The way to determine the adsorption capacity of solid bodies

 

(57) Abstract:

Usage: the invention relates to the field of physico-chemical applications gaschromatographie, in particular, to methods of determining the adsorption capacity of solids used in the calculation of the structural parameters of the surface.

The method improves the accuracy and sensitivity of measurements, extends the operating range of concentrations, reduces the effect of "dead volume". The inventive process is carried out in vacuum, and the flow of vapor of the adsorbate is divided into the output column in front of the detector through the bypass line. After continuous transmission of the adsorbate through a column of adsorbent get frontal chromatogram and calculate the amount of adsorption on the area enclosed between the concentration fronts of the adsorbate and neadsorbirutmsa gas. 1 Il.

The invention relates to the field of physico-chemical applications gaschromatographie, in particular, to methods of determining the adsorption capacity of the solid materials used in the computation of the structural parameters of the surface of solid materials, as well as in the ceramics industry in defining the parameters of porous structure of raw mater is th desorption, which provides metered inlet adsorbate in the flow of carrier gas passing through the column with a test substance and determining the amount of adsorption on the amount of adsorbate that is allocated from the surface of the adsorbent by heating [1]

The disadvantages of this method are the low accuracy and sensitivity, which is caused by the presence of pressure surges that occur when thermal desorption and causing spurious signals.

Closest to the claimed method gas chromatographic determination of the values of adsorption, which in turn build adsorption isotherms (method Shay) adopted for the prototype [2]

The way the prototype consists of continuous transmission of the adsorbate in the mixture with the carrier gas through the column with a test substance and determining the amount of adsorption on the area enclosed between the concentration fronts of the adsorbate and neadsorbirutmsa gas. The amount of adsorption corresponding to the partial pressure of the adsorbate, build isotherms, which are calculated structural parameters of the surface of solids: specific surface area, sorption volume, the effective radius of the pore.

The disadvantages of prototypicality (0-10 vol.), due to the limited working range of universal detector gases in the heat - katharometer.

2. The impossibility of exact determination of surface parameters for pairs of volatile liquids (water, organic solvents), as this significantly increases the effect of the dead volume and diffusion erosion fronts gas and adsorbate.

The purpose of the present invention increases the accuracy and sensitivity of measurements, extending the operating range of adsorbate concentrations, reducing the influence of the dead volume.

The above objective is achieved by the fact that the process is carried out in vacuum with the division of the flow of vapor adsorbent before the detector through the loop line.

The described method also includes continuous transmission of the adsorbate through a column of adsorbent, getting the front of the chromatograms and determination of the adsorption area enclosed between the concentration fronts.

The implementation process in the vacuum provides an increase in the length of free path of the molecules of the adsorbate, reduces the retention time on the walls of the connecting lines and working vessels, which significantly reduces the influence of the "dead" volume, as is the acidity of the adsorbate in the functional volume of up to about 50. makes available for research the entire range of concentrations used (range katharometer lies in the region from 1 to about 50.).

When conducting a search not found technical solutions that in the determination of adsorption capacity of solids would pass adsorbate vapor through a column of adsorbent in a vacuum with the division of the flow front of the detector through the loop line. Therefore, the claimed technical solution meets the criteria of the invention of "novelty". A comparison of the claimed method with others in this field of technology has allowed us to identify the characteristics that distinguish the claimed solution to the prototype, which gives the right to conclude that the criterion of "substantial differences".

The drawing shows the setup diagram for determination of adsorption capacity solid phone

The installation includes a vacuum pump 1, a buffer tank 2 and 4, the shut-off valve 3, manovacuummeter 5, the leak 6, the vacuum valve 7, chromatographic column 8, valve 9, the valve-leak 10, a container of liquid adsorbate 11, thermostat 12, katharometer 13, the loop line 14 (for securing the separation of the flow at two in the ratio 1:1), bypass line 15, sinks 16 and 17, porogens> The sample silica gel SSC in the form of a hinge 0.05 g at t 20oC is placed in column 8, the adsorbate H2O in the container 11 and the whole setup vacuum to a residual pressure of 0.1 to 100 PA.

Set the starting pressure of water vapor at 200 PA with a crane-leak 10 and the bypass line 15. Get frontal chromatogram for this value of vapour pressure of the adsorbate (Fig. 2). Then repeat this operation for the intermediate values of pressure up to the maximum increments of 200 PA.

