1. A method of detecting a bromine parameter, comprising: in the process of testing bromine parameters of petroleum products by adopting an electric quantity method, n-hexane is adopted to dissolve the petroleum products.

2. The method of detecting bromine parameters of claim 1 wherein the petroleum product is a petroleum product that cannot be directly drawn with a syringe;

preferably, the petroleum product comprises at least one of fischer-tropsch soft wax, heavy distillate oil and wax.

3. The method of detecting bromine parameters of claim 1 wherein the petroleum product comprises: heavy diesel oil, reduced oil and heavy distillate oil.

4. The method of detecting a bromine parameter of claim 1 wherein the bromine parameter comprises a bromine number or a bromine index.

5. The method of detecting bromine parameters of claim 1 wherein the coulometry comprises the method of SH/T0630-1996;

preferably, the method comprises the following steps: mixing a petroleum product and n-hexane to form a solution to be detected, injecting the solution to be detected into an electrolytic cell for reaction, measuring the electric quantity consumed by the electrolytic cell, and calculating the bromine number or bromine index of the sample according to a Faraday's law of electrolysis.

6. The method of detecting bromine parameters of claim 5 wherein the electrolytic cell comprises an electrolyte containing a known content of bromine;

preferably, the bromine content is below 2.

7. The method for detecting bromine parameters of claim 6, wherein the reacting the solution to be detected comprises: the unsaturated hydrocarbon in the solution to be detected and bromine in the electrolyte undergo the following reactions:

8. the method of claim 7, wherein the amount of power consumed is the amount of power consumed to electrolytically replenish bromine, wherein the replenished bromine is the bromine electrolytically replenished at the electrolytic anode, and the reaction is carried out with reference to the following formula, followed by replenishing bromine: 2Br^--2e—→Br₂。

9. The method for detecting bromine parameters of claim 5, wherein the volume ratio of petroleum product to n-hexane is 1: 8-12.

10. A method of evaluating the quality of a petroleum product, comprising: the method of detecting a bromine parameter of any one of claims 1-9.

Background

In the prior art, a method for detecting bromine number or bromine index in a petroleum product is generally adopted by SH/T0630-1996, but when the method is adopted to detect some petroleum products which can not be directly extracted by a syringe at room temperature (25-30 ℃), for example, non-liquid petroleum products including but not limited to heavy diesel oil, reduced oil and heavy distillate oil need to be dissolved by benzene and then detected, but the bromine index or bromine number obtained by detecting by dissolving the benzene is inaccurate, and the adopted solvent has high toxicity, so that the method can not be applied in large scale, or even if the method is applied, the method needs strict operation of operators, and the operation difficulty of the operators is increased.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The invention aims to provide a method for detecting bromine parameters and a method for evaluating the quality of petroleum products.

The invention is realized by the following steps:

in the prior art, an electric method is generally adopted, for example, SH/T0630-1996, bromine parameters of petroleum products are tested, but benzene adopted in the detection process dissolves some petroleum products which cannot be directly extracted by a syringe and then can be detected, but benzene is not only toxic, but also benzene cannot completely dissolve the petroleum products to be detected, and the detection result is easy to cause inaccuracy.

In a first aspect, the present invention provides a method for detecting bromine parameters, comprising: in the process of testing bromine parameters of petroleum products by adopting an electric quantity method, n-hexane is adopted to dissolve the petroleum products.

In an alternative embodiment, the petroleum product is a petroleum product that cannot be directly extracted with a syringe, for example, the petroleum product includes at least one of fischer-tropsch soft wax, heavy distillate oil, and wax. Specifically, the condensation point of Fischer-Tropsch soft wax and heavy distillate oil is 37-42 ℃, and the Fischer-Tropsch soft wax and heavy distillate oil is in a semi-solidified state at normal temperature; the Fischer-Tropsch soft wax mainly comprises C16-C40, and the heavy distillate oil mainly comprises C12-C33, and has heavier components. Meanwhile, the wax can be dissolved by using normal hexane, heating is needed during dissolving (only a blower is used), the main component C15-C70 is used, and when a sample is analyzed, the temperature is slightly over room temperature after the sample is completely dissolved, so that the sample can be analyzed without turbidity.

In an alternative embodiment, the petroleum product comprises: heavy diesel oil (soft wax), reduced oil, and heavy distillate oil.

In alternative embodiments, the bromine parameter comprises bromine number or bromine index.

In alternative embodiments, the coulometric methods include the methods in SH/T0630-1996;

preferably, the method comprises the following steps: mixing a petroleum product and n-hexane to form a solution to be detected, injecting the solution to be detected into an electrolytic cell for reaction, measuring the electric quantity consumed by the electrolytic cell, and calculating the bromine number or bromine index of the sample according to a Faraday's law of electrolysis.

