– Titrant: c(AgNO3) = 0.02 mol/L (see Method 16)
– Nitric acid: c(HNO3) = approx. 5 mol/L. w(HNO3) = 65% is diluted 1:1 with dist.
H2O
– Solvents: pentane and isopropanol
The catalyst tablets must be freed from hydrocarbon residues. This is done by filling the tablets into a chromatography column (L approx. 30 cm, D approx. 1.5 cm). 100 mL pentane per 10 cm3 catalyst is percolated through the column with a flow rate of 5 mL/min. The cleaned catalyst is dried at 100 °C for 30 min and then ground up (particle size 200...400 mesh). The powder is then dried in a vacuum desiccator for a further hour.
The titer of the AgNO3 solution has already been determined in Method 16 (com- mon variable C35).
A suitable amount of prepared sample is weighed into a 150 mL beaker, treated with 50 mL dist. H2O and 5 mL HNO3 and the chloride is extracted for 15 min by stirring. Then 50 mL isopropanol is added and the solution titrated with c(AgNO3)
= 0.02 mol/L.
Calculation
Method 17 – Chloride in water and fouled catalysts
Remarks
1 mL c(AgNO3) = 0.02 mol/L corresponds to 0.709 mg Cl–
% chloride = EP1 x C01 x C35 / C00 / C02
EP1 = titrant consumption up to the endpoint, in mL C00 = sample weight in g
C01 = 0.709 C02 = 10 (for %)
C35 = titer of the AgNO3 solution
The above calculation gives the content in the whole catalyst. To calculate the chloride content in the inorganic catalyst fraction its carbon fraction must be deter- mined separately and included in the calculation. The chloride values are then approx. 8...12% higher.
Method parameters & calculation Titration curve
Methods 17.1 & 17.2 & 17.3 (example)
Method 17 – Chloride in water and fouled catalysts
'pa785 DMP Titrino 02287 785.0010 date 2000-11-22 time 14:15 0 DET U M17.1
parameters
>titration parameters
meas.pt.density 4 min.incr. 10.0 àl dos.rate max. ml/min signal drift 30 mV/min equilibr.time 32 s start V: OFF pause 0 s meas.input: 1 temperature 25.0 °C
>stop conditions
stop V: abs.
stop V 10 ml stop U OFF mV stop EP 9 filling rate max. ml/min
>statistics
status: OFF
>evaluation
EPC 5 EP recognition: all fix EP1 at U OFF mV pK/HNP: OFF
>preselections
req.ident: id1 req.smpl size: all limit smpl size: OFF activate pulse: OFF ---
'de785 DMP Titrino 02287 785.0010 date 2000-11-22 time 14:15
DET U M17.1 def>formula
Chloride=EP1*C01*C02*C35/C00 RS1 text Chloride RS1 decimal places 1 RS1 unit: mg/L RS1 limit control: OFF
>silo calculations
match id: OFF
>common variables
>report
report COM1:full;curve;
>mean MN1=RS1
>temporary variables ---
'cf785 DMP Titrino 02287 785.0010 date 2000-11-22 time 14:15
DET U M17.1 C-fmla
C01 0.3545 C02 1000 ---
Method 18 – Organically bound chlorine in crude oil
Recommended accessories
General
Definition Reagents
Sample preparation
• 6.3014.213 Exchange Unit, 10 mL
• 6.0430.100 Ag Titrode with Ag2S coating and 6.2104.020 electrode cable
• Separating funnel (250 mL)
Organically bound chlorine in crude oil products decomposes at high tempera- tures and forms hydrochloric acid, which then has a very corrosive effect on, for example, distillation columns. It is therefore important to know and to be able to determine the amount of organically bound chlorine in these products. The method is suitable for crude oil and liquid petrochemical products. The sample is first freed from sulfur compounds and inorganic chlorides by distillation and subsequent washing so that only the organically bound chlorine fraction is present. These preparatory steps do not form part of Method 18 and must be taken from ASTM D 4929-89.
The organically bound chlorine is converted with sodium* in the toluene phase to form inorganic NaCl. After destruction of the excess sodium with isopropanol the NaCl is extracted into an aqueous phase and determined in this phase by a poten- tiometric AgNO3 titration.
* Metallic sodium is difficult to handle and also cannot be distributed sufficiently well in the organic phase. The conversion is therefore carried out with a similarly reactive sodium biphenyl solution.
