DE60208420T2 - SULFUR REMOVAL PROCESS - Google Patents

Abstract

A product of reduced sulfur content is produced from an olefin-containing hydrocarbon feedstock which includes sulfur-containing impurities. The feedstock is contacted with an olefin-modification catalyst in a reaction zone under conditions which are effective to produce an intermediate product which has a reduced amount of olefinic unsaturation relative to that of the feedstock as measured by bromine number. The intermediate product is then separated into at least three fractions of different volatility, and the lowest boiling first fraction is contacted with a hydrodesulfurization catalyst in the presence of hydrogen under conditions which are effective to convert at least a portion of its sulfur-containing impurities to hydrogen sulfide. The intermediate boiling fraction is contacted with a selective hydrotreating catalyst in the presence of hydrogen under conditions which are effective to convert at least a portion of its sulfur-containing impurities to hydrogen sulfide.

Description

Territory of invention

These The invention relates to a process for the removal of sulfur-containing Impurities from olefin-containing hydrocarbon mixtures. In particular, the process involves converting the feedstock to an intermediate with reduced bromine number, separating the Intermediate in fractions with different boiling point and subjecting the high boiling fraction to hydrodesulfurization and the middle-boiling fraction of a selective hydrotreating.

background the invention

The fluidized catalytic cracking process is one of the main refining processes, currently in the conversion of petroleum to desirable fuels such as gasoline and diesel fuel is used. In this procedure becomes a high molecular weight hydrocarbon feed through a contact with hot, finely divided Feststoffkatalysatorteilchen in a fluidized or dispersed state to lower molecular weight products transformed. Suitable hydrocarbon feeds boil typically within the range of about 205 ° C to about 650 ° C, and are commonly used contacted with the catalyst at temperatures ranging from about 450 ° C to about 650 ° C. Suitable feedstocks include various mineral oil fractions like light gas oils, heavy Gas oils, wide blended gas oils, Vacuum gas oils, Kerosene, decanted oils, Residue fractions, reduced crude oils and return oils, the be obtained from any of these fractions or from fractions obtained from shale oils, a tar sands processing and a coal liquefaction come. Products from a fluidized catalytic cracking process are typically based on a boiling point and include light weight Naphtha (boiling between about 10 ° C and approximately 221 ° C), heavy naphtha (boiling between about 10 ° C and about 249 ° C), kerosene (boiling between approximately 180 ° C and approximately 300 ° C), light return oil (boiling between about 221 ° C and approximately 345 ° C) and heavy return oil (boiling at temperatures greater than about 345 ° C).

naphtha from a catalytic cracking process comprises a complex mixture from hydrocarbons containing paraffins (also known as alkanes), Cycloparaffins (also known as cycloalkanes or naphthenes), olefins (As used herein, the term olefin includes all acyclic ones and cyclic hydrocarbons containing at least one double bond contained and not aromatic) and aromatic compounds lock in. Contains such a material typically has a relatively high olefin content and includes significant Amounts of sulfur-containing aromatic compounds such as thiophene compounds and benzothiophene compounds as impurities. For example can be a light naphtha from the fluidized catalytic cracking one from petroleum recovered gas oil up to about Contain 60% by weight of olefins and up to about 0.7% by weight of sulfur, the majority sulfur in the form of thiophene compounds and benzothiophene compounds is present. A typical naphtha from the catalytic cracking process is however for usually of about 5% by weight to about 40 wt% of olefins and from about 0.07 wt% to about 0.5 wt% contain sulfur.

The Fluidized catalytic cracking process does not just provide one significant share of United States gasoline pool available it also represents a big one Share of sulfur emerging in this pool. The sulfur in the liquid Products from this process is in the form of organic Sulfur compounds and is an undesirable impurity, the when using the products as fuel to sulfur oxides is converted. The sulfur oxides are undesirable air pollutants. additionally can they disable many of the catalysts used for the catalytic converter which are used in motor vehicles to catalyze the conversion from harmful Engine exhaust emissions to less harmful gases. Accordingly, it is desirable, the sulfur content of catalytic cracking products to the lowest possible level to reduce.

Low sulfur products are usually obtained from the catalytic cracking process by hydrotreating either the feed of the process or the products of the process. The hydrotreating process involves treating the feed with hydrogen in the presence of a catalyst and converting the sulfur in the sulfur-containing impurities to hydrogen sulphide, which can be separated and converted to elemental sulfur. The hydrotreating process can lead to the degradation of olefins in the feed by converting them to saturated hydrocarbons by hydrogenation. This degradation of olefins by hydrogenation is usually undesirable because: (1) it leads to the consumption of expensive hydrogen, and (2) the Olefins are usually valuable as high octane components of gasoline. For example, a typical naphtha with the gasoline boiling range from a catalytic cracking process has a relatively high octane number as a result of a large content of olefins. Hydrotreating such a material causes a reduction in the olefin content in addition to the desired desulfurization, and the octane rating of the hydrotreating product decreases as the desulfurization intensity increases.

The U.S. Patent No. 5,865,988 (Collins et al.) Relates to a two-step process for the production of low sulfur gasoline from a olefinic, cracked, sulphurous naphtha. The procedure comprising: (1) passing the naphtha over a shape-selective acidic Catalyst such as ZSM-5 zeolite to selectively lower paraffins Octane to crack and some of the olefins and naphthenes to aromatic Convert compounds and aromatic side chains; and (2) Desulphurizing the resulting product over a hydrotreating catalyst in the presence of hydrogen. It is revealed that the initial treatment removed the olefins with the shape-selective acid catalyst, which otherwise saturate in the hydrodesulfurization step would.

The International Patent Application No. WO 98/30655 (Huff et al.) under the Patent Cooperation Treaty, reveals a procedure for Production of a product with reduced sulfur content from a Feedstock, wherein the feedstock is a mixture of hydrocarbons includes and organic sulfur compounds as undesirable impurities contains. This method involves converting at least a portion the sulfur-containing impurities to sulfur-containing products with a higher one Boiling point by treatment with an alkylating agent in the presence of an acid catalyst and removing at least part of these high boiling products by fractionation based on the boiling point.

The U.S. Patent Nos. 5,298,150 (Fletcher et al.); 5,346,609 (Fletcher et al.); 5,391,288 (Collins et al.) And 5,409,596 (Fletcher et al.). all relate to a two-step process for the production of a gasoline low sulfur content, with a naphtha feed of a Hydrodesulfurization is followed, followed by a treatment with a shape-selective catalyst to the octane, dias during the Hydrodesulfurization step has been lost to restore.

