DE1128941B - Multi-stage process for the production of a deacidified hydrocarbon oil - Google Patents

Description

Multi-stage process for the production of a deacidified hydrocarbon oil It is known to use hydrocarbon oil distillates for the purpose of removing mercaptans to refine by treating them with aqueous alkali, e.g. B. caustic soda, and then treated with an aqueous alkali hypochlorite solution. In some cases it will still followed by an aftertreatment with aqueous alkali.

For example, such a hypochlorite treatment can be carried out in several stages perform by adding a relatively concentrated hypochlorite solution to the final treatment stage supplies and the partially consumed liquor which settles in this stage in initiates the previous treatment stage, etc., up to the treatment solution it no longer contains active chlorine.

The mercaptan-containing hydrocarbon oil can also be treated with a countercurrent flow subject with a very dilute hypochlorite solution, with the fresh oil initially only comes into contact with the largely used up solution and only shortly before the removal is treated with the fresh hypochlorite liquor.

Depending on the conditions under which the refining is carried out will, e.g. B. depending on the alkalinity of the hypochlorite solution used, the Mercaptans in varying degrees to oil-soluble, non-corrosive sulfur-containing ones Compounds oxidized, e.g. B. to disulfides. Even when using one of the respective Mercaptan content equivalent amount of hypochlorite is often only in this way achieved incomplete oxidation of the mercaptans, and this experience has in in practice led to the fact that work was carried out with a considerable excess of hypochlorite is, for example, with seven times the amount of the theoretically required value. This additional consumption of the not entirely cheap hypochlorite is useful such a refining process is significantly impaired.

It has now been found that practically mercaptan-free and acid-free Hydrocarbon oil distillates by means of a carried out under special conditions Produce a two-step process with a much lower consumption of hypochlorite than before let: According to the invention, each of these stages comprises the successive action and separating an aqueous alkali or alkaline earth hypochlorite solution and aqueous Alkali solution on the distillate to be deacidified. The hypochlorite solution of the first Stage is used in a certain amount, which depends on the mercaptan content of the oil and between 0.5 and 2 times the theory calculated on the mercaptans contained in the distillate. The amount of hypochlorite of the second Process stage is in turn in a certain proportion to the amount of First stage oxidizer and the mercaptan content of the oil. According to the invention namely, so much hypochlorite is used in the second process stage that the Total amount that is used in the two stages together, between the 1.3- and 3 times the theory, calculated on the original in the relevant Mercaptans contained in distillate.

The alkali wash carried out at each stage is particularly challenging favorable influence with regard to a further decrease in the mercaptan content. In addition, other interfering acidic substances are also released from the treated hydrocarbon oil removed, e.g. B. formed approximately during the previous hypochlorite treatment Sulfenyl chlorides.

Referred to in the present description and claims the term "theoretical amount" that amount of hypochlorite solution that theoretically is required to remove the mercaptans contained in the hydrocarbon oil distillate according to the equation given below with reference to sodium salts is to oxidize to disulfides and water: 2 R S H -I- Na O Cl - @ R S S R -I- NaCl -I- H20 In this equation, the symbol R denotes a hydrocarbon residue.

In cases where the mercaptan sulfur content of the to be treated Hydrocarbon oil distillate is not known, the mercaptan content may be be determined by known methods, e.g. B. by an analytical statement the sulfur content of the oil in percent by weight. Since 1 mole of sulfur is 1 mole of mercaptan corresponds, the theoretically required amount of hypochlorite can then be directly Calculate from the analytically determined sulfur content of the oil distillate.

Before the hydrocarbon oil distillate in the first stage with the aqueous alkali or alkaline earth hypochlorite solution is treated, it can be a pretreatment with an aqueous solution of an alkali or alkaline earth metal hydroxide.

The concentration of the alkali or alkaline earth hypochlorite solutions, which be used in the two-stage treatment of the hydrocarbon oil distillate, can vary over a wide area; B. between 0.05 normal and 3, Be onormal with respect to hypochlorite. The aqueous hypochlorite solutions can contain other substances that promote the desired oxidation reactions, especially free alkali or alkaline earth hydroxide. Such hydroxides are in the Hypochlorite solutions preferably in amounts of 0.05 to 1.0 percent by weight. If the equipment used is made of metals such as mild steel, should the hypoctilorite solutions should be about 0.2 normal with respect to alkali hydroxide in order to avoid corrosion to prevent. The hypochlorite solutions used may also contain sodium chlorite be.

