CZ2013712A3 - Procedure and device for determining selected catalytic poisons in propylene - Google Patents

Abstract

Gas chromatographic determination of selected catalytic poisons in propylene involves injecting a sample containing at least 99% by volume of propylene, nitrogen and at least catalytic poisons CO, COS and CO.sub.2 with a flow rate of 3.2 ml / min. at a pressure of 200 to 300 kPa and heating to 50 to 65 degC, then propylene is separated from the sample at a pressure of 300 to 350 kPa in a first column for separation of COS and lower hydrocarbons, then the sample is heated at 30 to 40 deg. C. per minute to a temperature of 180 to 230 degC, then the sample is divided into two, then nitrogen from CO on the molecular sieve is separated from the first CO and nitrogen containing sample at a pressure of 250 to 300 kPa and the remaining catalytic the poisons in the second part of the sample are distributed at a pressure of 300 to 350 kPa in a second column for separation of COS and lower hydrocarbons and then both parts of the sample are evaluated by mass spectrometry. The propylene catalytic poisons apparatus comprises a metering device (1) connected to a COS and lower hydrocarbon separation column (4), the outlet of which is connected via a divider (3) to the propylene detector (5) and via a column divider (6). 8) for the separation of COS and lower hydrocarbons and into the molecular sieve (9). The columns (4, 8, 9) are placed in heating devices (2, 7). The molecular sieve outputs (9) and the column (8) are connected to a mass spectrometer (10).

Description

The present invention relates to a process and apparatus for the determination of selected catalytic poisons in propylene which adversely affect the activity of the catalyst and thus the polymerization of propylene. Selected catalytic poisons are CO, CO ₂ , COS, AsH _{3 and} NO.

BACKGROUND OF THE INVENTION

Propylene is one of the basic petrochemical raw materials. More than half of its production is used for the production of polypropylene. The process by which polypropylene is produced is called polymerization. This is a catalytic reaction. Catalysts are generally very sensitive to so-called catalytic poisons. Newly developed catalysts often have higher activity than previous ones. However, high activity is also associated with higher sensitivity to catalytic poisons. This means that the development of new catalysts is accompanied by efforts to reduce the content of catalytic poisons in propylene, otherwise there is a risk of catalyst degradation. Efforts to reduce catalytic poisons make it necessary to develop new analytical methods having a lower detection limit in order to determine lower levels of catalytic poisons in propylene.

One of the prior art methods for the determination of catalytic poisons in propylene is the so-called dry colorimetry [Thind, S. Analysis of Impurities in Polymer-grade Ethylene, Propylene and 1,3 Butadiene. Available January 31, 2013 at http://www.cianalytics.com/articles/low_level_impurity_analysis.pdf]. The procedure is based on the fact that when the analyzed gas passes through the detection tape impregnated with the reagent (or mixture of reagents), a colored spot appears on the tape. The higher the analyte concentration, the darker the color spot. The evaluation is done by measuring the darkness of the color spot and comparing it with the standards in the built-in calibration curve (internal calibration). The disadvantage of this procedure is the large volume of the dosed sample, non-separation of individual catalytic poisons and spectrophotometric detection. A significant disadvantage of this procedure is that it does not allow the determination of catalytic poisons of CO and CO ₂ .

Another prior art method for determining impurities in propylene is gas chromatography with mass detection [Feyerherm, F., Wason, J. Analysis of Trace Contaminants in High Purity Ethylene and Propylene Using GC / MS: Agilent Technologies / Wasson ECE Monomer Analyzer: Application; Library Agilent Technologies. Life sciences and chemical analysis. Available on 2013-01-31 at http://www.chem.agilent.com/Library/applications/5966-3240E.pdf]. The principle of the procedure is the separation of individual impurities and propylene with subsequent mass detection. This procedure allows for the determination of low concentrations of some hydrocarbons, sulfur compounds, arsine and phosphine after pre-pyreneil separation. The disadvantage of this procedure is that it does not allow the determination of COS below 10 nl / l. Another disadvantage is that it does not allow the determination of CO and CO2.

