Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-12-18
2002-04-23
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S861000, C560S129000, C560S179000
Reexamination Certificate
active
06376723
ABSTRACT:
This invention relates to a carbonylation process, wherein formaldehyde or a derivative thereof is reacted with carbon monoxide in the presence of a catalyst system.
BACKGROUND OF THE INVENTION
The carbonylation of formaldehyde yields as its main and most desirable product (poly)glycolic acid, which acid can for example be easily esterified with an alcohol and then catalytically hydrogenated to produce ethylene glycol. Ethylene glycol (EG) is one of the most important of the commercially available glycols. It is predominantly used in antifreeze and in the production of polyesters. Presently, EG is commercially produced by the liquid phase hydration of ethylene oxide (EO), which in turn is produced by oxidation of ethene. The economy of the conventional process is highly dependent on the ethylene price. The dependence on ethylene as raw material has promoted the investigation of alternative EG production processes based on synthesis gas (syngas), which is a less expensive feedstock.
DuPont is the only company that actually operated a syngas based EG synthesis route in a commercial plant from 1940 to 1968. The commercial DuPont process used formaldehyde derived from syngas as raw material and sulphuric acid as the catalyst. In this process, formaldehyde was first carbonylated with carbon monoxide and water to hydroxyacetic acid (glycolic acid) at 200° C. and 700 bar. The glycolic acid was subsequently esterified with methanol to form methyl glycolate and water. The methyl glycolate was hydrogenated to EG with accompanying release of methanol. The DuPont process gave a 90% molar yield based on formaldehyde during the carbonylation step. Relevant DuPont patent publications are U.S. Pat. No. 2,152,852 (1939) and U.S. Pat. No. 2,285,448 (1942).
In U.S. Pat. No. 3,911,003 to Chevron (1975) there is disclosed a similar process for preparing glycolic acid by the reaction of formaldehyde with carbon monoxide (as such or in syngas) and water in the presence of HF at about 22-50° C. and 1000-2000 psig (about 6800-13800 pKa). Glycolic acid is obtained in 95% selectivity and at about 100% formaldehyde conversion. It is mentioned that the glycolic acid can be esterified with methanol and then catalytically hydrogenated to produce a mixture of ethylene glycol and diethylene glycol which is readily separated by distillation.
U.S. Pat. No. 4,087,470 to Chevron (1978) presents an alternative to the glycolic acid esterification step for producing ethylene glycol from formaldehyde, by using ethylene glycol instead of methanol. It defines an integrated process for preparing ethylene glycol by (1) contacting formaldehyde and syngas in the presence of HF to deplete the carbon monoxide from the syngas and simultaneously form glycolic and diglycolic acid, (2) contacting the acid product with ethylene glycol, diethylene glycol or a mixture thereof to produce the respective glycolates, (3) removing residual carbon monoxide from the carbon monoxide depleted syngas of step 1 to produce a hydrogen-rich gas, (4) hydrogenating the glycolates with the hydrogen-rich gas to produce the respective glycols, and (5) recycling a portion of the glycols to step 2.
The Chevron process for carbonylating formaldehyde represents an improvement over the DuPont process in that the required temperature is lower, but the pressure is still very high.
In the article of Lee, Kim, Lee and Kim, Carbonylation of formaldehyde over Ion Exchange Resin Catalysts. 1. Batch Reactor Studies, Ind. Eng. Chem. Res., 1993, vol. 32, pages 253-259, a similar process for acid-catalysed carbonylation of formaldehyde to glycolic acid and its esterification to obtain methylglycolate is disclosed. As acid-catalyst, several sulfonic acid resins, including NAFION NR-50, AMBERLYST 15 and AMBERLYST 36 were mentioned. As solvents 1,4-dioxane, acetic acid, methyl benzoate, methyl formate, methyl acetate, formic acid, methanol and methylene chloride were mentioned. It was found that except for acid solvents, all solvents showed better selectivity towards methylglycolate in the presence of water. Maximum methylglycolate yields of about 78% were obtained at a temperature of about 135° C. However, to obtain such a yield, a high initial CO pressure of 3500 psig (about 24100 kPa) was needed.
