CN100395546C - Measurement of element sulfur content in distillate by oscilloscopic polarography - Google Patents
Measurement of element sulfur content in distillate by oscilloscopic polarography Download PDFInfo
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- CN100395546C CN100395546C CNB2005100025940A CN200510002594A CN100395546C CN 100395546 C CN100395546 C CN 100395546C CN B2005100025940 A CNB2005100025940 A CN B2005100025940A CN 200510002594 A CN200510002594 A CN 200510002594A CN 100395546 C CN100395546 C CN 100395546C
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Abstract
The present invention relates to a method for measuring element sulfur content in oil distillate by an oscilloscopic polarography, which comprises the following steps: triphenyl phosphorus is added to a sample to react with element sulfur to generate triphenylphosphine sulfide; standard solutions with different element sulfur contents are prepared; polarographic wave crest electric current values produced by the triphenylphosphine sulfide in the standard solutions are related to the element sulfur contents to establish standard curves; then, the element sulfur content in the sample is obtained by the polarographic wave crest electric current values produced by a tested sample through the standard curves. The method with simple instrumentation and convenient operation almost overcomes the interference of thioether, thiol and disulfide existing in the sample to the measuring result of the elemental sulfur content.
Description
Technical field
The present invention is the assay method of element sulfur content in a kind of distillate, specifically, is a kind of method with element sulfur content in the oscillopolarographic detection distillate.
Background technology
The elementary sulfur that exists in oil and products thereof not only influences oil quality, and oil refining apparatus, plant equipment and storage and handling facility are produced corrosion.So the method for elementary sulfur has crucial meaning in a kind of express-analysis petroleum fraction of exploitation and the petroleum products.
The method that is used for analytical element sulphur is more, as spectrophotometric method, colourimetry, gravimetric method etc.And these methods are difficult to the analysis of complex materials such as hydro carbons usually.The interference of other form sulphur has hindered analysis to elementary sulfur in the sample in many cases.Polarography is to utilize measured matter oxidation on electrode to carry out substance quantitative analysis with the dissufion current that reduction produces, and equipment needed thereby is simple.General employing of past classical direct current polarography is measured the elementary sulfur in crude oil fractions and the petroleum products.But because low, the poor anti jamming capability of sensitivity of classical direct current polarography, and the smell and the toxicity of the methyl alcohol-pyridine-hydrochloric acid medium that adopts are bigger, and methyl alcohol is relatively poor to the dissolubility of crude oil and higher cut simultaneously, and therefore this method can not satisfy the real work needs.
Wu Mei etc. are at " DETERMINATION OF ELEMENTAL SULFUR IN in petroleum fraction and the product " (petroleum refining and chemical industry, 2000,31 (1): 58) adopt the potpourri of methyl alcohol, toluene, acetic acid and ammonium acetate buffer solution in the literary composition as supporting electrolyte analytical element sulphur, compare with classical direct current polarography, it has advantages such as highly sensitive, that resolution is strong, analysis speed is fast.Therefore but the range of linearity of this method is narrower, when element sulfur content is lower than 4 μ g/ml, turning point occurs about 2 μ g/ml places greatly, can not detection level be lower than the elementary sulfur of 0.1 μ g/ml, and its testing result is subjected to the interference of disulfide.
CN1338630A and CN1338631A adopt oscilloscopic polarography that crude oil and petroleum fraction and petroleum products are measured respectively, and the mixed liquor that adopts sulfuric acid, methyl alcohol and toluene is the element sulfur content in the supporting electrolyte working sample.The polarogram peak current that elementary sulfur produces in the direct working sample of this method, and be associated with the sample element sulfur content in view of the above, typical curve set up.The mercaptan that exists in the sample during mensuration, thioether, disulfide sulfides exert an influence to the accuracy of testing result, and when disulfide content in the sample surpasses 10 μ g/ml, peak current will increase gradually; When mercaptans content reached 100 μ g/ml or thioether content and surpasses 300 μ g/ml, peak current began to reduce, and the range of linearity is narrow, is 0～4 μ g/ml.
