METHOD FOR SELECTIVE REMOVAL OF POLYCYCLIC AROMATIC HYDROCARBONS FROM OILS OBTAINED AS A RESULT OF PETROLEUM PROCESSING

Abstract

A method for selective removal of polycyclic aromatic hydrocarbons from oils obtained as a result of petroleum processing, including two separate processes: filtration through a porous carbon-containing bed comprising and filtration through microfiltration membranes. The method is particularly useful for purifying oils selected from unconverted oils obtained in hydrocracking processes, products of further processing of these oils, engine oil and used engine oil.

Claims

1. A method for selective removal of polycyclic aromatic hydrocarbons from oils obtained as a result of petroleum processing, characterised in that it comprises two separate processes: filtration through a porous carbon-containing bed comprising and filtration through microfiltration membranes.

2. The method according to claim 1, characterised in that the oils obtained as a result of petroleum processing are selected from: unconverted oils obtained in hydrocracking processes, products of further processing of these oils, engine oil and used engine oil.

3. The method according to claim 1, wherein the filtration is carried out on the carbon-containing bed in granulated or powdered form having extended surface of 500-1600 m.sup.2/g.

4. The method according to claim 1, wherein the filtration is carried out on the carbon-containing bed having grain size of 0.3-4 mm.

5. The method according to claim 1, wherein the filtration process temperature on the carbon-containing bed ranges from 10 to 90° C.

6. The method according to claim 5, wherein the filtration process temperature on the carbon-containing bed ranges from 17 to 65° C.

7. The method according to claim 1, wherein the filtration is carried out on the carbon-containing bed at linear velocity ranging from 1 to 10 m/min.

8. The method according to claim 1, wherein the filtration is carried out on the microfiltration membranes with the nominal pore size ranging from 0.1 to 1.2 micrometers.

9. The method according to claim 1, wherein the filtration is canned out on the microfiltration membranes with the nominal pore size ranging from 0.1 to 0.5 micrometers.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0021] The present disclosure in exemplary embodiment was illustrated in a drawing. FIGURE 1 shows a schematic diagram of realisation of the method according to the aspects of the disclosed embodiments.

EXPERIMENTS

[0022] Following tests were carried out, which according to the authors show high efficiency in solving the problem.

[0023] Oil sample used in all the tests had the physicochemical properties as shown in the following table.

TABLE-US-00001 Appearance at temp. 20° C. clear, straw-yellow colour Appearance at temp. 20° C. no suspensions Density g/cm.sup.3 15° C. 0.8456 Absorbance at wavelength of 385 nm 1.0925 in isooctane solution Kinematic viscosity at 100° C. cSt 5.24 Kinematic viscosity at 40° C. cSt 27.9 Viscosity index 121 Sulphur content %(m/m) 0.006

Test 1

[0024] An oil sample was subjected to an in-depth oxidation by means of UV radiation and titanium dioxide as a catalyst. Irradiation time was 30 minutes.

[0025] Resultant sample was filtered in a cross-flow filtration system using a system of single-stage filtration on microporous membranes.

Test 2

[0026] An oil sample was subjected to an in-depth oxidation by means of UV radiation and titanium dioxide as a catalyst. Irradiation time was 42 minutes.

[0027] Resultant sample was filtered in a cross-flow filtration system using microfiltration membranes.

[0028] Further the sample was filtered through a four-stage integrated filtration system.

[0029] Resultant sample was filtered in a cross-flow filtration system using nanofiltration membranes.

Test 3

[0030] An oil sample was filtered through a three-stage integrated filtration system using carbon-containing bed and filtration on filtration membranes.

Test 4

[0031] An oil sample was filtered through a two-stage integrated filtration system using carbon-containing bed and filtration on filtration membranes.

Test Results

[0032]

TABLE-US-00002 Test 1: Appearance at temp. 20° C. clear, dark straw-yellow colour Appearance at temp. 20° C. no suspensions Density g/cm.sup.3 15° C. 0.8456 Absorbance at wavelength of 385 nm 0.9882 in isooctane solution Kinematic viscosity at 100° C. cSt 5.236 Kinematic viscosity at 40° C. cSt 27.92 Sulphur content %(m/m) 0.0063

TABLE-US-00003 Test 2: Appearance at temp. 20° C. clear, dark straw-yellow colour Appearance at temp. 20° C. no suspensions Density g/cm.sup.3 15° C. 0.8456 Absorbance at wavelength of 385 nm 0.0466 in isooctane solution Kinematic viscosity at 100° C. cSt 5.804 Kinematic viscosity at 40° C. cSt 32.63 Sulphur content %(m/m) 0.004

TABLE-US-00004 Test 3: Appearance at temp. 20° C. clear, dark straw-yellow colour Appearance at temp. 20° C. no suspensions Density g/cm.sup.3 15° C. 0.8456 Absorbance at wavelength of 385 nm 0.0970 in isooctane solution Kinematic viscosity at 100° C. cSt 5.811 Kinematic viscosity at 40° C. cSt 32.43 Sulphur content %(m/m) 0.0044

TABLE-US-00005 Test 4: Appearance at temp. 20° C. clear, dark straw-yellow colour Appearance at temp. 20° C. no suspensions Density g/cm.sup.3 15° C. 0.8456 Absorbance at wavelength of 385 nm 0.5512 in isooctane solution Kinematic viscosity at 100° C. cSt 5.513 Kinematic viscosity at 40° C. cSt 29.8 Sulphur content %(m/m) 0.0052

Discussion of the Results

[0033] Basic parameter defining the PAH separation degree was UV absorbance of isooctane solutions of the same concentration at different wavelengths. In the tables above absorbance results were provided for a single wavelength.

[0034] Absorbance value at wavelength of 385 nm in isooctane solution being lower than 0.1500 can be considered a satisfactory result.

Test 1

[0035] Absorbance at wavelength of 385 nm in isooctane solution changed slightly (the change was within the margin of error)

[0036] The colour of resultant filtrate was much darker than the starting oil sample.

Test 2

[0037] The absorbance value obtained at wavelength of 385 nm in isooctane solution amounting to 0.0466 can be considered very good.

Test 3

[0038] The result of test 3 is satisfactory, absorbance at wavelength of 385 nm in isooctane solution changed significantly and amounted to 0.0970.

Test 4

[0039] The result of test 4 may be considered unsatisfactory. The sample obtained in test 4 the absorbance at wavelength of 385 nm in isooctane solution was reduced merely to 0.5512.

Conclusions

[0040] Polycyclic aromatic hydrocarbons (PAHs) have molar weights similar to saturated hydrocarbons constituting the components of oils obtained as a result of petroleum processing, including unconverted oils obtained in hydrocracking processes and products of further processing of these oils. Separating PAHs from saturated hydrocarbons by means of filtration membranes only did not give expected separation results.

[0041] The most preferred is the method used in test 3.