In an alternative embodiment, the electrolytic cell includes an electrolyte containing a known content of bromine;

preferably, the bromine content is below 2.

In an alternative embodiment, the subjecting the solution to be tested to a reaction comprises: the unsaturated hydrocarbon in the solution to be detected and bromine in the electrolyte undergo the following reactions:

in an alternative embodiment, the amount of electricity consumed is the amount of electricity consumed to electrolytically replenish bromine, wherein the replenished bromine is electrolytically replenished bromine at the electrolytic anode.

In an alternative embodiment, the reaction is carried out with reference to the following formula followed by bromine supplementation: 2Br- -2 e- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -₂。

In an alternative embodiment, the volume ratio of petroleum product to n-hexane is from 1:8 to 12.

In a second aspect, the present invention provides a method of evaluating the quality of a petroleum product, comprising: the method of detecting a bromine parameter of any of the preceding embodiments.

The invention has the following beneficial effects: according to the method for detecting the bromine parameters, provided by the embodiment of the invention, the benzene used for dissolving petroleum products in the detection process by an electric quantity method is replaced by n-hexane, so that the accuracy of the detected bromine parameters such as bromine number, bromine index and the like can be effectively improved, meanwhile, the toxicity of the detection method is reduced, and the health of operators is favorably improved.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Bromine parameters generally include bromine number and bromine index, and bromine number refers to: the gram number of bromine consumed when reacted with 100g of a sample under predetermined conditions is represented by gBr/100 g. The bromine index refers to: the amount of bromine consumed in mg when reacted with 100g of a sample under the predetermined conditions is expressed as mgBr/100 g. In the prior art, an electric method is generally directly adopted, such as SH/T0630-1996, for detecting petroleum products, such as gasoline, lubricating oil, diesel oil, kerosene, light aromatic hydrocarbon and the like, wherein part of the petroleum products can be directly extracted by a syringe and then injected into an electrolytic cell for reaction, and the bromine index and the bromine number are detected. But there is some petroleum products can't adopt the direct extraction of syringe, then can't inject into the electrolytic bath and carry out the reaction, consequently, need adopt benzene to dissolve, just can extract with the syringe, then can experiment, but adopt benzene to have accurate many problems, for example the testing result is inaccurate and benzene toxicity is high, causes adverse effect to operating personnel's health easily.

Specifically, benzene (benzzene, C6H6) organic compounds, formula: c₁₂H₁₀Molecular mass: 154.21, boiling point: 255 ℃, melting point: 68.5-71 ℃. The aromatic hydrocarbon is the simplest aromatic hydrocarbon, is colorless and sweet transparent liquid at normal temperature, has density lower than that of water, and has strong aromatic smell. It is flammable and toxic and is a carcinogen of the first class of IARC. Benzene is insoluble in water and easily soluble in organic solvents, and can be used as an organic solvent. Half of the lethal dose (rat, oral) is 3800 mG/kG. Has carcinogenic potential. Less dense than water. Toxicology data: LD50:3306mg/kg (oral in rat); 48mg/kg (mouse transdermal), LC50:10000ppm for 7 hours (rat inhalation). The sensitivity to benzene is different because of the different health conditions and contact conditions of each person. When the benzene smell is smelled, its concentration is about 1.5ppm, and the risk of poisoning should be noted. In the examination, the degree of benzene poisoning can be easily detected by examining urine and blood. Contact limit: 40mg/m³(transdermal).

In view of this, an embodiment of the present invention provides a method for detecting a bromine parameter, including: in the process of testing bromine parameters of petroleum products by using SH/T0630-1996, n-hexane is used for dissolving the petroleum products. n-Hexane-English name n-Hexane, molecular formula CH₃(CH₂)₄CH₃Molecular weight 86.17. Colorless transparent liquid, easy to volatilize. Specific gravity 0.65937(20/4 deg.C), boiling point 68.742 deg.C, melting point-95 deg.C, refractive index 1.37486(20 deg.C); flash point-9 ° F. Soluble in alcohols, ketones and ethers, insoluble in water. The application is as follows: mainly used as a solvent, such as a solvent in vegetable oil extraction, a solvent in olefin polymerization (such as a solvent of polypropylene), a diluent of a pigment and the like. N-hexane is of low toxicity, and the safe concentration of n-hexane is less than 180mg/m³。

According to the embodiment of the invention, n-hexane is used as a dissolving solvent, so that the petroleum product can be effectively and completely dissolved, and the accuracy of a detection result of the bromine index or the bromine number is improved. Meanwhile, the solvent is obviously less toxic than benzene, and the personal safety of operators can be effectively ensured.

In particular, the petroleum product is one that cannot be directly extracted with a syringe. Such as any one of heavy diesel, reduced oil and heavy distillate. The substances are extremely high in viscosity and difficult to extract at normal temperature, or the substances are solid and cannot be directly extracted by an injector, and then are injected into an electrolytic cell for reaction.

