DE1272293B - Process for dewatering organic fluids - Google Patents

Description

Method for dewatering organic liquids The invention relates to a method for the dehydration of organic liquids by treatment with dehydrated, natural zeolites.

Drained, d. H. completely anhydrous organic liquids are indispensable raw materials in the chemical industry and are being wasted Syntheses used in large quantities as reagents or solvents. As a result the preparation of the catalytic petrochemical process should be the water content the fed-in raw materials or the product streams created during processing be kept below an extraordinarily low value in order to avoid the damage of the catalyst or the occurrence of corrosion phenomena or undesired ones to be able to avoid catalytic processes.

Various organic liquids were used to dehydrate numerous methods, including azeotropic distillation, the application of chemical Drying means, such as B. Alkali metals and alkaline earth metals and adsorptive drying worked out with silica gel or aluminum oxide, etc. Generally suitable the mentioned methods only for the dehydration of some organic liquids, and on the other hand, require the application of difficult and dangerous operations (such as drying polar solvents with silica gel and aluminum oxide).

Some of the chemical desiccants are also capable of certain to react with organic liquids (e.g. phosphorus pentoxide with alcohol) and therefore cannot always be used. A universally applicable and effective one However, methods of draining organic liquids could not be used until the time cannot be found yet.

The structurally bound water can be known between certain Temperature limits from the crystal lattice of some zeolites (alkali and alkaline earth metal aluminum hydrosilicates) can be removed without damaging the crystal lattice. That of its water content freed crystal lattice has extraordinary adsorption properties and adsorbs selectively in the pores created by drainage those molecules whose size or shape allows penetration into the pores. These Zeolites which can be used as selective adsorbents are referred to as molecular sieves.

The adsorption selectivity of the molecular sieves depends on the pore size addicted. Although natural zeolites with molecular sieve properties can also be found are, however, have natural zeolites as Molecular sieves not yet commercially available Found application because of these numerous difficulties. The pore size this zeolite is used to solve the most important separation problems, such as. B. selective Removal of water, hydrogen sulfide, sulfur dioxide, ammonia, ethylene, etc. not suitable and the "regulation" of the pore size was not yet possible be solved. In artificial hydrothermal conditions, however, the to produce numerous types of zeolite that do not occur in nature.

The manufacture of artificial zeolites is described, for example, in the United States patents 2882243 and 2882244. These can be based on the crystal structure of each other be distinguished; the individual types are designated A, B, C.

Below that, the pore size of the type designated with A can be adjusted or regulated that they are used on the one hand to separate n- or i-paraffins (5A) and on the other hand can be used for the drainage of liquid chains (3A, 4A). This type is already currently used for the production of pure n-paraffins and in certain cases for drying intermediate or end products of petrochemical raw materials applied. Information about these molecular sieves can be found, for example, in the German Patent specifications 1038017 and 1038016.

The application and dissemination of the synthetic molecule siebe is subject to certain limits. The large-scale implementation of the Synthesis is difficult. The thermal conductivity of the raw materials (such as sodium silicate, sodium aluminate, caustic soda and water) are viscous Gel is unfavorable. Despite the very intensive stirring, local Overheating occurs, causing the crystallization in an undesirable direction shifts. Therefore, there are many active impurities in the products. The resulting crystals are extremely small in grain size (0.5 to 5 Microns) and cannot be granulated on their own. The granulation is done by mixing of 200 / o inert binder, such as. B. achieved bentonite. The binder blocks however, the pores and the adsorptive properties of the granulated material deteriorate by lowering the rate of adsorption. Here too the grains easy to dust and disintegrate when exposed to water, with the result that the synthetic molecular sieves can only be used in fixed bed facilities and must be kept free of water or water vapor. Also the chemical resistance of most synthetic molecular sieves e is low; they already decompose easily with diluted acids and are also not resistant to concentrated alkalis.

The production and use of the molecular sieves is therefore expensive; their area of application and also their procurement are limited.

It has now been found that organic liquids by treatment with dehydrated natural zeolites can be dehydrated if you have one natural clinoptilolite used by grinding, treating with aqueous approximately 2 N potassium salt solution and removing the water while gradually heating to 4000 C has been prepared under inert gas purging.

With this molecular sieve, organic liquids can be more effective and dewatered more successfully than with the help of the previously used molecular sieve types will. The scope of application of the Klinoptil olite is also more extensive.

Clinoptilolite is a natural type of zeolite that is found in Hungary in found in large quantities of uniform quality just below the surface of the earth and is therefore easily accessible.

Occurrences of this mineral have also been found elsewhere (see in this regard F. A. Mumpton, "The American-Mineralogist," 45, March-April, 1960, pp. 351-369).

It has been found that an organic liquid with extraordinary low water content continuously through the use of natural zeolites is obtained when the natural clinoptilolite is ground, the ground product with Treated about 2r potassium salt solution, then washed salt-free, after washing in a column is filled, so that in the column the ratio of filling weight (in kilograms) to space volume (in liters) by 1: 0.5 to 1.0, preferably by 1: 0.6 to 0.8, then the adsorbent filled into the column heated stepwise up to 4000 C with inert gas flushing and at this temperature is held until the water content of the escaping inert gas to a practically non-determinable amount decreased, whereby, calculated. per 1 kg adsorbent, 20th up to 30 liters of inert gas per hour are passed through, then the drainage of the Organic liquid to be dewatered with the adsorption agent prepared in this way is carried out in which - depending on their water content - this the column so is supplied that the ratio of the filling weight (kilograms) and the Feed rate (liters per hour) varies in the range 1: 0.3 to 15. To When the adsorbent is exhausted, it is regenerated in the above manner by heating. It can be achieved that the water content of the organic liquid is lower than 2 ppm, i.e. H. becomes less than 0.0002%.

