DE1645724A1 - Desulfurization process for heavy petroleum fractions - Google Patents

Description

DR. EULE DR. BERG DIPL.-ING. STAPF

PATENTANWÄLTE 8 MÜNCHEN 2. H ILBLESTRASSE 2O

Dr. Owl dr Berg Dipl.-Ing. Stopf, 8 Munich 2, HilblestrgBe 20

Our sign

date

6. Pebr. I967

Attorney file 14 848

Esso Research and Engineering Company Elizabeth, New Jersey / U. S. A.

"Desulfurization process for heavy petroleum fractions"

The present invention relates to an improved method for removing sulfur, nitrogen shark

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term and metallic impurities from petroleum fractions such. B. heating oil, shale oil, residues, as well as reduced or untreated crude oil. In particular, the present invention addresses the use of molten alkali metal hydroxide, with 5 -. 3o% by weight of water based on the Gesamtreagenz, for the removal of sulfur and nitrogen-containing and metallic impurities from heavy petroleum fractions. More particularly, the invention relates to a more efficient removal of the contaminants from hydrocarbon fractions by multi-stage treatment of the input feed and by multi-step treatment of both the input feed and the molten alkali hydroxide reactant participating in the reaction.

In general, sulfur occurs in petroleum in one of the following forms: as mercaptans, sulfides, disulfides, and as part a substituted ring, of which thiophene is a prototype. The mercaptans are usually found in the low boiling point Fractions encountered e.g. B. in light petrol, kerosene and light gas oil. Numerous procedures for removing the Sulfur from these low-boiling fractions have been suggested such as e.g. B. the doctoral process for sweetening (where the Mercaptans are converted into sulfides), alkaline treatment, solvent extraction, copper chloride treatment,

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_ 3 -

etc., being a more or less satisfactory Decrease in sulfur or inactivation of mercaptans is obtained by converting them into disulfides. if if the latter method is used, the disulfides will generally remain in the product so treated and, if a sulfur-free product is desired, must be removed by another process step.

The removal of the sulfur from higher boiling fractions, however, poses more difficulties. Here the sulfur is for the most part in the less reactive forms of sulfides, disulfides and as part of ring compounds such as e.g. B. thiophene present. Such sulfur is of course not amenable to chemical operations sufficient to remove mercaptans. The use of extraction processes from sulfur-selective solvents are also unsatisfactory because the high-boiling petroleum fractions have too high a percentage of sulfur-containing molecules. If z. For example, if a residue contains only about 3 % sulfur, it is estimated that essentially all of the molecules may contain sulfur. Therefore, if such a residue is extracted with a solvent selective for sulfur compounds, most of the residue would be lost as an extract. Metallic impurities such as B. nickel and vanadium compounds

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are found as constituents in practically all crude oils. These contaminants bring about another problem. After the fractional distillation of the crude oils, these metallic impurities are concentrated in the residues, which normally have an initial boiling point of approximately 538 ^{° C.} Such residues are commonly used as heavy fuel oils, but the metallic impurities contained therein have been found to damage incinerators in which these residues are incinerated contrary to the norm. These contaminants not only result in ash, which leads to silting and the formation of deposits on the boiler tubes, the walls of the combustion chamber and the gas turbine blades, but they also attack the refractory materials that are used to line the boiler and combustion chamber and they corrode the Boiler tubes and other metallic surfaces with which they come into contact at high temperatures.

In the past, chemical methods of removing the sulfur have therefore been ineffective for removing large amounts of sulfur and more, they showed little or no effect on the nitrogenous od / metallic impurities as these

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other procedures needed to remove it.

It is already known that sulfur compounds and other impurities from various crude oils and Hydrocarbon fractions by bringing the fractions into contact with a content of sulfur or impurities, can be effectively removed with molten alkali metal hydroxide. However, it has been found that the this way removable proportion of sulfur is limited. That means the amount of sulfur that is effectively made up a single fraction can be removed is limited. An increase in the amount of contact with the individual Alkali metal hydroxide brought to the sulfur-containing fraction over about 100% by weight gave no significant improvement in terms of sulfur removal. To some extent, however, the concentration of in Contact with the input materials of the alkali metal reagents and the contact time, the extent to which sulfur is removed .

It has also been found that temperatures within a specific range have an effect, i.e. as the temperature rises, so does the amount of sulfur removed. Furthermore, the residence time was also or the time the sulfur-containing fraction was in contact with the molten alkali metal reagent, up to 4 hours up significant; over a period of 4-6 hours

009829/1273. - 6 -

in addition, the amount of sulfur removal does not noticeably increase. Although sulfur removal was relatively effective in a one-shot process and the percentage of sulfur removed varied somewhat with the particular crude fraction treated, it was found that the molten alkali metal reagent, no matter the amount used, was prolonged under the extreme conditions Residence time did not exceed a removed sulfur limit of about £ 5 % of the sulfur present in a single treated oil. This occurred despite the use of a large excess of alkali metal reagents and the use of elevated temperatures and extended contact time.

