CA1111056A - Preparation of bismuth-modified spheroidal malachite - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Spheroidal agglomerates of malachite crystals are pre-pared by bringing together solutions of a cupric salt, a bismuth salt and an alkali metal carbonate or bicarbonate to form a mix-ture containing amorphous hydrated copper carbonate, and then holding the mixture, without agitation, at a temperature of less than about 55°C.

Description

~: BACKGROIJND AND SUMMARY OF THE INVENTION
The method of producing 1,4-butynediol by the reaction of formaldehyde and acetylene using a copper acetylide complex as a catalyst :is, of course, well known and has been used for many years. It is also well known that this reaction produces cuprene, which tends to clog filters and affects the process adversely.

- One method commonly used to inhibit cuprene forma-tion during the reaction is to conduct it in the presence of ; 10 bismuth, either in elemental form or in the form of a bis-muth compoundO In Kirchner U.S. Patent 3,650,985, for example, it is demonstrated in Example 39 that bismuth oxycarbonate can be used as a cuprene inhibitor by mixing it, in the initial stage of the process, directly with the basic copper carbonate (malachite) used to form the copper acetylide catalyst. While bismuth used in this way does inhibit cuprene formation, it tends to separate from the catalyst after a time, which leads to unsatisfactory results.

One method of dealing with the separation of bis-muth from the catalyst is shown in Belgian Patent 825,446, according to which bismuth is uniformly dispersed in a malachite precursor, and subsequently in the copper acety-lide catalyst itself, by first preparing hydrated copper carbonate particles, nucleating and converting these particles to malachite by heating them, and then growing agglomerates of malachite containing bismuth oxycarbonate uniformly dispersed therein by adding solutions of a copper salt, a bismuth salt and an alkali metal carbonate to a water slurry of the malachite. This malachite is easily converted to a copper acetylide catalyst.

- 2 -~ 11li~56 While the bismuth compound in a catalyst thus pro-duced tends to stay in place, the catalyst is composed of ag-.:. .
glomerates of angular crystals which are degraded by attrition as the butynediol reaction proceeds, which interferes with its efficiency. L'''' This problem, as well as the others just mentioned, is minimized by the use of the malachite and copper acetylide ` catalyst produced according to this invention, whose agglome-rates are spheroidal and contain uniformly dispersed bismuth t 10 oxycarbonate. E
The spheroidal agglomerates of malachite can be made . .
according to the invention by first forming a mass of hydrated t copper carbonate by bringing together, with mixing, an aqueous .
solution of a cupric salt, an aqueous solution of a bismuth salt and an aqueous solution of an alkali metal carbonate or bicarbonate. This mixture is then held, without stirring or agitation, at a temperature of less than about 55C, whereupon the spheroidal agglomerates of malachite crystals form.
These agglomerates can, in turn, be converted to ` 20 copper acetylide complex by slurrying them in water and then ~`
- subjecting them to the action of acetylene and formaldehyde.
DETAILED DESCRIPTION OF THE INVENTION
The process of the present invention consists essen- ~
tially of: ~ -(A) forming amorphous gel-like hydrated copper carbonate by bringing together with mixing, t at a temperature less than about 55C, enough of (1) an aqueous solution of a cupric salt, (2) an aqueous solution of a bismuth salt, and

- 3 -.:

