CS201188B1 - Method of preparation of the chromatographic bearer - Google Patents

Description

(54) A method for preparing a chromatographic support

The invention relates to the preparation of a chromatographic support particularly suitable for gas chromatography.

Kieselguhr supports for stationary phases for gas chromatography are prepared from physically and chemically purified diatomaceous earth by annealing, generally using alkaline fluxes such as sodium hydroxide, carbonate or silicate. Grinding and screening are further adjusted to a suitable grain size.

The quality of the final product is influenced by many factors. First of all, it is the quality of diatomaceous earth, expressed by the type and degree of crushing of silica diatom shells, and in particular the content of aluminous and clayey impurities, which impart to the diatomaceous earth oxides of divalent and trivalent metals such as calcium, magnesium, iron and aluminum. The physical cleaning of diatomaceous earth, which consists in washing away unsuitable particles, either too fine particles or particles with higher density, has also a significant effect. Chemical cleaning, usually consisting of acid leaching, removes minor components, mainly ferric, aluminum and calcium compounds. Furthermore, the quality of the product is influenced by the quantity and quality of the fluxes and the annealing regime. Typically, about 5% fluxes based on kieselguhr weight and annealing temperature of 1,100 to 1,300 ° C are used. A disadvantage of carriers prepared without the use of fluxes is their relatively high sorption activity and the disadvantage of the carriers prepared using alkaline fluxes is their low mechanical strength, manifested in their easy grinding and particle abrasion.

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The production costs of the chromatographic supports are relatively high, since in the case of non-standardized diatomaceous earth, it is necessary to select a suitable part in the process of its processing into a support and often to a finished product. For this reason, there is a tendency to use entirely synthetic carriers, for example based on silica or aluminum silicates, for which the quality variability factor of the natural raw materials is not active.

The above disadvantages substantially reduce the process according to the invention. It is based on the fact that a waste cratified catalyst is used as a raw material, containing from 1 to 15% by weight of carbon, generally in the form of carbonized substances, 0.1 to 10% by weight of phosphorus, usually in the form of phosphoric acid, up to 3% by weight of copper and salts thereof, such as for example, silicate, and fluxes are used with mixtures of sodium nitrate or potassium nitrate with fluorides and / or carbonates or with hydroxides of alkali metals such as sodium and potassium.

The milling of the starting waste catalyst can be carried out in a dry way, in which case if the catalyst contains more than about 10% water, its content must generally be reduced below the drying limit to avoid clogging of the grinder. The tolerance to the water content of the catalyst is determined by the type of grinding device used. In the case of wet grinding, ie in an aqueous environment, the need for drying is eliminated.

The acid leach consists in heating a suspension of the particulate material in an aqueous solution of inorganic acids such as hydrochloric acid, nitric acid or sulfuric acid at a temperature of 40 to 120 ° C for 1 to 20 hours and washing the particles with water. This operation can be carried out once or repeatedly by replacing the acid leach solution. The acid leaching may be carried out before or after the alkaline leaching, but in principle always before the combustion of the carbonized organic substances.

Alkaline leaching involves etching particles of material by stirring their suspension in an aqueous solution of inorganic bases such as sodium hydroxide or potassium hydroxide at a temperature of 15 to 100 ° C. This is followed by washing the particles with a dilute aqueous solution of sodium hydroxide, potassium hydroxide or ammonia, washing with water, neutralizing the alkali residues with a dilute aqueous solution of inorganic or organic acids, and optionally rinsing again with water. The alkaline leaching can be carried out before or after the acid leaching, its effectiveness is maintained even if applied after the combustion of carbonated organic substances, i.e. after annealing or after the carriers have been screened for the desired grain size.

The annealing time for the combustion of carbonated organic materials varies considerably, as it depends on the oxygen access to the burned substances and thus on the layer thickness of the material, its amount and the air flow. Furthermore, it depends on the time course of temperature, ie the size of the furnace, its output and heat capacity. The latter factors also apply to annealing the carrier with fluxes.

