GB2030564A

GB2030564A - Isolation of vanadyl porphyrins from a mixture thereof with hydrocarbons and/or heterohydrocarbons

Info

Publication number: GB2030564A
Application number: GB7928943A
Authority: GB
Original assignee: BP PLC
Current assignee: BP PLC
Priority date: 1978-09-05
Filing date: 1979-08-20
Publication date: 1980-04-10
Also published as: GB2030564B

Abstract

Vanadyl porphyrins are isolated from admixture with hydrocarbons and/or hetero hydrocarbons by a combination of steps including adsorption on silica, adsorption on alumina and adsorption on a functionalised solid product. The latter may be prepared from an inorganic oxide containing surface hydroxyl groups, e.g., silica, by reacting the oxide in a first stage with a haloalkoxy- or haloaryloxy-silane. The first stage product is then reacted with an aqeuous solution of an inorganic sulphite to give a product containing sulphonate groups. These can be converted to sulphonic acid groups by an optional third stage treatment with dilute mineral acid. Suitable sources of vanadyl porphyrins are crude oils and fractions thereof, particularly residue fractions.

Description

SPECIFICATION Separation process This invention relates to a method for the isolation of complex organometallic compounds from liquid hydrocarbons and in particular to a method for the isolation of vanadyl porphyrins from crude petroleum.

Porphyrins have a basic structure which is essentially four pyrrole rings joined by methyne groups.

A typical class is known as etioporphyrins. These have the following structure wherein Rt-R8 represent alkyl groups:

They form very stable complexes with metals, particularly vanadium and nickel. Such complexes are often associated with crude oils, particularly highly asphaltic crude oils. When crude oil is fractionated the porphyrin complexes are to be found in residues.

It is known that certain substances have the property of preferentially adsorbing certain types of hydrocarbons and/or hydrocarbons containing hetero atoms. For example, alumina has been extensively used as a packing for chromatographic columns.

British patent specification 1023844 discloses the use of silica gel to separate aromatic hydrocarbons from n-paraffins by preferential adsorption. In addition there is the well known clay finishing treatment used in lubricating oil production to remove unstable impurities by adsorption.

In general it is the more highly polar and more unsaturated materials which are preferentially adsorbed.

Our co-pending application No. 35566/78, discloses a process for the preparation of a functionalised solid product, derived from an inorganic oxide containing surface hydroxyl groups, containing groups of general formulae (I) and/or (II),

wherein R is a divalent radical containing up to 20 carbon atoms, R' and R2 are alkoxy groups containing up to 20 carbon atoms, or hydrolysis products thereof, M is metallic or hydrogen ion and (a) is an integer corresponding to the valency of M, which process comprises reacting an inorganic oxide containing surface hydroxyl groups in a first stage with a compound of formula (III):

wherein R, R' and R2 are as hereinbefore defined, Y is a halogen atom or an alkoxy or aryloxy group containing up to 20 carbon atoms and X is a halogen atom; and reacting the product of the first stage in a second stage with an aqueous solution of a water soluble inorganic sulphite to form a sulphonate salt; and optionally reacting the sulphonate salt of the second stage with dilute mineral acid in a third stage to form a product containing sulphonic acid groups.

We have now discovered that vanadyl porphyrins can be isolated from admixture with hydrocarbons and/or hetero hydrocarbons by a combination of steps including adsorption on silica, adsorption on alumina and adsorption on functionalised products containing sulphonic acid groups. It is surprising that in the third stage the porphyrins are in the first fractions to be eluted and are not retained by the column as one would expect.

Thus according to the present invention there is provided a method for the isolation of vanadyl porphyrins from a mixture thereof with hydrocarbons and/or hetero hydrocarbons which method comprises the stages of (1) passing the mixture through a column packed with silica to effect a chromatographic concentration of the porphyrins, (2) passing the concentrate through a column packed with alumina to effect a further chromatographic concentration of the porphyrins, and (3) passing the second concentrate through a column packed with a product, derived from an inorganic oxide containing surface hydroxyl groups, containing groups of general formulae (I) and/or (II).

wherein R is a divalent radical containing up to 20 carbon atoms, Rl and R2 are halogen atoms, organic radicals containing up to 20 carbon atoms, or hydrolysis products thereof, M is metallic or hydrogen ion and (a) is an integer corresponding to the valency of M to effect a third chromatographic concentration.

Stages (1) and (2) follow conventional chromatographic practice and the mixture may be diluted in a sblvent, suitably an aromatic solvent, preferably toluene. The mixture is initially washed through the Certain of the chemical formula(e) appearing in the printed specification were submitted in formal form after the date of fiiing.

column using the diluent as eluent and the vanadyl porphyrin fraction is retained on the column. The latter may then be eluted by flushing with an eluent of increased polarity, e.g., an ester or halogenated hydrocarbon. The solvent is then removed to leave the vanadyl porphyrin fraction.

In Stage (1)the initial fractions contain saturated and aromatic components, leaving the desired por phyrins and resins in the later fractions.

In Stage (2) the initial fractions contain the resins and porphyrins and the residue remains.

In Stage (3) the concentrate is again dissolved in a diluent, suitably a blend of a paraffinic and an aromatic hydrocarbon. The column is washed through using the diluent as eluent but in this case, it is the initial fractions which contain the vanadyl por phyrins and which are concentrated by solvent removal.