The U.S. Patent No. 5,171,916 (Le et al.) Relates to a method of upgrading a light return oil by: (1) Alkylating the heteroatom-containing aromatic compounds of the return oil with an aliphatic Hydrocarbon having at least one olefinic double bond by the use of a crystalline metal silicate catalyst; and (2) separating the high boiling alkylation product by fractionated ones Distillation. It is revealed that the unconverted light Return oil one having reduced sulfur and nitrogen content and that the high-boiling alkylation product is useful as a synthetic, alkylated, aromatic, functional, fluid starting material.

The U.S. Patent No. 5,599,441 (Collins et al.) Discloses a method for the removal of thiophene sulfur compounds from a cracked Naphtha by: (1) contacting the naphtha with an acid catalyst in an alkylation zone to alkylate the thiophene compounds, wherein the olefins present in the naphtha are used as an alkylating agent be used; (2) removing an effluent stream from the alkylation zone; and (3) separating the alkylated thiophene compounds from the effluent stream the alkylation zone by fractional distillation. It will also revealed that the high-sulfur fraction rich in sulfur fractionated the fractionated Distillation can be desulfurized using conventional Hydrotreating or other desulphurization process.

The U.S. Patent No. 5,863,419 (Huff, Jr. et al.) Discloses a catalytic Distillation process for the production of a product with reduced Sulfur content from a feedstock, wherein the feedstock a mixture of hydrocarbons, the organic sulfur compounds as undesirable impurities contain. The method involves performing the following method steps simultaneously Within a distillation column reactor: (1) Convert from at least part of the sulfur-containing impurities to sulfur-containing Products with higher Boiling point by treating with an alkylating agent in the presence an acid catalyst; and (2) removing at least a portion of said high boiling Products by fractional distillation. It is also revealed that the sulfur-rich high-boiling fraction is effective for a hydrotreating treatment at a relatively low cost, since its volume relative to the original one Feedstock is reduced.

More recently, U.S. Patent No. 6,024,865, issued to Bruce D. Alexander, George A. Huff, Vivek R. Pradhan, William J. Reagan, and Roger H. Cayton, disclosed a reduced sulfur product. which is made from a feed comprising a mixture of hydrocarbons containing sulfur-containing aromatic compounds as undesirable impurities. The process involves separating the feed by fractional distillation into a lower boiling fraction containing the more volatile sulfur-containing aromatic impurities and at least one higher boiling fraction containing the less volatile sulfur-containing aromatic impurities. Each fraction is then separately exposed to reaction conditions effective to convert at least part of its content of sulfur-containing aromatic impurities to higher-boiling sulfur-containing products by alkylation with an alkylating agent in the presence of an acidic catalyst. The higher-boiling sulfur-containing products are removed by fractional distillation. It is also stated that alkylation can be achieved in stages, provided that the conditions of the alkylation are less in the initial alkylation stage than in the second stage, e.g. By using a lower temperature in the first stage than a higher temperature in a second stage.

The U.S. Patent No. 6,059,962 to Bruce D. Alexander, George A. Huff, Vivek R. Pradhan, William J. Reagan and Roger H. Clayton discloses a product with reduced sulfur content, wherein the product is produced in a multi-stage process from a feedstock, which comprises a mixture of hydrocarbons and sulfur-containing contains aromatic compounds as undesirable impurities. The First stage involves: (1) subjecting the feedstock those alkylating conditions which are effective for conversion a portion of the impurities to higher-boiling sulfur-containing Products, and (2) separating the resulting products fractional distillation into a lower boiling fraction and a higher boiling Fraction. The lower boiling fraction includes hydrocarbons and has a reduced sulfur content compared to the Feedstock on. The higher boiling Fraction includes hydrocarbons and contains converted sulfur-containing aromatic impurities and also the higher-boiling sulfur-containing Products. Each of the subsequent stages includes: (1) undergoing the higher-boiling Fraction from the previous stage of such alkylation conditions, which are effective for a conversion of at least part of their content of sulfur-containing aromatic Compounds to higher boiling sulfur-containing products, and (2) separating the resulting Products by fractional distillation in a lower boiling Hydrocarbon fraction and a higher-boiling fraction, which heavies containing sulfur-containing alkylation products. The total hydrocarbon product with reduced sulfur content from the process comprises the lower boiling fractions from numerous stages.

One Another approach to reducing the content of sulfur-containing organic contaminants of a feedstock that is a normally liquid A mixture of hydrocarbons which includes olefins is in the International Publication No. WO 01/53432 A1. This approach includes (a) a Contacting the feedstock with an olefin modification catalyst in an olefin modification reaction zone under conditions are effective to produce a product having a bromine number, the less than that of the feed; (b) fractionation of the product from the olefin modification reaction zone for preparation of: (ii) a first fraction, the sulfur-containing organic Contains impurities and has a distillation endpoint, in the range of about 135 ° C to approximately 221 ° C is; and (ii) a second fraction that is heavier than the first Comprising fraction and sulfur-containing organic impurities; and (c) contacting the first fraction with a hydrodesulfurization catalyst in the presence of hydrogen in a hydrodesulfurization reaction zone under conditions that are effective for a conversion of at least a part of the sulfur in the sulphurous impurities the first fraction to hydrogen sulphide.

It has now been discovered that the sulfur-containing organic contaminants, while undergoing conversion in the olefin modification zone, form refractive sulfur compounds. The formation of these refractive compounds is undesirable because they can only be treated with conventional hydrodesulphurizers, resulting in a concomitant undesirable octane loss. These refractive sulfur compounds can not be removed via a selective hydrotreating process. It has also been discovered that these refractive sulfur compounds concentrate in the fraction of the olefin modification reaction zone product having a boiling range above about 200 ° C. The removal of these compounds can only be achieved by conventional hydrodesulfurization which leads to saturation of olefins and loss of octane. Also, trace amounts of olefin modification catalyst are leached from the catalyst in the olefin modification reaction zone and passed into the olefin modification zone product. These compounds or components containing the leached olefin modification catalyst have a potential to cause both catalyst deactivation and pressure drop in any downstream units such as one downstream hydrotreating unit. In addition, it has been discovered that these compounds, such as the refractive sulfur compounds, tend to concentrate in the fraction having the boiling point range of more than 200 ° C.

By Using the method of the present invention, the Problems related to the refractive sulfur compounds and the compounds or components, which leached olefin modification catalyst included, toned down are made by fractionation of the product from the olefin modification zone to at least three fractions. The advantage of splitting the Olefin modification zone product in at least three fractions that of the refractive compounds and the leached catalyst containing compounds or components in a relatively small Volume flow of the highest boiling Fraction of the olefin modification zone product can be recovered. Of the The remainder of the olefin modification zone product becomes at least two Divided fractions, with the lowest-boiling fraction relative is desulfurized and fed directly to a gasoline pool can, and the middle-boiling fraction can be a selective hydrotreating zone supplied be maintained, the octane number is maintained, while the sulfur-containing organic pollutants converted to hydrogen sulfide become. Although not preferred, alternatively Central fraction of a conventional hydrotreating plant and subsequently fed to a reformer to increase the octane of this fraction. According to the method of the invention For example, the major amount of olefin modification zone effluent, e.g. B. 90% by volume to 98% by volume, are separated into two fractions, the low in refractive sulfur and leached olefin modification catalyst and not an octane reducing hydrodesulfurization step be subjected.

