HU195177B - Process for producing hexylene glycol - Google Patents

Abstract

Diacetone alcohol is hydrogenated at 100-140 deg. C at hydrogen pressure under 6 bar in the presence of 1-10% w/w Raney-nickel catalyst, which is impregnated with 0.1-5% chromium and/or molybdenum.

Description

The present invention relates to the catalytic preparation of 2-methylpentane-2,4-diol (hexylene glycol) from diacetone alcohol.

Hexylene glycol is prepared from diacetone alcohol by catalytic hydrogenation thereof. The most commonly used catalysts are copper chromium or supported nickel (H.Adkins and

R. Connor: J.A.C.S. 53, 1091 and 52, 4549). During the hydrogenation, these catalysts must be used at 150 ° C and 100-175 bar hydrogen pressure. High pressure means well-known technical and economic disadvantages. The high temperature is also unfavorable because it inevitably results in a smaller or greater decomposition of the diacetone alcohol, which, in addition to the economic disadvantage, also results in side reactions that require its rectification to produce high purity hexylene glycol.

One way to overcome the disadvantages described above is described in U.S. Pat. U.S. Patent No. 4,198,198. In this embodiment, the catalytic hydrogenation of the diacetone alcohol is carried out in the presence of a Raney nickel catalyst under a hydrogen pressure of 30 to 35 bar at 80 ° C. In addition to the indisputable advantages, this solution has the serious disadvantage of requiring a very high amount of catalyst, 18-20% by weight of the diacetone alcohol. A further disadvantage of this process is that 5 to 25% by weight of water is added to the diacetone alcohol, which is then removed by rectification from the reaction mixture. Despite the more moderate hydrogenation conditions, U.S. Pat. A significant amount of by-products (e.g., i-propanol and i-butylmethylcarbinol) are formed using the process of the Canadian Patent, due to the poor selectivity of Raney Nickel.

The process is accomplished under much more favorable terms by the application of Resolution 969.056. A process described in Belgian Patent No. 4,015, which achieves 100% conversion on a ruthenium catalyst supported on charcoal in the range of 30-90 ° C and a hydrogen pressure of 10-80 bar with selectivity such that the product obtained without further rectification is commercially acceptable.

The advantage of these very favorable manufacturing parameters is outweighed by the unusually high amount of ruthenium catalyst required to carry out the process (5 g ruthenium / kg product), which puts a heavy economic burden on the high price of ruthenium. A further disadvantage of ruthenium catalyst is that it must be carefully pretreated with high purity inert gas.

Based on all of these, our goal was to develop an industrial-scale, low-cost Raney-Nickel catalyst that can be used to produce the 453,324 catalyst. U.S. Pat. For reasons of economy, no. In contrast to the Belgian patent, which has a hydrogen atom at 10 bar, we have sought a type of catalyst which can reduce the diacetone alcohol to hexylene glycol at a hydrogen pressure of less than 6 bar. type autoclaves commonly used in industry max. They have a pressure of 6 bar. A suitable catalyst enables the production of hexylene glycol in a low-cost model apparatus instead of a costly slurry reactor.

In our experiments, it has been found that the use of Raney nickel catalysts (dotted) with up to 5% chromium and / or molybdenum to reduce diacetone alcohol to hexylene glycol also results in a process of 70-170 ° C at a hydrogen pressure of less than 6 bar. , preferably at 100-140 ° C, with 100% conversion. Maximum catalyst activity was observed when chromium and molybdenum were present in the catalyst in the same amount or nearly the same amount; if only one component was present, the process was much slower and did not occur at hydrogen pressures below 5 bar.

The selectivity, contrary to the Canadian patent, was greater than 98% even without the addition of water.

The following examples illustrate the process without limiting the scope of the invention to the experimental parameters set forth in the examples.

Example 1

Into a 250 cm ³ batch reactor, which was emptied at 125 ° C and fitted with an internal stirrer, was charged 50 g of diacetone alcohol and 2.5 g of Raney-Liquor catalyst, which had been previously activated and had the following composition before activation:

chromium: 1.25 wt% molybdenum: 1.25 wt% nickel: 46 wt% aluminum: 51.5 wt%

The mode of activation corresponded to the preparation of W 6 type Raney's: the activated catalyst had an average particle size of 50-100pm. Hydrogen gas was introduced into the apparatus via a control valve set at 5 bar. 8 hours after the start of stirring, the reaction was complete and the hexylene glycol yield was 99.5%.

Example 2

In all cases, the procedure of Example 1 was followed except that a Raney Nickel catalyst was used which had the following composition before activation:

chromium: 2.0% molybdenum: 0.0% nickel: 48.1% aluminum: 49.9% and the hydrogen pressure in the apparatus was adjusted to 15 bar. At these experimental parameters, the reaction was completed after 10 hours, yielding 98% hexylene glycol.

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Example 3

All were carried out as in Example 1 except that the conventional Raney nickel catalyst was used as the catalyst. There was no conversion after 8 hours.

Example 4

The reaction was carried out as described in Example 1 except that the pressure was maintained at 4 bar and a catalyst treated with 1 to 1% chromium and molybdenum was used. The reaction was complete in 9 hours with a yield of 99.2%.

Claims (1)

_5. A process for the preparation of diacetone alcohol hexylene catalytic hydrogenation at 70-170 ° C, characterized in that the hydrogenation is 4-6 bar, preferably 5 bar hydrogen pressure, on the diacetone alkohol10 to 4-6% was activated in a known manner, of a Raney nickel catalyst impregnated with 1.5 to 3% chromium and molybdenum. Without drawing Published by: National Office of Inventions, Budapest Responsible for publishing: Zoltán Himer, Head of Department N ° 5997. Printing company, Uzhhorod