This method of removing sulfur and other impurities from fractions containing impurities, generally, although effective, does not achieve beneficial utilization of the alkali metal hydroxide reagent, and Good sulfur removal requires long treatment times.

It has now been found that impurities by contacting the petroleum fraction with molten alkali metal hydroxide which comprises about 5 -. Containing 3o% water by weight, based on the Gesamtreagenz, at temperature conditions within

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half the range of about 2O4 - 427 ° C may be removed _r if one carries out the reaction in two or more stages.

It was previously considered that the limitations on sulfur removal with molten potassium hydroxide is due to the character or structure of the individual sulfur-containing hydrocarbons. That is, that when an oil with a particular type or types of compounds with molten potassium hydroxide is released of sulfur from this type of compound has reacted no further sulfur in this charge Compounds can be reacted to remove further sulfur. That view was supported by the fact confirms that as the ratio of z. B. molten potassium hydroxide for charging, the curve, which represents the sulfur removal, flattens and thus indicates that all compounds suitable for conversion have already reacted with the potassium hydroxide.

Also after adding excess amounts of the alkali reagent beyond the stoichiometric amount rose the desulfurization reaction did not noticeably occur and it was believed that the reaction did not go through equilibrium is restricted.

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Unexpectedly, the applicant found that a substantial further increase in sulfur removal could be obtained if, for the same total dosage over the same contact time, desulfurization was carried out in two or more stages, with shorter contact times, and with the same total amount of potassium hydroxide, and with the same Total contact time and thus a substantial increase in the total sulfur removal achieved with the same total amount of potassium hydroxide and with the same contact time. It was like that B. possible to remove up to 75% of the sulfur from a Kuwait vacuum residue using two batch treatments with 50 % potassium hydroxide on the oil, each lasting one hour, while a single treatment with 100 % potassium hydroxide on the oil takes 2 hours Duration reduces the sulfur content by only about 52 %. The applicant also found that a competing reaction also takes place during the KOH desulfurization, with potassium carbonate being formed at the same time as potassium sulfide. The potassium carbonate does not take part in the desulfurization reaction. The formation of potassium carbonate can essentially lead to an increase in the amount of KOH required to carry out the desulfurization reaction.

A good desulfurization can be achieved. However, at temperatures above 399, some feeds will

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the alkali applied uselessly and preferentially converted to potassium carbonate rather than potassium sulfide.

Applicants have found that the above limitations in sulfur removal have been overcome and used more effectively of potassium hydroxide can be obtained by contacting potassium hydroxide, and charging performs in more than one stage. It is natural to use a staged procedure in solvent extractions not new; however, the increase is in the utilization of potassium hydroxide and the increase is in sulfur removal by molten alkali metal hydroxide by a step process completely unexpected. The applicant also found Surprisingly, that in the following stages the same degree of desulfurization with less severe treatment or Temperature and / or time can be obtained as in the previous step, with a substantial decrease gaseous Prpdukten is achieved. Carrying out the subsequent stage operations at lower temperatures and treatment times thus results in a substantial reduction in product degradation.

To achieve a good contact between the Alkalimetallhydroxydreagenz and the hydrocarbon in the treatment to remove impurities, it is necessary to mix the reactants carefully, with

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emulsification frequently occurs. It was found that this emulsion was difficult to break, so that even with good desulfurization and removal of other contaminants, the difficulty in breaking the emulsion into a partially spent "reagent layer and a desulfurized oil layer made the process inefficient The applicant found that an effective separation of the inorganic and oil products could be achieved by washing the product mixture with about 50-200 percent by volume of water at temperatures above ITJ ⁰ C. It was found that washing at temperatures above 177 ^° C., for example with an amount of water equal to the molten alkali metal reagent, was sufficient to separate almost the entire amount of inorganic material in the form of a clear aqueous solution that could easily be separated from the desulfurized oil layer.

Depending on the treatment temperature during the desulfurization reaction and it may be desirable to add a light diluent to the individual feeds being treated add to the reaction mixture in order to obtain a viscosity reduction of the oil before the water washing stage, which is useful for a good separation of oil and inorganic material. For some loads it is desirable the water washing stage at temperatures as high as

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3l6 - 371 ° C to perform organic carbonic acid salts to destroy that occurs during the desulfurization reaction may have formed. These organic carbonic acid salts contribute to the formation of the emulsion. A bleaching earth filtration stage can be used to remove all but less than residual amounts of alkali in the desulfurized oil 5 ppm alkali can be used with advantage.

FIG. 1 is a flow diagram of an embodiment of FIG Invention, in which the oil in three Stages brought into contact with molten alkali metal hydroxide and the spent molten hydroxide subsequently regenerated and heated to remove the excess water and then circulated.

Figures 2, 3 and 4 are graphic explanations showing the effectiveness of a multi-stage treatment of a hydrocarbon fraction show for removal of sulfur. These graphical explanations also show the Sulfur removal as a function of weight ratio of potassium hydroxide to the input material in various Treatment temperatures.

