GB/T 18612-2011Determination of organic chloride content in crude oil (English PDF)

4.1 Reagents and materials

Unless otherwise specified in the analysis using only analytical reagent.

4.1.1 potassium hydroxide (KOH).

Warning --- may cause severe skin burns.

4.1.2 acetone (CH3COCH3).

Warning --- flammable and may cause fire, harmful to health.

4.1.3 toluene (C6H5CH3).

Warning --- flammable, harmful to health.

4.1.4 Water. in line with GB/T 6682 in two water requirements.

4.1.5 potassium hydroxide solution. c (KOH) = 1mol/L.

4.1.6 filter paper.

4.2 Instrument

4.2.1 round-bottomed distillation flask. heat-resistant glass, volume 1L, short bottleneck and has a 24/40 ground glass outside interface.

4.2.2 T-type takeover. heat-resistant glass, with a branch pipe 75 °, with 24/40 ground glass interface.

4.2.3 Thermometer. temperature range of 0 °C ~ 300 °C, the minimum scale of 1 °C.

4.2.4 Thermometer Interface. heat-resistant glass, with 24/40 ground glass inside interface.

4.2.5 Straight condenser. heat-resistant glass, 300mm, with a 24/40 ground glass interface.

4.2.6 evacuated Interface. heat-resistant glass, bent 105 °, with a 24/40 ground glass interface.

4.2.7 receiving cylinder. heat-resistant glass, the volume of 250mL, with a 24/40 ground glass outside interface.

4.2.8 Metal clip. for the 24th ground glass interfaces, stainless steel.

4.2.9 The cooling bath. the volume of 4L.

4.2.10 brass. for heat exchange cooling condensate, an outer diameter of 6.4mm, the length of 3m.

4.2.11 electric heating mantle. volume 1L, 0W ~ 1000W adjustable.

4.2.12 electronic balance. accurate to 0.01g.

4.3 Sampling

This standard should be GB/T 4756 or SY/T 5317 to obtain a representative sample.

4.4 Preparation of the sample

4.4.1 All glassware should be washed successively with toluene and acetone, and then dried with a stream of dry nitrogen. Weigh and record the round-bottomed flask and then the reception quality of the cylinder. Install glass distillation apparatus, sealed with Vaseline all interfaces, then the metal clip it interfaces, to prevent loosening. in when you install a thermometer, see GB/T 6536 Fig. 1, adjusted T-takeover position within the thermometer, so that the bottom end of the connection capillary thermometer cold T-takeover highest level of the bottom wall of the condenser.

4.4.2 The copper tube is wound into a coil, mounted inside the cooling bath, cooling bath in the center of the cylinder to make room for the reception. PTFE tube Brass reels one end connected to a water source, the lower branch pipe connected to the other end of the straight tube condenser of the condenser bushing on the branch pipe connected to the drain Place. The mixture was cooled with ice-water bath was filled, circulating open water, the condenser temperature should be kept below 10 °C.

4.4.3 The crude oil was added about 500mL weighed round bottom flask, weigh and record crude oil quality, accurate to 0.1g. The flask with steam Distillate device is connected, is placed in an electric heating mantle, the reception has been weighing on the cylinder below the outlet distillate, turn power electric heating mantle, distillation.

Distillation process, by regulating the electric heating mantle knob to control distillation rate of about 5mL/min. When the thermometer reading reaches 204 °C, Receiving cylinder removed, distillation was stopped. Weigh and record the distillate quality material, accurate to 0.1g.

4.4.4 The naphtha fraction is transferred from the receiving cylinder to a separatory funnel, potassium hydroxide solution with an equal volume (4.1.5) washed three times with oscillation, Removing hydrogen sulfide, then with an equal volume of water (4.1.4) oscillation washed three times to remove traces of inorganic chloride. Naphtha distillates washed Sub-filter to remove excess water and store in a clean glass jar and set aside.

4.5 Calculation Results

4.5.1 naphtha fraction mass fraction f, expressed in%, according to equation (1).

f = mnmc

Where.

Numerical mn --- collected naphtha fraction of the mass in grams (g);

Quality mc --- crude oil values in grams (g).

4.5.2 extracted with a known amount of mass 10mL 10mL volumetric flask naphtha fraction, weighed to the nearest 0.1g. The density of the naphtha fraction D, Values in grams per milliliter (g/mL) said, according to the formula (2).

D = mV

Where.

Numerical m --- naphtha fraction of the mass in grams (g);

Numerical V --- naphtha fraction of the volume, in milliliters (mL).

