Petrochemicals

Determination of Sulphur in Oil and Oil Products

X-ray fluorescent energy dispersive sulfur analyzer ASE-2 and X-ray wavelength dispersive sulfur analyzer ASW-2

The important analytical task related to ecology and environment protection is the determination of sulphur content in oil and oil products. Wide use of various fuels based on oil (gasoline, kerosene, oil fuel, etc.), by road, marine and aircraft transport vehicles, for energy production by heat power plants leads to atmosphere contamination with combustion products, first of all with sulfur dioxide, which causes acid rains that deteriorate soil fertility and threaten humans’ health directly.

Therefore the existing standards of all countries regulate the sulphur content in oil and in the oil-based fuel strictly.

The new standards of leading countries reduce the sulphur maximum admissible concentrations in gasoline and diesel fuel down to 30-10 mg/kg and less whereas earlier the sulphur content of about 100 – 150 mg/kg (0.01 – 0.015 %) was considered to be quite acceptable.

The X-ray fluorescence method is a reference method for determination of the sulphur weight fraction in oil and various oil products; in particular, it enables analyzing the diesel fuel, kerosene and automotive fuel of all classes.

To determine the weight fraction of total sulphur in oil, oil fuel, motor gasoline (class K2), diesel fuel (class K2 and K3) and in jet and marine fuels, aircraft gasoline, the reference method is the one as per GOST R 51947-2002 (ASTM D 4294-98) “Standard Test Method for Sulfur in Petroleum Products by Energy-Dispersive X-Ray Fluorescence Spectroscopy” that defines the sulphur weight fraction quantitative measurement range of 150 mg/kg – 50*103mg/kg.

Along with Russian GOST R 51947-2002, standard GOST R EN ISO 20847-2010 is also applicable because it states the method of sulphur content determination in the range of 30 to 500 mg/kg in motor gasolines classes К2, К3, К4, including those containing oxygen of up to 2.7% by weight, and in diesel fuels, including those containing FAME of up to 5% by vol., with the help of energy dispersive X-ray fluorescence spectrometry. According to the Customs Union technical regulations 013/2011 dated 18.11.11 and STB 2141-2010, GOST R EN ISO 20847-2010 may be referred to when determining the sulphur weight fraction in diesel fuel of classes К2, К3, К4.

To determine the sulphur weight fraction in motor gasoline of classes К3, К4, К5, diesel fuel of classes K4 and K5, the reference method is the one stated by GOST R 52660-2006 (EN ISO 20884:2004) “Petroleum products. Determination of sulfur content of automotive fuels by Wavelength-dispersive X-ray fluorescence spectrometry” and addition # 1 dated 01.07.15, the range of sulphur weight fraction quantitative measurement is 5 mg/kg – 500 mg/kg. In addition to the said method, the method as per GOST R 53203-2008 (ASTM D 2622-05) defining the sulphur weight fraction quantitative measurement range of about 3 mg/kg to 53*103mg/kg, to analyze crude oil, diesel and jet fuel, kerosene, base lubricant and methanol fuels М-85 and М-100.

GOST R EN ISO 14596-2008 is applicable to hydrocarbon oils, additives to oil products, semi-solid and solid oil products that liquefy when exposed to moderate heating or are solved in organic solvents with minor or known content of sulphur, and defined the method of sulphur content determination in the range of 0.001% by weight to 2.50% by weight. In particular, this method is applicable for jet fuel analysis according to the Customs Union technical regulations 013/2011 dated 18.11.11.

The standard methods mentioned in this section allow measuring the sulphur weight fraction without sample preparation, that is, an oil product sample put into a special cell is analyzed as it is.

Thus, a potential Customer may choose a proper instrument from a range X-ray fluorescence sulphur analyzers by Bourevestnik, Inc. – an instrument ensuring a legitimate solution to the analytical task of sulphur weight fraction measurement in oil products according to effective Russian and foreign normative documents.