Therefore, a heavy dilution method is adopted to obtain a substance which can be directly extracted by an injector, and then detection is carried out, specifically, a petroleum product and n-hexane are mixed to form a solution to be detected, the volume ratio of the petroleum product to the n-hexane is 1:8-12, if the proportion of the petroleum product to be detected is changed, the petroleum product cannot be completely dissolved, and the accuracy of the detected bromine value or bromine parameter is influenced.

Then injecting the solution to be detected into an electrolytic cell for reaction, and then reacting unsaturated hydrocarbon in the solution to be detected with bromine in the electrolyte as follows:

the bromine consumed by the reaction is supplemented by electrolysis of an electrolysis anode, and the method comprises the following steps: 2Br- -2 e- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -₂. And then the electric quantity consumed by electrolyzing the supplemented bromine can be measured, and the bromine value or the bromine index of the sample can be calculated according to the Faraday's law of electrolysis.

Wherein the electrolytic cell comprises an electrolyte containing a known content of bromine; the bromine content is below 2.

The method can accurately detect the bromine parameters of petroleum products, particularly heavy petroleum distillate oil which can not be directly extracted by an injector and some non-liquid petroleum products, and the detection method is safer and can be widely used.

The embodiment of the invention also provides a method for evaluating the quality of petroleum products, which comprises the following steps: the method of detecting a bromine parameter of any of the preceding embodiments.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

The embodiment of the invention provides a method for detecting and reducing oil bromine index, which comprises the following steps:

the ingredients of the reduced oil are as follows:

specifically, the reduced oil is dissolved in a solvent, the volume is fixed to a 100ml iodine measuring flask, 1ml of reduced oil diluent is transferred to a bromine index electrolytic cell by using a syringe, the density is calculated according to a rho density-m mass/v volume formula, and then the bromine index is calculated according to a Faraday's law of electrolysis according to the measured electric quantity. The results are given in the following table:

carbon disulfide is easy to volatilize, has high toxicity, is second to benzene and is excluded from use.

Example 2

The embodiment of the invention provides a method for detecting a Fischer-Tropsch soft wax bromine index, which comprises the following steps:

the Fischer-Tropsch soft wax has the following composition:

specifically, the Fischer-Tropsch soft wax is dissolved in a solvent, the volume is fixed to a 100ml iodine measuring flask, 1ml of Fischer-Tropsch soft wax diluent is transferred to a bromine index electrolytic cell by using an injector, the density is calculated according to a rho density-m mass/v volume formula, and then the bromine index is calculated according to a Faraday's law of electrolysis according to the measured electric quantity. The results are given in the following table:

as can be seen from the above table, Fischer-Tropsch soft wax is semisolid at normal temperature and cannot be directly analyzed by using a syringe. Different solvents are respectively dissolved in Fischer-Tropsch soft wax to determine the bromine index of the soft wax, normal hexane is closest to carbon disulfide, but the carbon disulfide is volatile, errors generated in the test are large, no normal hexane is stable, and the toxicity of the normal hexane is minimum. Benzene is the most toxic and contains bromine itself with a high measured bromine index.

Experimental example 1

The experimental example of the invention provides a method for detecting a bromine index of a standard substance, which comprises the following steps:

the standard substances are: standard substance for measuring bromine index of institute of petrochemical science, GBW (E) 060116.

Specifically, the standard substance is dissolved in a solvent, the volume is fixed to a 100ml iodine measuring flask, 1ml of standard substance diluent is transferred to a bromine index electrolytic cell by using an injector, the density is calculated according to a rho density-m mass/v volume formula, and then the bromine index is calculated according to a Faraday's law of electrolysis according to the measured electric quantity. The results are given in the following table:

according to the results, when benzene is used as a solvent for bromine index detection, the detection value is real and higher by more than 15%, but the normal hexane provided by the embodiment of the invention has a certain difference with the real content, but is closer to the real value, and meanwhile, when alkane such as isooctane or n-decane is used, the difference with the real value is larger, which shows that the embodiment of the invention specifically uses normal hexane as a dissolving solvent, so that the bromine index can be detected more accurately.

Experimental example 2

The method of example 1 was used to test heavy distillates of known bromine parameters to verify that n-hexane solvent was superior to benzene solvent. The bromine index of the heavy distillate oil is 221.69mgBr/100g, the bromine index content is calculated according to the olefin content of 0.1262 Xbromine content +0.0279 Xdensity (the formula quotes the article number of 'rapidly and accurately measuring the olefin content in naphtha by using bromine value and density', J1007-1865 (2013)) 05-0047-02, the density is 0.799g/cm3, and the olefin content is 28.

The composition of the heavy distillate is as follows:

the detection results are as follows:

according to the results, the n-hexane is most similar to the true value, and the toxicity is lower than that of other solvents.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.