Cao Fengxian is at " (elementary sulfur in the gas chromatography determination catalytically cracked gasoline " (petroleum refining and chemical industry, 2004,35 (3): 69) earlier the elementary sulfur in the catalytically cracked gasoline is transformed into triphenylphosphine sulfide in the literary composition, carry out quantitative test with the gas chromatography of flame photometric detector (FPD) (FPD) that has the phosphorus optical filter then, solved the problem that elementary sulfur boiling point height can't the chromatograph method be analyzed.But this method only limits to the analysis of catalytically cracked gasoline, and the gas chromatography cost of using is higher.
Summary of the invention
The purpose of this invention is to provide a kind of method of utilizing oscillographic polarography to measure element sulfur content in the distillate, this method is simple to operate, analysis time short, and measurement result is accurate.
The method of element sulfur content comprises the steps: in the oscillopolarographic detection distillate provided by the invention
(1) sets up typical curve: elementary sulfur and triphenyl phosphorus adding toluene are mixed with solution, making wherein, element sulfur content is 40～60 mcg/ml, the content of triphenyl phosphorus is 0.1～5.0 mg/ml, make elementary sulfur and triphenyl phosphorus in the solution fully react generation triphenylphosphine sulfide then, make storage liquid, storage liquid is become the standard solution of a series of different element sulfur contents with dilution with toluene, after getting a certain amount of standard solution and being diluted to certain volume with supporting electrolyte, polarogram peak point current with triphenylphosphine sulfide generation in the oscillopolarographic detection standard solution, the polarogram peak point current that triphenylphosphine sulfide in the standard solution of different element sulfur contents is produced is associated with the element sulfur content of solution and sets up typical curve
(2) element sulfur content of mensuration distillate sample: distillate sample and triphenyl phosphorus adding toluene are mixed with solution, the content that makes triphenyl phosphorus is 0.1～5.0 mg/ml, make elementary sulfur and triphenyl phosphorus in the solution fully react generation triphenylphosphine sulfide, press the measuring method of standard solution and measure the polarogram peak point current that triphenylphosphine sulfide produces in the distillate sample, draw element sulfur content corresponding to this peak point current by typical curve.
The inventive method adds triphenyl phosphorus in containing the specimen of elementary sulfur, make it to generate triphenylphosphine sulfide with elementary sulfur reaction back, by measuring the polarogram peak current of triphenylphosphine sulfide, determine the element sulfur content in the sample, thereby can effectively get rid of other sulphur compound in the sample, mercaptan, thioether, disulfide are to the interference of measurement result, the content of elementary sulfur in the accurate working sample is for distillate production, processing unit (plant) and transportation equipment prevent that effectively sulfur corrosion from providing reference data.
Description of drawings
Fig. 1 is the oscillographic polarography first order derivative curve map of the standard solution of the present invention's preparation.
Fig. 2 is the oscillographic polarography peak point current of the inventive method mensuration and the linear dependence figure of element sulfur content.
Embodiment
The inventive method adds excessive triphenyl phosphorus compound in the distillate sample, elementary sulfur in itself and the sample is fully reacted generate triphenylphosphine sulfide, again the element sulfur content of the oscillographic polarography peak point current calculation sample that is produced by triphenylphosphine sulfide.
In toluene solution, elementary sulfur can carry out quick and quantitative reaction with triphenyl phosphorus (TPP), generates triphenyl phasphine sulfide (TPPS):
8(C
6H
5)
3P+S
8→8(C
6H
5)
3P＝S
Triphenyl phasphine sulfide produces polarogram in certain supporting electrolyte, can draw the content of elementary sulfur by the polarogram peak current.
In the described method, when preparation storage liquid or preparation sample, in the sample of sulfur-bearing, add an amount of triphenyl phosphorus earlier, add preferred 0.5～2.0 mg/ml of amount of triphenyl phosphorus.Elementary sulfur and triphenyl phosphorus are fully reacted so that elementary sulfur all changes into triphenyl phasphine sulfide, the suitable temperature of reaction of elementary sulfur and triphenyl phosphorus is 20～60 ℃, and preferred 30～40 ℃, the reaction time is 20～50 minutes, preferred 20～30 minutes.The triphenyl phosphorus that adds in sample crosses that I haven't seen you for ages makes reaction not exclusively, causes triphenylphosphine sulfide peak current to reduce, and produces the peak current of elementary sulfur and influence measurement result.