X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F

One of the most important analytical tasks of petrochemistry is determination of the sulphur content in oil products. First of all, it is related to ecology and environmental protection. Wide use of various fuels based on oil, which current annual production is over 4 bln. tons (gasoline, kerosene, oil fuel, etc.), by road, sea and aircraft transport vehicles, for energy production by heat power plants lead to atmosphere contamination with sulfur dioxide. This causes acid rains that deteriorate soil fertility and threaten humans’ health directly.

According to the sulphur content, the standard divides oil into 4 classes, which characteristics are given in Table.

Oil classDescriptionSulphur weight fraction, %
1Sweet oilup to 0.60 incl.
2Sulfur-bearing oil0.61 to 1.80
3Sour oil1.81 to 3.50
4Super sour oilover 3.51

Since the sulphur content in best oil grades is 0.5%, in Urals oil – about 1.3%, and in Tatarstan oil reaches even 2-4%, oil refinery and cracking plants have to apply and monitor a desulphuration procedure. Further desulphuration is performed during production of certain fuel types. Desulphuration of automotive fuel (gasoline and diesel fuel) is vital, since the sulphur available therein corrodes engines, thus reducing the vehicle lifetime and poisoning the air of cities.

Therefore the existing standards of all countries regulate the sulphur content in oil and in the oil-based fuel strictly.

The X-ray fluorescence method is a reference method for determination of the sulphur weight fraction in oil and various oil products; in particular, it enables analyzing the diesel fuel, kerosene and automotive fuel of all classes. It is a rapid method that requires no sample preparation for analysis.

According to existing standards, both energy dispersive and wave dispersive XRFA may be used. Energy dispersive XRFA standards require using detectors with the resolution £ 0.8 keV at Mn Ka line (that is, proportional counters and SSD), but there are no data on use of SSD for sulphur determination in oil products. One may expect SDD to make the determination limit even lower.

Requirements to the sulphur lower limit of quantitative determination tend to grow each year: from 150 mg/kg in 2002, to 30 mg/kg in 2010 and from 10 mg/kg in 2002 to 5 mg/kg in 2012.

The determination limit is the concentration equalling to the between-laboratory precision at P=0.95 (with 1.3-2 times as low precision).

To determine the sulphur weight fraction in motor gasoline of classes К3, К4, К5, diesel fuel of classes K4 and K5, the reference method is the one stated by GOST ISO 20884-2012.

Determination of Chloride Salts in Oil

X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F

Requirements to the content of chloride salts are defined in the standard [GOST 21534-76]. The oil is divided into three groups, with the chloride salts content limit defined for each group. This value is 100, 300 and 900 mg/dm3 for the first, second and third groups, correspondingly. To perform XRFA chloride salts shall be first withdrawn from oil using water. A withdrawn amount is then put into a spectrometer cell and analyzed. Since the Rh K line overlaps the chlorine analytical line to reduce the chlorine determination limit, an X-ray tube with a palladic or silver anode should be used.

Determination of Chlorine and Bromine in Oil and Hydrocarbon Oils

X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F

The wave dispersive XRFA is used to determine low contents of Cl and Br chemically bound with oil hydrocarbons. The ranges of detectable contents of these elements are from 0.0005 to 0.1 % for Cl and from 0.001 to 0.1% for Br. These contents may be measured with an energy dispersive instrument.

Determination of Metal in Oil and Oil Products

X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F

The microelement composition of oil is an important characteristics of this raw material. First, it bears the geological and geochemical data and, in particular, shows the oil age, routes and directions of its migration and accumulation. Differences in the content of microelements in oil may be used for identification of oil beds and recommendations for use of wells. Second, the oil is likely to become the raw material for production of vanadium, nickel and some other metals in the nearest future due to the available trend of depletion of ore beds. Third, the microelements present in oil, first of all V, may have a substantial impact on oil refining processes and cause catalyst poisoning. Use of oil products containing metals as fuel leads to emission into atmosphere of their toxic compounds. Use thereof as lubricants causes corrosion of engine’s active elements. The above factors reveal the necessity of research of the oil microelement composition to the benefit of certain national economy branches.