Organically bound chlorine in mg / kg sample (ppm).
– Titrant: c(AgNO3) = 0.01 mol/L (preparation and titer determination see Method 16)
– Biphenyl sodium complex solution: in ampoules, e.g. Fluka No. 14446 – Nitric acid: c(HNO3) = approx. 5 mol/L. 65% HNO3 : dist. H2O = 1:1
– Solvents: all chloride-free. Acetone, isooctane, isopropanol, toluene, ultrapure water
– Indicator solution: methyl orange, 1% in dist. H2O
50 mL toluene is placed in a separating funnel. One ampoule of biphenyl sodium is dissolved in it by swirling the contents; the solution is then treated with approx.
30 g sample distillate. The funnel is sealed with the stopper and the contents swirled about – the solution/emulsion should now have a blue-green color. If this is not the case then the contents of a further biphenyl sodium ampoule are added.
After mixing, the solution/emulsion is allowed to stand for 10 min in order to con- vert all the organochlorine. 2 mL isopropanol is then added and the open separat- ing funnel is swirled about until the blue-green color has disappeared. This indi- cates that there is no more excess sodium. The funnel is sealed again and shaken.
The stopper is removed from time to time in order to release the pressure. 20 mL ultrapure water and 10 mL HNO3 are added, the separating funnel is sealed and shaken thoroughly (the pressure is released from time to time). A few drops of indicator solution are added and the solution is briefly shaken. The indicator should turn red to show that the aqueous phase is acidic. If it remains yellow then HNO3 is added and the contents shaken until the indicator turns red.
Method 18 – Organically bound chlorine in crude oil
Analysis
Calculation
Remarks
Literature The aqueous phase is run off into a second separating funnel, treated with 50 mL
isooctane and thoroughly shaken. After separation the aqueous phase is run off into a 250 mL beaker. The isooctane is extracted a second time with 25 mL ultrapure water and a few drops of HNO3 and the aqueous phase added to the first extract in the beaker.
The extracts are then evaporated to give a volume of approx. 30 mL. Do not evapo- rate to less than 30 mL as otherwise chloride will be lost!
In the same way, but without sample, a blank solution is made up and treated (common variable C35). This determines the chloride content of the reagents used.
The titer of the AgNO3 has already been determined in Method 16 (common vari- able C35).
The cooled extraction solution is treated with 100 mL acetone and the solution is titrated with c(AgNO3) = 0.01 mol/L (instrument parameters and an example of a curve are given in the appendix).
1 mL c(AgNO3) = 0.01 mol/L corresponds to 0.3545 mg chlorine ppm chlorine = (EP1 - C31) x C01 x C02 x C35 / C00
EP1 = titrant consumption up to the endpoint, in mL C00 = sample weight in g
C01 = 0.3545
C02 = 1000 (for 1 kg)
C35 = titer of AgNO3 solution
C31 = blank value for reagents (in mL AgNO3 solution)
As this is a trace analysis, only chloride-free reagents and ultrapure water should be used. Great care should also be taken that the glassware used is meticulously clean.
– ASTM D 4929-89
Standard Test Methods for Determination of Organic Chloride in Crude Oil
Method parameters & calculation Titration curve Method 18
'pa785 DMP Titrino 02287 785.0010 date 2000-11-22 time 14:28 0 DET U M18
parameters
>titration parameters
meas.pt.density 4 min.incr. 10.0 àl dos.rate max. ml/min signal drift 20 mV/min equilibr.time 38 s start V: OFF pause 0 s meas.input: 1 temperature 25.0 °C
>stop conditions
stop V: abs.
