The present invention refers to a method for purification of liquid substances, especially petroleum and petroleum frac¬ tions from impurities of different kind, such as metals, metallic compounds, organic complexes etc.

At the refining of a crude oil there is obtained amounts of products corresponding to the boiling-point intervals of the oil, so called fractions, provided that no conversion pro¬ cess is made in the refinery. The demand for the heavier fractions is decreasing at the same time as the demand is increasing for lighter oil fractions such as petrol and diesel. Besides the demands for a low sulphur content be¬ comes more and more strict. The oil refineries all over the world meet this situation with an increased refinement of heavy fractions to light fractions and with an increased desulphurising.

Mineral oils contain metals, e.g. vanadium and nickel. The metals can on one hand be bound to big molecular complexes, so called asphaltenes and on the other hand to smaller molecules, e.g. naphtalenes. The size of the asphaltenes is in the interval 10A to 500A. Synthetic oils are produced from oilshale, oil sand or through direct liquidification of coal, peat, biomass, waste or other organic material also containing metals both natural or supplied in the manufac¬ turing process of the oil.

At present two different systems are used for actively reducing the total metal content in the oil. According to the first method the oil is mixed with a clay material at high temperature and the metals pass from the oil to the material.

According to the other method catalysts in high-pressure reactors of either trickelbed type or slurry form (ebulated bed). The pressure is kept high with hydrogen gas (between 50 and 200 bar) and the temperature between 300 and 450°C. There is a connection between high pressure and high temperature and the contrary, i.e. low pressure and low temperature within the given intervals. The manufacture of these catalysts is made through impregnation with salt solution, e.g. ammonium molybdate, of aluminium oxide with a large surface. After the impregnation the catalysts are dried and possibly calcinated at 400-500°C. A further imp¬ regnation can be done with e.g. cobalt nitrate. The impreg¬ nated material is dried and calcinated at 400-550°C.

The metallic compounds that are present in the above descri¬ bed oils detoriate the conversion of the heavier fractions to lighter fractions and the desulphurising of the heaviest fraction. These problems depend on that the sites of cata- lysts are poisoned by e.g. sodium or that the active compo¬ nents of the catalyst react with e.g. vanadium. This poiso¬ ning depends on the fact that vanadium forms compounds with rare earths metals which are present in catalysts, e.g. at the conversion process for catalytic cracking. Another important effect that the impurities have on the catalysts is that they fill the pores, so that reactants can not reach the active sites which are inside the pores.

There is also the disadvantage of too small pores so that molecules of asphtalene type can not get into the pores and react. When using small pores the pore filling problem also becomes troublesome. Other disadvantages with catalysts based on aluminium oxide are that they are expensive and the active and deposited metals become difficult to exploit and recover.

The object and most important features of the invention

The object of the present invention is to offer a method which in an effective and cheap way provides purification of liquid substances, especially petroleum and petroleum frac¬ tions from impurities such as metal, metallic compounds, organic complexes. This has been provided by the fact that the substance in question is brought in contact with a porous calcium silicate hydrate material in crushed form under such conditions with regard to contact time, tempera¬ ture etc. that an adsorption/absorption of the impurities in question to said calcium silicate hydrate material takes place, and that then the purified substance is separated from the solid calcium silicate hydrate material.

The method is not limited to petroleum but other applica¬ tions, e.g. in biotechnical separation technique, are also possible.

Description of the invention

The material that is used at the process according to the invention consists of porous calcium silicate hydrate material (CaO - Si0 ₂ - H ₂ 0) in finely divided form. One example is a material that is sold under the trade name Yxtender (R).

This material has previously been used as filler in organic materials such as plastic, rubber etc. see e.g. SE-B- 422.047.

At the production of this material a silica component is mixed with a calcium oxide component and various additives such as expanding agents, activators etc. The mixture is casted and heated under pressure and steam. At this steam hardening there will be a chemical reaction at which calcium silicate hydrate is formed and the mixture solidifies. The

chemical structure consists of silicate polymeric tober- morite crystals, i.e. crystals with a plate structure which are combined to micro cells. The above method of production is also called the hydrothermal process. The casted blocks are then crushed in desired fractions 0-5 mm. Through the hydrothermal method of production the material obtains a porous structure. It has now surprisingly proved that this material in an effective way has the ability to adsorb/ absorb various impurities, mainly heavy metals and tran- sition metals and big organic complexes, e.g. asphaltenes from petroleum and petroleum fractions under certain condi¬ tions. The pore size of the material is considerably bigger than for e.g. the above mentioned aluminium oxide catalysts.

The adsorption/ absorption material in question can be used directly without further treatment e.g. for adsorption/ absorption of heavy metals and coke forming organic comp¬ lexes in residue oils, so called heavy oils. It is herewith mixed with the oil, after which the mixture is allowed to react at a raised temperature, e.g. 300°C at which the residue oil liquidifies. After the reaction the liquid phase is separated from the solid phase.