Using frontal chromatogram for each value of the vapour pressure of the adsorbate, build isotherm of adsorbate on which the BET method (brunauer, Emmett and teller) determine the basic parameters of the porous structure of the adsorbent: the specific surface Sbeats, sorption volume Vseffective radius is then reff.

In example 1, we obtained the following values:

Sbeats220 m2/g; Vs1,02 cm3/g;

Example 2.

Perform the same actions in the same sequence as in example 1, but as the sample is taken activated carbon SKT weight of 0.03 g at t -196oSince, when using as the adsorbent N2.

The values of the floor is given the same actions in the same sequence, as in example 1, but as a sample taken calcined kaolin weight of 0.3 g at t 1380oC; the adsorbate N2.

The values of the obtained parameters:

Sbeats0.08 m2/g; Vs0,03 cm3/g;

Use this method to determine the adsorption capacity of solids gives the possibility to extend the working range of vapor concentrations of adsorbate and accurate calculation of the parameters of porous structure of materials with low porosity and low specific surface area (up to 0.001 m2/g) with a relative error no more than 1%

The way to determine the adsorption capacity of solids, including continuous transmission of the adsorbate through a column of adsorbent, the detection of differential thermal detector, obtaining frontal chromatogram and calculate the magnitude of adsorption on the area enclosed between the concentration fronts of the adsorbent and neadsorbirutmsa gas, characterized in that, in order to increase the accuracy and sensitivity of measurements, extend the operating range of concentrations and reduce the effect of dead volume, the transmittance of the adsorbate through the column with the adsorbent is carried out in vacuum with the division of the flow of steam

 

Same patents:

The invention relates to chromatography and can be used to identify individual compounds or individual components of complex mixtures in various industries: chemical, oil, gas, petrochemical, oil refining, metallurgy, medicine, biology, ecology, etc

FIELD: chemical engineering; medical engineering.

SUBSTANCE: method involves plotting two chromatograms one of which is based on radioactivity (No 1) and the other one on ultraviolet absorption (No 2) or on radioactivity (No 1) and on fluorescence (No 2) and chromatogram specific relative to ultraviolet absorption (No 3) or relative to fluorescence (No 3). Material quality is estimated to be the more high the more close studied labeled compound peak shape is to trapezoid shape on the third chromatogram.

EFFECT: high accuracy of the method.

8 dwg

FIELD: analytical chemistry, ecology, in particular controlling of environmental air.

SUBSTANCE: claimed method includes aspiration if air sample through chemosorbtive medium, elution of formed dimethylamine salt, eluate closure with alkali, and gas chromatography analysis of gas phase with flame-ionization detection. Dimethylamine salt elution from adsorbent is carried out with 1 cm3 of distillated water; closured with alkali eluate is held in thermostat for 5 min; and as filling in separating chromatography column chromosorb 103, containing 5 % of PEG-20000 and treated with 20 % hexamethyldisilazane solution is used.

EFFECT: method for dimethylamine detection with improved sensibility and accuracy.

FIELD: chemical industry.

SUBSTANCE: during process of taking sample from technological pipe-line, absorption of water vapors and nitrogen oxides (II) and (IV) are conducted simultaneously. For the purpose the chemical agents are used which don't absorb nitrogen oxide and don't react with it. Chromatographic measurement of volume fraction of nitrogen oxide (I) is carried out by means of industrial chromatograph having heat-conductance detector by using column of thickness of 5 m and diameter of 3 mm. The column is filled with polysorbent; temperature of column's thermostat is 20-30 C and temperature of evaporator is 100C. Hydrogen is used as a gas-carrier. Concentrations of nitrogen oxide, measured by the method, belong to range of 0, 05-0, 50% of volume fraction. Method excludes aggressive affect of corrosion-active components on sensitive parts of chromatograph. Method can be used under industrial conditions for revealing factors influencing process of forming of nitrogen oxide at the stage of catalytic oxidation of ammonia and searching for optimal conditions for minimizing effluent of ammonia into atmosphere.

EFFECT: high reproduction; simplification; improved efficiency of operation.

3 ex

FIELD: oil and gas production.

SUBSTANCE: aim of invention is estimating expectations for oil and gas of oil-source rock areas. For that aim, sampled rock is treated to isolate organic substance soluble in organic solvents, after which organic substance is chromatographed to detect 4-methyldibenzothiophene and 1-methyldibenzothiophene. When ratio of 4- to 1-isomer exceeds 0.9 rock is regarded as ripened.