Another procedure for the determination of impurities in propylene [Peak Performer 1, Peak Laboratory's resource liqueurs. Available on 2013-01-31 at http://peaklaboratories.com/resources/datasheets/peak_performer_lrcp_datasheet.pdf] works on the principle of oxidation-reduction reaction followed by UV detection. The process utilizes a mercury oxide bed heated to a defined temperature. Passing a sample through this bed at a given temperature results in an oxidation-reduction reaction according to the equation

CO + HgO - * CO2 + Hg [1] and subsequent release of mercury vapors. In a photometric cell, its UV absorbance is measured, which is proportional to the CO content. The disadvantage of this procedure is that it is only applicable to the determination of two components, CO and hydrogen, but does not allow the determination of CO2, COS, AsFfi and NO. Another disadvantage of this process is the use of mercury, which is highly toxic. Another disadvantage is the use of UV detection, which is generally less sensitive

Another procedure for the determination of impurities in propylene [V.A.Krylov, O.Yu. Chemova, A.Yu. Sozin, A.P.Kotkov. Gas Chromatography / Mass Spectrometry Analysis of High Purity Arsine. Inorganic Materials 2011, Vol. 47, No. 14, s. 1534-1538] is also based on gas chromatography with mass detection, the disadvantage of which in this case is the determination of catalytic poisons only in arsine, not in propylene. Although this procedure makes it possible to determine silicon hydride (SiH4) and germanium hydride (GeH4), which are not commonly found in propylene.

Another existing process impurities determination is indeed intended for the determination of impurities, which are H _2, O2, Ar, N2, CO, CO2 and hydrocarbons, but in a highly pure silicon hydride (S1H4) [VM Vorotyntsev GM Mochalov, AK Matveev AV Malyshev IV Vorotyntsev. Determination of Trace Impurities of H2, O2, Ar, N2, CO, CO2 and Hydrocarbons in High-Purity Monosilane by Gas Chromatography, Journal of Analytical Chemistry, Vol. 58, 2003, pp, 156-159], Gas chromatography again proceeds.

The above disadvantages are eliminated by the process of determining selected catalyst poisons in propylene according to the invention.

SUMMARY OF THE INVENTION

The procedure for the determination of selected catalytic poisons in propylene by gas chromatography is characterized by. A sample of between 100 and 300 μ 300, containing at least 99% by volume of propylene, nitrogen and at least catalytic CO poisons. COS and CO ₂ , injected at a flow rate of 3.2 ml / min at 200-300 kPa and heated to 50-65 ° C, then propylene was separated from the sample at 300-350 kPa in the first COS and lower hydrocarbon separation column then the sample is heated at a rate of 30 to 40 ° C per minute to a temperature of 180 to 230 ° C, then the sample is divided into two parts, then nitrogen is separated from the first part of the sample containing CO and nitrogen at 250 to 300 kPa The CO on a 0.5 nm molecular sieve and the remaining catalytic poisons in the second portion of the sample are split at 300-350 kPa in a second column for separating COS and lower hydrocarbons, and then both parts of the sample are evaluated by mass spectrometry.

A preferred method for the determination of selected catalytic poisons in propylene by gas chromatography is characterized in that the sample comprises at least one additional catalytic poison selected from the group consisting of AsH 2? and NO.

Apparatus for determining selected catalytic poisons in propylene by gas chromatography is characterized in that the sample dosing device is connected to an inlet of a first COS and lower hydrocarbon stream column located in a first heating device whose outlet is connected to an inlet of a first divider, one outlet of it is connected to an inlet to the propylene detector and a second outlet to an inlet to a second divider, one outlet to the inlet of a second COS and lower hydrocarbon separation column and the other to an inlet of 0.5 nm molecular sieve, wherein the second COS and lower hydrocarbon separation column and the molecular sieve column are located in a second heating device, the output of the second COS and lower hydrocarbon separation column and the molecular sieve column are connected to the mass spectrometer inlet, The columns have an internal diameter of 0.32 mm and a length of 30 to 60 m.