Sorting into grain fractions of the desired particle size, for example, grain sizes 0.1 to 0.125 mm, 0.125 to 0.16 mm, 0.16 to 0.20 mm, 0.20 to 0.25 mm, 0.25 to 0.25 mm 0.315 mm, 0.315 to 0.40 mm, and 0.40 to 0.63 mm can be performed using appropriate sieves, either by sieve drying on a dry route, or by sieving in a liquid medium, such as water, or

201 188 when water is sprayed. This sorting can be carried out either after the combustion of the carbonated organic substances or after the flux carrier has been ignited, or in both preparation stages.

In preparing the support from the waste catalyst, the active catalyst component or contaminants are removed by leaching and the organic matter is removed by combustion.

In the diatomaceous earth kieselguhr catalyst used for the catalytic hydration of olefins, it is phosphoric acid and its reaction products 8 with a silica backbone and copper and its compounds. The process according to the invention does not destroy the porous silica structure of the skeleton. Moreover, the chemical treatment removes harmful iron and aluminum impurities from it. Combustion removes carbonized organic substances formed as by-products of the hydration of olefins.

In the treatment of the purified material by flux annealing, sodium nitrate and potassium nitrate, which decompose at higher temperatures into nitrogen oxides and hydroxides, resp. sodium and potassium oxides. Presumably, the oxidative effects of nitrogen oxides and the action of active hydroxides or alkali oxides reduce the sorption effects of the support surface.

An advantage of the process for the preparation of the gas chromatography carrier according to the invention is the obtaining of a mechanically strong and non-absorptive inactive white color, the quality of which is the same as that of a carrier made of very pure diatomaceous earth. The carrier is suitable both for separating non-polar and intermediate polar substances, as well as for separating polar substances using non-polar stationary phases. The carrier flows well, fills the chromatography column well and does not adhere to dust particles during handling.

A further advantage of the carrier preparation process according to the invention is the low production cost since the carrier is produced from worthless waste which has hitherto been exported to landfills. The production cost is about a quarter lower than the cost of producing the same carrier from physically and chemically purified diatomaceous earth.

Example 1

Drying at 130 ° C treated a damp diatomaceous earth catalyst containing carbonized organic compounds expressed in carbon content of 5%, 4% phosphorus mainly in the form of phosphoric acid and even% copper and their compounds. Dried material containing!

1.5% of the water was milled in a perplex mill to a particle size of mainly less than 0.63 mtn.

Fine particles were removed from the milled material by flushing four times with 50 liter portions of drinking water while collecting larger particles from the supernatant to a 0.07 mm mesh. Water was aspirated from the suspension and the wet filter cake was suspended in the mixture

5.5 liters of 65% nitric acid and 17 liters of drinking water. With stirring, the suspension was heated to 98-100 ° C, held at this temperature for 6 hours and, after cooling, decanted twice with 20 liter portions of drinking water. The acid residue was eluted on the filter pad with deionized water until the pH of the filtrate reached 3 to 4. The filter cake was suspended in 25 liters of 2% sodium hydroxide solution. While stirring, the suspension was heated to 95-98 ° C, held at this temperature for 1 hour, and after partial cooling was brought to

201 188 filter sucker The filter cake was washed successively with 25 liters of 0.5% sodium hydroxide solution and dionized water until the pH of the filtrate reached 8-9, a 251 liter portion of 3% nitric acid solution and then deionized water until the pH of the filtrate reached 4-5. of water, the filter cake was dried at 115 ° C and calcined at 900 to 950 ° C for 72 hours. The white granular material was screened for narrow grain fractions in a particle size range of 0.10 to 0.63 mm. The so prepared carrier was used as a packed column for gas chromatographic separation of aliphatic and aromatic hydrocarbons, ethers, esters and ketones after wetting with stationary phases.

