SU422718A1 - METHOD OF OBTAINING GLYCERIN AND GLYCOLES - Google Patents

Description

one

This invention relates to a process for the preparation of polyhydric alcohols, namely glycerol and glycols, which find various uses.

A known method of producing glycerol and glycols by the hydrogenolysis of sugars in the presence of a catalyst — nickel on diatomaceous earth and alkaline additives at 200 ° C and a pressure of 30-50 atm. The process is conducted under conditions of vigorous stirring with a Reynolds criterion of 60,000. The disadvantages of this method are the high consumption of compressed hydrogen (up to 10 volumes per 1 volume of an aqueous solution of sugars), as well as the complexity of the process flow. The mixture of partially reacted sugars, catalyst and excess hydrogen at a temperature of 200 ° C and pressure up to 150 atm from the cascade of reactors is sent to a high pressure separator and to drop separators. The separated gas containing unreacted hydrogen is cooled in high pressure heat exchangers and sent to the compressor. The compressed gas is again heated to 200 ° C and returned to the reactor (sparging). Part of the gas is taken out of the cycle, which allows the addition of fresh hydrogen. In case of insufficient sugar conversion, the latter, together with the catalyst, are returned from the separator to the reactor by means of hot pumps.

In order to eliminate the above disadvantages of the proposed method, the mixing is carried out with the Reynolds criterion 100000-200000.

The process is preferably carried out at a pressure of 100-150 atm with preheating of the raw slurry in the presence of hydrogen to 150 ° C under vigorous stirring conditions using the Reynolds criterion 100000-200000.

Compressed hydrogen is preferably served in the amount of 0.25-1.5 volume per 1 volume of raw slurry per hour.

The proposed method has several advantages. The internal circulation of the reactants eliminates the need for stirring by bubbling, which is the external circulation of hydrogen using the above complex

a system incorporating a circulation compressor. The supply of hydrogen to the reactor is reduced from 10 to 0.25 volumes per 1 volume of the raw slurry, i.e., 40 times. The process is carried out in an apparatus having an inline pump and a separator, which allow the gas to be removed from the reactor without entraining the raw material. This eliminates the operation to return partially reacted sugars and catalyst to the reactor. Built into the reactor

Heat exchangers exclude the possibility of overheating of the Sugars hydrogenation process, which was not achieved by previously known methods.

Example 1. As a reactor, an apparatus with a useful capacity of 650 cm is used, equipped with a diffuser and a helical stirrer, the rotation speed of which is 2800 rpm. The hermetic-driven mixing device provides the intensity of the three-phase mixing of the solution of monosaccharides, the catalyst is nickel (50%) on kieselguhr and hydrogen corresponding to a Reiolds number of more than 100,000. The reactor is heated with an electric furnace that provides 235 ° C in it.

At the pressure of 100 atm, a dosing pump containing 10% glucose solution with the addition of 2.5% Ca (OH) 2, 2.5% GeSC-bNgO and 8% catalyst – ikel on kieselguhr from glucose weight. Compressing hydrogen in an amount necessary for hydrogenolysis of glucose (), with a minimum excess corresponding to a modulus of 0.25 (500 at the reaction pressure or 50 hydrogen at normal pressure) is fed through the other fitting to the reactor. The amount of excess hydrogen is measured after the gas separator when it is reduced to the atmosphere; recirculation of such small amounts of hydrogen is not required.

The suspension leaving the reactor, after cooling and separation of the gas, is throttled, filtered from the catalyst and analyzed. Hydrogenate contains (in% of dry substances): higher polyols (sorbitol, xylitol, erythritol) 23, glycerin 42, ethylene glycol 15, 1,2 propylene glycol 15.

Example 2. An aqueous solution of sugars, for example, obtained from non-food raw materials (from wood waste) in a mixture with suspended catalyst and hydrogen, added in an amount of 0.25, is fed to a preheater reactor equipped with built-in heat exchangers. Raw fast

(15 min) and heat from 20 to 150 ° C, which leads to partial hydrogenolysis of glucose without first hydrogenating it into hexites and without undesirable decomposition of the raw material. 5 The resulting suspension — the foam — is sent to the reactor, which provides a stirring intensity corresponding to a Reynolds number of 100,000, at a pressure of up to 150 atm and a temperature of up to 250 ° C, where at a contact time of 30 min the conversion depth is brought to 70% and more. The resulting gases — methane, carbon monoxide, and water vapor mixed with unreacted hydrogen — are removed from the reactor using an integrated separator.

15 The resulting product is sent to the reactor cooler, where the suspension is cooled from 250 to 40 ° C by means of an integrated heat exchanger. Further processing of the products of hydrogenolysis lead in the usual way.

Subject invention

Claims (4)

1. A method of producing glycerol and glycols by the hydrogenolysis of sugars in the presence of a catalyst — nickel on diatomaceous earth, alkaline additives and a cocatalyst — metal salts, under conditions of intensive non-displacement, at elevated temperature and pressure, followed by separation of the target products by known methods, characterized in that in order to simplify the nrocess technology, mixing is carried out with a Reynolds criterion of 100000-200000. 2. The method of Claim 1, characterized in that 5 that the process is carried out at a pressure of 100-150 atm. 3. The method according to claim 1, characterized in that the raw slurry is previously agglomerated in the presence of hydrogen to 150 ° C under conditions of vigorous stirring at 0 value of the Reynolds criterion 100000-200 000. 4. A method according to claim 1, characterized in that the compressed hydrogen is supplied in an amount of 0.25-1.5 volumes per 1 volume of the raw material suspension per hour.