TW522168B - Process for the desulfurization of petroleum feeds - Google Patents

Abstract

A process for the hydrodesulfurization of a cracked naphtha stream is disclosed where very little of the valuable olefins are saturated. The process is a two staged process wherein the H2S is removed between the stages to prevent recombinant mercaptans formation. Because the H2S is removed between the stages milder conditions can be used in the second stage polishing reactor to achieve the same desulfurization levels with less olefin loss.

Description

522168 Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 --------- B7 V. Description of the invention (1) Background of the invention The present invention relates to a desulfurization method for fluid catalytic cracking of light oil in the final boiling range. It is carried out in the presence of a hydrodesulfurization catalyst by the reaction of hydrogen with an organic sparse compound present in the feed. In particular, the present invention makes it possible to use a catalytic distillation step that reduces the porosity to a relatively low level, making the use of hydrogen more efficient and the hydrogenation of the hydrocarbons of the light oil fluid in the final boiling range less. Petroleum distillate fluids contain various organic chemical components. The fluid is generally defined by the boiling point range that determines the composition. The processing of the fluid also determines the composition. For example, the product of a catalytic cracking or thermal cracking method contains high concentrations of thallium hydrocarbons and saturated (alkanes). ) Substances and polyunsaturated (diolefinic) substances, in addition these components can be various isomers of any of these compounds. When untreated light oil comes from a crude oil distillation pot or straight run light oil, its composition is still mainly affected by the source of the crude oil. Light oil derived from paraffin crude oil has more saturated linear or cyclic compounds. As a general rule, most "sweetened" (low sulfur) crude oils and light oils are paraffin. Naphthenic crude oils contain more unsaturated, cyclic and polycyclic compounds, and higher sulfur content crude oils. Tends to naphthenes. The treatment of different straight run light oils varies slightly depending on the composition of the source of the crude oil. Reconstituted light oils or reconstituted products may generally be distilled or solvent extracted to remove valuable tritium aromatic products. Further processing is required. The recombined light oils are basically free of sulfur pollutants. This is because of their pretreatment before the process and the rigorous method itself. Because the cracked light oil comes from the catalyst cracking tower, because it contains olefins and aromatic compounds Therefore, it has a relatively high octane content. In some cases, this fraction can contribute up to half of the gasoline and a significant portion of octane in the refining industry. ) --- 0 ^ -------- tr · -------- (Please read the notes on the back before filling this page) 522168 A7 B7 V. Description of the invention (2) Medium cracked light oil gasoline boiling range substances currently form a significant portion of gasoline products 1 / 3) And it provides the largest part of sulfur. Sulfur impurities need to be removed, generally hydrogenated to meet product specifications or to ensure compliance with environmental regulations. Some users want sulfur in the final product to be less than 50 parts per million by weight --- 〇 The most common method for removing sulfur compounds is hydrodesulfurization (HDS), in which petroleum distillates are passed through a solid particle catalyst comprising a hydrogenated metal supported on an alumina substrate, and the feed includes an additional abundant amount of hydrogen. The following formula illustrates Reactions in a typical HDS unit: (1) rsh + h2… ► rh + h2s (2) RC1 + H2… ► RH + HC1 (3) 2RN + 4H2 RH + NH3 (4) ROOH + 2H2 RH + H20 HDS reaction typical Operating conditions are: temperature, F pressure, pound per square inch gauge H2 cycle rate, standard cubic feet per barrel of fresh H2 supplement, standard cubic feet per barrel 600-780 600-3000 1500-3000 700-1000 (please read first Note on the back, please fill out this page again.) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. After the hydrogenation process is completed, the product can be fractionated or separated only by rapid separation to release hydrogen sulfide and collect the desulfurized light oil at the time. Olefin loss due to light The reduction of octane hydrazone in oil and other applications is harmful. In addition to the supply of high-octane mixed ingredients, cracking light oil is commonly used in other methods such as the source of fluorene in esterification reactions, hydrogenation of light oil components. The conditions for removing sulfur are also -5 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 522168 A7