The höchstsiedende Fraction can ideally be a conventional diesel or naphtha hydrotreating plant supplied be or back are passed to the fluidized catalytic cracking unit for one Removal of both refractive and nonrefractive Sulfur compounds. The leached olefin modification compounds or components can be over conventional Means known to those skilled in the art before a feed be removed to the activated aluminum hydrotreating system.

Summary the invention

Hydrocarbon liquids, which at standard printing over either a wide or a narrow range of temperatures boiling within a range of about 10 ° C to about 345 ° C are referred to herein as "hydrocarbon liquids". Such liquids are common in the refining of crude oil and also in the refining of products from a coal liquefaction and the processing of oil shale and tar sands involved, and these fluids typically comprise a complex mixture of hydrocarbons, and these mixtures can Paraffins, cycloparaffins, olefins and aromatic compounds lock in. For example, light naphtha, heavy naphtha, gasoline, kerosene and light return oil all hydrocarbon liquids.

Hydrocarbon liquids, which are involved in a refining, often contain undesirable sulfur-containing Impurities that must be at least partially removed. Hydrotreating are effective and usually for the removal of sulphurous impurities from hydrocarbon liquids used. Unfortunately are the conventional ones Hydrotreating usually unsatisfactory for one Use with high olefin hydrocarbon liquids such processes lead to significant conversion of the olefins Lead paraffins, which is usually low octane are. About that leads out the hydrogenation of olefins to a consumption of expensive hydrogen.

According to the International publication No. WO 01/53432 A1 organic sulfur compounds from hydrocarbon liquids be removed by a multi-step process, comprising: (a) a In contacting of the feedstock with an olefin modification reaction zone under conditions that are effective for producing a product having a bromine number less than that of the feedstock; (b) fractionating the product into two fractions: one first fraction with a distillation end point of 135 ° C to 221 ° C and a higher boiling Fraction; and (c) perform a hydrodesulfurization reaction with the lower boiling fraction.

Unfortunately, such a process results in undesirable octane loss since the first fraction is subjected to conventional hydrotreating which serves to reduce the octane via olefin saturation. In addition, such a procedure does not address the problems associated with the conversion of refractive sulfur compounds to hydrogen sulfide while maintaining the octane or provides solutions for it. Further, such a process does not address the difficulties encountered downstream of the olefin modification zone by the leached catalyst compounds or components, such as increased pressure drop and catalyst deactivation in downstream units.

consequently there is a need for a process that involves substantially complete removal of sulfur-containing Impurities from olefin-containing hydrocarbon liquids achieves which: (1) is relatively inexpensive to carry out, (2) if any, leads to a low octane loss; and (3) the problems associated with refractive sulfur compounds and leached catalyst compounds or components. For example, there is a need for such a method that uses can be used to remove sulfur-containing contaminants from hydrocarbon liquids such as products from a fluidized catalytic cracking process, which have a high olefin content and relatively large amounts Sulfur-containing organic materials such as mercaptans, thiophene compounds and benzothiophene compounds as undesirable impurities.

It it has now been found that such an improved procedure modifying the olefin content of the feed over one Olefin modification catalyst in an olefin modification step Fractionating the products from the olefin modification step at least three fractions based on boiling point, one selective Hydrotreating with boiling fraction and desulphurisation the highest boiling of the resulting fractions. The olefin modification step leads to a reduction in the olefinic unsaturation of the feedstock, which can be measured by the bromine number. As a consequence of the Olefin modification step is made from the subsequent selective Hydrotreating step obtained a low-sulfur product, the one low loss of octane with respect to the feed of the olefin modification step having. About that leads out the reduction of olefinic unsaturation in the olefin modification step to a corresponding reduction of hydrogen consumption in the corresponding selective hydrotreating step and hydrodesulfurization step, because there is a reduced number of olefinic double bonds is that consume hydrogen in hydrogenation reactions.

• (a) In-Kontakt-Bringen des Einsatzmaterials mit einem Olefinmodifikationskatalysator in einer Olefinmodifikationsreaktionszone unter Bedingungen, die wirksam sind, um ein Produkt mit einer Bromzahl herzustellen, die geringer als die des Einsatzmaterials ist;
• (b) Fraktionieren des Produkts aus der Olefinmodifikationsreaktionszone zur Herstellung:
• (i) einer ersten Fraktion, die schwefelhaltige organische Verunreinigungen umfasst und einen Destillationsendpunkt aufweist, der geringer als ungefähr 140 °C ist;
• (ii) einer zweiten Fraktion, die höher siedet als die erste Fraktion, welche schwefelhaltige organische Verunreinigungen umfasst und einen Destillationsendpunkt aufweist, der geringer als ungefähr 240 °C ist; und
• (iii) einer dritten Fraktion, die höher siedet als die zweite Fraktion und schwefelhaltige organische Verunreinigungen und refraktive Schwefelverbindungen umfasst;
• (c) In-Kontakt-Bringen der zweiten Fraktion mit einem selektiven Hydrotreatingkatalysator in der Gegenwart von Wasserstoff in einer selektiven Hydrotreatingreaktionszone unter Bedingungen, die wirksam sind, um zumindest einen Teil des Schwefels in den schwefelhaltigen Verunreinigungen der zweiten Fraktion zu Schwefelwasserstoff umzuwandeln; und
• (d) In-Kontakt-Bringen der dritten Fraktion mit einem Hydroentschwefelungskatalysator in der Gegenwart von Wasserstoff in einer Hydroentschwefelungsreaktionszone unter Bedingungen, die wirksam sind, um zumindest einen Teil des Schwefels in den schwefelhaltigen Verunreinigungen der dritten Fraktion zu Schwefelwasserstoff umzuwandeln.