The compound method of preparing standard solution is in the inventive method: addition element sulphur and triphenyl phosphorus in toluene, make wherein elementary sulfur and triphenyl phosphorus fully react generation triphenylphosphine sulfide, the concentration of the triphenylphosphine sulfide solution that obtains after the reaction is still represented with element sulfur content, solution after the above-mentioned reaction is mixed with the solution of the triphenylphosphine sulfide of different element sulfur contents with toluene, is standard solution.Because the amount of the triphenyl phasphine sulfide that contains in the standard solution is directly proportional with its polarogram peak point current, therefore, the polarogram peak point current of triphenylphosphine sulfide can be associated with element sulfur content in the standard solution, set up typical curve, be used for the mensuration of distillate sample element sulfur content.
After setting up typical curve, when measuring the sulfur-bearing sample, should in sample, add triphenyl phosphorus by the method for preparing standard solution, itself and elementary sulfur are fully reacted, then with the identical condition of titer under triphenylphosphine sulfide produces in the specimen polarogram peak point current, and then obtain the element sulfur content of sample by typical curve.
Supporting electrolyte can adopt conventional electrolytic solution in the inventive method, and preferred supporting electrolyte is made up of toluene, methyl alcohol and sulfuric acid, and wherein the volume ratio of toluene and methyl alcohol is 1: 1, and sulfuric acid content is 0.05～0.3 mol.
When the inventive method is carried out oscillographic polarography mensuration, earlier with the sample electrolyte dilution, be that contrast electrode, platinum electrode are that auxiliary electrode, a mercury are indicator electrode then with the saturated calomel electrode, when initial scanning current potential is-0.1 volt, scan the polarogram that the record measured matter produces.
The inventive method can be under the sulfide content condition with higher the accurate content of elementary sulfur in the working sample, the content that the mercaptan in the sample, thioether and disulfide allow can reach 1～3000 μ g/ml.
The suitable distillate of measuring with the inventive method is any distillate in gasoline, kerosene and the diesel oil distillate, the gasoline that produces as straight-run gasoline, virgin kerosene, straight-run diesel oil, wide petroleum fraction, vacuum gas oil, various secondary processing process, kerosene, diesel oil distillate etc.
Element sulfur content is 0.01～40 mcg/ml in the suitable distillate of measuring, preferred 1～25 mcg/ml.
Below by example in detail the present invention, but the present invention is not limited to this.
Use the JP-3 of Chengdu Instruement Factory type oscillographic polarograph, in the example, three-electrode system.
Supporting electrolyte preparation: add a certain amount of sulfuric acid in volume ratio is 1: 1 toluene, methyl alcohol mixed solution, making sulfuric acid concentration is 0.12mol/L.
The preparation of elementary sulfur storage solutions: get sublimed sulfur 0.0050g, triphenyl phosphorus 0.20g in the 100ml volumetric flask, then with dilution with toluene to scale, 40 ℃ of stirring reactions 20 minutes are mixed with the storage solutions that element sulfur content is 50 μ g/ml.
Example 1
Set up the typical curve of polarogram peak current of the present invention and element sulfur content.
Get an amount of elementary sulfur storage solutions, be made into the standard solution that element sulfur content is 0.1,0.5,1.0,2.0,4.0,8.0,10.0,20.0,30.0,40.0 μ g/ml with toluene respectively.
Get the standard solution of 1ml preparation, be diluted to 10ml with supporting electrolyte, again dilute solution is changed in the electrolysis cup of 10ml, with the saturated calomel electrode is that contrast electrode, platinum electrode are that auxiliary electrode, a mercury are indicator electrode, begin scanning at take-off potential-0.10V place, the first order derivative curve of the voltage-to-current that triphenylphosphine sulfide produces in the record standard solution as shown in Figure 1, and measure peak point current, the i.e. current value at top.
The oscillographic polarography peak point current of triphenylphosphine sulfide in the standard solution of different element sulfur contents is associated with element sulfur content, sets up typical curve.The result shows that in the scope of 0～40 μ g/ml, the concentration of elementary sulfur and polarogram peak point current have the better linearity relation, and its linearly dependent coefficient is 0.9985, as shown in Figure 2.As can be seen from Figure 2, when elementary sulfur concentration during, tangible peak current is arranged also at 0.01 μ g/ml.
Example 2
Investigate the precision and the accuracy of the element sulfur content of the inventive method working sample.