V. Explanation of the invention (3) It will saturate the olefin compounds in some distillates, and reduce the octane and phantom the loss of the source and natural hydrocarbon. (Please read the notes on the back before filling out this page) Various Jianye have been proposed to remove sulfur, but still preserve the more desirable olefins. Because olefins in cracked light oils are mainly low boiling distillation of these light oils Sulfur containing impure substances tends to concentrate on high boiling fractions. The most common solution is to pre-fractionate before hydrogen treatment. Prefractionation produces light boiling range light oils that are distilled out in the range of C5 to about 250 and heavy heavy range light oils that are distilled out in the range from about 250 to 475. Wang Yao's light or lower boiling sulfur compounds are thiols, while heavier or higher boiling compounds are pyrimidines and other heterocyclic compounds. Solvents alone cannot be removed by the separation of the branch, however, in the past mercaptans were removed by oxidation methods involving inspection. The oxidative removal of the thiol is followed by the fractionation of the heavier fractions and the addition of air and is not disclosed in U.S. Patent 5,320,72. In the oxidative removal of the thiol, the thiol is converted to the corresponding disulfide. Printing of US Patent No. 5,597,476 by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economics discloses a two-step process in which light oil is fed to a first distillation column reactor, which is used as a pentane distillation column or a hexane distillation column. Part of the lighter substances of the olefin and the thiol are distilled out to the first distillation reaction zone, where the thiol reacts with the diene hydrocarbon to form a sulfide, which is removed at the bottom along with any more boiling compounds and the bottom fluid is sent. The second distillate column reactor is subjected to a hydrodesulfurization reaction, where the sulfur compounds are converted into H2S and removed. The use of two or more continuous hydrodesulfurization processes has actually been used to treat petroleum feedstocks to remove organic sulfur compounds, however in these prior processes, there is a significant amount of "recombined sulfur" in the product. Combined with sulfur, it represents a new organic sulfur compound, mainly a thiol, which is the reverse reaction of the previous hydrodesulfurization of H2S _ 6-This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) A7

522168 V. Description of the invention (4) or subsequent hydrodesulfurization is formed by hydrodesulfurization of olefinic feedstock. J_J2S can be recombined to form a thiol to increase the amount of sulfur in the product. The presence of H2S will also cause more olefins to be saturated, reducing octane and consuming hydrogen. The products from the subsequent multi-layer bed hydrodesulfurization are of course less sulfur-containing than the less-processed feed, but the recombination of sulfur makes each subsequent treatment less efficient than expected. In this method, the efficiency of subsequent processing is improved by stripping H2s from the processed feed before passing the feed through subsequent hydrodesulfurization. The advantages of the present invention are that through continuous hydrodesulfurization that is removed after each hydrodesulfurization, the final boiling range light oil fluid is hydrodesulfurized and the olefin content is maintained at a high ratio of the original feed. In the prior art, Xian did not think that H2S could be removed in the hydrodesulfurization process of continuous hydrodesulfurization. In previous applications, H2S was removed after the final hydrodesulfurization. SUMMARY OF THE INVENTION The present invention relates to a method for hydrodesulfurization of petroleum feedstocks containing organic sulfur compounds and preferably olefins. This method is to continuously feed at least two feedstocks in contact with hydrogen in the presence of a desulfurization catalyst. In order to convert a part of organic sulfur compounds into Ηβ, it is modified to remove H2S from the feed after each treatment. In a specific embodiment of the present invention, a final boiling Fanyuan light oil is placed A two-stage process was introduced to remove organic sulfides by hydrodesulfurization. In stage f, the final boiling range of light oil is desulfurized in the distillation column reactor. This reaction uses I a to raise ¥, which dehydrolyzes the light lining; it is used as the top distillate and is accompanied by slaves. H2S produced in the reactor, a significant part of H2S from the top of the tower -11 — 丨 installed · " * i 丨 —! H order · Bu-丨 丨 丨 丨-* ^ 11 ^ (Please read the phonetic on the back? Matters before filling out this page) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs -7- 522168