5.1 Reagents and materials

Unless otherwise specified in the analysis using only analytical reagent.

5.1.1 Silver nitrate (AgNO3).

5.1.2 nitric acid (HNO3).

Warning --- corrosive and may cause severe skin burns.

5.1.3 isopropanol ((CH3) 2CHOH).

Warning --- flammable, harmful to health.

5.1.4 iso-octane (C8H18). 2,2,4- trimethyl pentane.

Warning --- flammable, harmful to health.

5.1.5 biphenyl sodium (C12H10Na). using 15mL plastic bottle, a plastic bottle using the full dose of each test, each Plastic bottles are active 13mg ~ 15mg of sodium. Sodium biphenyl reagent should be stored at low temperatures, but not frozen. Prior to use, Reagent heated to about 50 °C, sufficiently shaken to ensure homogeneity.

5.1.6 standard silver nitrate solution. c (AgNO3) = 0.01mol/L.

5.1.7 nitric acid solution. c (HNO3) = 5mol/L. The 160mL nitrate (5.1.2) was added to 200mL water (4.1.4), and then diluted to 500mL.

5.1.8 Congo red.

5.2 Instrument

5.2.1 General glass electrode. When repeatedly using an electrode, the electrode should be weekly washed once with chromic acid lotion, or by other strong oxidizing Agent lotion.

Warning --- chromic acid lotion is a strong oxidant, can cause severe burns, cancer.

5.2.2 silver - chloride electrode.

5.2.3 potentiometric titrator. with a capacity not greater than 5mL burette and magnetic stirrer.

5.2.4 Electronic balance. accurate to 0.01mg.

5.3 Analysis Steps

5.3.1 Prior to the determination of chloride, all glassware should be washed with water, then rinsed with acetone.

5.3.2 50mL toluene injection volume of 250mL separating funnel, and adding a plastic bottle biphenyl sodium (5.1.5), mixed well Together, then add the sample obtained by the 4.4.4 about 30g, accurate to 0.1g. The funnel was Gaiyan and mixed solution or suspension should form Now blue-green, or should be added sodium biphenyl a plastic bottle until a solution or suspension of blue-green.

5.3.3 After the solution was mixed well, then placed 10min, waiting for the end of the completion of the reaction, and then successively added 2mL isopropanol, gently open Shaken until the solution color from blue to green to colorless. Then added 20mL of water and 10mL of nitric acid solution (5.1.7) and gently shake Do not swing through the cock relief. Congo red test paper with the aqueous phase, if there is no paper turns blue, then added a solution of nitric acid 5mL, straight Blue paper to date.

5.3.4 The aqueous phase was transferred to another isooctane containing 50mL separatory funnel, shake well after the aqueous phase was transferred to a 250mL burning Cup. Has been used a few drops of nitric acid solution 25mL water sample containing isooctane secondary extraction, the aqueous phase is also transferred to 250mL beaker, the beaker was heated on a hot plate in an aqueous solution was evaporated to 25mL ~ 30mL. Heating plate temperature should be maintained at Below the boiling point of the solution, the solution to avoid boiling.

5.3.5 After cooling the solution was added 100mL of acetone, potentiometric titration with silver nitrate standard solution (5.1.6). If you use automatic electrical Bit titrator is used Semimicro 5mL burette; if you are using a manually operated titrator, the semi-micro 5mL burette should be accurate Second place after the decimal point.

5.3.6 With manual titration, the titration end point may be determined by the method of drawing the titration curve, the titration curve represents the measured potential and consumption Silver nitrate solution corresponding relationship between the volume; When using automatic titration, the titration end point is the inflection point of the titration curve.

5.3.7 should be blank, blank solution should include all reagents except the sample.

5.4 Calculation Results

5.4.1 naphtha fraction of organic chlorine content of the mass fraction wn and its value in micrograms per gram (µg/g) expressed by the formula (3) Calculated.

(V1-V2) c × 35460

Where.

Value Vl --- titration volume when consumed sample standard silver nitrate solution, in milliliters (mL of);

The value of the volume V2 of the blank test --- consumed standard silver nitrate solution, in milliliters (mL of);

Numerical c --- silver nitrate standard solution molar concentration, measured in moles per liter (mol/L);

Numerical mass m1 --- sample in grams (g);

35460 --- conversion factor.

5.4.2 Crude organic chloride content in mass fraction w and its value in micrograms per gram (µg/g) expressed by the formula (4) Calculated.

w = wn × f (4)

Where.

wn --- naphtha fraction of the value of organic chloride content (5.4.1), in micrograms per gram (µg/g);

f --- naphtha fraction mass fraction (4.5.1).

