US 4,988,446 A · Method for spectroscopic analysis of hydrocarbons

Abstract

A sample of a hydrocarbon oil containing asphaltenes is chromatographically analyzed by forming a mixture of the oil with a weak solvent. The mixture is passed in contact with a column of a stationary phase of fine solid particles of fully functionalized material, followed by a weak solvent. The solvent, after recovery from the column, is analyzed for aromatics by UV-absorption of UV radiation in the range 200 to 400 nm. The absorbance of the UV light by the irradiated eluents across the UV wavelength range is monitored and the integral of absorbance is derived as a function of photon energy across the wavelength range. The magnitude of the derived integral in at least one time interval corresponding with aromatics in the eluent from the stationary phase is measured as an indication of the level of aromatics in the oil sample. The weak solvent may be followed by a strong solvent which, in turn, may be followed by a strong solvent which is modified by the addition of a hydrogen bonding solvent.

Claims23

Dependent claims

A method for quantifying the aromatic core content of a hydrocarbon containing solution containing more than one aromatic compound comprising the steps of:

(a) passing a solution of hydrocarbon oil and a carrier phase in contact with a chromatographic stationary phase over a first time interval so as to retain components of siad hydrocarbon oil on said stationary phase;
(b) passing a mobile phase in cotact with said stationary phase after step (a) over a second time interval, for eluting different retained components of said oil from said stationary phase at different time intervals, and recovering the mobile phase which has contacted the stationary phase together with the compnents eluted from the stationary phase;
(c) irradiating recovered solution with UV light having a wavelength range of which at least a portion is within the range of about 200 nm to about 500 nm,
(d) measuring the absorbance of the UV light by the aromatic cores in the recovered solution,
(e) deriving the integral of absorbance as a function of photon energy across the energy corresponding to the wavelength range, and
(f) comparing the absorbance integral to a predetermined value, thereby quantifying the aromatic core content.

3 more elements

A method for the chromatographic analysis of a hydrocarbon oil comprising the steps of:

(a) passing a mixture of the hydrocarbon oil and a carrier phase in contact with a first and second stationary phase over a time interval so as to retain the components of the hydrocarbon oil on the stationary phases wherein the first stationary phase comprises surface hydroxyl groups substantially all of which have been substantially fully functionalized with a charge transfer functionality selected from the group consisting of trinitroanilino propane, tetrachlorophthalimido propane, dinitrobenzoyl glycidyl propane and tetranitrofluorenone and the second stationary phase comprises surface hydroxyl groups at least a portion of which have been substantially fully functionalized by a functionality selected from the group consisting of aminopropyl, cyanopropyl, nitropropyl and a combination thereof;
(b) passing in contact with the first and second stationary phases a mobile phase of a weak solvent having a solubility parameter of 7.0 to 7.8 cal.sup.0.5 /cm.sup.1.5 for a second time interval sufficient to elute saturates and mono aromatics from the first stationary phase;
(c) continuing passing the weak solvent to the second stationary phase for a third time interval sufficient to complete substantially the elution of mono aromatics;
(d) recovering solvent passed to the first and second stationary phases;
(e) monitoring solvents recovered in step (d) and detecting at least saturates, mono aromatics, and aromatics of 2 or more rings.

2 more elements

A method for the chromatographic analysis of a hydrocarbon oil comprising the steps of:

(a) passing a mixture of the hydrocarbon oil and a carrier phase in contact with a first and second chromatographic stationary phase over a time interval so as to retain the components of the hydrocarbon oil on the stationary phases;
(b) passing in contact with the first and second stationary phases a first mobile phase of a weak solvent having a solubility parameter from 7.0 to 7.8 cal.sup.0.5 /cm.sup.1.5 for a second time interval sufficient to elute saturates and mono aromatics from the first stationary phase;
(c) bypassing the first stationary phase and continuing passing the weak solvent to the second stationary phase for a third time interval sufficient to complete substantially the elution of mono aromatics;
(d) bypassing the second stationary phase and passing the weak solvent to the first stationary phase for a fourth time interval sufficient to elute 2-ring aromatics;
(e) passing solvent of increased strength to the first stationary phase for a fifth time interval sufficient to elute 3-ring aromatics;
(f) passing solvent of a strength greater than in step (e) to the first stationary phase for a sixth time interval sufficient to elute 4-ring aromatics;
(g) passing solvent of a strength greater than in step (f) to the first stationary phase for a seventh time interval sufficient to elute polar compounds;
(h) recovering the solvent from each of steps (b)-(g);
(i) monitoring the solvents recovered in step (h) and detecting saturates, mono aromatics, 2-ring aromatics, 3-ring aromatics, 4-ring aromatics, and polars.

6 more elements

Dependencies are inferred from the claim text.

Method for spectroscopic analysis of hydrocarbons

Life of this patent

Method for spectroscopic analysis of hydrocarbons

Life of this patent

Abstract

Claims23