CS258110B2 - Method of adsorbent production for principal air components separation - Google Patents

Description

The invention relates to a process for the production of an adsorbent for separating the main air components; the adsorbent is produced from rhiolite turf containing mordenite, and the treatment according to the invention is intended to achieve more intense nitrogen adsorption than oxygen in this type of rock. The treated rock is then a suitable charge of adsorption units for the production of oxygen and / or nitrogen or gases enriched with oxygen and / or nitrogen from the air.

To date, mainly zeolites have been used for these purposes, which have long been used for the selective separation of different sized molecules, utilizing the ability of zeolites to act as molecular sieves.

> For the separation of gaseous components with small molecular size differences, for example for the separation of oxygen and nitrogen, an adsorbent must be used which adsorbs more of one of these components and the other components are retained less. For this purpose, some synthetic zeolites or rocks containing natural zeolites may be provided, which are then suitable for the selective adsorption of nitrogen from the air and may be the basis for developing an effective adsorption technology for separating the air components.

Known methods for separating components of gaseous mixtures by means of gas adsorption are generally based on a change in the adsorption capacity of the adsorbent as a function of changes in temperature or pressure. In separating the air components, the desired effect is achieved mainly by changing the air pressure and short adsorption and desorption times. The patents describing this method under varying pressure and apparatus for carrying out these processes also disclose some adsorbents useful for air separation.

For example, DE-PS No. 1,265,724 discloses A-zeolite acting as a synthetic molecular sieve as a suitable adsorbent for selectively separating nitrogen from air. Also the solution according to DE-PS No. 2 312 71'0 uses zeolites with a certain crystalline structure, for example Ca-A ^, zeolite as adsorbent.

These solutions list commonly used synthetic zeolites as useful adsorbents and do not deal with increasing the selectivity of adsorbents to make the process more efficient and effective. Other solutions aim at replacing relatively expensive synthetic zeolites with cheaper adsorbents, for example, by some types of ground and heat treated rocks.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for the production of such an adsorbent whose selective adsorption ability to nitrogen is substantially improved compared to known adsorbents used for air decomposition and which can be produced in a simple and economical manner from mineral raw materials.

This object is solved by a method for producing an adsorbent for separating the main constituents of air from the rock of the invention, whose principle consists in that the rock containing an amount ^{of 4} 25 to 100 percent of the mordenite and, optionally, other zeolites and / or crystalline or amorphous mineral components having a pore diameter of from 7.5 nm to 7550 nm and a pore volume of 0.38 cm / g, are treated with a solution or melt containing metal ions, in particular sodium ions, at a temperature of 290 to 400 K and the ion exchange substance thus obtained is activated at 600 to 900 K by vacuuming or supplying the activation gas.

In a particular preferred embodiment of the process according to the invention, the rock containing at least partially mordenite is ground to particles before or after the ion exchange, and the substance thus obtained is then granulated with optional addition of a binder.

The adsorbent obtained by the process according to the invention has the advantage, in comparison with the previously known adsorbents, that the adsorption proceeds much faster as well as the subsequent desorption due to the specific structure of the adsorbent according to the invention. The preparation of the adsorbent by the process according to the invention is very simple and the adsorbent is produced from cheap basic raw materials. The adsorbent thus produced is particularly suitable for separating the constituent air components from one another.

By the method according to the invention it is possible, for example, to treat rocks from the Tokaj Mountains, from which, for example, the selected sample had the following chemical composition:

Table I

Chemical composition of rock sample

Component Quantity in% S1O2 69.10 A12O3 14.75 Fe2O3 1.20 Na2O 1.50 K2O 1.65 MgO 0.52 CaO 2.02 MnO 0.32 T1O2 0.08 loss on ignition 8.80

X-ray diffraction values as they pass through rock are given in Table II. The X-ray refractogram shows that the rock contains mordenite, which is a prerequisite for the production of the adsorbent according to the method of the invention, and which is to be contained in the rock at least 25% by weight.

Table II

Basic X-ray diffraction lines of rock sample d / А / I / I _o ⁺

13.5520

9.0560

6.5750

6.0510

5.7920

4.5140

4,25—

3.9860

3,77—

3.6410

3,47100

3.3960

3.35—

3.2280

3,192,8930 ⁺ relative line intensities characteristic of mordenite

The chemical composition of the rock and the X-ray diffraction patterns of the rocks usable for carrying out the process according to the invention may deviate more or less from the values given in Tables I and II.