5. Description of the invention (6) Light oil has relatively little sulfur. (Please read the precautions on the back before filling out this page) The sulfur content of catalytic cracking thorium depends on the sulfur content of the feed to the cracking tower and the range of feeds selected for the method used to feed. It has less sulfur content than the distillate. The light ends of light oil contain most of the high-octane sulfonium but relatively little sulfur. The sulfur components in the light ends are mainly thiols, and these compounds are typically: methyl mercaptan (boiling point 43T), ethyl sulfur Alcohol (boiling point: 99T) n-propyl & alcohol (boiling point: 154 F), isopropyl mercaptan (boiling point: 135 · 14〇τ), butanethiol (stagnation point: 19〇τ), third butyl mercaptan (stagnation point: 147T) ), N-butyl mercaptan (stagnation point 208T), second butyl mercaptan (boiling point 203T), isoamyl mercaptan (boiling point 25〇τ), n-pentyl mercaptan (boiling point 259T), α · methylbutanesulfide Alcohol (boiling point 234T), ethyl ethyl thiol (boiling point 293T), n-hexyl mercaptan (boiling point 304T), 2-hydrothiothione (boiling point 284T), and 3-hydrothiothione (boiling point 135) under). Typical sulfur compounds found in heavier boiling fractions include heavier mercaptans, refin, sulfides and disulfides. The reaction of organic sulfur compounds with hydrogen on the catalyst in the refining fluid to form HsS is generally called hydrodesulfurization. Hydrogenation is a broader term that includes #hydrocarbon and aromatic saturation and the reaction of organic nitrogen compounds to form ammonia. Hydrodesulfurization is, however, included and sometimes only referred to as hydrotreating. Printed by the Consumers' Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. Useful catalysts for the reaction of sulfur, sulfur and hydrogen include metals of the Group Vhi on suitable carriers such as cobalt, nickel, and palladium, which can be used alone or in combination with other metals such as molybdenum or tungsten 'The carrier can be an oxide, an oxide, an oxide, an oxide', or an analog thereof. These metals are generally provided as metal oxides carried on extrudates or balls, and such use as a distillation structure is generally not useful. The catalyst can additionally include the components of Group V and VIB metals in the periodic table or its -9- This paper size applies to China National Standard (CNS) A4 specifications (21 × X 297 mm) 522168 A7 B7 Intellectual Property Bureau employees of the Ministry of Economic Affairs Printed by Consumer Cooperatives

5. Description of the invention (7) Mixture. Group VIII metals provide increased overall average activity, and catalysts containing Group VIB metals such as molybdenum and Group VIII metals such as palladium or nickel are preferred. Catalysts suitable for use in hydrodesulfurization reactions include Mem-1 mesh, nickel- 钿, and nickel-_. These metals are generally oxidized on a neutral substrate such as oxide, hard dioxide, or similar. The metal is present, and the metal is reduced to a sulfide during or before use by being exposed to a sulfur-containing compound fluid. The properties of a typical hydrodesulfurization catalyst are shown in Table I below. Table I Manufacturer Criterion Catalyst Co. Name DC-130 Type Three Impellers General Size 1.3mm Diameter Metal, Weight% Ming 3.4 Molybdenum 13.6 Carrier Alumina Catalysts generally have a diameter of 1/8, 1 / 16 or 1/32 inch extruded type with L / D of 1.5 to 10, the catalyst can also be a sphere type with the same diameter. In their normal form, they form very compact masses and are better prepared in the form of catalytic distillation structures. The catalytic distillation structure must be able to function as a catalyst and as a mass transfer medium. The catalytic distillation structure that can be used for this purpose is disclosed at -10- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) (Please read the precautions on the back before filling this page) -Order -------- 522168 A7

V. Description of the invention (8) US patents 4,731,229, 5,073,236, 5,431,890, and 5,266,546, which are incorporated herein by reference. The use of a reactive steamer system (catalytic distillation) reduces deactivation and provides a longer operating period than a fixed bed hydrogenation unit and is better used as a first reactor. The distillate column reactor is advantageously used for the reaction of heavier or higher boiling sulfur compounds. The pressure at the top of the column is maintained at about 0 to 250 psig. The corresponding temperature in the distillation reaction zone is between 400 and 700 T, which can be used. The partial pressure of hydrogen is from 0.01 to 70 hours per square inch absolute. In a preferred embodiment, a hydrogen partial pressure of 0.1 to 10 can be used. Generally, the hydrogen partial pressure is 0.5 to 50 psi absolute pressure to obtain the most suitable result. The second reactor may be a gas-phase, single-pass, down-flow reactor because the major part of the sulfur compounds has been removed. Because of the more difficult sulfur compounds have been removed, the reactants can work in milder conditions, such as at a pressure of about 2000 pounds per square meter gauge, a reaction temperature of 500T, and a three-hour hourly space velocity. If a second distillation column is used, a lower total pressure of 25 less than 300 pounds per square inch gauge is necessary for hydrodesulfurization, and a hydrogen partial pressure of less than i50 pounds per square centimeter can be used, as low as 0.1 pounds per square inch. Square torr is preferred, preferably from about 15 to 50 torr / square torr, and the temperature of the distillation reaction zone is in the range from 400 to 750 ° F. The hydrogen in the second distillate column reactor is injected into the range of one to ten standard cubic feet (SCF) per pound of feed. 'The second hourly space velocity of liquid in the second distillate tower (feed liquid volume per unit of contact volume) is 2 -5 range. Typical conditions in the reactive distillation zone (second and subsequent columns) of a light oil hydrodesulfurization distillation tower reactor are: -11-This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) ( Please read the phonetic on the back? Matters before filling out this page) Packing-Order --------- Printed by the Intellectual Property Bureau of the Ministry of Economic Affairs and Consumer Cooperatives 522168 A7 B7 V. Description of the invention (9 Total temperature pressure h2 partial pressure Light oil LHSV H2 rate

