SU1174376A1 - Method of producing silica gel for chromatography - Google Patents

Abstract

1. METHOD FOR PREPARING SILICAHEL FOR CHROMATOGRAPHY, including gelation of hydrosol {silica, freeze-granulation, filtration, drying of xerogel followed by calcining, in order to increase separation capacity in liquid chromatography, hydrosol used hydrosol used hydrosol 8-12 nm, molar ratio of srs / mago 310: 1 and silica concentration 7-25 wt.%, And gelling is carried out by adding nitric acid to pH 5.8-6.2. Section 2. A method according to claim 1, characterized in that the granulation is carried out by freezing at -

Description

The invention relates to the synthesis of inorganic sorbents, in particular silica gels, with a narrow pore size distribution and can be used in the manufacture of chromatographic materials and carriers for catalysts. The purpose of the invention is to increase the separating ability of silica gel as a sorbent in liquid chromatography. Example 1, 16 l of silicasol obtained by ion-exchange conversion of a solution of sodium silicate, selected in the pH range of 2.4-2.8 and having a Si02 concentration of 3.5 wt.% At a rate of 2 l / h is added to 8 l of 0.0075 n . caustic soda solution (pH 11.8). The process is carried out in a vacuum cooler with simultaneous distillation of water with a shortening of 2, l / h at 70 ° C. The resulting silica sol has a final pH of 6.7, the average particle diameter B nm, molar ratio SiOj / Na O 310: 1, concentration. by SiO 7 wt.%. I Add nitric acid to pH 5.8 with vigorous stirring. The resulting hydrogal is subjected to aging at room temperature for 48 h, then frozen at -20 ° C. After 24 h of the hydrogel, it is thawed on a water bath (80 ° C) and the separated xerogel is filtered off, dried from at 1 ° C, and calcined at 400 ° C for 4 hours. The product has the following characteristics: Specific 380 surface Total 0.57 pore volume Average pore diameter of particle size0, 16-0.5 mm. The composition of 52 liters of silicazo. An example of 1 liter (pH 2.4-2.8) containing 3.8% by weight of SiOj is added at a rate of 2 l / h, 8 l of 0.0125 n. sodium hydroxide solution (pH 12) in order to avoid lowering the pH value to the area of minimum stability, after the first 8 liters are supplied, every 20 liters, 62 ml of 20 ml of 1N are added to the silicas being boosted. caustic soda solution. The distillation of water is carried out at a rate of 2 liters / hour. The resulting sol has an average particle diameter of 10 nm, a SiOj concentration of 25 wt.%, A molar SiOi / NajbO ratio of 310: 1. Nitric acid is added to silicasol to pH 6.1, and the resulting hydrogel after aging at room temperature for 24 hours is frozen for 24 hours. After thawing and filtration, the xerogel is dried at 200 ° C and calcined at 450 ° C for 3 h. Get silica gel with the following properties: Specific 220 surface Total 0.55 pore volume Average 10 nm pore diameter Particle size composition 0.16-0.25 mm Example 3. 56 l silica gel (pH 2.4-2.8) containing 3.7 wt.% SiO-j, at a rate of 2 l / h, is added to 8 l of 0.035 n. caustic soda solution (pH 12.5). The rate of distillation of water 2 l / h at 75 ° C. Formed with 8 l of silicasol with a content of 510 g of 25 wt.%, An average particle diameter of 12 nm, and a molar SiOj / Na O ratio of 310: 1. Gelation is carried out by adding nitric acid to pH 6.2, aging for 36 hours at room temperature, freezing is performed at -20 ° C for 24 hours. After thawing and separation by filtration, the xerogel is dried at 180 ° C and calcined at 400 ° C for 3 hours. The product has the following characteristics: Specific surface 170 Total pore volume 0.51 Average pore diameter Particle size 0.16-0.5 mm composition The resulting products are ground in a jet mill to an hour size of less than 25 microns, then sedimentation in water and acetone oh medium in cases Fractions 5 ± 1 10 + + 2.20 In Table 3 microns pr1% edeny of determining separation efficiency (number of theoretical plates of 1 m) and the asymmetry factor 64 when using the sorbents in HPLC. Conditions for determining: a column of 150-4 mm granulation of the sorbent 10 + 2 µm; eluent - hexane, test mixture - pentai - toluene - nitrobenzene. The parameters are calculated from the peak of nitrobenzene.

6 6

Known 1 2 3

10 12

As can be seen from the table, the separation efficiency when using sorbents obtained by the proposed method is significantly higher than

2.3 M 1.1

1.1

in a sorbent prepared in a known manner, which allows solving more complex problems of chromatographic separation without increasing the column length.

Claims (3)

1. METHOD FOR PRODUCING SILICA GEL FOR CHROMATOGRAPHY, including gelation of a silica hydrosol, freezing granulation, filtration, drying of a xerogel followed by calcination, characterized in that in order to increase the separation ability in liquid chromatography, a hydrosol with the size of silica uses 8 hydrosol with -12 nm, molar ratio Si0 ₂ / Na ₂ 0 = = 310: 1 and silica concentration 7-25 wt.%, And gelation is carried out by adding nitric acid to S pH 5.8-6.2. 2. The method according to π. 1, characterized in that the granulation by freezing is carried out at - (20) - (- 25) ° C. 3. The method of pop. 1, characterized in that the drying is carried out at 180-200 C, and calcination at 400-450 ° C. > I "