Fig. 5 of the drawings shows the decisive influence the temperature on the clarification and separation of the inorganic alkali metal hydroxide reagent from the desulfurized oil fraction.

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Pig. 6 is a flow diagram of a three step process at which the feed is passed through the units in countercurrent to the treatment agent.

When carrying out the method according to the invention in In accordance with the applicant's procedure, with the charging in two or more stages and / or the Reagent is fed in two or more stages, there will be a substantial increase in the utilization of the alkali metal hydroxide reagent and achieved a substantial increase in the amount of removable sulfur. By the possibility the better utilization of the alkali metal hydroxide reagent there is also a substantial reduction in the amount of reagent required to carry out a specific desulfurization of a certain height is required for a single load; it also continues to limit the requirements on pumps, distillation capacity for removing excess water from the separated alkali metal reagent, as well as regeneration capacity for the regeneration of the alkali metal reagent. All of these advantages add up to one considerable savings in investments in apparatus, reagents and process costs.

Referring to Figure 1, a charge of 510 ⁰ C + Kuwait residue is obtained from a suitable source .

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and added via line 4 to contaminant removal zone 1 where it is contacted with a molten alkali metal hydroxide having 5-30 weight percent water based on the total amount of reagent entering via line 29. The residue and the molten alkali metal hydroxide are intimately mixed, whereby the sulfur are caused metallic and nitrogen-containing impurities in the residue with the molten alkali metal hydroxide to form product which λ from the hydrocarbon oil with the partially spent reagent solution are removed, thereby giving a high quality product . Although the impurity removal zone 1, as shown in the drawing, represents a batch-wise stage, the implementation of this process on a continuous basis is also to be understood by it.

The amount of water in the molten alkali metal hydroxide is important to the improved results of the present invention. The water content should be within the range of about 5-30 percent by weight, based on the total amount of reagent, preferably 7 to 25 percent by weight and especially 10 to 20 percent by weight. The most preferred water content is about 15 percent by weight, based on the molten alkali metal hydroxide or KOII. 1/2 H _? 0. The temperature conditions during the

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Contact stage should preferably be within the range of 204 • 427 ⁰ C ₃₂₃₂ - amount to 399 ° C and particularly 260 371 ⁰ C. The amount of molten alkali metal hydroxide reagent (including water) used in that step can be within the range of 10% by weight of the treated feed, more generally within 25-100% by weight, preferably within 25-50% by weight. This should be understood to mean that, depending on the proportion of sulfur present and the amount of reagent used, the reagent is still suitable for use in the treatment of additional oil before regeneration is required. In general, these ratios show an excess of reagent over the proportion which has actually reacted with the sulfur, so that finally part of the reagent separated from the treated oil can be circulated directly to a treatment zone. The duration of treatment varies from 1/10 hour to 16 hours, with the longer the contact time, the greater the proportion of impurities removed. In general, treatment times within the range from half an hour to 6 hours are used. The preferred treatment time per stage is from about half an hour to about 2 hours.

p
feed varies from 0-35 kg / cm, and is not critical to the desulfurization reaction.

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The mixture of alkali metal hydroxide and hydrocarbon material exits contaminant removal zone 1 through line 11 and is mixed with about 0.25 to 2.0 volumes of water / volume of the reaction mixture introduced through lines 25 and 31a is passed through settling zone 5 Mixing maintained at a temperature above about 177 ° C. The water separates as a clearly distinguishable phase from the treated residue phase. The water layer containing the reaction products of a cleaning impurities and the molten alkali metal hydroxide.

The molten alkali metal hydroxide phase from the settling zone is passed via lines 18 and 21 to the regeneration zone 9 for circulation. The partially desulfurized oil is removed from the settling tank 5, taken off via the top line 12 and transferred to the second reaction stage, zone 2 _; introduced, in which it is intimately mixed with fresh or regenerated liquor introduced through line 30 . After a suitable treatment time, it is removed through line 13 and introduced into the settling tank 6. Prior to introduction into the sedimentation tank 6, it is mixed with about an equal part of water and cooled to a temperature above about 177 ⁰ C half. In the settling tank 6, the mixture quickly settles into an anhydrous oil layer and an aqueous layer that contains the inorganic impurities. The aqueous layer with the contained alkali metal hydroxide and the removed inorganic

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- - '. ■■■■ - "■.. - 15 ·

4 (ρ

Impurities are withdrawn through line 19. The oil, which in turn has been reduced in sulfur content by about 50% of the sulfur content, is introduced in stage 2, drawn off via the top line Ik and introduced into the third stage of the reaction in zone 3. In zone 3 it is mixed with fresh or regenerated alkali which is introduced through line 31 and this mixture is given an opportunity to react for a suitable period of time. The reaction products are withdrawn through line 15 and mixed with washing water introduced through line 26 and introduced into the settling tank 7, in which they are in turn separated into an aqueous inorganic layer and an anhydrous oil layer. The anhydrous oil layer is drawn off overhead through line 16 and introduced into the water tank 8, where it is subjected to a water wash of water introduced through line 30a in order to remove any remaining amount of alkali, no matter how small. The desulfated oil, which has lost $ 75 or more of its sulfur content, is withdrawn overhead through line 17 and stored. The aqueous layer is withdrawn from the settling tank 8 and appropriately mixed with circuit washing water from line 33 and then passed through line 25 as washing water to the settling tanks 5, 6 and 7 through lines 25, 31a, 27 and 26. The inorganic aqueous layer from the settling tanks 5, 6 and 7 is withdrawn through the lines 18, 19 and and combined in the collecting line 21 and on

