Ethynylation catalyst and method of making same

#The present invention is directed to a novel catalyst and method of preparing same for use in the catalytic ethynylation of formaldehyde, known as the Reppe reaction.

#Since the time of publication of German Pat. No. 725,326, various catalysts have been disclosed for the synthesis of butynediol from formaldehyde and acetylene, known as the Reppe ethynylation reaction. Suitable catalysts have proved to be acetylides of heavy metals, especially copper, which can be obtained from reacting acetylene with the suitable heavy metal compound. In a broader sense, the heavy metal compounds are also described as catalysts because of the fact that the actual catalyst, that is to say the acetylide of the heavy metal, is formed directly on passing acetylene into a suitable reaction mixture which contains the heavy metal compound as a “catalyst precursor” and therefore as a rule the manufacture of the catalyst merely entails manufacturing a suitable heavy metal compound. Accordingly, the use of a particular heavy metal compound of this type is regarded as the actual invention in the text, which follows.

#Copper compounds are known to be particularly suitable heavy metal compounds for the above purpose; they include, copper carbonate, copper phosphate, copper formate, copper acetate, copper-(II) chloride, copper-(I) chloride, ammoniacal copper sulfate, copper silicate and copper oxide. These compounds can be used unsupported or may be supported on carriers.

#FIG. 1 is an image of the inventive catalyst using Scanning Electron Microscopy coupled with Energy-Dispersive Spectroscopy (SEM-EDS).

#FIG. 2 is an image of the prior art catalyst using Scanning Electron Microscopy coupled with Energy-Dispersive Spectroscopy (SEM-EDS).

#FIG. 3 is an SEM image at a higher resolution of the inventive catalyst.

#Preparation of the Catalyst

#The siliceous particles generally will have an average diameter of from about 5 to 60 microns, preferably from about 10 to 30 microns. The carrier particles are first added to water in a precipitation vessel. An acidic solution is made up of a water soluble copper salt or a mixture of copper and bismuth salts in a separate vessel. A non-limiting example of a particularly useful water soluble salt is the nitrate salt. A basic solution is made up with NaOH also in a separate vessel. The temperature of the solutions are set at the precipitation temperature which is held constant throughout the precipitation process with a value anywhere from about 30° C. to about 90° C. The acid mixture and the sodium hydroxide solution are simultaneously added to the vessel containing water and the siliceous carrier particles. This simultaneous addition of the two streams is to ensure consistency in the precipitation of the hydroxides and the proper coating of the support. The precipitation is carried out at a constant pH of about 6 to about 10. During precipitation, the flow of the acid solution is kept constant while the flow of the NaOH solution is adjusted to keep the precipitation pH constant. The time of precipitation may be anywhere from 15 mins to 120 mins. Usually the time is about 60 mins to about 90 mins. After the precipitation step, the precipitate may be aged for a short time, about 15 mins to about 120 mins; although it has ben found that it is not imperative to age the precipitate in order to make a good catalyst. The precipitate is filtered, washed, and dried. The dried material is calcined in air. The calcination temperature may vary between 250 to about 550° C.

#Catalyst Composition