CN108982748A - In a kind of measurement ethylene cracker in mixed ammonium/alkali solutions mixed base method - Google Patents
In a kind of measurement ethylene cracker in mixed ammonium/alkali solutions mixed base method Download PDFInfo
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Abstract
The present invention relates to titration detection fields, disclose a kind of method for measuring mixed base in mixed ammonium/alkali solutions in ethylene cracker, method includes the following steps: (1) takes a mixed ammonium/alkali solutions sample, the mixed ammonium/alkali solutions sample is titrated with sulfuric acid, when pH is 8-8.2, stop titration；(2) formaldehyde is added in the solution a obtained to step (1), reacts 15-30 seconds；(3) stop titration when pH is 8-8.2 with the solution b obtained after sulfuric acid titration step (2) reaction；(4) continue the solution c that titration step (3) obtain with sulfuric acid, when pH is 4.1-4.3, stop titration.This method operating process is simple, and generates without precipitating, and can be applied in automatical potentiometric titrimeter.
Description
Technical field
The present invention relates to titration detection fields, and in particular, in a kind of measurement ethylene cracker in mixed ammonium/alkali solutions
The method of mixed base.
Background technique
The main component of mixed base is NaOH, Na in ethylene cracker2CO3And Na2S, production process need to monitor each group
Divide the concentration of alkali, the concentration analysis of NaOH, extremely important especially in lye.
Classical ethylene cracker mixed base concentration analysis is using manual volumetric precipitation method, and analytic process uses
Two kinds of reagents are added in two parts of sample solutions, titration process, and totally three steps titrate, and the specific method is as follows: a sample solution A, is taken, to
Phenolphthalein reagent is added in sample, then with sulfuric acid titration until solution is become colorless by aubergine；B, to the colourless solution of formation
Middle addition formaldehyde simultaneously reacts, and colourless solution becomes purplish red solution after reaction, is then continued to titrate the purplish red solution with sulfuric acid,
Until solution becomes colourless；C, another sample is taken, BaCl is added2, completely after precipitating, phenolphthalein is added, is titrated with sulfuric acid, until
Solution is become colorless by aubergine.The reaction mechanism is as follows for this method:
A:NaOH+H2SO4→Na2SO4+H2O
Na2CO3+H2SO4→Na2SO4+NaHCO3
Na2S+H2SO4→Na2SO4+NaHS
B:NaHS+HCHO → NaOH+CH2S
NaOH+H2SO4→Na2SO4+H2O
C:Na2CO3+BaCl2→Ba2CO3↓+NaCl
NaOH+H2SO4→Na2SO4+H2O
Na2S+H2SO4→Na2SO4+NaHS
This method operating process is relatively complicated, and there is more difficult judgements of titration end-point after low efficiency, generation precipitating etc. to lack
Point, also, the process that formaldehyde is added easily causes damages to human health, pollutes to analysis environment.It is dripped using automatic current potential
Pollution of the formaldehyde to human body and environment can effectively be avoided by automatic ration liquid feeding by determining instrument analysis mixed base, still, due to upper
It is more to state titration process generation precipitating, is easy to interfere electrode, influences measurement result, and precipitate and easily cause blocking liquid outlet.
Summary of the invention
The purpose of the present invention is overcome to mix using in mixed ammonium/alkali solutions in measurement ethylene cracker in the prior art
The method complexity of alkali, defect that is inaccurate and can not be applied to automatical potentiometric titrimeter, provide a kind of measurement ethylene cracker
The method of mixed base in middle mixed ammonium/alkali solutions.
To achieve the goals above, the present invention provides in a kind of measurement ethylene cracker mixed base in mixed ammonium/alkali solutions
Method, wherein method includes the following steps:
(1) a mixed ammonium/alkali solutions sample is taken, titrates the mixed ammonium/alkali solutions sample with sulfuric acid, when pH is 8-8.2, is stopped
Only titrate；
(2) formaldehyde is added in the solution a obtained to step (1), reacts 15-30 seconds；
(3) stop titration when pH is 8-8.2 with the solution b obtained after sulfuric acid titration step (2) reaction；
(4) continue the solution c that titration step (3) obtain with sulfuric acid, when pH is 4.1-4.3, stop titration.