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` (3! an aqueous solution of an alkali metal carbonate or an alkali metal bicarbonate, to yield a mixture with a pH value of 5.5 to 7.5;
and then (B) holding the mixturle of (A), without agitation, at a temperature less than about 5SC.
Any water soluble cuprir salt can be used in the pro-cess of the invention. Illustrative are cupric nitrate, cupric chloride and cu?ric sulfate. Cupric nitrate is preferred ~- because of its solubility and availability.
Similarly, any water soluble bismuth salt can be used.
Illustra~ive are the nitrate, the oxycarbonate, the citrate, the sulfate and the phosphate. Bismuth nitrate is preferred, also because of its solubility and availability.
Of the alkali metal carbonates and bicarbonates which can be used, sodium carbonate and sodium bicarbonate are pre-~- ferred becuase of their low cost.
Each salt solution is prepared so that it contains as much salt as possible without it crystallizing from solution on standing or during use. The solutions are then brought to-gether in such proprotions that the pH of the resulting mixture is about 5.5 to 7.5, preferably 6.0 to 7Ø In the usual case, this pH range can be attained by the use of an appropriate amount of the alkali metal carbonate or bicarbonate solution.
The bismuth salt`is usually present in the resulting mixture at ~`~ a concentration of 1 to 10% by weight, of the copper content.
The so:Lutions can be brought together in any order, yenerally over a period of 20 to 60 minutes, and are then mixed by ~tirring or by agitation. In a preferred embodiment, a solution of the c:opper salt and the bismuth salt is prepared, and this is fed t:o a small heel of water, simultaneously with a S~ ~
solution of the alkali metal carbonate or bicarbonate, as shown in Example 1.
It is improtant that the solutions be brought to-gether in a vessel which has been cleansed of malachite nuclei by first rinsing it with dilute nitric acid~`
The resulting mixture is held at a temperature of just slightly about the freezing point of the medium to about 55C, preferably 35 to 50C, with stirring or agitation. An F
amorphous mass of gel-like hydrated copper carbonate forms l~
10 immediately. ~-The agglomerates of malachite are then prepared from the hydrated copper carbonate by holding the li~uid in which the carbonate is contained at about the same temperature as is used in the gel-formation step, without stirring or agitation of any kind. Carbon dioxide begins to evolve and agglomerates of malachite crystals form.
The malachite thus formed consists of spheroidal ag-glomerates of basic copper carbonate crystals. At least about 80% of these agglomerates are about 5 to 12 microns in the 20 longest dimension, as determined optically against a standard.
The agglomerates contain 1 to 4%, by weight, of uniformly dis-persed bismuth oxycarbonate, preferably 2 to 3%. "Uniformly c dispersed" means the oxycarbonate is evenly distributed through all of the agglomerate on a molecular scale.
The agglomerates then separated from the reaction mass by filtration, and washed free of salts with water. When higher concentrations of bismuth salt are used in preparing the agglomerates, it is desirable that residual gel and smaller agglomerates be removed by hydrocloning the reaction 30 mixture before the filtration step. A suitable apparatus for this step is the Dorr Clone*, made by Dorr-Oliver, Inc., of Stamford, Connecticut.
r denotes trade mark - These malachite agglomerates can be converted into copper acetylide catalyst by preparing a slurry of agglome-rates in water and then subjecting this slurry to the action of acetylene and formaldehyde. This procedure is described in more detail in Kirchner, U.S. Patent 3,650,985, beginning in column 5.
The copper acetylide complex produced in this way is in the form of spheoidal agglomerates containing uniformly - dispersed bismuth oxycarbonate, at concentrations which paral-lel that of the malachite from which the complex is prepared.
The complex can be used as a catalyst for the re-action of acetylene and formaldehyde to produce 1,4-butynediol.
The complex is used in the customary way and in the usual ; amounts, and no special techniques or precautions are necessary.
i Details for such use can be found in Kirchner U.S. Patent 3,650,985.
EXAMPLES
Example 1 In 100 ml of water were dissolved CU(NO3)2.3H~0 Concentrated HNO3 10 ml Bi(No3)3.5H2o 1.74 g ~he resulting solution was f~d, with stirring, over a 40 minute period, to 300 ml of water held at 35C. Enough saturated aqueous solution of Na2CO3 was added to keep the pH
of the æolution at 6.7 to 7.2.
Stirring was then stopped and the solution held at 35C. A blue gel filled the vessel; this gel contracted to 1/8 its original volume in about 2-1/2 h,ours to form spherical agglomerates of malachite crystals, which were then separated from the liquid by filtration, washed with water and then dried at 100C for 1 hour. This product was then hydrocloned to remove residual gel and small particles.
At least 80~ of these agglomerates were S to 12 microns in the longest dimension.

Exam~le 2 To a glass vessel were charged Malachite of Example 1 45 g Formaldehyde (37~ in 600 g water) CaCo3 2 g . . .
` A stream of acetylene containing 90~ by volume of nitrogen was passed through the vessel at a rate of 2 liters/minute.
The pressure within the vessel was held at 4 to 5 psig and the temperature of the reaction mass at 70 to 80DC. The car~on dioxide which formed was vented to the outside.
When carbon dioxide evolution stopped, the con- -tents of the vessel were cooled, removed from the vessel and washed with water.
The resulting copper acetylide complex was stored under water untii ready for use.

Example 3 To a reactor vessel were charged Copper-acetylide complex 45 g of Example 2 Formaldehyde (15% in 600 ml water) Acetylene was continuously passed through the vessel at a rate of 300 ml/minute, the pressure being maintained at about 5 psig. Enough of a 37% aqueous solution of formaldehyde .
~ 7 ~

was continuously fed into the vessel to maintain a formalde-hyde concentration of about 10% by weight. Similarly, enough of a saturated solution of sodium bicarbonate was continuously fed into the vessel to hold the pH of the con tents at 6.0 to 6.2. The product, 1,4-butynediol, was con-tinuously removed by filtration.
After 100 hours of continuous use, the catalyst was removed from the vessel and analyzed by X-ray diffrac-`~ tion scanning. No metallic copper was detected, indicating that the catalyst remained stable and useful.
Example 4 The process of Example 1 was repeated, using 5.8 gof bismuth nitrate instead of 1.74 g.
The resultin~ spheroidal agglomerates of malachite contained 4~, by weight, of uniformly dispersed bismuth oxycarbonate.
These agglomerates can be converted to copper acetylide catalyst as shown in Example 2, which in turn can be used in the procedure shown in Example 3 to form 1,4-butynediol.
The application is a division of copending Application Serial No. 284 012, filed 1977 August 3.

Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A copper acetylide complex produced by a process consisting essentially of subjecting a spheroidal agglomerate of basic copper carbonate crystals, as a slurry in an aqueous medi-um, to the action of formaldehyde and acetylene, said basic cop-per carbonate crystals having been produced by a process consisting essentially of (A) forming amorphous gel-like hydrated copper car-bonate by bringing together with mixing, at a temperature less than about 55°C, enough of (l) an aqueous solution of a cupric salt, (2) an aqueous solution of a bismuth salt, and (3) an aqueous solution of an alkali metal car-bonate or alkali metal bicarbonate, to yield a mixture with a pH value of 5.5 to 7.5;
(b) holding the mixture of (A), without agitation, at a temperature less than about 55°C, 80% of said agglomerates being about 5 to 12 microns in the longest dimension and containing 1 to 4%, by weight, of bismuth oxycarbonate.

2. In the production of 1,4-butynediol by reacting acetylene and formaldehyde in the presence of a copper acetylide catalyst, the improvement of using as the catalyst, the complex of Claim 1.