450-700〇F (Please read the notes on the back before filling this page) 75-300 psig absolute pressure 6-75 psig absolute pressure about 1-5

The operation of the 10-1000 SCFB steam reactor i reactor allows liquid and gas phases in the distillation reaction zone. A considerable part of the vapor is hydrogen and a part is vaporous hydrocarbons from petroleum. Actual separation may be only a secondary consideration. It is proposed in a way that does not limit the scope of the present invention that the mechanism for generating a hydrogenation effect in the distillation column reactor is the condensation of a part of the vapor in the reaction system, which absorbs enough hydrogen in the condensed liquid to obtain hydrogen and sulfur compounds in the presence of the catalyst. The necessary close contact to complete their hydrogenation. In particular, the sulfur materials are concentrated in the liquid phase and the olefins and Hj are concentrated in the gas phase, resulting in a high conversion rate of sulfur compounds and a low conversion rate of fluorene. Printed in the Sikan tower reactor by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. The operation result of this method is that a lower hydrogen partial pressure (and thus lower total pressure) can be used, as in any distillation. Temperature gradient. The temperature at the lower end of the column contains higher boiling point materials, which makes it higher than the top of the column. Lower boiling point fractions containing sulfur compounds that are easier to remove are placed at a lower temperature at the top of the column, which provides greater selectivity, i.e. less hydrocracking or saturation of the famous olefin compounds, and higher boiling fractions are placed. The higher temperature of the bottom of the distillation column reactor is used to crack open the sulfur and hydrogen sulfide containing cyclic compounds. Between the two reactors is a Hj stripping tower, which effectively removes from the first tower-12- 522168 printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 B7 V. Invention Description (1) H2S is separated and passed through the flow tube 14 is returned to the second stripper for reflux, and excess hydrogen and S are removed through the flow tube 14. The final product is removed via the flow tube 9 as a bottom product. Since H2S is removed in the reactor, milder conditions can be used in the second reactor so that the olefins are not subjected to hydrogenation conditions. Referring now to Figure 2, there is shown a second specific embodiment of the present invention, in which the first reactor is a distillate tower reaction of two beds 11a and 11b containing a hydrodesulfurization catalyst in the form of a catalytic distillation structure.器 10。 10. Light oil is fed between the two beds via flow tube 1 and hydrogen is fed from under the bed via flow tube 2.Since the catalytic distillation column is operated at a lower pressure, less olefins are saturated, and the catalytic distillation column is hydrogenated such as methane. And benzopyrimidine heavy sulfur compounds are also more efficient. Light and light oil passes through the flow tube 4 with excess hydrogen and most of the H2S produced in the bed as the overhead distillate. The reactor 50 is condensed and collected in the separator 60. Here, the vapor including H2S and excess hydrogen is removed through the flow tube 12, and a part of the condensed liquid is sent back to the distillation column reactor 10 as the reflux through the flow tube 13, and the remaining liquid is overhead. The distillate is fed to the upper section of the stripping column 20. The bottom product from the distillation column reactor 10 is also fed to the stripping column 20, but enters the lower section via the flow tube 3. The stripping column strips H2S from the overhead distillate through the flow tube 15. The condensable matter in the overhead distillate is condensed in the condenser 21 and collected in the separator 22, where it is combined with excess hydrogen and H2S is separated, excess hydrogen and H2S are removed from the separator through the flow tube 16 and the liquid is sent back to the stripper via the flow tube 23 as reflux, and the final product is removed through the flow tube 9 as the bottom product. The side stream is removed from the stripping column 20 via the flow tube 5 and fed to a fixed-bed single-pass reactor 30 containing an appropriate hydrodesulfurization catalyst bed 31, where it is compared (please read the precautions on the back before filling in this Page) Binding -------% _ -14- This paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm) 522168 V. Description of the invention (13) ASTM D-2887 Steamed surplus 5% 16〇 ° F 10% 174 20% 205 3 0% 23 1 40% 258 5 0% 283 60% 320 70% 338 80% 382 90% 419 95% 442 (Please read the note on the back? Matters before filling in this (Page) ---- ^ Order ί Printed by the Consumers' Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs, the catalytic distillation tower is operated at a top pressure of 230 psig to obtain a catalyst urine temperature of 570 ° F. Only the catalytic distillation tower is operated. Produced 96 7% sulfur removal and 46.47% bromide loss (olefin loss). Data from a commercial fixed-bed single-pass hydrogenation column show that at the same level of sulfur removal, approximately 85% of the associated hydrocarbons (bromine #) are obtained. Only H2S and excess hydrogen are stripped from the top distillate of the autocatalytic distillation column and processed in the second-stage traditional single-pass fixed-bed refining reactor containing the same catalyst under the following conditions: 16- This paper size is applicable to China Standard (CNS) A4 specification (210 X 297 mm) See 522168 A7 V. Description of the invention (14 WHSV hydrogen rate average temperature pressure 113.4 standard cubic feet / barrel 470 ° F 200 list / square inch gauge pressure The combined desulfurization rate is 97.2% and only 43 4% associated, the second-stage refining reactor operates on very mild strips and clearly shows that compared to the single-stage method, the operation according to the present invention is the second: the selectivity of the two methods. From examples only 2 The feed to the distillation column reactor described in Example 1 was processed as described in Example 1, only the overhead of the column was steamed to excess hydrogen and processed in the purification reactor under the following conditions to reach 27 parts per million by weight No. 1 light oil: WHSV hydrogen rate average temperature pressure combined olefin saturation 104 standard cubic feet / barrel 510 ° F 275 psig gauge 51.5% (please read the precautions on the back before filling this page) • Installation --- Order —------% Printed by the Consumer Property Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs, the overall conversion rate is 98.96%, and the olefin saturation is 51.5%. Data from commercial single-pass fixed-bed units show that the same degree of desulfurization can be expected. 92% olefin loss. Example 3 A cracked light oil with the following characteristics is contained in the commercial standard DC-130 / Mo-17- 'Paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 522168 A7 B7