Stage (1) should be carried out before Stage (2).

The separation will generally be carried out at ambient temperature.

Suitable sources of vanadyl porphyrins are crude oils and fractions thereof, particularly residue fractions. Venezuelan crude oils, particularly Boscan, are relatively rich in vanadyl porphyrins.

The invention is illustrated with reference to the following Example.

Example Stage 1 Initial Separation of VanadylMetallopor- phyrins on Silica Boscan crude (1.80 g, 3807 ppm VMP) was dissolved intoluene (10 ml) and placed onto a column (40x3.5 cm) of silica (200 g, 100-200 mesh). Toluene (250 ml) was added, and the column eluate monitored by visible adsorption spectroscopy for VMP's.

After 100 ml of toluene, the eluate became lighter in colour and VMP's started to come off the column.

This first 100 ml was collected as the first fraction.

Ethyl acetate (250 ml) was then added which brought a red band down the column. A further 250 ml of ethyl acetate was added to bring all the red material off the column, and this was collected as the second fraction. The solvent was removed from both fractions on a rotary evaporator under reduced pressure. The first fraction (1.50 g) contained 1820 clog of VMP )ca 25% of the VMP's, 1212 ppm). The second fraction (0.296 g) contained 5350 g of VMP's (ca 75% of the VMP's,18074 18074 ppm).

Stage 2 Further Concentration of Vanadyl Metalloporphyrins on Acidic Alumina The concentrate from the silica column (296 mg, 18074 ppm VPM) was dissolved in toluene (2 ml) and dropped onto a column (19x1 cm) of acidic alumina (15 g, 100-325 mesh). Toluene (100 ml) was added, followed by 10% chloroform in toluene. The latter brought a dark-red band down the column and this eluate was collected as one fraction. The solvent was removed on a rotary evaporator under reduced pressure to give a concentrate (78.6 mg) containing VMP's (4.94 mg, 57100 ppm). Thus, by conventional chromatography the VMP's are concentrated from 3807 ppm to 57100 ppm.

Stage 3 Final Purification of Vanadyl Metalloporphyrins on SulphonicAcid-Silica A portion of the VMP concentrate from the alumina column (17.8 mg, 57100 ppm) was dissolved in 1:1 n-heptane-toluene (2 ml) and dropped onto a column (19x1 cm) of sulphonic acid-silica (15 g). Further 1:1 n-heptane-toluene (50 ml) was added followed bytoluene (50 ml). Small fractions (ca 5 ml) were collected and monitored for VMP's by visible adsorption spectroscopy. The fractions containing metalloporphyrins were collected and the solvent removed on a rotary evaporator under reduced pressure. The material (ca 1 mg) contained 0.618 mg of VMP's (618000 ppm) and is ca 60% ofthe VMP's put onto the sulphonic acid-silica column. The final improvement in concentration is from 5.71% to 61 .8o/o with sulphonic acid-silica.

The sulphonic acid-silica was prepared as described in our co-pending application No.

35566/78.

Claims

1. A method for the isolation of vanadyl porphyrins from a mixture thereof with hydrocarbons and/or hetero hydrocarbons which method comprises the stages of (1) passing the mixture through a column packed with silica to effect a chromatographic concentration of the porphyrins, (2) passing the concentrate through a column packed with alumina to effect a further chromatographic concentration of the porphyrins, and (3) passing the second concentrate through a column packed with a product, derived from an inorganic oxide containing surface hydroxyl groups, containing groups of general formula (I)::

wherein R is a divalent radical containing up to 20 carbon atoms, R1 and R2 are halogen atoms, organic radicals containing up to 20 carbon atoms, or hydrolysis products thereof, M is metallic or hydrogen ion and (a) is an integer corresponding to the valency of M to effect a third chromatographic concentration.

2. A method for the isolation of vanadyl porphyrins from a mixture thereof with hydrocarbons and/or hetero hydrocarbons which method comprises the stages of (1) passing the mixture through a column packed with silica to effect a chromatographic concentration of the porphyrins, (2) passing the concentrate through a column packed with alumina to effect a further chromatographic concentration of the porphyrins, and (3) passing the second concentrate through a column packed with a product, derived from an inorganic oxide containing surface hydroxyl groups, containing groups of general formula (ill)::

wherein R is a divalent radical containing up to 20 carbon atoms, R' is a halogen, an organic radical containing up to 20 carbon atoms, or an hydrolysis product thereof, M is metallic or hydrogen ion and (a) is an integer corresponding to the valency of M to effect a third chromatographic concentration.

3. A method according to either of claims 1 or 2 wherein the mixture is diluted with an aromatic solvent prior to the first stage washed through the column with the diluent in the first stage, and eluted by flushing with an eluent of increased polarity.

4. A method according to any of the preceding claims wherein the mixture is diluted with an aromatic solvent prior to the second stage, washed through the column with the diluent in the second stage and eluted by flushing with an eluent of increased polarity.

5. A method according to any of the preceding claims wherein the mixture is diluted with a blend of a paraffinic and an aromatic solvent prior to the third stage and washed through the column with the diluent in the third stage.

6. A method as hereinbefore described with reference to the Example.

7. Vanadyl porphyrins wheneverisolated by a method according to any of the previous claims.