EP1142979A2 - Process for the deacification of acid petroleum destillates - Google Patents

Abstract

De-acidifying acidic crude oil distillates boiling in the region of 140-350 degrees C and having an acid number of 0.05 to more than 0.015 mg KOH/g comprises using an inorganic adsorbent.

Description

The invention relates to a process for deacidifying acidic petroleum distillates with a boiling range of 140 to 350 ° C and an acid number between 0.05 and> 0.015 mg KOH / g.

The process particularly concerns the deacidification of kerosene, from which Aircraft fuels such as Jet A 1 are produced. These aviation fuels are subject to certain specifications according to different standards such as DERD 2494 or ASTM D 1655, in which the Limit values for certain components of the fuel are set.

The critical parameters of these fuels are acidity and sulfur content and the content of mercaptans. These parameters are therefore in the specifications limited to certain limit values. The acidity of the distillates is mainly caused by carboxylic acids and phenolic compounds. These connections can, especially when using basic materials such as sodium hydroxide or similar substances meet, form salts or soaps that cause harmful effects in the fuel. So can salt crystals that are do not dissolve in the fuel, lead to clogging of the fuel filter. The soaps can bind small amounts of water, such as at low temperatures they can prevail at great heights, freeze out.

Sulfur contaminants in aircraft fuel can cause cadmium corrosion lead and especially organic sulfur compounds cause corrosion on the turbines.

The limits in the DERD 2494 specification for Jet A1 aircraft fuel are therefore 0.015 mg KOH / g in terms of acidity and in terms of Sulfur content at 0.3% by weight of total sulfur and 0.003% by weight of sulfur from mercaptan compounds.

Various processes are known from the prior art, these impurities to remove from petroleum distillates.

In conventional processes, the acidic petroleum distillate is produced in three different ways Steps. First, the acidity of the Distillates by washing them with basic solutions. there the acidic compounds are washed out of the distillate. It exists furthermore the possibility of filtering the distillates to find acids or phenolic compounds, which are then in solid form, to be deposited on the filter and so to clean the distillates. Corresponding methods are described in the US 3,398,086, US 4,033,860, US 4,121,999 and FR 23 92 103.

The mercaptan compounds are then removed in a second step. This are oxidized using metal phthalocyanine compounds on supports, Oxidizing agents and aqueous alkaline solutions implemented.

In a third step, the final treatment of the distillate takes place. there this is washed with water to remove the remaining alkaline compounds and to remove salts that have formed. This is followed by drying by passing through the distillate through a salt filter and decolorize the distillate by passing through a sound filter.

These processes are known to reduce the acid number of petroleum distillates also as "sweetening processes" or processes for sweetening petroleum fractions.

However, one disadvantage of these methods is the use of alkaline compounds. In most of the known methods Sweet basic solutions used in the first and second treatment step. It therefore occurs in the reaction with the organic acids in petroleum distillate to form e.g. Sodium salts that are found in the further processing of the distillate focus. These substances are catalyst poisons and therefore in the Further processing of petroleum distillates undesirable. In addition, one is also possible low content of alkali salts or other alkaline components in aviation gasoline aimed at the formation of disturbing described above To prevent salts or soaps.

Attempts have therefore been made to further develop the application of alkalis to be dispensed with as a neutralizing agent.

Newer methods of the prior art therefore essentially aim at this to avoid treatment with alkalis. For example, as a replacement used for the alkalis, aqueous ammonia solutions.

EP 0 474 545 B1 describes a process for sweetening petroleum distillates, in a single step in the absence of basic solutions the acidity levels aimed at for the sweetened distillates, mercaptan levels and color characteristics can be achieved. This will reduce the acidity and the mercaptan oxidation together in a single step carried out. The distillates are in the presence of an oxidizing agent, preferably a metal chelate passed over an oxidation catalyst. This Oxidation catalyst also contains pyrolyzed carbon and large ones Portions of mineral matrix with a degree of hydration of 1 - 20% by weight. In this process, the distillate is transferred only by transfer the oxidation catalyst neutralizes the acids and the phenolic compounds and oxidizes the mercaptans.