Get an amount of elementary sulfur storage solutions, be mixed with the sample solution that element sulfur content is 1.0,5.0,10.0,25.0 μ g/ml with toluene respectively.The sample solution of getting the 1ml preparation is diluted to 10ml with supporting electrolyte, again dilute solution is changed in the electrolysis cup of 10ml, by the method for example 1 sample solution of different element sulfur contents being carried out oscillographic polarography measures, each sample determination 6 times, the peak point current that is produced by its triphenylphosphine sulfide obtains the element sulfur content of sample by typical curve, the results are shown in Table 1.
As shown in Table 1, better for the sample determination result of element sulfur content in 1～25 μ g/ml repeatability, relative standard deviation is in 3%, and the recovery illustrates that precision of the inventive method and accuracy are better between 99.4～101.2%.The described recovery is the number percent of measured value and theoretical value, down together.
Example 3
Other sulphur compound of this case expedition is to the influence of measurement result of the present invention.
Get an amount of elementary sulfur storage solutions, be mixed with the sample solution that element sulfur content is 10.0,12.0 μ g/ml with toluene respectively.Get the 1ml sample solution, add dimethyl disulphide, mercaptan and thioether respectively, and the sulfur compound concentration that makes adding is 2000 μ g/ml, be diluted to 10ml with supporting electrolyte again, dilute solution is changed in the electrolysis cup of 10ml again, by the method for example 1 sample solution that adds different sulphur compounds is carried out oscillographic polarography and measure, every kind of sample solution is measured 5 times, the peak point current that is produced by its triphenylphosphine sulfide obtains the element sulfur content of sample by typical curve, the results are shown in Table 2.
As shown in Table 2, the existence of dimethyl disulphide, mercaptan and thioether does not influence the measurement result of the inventive method element sulfur content.
Example 4
The accuracy of distillate element sulfur content is measured in investigation with the inventive method.
Get 10ml distillate sample, add the 0.20g triphenyl phosphorus, solution with toluene preparation 100ml, 40 ℃ of stirring reactions 20 minutes are got this solution 1ml, are diluted to 10ml with supporting electrolyte, again dilute solution is changed in the electrolysis cup of 10ml, measure the oscillographic polarography peak point current that its triphenylphosphine sulfide produces by the method for example 1, try to achieve the element sulfur content of distillate sample, the results are shown in Table 3 by typical curve.
The sublimed sulfur that adds 1 milligram in above-mentioned 10ml distillate adds triphenyl phosphorus 0.20g again, then with dilution with toluene to 100ml, the content that makes addition element sulphur in this solution is 10 μ gml
-1, 40 ℃ of stirring reactions 20 minutes.Get the solution after 1ml adds sulphur, be diluted to 10ml with supporting electrolyte, again dilute solution changed in the electrolysis cup of 10ml, measure the oscillographic polarography peak point current that its triphenylphosphine sulfide produces by the method for example 1, try to achieve the element sulfur content of distillate sample by typical curve, the results are shown in Table 3.
As shown in Table 3, the number percent of the total element sulfur content after each sample adds the element sulfur content of measuring behind the sulphur and adds sulphur in the sample, promptly the recovery illustrates that all near 100% the inventive method has higher accuracy.
Table 1
Table 2
Table 3
Claims (8)
1. the method for element sulfur content in the oscillopolarographic detection distillate comprises the steps:
(1) sets up typical curve: elementary sulfur and triphenyl phosphorus adding toluene are mixed with solution, making wherein, element sulfur content is 40～60 mcg/ml, the content of triphenyl phosphorus is 0.5～5.0 mg/ml, make elementary sulfur and triphenyl phosphorus in the solution fully react generation triphenylphosphine sulfide then, make storage liquid, storage liquid is become the standard solution of a series of different element sulfur contents with dilution with toluene, after getting a certain amount of standard solution and being diluted to certain volume with supporting electrolyte, polarogram peak point current with triphenylphosphine sulfide generation in the oscillopolarographic detection standard solution, the polarogram peak point current that triphenylphosphine sulfide in the standard solution of different element sulfur contents is produced is associated with the element sulfur content of solution and sets up typical curve
(2) element sulfur content of mensuration distillate sample: distillate sample and triphenyl phosphorus adding toluene are mixed with solution, the content that makes triphenyl phosphorus is 0.1～5.0 mg/ml, make elementary sulfur and triphenyl phosphorus in the solution fully react generation triphenylphosphine sulfide, press the measuring method of standard solution and measure the polarogram peak point current that triphenylphosphine sulfide produces in the distillate sample, draw element sulfur content corresponding to this peak point current by typical curve.