One embodiment of the invention is a process for producing a reduced sulfur product from a feedstock, wherein the feedstock contains sulfur-containing organic contaminants and comprises a normally liquid mixture of hydrocarbons including olefins, the process comprising:

• (a) contacting the feedstock with an olefin modification catalyst in an olefin modification reaction zone under conditions effective to produce a product having a bromine number less than that of the feedstock;
• (b) fractionating the product from the olefin modification reaction zone to produce:
• (i) a first fraction comprising sulfur-containing organic contaminants and having a distillation endpoint less than about 140 ° C;
• (ii) a second fraction boiling higher than the first fraction comprising sulfur-containing organic contaminants and having a distillation endpoint less than about 240 ° C; and
• (iii) a third fraction boiling higher than the second fraction and comprising sulfur-containing organic impurities and refractive sulfur compounds;
• (c) contacting the second fraction with a selective hydrotreating catalyst in the presence of hydrogen in a selective hydrotreating reaction zone under conditions effective to convert at least a portion of the sulfur in the sulfur-containing impurities of the second fraction to hydrogen sulfide; and
• (d) contacting the third fraction with a hydrodesulfurization catalyst in the presence of hydrogen in a hydrodesulfurization reaction zone under conditions effective to convert at least a portion of the sulfur in the sulfur-containing impurities of the third fraction to hydrogen sulfide.

• (a) In-Kontakt-Bringen des Einsatzmaterials mit einem Olefinmodifikationskatalysator in einer Olefinmodifikationsreaktionszone unter Bedingungen, die wirksam sind, um ein Produkt mit einer Bromzahl herzustellen, die geringer als die des Einsatzmaterials ist, wobei der Olefinmodifikationskatalysator ein Säurekatalysator ist;
• (b) Fraktionieren des Produkts aus der Olefinmodifikationsreaktionszone zur Herstellung:
• (i) einer ersten Fraktion, die schwefelhaltige organische Verunreinigungen umfasst und einen Destillationsendpunkt aufweist, der geringer als ungefähr 120 °C ist;
• (ii) einer zweiten Fraktion, die höher siedet als die erste Fraktion, welche schwefelhaltige organische Verunreinigungen umfasst und einen Destillationsendpunkt aufweist, der geringer als ungefähr 200 °C ist; und
• (iii) einer dritten Fraktion, die höher siedet als die zweite Fraktion und schwefelhaltige organische Verunreinigungen und refraktive Schwefelverbindungen umfasst;
• (c) In-Kontakt-Bringen der zweiten Fraktion mit einem selektiven Hydrotreatingkatalysator in der Gegenwart von Wasserstoff in einer selektiven Hydrotreatingreaktionszone unter Bedingungen, die wirksam sind, um zumindest einen Teil des Schwefels in den schwefelhaltigen Verunreinigungen der zweiten Fraktion zu Schwefelwasserstoff umzuwandeln; und
• (d) In-Kontakt-Bringen der dritten Fraktion mit einem Hydroentschwefelungskatalysator in der Gegenwart von Wasserstoff in einer Hydroentschwefelungsreaktionszone unter Bedingungen, die wirksam sind, um zumindest einen Teil des Schwefels in den schwefelhaltigen Verunreinigungen der dritten Fraktion zu Schwefelwasserstoff umzuwandeln.

Another embodiment of the invention is a process for producing reduced sulfur products from a feedstock, wherein the feedstock contains sulfur-containing organic contaminants and comprises a normally liquid mixture of hydrocarbons including olefins, the process comprising:

• (a) contacting the feedstock with an olefin modification catalyst in an olefin modification reaction zone under conditions effective to produce a product having a bromine number lower than that of the feedstock, the olefin modification catalyst being an acid catalyst;
• (b) fractionating the product from the olefin modification reaction zone to produce:
• (i) a first fraction comprising sulfur-containing organic contaminants having a distillation endpoint less than about 120 ° C;
• (ii) a second fraction boiling higher than the first fraction comprising sulfur-containing organic contaminants and having a distillation endpoint less than about 200 ° C; and
• (iii) a third fraction boiling higher than the second fraction and comprising sulfur-containing organic impurities and refractive sulfur compounds;
• (c) contacting the second fraction with a selective hydrotreating catalyst in the presence of hydrogen in a selective hydrotreating reaction zone under conditions effective to convert at least a portion of the sulfur in the sulfur-containing impurities of the second fraction to hydrogen sulfide; and
• (d) contacting the third fraction with a hydrodesulfurization catalyst in the presence of hydrogen in a hydrodesulfurization reaction zone under conditions effective to convert at least a portion of the sulfur in the sulfur-containing impurities of the third fraction to hydrogen sulfide.

In a further embodiment Although not preferred, the second fraction may be one Supplied hydrodesulfurization zone followed by a reforming zone to the octane number of Fraction reduced in the hydrodesulfurization zone, to increase.

One The object of the invention is an improved method for removal sulfur-containing impurities from a hydrocarbon liquid, which contains a significant olefin content available put.

A Another object of the invention is an improved method for effective removal of sulphurous contaminants to provide an olefinic cracked naphtha.

A Another object of the invention is an improved method for the desulfurization of an olefinic cracked naphtha which is a product with essentially unchanged Octane yields.

Yet Another object of the invention is an improved method for the Dealing with problems related to refractive sulfur compounds and leached catalyst compounds or components in one Process for the removal of sulphurous impurities in a hydrocarbon liquid to disposal to deliver.

Short description the drawing

The Drawing is a schematic representation of an embodiment the invention.

Full Description of the invention

It has been a process for producing a product with reduced Sulfur content of an olefin-containing hydrocarbon distillate liquid, which contains sulfur-containing impurities discovered. The procedure can be used to make a product that is essentially is free of sulphurous impurities, a reduced Has olefin content and has an octane, similar to the of the feedstock.

The invention involves contacting the feedstock with an olefin modification catalyst in a reaction zone under conditions effective to produce an intermediate having a reduced amount of olefinic unsaturation relative to that of the feedstock as measured by the bromine number. The intermediate is then separated into at least three fractions of differing volatility. The highest volatility fraction (ie, the lowest boiling fraction) is relatively free of sulfur-containing organic contaminants, ie, generally below 20 ppm by weight of sulfur, and therefore can be fed directly to the gasoline pool. The second fraction or mid-range fraction is contacted with a selective hydrotreating catalyst in the presence of hydrogen under conditions effective to convert at least a portion of its sulfur-containing organic contaminants to hydrogen sulfide. The hydrogen sulfide can be readily removed by conventional methods to produce a product having substantially reduced sulfur content relative to the feeds. The third fraction or highest boiling frak tion is contacted with a hydrodesulfurization catalyst in the presence of hydrogen under conditions effective to convert at least a portion of the sulfur-containing organic contaminants and the refractive sulfur compounds to hydrogen sulfide. The hydrogen sulfide can be easily removed by conventional methods to provide a product with significantly reduced sulfur content relative to the feeds.

aromatic Sulfur-containing impurities in the feedstock, such as thiophene compounds and Benzothiophene compounds are subject to within the olefin modification cation zone at least partially a conversion to higher-boiling sulfur-containing Products, some of which are called refractive sulfur compounds, which will be further defined below can. It is believed that this transformation is a result of alkylation of the aromatic sulphurous impurities by olefins which is catalyzed by the olefin modification catalyst. After fractionating the effluent from the olefin modification reaction zone Most of these high-boiling sulfur-containing materials appear including the refractive sulfur compounds, in the third boiling fraction or highest boiling Fraction, and the first or lower boiling fraction and the medium-boiling fraction have a reduced sulfur content relative to that of the feedstock to the olefin modification zone on.