The hydrocarbon oil distillate and hypochlorite solutions are generally brought into intimate contact. The contact time can be vast Area fluctuate. The most favorable contact time is expedient by making a few preliminary experiments determined with the specially treated hydrocarbon oil. The temperature is in general between 0 and 50 ° C. This is generally achieved at room temperature highly satisfactory results.

The amount of hypochlorite solution mixed with the hydrocarbon oil distillate is brought into contact in the first stage, is preferably between the 0.8 and 1.6 times the theory, each calculated on the mercaptan content of the relevant Distillates.

After the used hypochlorite solution from that in the first stage treated oil separately, the oil treated with an aqueous caustic alkali solution and the used or partially used caustic alkali solution from the oil as well has been separated, the oil in the second stage is preferably with such Amount of an aqueous alkali or alkaline earth metal hypochlorite solution treated that the Total amount of hypochlorite associated with the hydrocarbon distillate in both Levels is brought into contact, between 1.4 and 2.4 times the value of theory lies.

The concentration of alkali hydroxide in those used for alkali washing Solutions can vary within a wide range. The solutions contain preferably 6 to 20 percent by weight alkali hydroxide; but they can be used until the alkali metal hydroxide contained therein is used up. The oil and the caustic solution are generally brought into intimate contact. The temperature used is generally between 0 and 50 ° C, for example room temperature is well suited. The caustic alkali solutions can also contain alkali mercaptides, which are either derived from aliphatic or aromatic mercaptans. It can turn out to be z. B. to be caustic alkali solutions that are used to extract mercaptans from a Hydrocarbon oil have been used. During the treatment of the hydrocarbon oil distillates compounds formed with hypochlorite and corrosive to metals, z. B. Sulfenyl and sulfonyl chlorides, react with such Alkahmercaptiden and become non-corrosive compounds, such as oil-soluble ones, even at room temperature Disulfides.

If desired, treatment of the hypochlorite treated Oils with caustic alkali are also practical in the presence of hydrogen sulfide free hydrocarbon oil are carried out, which contains mercaptans, so that mercaptides are formed in situ and bring about the desired reaction.

The hydrocarbon distillates obtained at each stage of the new process can be subjected to further treatments, e.g. B. a filtration or a Treatment with a solid absorbent or a wash with water before they are transferred to the next stage of treatment.

The partially used alkali hydroxide solutions can be in a possibly upstream washing treatment of further quantities of the starting material be used.

Light hydrocarbon oil distillates can be treated in accordance with the invention which contain mercaptans but are essentially free of hydrogen sulfide and have a final boiling point below 370 ° C, e.g. B. fuels for gasoline engines, Engines with compression ignition or for turbine engines and oils for heating or Lighting equipment.

The new process can be carried out batchwise or continuously will. A typical treatment facility is described below with reference to the schematic flow diagram briefly described. It will be a special embodiment of the method with reference to the treatment of acid gasoline with solutions of sodium hypochlorite and sodium hydroxide.

Acid gasoline is supplied via line A through mixing towers B in direct current out of line C with an aqueous solution of sodium hydroxide. The phase mixture is then passed into a settling vessel D. The settling aqueous layer, which contains partially used sodium hydroxide, is returned to the mixing towers B, while the gasoline phase is fed to the ball mixing valve E, where it is connected to a aqueous solution of sodium hypochlorite from line X is intimately mixed. This Phase mixture is passed into a settling vessel F, in which the used hypochlorite is separated and discharged via line G, while the treated gasoline together with aqueous sodium hydroxide solution from line L to a second ball mixing valve H is performed. Gasoline and aqueous sodium hydroxide solution are both in the mixing valve intimately mixed even as well as in the mixing towers J lying in the direction of flow. This mixture is then fed to a second liquor settling vessel K, in which is an aqueous, partly consumed from Sodium hydroxide solution Form existing layer and a gasoline layer. The aqueous layer is in the Mixing valve H is fed back through line L, and the gasoline layer becomes another Ball mixing valve M together with an aqueous solution of sodium hypochlorite the line Y is fed. The gasoline and sodium hypochlorite solution become intimate mixed and then fed to the second hypochlorite settling vessel N, in which the Phase separation takes place. The partially used hypochlorite solution is through Line P led to a hypochlorite mixing tank Q in which sodium hypochlorite solution is produced, which is to be implemented with further gasoline in the ball mixing valves E and M is suitable. A concentrated, e.g. B. 5, Onormal aqueous solution of sodium hypochlorite is also through line R together with fresh water from line S. the mixing tank Q supplied. Free alkali, e.g. B. sodium hydroxide solution, can by the line O can be introduced into the hypochlorite mixing tank Q.