The procedure for the determination of selected catalytic poisons in propylene according to the invention makes it possible to determine CO, CO? and COS together with ASH3 and / or NO. In contrast to online-based methods, the procedure for determining selected catalytic poisons in propylene according to the invention is customizable according to current needs. For example, if it is no longer necessary to determine COS in propylene, which is eluted as the last component from the catalytic poisons of interest, the procedure may be modified by reducing the analysis time.

If the sample contains CO, CO ₂ , COS, ASH 3 and NO, nitrogen, CO is distributed on the molecular sieve in the first part of the sample in the procedure for determining selected catalytic poisons in propylene according to the invention. The other catalytic poisons, CO ₂ , COS, ASH 3 and NO, are separated in a second column for the separation of COS and lower hydrocarbons.

The process for the determination of selected catalytic poisons in propylene according to the invention makes it possible to achieve lower detection limits than the prior art methods, which is necessary in particular in view of the newly developed polymerization catalysts sensitive to low concentrations of catalytic poisons.

Clarification of drawings- »

BRIEF DESCRIPTION OF THE DRAWINGS The following drawings are shown in order to illustrate the invention in greater detail:

Figure A shows the spectrogram of propylene containing four catalytic poisons, namely CO, CO 2, COS and AsH ₃ .

Figure 1 shows a diagram of a device for determining selected catalytic poisons in propylene.

Examples of embodiments of the invention

Example 1

A sample of 100 or 200 μΐ, containing 99,5% by volume of propylene, nitrogen and CO, COS and CO2 catalytic poisons, is injected at a flow rate of 3,2 ml / min at 200 kPa and heated to 50 ° C. Then, propylene is separated from the sample at a pressure of 300 kPa from the catalytic poisons and nitrogen in the first column (for COS and lower hydrocarbon separation), and then the sample containing the catalytic poisons and nitrogen is heated at 30 ° C per minute to 180 ° C. The sample is divided into two portions at a time of 2.3 minutes after injection and from a first portion of the sample containing CO and nitrogen, at a pressure of 250 kPa, nitrogen is separated from CO on a molecular sieve (9.) having a particle size of 0.5 nm. At 2.4 minutes after injection, the second portion of the sample containing the remaining catalytic poisons at 300 kPa pressure begins to separate into individual catalytic poisons in the second column (8 µL for COS and lower hydrocarbon separation. At 4.6 minutes after injection, both portions sample and then evaluated by mass spectrometry.

Table 1 - Results of determination of selected catalytic poisons in propylene

determined component WHAT co ₂ WHAT WITH concentration [nl / 1] 45 68 6.5

Example 2

100 μΐ sample containing 99.5% by volume of propylene, nitrogen and catalytic poisons CO, COS, CO? and AsH ₃ , was injected at a flow rate of 3.2 ml / min at 200 kPa and heated to 60 ° C. Then propylene is separated from the catalyst poisons and nitrogen in a first column (4) for separating COS and lower hydrocarbons from the sample at a pressure of 350 kPa. Then the sample containing the catalytic poisons and nitrogen is heated at a temperature of 35 ° C per minute to 200 ° C. Then, the sample is divided into two parts at 2.1 minutes after injection. From a first portion of the sample containing CO and nitrogen, at a pressure of 270 kPa, nitrogen is separated from CO on a molecular sieve (9) having a particle size of 0.5 nm. At 2.2 minutes after injection, the second portion of the sample containing the remaining catalytic poisons at 350 kPa pressure begins to separate into individual catalytic poisons in the second column (8j for COS and lower hydrocarbon separation). parts of the sample are joined and then evaluated by mass spectrometry.