Example 2

Using the procedure of Example 1, 20 kg of a carrier having a grain size of 0.20-0.25 mm (which was further processed by flux anchoring, annealing and sieving) were prepared. The carrier was suspended in a flux solution prepared by dissolving 600 g of potassium nitrate and 1540 g of potassium hydroxide in 35 liters of saturated aqueous sodium fluoride solution (about 4% solution). The suspension was degassed by evacuation and the excess flux solution was filtered off to a filter cake weight of 34 kg, corresponding to a 14 kg solution retainer per 20 kg carrier. The filter cake was dried while moving in a hot air stream in a fluid-bed dryer at 80-100 ° C. The grained flux-coated material was calcined at 925 ° C for 4 hours and then separated by passing through a sieve with a mesh width of 0.40 mm. The so prepared carrier was used as a packed column for gas chromatographic separation of alcohols, aldehydes and amines after wetting the stationary phase.

Example 3

The damp diatomaceous earth catalyst containing 6% carbon, 15% phosphoric acid and 0.2% copper and their compounds was dried at 110 ° C to a moisture content of 2%. 500 g of catalyst were milled in a perplex mill to a grain size of mainly less than 0.63 mm. Six-fold decantation with tap water removed most particles smaller than 0.1 mm and the water was filtered off. The filter cake was stirred in a mixture of 450 g of 36% hydrochloric acid and 300 ml of water. The suspension was leached at 109 ° C for 1 hour. After partial cooling, 700 ml of the leaching solution was aspirated with a dip filter and replaced with 700 ml of 20% hydrochloric acid. The leaching at 109 ° C for 1 hour was repeated. The suspension was suction filtered and washed until the filtrate had a negative reaction to chloride ions. The suction filter cake was dried at 110 ° C and calcined at 500 to 600 ° C for 2 hours and at 850 to 880 ° C for 3 hours. The white granular material was screened by screening for fractions in the particle size range 0.100 to 0.315 mm.

g of a 0.16-0.20 mm grain fraction was suspended in 100 ml of 5% sodium hydroxide solution. The suspension was heated at 95-98 ° C for 1 hour, cooled, filtered and washed under suction with 250 ml of 0.1% sodium hydroxide solution, 250 ml of 3% nitric acid solution and then with water until the filtrate reached pH 5. 5. The filter cake was aspirate and dry at 110 ° C.

g of a 0.16-0.20 mm grain fraction was suspended in 130 ml of an aqueous flux solution.

containing 2.2% potassium nitrate, 4% potassium hydroxide and 4.1% sodium fluoride. The slurry was degassed by evacuation and aspirated to a filter cake weight of 73 g. The filter cake was dried with stirring and then calcined at 825 ° C for 4 hours. The product was passed through a 0.25 mm sieve.

Example 4

The same waste catalyst was treated as in Example 3 except that the flux solution contained 4% sodium nitrate and 5% potassium fluoride and the annealing temperature of the granular flux material was 775 ° C and the annealing time was 20 hours.

Example 5

The carrier of Example 1 was treated as in Example 2 except that 3 540 g of potassium carbonate was used in place of 1,540 g of potassium hydroxide in the preparation of the flux solution and the flux carrier was annealed at 950 ° C for 10 minutes. hours.

Example

By the method of Example 1, a carrier was prepared except that the grain fraction was not screened after annealing. This unsorted carrier was treated with flux annealing as described in Example 2 and screened to narrow grain fractions in a particle size range of 0.10 to 0.63 mm.

Example 7

By the method of Example 3, a carrier was prepared with the change that the solution contained 4.5% potassium nitrate and 5.5% sodium hydroxide and the annealing was carried out at 900 ° C for 8 hours.

Claims (1)

SUBJECT OF THE INVENTION A process for the preparation of a chromatographic carrier, in particular for gas chromatography, prepared by grinding, dust removal, acid and alkaline, leaching, drying, annealing in an oxygen-containing atmosphere, anchoring fluxes and re-annealing and screening for grain fractions, waste diatomaceous earth catalyst containing as major impurities 1-15% of carbon, usually in the form of carbonized materials, 0.1 to 10% by weight of phosphorus, preferably in the form of phosphoric acid, 10% ^4-3 wt. Copper and their salts, such as silicates, and mixtures of sodium nitrate or potassium nitrate with fluorides and / or carbonates or with alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are used as fluxes.