In one to a great extent preferred embodiment the second fraction is brought into contact with a selective fraction Hydrotreating catalyst in the presence of oxygen under conditions which are effective to at least part of the sulfur-containing Convert impurities of the fraction to hydrogen sulphide. This can be done by using the selective hydrotreating method, currently licensed, such as the SCANfining process, the licensed from ExxonMobil Research and Engineering Company, and the PRIME-G + process licensed by IFP North America Inc. or by operating a conventional one Hydrotreating process under selective hydrotreating conditions, which, relatively speaking, are less strong, such that desulfurization in a limited olefin saturation takes place. Such selective hydrotreating methods are also disclosed in U.S. Patent No. 6,007,704 (Chapus et al.), in U.S. Patent No. 5,821,397 (Joly et al.) And U.S. Patent No. 6,255,548 (Didillon et al.).

The third fraction is contacted with a hydrodesulfurization catalyst in the presence of hydrogen under conditions that are effective are at least a portion of their sulfur-containing impurities, including refractive sulfur compounds to convert to hydrogen sulfide. One greater Proportion of sulphurous impurities of higher boiling Faction or factions become common aromatic sulfur-containing compounds such as thiophene compounds and benzothiophene compounds and refractive sulfur compounds, which are more difficult to remove by hydrodesulfurization than mercaptans and thiophene compounds. Accordingly, a preferred embodiment invention uses more vigorous hydrodesulfurization conditions include.

Feedstocks in the practical implementation of this invention normally comprise liquid Hydrocarbon mixtures containing olefins and a Boiling temperature range within the range of about 10 ° C to about 345 ° C, which was measured by the method ASTM D 2887-97a (found can be found in the 1999 Annual Book of ASTM Standards, section 5, Petroleum Products, Lubricants and Fossil Fuels, Vol. 05.02, p. 200, which method hereby by reference in its entirety is included) or by conventional alternative methods. About that In addition, suitable feedstocks are preferably a mixture from hydrocarbons, which are in the gasoline range boil. If desired, can such feeds also contain significant amounts of hydrocarbon components of less volatility keep a higher one Boiling point as the fraction with high volatility. The feedstock becomes a normally liquid A mixture of hydrocarbons which desirably has a distillation endpoint that is about 345 ° C or lower, and preferably approximately 249 ° C or is lower. Preferably, the feed becomes an initial boiling point which is below about 79 ° C, and having a distillation endpoint not higher than approximately 345 ° C is located. Suitable feedstocks include any of the numerous complex mixtures of hydrocarbons, which are commonly related to the refining of crude oil, such as natural gas liquids, Naphthas, light gas oils, heavy gas oils and widely blended gas oils, as well as hydrocarbon fractions resulting from coal liquefaction and the processing of oil shale or tar sands come. Preferred feedstocks include olefin-containing hydrocarbon blends, from catalytic cracking or coking of hydrocarbon feeds come.

catalytic Crackers are highly effective preferably as a source of feedstock hydrocarbons for one Use in the present invention. Materials of this type include liquids, the below about Boil at 345 ° C, such as light naphtha, heavy naphtha and light return oil. Understandably However, the entire output of volatile products can also be made from one catalytic cracking process as a source of feedstock hydrocarbons for one Use used in the practice of this invention become. Catalytic cracking products are a desirable source of feedstock hydrocarbons. since they typically have a relatively high olefin content and they usually significant amounts of organic sulfur compounds as impurities contain. For example, a light naphtha can be fluidized out of one catalytic cracking of a petroleum-derived gas oil up to approximately Contain 60% by weight of olefins and up to about 0.7% by weight of sulfur, the majority sulfur in the form of thiophene compounds and benzothiophene compounds is present. About that In addition, the sulfur-containing impurities usually become Include mercaptans and organic sulfides. A preferred feedstock for one Use in the practice of this invention comprise catalytic cracking products and will be at least 1% by weight contained in olefins. A preferred feedstock will be hydrocarbons from a catalytic cracking process and will at least Contain 10 wt .-% of olefins. A highly preferred feedstock will include hydrocarbons from a catalytic cracking process and will be at least about Contain 15 wt .-% or 20 wt .-% of olefins.

In an embodiment In accordance with the invention, the feed of the invention will be a mixture from low molecular weight olefins with hydrocarbons from a catalytic cracking process. For example, can a feedstock can be prepared by adding olefins, which contain from 3 to 5 carbon atoms, to a naphtha from a catalytic cracking process.

In another embodiment In accordance with the invention, the feed of the invention will be a mixture from a naphtha from a catalytic cracking process with a Source of volatile aromatic compounds such as benzene and toluene. For example For example, a feed may be prepared by mixing a light reformate with a naphtha from a catalytic cracking process. A typical light reformate will be from about 0 to about 2% by volume. of olefins, from about 20 to 45 vol .-% of aromatic compounds and is have such distillation characteristics that the 10% distillation point ("T10") not higher than approximately 160 ° F (71 ° C), the 50% distillation point ("T50") is not higher than approximately 200 ° F (93 ° C) and the 90% distillation point ("T90") not higher as about 250 ° F (121 ° C). Of course, these distillation points refer to a distillation point, which according to the method ASTM D 86-97 (which can be found in the 1999 Annual Book of ASTM Standards, Section 5, Petroleum Products, Lubricants and Fossil Fuels, Vol. 05.01, p. 16, which method hereby by Reference in its entirety is included) or by conventional alternative procedures. A typical light reformat will be from approximately 5 to about Containing 15 vol .-% of benzene.

A another embodiment invention involves the use of a feedstock, a mixture of: (1) hydrocarbons from a catalytic Cracking process (2) a source of volatile aromatic compounds; and (3) a source of olefins having from 3 to 5 carbon atoms included.

suitable Feed materials for The invention will be at least 1% by weight of olefins, preferably at least 10% by weight of olefins and more preferably at least approximately Contain 15 wt .-% or 20 wt .-% of olefins. If desired, can the feedstock has an olefin content of 50% by weight or more. About that can out suitable feedstocks from about 0.005 wt.% to about 2.0 wt.% of sulfur in the form of organic sulfur compounds. However, typical feeds are generally 0.05 Wt% to about 0.7% by weight of sulfur in the form of organic sulfur compounds contain.