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returned to the regeneration zone 9> in which the used and / or partially used molten alkali metal hydroxide is regenerated in the regeneration zone 9 by suitable, well-known regeneration agents. The regenerated alkaline solution is withdrawn through line 22 and is distilled in the distillation zone 10, reconcentrated to the entire, introduced in the various relocation operations the wash water at the top to be removed, and so that the molten Alkalimetallhydroxydreagenz a water Λ concentration of between about 5 to 30 % Has water. Depending on the type of reaction, the excess wash water can be removed first. Fresh lye can be added through line 2k . The regenerated liquor, re-concentrated by the removal of water, and the fresh liquor are then fed into reactors 1, 2 or 3 via lines 23, 28 and 29, 30 and 31. The distilled water from the distillation zone 10 goes overhead through line 33, fresh water can be added through line 32 as required and is passed through line 25 to supplement the washing water in each of the three settling tanks 5, 6 and 7.

The settling zones 5, 6 and 7 are at a temperature approximately maintained above 177 ° C up to the temperatures in contamination removal zones 1, 2 and 3 to the to facilitate heavy separation of the oil and reagent, and to avoid heat losses from the alkaline feed

009829/1273 -I ₇ -

Af

Avoid regeneration zone 9. Various common items of equipment, which in the embodiment of the invention can be used according to Fig. 1, e.g. pumps, heat exchangers, ovens, contact devices, etc. were made omitted for the sake of simplicity of the drawing. The omitted equipment will be stored in one, for a professional known type, used and is not part of the invention and therefore not shown in the drawing.

The dosing rate of fresh and / or regenerated liquor at each stage can be varied until the optimum rate of potassium hydroxide utilization for each of the subsequent stages is determined or the same dosage rate as in the first stage can be maintained for each as each unreacted excess potassium hydroxide from the subsequent ones Stages that do not react to the removal of sulfur, are only driven in a circle and regenerated. However is the determination of an optimal dosage rate is advantageous, since later the load on each of the three sedimentation vessels and decreases at the distillation column, and since later that required for a good separation under specific separation conditions Percentage of water with the dosage rate of alkali brought into contact with the feed to be desulfurized increases. The entire process can be carried out as a continuous or batch process.

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Pig. 1 is a schematic of an effective stage feed with fresh reagent in each stage; however, both staged feeding and a staged process can be used with reagent feed in an apparatus similar to that in Pig. I illustrated can be obtained by making several Performs process variations.

For example, with regard to FIG. 6, the entire Irish reagent fed through line 104 to the last stage, zone 103, of the reactors and with one to desulphurising material are brought into contact, which is already reduced mainly in the sulfur content by the effect of the previous step treatments in zones 101 and 102. The reaction mixture from zone 103 goes through lines 105 and 107 to the settling tank 106. Water from line 108 and / or line 109 is to be added in approximately equal proportions and then left to settle the mixture. The desulfurized oil is removed through line 110 and conveyed into the settling vessel 111. The oil is added through line 112 with water. The product oil is removed through line 113, the wash water, which contains a small amount of alkali is removed through line II4. The alkali can come from this water be recovered upon request. Dilute, partially used alkali solution is drained from the settling vessel 106 Line 115 removed and taken to distillation zone 116.

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The distillation is carried out under suitable conditions for the Concentrate the reagent to about 5 to 30 percent by weight Water carried out. The re-concentrated alkali is passed through line 117 to zone 102, where it is with partially desulfurized oil fed to the reactor from line 118 is reacted. The reaction mixture from zone 102 goes through lines 119 and 120 to settling vessel 121. Water from line 122 and / or 123 is approximately the same amount is added and the mixture is allowed to settle. The partially desulfurized oil goes through Line 124 to zone 103. Dilute, partially used alkali solution is discharged from the settling vessel 121 through line Removed and goes into distillation zone 126. Partially used, re-concentrated alkali solution goes through Line 127 to zone 101 where it is reacted with fresh feed entering the reactor through line 128 will.