5.5 Precision and departing

5.5.1 Precision

5.5.1.1 Repeatability (r)

In the same laboratory by the same operator using the same equipment, according to the provisions of the standard operation, and in a short time of each other the same sample Independent tests conducted two independent test results obtained absolute difference does not exceed the probability according to equation (5) to calculate the value of 95%.

r = 0.32 (X 0.33) 0.644 (5) where.

The arithmetic average of crude oil of organic chloride content X --- twice as measured in micrograms per gram (µg/g).

5.5.1.2 Reproducibility (R)

In different laboratories by different operators using different equipment, according to the provisions of the standard operation, independent of each other into the same sample the absolute difference between two independent test results obtained in the test line does not exceed the probability according to equation (6) to calculate the value of 95%.

R = 0.7 (X 0.33) 0.644 (6) where.

The arithmetic average of crude oil of organic chloride content X --- twice as measured in micrograms per gram (µg/g).

5.5.2 Deviate

Crude oil was added to a variety of known content of various organic chlorine compounds, conduct recovery test. The amount of deviation shown in Fig.

An organic chlorine content of a recovery curve

6.1 Reagents and materials

Unless otherwise specified in the analysis using only analytical reagent.

6.1.1 Reaction gas. oxygen, high-purity grade.

6.1.2 Carrier gas. argon, helium, nitrogen or carbon dioxide, high purity grade.

6.1.3 silver acetate (CH3COOAg).

6.1.4 glacial acetic acid (CH3COOH).

6.1.5 chlorobenzene (C6H5Cl).

6.1.6 acetic acid solution. volume fraction of 70%. The 300mL water (4.1.4) and 700mL glacial acetic acid (6.1.4) and mix well.

6.1.7 chlorine standard stock solution. a chlorine content of 1000mg/L. Accurately weigh 1.587g chlorobenzene (6.1.5) in 500mL volumetric flask Isooctane (5.1.4) diluted to the mark.

6.1.8 chlorine standard solution. chlorine content of 10mg/L. Pipette 1.0mL chlorine standard stock solution (6.1.7) in 100mL volumetric flask Isooctane diluted to the mark.

6.2 Instrument

6.2.1 cracker. thermostat can be 800 °C.

6.2.2 quartz pyrolysis tube. the inlet section should be used for the injection syringe septum, and the reaction gas can be introduced into the intake manifold and a carrier gas.

Sample inlet section can be completely evaporated, the carrier gas evaporated sample loading oxidation zone, in the oxidation zone with the reaction gas mixture and combustion, tube the oxidation zone should have sufficient space to ensure complete combustion of the sample.

6.2.3 Titration pool. comprises detecting changes in the concentration of silver ion sensing - reference to the electrode; to maintain a constant concentration of silver ion generator Yang - cathode on; vias imported gas obtained from the pyrolysis tube samples. Sensing electrode, a reference electrode and an anode made of silver electrode generator, overcast Pole made of platinum wire. Reference electrode immersed in a saturated solution of silver acetate, acetic acid electrolyte solution (6.1.6).

6.2.4 microcoulometry. a continuously adjustable gain and bias control, the sensor is able to measure - the difference between the reference potential electrode pair ratio and the potential difference and the bias potential is compared, then the comparison value is applied to the larger generator male - cathode pair titration. The output signal microcoulometry Proportional to the current generated. Microcoulometry may have a digital instrument and electrical systems, the output signal is directly converted into organic chlorine the number of nanograms or micrograms.

6.2.5 Sample syringe. volume of 50µL micro syringe. Can accurately sample 5µL ~ 50µL injected into the pyrolysis tube.

Recommended 75mm ~ 150mm long needle, the sample is injected into the cracking tubes in the inlet section of about 500 deg.] C.

6.2.6 Injector. Recommended injection speed does not exceed 0.5µL/s.

6.3 Analysis Steps

6.3.1 The device according to the manufacturer's instructions to install the equipment.

6.3.2 Typical operating conditions are as follows.

The reaction gas (O2) flow rate. 160mL/min Carrier gas flow rate. 40mL/min Oven temperature.

Entrance. 700 °C

Middle and outlet. 800 °C Microcoulometry.

Bias. 240mV ~ 265mV

Gain. about 1200

6.3.3 sample syringe 30µL secondary distilled or deionized water injected directly into the titration cell, increase or decrease the bias, making due the total integrated value of the minimum dilution effect arising.