Table 2 - Results of determination of selected catalytic poisons in propylene:

determined component WHAT CO ₂ WHAT WITH AsH ₃ concentration [nl / 1] 55 48 5.5 65

(x1.000,000)

44.00

1.00

0.75 ro

C c <D c 0.500.25

76.00

28.00

CO ₂ 48 ppb CO 50 ppb AsH ₃ 65 ppb COS 10 ppb /

0.00

3.25 3.50 3.75 4.00

4.25 4.50 4.75

5.00

5.25 5.50 5.75 retention time t _R [min]

Figure A: Analysis of propylene containing four catalytic poisons - CO, CO2, COS and AsH ₃

Example 3

A 300 μΐ sample containing 99.8% by volume of propylene, nitrogen and CO, COS, CO2 and NO catalyst poisons is injected at a flow rate of 3.2 ml / min at 200 kPa and heated to 65 ° C. Then propylene is separated from the catalyst poisons and nitrogen in the first column (4) for separating COS and lower hydrocarbons from the sample at 320 kPa. Then, the sample containing the catalytic poisons and nitrogen is heated at a temperature of 40 ° C per minute to 230 ° C. Then, within 4.6 minutes after injection, the sample is divided into two parts. From the first part of the sample, containing CO, NO and nitrogen, nitrogen, NO and CO are separated at a pressure of 300 kPa on a molecular sieve (9) having a particle size of 0.5 nm. During

4.8 minutes after injection, the second portion of the sample, containing the remaining catalytic poisons, at 320 kPa pressure, begins to separate into individual catalytic poisons in the second column (8) for separating the COS and lower hydrocarbons. At 6.0 minutes after injection, both parts of the sample were pooled and then evaluated by mass spectrometry.

Table 3 - Results of the determination of selected catalytic poisons in propylene

determined component WHAT CO ₂ WHAT WITH NO concentration [nl / 1] 95 362 9.5 168

Example 4

A sample of 100 or 200 μΐ, containing 99,5% by volume of propylene, nitrogen and catalytic poisons of CO, COS, CO2.NO and AsH ₃ , is injected at a flow rate of 3,2 ml / min at 200 kPa and heated to 55 ° C. Deň: 32 ° C. Then propylene is separated from the catalyst poisons and nitrogen in the first column (4) for separating COS and lower hydrocarbons from the sample at a pressure of 330 kPa. Then the sample containing the catalytic poisons and nitrogen is heated at a temperature of 35 ° C per minute to 220 ° C. The sample is then divided into two parts at 2.3 minutes after injection. From the first portion of the sample, containing CO, NO and nitrogen, nitrogen, NO and CO are separated at a pressure of 300 kPa on a molecular sieve (9) having a particle size of 0.5 nm. At 2.4 minutes after the injection, the second portion of the sample containing the remaining catalytic poisons at 330 kPa pressure begins to separate into individual catalytic poisons in the second column (8J for COS and lower hydrocarbon separation). parts of the sample are joined and then evaluated by mass spectrometry.

Table 4 - Results of determination of selected catalytic poisons in propylene

determined component WHAT CO ₂ WHAT WITH NO AsH ₃ concentration [nl / 1] 72 225 4.2 110 60

Example 5

The apparatus for the determination of selected catalytic poisons in propylene by gas chromatography comprises a sample dosing device (1) which is a dosing loop. The outlet of the feed loop is connected to the inlet of the first column (4 > GS-GasPro of Agilent Technologies for COS and lower hydrocarbon separation) This column (4) is equipped with a first heating device (2). connected to the inlet to the first divider (3) which is a three-way valve One outlet of the first divider (3) is connected to the inlet to the propylene detector (5) The second outlet of the first divider (3) is connected to the inlet to the second divider (6) One outlet of the second splitter (6) is connected to an Molsieve 5A PLOT column from Agilent Technologies with a molecular sieve (9) having a particle size of 0.5 nm, an inner diameter of 0.32 mm and a length of 30 m. The second outlet of the second divider (6) is connected to the inlet of the second column (8j for COS and lower hydrocarbons separation). The molecular sieve column (9) and the second column (8 / for COS and lower hydrocarbons separation) are equipped with a second heater. m means (7). The output from the column with a molecular sieve (9) and the outlet of the second column (8j for dividing COS and lower hydrocarbons are connected to the input of the mass spectrometer (10). Both COS and lower hydrocarbon separation columns (4, 8,) have an inner diameter of 0.32 mm and a length of 30 or 60 m.