stop V 20 ml stop U OFF mV stop EP 9 filling rate max. ml/min
>statistics
status: OFF
>evaluation
EPC 5 EP recognition: all fix EP1 at U OFF mV pK/HNP: OFF
>preselections
req.ident: id1 req.smpl size: all limit smpl size: OFF activate pulse: OFF ---
'de785 DMP Titrino 02287 785.0010 date 2000-11-22 time 14:28
DET U M18 def>formula
Chlorine=(EP1-C31)*C01*C02*C35/C00 RS1 text Chlorine RS1 decimal places 2 RS1 unit: ppm RS1 limit control: OFF
>silo calculations
match id: OFF
>common variables
>report
report COM1:full;curve;
>mean MN1=RS1
>temporary variables ---
'cf785 DMP Titrino 02287 785.0010 date 2000-11-22 time 14:28
DET U M18 C-fmla
C01 0.3545 C02 1000 ---
Method 18 – Organically bound chlorine in crude oil
Method 19 – Alkalinity of gas absorption solutions containing amines (Jefferson Test Method)
Recommended accessories
General
Definition Reagents
Analysis
Calculations
Remarks
• 6.3014.223 Exchange Unit, 20 mL
• 6.0219.100 combined pH glass electrode with 6.1236.040 SGJ sleeve and 6.2104.020 electrode cable
• 6.1414.010 titration vessel lid and 6.1415.310 titration vessel
• 6.1440.010 gas inlet and overflow tube
In some cases alkaline amine solutions are used for the absorption of acidic gas constituents. These are primarily monoethanolamine (MEA), diglycolamine (DGA) and di-isopropanolamine (DIPA, also called ADIP). The content of the absorption solution is periodically checked to ensure that the absorption behavior remains optimal (e.g. for H2S). If the content drops below a fixed limit, (e.g. 16%) then new amine must be added.
The solutions are titrated with sulfuric acid to pH 4.5 and the content of the particu- lar amine is calculated.
w(amine), that is ôweight %ằ of the particular amine (MEA or DGA or DIPA).
– Titrant: c(H2SO4) = 0.05 mol/L (ô0.1 Nằ): e.g. Merck No. 109985 – Nitrogen: from gas cylinder
– Dist. H2O
– Buffer solutions: pH = 4.0 and pH = 7.0 (Metrohm No. 6.2307.100 and 6.2307.110)
The pH glass electrode is calibrated with buffer solutions pH = 4.0 and pH = 7.0.
Approx. 100 mL dist. H2O is placed in the titration vessel and 2...3 g sample solu- tion is added from a syringe (sample weight obtained by weighing the syringe before and after). In a first SET titration the solution is then titrated with c(H2SO4)
= 0.05 mol/L to pH = 4.5, this gives result A in mL. Nitrogen is now blown through the solution under stirring for 5 min and the solution is again titrated to pH = 4.5 in a second SET titration: result B in mL (instrument parameters in appendix).
w(MEA), or w(DGA) or w(DIPA) = result B x C01 x C02 / C00 C00 = sample weight in g
C01 = 0.1 (= 2 x 0.05; ônormalityằ of H2SO4 in mol/L)
C02 = ôequivalent weightsằ (MEA = 6.1 / DGA = 10.5 / DIPA = 13.3)
– Blowing nitrogen through the solution removes CO2 and any H2S that may be present and the pH increases again. This is best done under a fume hood (H2S not only have an unpleasant smell but is also extremely toxic)!!!
– For small amine contents (e.g. in acidic water, regenerators) 100 mL sample is measured in (no dist. H2O). C00 then becomes approximately = 100 (sample weight in g).
Method parameters & calculation Titration curve Method 19
Method 19 – Alkalinity of gas absorption solutions containing amines (Jefferson Test Method)
'pa785 DMP Titrino 02287 785.0010 date 2000-11-22 time 14:52 0 SET pH M19
parameters
>SET1
EP at pH 4.50 dynamics 5 max.rate 10 ml/min min.rate 25.0 àl/min stop crit: drift stop drift 15 àl/min
>SET2
EP at pH OFF
>titration parameters
titr.direction: - pause 1 0 s start V: OFF pause 2 0 s extr.time 0 s meas.input: 1 temperature 25.0 °C time interval 2 s
>stop conditions
stop V: abs.