The reaction mixture from zone 101 passes through the line

129 and 130 in the sedimentation vessel 131. Water is from pipe

130 and / or line 132 is added in approximately the same amount to the mixture and the mixture is allowed to settle. Dilute, partially used alkali solution is removed from the settling vessel 131 through line 133 and passed to the distillation zone lj> k . Used alkali solution goes through line 135 to regenerator 136. The used

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Alkali metal hydroxide solution is made using suitable regeneration aids regenerated. The regenerated caustic solution goes through line 137 to distillation zone 138. In this zone fresh alkali solution is added through line 139 and the water content of the alkali solution is adjusted to a concentration of 5 to 30 percent by weight set. The alkali solution is introduced into zone 103 through line 104 and another Countercurrent contact sequence is carried out. Under a counter-current contact it is understood that the alkali flows from right to left through the process units of Figure 6 and the feed flows from left to right while intimately touching the alkali, which is moving in the opposite direction. The reaction and the separate process conditions, which include both feed and reagent stage processes, are similar to those mentioned earlier. However, the temperature as well as the contact time in each of the reaction zones after the Contact in the first zone will be less.

This working method attracts both one-step procedures in the With regard to the charge as well as the reagent. The fresh reagent is loaded with the lowest sulfur concentration and the most used and partially consumed alkali is with the feed brought into contact with the highest sulfur content. This procedure allows a considerable amount of Degree of flexibility in the alkali dosage ratio and good overall utilization of the alkali.

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• The following examples are intended to illustrate the various application forms explain the present invention:

Example 1:

Batch tests were carried out at 510 ^° C. with Kuwait residue containing 5.2 percent by weight sulfur, with molten water-containing potassium hydroxide, in order to determine the influence of the variation in the amount of potassium hydroxide, its water content, the temperature conditions and the treatment time. The individual experiments were carried out by adding the indicated amount of potassium hydroxide to the oil at 149-2O4 ° C. with stirring, allowing the temperature to rise to the predetermined level and holding it for the prescribed time with continuous mechanical stirring at high speed. After cooling to approximately 121-149 ° C, sylol or other comparable hydrocarbons were added to allow the oil to separate from potassium hydroxide and to remove the diluent from the treated product by distillation. In some examples where potassium sulfide was left suspended in the oil, the sulfide was decomposed with acid prior to removal of the sylol. The results are given in Table 1 below:

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·· '■:' TABLE I '; -. ·

".." '■' - ■ · Influence of the process conditions on the desulfurization; '"" "'.

O "η / and demetallization with molten KOH-H ₀ O mixture. - ^: - - ^ ϊ." - ίί "'-Skf&S'

r * ^{: r} ■ ■ ' ^v '" Classification procedure ■" · ".. -

ifMfhsX'et '*' ^ weight ;? KOH '"" Temperature Treatment ""! "· '.%' ■. '" Λ Jf "^ V- " - "■ ΥΓΐ-"" In KOH-HoÖ-Mlschixng ^? In the" Charging In ^c C in hours '" DesuUnMerttog - 5 removed " - ■' ·.

——— —-—-—-—. "! .-» - Γ Influence of the amount of KOH-HpO mixture - "-" "'

- 15 ... 200. .316.

Influence of the water content of the ge -. »-. melted KOH · '■

-. 100 288. 4 31 100

15s ·. \ ^r:: - J ^> j; ..: 100 - ■: ■■■ 3IS -;....? . > - 4 ■; - ~ .. _r .47 :. _{/ Ä} . . 100 15 "'■'■■" · ■■. 100 343 '3.3 64 100

Influence of the treatment time

2 "1 100 -ty 4 10 - * ^ j ^

1.-7 '- "- V-'-" - ""'100 - · ■ - ■''·"■ - itS *""-*'"'- : - r 23 60 X y \

15 "100 3i6 4 '47 100 ⁰⁹ X **>

_f 3l6 ":.:: .. * · ■. *: ■. 31 -".. 55 "- ^

Influence of temperature '-

I ..;. ... "^ 4-5- ^ - ^ -". · -.- .. 100 .. | 3i6 -1 - - 28. .. .. · -: -.- ■.: · ■ ··. ■■ "Vi" - ^ Ί5 ¹ """^*".'■■■"V·".' ■■ '.' -1Ö0 - "'-' ■ ^! 3l6 4:. 47 '. ■.' - . '■ · 15 100 316 16"60'.' ^: · -

■ '' CD

(l) These data illustrate the water retention characteristics of KOH at various temperatures, "^

since little or no water was lost from the molten reagent during treatment. ^]

It is clear from Table 1 above that these variables all affect the sulphuration of the residue. The influence on sulfur removal by molten potassium hydroxide reagent within the range of 25-200 weight percent, preferably 50-150 weight percent of the feed by the treatment is shown The water content of the molten potassium hydroxide should be within the range of 5-30 percent by weight, preferably 7-25 percent by weight. The optimum water content is about 15 percent by weight of water. As can be seen above, the temperature desulfurization obtained and the temperature substantially affected during the contact time should therefore in the range 204-427 ⁰ C, preferably 232-399 ° C and in particular 260 "371 ⁰ C. Furthermore, the longer the treatment time, the greater the desulfurization, but the relative effectiveness decreases when the treatment times increase for about 4-6 hours. Preferably, treatment times within the range of about 1/4 to 4 hours are recommended.