Example 6

The apparatus for the determination of selected catalytic poisons in propylene by gas chromatography comprises a pressure reducing valve for stabilizing the pressure in the sample dosing device (1), which is a dosing loop. The pressure reducing valve is connected to the first outlet of the dosing device (1). A second outlet of the metering device (1) is connected to the inlet of a first column (4) for separating COS and lower hydrocarbons having an internal diameter of 0.32 mm and a length of 60 m. This column (4) is equipped with a first heating device (2). The outlet of the first column (4) is connected to the inlet to the first divider (3y which is a three-way valve. One outlet of the first divider (3) is connected to the inlet to the propylene detector (5). One outlet of the second separator (6J) is connected to the inlet of a molecular sieve column (9) having a particle size of 0.5 nm, an inner diameter of 0.32 mm and a length of 30 m. The second outlet of the second divider (6 is connected to the inlet to the second column (8) 'for separating COS and lower hydrocarbons with an internal diameter of 0.32 mm and a length of 30 m. Molecular sieve column (9) and second column (8) for COS separation and lower hydrocarbons are equipped with a second heating device (7) The exit of the molecular sieve column (9 /) and the second COS separation column (8) are connected to the mass spectrometer (10) inlet. Both columns (4, 8) for cannons COS and lower hydrocarbons have an internal diameter of 0.32 mm and a length of 30 or 60 m.

Industrial applicability

The process and apparatus for the determination of selected catalytic poisons in propylene are industrially applicable in the production of polypropylene to control its quality.

Claims (3)

PATENT CLAIMS Method for the determination of selected catalytic poisons in propylene by gas chromatography, characterized in that a sample having a volume of 100 to 300 µl containing at least 99% by volume of propylene, nitrogen and at least catalytic poisons of CO, COS and CO2 is injected at a flow rate of 3.2 ml / min at 200 to 300 kPa and heated to 50 to 65 ° C, then propylene is separated from the sample at 300 to 350 kPa in the first COS and lower hydrocarbon separation column, then the sample is heated at a rate of 30 to 40 ° C per minute to a temperature of 180 to 230 ° C, then the sample is divided into two parts, then nitrogen is separated from the CO on a molecular sieve with a particle size of 0.5 at a pressure of 250 to 300 kPa from the first part of the sample containing CO and nitrogen. nm and the remaining catalytic poisons in the second portion of the sample are separated at a pressure of 300 to 350 kPa in a second column for separating COS and lower hydrocarbons, and then both parts of the sample are evaluated by mass spectrometry. The method of claim 1, wherein the sample comprises at least one additional catalytic poison selected from the group consisting of ASH 3 and NO. Device for carrying out the process according to one of claims 1 to 2, characterized in that the sample dosing device (1) is connected to the inlet of the first COS and lower hydrocarbon separation column (4) located in the first heating device (2), whose output is connected to an inlet to a first divider (3), one output of which is connected to an inlet to a propylene detector (5) and a second output to an input to a second divider (6), one of which is connected to an inlet to a second column (8) ) for separating COS and lower hydrocarbons and a second outlet to enter a molecular sieve column (9) with a particle size of 0.5 nm, the second column (8) for separating COS and lower hydrocarbons and a molecular sieve column (9) are located in a second heating device (7), the outlet of the second COS and lower hydrocarbon separation column (8) and the outlet of the molecular sieve column (9) are connected to the mass input The columns (4, 8, 9) have an internal diameter of 0.32 mm and a length of 30 to 60 m.