NO136202B - - Google Patents

Abstract

Process for the continuous hydrogenation of oils, fats, unsaturated fatty acids and unsaturated fatty alcohols.

Description

The present invention relates to a method for the continuous hydrogenation of oils, fats, unsaturated fatty acids and saturated fatty alcohols with 10 - 30 carbon atoms in the molecule with hydrogen in a flow autoclave to form the corresponding partially or fully saturated products. In this way, the hydrogenation can be carried out selectively, the content of trans isomers varying within the limits of 3 to 20%, so that the products obtained have suitable rheological properties.

Vegetable oils, animal fats, fatty acids and fatty alcohols with varying degrees of saturation are themselves very important raw materials for foodstuffs and the chemical industry. For their application, the degree of saturation plays a very important role. Natural solid fats do not always meet the requirements set for the application. The purpose of the hydrogenation of vegetable and animal oils and fats is to produce a solid fat or a fat of a more viscous consistency than the original liquid oils with the eventual removal of some materials that cannot be removed in any other way. This enables the use of fat even in cases where the unrefined fat cannot be used. The same also applies to other materials of mono or polyene character.

The hydrogenation of vegetable oils, animal fats and some other materials based on unsaturated fatty acids, alcohols, etc., to the corresponding more saturated compounds has, since their discovery and their industrial application, undergone several developments. The investigations and technological implementations mainly use the fundamental scheme of batch hydrogenation, whereby a solid powder catalyst (most often nickel as pure metal or on a carrier) and finely dispersed hydrogen are suspended in the mass of the liquid phase (vegetable oil, fat, unsaturated fatty acids, etc.) introduced in this suspension. Another technological method in the hydrogenation of oils and fats consists in the circulation of the catalyst suspended in a hydrogenated component through a reactor with a hydrogen atmosphere. These technological methods are also retained in the hydrogenation of unsaturated compounds in the presence of a solvent. From the above scheme as proposed by Norman in 1902, there is no deviation in the technological principle in any of the continuous methods. The technological resolution of this hydrogenation can be realized in a reactor or in a cascade of reactors. New is e.g. The Lurgi, Pintsch-Bamag and Buss systems emerged. The hydrogenation of free unsaturated fatty acids broke through considerably later compared to oils. The difficulties consisted in the higher requirements for the activity and duration of the catalyst. All the methods for hydrogenating oils and fats in suspension with a powder used up to now on an industrial scale suffer from some shortcomings. These primarily include the difficult process of separating the catalyst when the hydrogenation is complete. This operation also complicates the above continuous methods.

In any case, it is a batch method (usually filtration in a filter press) that requires manual work. Another disadvantage consists in relatively high temperatures (technologically feasible hydrogenations require l8o C and more) to which organic materials are subjected for relatively long times (3-8 hours). The reaction time is affected by the relatively low concentration of catalyst and hydrogen in the reaction mixture. During the hydrogenation with a suspended powder catalyst at the usual technological temperatures, a product is always obtained with a high content of trans isomers of fatty acids (20 - 40%). Only some forms of the continuous hydrogenation of oils and fats deviate more or less from the above technological scheme and provide a different solution to the process. E. R. Bolton & E. J. Lush worked out in 1921 - 1927 the continuous hydrogenation of oils and fats on a fixed bed catalyst to avoid the difficult work with powder catalyst. Metallic nickel in the form of string and shavings with a chemically activated surface (oxidation with HNO^, anodic oxidation with subsequent reduction of the nickel oxide with hydrogen) was used as catalyst. However, this interesting process has not been realized technologically due to a number of difficulties. Metals and their alloys in the form of shavings, strips or tiles which are activated in any way are used in the catalysis reaction only in their relatively thin surface layer. There is no difference between the activation of metallic nickel by the method according to Bolton & Lush and the catalysts obtained by leaching Raney alloys. This active surface layer is considerably stressed (by the hydrogenations in the liquid phase) and must be renewed after a relatively short time. During the periodic regeneration of the catalyst, the equipment is out of operation for a relatively long time. The work with concentrated alkali liquor in the leaching of Raney alloys or work with nitric acid or dissolution of electrolytes in Bolton & Lush activation also produces catalytic hydrogenation of unsaturated hydroxy acids and their esters, and the obtained hydrogenated products did not find a practical application, due to relatively high working pressure and the low volume rate of hydrogenated materials..

For a number of products in the food industry, e.g. production of margarine, lard and edible fat, the crude fats used must have some necessary properties. As in most cases these products are hardened fats or mixtures of hardened fats and vegetable and animal fats and vegetable oils, the purpose is to obtaining mixtures with certain rheological properties and/quantitative parameters. Very good results were obtained with selectively hardened greases, i.e. the fats that contain the required amount of mono- or di-unsaturated fatty acids.

The problems with the selective curing of oils and fats by the classical methods, i.e. by the heterogeneous catalytic reaction with metallic catalyst dispersed in oil and with circulation or a stationary hydrogen atmosphere, has been treated by a number of authors. Only fundamental properties for the given type of method have been achieved, and it is thus difficult to determine the nature of the reactions unequivocally. The higher selectivity of the process can usually be achieved with a catalyst with low activity, low hydrogen concentration and the higher working temperature.

