0.2 g
11 of Rh2O3-5HzO. ~he autocla~e was heated for 2 hours at 150C and
12 at a pres~ure of 3300 psig us~ng 67S Nz/33S CO. Vapor
13 chroDatographic analysis sho~ed the product contained 2.8 g
14 (8.8%) ethylene glycol and 12.14 g of ~ethanol.
tS Exa~P~e XI
16 The autoclave u~ed in Example X ~as charged wlth 16 g
17 of paraforo~ldehyde, 50 g of ethanol and 0.2 g of Rh20~-5~20.
18 The reaction was run ~ith 50~ ~2~5~ CO at 3000-3500 psig and
19 130C for 5 hours and another 6.5 hours at 3000-3300 pstg and
150C. The product contained 2.9 g ~9% yield) of ethylene g~ycol
21 and 2.9 g (18~ yield) of methanol.
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