Feedstocks useful in the practice of this invention, such as naphtha from a catalytic cracking process, will sometimes contain nitrogen-containing organic compounds as impurities in addition to the sulfur-containing impurities. Many of the typical nitrogenous contaminants are organic bases and, in some cases, may cause relatively rapid deactivation of the olefin modification catalyst of the present invention. In the case where such deactivation is observed, it can be prevented by removing the basic nitrogen-containing impurities before they come in contact with the olefin-modification catalyst. When the feedstock contains basic nitrogen-containing impurities, accordingly a preferred embodiment of the invention comprises removing these basic nitrogen-containing impurities from the feed before it contacts the olefin-modification catalyst. In another embodiment of the invention, a feedstock substantially free of basic nitrogen-containing contaminants is used (for example, such feedstock will contain less than about 50 ppm by weight of basic nitrogen.) A highly desirable feedstock comprises a treated feedstock A naphtha prepared by removing basic nitrogen-containing impurities from a naphtha produced by a catalytic cracking process.

basic Nitrogen-containing impurities may be from the feedstock or of a material that acts as a feedstock component is to be used by any conventional method become. Such procedures typically involve treatment with an acidic material, and conventional methods include those Operations such as washing with an aqueous solution of an acid or passing the material through a guard bed. Furthermore For example, a combination of such methods may be used. guard beds can Materials include, but are not limited to, A zeolite, Y zeolite, L-zeolite, mordenite, fluorinated alumina, fresh cracking catalyst, Include equilibrium cracking catalyst and acidic polymer resins. If a shelter bed technique is used, it is often desirable to use two protective beds in such a way that one Protective bed can be regenerated while the other is in operation is. When to remove basic nitrogen-containing impurities a cracking catalyst is used, such a material can be used in Regenerator regenerated a catalytic cracking unit, when it comes to his ability has been deactivated to remove such contaminants. If an acid wash for removal of basic nitrogen-containing compounds is used, the treatment is carried out with an aqueous solution of a suitable acid. suitable acids for one Such uses include, but are not limited to, Hydrochloric acid, sulfuric acid and acetic acid. The concentration of acid in the aqueous solution is not critical but will suitably be in the range of about 0.1% by weight until about Chosen 30 wt .-%. For removal of basic nitrogen-containing impurities from a heavy naphtha produced by a catalytic cracking process For example, a solution containing 5% by weight of sulfuric acid in water may be prepared be used.

The Method of this invention is highly effective in removal Sulfur-containing organic contaminants of any type from the feed. Such impurities typically become aromatic, sulfur-containing, organic compounds which all aromatic organic compounds comprising at least contain a sulfur atom. Such materials include thiophene compounds and benzothiophene compounds, and examples of such materials include, but are not limited to to be thiophene, 2-methylthiophene, 3-methylthiophene, 2,3-dimethylthiophene, 2,5-dimethylthiophene, 2-ethyltiophene, 3-ethylthiophene, benzothiophene, 2-methylbenzothiophene, 2,3-dimethylbenzothiophene and 3-ethylbenzothiophene. Other typical sulfur-containing contaminants include mercaptans and organic sulfides and disulfides.

Of the Olefin modification catalyst of the invention may be any one of Include material that catalyzes the oligomerization of olefins be able to. Desirably For example, the olefin modification catalyst will comprise a material that also for the catalysis of the alkylation of aromatic organic compounds by means of olefins. Conventional alkylation catalysts are to a great extent suitable for a use as the olefin modification catalyst of this invention, because they typically have the ability for the catalysis of both an olefin oligomerization and the Alkylation of aromatic organic compounds by means of olefins exhibit. Although liquid acids like sulfuric acid can be used For example, solid acid catalysts are particularly desirable, and such solid acid catalysts include liquid acids, which are supported on a solid substrate. The solid catalysts are generally opposite liquid Catalysts due to the simplicity with which the feed is in contact can be brought with such a material, preferably. To the For example, the feed may be simply through one or more fixed beds made of solid particulate Catalyst can be passed at a suitable temperature. alternative for this, the feed may be through a bubbling bed of solid particulate catalyst be directed.

Olefin modification catalysts suitable for use in the practice of the invention may include materials such as acidic polymeric resins, supported acids, and acidic inorganic oxides. Suitable acidic polymer resins include the polymer sulfonic acid resins which are well known in the art and are commercially available. A typical example of such material is Amberlyst ^® 35, a product manufactured by Rohm and Haas Co..

Supported acids useful as olefin modification catalysts include, but are not limited to, Bronsted acids (examples include phosphoric acid, sulfuric acid, boric acid, HF, fluorosulfonic acid, trifluoromethanesulfonic acid and dihydroxyfluoroboric acid) and Lewis acids (examples include BF ₃ , BCl ₃ , AlCl ₃ , AlBr ₃ , FeCl ₂ , FeCl ₃ , ZnCl ₂ , SbF ₅ , SbCl ₅ and combinations of AlCl ₃ and HCl) supported on solids such as silica, alumina, silica-alumina, zirconia or clays. When supported liquid acids are used, the supported catalysts are typically prepared by combining the desired liquid acids with the desired support and drying. Supported catalysts prepared by combining a phosphoric acid with a support are highly preferred and are referred to herein as solid phosphoric acid catalysts. These catalysts are preferred because they are both highly effective and inexpensive. U.S. Patent No. 2,921,081 (Zimmerschied et al.), Which is hereby incorporated by reference in its entirety, discloses the preparation of solid phosphoric acid catalysts by combining a zirconium compound selected from the group consisting of zirconium oxide and halides of zirconium with an acid selected from the group consisting of orthophosphoric acid, pyrophosphoric acid and triphosphoric acid. U.S. Patent No. 2,120,702 (Ipatieff et al.), Which is incorporated herein by reference in its entirety, discloses the preparation of solid phosphoric acid catalysts by combining a phosphoric acid with a silicon-containing material. Finally, British Patent No. 863,539, which is hereby incorporated by reference in its entirety, also discloses the preparation of a solid phosphoric acid catalyst by depositing a phosphoric acid on a solid silicon-containing material, such as diatomaceous earth or kieselguhr.