Also of interest are the methods that give the process higher selectivity with metals other than nickel, or by adding these metals together with some organic materials of a non-fatty nature. When using heterogeneous catalyst copper on a support at a concentration of 0.01 - 2% copper, a pressure of 1 -

100 atm and temperature of 150 - 220°C, a high degree of selectivity was obtained. A similar effect can be achieved by adding some materials with hydroxyl groups (up to 5%), or by forming this group during the process. These materials include e.g. mannitol, sorbitol, butanol, octanol, etc. Classic nickel catalyst on a carrier in normal quantities is used.

The method of continuous hydrogenation of oils, fats, unsaturated fatty acids and unsaturated fatty alcohols according to the present invention makes it possible to obtain products with the desired degree of saturation and possibly with suitable rheological properties. The hydrogenation is carried out continuously as follows: In a flow reactor with a solid layer of nickel catalyst on a very mechanically resistant support, a hydrogenated material preheated to the desired temperature is introduced from the top. The catalyst in the form of pellets or in some other form contains 5-85% by mass, preferably 20-60% by mass of nickel on a support, the ratio of the molar amount of reduced metallic nickel to the amount of nickel in oxide form being 10:0 .5 to 1.5:10, and at a pressure of 0.2 - 45 atm,

a temperature of 60 - 26o°C and a volume rate of supplied liquid of 0.2 - 10 liters per liter of catalyst per hour. In addition, a catalyst can be modified inside the reactor or outside the reactor with sulfur-containing or phosphorus-containing materials to

get 0.02 - 5 mass% sulphur, 0.01 - 5 mass% phosphorus individually or in a mixture in relation to the amount of nickel. The product leaving the catalyst layer is clear and does not need to be filtered.

Example

In all the cases indicated, the hydrogenated material was fed together with hydrogen in the upper part of hydrogenation reactors filled with a catalyst. A nickel catalyst was prepared according to Czechoslovak patents 111,791 and 130,468, reduced to the desired extent followed by passivation. The reactor was filled with passivated catalyst, the activation being carried out in the reactor over a period of 3 hours with hydrogen at a temperature of 160°C and a volume rate of the hydrogen of 400 liters per minute. liters of catalyst and hour. The modification of the catalyst with sulfur or phosphorus was carried out directly in the reactor with sulfur- or phosphorus-containing compounds. A hydrogenated liquid material flows down over the pellets of catalyst into the lower part of the reactor connected to a separator, where the liquid is separated from the hydrogen. The amount of hydrogen withdrawn was 5 N liters per 1 liter hydrogenated raw material. The dosing of raw material was achieved by the variable pump capacity of the feed pump. The hydrogen pressure in the reactor was maintained by a reducing valve. The temperatures of the preheater and the reactor were regulated by the amount of power introduced into the heating equipment.

Attempt 1

Hydrogenation of deacidified and bleached sunflower oil.

Iodine number (according to Hanus) 127.4.

Acid number 0.43-

Content of phospholipids 0.09% as lecithin.

A nickel catalyst on a support, nickel content of the catalyst 51%, the amount of reduced metallic nickel 6l%.

Attempt 2

Hydrogenation of olein (mixture of fatty acids) .

iodine number (according to Hanus) 49.1.

Acid number 202.2.

A nickel catalyst on a support, nickel content of the catalyst 51%, the amount of reduced metallic nickel 6l%.

Attempt 3

Hydrogenation of oleyl alcohol (octadec-9-en-l-ol).

Iodine number (according to Hanus) 90.5-

Hydroxyl number 2o4.0.

A nickel catalyst on a support, nickel content of the catalyst 51%, the amount of reduced metallic nickel 61%.

Attempt 4

Hydrogenation of sunflower oil.

Iodine number (according to Hanus) 132.4.

Acid number 0.4l-

Catalyst nickel on support (diatomite), nickel content 45.2%, amount of reduced metallic nickel 24%.

Attempt 5

Hydrogenation of sunflower oil.

Iodine number (according to Hanus) 127.4.

Acid number 0.43.

Catalyst nickel on carrier (diatomite), nickel content 52%, amount of reduced metallic nickel 94%-

Content of bound sulfur in relation to nickel 4.1%-

Claims (1)

Process for continuous hydrogenation of oils and fats containing in glyceride form besides monounsaturated also polyunsaturated fatty acids, of unsaturated fatty acids and unsaturated fatty alcohols with 10 - 30 carbon atoms in the molecule to the corresponding partially or completely saturated compounds with hydrogen in a flow reactor, where preheated, unsaturated , liquid materials are fed from the top onto a solid layer of catalyst on a carrier, where the hydrogenation takes place in the film of liquid that wets the catalyst, characterized in that a catalyst containing 5-85% by mass, preferably 20-60% by mass, is used. nickel on a support, the ratio of the molar amount of reduced metallic nickel to the amount of nickel in oxide form being 10:0.5 to 1.5:10, and at a pressure of 0.2 - 45 atm, a temperature of 60 - 260°C and a volume rate of supplied liquid of 0.2 - 10 liters per lite.r catalyst per hour.