The content of the most frequent elements in oil – V and Ni – varies from fractions of g/t to 6 kgг/t for V and to 350 g/t for Ni. The average content of these elements in Russian oils is about dozens of g/t.

These elements are detected by the wave dispersive XRFA method. According to the approximate calculation, instrument BRA-135 will allow detecting vanadium and nickel in oils and fuels with the proper precision and determination limit of several g/t.

Both wave dispersive and energy dispersive XRFAs are used for control of the content of 29 chemical elements in liquid cracking catalysts [ASTM D7085-04(2010)e1. – Standard Guide for Determination of Chemical Elements in Fluid Catalytic Cracking Catalysts by X-ray Fluorescence Spectrometry (XRF)]. If necessary, other elements may be added to detectable ones. Both new catalysts and those in use and dead ones require analysis for wear products. Regardless of the XRFA type, the standard implies analysis of compacted samples and samples fused with borate flux agent.

Determination of ceramic`s component in catalytic converters.

X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F

To control the composition of ceramic post-combustion catalysts used for reduction of the vehicle exhaust toxicity, the energy dispersive XRFA is also appropriate. These catalysts include ceramic based on oxides of several elements (Al, Si, Ti, Ca, Mn) and containing 1 -3% to dozens % of each metal and 0.05-0.15% of platinum-group metal (usually, Pt or Pd). Both the starting ceramic and dead catalysts used for recovery of precious metals are subject to analysis.

Determination of Pb, Mn and Fe in Motor Gasoline

X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F

According to Decree of the Russian Federation Government dated February 27, 2008, No. 118, on approval of the technical regulation “On requirement to motor and aviation gasoline, diesel and marine fuels, jet fuel and reduced fuel oil”, these metals are prohibited in the motor gasoline. Determination of low contents of lead (from 0.0026 g/dm3) is performed by the wave dispersive XRFA using the internal standard (Bi) or, if the spectrometer is fitted with a tube with a tungsten anode, by the background-standard method (relation of line Pb L1 intensity to intensity of incoherently spattered line W L). Nowadays determination of all these elements usually are subject to apply a more sensitive but no easy and more labor-consuming optical absorption spectrometry (OAS) analysis. We believe that rapid determination of motor gasoline for all these contaminants could be performed by means of BRA-135.

Determination of Al, Si, Ca, Fe, V, Ni in Marine Fuels

X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F

The ash remaining after fuel combustion contains solid particles of oxides (of Al, Si, Ca, Fe, V, Ni) that may lead to damage of marine engine parts (piston heads, exhaust valves, supercharger blade surface, surface partitions of boilers superheater and heater tubes). The control of these components’ weight fractions in marine fuel is required by technical regulations [GOST R 54299-2010. Marine fuels. Technical regulations]. This control may be performed with spectrometer BRA-135. V and Ni available in marine fuel in solution as organic compounds may be detected in a sample put into the instrument cell. To detect compounds of other elements available as fine particles, the test charge needs pre-filtering through VLADIPOR membrane with a pore diameter of about micron fractions. To improve filtration, the test charge is to be diluted with hydrocarbon solvent. Then the filter is dried and analyzed.

Analysis of Lubricant Additives

X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F

Lubricants may include Zn, P, Ca, S, Mg, Ba, Sr, Mo. There are quite high concentrations of these elements in lubricants and therefore they are detectable by the X-ray fluorescence method without sample preparation. The unused lubricants may be analyzed for ultimate composition both at the lubricant manufacturing stage for the purpose of formulation control and at acceptance tests. 

Determination of the mineral composition of rocks

General-Purpose X-ray diffractometers DRON-7 and DRON-8

Diffractometers DRON-7 and DRON-8 are used for control of phase composition and structural condition of raw materials and organic and non-organic synthesis products during a manufacturing process. The diffractometers have found wide use in catalysis and electrochemical industry.