The rocks which are suitable for the production of the adsorbent by the process according to the invention may contain, in an amount of 0.5 to 2.4 milliequivalents per gram, those cations which can be replaced by other cations by treating the rock with a solution or melt containing metal ions or NHd ions.

When treating the rock in the form of a pulp with a selected grain size with a solution containing sodium ions or a melt with the same ion content, under certain conditions an increase of the sodium ion content can be achieved compared to the content of other alkaline ions and alkaline earth ions. In addition to sodium, potassium, calcium, magnesium, iron, barium, strontium or other metallic elements can also be used for ion exchange. The pretreated element must be activated before being used as an adsorbent.

During activation, the rock and thus also mordenite lose water, so that the pores are better prepared for adhesion. Dehydration of the rock can be achieved by heating it to a temperature of at least 600 K, the effect being enhanced by simultaneously reducing the ambient pressure or blowing it with a stream of inert gas. Activation should not be carried out at temperatures higher than 900 K, because at higher temperatures the structure of the morde.nitus may be compromised and thus its adsorptive capacity may be significantly reduced.

EXAMPLE 1 g of a 1.0 to 1.6 mm grain size rhiolite turf granule containing 50% by weight of mordenite and originating in the Tokaj Mountains was heated in 60 ml of 1N NaCl solution under reflux for 4 hours, whereupon solution was replaced by fresh saline, which was heated for an additional 4 hours. The solution was decanted and the sample was washed with distilled water.

The treated rock pulp was then subjected to a vacuum of 10 ¹ Pa at a temperature of 600 K for 8 hours. The adsorption capacity of the thus prepared adsorbent at 293 K and the pressure of 10 ⁵ Pa for oxygen was 0.16 mmol / g nitrogen and 0.76 mmol / g.

Example 2

To 10 g of a 250-400 μΐη rhiolite grain granule fraction containing 50% mordenite by weight, 60 ml of a concentrated NaCl solution was added and the solution was refluxed for 4 hours. The solution was then decanted, an equal amount of fresh solution was added to the rock, and the mixture was then heated for 4 hours. The sample was decanted, dried, and used as a gas chromatography column, where it was gradually heated to 600 K and held at this temperature for 4 hours while nitrogen was passed through the column.

The adsorbent-activated column was loaded into a gas chromatograph, at which temperature stabilized at 293K, and a 1 ml sample of air coming in helium as a carrier gas was fed to the chromatograph at a rate of 20 ml / min. For the air sample, a separation value of 35 s per minute was achieved, which is significantly more than the ion exchange of the adsorbents used hitherto.

Example 3

A gas mixture containing 95 percent oxygen was prepared at room temperature using a granular fraction of ion exchange exchanged rhiolite activated at a temperature of 650 K and a pressure of 100 kPa in dry air. This gaseous mixture was prepared by means of a device comprising a cylindrical column of 2 m height and an inner diameter of a column of 3 cm in which a 3 kg load of adsorbent was loaded. The apparatus operates in a continuous mode of operation in which the pressure inside the column is first reduced to 1 kPa, after which the column is filled with pre-dried air to a pressure of 400 kPa, and then oxygen-enriched gas is taken up from 258110 until the pressure drops to 350 kPa.

The process according to the invention makes it possible to prepare an adsonbent which can then be used for the production of oxygen or for the enrichment of the air with oxygen, thus helping to solve various industrial, agricultural and environmental tasks.

Claims (2)

SUBJECT Process for the production of an adsorbent for separating the main constituents of air obtained by treating the starting rock, characterized in that a starting rock containing at least 25% mordenite, clinoptilolite, zeolites and / or crystalline or amorphous mineral components and having a pore diameter of 7 , 5 nm to 7 500 nm and a pore volume of 0.38 cm ³ per gram, is treated with a solution, in particular aqueous or melt, containing metallic, in particular sodium, potassium, calcium, magnesium, iron, barium or strontium ions at 290 up to 400 K, whereupon the ion-exchanged substance is activated at 600 to 900 K by vacuum or gas purging. . 2. The method according to claim 1, characterized in that, prior to the ion exchange, the starting rock is comminuted to particles of different grain sizes, and the pulp is then granulated, in particular with a binder additive.