V. Description of the invention (15) Catalyst 1 The catalytic distillation column of Example 1 was treated as described.

Feed description Total sulfur 1554 mg / l Total nitrogen 132 mg / l Bromium 30.5 Density 0.8288 g / ml @ 15.66 ° C c Please read the note on the back first? Matters refill this page: > ASTM D-2887 Distillation

5% 195T 10% 229 20% 265 3 0% 288 40% 322 50% 336 60% 362 70% 384 80% 39990% 412 95% The column top pressure of psig gives a catalyst bed temperature of 590 ° F. Operating only the catalytic distillation column produces 98.98% sulfur removal and 66.15% olefin loss. However, the total sulfur content is about 24 parts per million by weight. The combined top distillate and bottom distillate were stripped of H2S and excess hydrogen in the refining reactor under the following conditions to reach -18 with a content of only 7 parts per million by weight.- This paper applies Chinese national standards (CNS) A4 specification (210 X 297 mm) 522168 A7 B7 V. Description of invention (16) Light oil: WHSV hydrogen rate average temperature pressure combined with olefin saturation 12 8 8 standard cubic sigh / barrel 510 ° F 230 pounds per square inch Gauge 67.4% to 99.7% sulfur conversion. Data from commercial fixed-bed single-pass hydrogenation towers show that approximately 95% olefins are lost at the same degree of desulfurization. (Please read the notes on the back before filling out this page) I I I I I I l · Order — l · I I — I I--

P Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs -19 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

Claims (1)