The gasoline is drawn off from the second hypochlorite settling vessel N through line Y and mixed with acidic gasoline which flows in from the caustic settling vessel D through line T. The gasoline thus obtained is passed through line U into a collecting container W and there intimately mixed with an aqueous solution of sodium hydroxide. The completely deacidified gasoline is then separated from the aqueous layer, drawn off through line Z and can then be mixed and / or blended for use in internal combustion engines.

The hydrocarbon distillates deacidified by the new process after-treatments such as washing with water, filtering over solid adsorbents, reflux heating over lime or distillation, in particular if there are still undesirable oxidized sulfur-containing compounds of high molecular weight are included in the product.

Furthermore, the resulting distillate can be treated with additives which give the oil special properties, especially if the Distillates are intended to be used as fuels. For example, you can use the obtained distillates corrosion inhibitor, anti-knock agent, oxidation inhibitor, such as alkylphenols or aromatic amines, resin inhibitors, cleaning agents and coolants to add.

In the following examples is the mercaptan content of each hydrocarbon oil distillate expressed as the percentage by weight of sulfur, while the term "acid value" is the Number of milligrams of potassium hydroxide indicates which are required to make 1 g of the distillate to saponify and neutralize. Example 1.

Two acidic, directly distilled gasolines, two acidic naphthas and two Mixtures of acidic, direct distilled and acidic, thermally reformed gasoline, which all came mainly from Middle-East raw products, were with a Washed aqueous caustic soda solution until there is virtually no hydrogen sulfide and no longer contained free sulfur and those listed in Table I. Have properties. A sample of each acidic hydrocarbon oil so obtained was subjected to the following treatments in the order given: Treatment stage 1 (a) The acidic hydrocarbon oil was intimately mixed with the 1. O times the theory of a 0.1 N sodium hypochlorite solution, calculated on the mercaptan content of the sample.

The hydrocarbon layer and the aqueous layer were separated, and the spent sodium hypochlorite layer was discarded.

(b) The hydrocarbon oil was intimately mixed with sodium hydroxide solution.

The hydrocarbon oil layer and the aqueous caustic layer were separated and the latter layer was discarded. Treatment level 2 (c) The hydrocarbon oil was intimately mixed with 0.5 times the amount of Theory (calculated on the original mercaptan content of the sample) of a 0.1 N sodium hypochlorite solution.

The hydrocarbon oil and the aqueous layers were separated, and the aqueous sodium hypochlorite layer was discarded.

(d) The obtained hydrocarbon oil was 101 / o of its weight a 2.0 N sodium hydroxide solution.

Samples of the hydrocarbon oils obtained in each stage, were analyzed; the results obtained are shown in Table I below compiled.

