GB1579039A

GB1579039A - Production of basic copper carbonate crystals

Info

Publication number: GB1579039A
Application number: GB3298277A
Authority: GB
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1976-08-05
Filing date: 1977-08-05
Publication date: 1980-11-12
Also published as: CA1096134A; FR2366299A1; DE2735465A1; IT1085695B; NL7708642A; JPS6125037B2; JPS5340700A; FR2366222A1; FR2366222B1; FR2366299B1; DE2735465C2

Description

(54) PRODUCTION OF BASIC COPPER CARBONATE CRYSTALS (71) We, E. I. DU PONT DE NEMOURS AND COMPANY, a corporation organised and existing under the laws of the State of Delaware, located at Wilmington, State of Delaware, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: 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 formation during the reaction is to conduct it in the presence of bismuth, either in elemental form or in the form of a bismuth compound.

In 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 bismuth 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 acetylide 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.

While the bismuth compound in a catalyst thus produced tends to stay in place, the catalyst is composed of agglomerates of angular crystals which are degraded by attrition as the butynediol reaction proceeds, which interferes with its efficiency.

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 agglomerates are spheroidal and contain uniformly dispersed bismuth oxycarbonate.

The invention thus provides a process for producing spheroidal agglomerates of basic copper carbonate crystals containing uniformly dispersed bismuth oxycarbonate, comprising: ( forming amorphous gel-like hydrated copper carbonate by bringing together in aqueous solution with mixing, at a temperature less than 55"C, a cupric salt, a bismuth salt and 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 mixture of (A), without agitation, at a temperature less than 55"C.

These agglomerates can, in turn, be converted to copper acetylide complex by slurrying them in water and then subjecting them to the action of acetylene and formaldehyde.

Any water soluble cupric salt can be used in the process of the invention. Illustrative are cupric nitrate, cupric chloride and cupric sulfate. Cupric nitrate is preferred because of its solubility and availability.

Similarly, any water soluble bismuth salt can be used. Illustrative 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 preferred because 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 together in such proportions that the pH of the resulting mixture is 5.5 to 7.5, preferably 6.0 to 7.0. 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 solutions can be brought together in any order, generally over a period of 20 to 60 minutes, and are then mixed by stirring or by agitation. In a preferred embodiment, a solution of the copper salt and the bismuth salt is prepared, and this is fed to a small heel of water, simultaneously with a solution of the alkali metal carbonate or bicarbonate, as shown in Example 1.

It is important that the solutions be brought together 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 above the freezing point of the medium to 550C, preferably 35C to 500C, with stirring or agitation. An amorphous mass of gel-like hydrated copper carbonate forms immediately.

The agglomerates of malachite are then prepared from the hydrated copper carbonate by holding the liquid 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. Formation is ordinarily complete in about 1 to 3 hours.

The malachite thus formed consists of spheroidal agglomerates of basic copper carbonate crystals. At least about 80% of these agglomerates are generally about 5 to 12 microns in the longest dimension, as determined optically against a standard. The agglomerates generally contain 1 to 4 %, by weight, of uniformly dispersed bismuth oxycarbonate, preferably 2 to 3 %.

"Uniformly dispersed" means the oxycarbonate is evenly distributed through all of the agglomerate on a molecular scale.

The agglomerates are 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 mixture before the filtration step. A suitable apparatus for this step is the Dorr Clone, made by Dorr-Oliver, Inc., of Stamford, Connecticut.

These malachite agglomerates can be converted into copper acetylide catalyst by preparing a slurry of agglomerates in water and then subjecting this slurry to the action of acetylene and formaldehyde. This procedure is described in more detail in U.S. Patent 3,650,985, beginning in column 5.

The copper acetylide complex produced in this way is in the form of spheroidal agglomerates containing uniformly dispersed bismuth oxycarbonate, at concentrations which parallel that of the malachite from which the complex Is prepared.

The complex can be used as a catalyst for the reaction 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. Details for such can be found in U.S.

Patent 3,650,985.

EXAMPLES Example I In 100 ml of water were dissolved Cu(NO3)2.3R2O 95 g Concentrated HNO3 10 ml Bi(NO3)3-5H20 1.74 g The resulting solution was fed, with stirring, over a 40 minute period, to 300 ml of water held at 35"C. Enough saturated aqueous solution of Na2CO3 was added to keep the pH of the solution at 6.7 to 7.2 Stirring was then stopped and the solution held at 350C. A blue gel filled the vessel; this gel contracted to 1/8 its original volume in about 2-1/2 hours to form spherical agglomerates of malachite crystals, which were then separated from the liquid by filtration, washed with water and then dried at 1000 C for 1 hour. This product was then hydrocloned to remove residual gel and small particles.