522168 Patent Application No. 90100930 Amended Chinese Patent Application Range (March 91) A8 B8 C8 D8 Scope of Patent Application 1. A method for hydrodesulfurization of cracked light oil fluids, comprising the steps of: (a) feeding hydrogen and a light oil fluid containing organic sulfur compounds and olefins to a hydrodesulfurization catalyst (B) in the distillation column reactor, while (1) contacting the cracked light oil and the hydrogen with the hydrodesulfurization catalyst under hydrodesulfurization conditions, Portions of the organic sulfur compound with the conditions to keep the olefin unsaturated and the hydrogen to form 1128, the conditions to keep the olefin unsaturated; and (2) the light oil is distilled off at less than about 250 T Light fractions and heavy fractions distilled above about 250 ° F; (c) removing the light fractions from the distillation column reactor as overheads and reacting with H2S and unreacted Hydrogen is removed together; (d) the heavy fraction is removed from the distillation column reactor as a bottoms distillate; (e) the heavy fraction and the light fraction are combined to form a first combined distillate And remove H2S from it; (f) after Η2 S is removed, feed a portion of the first combined library to a A fixed-bed single-pass reaction zone of a sulfur catalyst in which a portion of the remaining organic sulfur compounds reacts with hydrogen to produce H2s and a second combined distillate; (g) shifted from the second combined distillate of step (f) Removal of H2s; and (h) recovery of organic sulfur compounds contained is substantially less product fluid than the cracked light oil fluid. 2. Method according to item 1 of the scope of patent application, in which the second combined paper size of the step is applicable ® ® Standardization (CNS) A4 specification (210 X 297 mm) 522168 A8 B8 C8 The first combined fractions combine and remove H2s. 3. The method according to item 1 of the patent application scope, wherein the organic sulfur content of the second H2s reducing fluid is less than 50 parts per million by weight (Wppm). 4. The method according to item 1 of the patent application scope, wherein the hydrodesulfurization catalyst comprises a Group VIII metal. 5. The method according to item 4 of the scope of patent application, wherein the hydrodesulfurization catalyst comprises a Group V metal. 6. The method according to item 5 of the scope of patent application, wherein the hydrodesulfurization catalyst comprises a Group VIB metal. 7. The method according to claim 4, 5, or 6, wherein the hydrodesulfurization catalyst comprises an oxide. 8. The method according to claim 4, 5, or 6, wherein the hydrodesulfurization catalyst comprises a sulfide. 9. A method for hydrodesulfurization of cracked light oil fluids, comprising the steps of: (a) feeding hydrogen and light oil fluids containing organic sulfur compounds and associated hydrocarbons to a distillation column containing a hydrodesulfurization catalyst Reactor; (b) in the distillation column reactor, (1) contacting the cracked light oil and the hydrogen with the hydrodesulfurization catalyst under hydrodesulfurization conditions, thereby part of the organic Sulfur compounds are required to keep the hydrocarbons unsaturated and the hydrogen to react to form H2S; and (2) divide the light oil into lighter fractions that evaporate at less than about 250 ° F and ° F heavy fractions distilled; (c) remove the light fractions from the distillation column reactor as overhead distillate -2-This paper size applies to China National Standard (CNS) A4 specifications (210 x 297 mm) Install ij m 522168 8 8 8 8 AB c D 6. Apply for patent scope and remove it together with h2s and unreacted hydrogen; (d) Remove the heavy fraction from the distillation column reactor as bottom distillation (E) combine the heavy fraction and the light fraction to form a first combined fraction and remove H2S therefrom; (f) after the H2S is removed, part of the first combined fraction Feed to a fixed-bed single-pass reaction zone containing a hydrodesulfurization catalyst, a portion of the remaining organic sulfur compounds react with hydrogen to produce H2S and a second combined fraction; (g) from step (f) The second combined distillate removes H2S; and tritium recovery contains substantially less product fluid than the cracked light oil fluid. 10. The method according to item 9 of the scope of patent application, wherein the organic sulfur content of the second reducing fluid is less than 50 parts per million by weight (wPPm). 11. The method according to item 9 of the scope of patent application, wherein the hydrodesulfurization catalyst comprises a Group VIII metal. 12. A method according to item 11 of the scope of patent application, wherein the hydrodesulfurization catalyst comprises a Group V metal. 13. A method according to item 12 of the scope of patent application, wherein the hydrodesulfurization catalyst comprises a Group VIB metal. 14. The method according to the scope of application for patent No. 丨, 12, 2 or 13 ', wherein the hydrodesulfurization catalyst comprises an oxide. 15. A method according to claim 11, 12, 12 or 13 'wherein the hydrodesulfurization vehicle comprises a sulfide. -3- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)