The method of the invention has the advantage that
(1) it only needs to use a mixed ammonium/alkali solutions sample, operating process is simple；
(2) this method does not precipitate generation, when being applied in automatical potentiometric titrimeter, effectively avoids precipitating to automatic current potential
The electrode of titrator generates interference or causes to block liquid outlet.
Other features and advantages of the present invention will the following detailed description will be given in the detailed implementation section.
Specific embodiment
Detailed description of the preferred embodiments below.It should be understood that described herein specific
Embodiment is merely to illustrate and explain the present invention, and is not intended to restrict the invention.
The endpoint of disclosed range and any value are not limited to the accurate range or value herein, these ranges or
Value should be understood as comprising the value close to these ranges or value.For numberical range, between the endpoint value of each range, respectively
It can be combined with each other between the endpoint value of a range and individual point value, and individually between point value and obtain one or more
New numberical range, these numberical ranges should be considered as specific open herein.
The present invention provides it is a kind of measurement ethylene cracker in mixed ammonium/alkali solutions method, wherein this method include with
Lower step:
(1) a mixed ammonium/alkali solutions sample is taken, titrates the mixed ammonium/alkali solutions sample with sulfuric acid, when pH is 8-8.2, is stopped
Only titrate；
(2) formaldehyde is added in the solution a obtained to step (1), reacts 15-30 seconds；
(3) stop titration when pH is 8-8.2 with the solution b obtained after sulfuric acid titration step (2) reaction；
(4) continue the solution c that titration step (3) obtain with sulfuric acid, when pH is 4.1-4.3, stop titration.
In the present invention, the mixed ammonium/alkali solutions are the mixed ammonium/alkali solutions in ethylene cracker, the usual mixing alkali soluble
Contain NaOH, Na in liquid2CO3And Na2S。
Measuring method of the present invention corresponds to following principle:
(1)NaOH+H2SO4→Na2SO4+H2O
Na2CO3+H2SO4→Na2SO4+NaHCO3
Na2S+H2SO4→Na2SO4+NaHS
(2)NaHS+HCHO→NaOH+CH2S
(3)NaOH+H2SO4→Na2SO4+H2O
(4)NaHCO3+H2SO4→Na2SO4+H2O+CO2
According to above-mentioned principle, NaOH, Na in the mixed ammonium/alkali solutions2CO3And Na2The content of S can be calculate by the following formula:
Na2CO3Mass fraction=212V3C/m × 100%；
Na2Mass fraction=156V of S2C/m × 100%；
The mass fraction of NaOH=80c (V1- V2- V3)/m × 100%；
Wherein, c is the concentration of sulfuric acid, mol/L；M is that the weight of mixed ammonium/alkali solutions sample (can be surveyed by electronic balance
Amount), g；V1For the volume of the sulfuric acid of step (1) consumption, L；V2For the volume of the sulfuric acid of step (3) consumption, L；V3For step (4)
The volume of the sulfuric acid of consumption, L.
There is no particular limitation for concentration of the present invention to the sulfuric acid, can be sulfuric acid concentration commonly used in the art, preferably
In the case of, in step (1), (3) and (4), the concentration of sulfuric acid used is identical, and is 0.04-0.06mol/L.
In the present invention, in order to improve the accuracy of titration results, under preferable case, in step (1) and (3), sulfuric acid is used
The condition of titration includes: that titration temperature is 10-35 DEG C, rate of titration 9-12mL/min；In step (4), titrated with sulfuric acid
Condition include: titration temperature be 10-35 DEG C, rate of titration 8-10mL/min.
In the present invention, to the concentration of the formaldehyde in step (2), there is no particular limitation, can be the conventional choosing of this field
It selects, such as the concentration of formaldehyde can be 10-20 weight %.