stop V 60 ml filling rate max. ml/min
>statistics
status: OFF
>preselections
conditioning: OFF req.ident: id1 req.smpl size: all limit smpl size: OFF activate pulse: OFF ---
'de785 DMP Titrino 02287 785.0010 date 2000-11-22 time 14:52
SET pH M19 def>formula
MEA=EP1*C01*C02/C00
RS1 text MEA RS1 decimal places 2 RS1 unit: % RS1 limit control: OFF
>silo calculations
match id: OFF
>common variables
>report
report COM1:full;curve;
>mean MN1=RS1
>temporary variables ---
'cf785 DMP Titrino 02287 785.0010 date 2000-11-22 time 14:52
SET pH M19 C-fmla
C01 0.1 C02 6.1 ---
Method 20 – Analysis of used alkaline absorption and washing solutions
Recommended accessories
General
Definitions
Reagents
Analysis
• 6.3014.223 Exchange Unit, 20 mL
• 6.0219.100 combined pH glass electrode with 6.2104.020 electrode cable NaOH solutions are used for the absorption of acidic gas constituents or washing out crude oil (e.g. removal of naphthenic acid and mercaptans). The method de- scribes the determination of the total alkalinity, the fractions of strong and weak bases, as well as the fraction of used base by calculation. The following are re- garded as being strong bases: NaOH, Na2CO3, Na2S, Na phenolates (NaOPh) and Na alkylmercaptides (NaSR). The titration is carried out with HCl; the follow- ing reactions take place:
NaOH + HCl → NaCl + H2O Na2CO3 + HCl → NaCl + NaHCO3 + H2O
Na2S + HCl → NaCl + NaHS + H2O NaOPh + HCl → NaCl + HOPh + H2O
NaSR + HCl → NaCl + HSR + H2O
The corresponding titration products are defined as being weak bases: NaHCO3, NaHS as well as Na naphthenates (NaOOCR):
NaHCO3 + HCl → NaCl + H2CO3 (H2O + CO2) + H2O NaHS + HCl → NaCl + H2S + H2O
NaOOCR + HCl → NaCl + HOOCR + H2O
Total alkalinity: 1...3 endpoints can occur. The last EP is always used for the calcu- lation of the total alkalinity.
Strong bases: 1...3 endpoints can occur. EP1 is always used for the calculation of the strong bases.
Weak bases: 1...X endpoints can occur. EP1 (strong bases) is subtracted from the last EP for the calculation.
The total alkalinity as well as the strong and weak bases are given as w(NaOH) (weight %). The fraction of used bases is a useful indication of the condition of the absorption or washing solution. It is calculated as follows:
Fraction of used base (%) = 100 x (total base – strong base) total base
– Titrant: c(HCl) = 0.1 mol/L, e.g. Merck No. 109060 – Solvents: isopropanol and dist. H2O
1...10 g sample is placed in a beaker (see following table). It is treated with 50 mL each of isopropanol and dist. H2O and then titrated with c(HCl) = 0.1 mol/L. If the sample contains mercaptans and sulfides then it is better to work under a fume hood (instrument parameters and an example of a curve are given in the appen- dix).
Method 20 – Analysis of used alkaline absorption and washing solutions
Table for the sample weight
Calculations
Remarks
Literature w(NaOH) expected Sample weight in g
0...2% 10
2...4% 5
4...8% 2
>8% 1
Results are obtained as w(NaOH), ôweight %ằ, RS = result RS 1 = w(total bases) = EPn x C01 x C02 / C00 RS 2 = w(strong bases) = EP1 x C01 x C02 / C00
RS 3 = w(weak bases) = (EPn - EP1) x C01 x C02 / C00 RS 4 = intermediate result = (RS1 - RS2) / RS1
RS 5 = fraction of used bases (%) = C03 x RS4 C00 = Sample weight in g
C01 = 4 (ôequivalent weightằ NaOH) C02 = 0.1 (concentration HCl in mol/L) C0* = 100 (for %)
EPn = last EP (EP2 or EP3)
If H2S and mercaptans are also to be determined in these absorption solutions then Method 12 can be used.