The above data were obtained from a one-step process * The conditions from a one-step process are generally applicable to the two ", three- or multi-step process" However, this is limited in that it has surprisingly been found that subsequent step operations under less severe conditions the temperature and time could be carried out and still a good one

0 09829/127 3 - 2? -

Desulphurization resulted, and also reduced the degradation of the product in terms of gas yield to a minimum. In general, however, the above amount of alkali metal reagent based on charge could be contacted with the treated oil within the broad range discussed above. However, it is preferable in view of better utilization of the reagent in general, the oil to be treated with, for example 20 ♦ · 50 percent by weight of reagent in each of the two or more stages, each with reduced treatment time in contact to \

bring so that the entire treatment time and the whole reagent used approximately approximately the same as to achieve the maximum desulphurizing effect when carried out in a single stage.

Example 2 t

This experiment was carried out to demonstrate the high levels of sulfur and metals removed by the Use of water containing molten potassium hydroxide of the present invention is achieved. The Experiments were carried out in two physically different environments; namely in an autoclave and in one stainless steel open container. Three different feeds were investigated · In two series of tests the autoclave was used to prevent losses of borne hydrocarbons cus to avoid the more volatile loads. Contacting and oil recoveries were in both cases, namely both in the autoclave and

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in the case of the open container ** try by the same general Procedure as described in Example 1 "carried out.

The results of the tests are shown in Table II with the Temperature and contact time of each set of experiments reproduced. In each experiment the molten KOH contained 15 weight percent water based on total reagent and the reagent was applied in equal amounts by weight as the treated batch. "During these experiments only traces of gas or coke were formed.

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TABLE II

distance from Metal and sulfur by molten KOH-H ₂ O reagent 371 40 5
88 based on the total reagent (D 343 ° C heavy
Sea mixture ro 8121/628600 4.0 0 4.2 2.9
31 316 One-step procedure Bschkg. Prod. Bschkg. Prod. - - 2 ---- 15 weight. $ Water 400 20
95 Bschkg. Prod. Contact vessel Autoclave with Nickel lining 2.5 2,
20th Open container 700 2 - * j
100 * feed 2O4 ° C heavy 371 ⁰ C Kuwait
Sea mixture - - 51O ⁰ C Kuwait - - Treatment tem
temperature in C 343- 316 100 0.5
100 Contact time in
hours 2.5 4.0 (1) These data illustrate the water retention characteristics of KOH under atmospheric pressure and
high temperatures, there. little or no water from the molten reagent during the _{OT treatment}
was not lost either from the autoclave or from the open container. 4 ^ Investigations Bschkg. Prod. % distant
Vanadium, ppm 90 5
95 % more distant
Sulfur, wt. # 5.2 2.8
46 % distant
Nickel in ppm - - ¹

ar

Example 3 t

tr

In order to show comparatively the advantage obtained by an intermediate stage treatment with molten alkali metal hydroxide as in the comparison between the two-stage and the three-stage process and to illuminate the influence of the varied temperature between 316 and 382 °, the following series of tests were carried out »A Kuwait Valuum- Residue with an API density of 6.2, an Oonradson coke test of 8.3 percent by weight, a sulfur content of 5.4 percent by weight, nitrogen 0.36 percent by weight, nickel 27 ppm, vanadium 70 ppm and an initial boiling point (normal pressure) of 453 ° C and a final boiling point (under normal pressure) of 564 ⁰ C after distillation of 10 $ was brought into contact with amounts of between 0 and 200 percent by weight of molten alkali metal hydroxide with 15 $ of water in the molten alkali metal hydroxide for a time of 4 hours in each stage . The reaction was carried out at 316 ^° C. both in the first and in the second stage. The desulfurization obtained by the reaction is plotted graphically in FIG. 2 of the drawings. It can be seen from this drawing that the maximum desulfurization that can be achieved in a single-stage treatment is only 46 percent by weight, even with 1Q0 # alkali hydroxide reagent. A second stage reduces the amount of sulfur still present by about $ 40 to $ 50 so that it is possible, for example, to remove substantially more sulfur than a one-stage treatment at 100 using two 50% by weight treatments with KOH Longer dosage would be possible.

0 0 9 8 2 9/1273. " ^2T "

Figure 3 of the drawings illustrates the single stage and. Two step process for the same residue and under the same conditions except that the temperature is 382 ° C. It can easily be seen that as the temperature increases from about 316 ^° C. to about 382 ^° C., the results in terms of the amount of sulfur removed at each treatment step increase substantially.