In the present invention, the dosage of the formaldehyde in step (2) reacts away the NaHS generated in step (1) completely,
For example, the dosage of formaldehyde can be 10-15mL.
When the method for the invention is applied to automatical potentiometric titrimeter, generated in this method without precipitating, it can be effective
It avoids precipitating and interference is generated to the electrode of automatical potentiometric titrimeter or causes to block liquid outlet；And only need a mixing alkali soluble
Liquid sample, method are simple.The automatical potentiometric titrimeter can be the conventional selection of this field, such as can be logical for ten thousand
809Titrando automatical potentiometric titrimeter.
When the method for the invention is applied to manual operation, titration end-point can be indicated with acid-base indicator, for example,
In step (1) and (3), the pH value of titration end-point can be measured by phenolphthalein indicator.Concrete operations are as follows: drip sulphur in step (1)
Phenolphthalein indicator 0.08-0.13mL is added in the forward direction solution of acid, solution becomes aubergine, phenolphthalein indicator directing terminal at this time
Solution is shown as to be become colorless by aubergine.
In step (4), the pH value of titration end-point can be measured by methyl orange indicator.Concrete operations are as follows: in drop sulfuric acid
Forward direction solution in be added methyl orange indicator 0.13-0.17mL, solution turns yellow at this time, methyl orange indicator directing terminal
Being shown as solution becomes orange red from yellow.
In the present invention, if Prediction and Acquisition come mixed ammonium/alkali solutions in mixed base excessive concentration, in order to increase titration survey
Fixed accuracy under preferable case, will detect again after the mixed ammonium/alkali solutions dilution that acquisition comes, and mix alkali soluble calculating at this time
It will be multiplied by corresponding extension rate when the content of the mixed base in liquid.
The present invention will be described in detail by way of examples below.In following embodiment, the concentration of sulfuric acid is
0.05mol/L；
Automatical potentiometric titrimeter is ten thousand logical 809Titrando automatical potentiometric titrimeters, using 869 autosamplers；
Mixed ammonium/alkali solutions sample 1 comes from China petroleum Chemicals Co., Ltd. Town Hai Lian Hua branched Corporation ethylene cracker
Middle separative unit alkali washing process lower part lye；
Mixed ammonium/alkali solutions sample 2 comes from China petroleum Chemicals Co., Ltd. Town Hai Lian Hua branched Corporation ethylene cracker
Middle Dry gas treatment unit alkali washing process；
Mixed ammonium/alkali solutions sample 3 comes from China petroleum Chemicals Co., Ltd. Town Hai Lian Hua branched Corporation ethylene cracker
Lye in the middle part of middle separative unit alkali washing process.
Embodiment 1
1, automatic potential titrator tests are fixed:
(1) 10mL mixed ammonium/alkali solutions sample 1 is taken, dilutes 25 times of volumes with distilled water, the mixing alkali soluble after taking 10mL to dilute
50mL distilled water is added in liquid sample, titrates (titration temperature is 23 DEG C, the rate of titration 12mL/min) solution with sulfuric acid, when
When pH is 8.2, stop titration；
(2) formaldehyde 10mL (concentration is 13 weight %) is added in the solution a obtained to step (1), reacts 20 seconds；
(3) molten with being obtained after sulfuric acid titration (titration temperature is 23 DEG C, rate of titration 12mL/min) step (2) reaction
Liquid b stops titration when pH is 8.2；
(4) continue the solution that titration (titration temperature is 23 DEG C, rate of titration 10mL/min) step (3) obtains with sulfuric acid
C stops titration when pH is 4.2.