6.3.4 extracted with 50µL 30µL ~ 40µL syringe samples obtained from the 4.4.4, carefully remove air bubbles, withdraw the needle bar so that the meniscus 5µL reached the lowest point at the other end of the liquid column syringe record readings. After injection of the sample, pull out the syringe, then withdraw the needle bar so that the recess Level the lowest point reached 5µL at the other end of the liquid column syringe record readings. Difference between the two readings is injected sample volume.

6.3.5 weighing method can also be used, namely the quality of weighing the syringe before and after injection of the sample injection, accurate to 0.01mg, of poor quality that is twice for the quality of the sample injection. This method is more accurate than the volume of the injection method.

6.3.6 not to exceed 0.5µL/s speed of the sample is injected into the pyrolysis tube.

6.3.7 When the organic chlorine content of less than 5µg/g, the needle septum blank impact will be more significant. To improve accuracy, place the syringe needle Insert cracking tube inlet section, until the needle septum is blank titration after the injection of the sample or chlorine standard solution.

6.3.8 When the organic chlorine content of greater than 25µg/g, only the injection 5.0µL.

6.3.9 Each 4h chlorine standard solution (6.1.8) was measured to check the system recovery, system recovery should be more than 85%.

6.3.10 chlorine standard solution measurement is repeated at least three times.

6.3.11 daily with isooctane blank inspection system, the sample should be the standard solution and chlorine measurement data system subtracts blank, empty when the needle septum After White was titrated (6.3.7), system blank should be less than 0.2µg/g.

6.4 Calculation Results

6.4.1 naphtha fraction of organic chlorine content is calculated as follows.

6.4.1.1 direct readout of the number of nanograms of microcoulometry chlorine, organic chlorine naphtha fraction mass fraction wn and its value to micro G per gram (µg/g) expressed by the formula (7) or (8) Calculated.

wn = A1-A0 (V) (D) (RF) (7) wn = A1-A0 (m2) (RF) (8) RF = A2-A0 (V) (D) (CS) where.

A1 --- integral value of the sample, in units of nanograms (ng);

A0 --- blank integral value in units of nanograms (ng);

A2 --- chlorine standard solution of integral value in units of nanograms (ng);

Numerical V --- sample injection volume, in units of microliters (µL);

--- The D value naphtha fraction density in grams per milliliter (g/mL);

RF --- recoveries, standard integrated value of the integral value minus blank, standard chlorine content divided by injection;

Quality m2 --- sample value, in milligrams (mg);

Numerical CS --- chlorine standard solution of organic chlorine content, expressed in milligrams per liter (mg/L).

6.4.1.2 For only the analog signal to microcoulometry recorder on naphtha fraction of organic chlorine content of the mass fraction wn and its value in micrograms per gram (µg/g) expressed by the formula (9) Calculated.

(A) (S) (0.367)

(R) (Y) (m) (RF) -B

Where.

A --- suitable area readings expressed in units;

S --- recorder full-scale sensitivity, in millivolts (mV);

0.367 =

(35.45g/eq) (10-3V/mV) (106µg/g) (96500C/eq) R --- Resistance in ohms (ohm);

Y --- per second - on the recorder unit of area per equivalent area of a full-scale response;

Numerical m --- sample mass, expressed in grams (g);

RF --- recoveries;

B --- system blank, in micrograms per gram (µg/g).

6.4.2 Crude organic chloride content in mass fraction w and its value in micrograms per gram (µg/g) expressed by the formula (10) Calculated.

w = wn × f (10)

Where.

wn --- naphtha fraction of the value of organic chloride content (6.4.1), in micrograms per gram (µg/g);

f --- naphtha fraction mass fraction (4.5.1).

6.5 Precision and departing

6.5.1 Precision

6.5.1.1 Repeatability (r)

In the same laboratory by the same operator using the same equipment, according to the provisions of the standard operation, and in a short time of each other the same sample Independent tests conducted two independent test results obtained absolute difference does not exceed the probability according to equation (11) to calculate the value of 95%.

r = 1.01 (X-0.17) 0.467 (11) where.

The arithmetic mean of the organic chlorine content X --- twice as measured in micrograms per gram (µg/g).

6.5.1.2 Reproducibility (R)

In different laboratories by different operators using different equipment, according to the provisions of the standard operation, independent of each other into the same sample the absolute difference between two independent test results obtained in the test line does not exceed the probability according to equation (12) to calculate the value of 95%.

R = 1.32 (X-0.17) 0.467 (12) where.

The arithmetic mean of the organic chlorine content X --- twice as measured in micrograms per gram (µg/g).

6.5.2 Deviate

See 5.5.2.