4 of the drawing illustrates a three-stage treatment carried out at 371 ° C .; otherwise under the same conditions as in Figure 2 and 3. From FIG · _o 4 it can be seen that when approximately 50 ^ strength dosage of the sulfur contained in the feed which is fed to a single reaction stage, by about 40 - 5O 6 of the sulfur contained is reduced in each stage and that even excessive amounts of alkali no longer significantly increase the amount of sulfur removed. The conditions and the results obtained from the reactions explained in FIGS. 3 and 4 are shown in Table III below:

Plate III
step

temperature

i » KOH in the loading
Treatment time in hours

oil product obtained

Weight percent S

j » Desulfurization

fresh load 55 48

at the level lift * 55 48

1 382 2 2 2 382 50- 382 100 50 4th

2.4 2.8

1.4

74 50

2 B. 'J. 2 D. 4th T 2.8 371 2.0 371 1.2 371 48 50 63 50 78 50 48 29 40

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Continuation of Table III ^A

Percentage by weight of gas formed 0.6 0.4 1.8

KQH consumption analysis Weight spro ζ ent

KOH - - -

K ₂ S as KOH K ₂ CO ₅ as KOH

0.4 0.4

54 79

18 7 12

28 14 14

It is noted that a greater degree of desulfurization is obtained with two stages than with one stage using the same amount of KOH at the same time. For example, with regard to column A, a 100% dosage for a period of 4 hours results in a 55% desulphurisation. When desulfurization was carried out in two stages with 50 # dosing for two hours in each stage, 74 # desulfurization was obtained. According to column B, the second and third stages give almost the same degree of desulfurization in each stage, based on the feed to the respective stage, as was obtained in the first stage. Of particular interest is the amount of gas formed in the following stages; In these subsequent stages, a larger amount of gas is formed, so that a reduction in the severity of the reaction conditions by lowering the temperature and / or the contact time is desirable. Despite this reduction of the sharpness of the operating conditions (di 1 hour for 2 hours), the step 3 was found of 371 ⁰ C experiment, was that the degree of desulfurization nioht substantially decreased.

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When treated with KOH in stages, there was a remarkable increase in the amount of gas generated in the last Stage found after the sulfur had been reduced from 5.4 to below 1.5 percent by weight. It is probably that the cause of this increase in gas formation at this reduced sulfur level in the reaction we must look for certain types of sulfur compounds which, according to their constitution, are gas-forming, as already mentioned in the analysis of the recovered from the various stages Alkalis noticed that there is a considerable amount of KOH from the later stages that is used for desulfurization could be used in the initial stages «This stage process, both liquor and batch, would allow greater utilization of the lye. The use of this process allows a good desulfurization of the Distillates and the use of low sulfur feeds which have heretofore not been considered appropriate for treatment with molten KOH.

It can be expected that when using the countercurrent « management of oil and alkali in a multi-stage process for both components, both an improved utilization of the alkali and a high level of sulfur removal achieved would. Contains the alkaline phase which is recovered from the second and third treatment stages More than $ 75 free alkali · This alkali should be used for one Desulphurization to be effective in the initial stage »

-JO-009829/1273

Example 4t

It has been found by the applicant that the temperature at which the reaction mixture settles, namely either from the first, the "wide" or the third desulfurization · reaction zone, particularly crucial for effective Phase separation is. It has been found, surprisingly, that the reaction mixture very rapidly at temperatures of settles above 177 ° C. To explain this, a Kuwait vacuum residue was as described in Example 3, at 371 ° for 2 hours with about 50 percent by volume of molten KOH reagent, which has a water content of 15 weight percent had brought into contact. Several samples of this mixture were separated, with about the the same amount of water is added and the temperature is reduced. cools, as shown in the drawing in FIG. It has been found that at temperatures below about 177 C the Emulsion was stable or an excessively long period of time for effective separation of the oil from the inorganic aqueous solution. However, at about 177 C and above, a sharp separation was observed in of the reaction mixture observed, so that an effective separation of an anhydrous desulphurized oil layer and an aqueous inorganic layer came about. The results obtained are shown in Table IV.

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T a b. e 1 1 e IV

Treatment at 371 ^° C. with KOH with 15 $> Water content for a period of 2 hours

Washing temperature separation after 1 hour

399 good

316 good

260. Well

204 good

177 satisfactory

149 only

93 low

38 none

The separation of the inorganic products from the oil product in the KOH desulphurization of petroleum residues and heavy Λ crude oils has been difficult to carry out in the past. Such separation is necessary, however, in order to take advantage of the potential for sulfur removal by the molten alkali metal hydroxide reagent. In a commercial process it is necessary to recover all proportions, even traces of potassium compounds for the regeneration to potassium hydroxide for its reuse and also to remove trace amounts of potassium from the oil before it is used as a fuel »

The applicant found that the inorganic or the oil phase from the KQH «desulphurization can be separated with ease can if the desulfurization stage in terms of time and the temperature was carried out under such conditions as to cause lowering of the viscosity of the oil phase. It is essential that this decrease in viscosity be sufficient to reduce the viscosity of the oil product

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less than 100 SSU at 177 ° C and preferably reduced to less than 50 SSU at 177 ° G. Such desulphurization conditions depend somewhat on the feed used and can be achieved at temperatures of about 343 to 399 ^° C. with a contact time of about one hour. There is an inverse relationship between time and temperature in that less contact time is required at higher temperatures ο

The water washing is carried out effectively by bringing the product mixture into intimate contact with an equal amount by weight of water to the KOH, at a temperature such that after cooling the temperature of the mixture is slightly above 177 ^° C. and the phases separate at this temperature can. The oil product can then be removed by filtration, centrifugation or bleaching earth treatment of traces of remaining water b * w. Lye to be freed.