2, it is manually operated:
(1) 10mL mixed ammonium/alkali solutions sample 1 is taken, dilutes 25 times of volumes with distilled water, the mixing alkali soluble after taking 10mL to dilute
50mL distilled water is added in liquid sample, and phenolphthalein indicator 0.1mL is added, and with sulfuric acid titration, (titration temperature is 23 DEG C, rate of titration
Stop titration when the mixed ammonium/alkali solutions sample is become colorless by aubergine for the 12mL/min) solution；
(2) formaldehyde 10mL (concentration is 13 weight %) is added in the solution a obtained to step (1), reacts 20 seconds；
(3) molten with being obtained after sulfuric acid titration (titration temperature is 23 DEG C, rate of titration 12mL/min) step (2) reaction
Liquid b stops titration when solution is become colorless by aubergine；
(4) methyl orange indicator 0.13mL is added in the solution c obtained to step (3), continues titration (titration temperature with sulfuric acid
Degree is 23 DEG C, rate of titration 10mL/min), when solution becomes orange red from yellow, stop titration.
Above-mentioned automatical potentiometric titrimeter and manually operated measurement result are as shown in table 1.
Embodiment 2
1, automatic potential titrator tests are fixed:
(1) 10mL mixed ammonium/alkali solutions sample 2 is taken, dilutes 25 times of volumes with distilled water, the mixing alkali soluble after taking 10mL to dilute
50mL distilled water is added in liquid sample, with sulfuric acid titration (titration temperature is 35 DEG C, the rate of titration 9mL/min) solution, works as pH
When being 8.1, stop titration；
(2) formaldehyde 12mL (concentration is 20 weight %) is added in the solution a obtained to step (1), reacts 30 seconds；
(3) molten with being obtained after sulfuric acid titration (titration temperature is 35 DEG C, rate of titration 9mL/min) step (2) reaction
Liquid b stops titration when pH is 8.1；
(4) continue the solution that titration (titration temperature is 35 DEG C, rate of titration 8mL/min) step (3) obtains with sulfuric acid
C stops titration when pH is 4.1.
2, it is manually operated:
(1) 10mL mixed ammonium/alkali solutions sample 2 is taken, dilutes 25 times of volumes with distilled water, the mixing alkali soluble after taking 10mL to dilute
50mL distilled water is added in liquid sample, and phenolphthalein indicator 0.13mL is added, and with sulfuric acid titration, (titration temperature is 23 DEG C, rate of titration
Stop titration when the mixed ammonium/alkali solutions sample is become colorless by aubergine for the 9mL/min) solution；
(2) formaldehyde 12mL (concentration is 20 weight %) is added in the solution a obtained to step (1), reacts 30 seconds；
(3) stop drop when solution is become colorless by aubergine with the solution b obtained after sulfuric acid titration step (2) reaction
It is fixed；
(4) methyl orange indicator 0.17mL is added in the solution c obtained to step (3), continues titration (titration temperature with sulfuric acid
Degree is 35 DEG C, rate of titration 8mL/min), when solution becomes orange red from yellow, stop titration.
Above-mentioned automatical potentiometric titrimeter and manually operated measurement result are as shown in table 1.
Embodiment 3
1, automatic potential titrator tests are fixed:
(1) 10mL mixed ammonium/alkali solutions sample 3 is taken, dilutes 25 times of volumes with distilled water, the mixing alkali soluble after taking 10mL to dilute
50mL distilled water is added in liquid sample, with sulfuric acid titration (titration temperature is 10 DEG C, rate of titration 10mL/min) mixed ammonium/alkali solutions
Sample stops titration when pH is 8；
(2) formaldehyde 10mL (concentration is 10 weight %) is added in the solution a obtained to step (1), reacts 15 seconds；
(3) molten with being obtained after sulfuric acid titration (titration temperature is 10 DEG C, rate of titration 10mL/min) step (2) reaction
Liquid b stops titration when pH is 8.0；
(4) continue the solution that titration (titration temperature is 10 DEG C, rate of titration 9mL/min) step (3) obtains with sulfuric acid
C stops titration when pH is 4.3.