Regarding one solid phosphoric acid, made by depositing a phosphoric acid on diatomaceous earth it is assumed that the catalyst contains: (1) one or more free phosphoric acids (such as orthophosphoric acid, pyrophosphoric acid and Triphosphoric) worn on diatomaceous earth; and (2) silicon phosphates, come from the chemical reaction of the acid or acids with the diatomaceous earth. While the anhydrous silicon phosphates as inactive as an olefin modification catalyst It is also believed that they are hydrolyzed can, to give a mixture of orthophosphoric acid and polyphosphoric acid, which is active as an olefin modification catalyst. The exact Composition of this mixture will depend on the amount of water, which the catalyst is exposed. To a solid Phosphorsäurealkylierungskatalysator maintain at a satisfactory level of activity, if this as an olefin modification catalyst with a substantially anhydrous Feedstock is used, it is common practice, a low Add an amount of an alcohol such as isopropyl alcohol to the feed, around the catalyst at a satisfactory hydration level to keep. It is believed that the alcohol is in contact subject to dehydration with the catalyst and that the resulting water then causes a hydration of the catalyst. If the catalyst contains too little water, it tends to be a very high activity to show which to a quick deactivation as a consequence a coking leads, and becomes the catalyst about it have no good physical integrity. Furthermore, serves a Hydration of the catalyst reduces its activity and decreases its tendency to rapid deactivation by coke formation. An excessive hydration However, such a catalyst can cause the catalyst softened, physically agglomerated and high pressure drops in fixed bed reactors generated. Accordingly, there is an optimal level of hydration for a solid phosphoric acid catalyst, and this level of hydration becomes a function of the reaction conditions be. Although the invention is not limited thereto, we have fixed phosphoric acid catalysts found that a water concentration in the feedstock, in the range of about 50 to about 1000 ppm by weight, is generally satisfactory Maintains level of catalyst hydration. If desired, can this water can be provided in the form of an alcohol such as isopropyl alcohol, which is believed to be in contact with the catalyst subject to dehydration.

Acid inorganic oxides which are used as olefin modification catalysts usable, include, but are not limited to, aluminas, Silica-aluminas, natural and synthetic pillared clays and natural and synthetic zeolites such as faujasites, mordenites, L-, omega-, X, Y, beta and ZSM zeolites. Include highly suitable zeolites beta, Y, ZSM-3, ZSM-4, ZSM-5, ZSM-18 and ZSM-20. If desired, the Zeolites in an inorganic oxide matrix material such as silica-alumina be introduced.

Olefin modification catalysts may comprise mixtures of various materials, such as a Lewis acid (examples include BF ₃ , BCl ₃ , SbF ₅ and AlCl ₃ ), a non-zeolitic solid inorganic oxide (such as silica, alumina and silica-alumina) and a large pore crystalline molecular sieve (Examples include zeolites, pillared clays and aluminum phosphates).

In in the case of using a solid olefin modification catalyst becomes desirable exist in a physical form, which is a fast and effective Contacting with the feed in the olefin modification reaction zone allowed. Although the invention is not limited thereto, it is preferred that a solid catalyst is in particulate form, where the largest dimension the particle has an average value in the range of about 0.1 mm until about 2 cm. For example, you can essentially spherical Beads of the catalyst used have a mean diameter from about 0.1 mm to about 2 cm. Alternatively, the catalyst may be in the mold of chopsticks with a diameter in the range of about 0.1 mm to about 1 cm and a length in the range of about 0.2 mm to about 2 cm can be used.

at the practical implementation The invention provides the feedstock with an olefin modification catalyst in an olefin modification reaction zone under conditions which are effective to produce a product having a bromine number, which is lower than that of the feedstock, without a significant Cracking any paraffins in the feed is caused. The "Bromine Number" on here It should be understood that it is preferred is determined by the method ASTM D 1159-98, which in the 1999 Annual Book of ASTM Standards, Section 5, Petroleum Products, Lubricants and Fossil Fuels, Vol. 05.01, p. 407, can be found and which method is hereby incorporated by reference in its entirety is recorded. It can but also other conventional ones analytical methods are used to determine the bromine number. The bromine number of the product from the olefin modification reaction zone becomes desirable not bigger than 80% of that of the feed to this reaction zone, preferably not larger than 70% of that of the feed, and most preferably not greater than 65% of that of the feed.

The Reaction zone may consist of one or more fixed bed reactors, containing the same or different catalysts. One Fixed bed reactor may include a variety of catalyst beds. The multitude of catalyst beds in a single fixed bed reactor may also comprise the same or different catalysts.

The conditions used in the olefin modification reaction zone are also preferably chosen that at least a portion of the olefins in the feed to products is converted, which have a suitable volatility, as Components of fuels such as gasoline and diesel fuels useful to be.

Even though the invention is not limited thereto, it is preferred that the olefins in the feed to the olefin modification reaction zone at least partially in a variety of chemical reactions when Contact of the feedstock with the olefin modification catalyst consumed in the zone. It is also believed that the specific chemical reactions of the composition of the Depend on the starting material become. It is believed that these chemical processes have a Olefin polymerization and the alkylation of aromatic compounds by olefins.

The Condensation reaction of an olefin or a mixture of olefins over one Olefin modification catalyst for the formation of products with higher Molecular weight is referred to herein as a polymerization process. and the products can either low molecular weight oligomers or polymers be of high molecular weight. Oligomers are made by the condensation of 2, 3 or 4 olefin molecules formed with each other while Polymers are formed by the condensation of 5 or more olefin molecules together. As used herein, the term "polymerization" is used in a width, which is a process for the formation of oligomers and / or polymers designated. An olefin polymerization results in consumption of olefinic unsaturation. For example, the simple condensation of two molecules of propene results in the formation of an olefin with six carbons, which only has a single olefinic double bond (2 double bonds in the starting materials were replaced by 1 double bond in the product). equally results in the simple condensation of three molecules of propene in the formation of an olefin with nine carbons, which only has a single olefinic double bond (3 double bonds in the starting materials were replaced by 1 double bond in the product).

Although olefin polymerization is a simple model for understanding the reduction in bromine number that takes place in the olefin modification reaction zone, it is believed that other processes are significant as well. For example, the initial products of a simple olefin condensation may undergo isomerization in the presence of the olefin modification catalyst to yield highly branched monounsaturated olefins. In addition, polymerization reactions can take place to give polymers which subsequently undergo fragmentation in the presence of the olefin modification catalyst to yield highly branched products having a lower molecular weight than the initial polymerization product. Although not limited thereto, it is believed that the following transformations take place within the olefin modification reaction zone: (1) olefins in the feedstock having low molecular weight are converted to higher molecular weight olefins which are both highly branched and within the range Boiling range of gasoline; and (2) straight or low branched olefins in the feedstock are isomerized to highly branched olefins which are within the boiling range of gasoline.