The decisive fact of this sequence of lower viscosity and high-temperature phase separation is illustrated by the results obtained with Kuwait vacuum residues. The desulfurization of these residues with 20? £ KOH to oil-Inberührungbrlngen for the duration at 382 ⁰ C an hour not a good separation resulted in the wash water at 177 ⁰ C, contrast, showed a InberührungDringen for a period of swel hours at 382 ⁰ C good results in the phase separation. The decrease in viscosity achieved is of course advantageous for a subsequent one

- 33 ' 009829/1273

Use of the oil product, especially since a reduction in viscosity is usually required, to a common Product to receive.

The exact settling time and treatment temperature as well the ratio of water to KOH in the emulsion becomes somewhat with the viscosity of the particular feed being treated vary"

Claims

009829/1273

Claims (12)

Claims 1.1 Procedure for removing sulfur and others Contaminants from hydrocarbons due to treatment with molten alkali metal hydroxide, characterized in that the treatment of the hydrocarbons with molten alkali metal hydroxyl, which is based on 5 Mb 30 wt. # of water on the total reagent *, contains, in at least two Stages is carried out. 2. Process according to claim 1, characterized in that the hydrocarbons are treated in the first stage with the alkali metal hydroxide until the sulfur content is reduced by 20 to 60 wt ° P («177 ⁰ C) formed, the partially desulfurized hydrocarbons containing oil layer separates from the aqueous layer containing the partially used alkali metal hydroxide and part of the sulfur, this oil layer in the second stage with additional, molten 5 to 30 wt. ^ Water containing alkali metal hydroxide up to the reduction of the sulfur still present by 20 to 60 Gew.ji treated and again by adding a 009829/1273 - 35 - suitable solvent for the treatment product
at temperatures above about 35O ⁰ P (= 177 ° C) two
Forms phases and withdraws the hydrocarbon phase. 3. The method according to claim 1 and 2, characterized in that the alkali metal hydroxide is potassium hydroxide, 4. The method according to claim 1 to 3, characterized in that the treatment at! Temperatures of about 400 to 800 ⁰ P (= 204 ° to 427 ⁰ C) with in each stage an amount of alkali hydroxide of about 10 to 100 wt. #, based on the loading. 5. The method according to claim 1 to 4, characterized in that the treatment time in each stage 0.1 to
16 hours. 6. The method according to claim 1 to 5, characterized in that in the stages following the first stage the treatment time is shorter and the amount of alkali hydroxide used is lower than in the first stage. 7. The method according to claim 1 to 6, characterized in that the treatment temperatures in the on
first level lower than in the following levels
first stage are. 009829/1273 "" ³⁶ " 164S724 8. The method according to claim 1 to 7, characterized in that the treatment of the hydrocarbons with the alkali metal hydroxide as a continuous Downstream procedure is carried out. 9. The method according to claim 1 to 8, characterized in that water is used as the solvent for the material to be treated. 10. The method according to claim 1 to 9, characterized in that the hydrocarbon in at least treated in one stage with a partially spent, molten alkali metal hydroxide reagent will. 11. Vtrfahren according to claim 1 to 10, characterized in that a hydrocarbon is used which contains a sohwere petroleum fraction with components that ^{boil over about 95O 0} P (* 510 ⁰ C). 12. The method according to claim. 1, characterized in that one a) the hydrocarbon in at least three stages in countercurrent with the alkali metal hydroxide in each level from 0.25 to about 4 hours below - 37 -009829/1273 645724 Reduction of the sulfur content present in each case by about 30 to 60 wt. #. treated, whereby b) in the first stage the hydrocarbon is treated with partially used alkali metal hydroxide reagent and from the material to be treated after transferring to a settling tank and formation of a hydrocarbon phase and a Aqueous phase by adding water, the aqueous phase is separated and the alkali metal - reagent is regenerated while distilling off the excess water, and the regenerated Alkali metal hydroxide reagent in the third stage reintroduces, and that one c) the partially deeulfurized hydrocarbon oil the first stage in a second stage again with partially consumed alkali metal hydroxide Treated reagent from this item to be treated after adding water and forming a desulfurized oil phase and an aqueous phase, the aqueous Phase withdraws, after excess water has been distilled off, the concentrated molten product obtained Adds alkali metal hydroxide reagent to the first stage and then - 38 - 009829/1273 HO d) the desulfurized oil in a third stage with essentially fresh alkali metal hydroxide reagent treated by this treatment product after washing with water and forming a aqueous and a hydrocarbons off layer the aqueous layer peeled off and distilled off of the water from this fed to the second stage concentrated, partially used alkali metal hydroxide reagent feeds and you finally e) the desulfurized, subtracting the Schwefelgehaltea substantially reduced with respect to oil and freed in a Waechzone by treatment with a suitable washing liquid notice any entrained Alkalinetallhydroxyd reagent and separated. 009829/1273