An example of a converting process is that the oil is brought in contact with the finely divided material in a reactor, in which the lighter components are vaporized. Asphaltenes, metals and other impurities are deposited on the material. The oil vapours are quickly cooled as they exit from the reactor for minimizing thermal cracking of the obtained products. Such a process has been developed by Engelhard Corp. and is called the ART-process.

A further method of process is that the adsorption/ absorp¬ tion material that is in contact with a reducing gas, e.g. hydrogen gas at appropriate pressure and temperature.

There can also be added to the adsorption/ absorption mate-

rial substances which provide catalytic activity, e.g. active metals or their compounds from the groups VI, III and VIII in the periodic table, which increases the adsorption of vanadium and nickel. This admixture can take place either in connection with the mixture of the raw materials in the material or through impregnation of the finished material.

The process of manufacture for the adsorption/ absorption material can vary through the choice of metal component, expanding agent, activators so that a more active structure for the solid phase of the material and an open pore struc¬ ture is obtained. Usually Al is used as expanding agent in this type of material, however other substances mainly from the groups I, II, and III, which act as expanding agents, can be used for varying the pore size distribution and pro¬ vide an optimum activity.

Through the raised catalytic acvity of the adsorption/ab¬ sorption material the contact time and temperature for the reaction for the substance that is to be purified, e.g. oil, can be reduced compared to the untreated adsorption/absorp¬ tion material. The adsorption/absorption material can in this case be applied as a bed of particles of the material in granular size, at which the oil is brought to pass through said bed.

Other fields of application for the invention are inorganic filters for purification processes, adsorption agent for virus, separation material in biotechnique.

Description of embodiments

Example 1

Residue oil (Wilmington Crude with a boiling point exceeding 450°C) was heated to 300°C in inert nitrogen atmosphere. Finely ground calcium silicate hydrate with particle size

<20 μ was added under stirring, so that the obtained mix¬ ture consisted of 50% oil and 50% calcium silicate hydrate. The mixture was then allowed to react during two hours at the raised temperature. After the reaction the sample was cooled and extracted with a solvent (14% by weight of 2 - propanol and 86% by weight of decahydronaphtalene, C ₁₀ H ₁₈ ). The dissolved sample was centrifugated and analyzed with regard to nickel, vanadium and sodium by means of atomic absorption spectrometry.

In order to study the effect of metal adsorption at solvent extraction a number of experimental tests were performed, in which the oil sample was heated without admixture of calcium silicate hydrate. After heating calcium silicate hydrate was added and the procedure was then the same as above.

In order to make it possible to calculate the relative metal content in the residue oil after the reaction with calcium silicate hydrate material at 300°C compared to the metal content of the blind sample. The oil content of the test solution has to be determined. Two test solutions with different amounts of solvent have been used, in order to see if the amount of solvent had an effect on the metal content after the reaction.

The oil content in liquid phase= Oil in liquid phase/ Liquid

Sample weight - Solid phase after drying phase=

Solvent + Sample weight - Solid phase before drying

The relative metal content in the treated residue oil rela¬ tive to the blind sample can be calculated according to the following equation: Metal content in demetallized solution

Metal content in blind sample

AAS demet. sample/Oil content in demet. solution =

AAS blind sample/Oil content in dissolved blind sample

The result is shown in table I below.

Rel. Rel. vanadium sodium

0,53 0,46

1,00 1,00

Example 2

Calcium silicate hydrate with a sieve size of 0,25-0,71 mm impregnated with CoO and Mo0 ₃ was used for demetallizing of residue oil of the type Arabian light, Scanraff AB, and with the elementary content.

Substance molar % (excl. S)

C 38,79

H 60,98

N 0,10 0 0,14

S= 2,4% by weight

The vanadium and nickel content of the oil was determined by means of atomic absorption speetrometry and WW - jet fuel as solvent to 29 and 9 ppm resp.

Six different impregnated catalysts were used:

Table 2

The impregnation of the catalysts was made by adding an aqueous solution of the metal oxide and mixing it with the carrier material (calcium silicate hydrate), after which the material was dried. The dried material was calcinated in an oven at 500°C during 3 hours. After impregnating and cal¬ cinating one type of metallic compound one can continue with the following metallic compounds until one has prepared the material with all desired metallic compounds.

When the material was ready-prepared it was placed in a sulphuration plant, where the metal oxide is converted to sulphide. This sulphuration aims at making the metal more active in the demetallizing reaction.

For demetallizing the residue oil this was mixed with the catalyst material in a high-pressure reactor. The mixture was heated to the desired temperature and the reactor was filled with hydrogen gas to the desired pressure. The hydra- genation was continued for 3 hours.

The residue oil was analyzed with respect to the heavy metals vanadium and nickel by means of atomic absorption speetrometry.

In table 3 below the vanadium and nickel reduction in the residue oil is shown for different reaction conditions. The metal content is given in ppm vanadium and nickel in the oil before and after the demetallisation.

Table 3

The invention is of course not limited to the above examples but can be modified within the scope of the following claims.