The hydrocarbon oils obtained at the end were no longer acidic, although only 1.5 times the theory of hypochlorite solution was used in both treatment stages together. Table I. Sour oil, sour oil, Sour Oil, Sour Oil, Sour Oil, 1 Sour Oil, derived from derived from derived from derived from derived from derived from mixture of mixture of direct direct direct direct direct distilled distilled distilled distilled distilled distilled Gasoline Gasoline Naphtha Naphtha and and reformed reformed Petrol petrol ABCDEF Properties of Acid Carbon hydrogen oil before treatment: Specific weight at 60 / 60 ° C distillation ........ 0.648 0.644 0.7415 0.7415 0.7030 0.7030 (Table I, continued) Sour oil, sour oil, Sour oil, Sour oil Sour oil Sour oil, derived from derived from derived from derived from derived from mixture of mixture of direct direct directly directly directly directly distilled distilled directly distilled distilled distilled distilled and and Gasoline gasoline naphtha naphtha reformed reformed Petrol petrol ABCDEF Initial boiling point ..... 26 ° C 29 ° C 104 ° C 95.5 ° C 35 ° C 35 ° C 90 0% passed at. . 67 ° C 64 ° C 143 ° C 143 ° C 141 ° C 141 ° C Final boiling point ......... 99.5 ° C 100 ° C 160 ° C 160 ° C 170 ° C 170 ° C Mercaptan content ....... 0.029 0.029 0.025 0.026 0.020 0.023 Properties of the invention treated oils: a) After treatment with a theoretical amount 1.0 n-Na- trium hypochlorite solution Mercaptan content ....... 0.018 0.020 0.022 0.020 0.014 0.016 b) After separating the needed hypochlorite and 10 volume washing oil share 2 n caustic soda Mercaptan content ....... 0.0052 0.0042 0.013 0.013 0.0055 0.0064 c) After treatment with the 0.5 times the theoretical amount 0.10 n-sodium hypochlorite Mercaptan content ....... 0.0019 0.0014 0.011 0.010 0.0032 0.0046 d) Used hypochlorite separated, washed with oil 10 percent by volume 2 n-soda lye Mercaptan content ........ <0.0004 <0.0004 0.009 0.008 0.0014 0.0023 For comparison purposes, a further six samples of the acidic hydrocarbon oils A to F were subjected to a conventional refining treatment, that is, each oil was treated in a single stage with a solution of sodium hypochlorite containing sodium hydroxide, the solution being 0.10 normal with respect to sodium hypochlorite and with respect to the sodium hydroxide was 1.5 normal. The oil was then separated from the partially consumed treating solution and washed with aqueous sodium hydroxide solution. In each case, 4.5 times the theoretical amount of sodium hypochlorite was required to deacidify the hydrocarbon oils. Example 2 An acid gasoline mixture of directly distilled and thermally reformed gasoline (Middle East) was pretreated with an aqueous solution of caustic soda until it contained practically no hydrogen sulfide and no free sulfur, but only 0.028 percent by weight sulfur in the form of mercaptans. This oil was subjected to the treatments listed in Example 1, with the modification that 0.7 times the theoretical amount of sodium hypochlorite was used in treatment stage 2. The gasoline finally obtained gave a negative doctorate test. Example 3 An acidic mixture of partly directly distilled, partly thermally reformed gasoline (Middle East), which was subjected to a pretreatment with an aqueous sodium hydroxide solution until there was practically no free hydrogen sulfide and no free sulfur, but only 0.027 percent by weight sulfur in the form of mercaptans was treated in a plant which corresponded to the flow diagram explained above. The conditions in the individual treatment stages and certain properties of the products obtained in the various stages are given in Table II below. Table Il Flow rates in tons per day Total amount of acid gasoline .... 605 Through hypochlorite treatment vessels led acid gasoline .......... 525 Sour passed through secondary line T Petrol ......................... 80 0.101 n-sodium hypochlorite solution for Mixing valve E ................... 50 0.101 n-sodium hypochlorite solution for Mixing valve M .................. 50 Properties of the different treatment solutions Sodium hypochlorite solution for mixing valves E and M 0.101 n-Na O C1 hypochlorite in. Used solution from settling vessel F none Partially used hypochlorite solution from settling vessel N ........ 0.046n-NaOCI sodium hydroxide solution in settling vessel K ..... .... 4.0 n-NaOH sodium hydroxide solution in collecting container W .... 2.6n-NaOH Amount of sodium hypochlorite used, based on the original mecaptan content of the gasoline which flows through the hypochlorite treatment vessels. First treatment stage. . . 1, 14 times Second theoretical amount treatment stage ... 0,62fache theoretical amount Properties achieved on average different gasoline samples Mercaptan acidity salary From the settling vessel D to the front Run out laundry ... 0.027 - From sedimentation vessel F ........ 0.013 0.076 From settling vessel K ........ 0.007 0.001 From sedimentation vessel N ........ 0.003 0.051 From collecting container W to Wash with lye, before Blending with sour Gasoline from line T .... 0.002 0.033 From collecting container W to Blending with sour Gasoline and after washing with lye .....-.........- 0.0015 0.002 Thus, 1.76 times the theoretical amount of sodium hypochlorite, calculated on the mercaptan content of the gasoline actually treated with hypochlorite (525 tpd), or 1.53 times the theoretical amount, calculated on the mercaptan content of the total gasoline used (605 tpd), was required to achieve the To achieve the degree of refinement specified above.

For comparison purposes, a sample of the same gasoline was used subjected to a previous washing treatment with an aqueous sodium hydroxide solution and which contained 0.027 percent by weight sulfur in the form of mercaptans, the usual refining treatment as described in Example 1, subjected. However, this required 4.5 times the theoretical amount of sodium hypochlorite, to achieve the same level of refinement as above.