– UOP Method 209-83
Potentiometric Analysis of Used Refinery Caustic Solutions – UOP Method 210-76T
Caustic Solution Analysis – Double Indicator
Method parameters & calculation
Titration curve Method 20
'pa785 DMP Titrino 02287 785.0010
date 2000-11-24 time 08:00 0
DET U M20 parameters >titration parameters meas.pt.density 4
min.incr. 10.0 àl dos.rate max. ml/min signal drift 10 mV/min equilibr.time 52 s start V: OFF pause 0 s meas.input: 1
temperature 25.0 °C >stop conditions stop V: abs. stop V 20 ml stop U OFF mV stop EP 9
filling rate max. ml/min >statistics status: OFF >evaluation EPC 5
EP recognition: all fix EP1 at U OFF mV pK/HNP: OFF >preselections req.ident: id1 req.smpl size: all limit smpl size: OFF activate pulse: OFF --- 'de785 DMP Titrino 02287 785.0010
date 2000-11-24 time 08:00
DET U M20
def>formula TB=EP2*C01*C02/C00 RS1 text TB RS1 decimal places 2
RS1 unit: % RS1 limit control: OFF SB=EP1*C01*C02/C00 RS2 text SB RS2 decimal places 2
RS2 unit: % RS2 limit control: OFF WB=(EP2-EP1)*C01*C02/C00 RS3 text WB RS3 decimal places 2
RS3 unit: % RS3 limit control: OFF RS4=(RS1-RS2)/RS1 RS4 text RS4 decimal places 4
RS4 unit: RS4 limit control: OFF UB=C03*RS4 RS5 text UB RS5 decimal places 2
RS5 unit: % RS5 limit control: OFF >silo calculations match id: OFF >common variables >report report COM1:full;curve; 'cf785 DMP Titrino 02287 785.0010
date 2000-11-24 time 08:00
DET U M20 C-fmla C01 4
C02 0.1 C03 100 ---
Method 20 – Analysis of used alkaline absorption and washing solutions
• 6.3014.153 Exchange Unit, 5 mL, or 6.3014.213, 10 mL, or 6.3014.223, 20 mL
• Spectrode 610 nm, 6.5501.01X or
6.0502.140 Cu ISE and 6.0726.107 Ag/AgCl reference electrode or
6.0504.100 Ca ISE and 6.0726.107 Ag/AgCl reference electrode
• 6.2104.020 electrode cable (ISE) and 6.2106.020 (reference electrode) Ethylenediaminetetraacetic acid (EDTA) forms 1:1 complexes of different strength with many metal ions. The stability of the complexes depends very much on the pH. The most frequently performed determinations (water hardness, Ca, Mg, Zn) are carried out in alkaline buffered solutions. As EDTA is insoluble in water the disodium salt dihydrate (Na2EDTA x 2 H2O) is used.
Reaction mechanism:
(Na2EDTA = H2Y2– / Me2+ e.g.. Ca2+ , Me3+ z.B. Al3+) Me2+ + H2Y2– → MeY2– + 2 H+
Me3+ + H2Y2– → MeY– + 2 H+
All complexes contain metal and complexing agent in the ratio 1:1, independent of the charge of the metal ion. As hydrogen ions (H+) are formed, work must be carried out in buffered solutions. In the direct determinations described here the total content of the complex-forming metal ions present is obtained. Separation is not normally possible.
So-called primary titrimetric standards are used for the titer determination. The content of these hardly changes, they are available with a defined degree of purity, can be dried and are directly traceable to standard reference materials (e.g. from NIST = National Institute of Standards and Technology, USA). Such a recom- mended primary titrimetric standard or secondary standard for EDTA is e.g.:
Merck No. 102 059, CaCO3 ôSuprapurằ, M = 100.09 g/mol
Three different indication methods are described under ôTiter determinationsằ.
Titrant, HCl, Ca standard and buffer solution are identical. Two additional auxiliary solutions may also be needed.
Initial titrant substance: Na2EDTA x 2 H2O, e.g. Merck No. 108418 (Titriplex III).
– Titrants
c(Na2EDTA) = 0.1 mol/L: 37.3 g Na2EDTA x 2 H2O is dissolved in dist. H2O, treated with 10 mL c(NaOH) = 1 mol/L and made up to 1 liter with dist. H2O.
c(Na2EDTA) = 0.05 mol/L: 18.65 g Na2EDTA x 2 H2O is dissolved in dist. H2O, treated with 10 mL c(NaOH) = 1 mol/L and made up to 1 liter with dist. H2O.
c(Na2EDTA) = 0.025 mol/L: 9.33 g Na2EDTA x 2 H2O is dissolved in dist. H2O,
Method 21 – Titer determination of EDTA solutions
Recommended accessories
General
Na2EDTA
Reagents
Method 21 – Titer determination of EDTA solutions
Titer determinations – Buffer solution pH = 10
54 g NH4Cl is dissolved in dist. H2O, treated with 350 mL w(NH3) = 25% and made up to 1 liter with dist. H2O.
– Color indicator Eriochrome black T
0.1 g Eriochrome black T and approx. 0.2 g ascorbic acid (vitamin C) are dis- solved in dist. H2O and then made up to 100 mL.
– Cu-complexing solution
e.g. c[Cu(NH4)2EDTA] = 0.1 mol/L; Merck No. 105217 – Ca primary titrimetric standard
CaCO3 ôSuprapurằ, Merck No. 102059 – Hydrochloric acid
w(HCl) = 30...35%, analytical grade