On the basis of the tests it was found that the invention clinoptilolite manufactured adsorbents treated the dehydration of various organic liquids continuously in a simple facility. After exhaustion of the adsorbent, the selective water binding capacity can be restored by heating in a stream of inert gas to 4000 C, so that a single adsorbent charge applied in several consecutive periods can be. The molecular sieve produced according to the invention is mainly used for Dehydration of dichloromethane and other organic liquids containing halogens, also of ethanol, isopropanol, generally alcohols, ethers, acetone, aliphatic or aromatic ethers, esters, ketones, aliphatic or aromatic hydrocarbons, including benzene, toluene, n-heptane, gasoline, cyclohexane, also tetrahydrofuran, pyridine, Butyl malonic ester or diethyl carbonate are suitable, but can also be used for dehydration of organic acids, e.g. B. acetic acid can be used.

The method according to the invention is explained in more detail using the examples: Example 1 The natural clinoptilolite (stone pit Rátka) becomes a grain size milled by 1 mm. The ground product is mixed with 1 to 2 times the amount of 2N potassium chloride solution taken up, left to stand for 1 day and then the adsorbent with distilled Washed water free of salt. The ground product pretreated in this way is placed in a column filled, heated to 4000 C for 2 hours and the emerging from the adsorbent Water vapor flushed out with a moderate stream of nitrogen (20 to 30 liters per Hour per kilogram of adsorbent). After switching off the heating device, the nitrogen flow is turned off and the activated material cooled down The weight of the 120 cm long Column-filled adsorbents after activation is 179.5 g, the space volume at 135 ml.

Then at 100ml / h. Feed speed with ethanol a water content of 0.5 percent by weight added to the column and the water content of the product flowing out of the column is determined physically and chemically. The water content of the product obtained as a function of the amount added is shown in F i g. 1 cited so-called »exhaustion curve«. The abscissa values of Fig. 1 gives the added raw material quantity in milliliters, the ordinate values the water content of the product in ppm.

From Fig. 1 it can be seen that the water content of the product is initially drops sharply, but the water content obtained is only to be regarded as apparent, because initially the product depends on the water content of the template or the analysis device is contaminated. After a while, equilibrium occurs, with the The water content of the product obtained is less than 0.00020 / 0.

In the curve, this section corresponds to the dashed line. After adding 2500 ml of the raw material to be dewatered, the water content increases of the product removed from the column quickly, as a sign of exhaustion of the Column.

The feed is then switched off, the liquid in the column drained and after passing a stream of nitrogen with the regeneration of the Adsorbents started. With regard to the activity of the adsorbent was even after repeated regeneration no reduction observed.

Example 2 The clinoptilolite ground product pretreated as in Example 1 is filled into a 70 cm long column and flushed at 4000 C with inert gas. That Weight of the column filling is 67 g, the space volume 55 ml The dehydrating solvent in this case is toluene at 0.042 percent by weight Water. The toluene is the column with 500 ml / h. Speed supplied.

Part of the exhaustion curve recorded is shown in FIG. The in F i g. 2 are associated with those of F i g. 1 identical. Since toluene is less hygroscopic, this curve lacks the one that would otherwise drop off at the beginning Part of the curve. The water content of the product obtained or of the toluene was with determined to an accuracy of 0.0004 percent by weight; the one drawn in dashed lines Section therefore means a water content below 0.0004 percent by weight. Because of this figure clearly shows that the drainage carried out according to the invention is particularly effective with non-polar solvents.

Example 3 (comparative tests) To demonstrate technical progress of the method according to the invention is in Figure 3 the performance of the invention Adsorbent compared with various commercially available molecular sieves, including with that of the Linde 4 A type (product from Linde Air Prod. Co.). For the time being Mostly the molecular sieve type 4A for the dewatering of various organic Liquids applied.

Pre-treated clinoptilolite milled product was placed in equal columns of 70 cm in length (Grain size 1 mm), rod-shaped extruded Linde 4A molecular sieve (diameter 3.1 mm), also Neviki 40Kx, as well as spherical nalsite (with 1.5 to 3 mm diameter), filled.

Neviki 40Kx, with a pore diameter of 4A, is called "Molfilit 40Kx" manufactured and sold by the "Budapest Chemical Works".

Information about »Nalsit 4«, soft from »Vurup« (Research Institute for petroleum and hydrocarbon gases) can be found in »vacuum technology«, 14, 108 (1965).

The molecular sieves were previously rinsed in the same way activated with nitrogen or by heating to 4000 C. The exhaustion curves the various adsorbents were made by dehydrating ethanol with a water content determined by 0.5 percent by weight. In Fig. 3 denotes curve 1 with clinoptilolite, Curve 2 that with nalsite, curve 3 that with Linde 4A, curve 4 that with Neviki 40Kx molecular sieves obtained exhaustion values.

The water content of the obtained product was determined with an accuracy controlled by 0.01 weight percent and the even lower water content with a dashed line Line. The remaining characters of the fig. 3 remain unchanged.

From Figure 3 it can be seen that for a given column filled with clinoptilolite, approx. 900 ml, with Linde 4A or with nalsite only 250, with Neviki 40Kx even less dehydrated product can be obtained. These significant Differences prove the advantages of the method according to the invention over others, processes using commercially available synthetic molecular sieves.

Claims (1)

Claim: Process for the dewatering of organic liquids by treatment with dehydrated natural zeolites, daclurch marked e i c It does not mean that a natural clinoptilolite is used, which is obtained by grinding, treating with aqueous about 2 N potassium salt solution and removing the water under gradual Heating to 4000 C with inert gas flushing has been prepared.