In U.S. Pat. No. 4,933,410 to Applied Immunosciences (1990) there is disclosed a method for functionalising polystyrene surfaces of labware by contacting polystyrene surfaces with an a-substituted N-hydroxymethyl acetamide compound, dissolved in tetramethylene sulfone (sulfolane), in the presence of a Lewis acid (including protonic catalysts), such as trifluoromethane sulfonic acid.
In U.S. Pat. No. 3,795,712 (1974) and U.S. Pat. No. 4,024,203 (1977), both to Institut Francais du Petrole, there are disclosed a hydrocarbon alkylation process and a mono-olefin oligomerisation process respectively, both in the presence of a liquid catalyst composition containing a Lewis acid or a Brønsted acid and a sulfone (such as sulfolane).
SUMMARY OF THE INVENTION
The present invention relates to a carbonylation process, wherein formaldehyde or a derivative thereof is reacted with carbon monoxide in the presence of a catalyst composition including:
a) an acidic compound with pKa value below −1,
b) a sulfone.
DETAILED DESCRIPTION OF THE INVENTION
It has now been found that by using a catalyst composition of an acid and a sulfone, the carbonylation of formaldehyde or a derivative thereof can be conducted under relatively mild reaction conditions.
The process according to the present invention can be used for the carbonylation of formaldehyde or a derivative thereof. A preferred group of derivatives of formaldehyde includes dimethoxy methane, dioxolane, trioxane (trioxymethylene) and the polymer para-formaldehyde. Formaldehyde and para-formaldehyde are particularly preferred. The carbonylation product, (poly)glycolic acid, can be used for producing ethylene glycol via the known steps of esterification and hydrogenation.
Another preferred group of derivatives of formaldehyde are the acetals and poly-acetals. Suitable acetals include the hemi-acetals. The dimethyl acetal of formaldehyde is preferred. The carbonylation product of the dimethyl acetal of formaldehyde, methoxy methyl acetate, can be an interesting chemical solvent, gasoline octane booster or diesel supplement. Polyacetal is a suitable acetal alternative to formaldehyde in the production of ethylene glycol as above.
The acidic compound to be used in the catalyst composition in the carbonylation process according to the invention has a pKa below −1, preferably below −2, when measured in water at a temperature of 18° C. Said acidic compound may be homogeneous or heterogeneous and can be any kind of Lewis acid or Brønsted acid.
The term “pKa” is a common symbol used to express the strength of an acid and is related to the dissociation constant for the acid in aqueous solution. The measurement and evaluation of pKa for a wide range of strong and weak acid types is reviewed in “The Proton: Applications to Organic Chemistry” by Ross Stewart, (1985), published by Academic Press, Inc. ISBN 0-12-670370-1.
Preferred homogeneous acids may suitably be chosen from the group of sulfonic acids. Preferably the homogeneous acid is an halogenated sulfonic acid of the R—SO
3
H type, wherein R represents an halogenated aliphatic or an halogenated aromatic group. An especially preferred halogenated sulfonic acid is triflic acid (trifluoromethylsulfonic acid).
The homogeneous acid can also be a combination of acids, such as a superacid. Suitable superacid systems include HFBF
4
and HSbF
6
.
Preferred heterogeneous acids are the strongly acidic ion exchange resins, all of which are of the sulphonic type. Examples of commercially available strongly acidic ion exchange resins of the sulphonic type are those known by the trade names AMBERLYST 15, AMBERLYST 38 W, AMBERLYST 36, AMBERJET 1500H, AMBERJET 1200H, (AMBERJET is a trademark of Rohm and Haas Company) DOWEX MSC-1, DOWEX 50W (DOWEX is a trademark of Dow Chemical Company), DELOXAN AS
Drent Eit
Mul Wilhelmus Petrus
Ruisch Bart Johan
Padmanabhan Sreeni
Price Elvis O.
Shell Oil Company
LandOfFree
Process for the carbonylation of formaldehyde does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the carbonylation of formaldehyde, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the carbonylation of formaldehyde will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2860520