EFFECT: increased determination reliability and rapidity.

2 tbl

FIELD: physics.

SUBSTANCE: in the method, hard carrier with system of narrow pores and channels is kept under temperature below height of potential barriers for movement of at least one type of separated molecules.

EFFECT: higher efficiency.

4 dwg

Gas analyzer // 2267123

FIELD: investigating or analyzing materials.

SUBSTANCE: gas analyzer comprises chromatographic columns, detectors, unit for preparing air mounted inside the thermostat, unit for control and processing signals, member for sampling, switches of gas flows, pump for pumping gas mixture, and separating passages connected in parallel and provided with the check valve interposed between them. Each of the separating passages is made of absorbing and separating chromatographic columns connected in series, and the pump is connected to the input of the gas line through the electric valve. The gas analyzer can be made of two separating passages and low pressure chromatographic columns.

EFFECT: enhanced quality of analyzing.

2 cl, 1 dwg, 1 ex

FIELD: analytical methods.

SUBSTANCE: to determine methyl alcohol in water, sample to be assayed is preliminarily subjected to distillation with sulfuric acid added in amount required to provide its concentration in mixture to be distilled c(1/2 H2SO4) = 0.002 M, while strippings constitute 6-7% of the volume of sample. Stripped liquid is thrice rinsed with hexane or Nefras at 1:1 hexane (Nefras)-to-strippings ratio. Rinsed material is then introduced into packed column filled with diatomite modified with 1,2,3-tris(β-cyanoethoxy)propane having deposited fixed phase thereon, which phase is prepared by way of consecutively keeping glycerol each time for 4 h at ambient temperature, 100°C, 130°C, 160°C, and 200°C, and then for 8 h at 230°C and for 40 h at 200°C under nitrogen bubbling conditions. Calculation of methanol content is performed taking into consideration calibrating coefficient.

EFFECT: enabled determination of small concentrations of methyl alcohol in water with sufficient selectivity and reliability.

2 cl, 2 tbl, 6 ex

FIELD: analytical chemistry.

SUBSTANCE: invention relates to method for quantitative determination of thiotriazoline and pyracetam in complex drugs by high performance chromatography, wherein silicagel with grafted 3-(chlorodimethyl)-propyl-N-dodecylcarbamate having particle size of 5 mum is used as sorbent; and degassed 0.05 M aqueous solution of potassium dihydrophosphate is used as mobile phase. Mobile phase velocity is 1 ml/min, and column temperature is 30°C. Method of present invention makes it possible to determine content of two abovementioned active ingredients simultaneously.

EFFECT: simplified process of sample preparation.

3 ex, 3 tbl

FIELD: biotechnology, in particular content determination of polymer chitosan molecules, chitosan-chitine polymer molecules and molecules of chitosan-protein complex in finished form of chitosan.

SUBSTANCE: claimed method includes application of high performance chromatography column filled with polyvinylbenzene sorbent with refractometer detector. As eluent and for dissolving of chitosan preparation samples acetic acid aqueous solution is used. Chain-length distribution is determined on the base of first chromatography peak, and polymer molecular content is calculated on the base of area of first, second and third chromatography peaks, divided up to zero line and belonging to polymer chitosan molecules, chitosan-chitine polymer molecules and molecules of chitosan-protein complex, respectively. To calculate chain-length distribution of polymer chitosan molecules separately calibration curve is plotted using dextran polymer standards.

EFFECT: new effective method for determination of polymer chitosan molecules in chitosan preparations.

4 cl, 3 dwg

Express-chromatron // 2300764

FIELD: the invention refers to laboratory chromatographic devices for conducting high-speed chromatographic analysis.

SUBSTANCE: the express-chromatron has an injector, a chromatographic column located in a thermostat, a detector, an amplifier of the signal of the detector, an analog-digital converter, a control system, a pneumatic system. The column is fulfilled either in the shape of a short capillary column or either in the shape of a polycapillary column. The injector is fulfilled with possibility of introduction of the test for the time of 5-50 ms. The detector and the amplifier of its signal are fulfilled with possibility of ensuring constant time of no worse then 10-3 sec. The analog-digital converter is fulfilled with possibility of ensuring speed of no less then 200 measurements in a second.

EFFECT: ensures conducting high-speed chromatographic analysis.

11 cl, 2 dwg

Up!