At least 80% of these agglomerates were 5 to 12 microns in the longest dimension.

Example 2 To a glass vessel were charged Malachite of Example 1 45 g Formaldehyde (37% in 600 g water) Cacao3 2g A stream of acetylene containing 90 who 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 700 to 80"C. The carbon dioxide which formed was vented to the outside.

When carbon dioxide evolution stopped, the contents of the vessel were cooled, removed from the vessel and washed with water.

The resulting copper acetylide complex was stored under water until 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 was continuously fed into the vessel to maintain a formaldehyde concentration 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 contents at 6.0 to 6.2. The product, 1,4butynediol, was continuously removed by filtration.

After 100 hours of continuous use, the catalyst was removed from the vessel and analyzed by X-ray diffraction 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 g of bismuth nitrate instead of 1.74 g.

The resulting 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.

WHAT WE CLAIM IS: 1. A process for producing spheroidal agglomerates of basic copper carbonate crystals containing uniformly dispersed bismuth oxycarbonate, comprising: (A) forming amorphous gel-like hydrated copper carbonate by brining together in aqueous solution with mixing, at a temperature less than 55"C, a cupric salt, a bismuth salt and 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 mixture of (A), without agitation, at a temperature less than 55"C.

2. A process as claimed in claim 1 in which the cupric salt is cupric nitrate, the bismuth salt is bismuth nitrate and the alkali metal carbonate is sodium carbonate.

3. A process as claimed in claim 1 or claim 2 in which the temperature in steps (A) and (B) are 35 to 500C.

4. A process as claimed in any one of the preceding claims in which step (A) comprises mixing an aqueous solution of the copper salt and the bismuth salt with an aqueous solution of the alkali metal carbonate or bicarbonate.

5. A process as claimed in claim 1, substantially as described herein in Example 1 or Example 4.

6. A spheroidal aggomerate of basic copper carbonate crystals when produced by a process as claimed in any one of the preceding claims.

7. A process for the formation of a copper acetylide complex comprising subjecting basic copper carbonate as claimed in claim 6, as a slurry in an aqueous medium, to the action of formaldehyde and acetylene.

8. A process as claimed in claim 7, substantially as described herein in Example 2.

9. A copper acetylide complex when prepared by a process as claimed in claim 7 or claim o

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. contracted to 1/8 its original volume in about 2-1/2 hours to form spherical agglomerates of malachite crystals, which were then separated from the liquid by filtration, washed with water and then dried at 1000 C for 1 hour. This product was then hydrocloned to remove residual gel and small particles. At least 80% of these agglomerates were 5 to 12 microns in the longest dimension. Example 2 To a glass vessel were charged Malachite of Example 1 45 g Formaldehyde (37% in 600 g water) Cacao3 2g A stream of acetylene containing 90 who 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 700 to 80"C. The carbon dioxide which formed was vented to the outside. When carbon dioxide evolution stopped, the contents of the vessel were cooled, removed from the vessel and washed with water. The resulting copper acetylide complex was stored under water until 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 was continuously fed into the vessel to maintain a formaldehyde concentration 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 contents at 6.0 to 6.2. The product, 1,4butynediol, was continuously removed by filtration. After 100 hours of continuous use, the catalyst was removed from the vessel and analyzed by X-ray diffraction 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 g of bismuth nitrate instead of 1.74 g. The resulting 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. WHAT WE CLAIM IS:

1. A process for producing spheroidal agglomerates of basic copper carbonate crystals containing uniformly dispersed bismuth oxycarbonate, comprising: (A) forming amorphous gel-like hydrated copper carbonate by brining together in aqueous solution with mixing, at a temperature less than 55"C, a cupric salt, a bismuth salt and 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 mixture of (A), without agitation, at a temperature less than 55"C.

10. A process for the production of 1,4-butynediol comprising reacting acetylene and formaldehyde in the presence of a copper acetylide complex as claimed in claim 9.

11. A process as claimed in claim 10, substantially as described herein in Example 3.

12. 1,4-Butynediol when produced by a process as claimed in claim 10 or claim 11.