Since the process is water-free and there is no alkaline solution a later washing of the distillate with water is not necessary.

The disadvantage of this method, however, is that oxidation catalysts consisting of an absorbent solid impregnated with metal chelates Carriers are relatively expensive to manufacture and therefore such cleaning Manufacturing costs for aircraft fuels should increase significantly.

Hydrotreating processes as an alternative to sweetening processes for lowering the acid number have the disadvantage that this process is more expensive since, among other things, additional H _{2 is} consumed.

The technical object of the invention is a method for deacidifying to provide acidic petroleum distillates that are used more cost-effectively is carried out and also without the use of aqueous alkaline solutions can be.

This technical problem is solved by a method characterized in that is that deacidification takes place with an inorganic adsorbent. It is preferred to use low-sulfur distillates with a total sulfur content of <0.3% by weight (w / w) and a sulfur content from mercaptans of <0.003 wt% (w / w).

Preferred inorganic adsorbents are those selected from the Group predominantly silicon dioxide-containing adsorbents, predominantly aluminum oxide-containing Adsorbents and zeolitic molecular sieves or mixtures thereof used. The use of activated aluminum oxide is particularly preferred or silica gel.

These adsorbents preferably have a specific surface area of 100-1800 m ² / g, preferably 100-850 m ² / g and a micropore volume of 0.2-0.4 cm ³ / g. The method is used in particular for deacidifying kerosene, which are used for the production of aircraft fuels.

The process is preferably at temperatures of 30-150 ° C, preferably 45 - 120 ° C, a pressure of 1 - 20 bar, preferably 2 - 10 bar and a specific load on the column containing the adsorbent of 0.5-10 kg of petroleum distillate / kg adsorbent / h carried out.

The adsorbent is regenerated by thermal treatment with hot Gases at temperatures of 250 - 350 ° C or by washing with a polar organic solvents in any case where higher molecular weight Phenols are present as impurities in the petroleum distillate.

The process according to the invention is preferably carried out in two columns, that can be operated in parallel or in series. A pillar can be used in the meantime be taken out of operation for regeneration without the entire process must be interrupted.

These columns are filled with the inorganic adsorbents and then the petroleum distillate is passed through under the conditions mentioned above. In the absence of aqueous alkaline media and also in the absence of an oxidation catalyst without further after-treatment acid numbers reached, which are <0.015 mg KOH / g. The phenolic compounds and others Acids, as well as parts of the mercaptans containing are bound to the adsorbent. Since no aqueous alkaline solution is used, there is also a downstream one Washing and final cleaning step is not necessary.

Low-sulfur petroleum distillates are preferably used for the process because here the mercaptan concentrations are already close to the required specifications lie. Such low-sulfur petroleum distillates can be made using appropriate Crude oils or by mixing low-sulfur distillates with sulfur-rich distillates can be produced with little effort.

This allows the more expensive oxidation process to remove the mercaptan compounds be avoided and still a petroleum distillate with sufficient Quality with regard to acidity and sulfur content can be obtained, which the required Specification values met.

Around 1800 - 2200 t of petroleum distillate per ton of adsorbent are added per cycle. After that, regeneration is generally necessary. This is done by treatment with chemical gases at temperatures of 250 - 350 ° C, preferably with nitrogen or methane. Sufficient regeneration is generally achieved by this measure. If higher amounts of higher molecular weight phenols are present in the petroleum distillates, it may be necessary to additionally elute with a polar solvent. Alternatively, it is also possible to trap the higher molecular weight phenols before the actual adsorbent bed, for example by means of a so-called guard bed, in order to prevent these compounds from penetrating into the reactor. For this purpose, adsorbents are used which are particularly suitable for higher molecular weight compounds. Aluminum oxides which have a porosity> 50 nm of at least 0.15 cm ³ / g are particularly suitable.