Example 4 An acid gasoline which contained 50% of a directly distilled gasoline and 50% of a thermally reformed gasoline, which predominantly originated from Middle East petroleum, was washed with an aqueous sodium hydroxide solution until there was practically no hydrogen sulfide and no free sulfur, but rather contained only 0.0242 percent by weight sulfur in the form of mercaptans. The gasoline was treated in a plant according to the flow diagram described. The sodium hypochlorite solutions used contained free sodium hydroxide in order to reduce the corrosion of the apparatus. The plant was operated for 24 days and the conditions in the individual treatment stages as well as certain properties of the products obtained in the various treatment stages are summarized in Table HI below. Table III Throughput speed in tons per day Total amount of acid gasoline .... 560 Due to the hypochlorite treatment vessels of led acid gasoline. .... 510 Sour passed through secondary line T Petrol ......................... 50 Hypochlorite solution for the first mixing valve E ........................ 40 Hypochlorite solution for the second mixing valve M ........................ 78 Characteristics of the different treatment solutions Strong sodium hypochlorite solution introduced into mixing tank Q .......... 5.25 n-Na OCl Sodium hypochlorite solutions introduced into mixing valves E and M ...... 0.106 n-Na O Cl -I- 0.162 n-Na OH hypochlorite in the used solution from settling vessel F ........ none Partly used hypochlorite solution from settling vessel N, fed through line P into mixing vessel Q 0.045 n-Na OCl sodium hydroxide solution in settling vessel K ..... ... 2.5 n-Na OH sodium hydroxide solution in the collecting container W ..... 2.0 n-NaOH Amount of sodium hypochlorite used, calculated on the original mercaptan content of the gasoline fed through the hypochlorite treatment vessels. First treatment stage .... 1.10 der Theory Second Stage of Treatment ... 1.23 of Theory Properties achieved on average different gasoline samples Mercaptan acidity Keep From settling vessel D to Wash with alkali. . 0.0242 - From sedimentation vessel F ........ 0.0082 0.010 From sedimentation vessel K ........ 0.0069 0.002 From the sedimentation vessel N ........ negative - Doctoral test From collecting container W to Blending with sour Petrol from secondary line T and after washing with lye. . 0.0013 0.002 So it was 2.33 times the theory of sodium hypochlorite, calculated on the mercaptan content of the gasoline actually treated with hypochlorite (510 tpd), or 2.12 times the theory, calculated on the mercaptan content of the total gasoline used (560 tpd), to achieve the specified level of refinement.

For comparison purposes, the same type of gasoline was used after a previous one Washed with aqueous sodium hydroxide solution subjected to the usual refining treatment (see example 1).

It was found that 4.7 times the theory of sodium hypochlorite, calculated on the mercaptan content (0.0242 percent by weight sulfur) of the total gasoline, was required to achieve the same level of refinement.

Claims (7)

PATENT CLAIMS: 1. Multi-step process for the production of a deacidified Hydrocarbon oil made from a mercaptane, but essentially no hydrogen sulfide containing hydrocarbon oil distillate using aqueous hypochlorite solution and aqueous caustic alkali solution, characterized in that the acidic hydrocarbon distillate is subjected to a two-stage treatment, each stage being the successive one Action and separation of an aqueous alkali or alkaline earth hypochlorite solution and aqueous caustic alkali solution and said hypochlorite solution in the first Level in amounts between 0.5 and 2 times theory, calculated on the in this distillate contained mercaptans, and in the second stage in such an amount that the total amount used in the two stages together is used is, between 1.3 and 3 times the theory, calculated on the original mercaptans contained in said distillate is. 2. The method according to claim 1, characterized in that the treatment of the distillate with aqueous hypochlorite solution in the first stage with 0.8 to 1.6 times the amount of theory, preferably with approximately the theoretical amount of hypochlorite is carried out. 3. Procedure according to Claim 1 or 2, characterized in that the treatment of the distillate with aqueous hypochlorite solution in the second stage with such an amount of hypochlorite is carried out that the total used in the first and second stages The amount is between 1.4 and 2.4 times theoretical. 4. Procedure after a of Claims 1 to 3, characterized in that sodium hypochlorite is used as the hypochlorite or calcium hypochlorite is used. 5. The method according to any one of claims 1 to 4, characterized in that the aqueous hypochlorite solution, which in the is used in the first or in the second stage, with respect to hypochlorite 0.05 normal to 3, is Ononnal. 6. The method according to any one of claims 1 to 5, characterized in that that the aqueous hypochlorite solution used in the first or in the second stage contains from 0.05 to 1.0 percent by weight of free alkali or alkaline earth hydroxide. 7. The method according to any one of claims 1 to 6, characterized in that one or more of the aqueous caustic alkali solutions used contain 6 to 20 percent by weight of alkali hydroxide. B. The method according to any one of claims 1 to 7, characterized in that all the treatment steps mentioned are carried out at temperatures between 0 and 50 ° C, preferably at room temperature. Considered publications: German Patent Nos. 578155, 944 513; USA: Patent Nos. 1627,338, 1552,830, 2,721,166; British Patent No. 184 281. Earlier Patents Considered: German Patent No. 957 591.