2. in accordance with the method for claim 1, it is characterized in that described supporting electrolyte is made up of toluene, methyl alcohol and sulfuric acid, wherein the volume ratio of toluene and methyl alcohol is 1: 1, and sulfuric acid content is 0.05～0.3 mol.
3. in accordance with the method for claim 1, the temperature of reaction that it is characterized in that described elementary sulfur and triphenyl phosphorus is 20～60 ℃, and the reaction time is 20～50 minutes.
4. in accordance with the method for claim 3, the temperature of reaction that it is characterized in that elementary sulfur and triphenyl phosphorus is 30～40 ℃, and the reaction time is 20～30 minutes.
5. in accordance with the method for claim 1, it is characterized in that preparing storage liquid or the amount of the triphenyl phosphorus that adds is 0.5～2.0 mg/ml in the distillate sample.
6. in accordance with the method for claim 1, when it is characterized in that carrying out oscillographic polarography mensuration, be that contrast electrode, platinum electrode are that auxiliary electrode, a mercury are indicator electrode with the saturated calomel electrode, initial scanning current potential is-0.1 volt.
7. in accordance with the method for claim 1, it is characterized in that described distillate is any distillate in gasoline, kerosene and the diesel oil distillate.
8. in accordance with the method for claim 1, it is characterized in that element sulfur content is 0.01～40 mcg/ml in the described distillate.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1311433A (en) * | 2000-03-03 | 2001-09-05 | 中国石油化工集团公司 | Method for measuring total active sulfur in petroleum fractions |
| CN1338631A (en) * | 2000-08-23 | 2002-03-06 | 中国石油化工股份有限公司 | Oscilloscopic polarography for measuring S element in petroleum fraction and products |
| CN1338630A (en) * | 2000-08-23 | 2002-03-06 | 中国石油化工股份有限公司 | Oscilloscopic polarography for measuring S element in crude oil |
| US20030049854A1 (en) * | 2001-09-11 | 2003-03-13 | Rhodes John R. | Method and apparatus for the on-stream analysis of total sulfur and/or nitrogen in petroleum products |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1311433A (en) * | 2000-03-03 | 2001-09-05 | 中国石油化工集团公司 | Method for measuring total active sulfur in petroleum fractions |
| CN1338631A (en) * | 2000-08-23 | 2002-03-06 | 中国石油化工股份有限公司 | Oscilloscopic polarography for measuring S element in petroleum fraction and products |
| CN1338630A (en) * | 2000-08-23 | 2002-03-06 | 中国石油化工股份有限公司 | Oscilloscopic polarography for measuring S element in crude oil |
| US20030049854A1 (en) * | 2001-09-11 | 2003-03-13 | Rhodes John R. | Method and apparatus for the on-stream analysis of total sulfur and/or nitrogen in petroleum products |
Non-Patent Citations (8)
| Title |
|---|
| 原油及其馏分油中活性硫的测定方法. 田松柏.石油化工腐蚀与防护，第16卷第1期. 1999 |
| 原油及其馏分油中活性硫的测定方法. 田松柏.石油化工腐蚀与防护，第16卷第1期. 1999 * |
| 痕量硫示波极谱的测定. 钱俊青.无锡轻工大学学报，第20卷第2期. 2001 |
| 痕量硫示波极谱的测定. 钱俊青.无锡轻工大学学报，第20卷第2期. 2001 * |
| 石油馏分及产品中元素硫的示波极谱测定. 吴梅等.石油炼制与化工，第31卷第1期. 2000 |
| 石油馏分及产品中元素硫的示波极谱测定. 吴梅等.石油炼制与化工，第31卷第1期. 2000 * |
| 示波极谱法测定水中硫化物. 瞿艳民等.河南预防医学杂志，第9卷第4期. 1998 |
| 示波极谱法测定水中硫化物. 瞿艳民等.河南预防医学杂志，第9卷第4期. 1998 * |
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