2, it is manually operated:
(1) 10mL mixed ammonium/alkali solutions sample 3 is taken, dilutes 25 times of volumes with distilled water, the mixing alkali soluble after taking 10mL to dilute
50mL distilled water is added in liquid sample, and phenolphthalein indicator 0.08mL is added, and with sulfuric acid titration, (titration temperature is 10 DEG C, rate of titration
Stop titration when the mixed ammonium/alkali solutions sample is become colorless by aubergine for the 10mL/min) solution；
(2) formaldehyde 10mL (concentration is 10 weight %) is added in the solution a obtained to step (1), reacts 15 seconds；
(3) molten with being obtained after sulfuric acid titration (titration temperature is 10 DEG C, rate of titration 10mL/min) step (2) reaction
Liquid b stops titration when solution is become colorless by aubergine；
(4) methyl orange indicator 0.15mL is added in the solution c obtained to step (3), continues titration (titration temperature with sulfuric acid
Degree is 10 DEG C, rate of titration 9mL/min), when solution becomes orange red from yellow, stop titration.
Above-mentioned automatical potentiometric titrimeter and manually operated measurement result are as shown in table 1.
Table 1
The method of the invention can both be dripped with manual operation or with automatic current potential it can be seen from the result of table 1
Determine instrument operation, also, error very little very close with the result of automatical potentiometric titrimeter operation is manually operated.
The preferred embodiment of the present invention has been described above in detail, still, during present invention is not limited to the embodiments described above
Detail within the scope of the technical concept of the present invention can be with various simple variants of the technical solution of the present invention are made, this
A little simple variants all belong to the scope of protection of the present invention.
It is further to note that specific technical features described in the above specific embodiments, in not lance
In the case where shield, can be combined in any appropriate way, in order to avoid unnecessary repetition, the present invention to it is various can
No further explanation will be given for the combination of energy.
In addition, various embodiments of the present invention can be combined randomly, as long as it is without prejudice to originally
The thought of invention, it should also be regarded as the disclosure of the present invention.
Claims (8)
1. a kind of method of mixed base in measurement ethylene cracker mixed ammonium/alkali solutions, which is characterized in that this method includes following
Step:
(1) a mixed ammonium/alkali solutions sample is taken, titrates the mixed ammonium/alkali solutions sample with sulfuric acid, when pH is 8-8.2, stops drop
It is fixed；
(2) formaldehyde is added in the solution a obtained to step (1), reacts 15-30 seconds；
(3) stop titration when pH is 8-8.2 with the solution b obtained after sulfuric acid titration step (2) reaction；
(4) continue the solution c that titration step (3) obtain with sulfuric acid, when pH is 4.1-4.3, stop titration.
2. measuring method according to claim 1, wherein in step (1), (3) and (4), the concentration phase of sulfuric acid used
It together, and is 0.04-0.06mol/L.
3. measuring method according to claim 1 or 2, wherein in step (1) and (3), with the condition packet of sulfuric acid titration
Include: titration temperature is 10-35 DEG C, rate of titration 9-12mL/min；It include: drop with the condition that sulfuric acid titrates in step (4)
Determining temperature is 10-35 DEG C, rate of titration 8-10mL/min.
4. measuring method according to claim 1 or 2, wherein in step (2), the concentration of formaldehyde is 10-20 weight %.
5. measuring method according to claim 1 or 2, wherein in step (2), the dosage of formaldehyde is 10-15mL.
6. measuring method according to claim 1 or 2, wherein in step (1) and (3), the pH value of titration end-point passes through phenol
Phthalein indicator measurement.
7. measuring method according to claim 1 or 2, wherein in step (4), the pH value of titration end-point passes through methyl orange
Indicator measurement.
8. measuring method according to claim 1 or 2, wherein contain NaOH, Na in the mixed ammonium/alkali solutions sample2CO3
And Na2S。
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| CN109828082A (en) * | 2019-02-25 | 2019-05-31 | 山东京博石油化工有限公司 | A kind of quantitative detecting method of desulfurization alcoholic lye neutral and alkali ingredient |
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| CN102043003A (en) * | 2010-12-03 | 2011-05-04 | 江南大学 | Method for measuring mixed base concentration by combining pH electrode and flow injection analysis (FIA) |
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