Figure 1 shows experimental results of deacidification of straight run kerosene with an adsorbent based on Al ₂ O _3, for example Alcoa CDX. The acid numbers of the kerosene used were between 0.02 and 0.04 mg KOH / g. After deacidification, acid numbers were achieved which are in the range 0.002-0.015 mg KOH / g.

These results are even after an application of 1,700 - 1,800 t Distillate per tonne of adsorbent reached.

Fig. 2 shows the possible different operating modes for the adsorption and Desorption processes in the columns. The number 1 denotes the feed of the distillates from the top column, number 2 the flow of the distillates after deacidification. The number 3 denotes the inlet of the regeneration gas and the number 4 the flow of the regeneration gas. With the number 5 is the inlet of a polar Desorbent denotes and with the number 6 the process of desorbent. Number 7 denotes the columns, number 8 the top column and number 9 the pool.

The columns 7 can be operated in different operating modes. So can both columns 7 are operated in a parallel operating mode. Then it will be the adsorption was carried out simultaneously on both reactors. The distillates are then led from the top column via the feed 1 into the reactors 7, where the adsorption is carried out. The products are over the drain 2 in the pool 9 collected. Alternatively, the columns can also be connected in series.

A second alternative operating mode provides that one of the reactors regenerates is, while the adsorption takes place in the other reactor. During desorption z. B. the polar liquid desorbent preferably via the inlet 5 of led through the column above. Desorption of that in the column takes place Adsorbent, after which the desorbent is removed via the outlet 6.

An organic solvent can be used as polar desorbent. The column is then flushed dry with hot gas from below. The other The column continues to operate in the adsorption mode. Alternatively, the regeneration process instead of using a polar liquid desorbent as thermal regeneration of the adsorbent can be carried out at temperatures of 250 - 350 ° C. Hot nitrogen or hot methane is fed in from below via feed 3 passed through the reactor.

Fig. 3 shows the reduction of the acid number in medium oil with fresh adsorbent and Adsorbent after desorption with methanol.

With the method according to the invention, deacidification is possible at low cost of petroleum distillates with a boiling range of 140 - 350 ° C. In this case, the jet A 1 for aircraft fuels are produced in a simple manner necessary specifications achieved without the need for several procedural steps are and without using alkaline aqueous solutions. Farther can also occur completely when using low-sulfur petroleum distillates the oxidation of mercaptans can be dispensed with.

Claims (9)

Process for deacidifying acidic petroleum distillates with a boiling range of 140 to 350 ° C and an acid number between 0.05 and> 0.015 mg KOH / g, characterized in that the deacidification is carried out with an inorganic adsorbent. Process according to Claim 1, characterized in that low-sulfur petroleum distillates with a total sulfur content of ≤ 0.3% by weight (w / w) and a sulfur content from mercaptans of ≤ 0.003% by weight (w / w) are used. Process according to Claim 1 or 2, characterized in that adsorbents selected from the group consisting predominantly of silicon dioxide-containing adsorbents, predominantly aluminum oxide-containing adsorbents, zeolitic molecular sieves and carbon-containing adsorbents or mixtures thereof are used. Process according to one of claims 1 to 3, characterized in that activated aluminum oxide, silica gels or zeolitic molecular sieves are used as the adsorbent. Method according to claim 3 or 4, characterized in that the specific surface area of the adsorbents is 100 - 1800 m ² / g and the micropore volume is 0.2 - 0.4 cm ³ / g. Method according to one of claims 1 to 5, characterized in that kerosene are used as petroleum distillates. Process according to one of claims 1 to 6, characterized in that the process is carried out at temperatures of 30-150 ° C, a pressure of 1-20 bar and a specific load of 0.5-10 kg of petroleum distillate per kg of adsorbent per hour . Process according to one of claims 1 to 7, characterized in that the adsorbent is regenerated thermally at temperatures of 250-350 ° C. Process according to one of Claims 1 to 7, characterized in that the adsorbent is regenerated by washing with a polar organic solvent.

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