The Alkylation of aromatic compounds is also important chemical process occurring in the olefin modification reaction zone can take place and reduce the bromine number of the feedstock contributes. The alkylation of an aromatic organic compound by means of an olefin containing a single double bond leads to destruction the double bond of the olefin and leads to the substitution of a Alkyl group for a hydrogen atom on the aromatic ring system of the substrate. This destruction The olefinic double bond of the olefin contributes to the formation of a product in the olefin modification reaction zone, which reduced one Bromine number relative to that of the feedstock. aromatic However, organic compounds vary widely in theirs Reactivity as alkylating substrates. The relative reactivities of some representative aromatic compounds over a Alkylation by means of 1-heptene at 204 ° C over a solid phosphoric acid catalyst are shown, for example, in Table I, where each rate constant derived from the slope of a line that was obtained by plotting experimental data in the form In (1 - x) as a function of time, where x is the substrate concentration.

As As used herein, the term "sulfur-containing aromatic compound" and "sulfur-containing aromatic Pollution "one any aromatic organic compound containing at least one Contains sulfur atom in its atomatic ring system. Such Close materials Thiophene compounds and benzothiophene compounds.

sulfuric aromatic compounds are usually alkylated much faster than aromatic hydrocarbons. consequently can the sulphurous aromatic impurities up to a certain Degree selectively alkylated in the olefin modification reaction zone become. If desired, can, however the reaction conditions in the reaction zone are chosen so that a significant alkylation of aromatic hydrocarbons takes place. This embodiment The invention can be very useful when the feedstock volatile contains aromatic hydrocarbons such as benzene and it is desirable such material by conversion to higher molecular weight alkylation products. These embodiment is particularly useful when the feedstock contains significant amounts Low molecular weight olefins, such as olefins, include those of 3 contain up to 5 carbon atoms. The products of a mono or Dialkylation of benzene with such low molecular weight olefins will contain from 9 to 16 carbon atoms and will be sufficient accordingly volatile be in order as components for Gasoline or diesel fuels to be useful.

TABLE I. Alkylation rate constants for various aromatic substrates when reacted with 1-heptene at 204 ° C over a solid phosphoric acid catalyst.

The alkylation of sulfur-containing aromatic impurities in the feed to the olefin modification reaction zone results in the formation of higher boiling sulfur-containing products. Accordingly, such materials can be removed by fractionation of the reaction zone effluent based on the boiling point. As a very rough approximation, each carbon atom in the side chain of a monoalkylated thiophene adds about 25 ° C to the boiling point of thiophene of 84 ° C. For example, 2-octylthiophene has a boiling point of 259 ° C, which corresponds to a boiling point increase of 23 ° C which corresponds to thiophene for each carbon atom in the eight carbon alkyl group. Accordingly, monoalkylation of thiophene with a C ₇ -C ₁₅ olefin in the olefin modification reaction zone will usually yield a sulfur-containing alkylation product having a sufficiently high boiling point to be easily fractionated by distillation as a component of a high boiling fraction having an initial boiling point of about 210 ° C, to be removed.

The Alkylation of a sulfur-containing aromatic compound by means An olefin is obtained by the monoalkylation of thiophene with propene to either 2-isopropylthiophene or 3-isopropylthiophene to surrender. The higher one Molecular weight of such alkylation product reflects reflected in a higher Boiling point relative to that of the starting material. In one embodiment In the invention, the reaction conditions in the olefin modification reaction zone chosen so that a major part of any sulfur-containing aromatic Impurities in the feed to higher-boiling sulfur-containing Products is converted.

mercaptans are a class of organic sulfur compounds, the common in significant amount as impurities in hydrocarbon liquids turn up, which usually related to the refining of crude oil. For example Straight-run gasolines, which are produced by simple distillation of crude oil be, often significant amounts of mercaptans and sulfides as impurities contain. About that In addition, benzothiophene compounds and some are multisubstituted Thiophenes, like certain 2,5-dialkylthiophenes, are also relatively unreactive under the conditions used in the olefin modification reaction zone be. Accordingly, a greater Proportion of mercaptans in the feedstock and significant amounts certain relatively unreactive sulfur-containing aromatic compounds survive the reaction conditions in the olefin modification reaction zone.

at the practical implementation of this invention, the feedstock is brought into contact with the Olefin modification catalyst within the olefin modification reaction zone at a temperature and above a period of time which are effective to achieve the desired reduction in olefinic Unsatisfaction of the Feedstock, which is measured by means of the bromine number, too result. The contact temperature is desirably above about 50 ° C, preferably above 100 ° C and at most preferred over 125 ° C lie. The contact is generally at a temperature in the range of about 50 ° C to about 350 ° C, preferably of about 100 ° C to approximately 350 ° C and more preferably about 125 ° C to about 250 ° C performed. It However, it will obviously appear that the optimum temperature a function of the olefin modification catalyst used, the Olefin concentration in the feedstock, the nature of the feedstock present olefins and the nature of the aromatic compounds in the Feedstock to be alkylated will be.

The Feedstock may be reacted with the olefin modification catalyst in the Olefin modification reaction zone at any suitable Pressure be brought into contact. However, there are pressures in the range of approximately 0.01 to about 200 atmospheres desirable, and a pressure in the range of about 1 to about 100 atmospheres prefers. If the feedstock is easily made possible by a catalyst bed to flow, For example, it is generally preferable to use a pressure in which the feed be liquid becomes.

In one to a great extent preferred embodiment of the invention are those in the olefin modification reaction zone used conditions chosen so that no significant cracking of paraffins in the feed takes place. For example, desirably less Cracked as 10% of the paraffins in the feed are preferably less than 5% of the paraffins are cracked and are more preferred less than 1% of the paraffins cracked. It is believed that a significant cracking of paraffins in the formation of undesirable By-products result, for example, the formation of compounds with low molecular weight, resulting in a volume loss of Gasoline results.

at the practical implementation the invention becomes the effluent from the olefin modification reaction zone on the basis of volatility fractionated into at least three fractions.

Of the Distillation start boiling point of the highest boiling third fraction is desirably greater than approximately 200 ° C.

This fraction will contain a concentration of various compounds which can cause rapid catalyst deactivation in downstream selective and conventional hydrotreating plants. Specifically, in the olefin modification reaction zone, refractive sulfur species become it testifies. These refractive sulfur compounds concentrate in the fraction 200 ° C plus the olefin modification zone product. The removal of these compounds can be accomplished via conventional hydrotreating or hydrodesulfurization which also adversely results in saturation of olefins causing octane loss.

It is believed that these refractive sulfur compounds have the following structure:

In this case, R2 and R1 must have two or more carbons, z. C ₂ H ₅ , C ₃ H ₇ , etc., and one must have more than five carbons, e.g. B. C ₅ H ₁₁ , C ₆ H ₁₃ , etc.

Thus, examples of refractive sulfur compounds are the following:

It It is believed that refractive sulfur is a thiophene that contains seven or more alkyl carbons.

In the olefin modification zone additionally Trace amounts of the olefin modification catalyst are leached and enter the olefin modification zone product. This leached Catalyst may have difficulty in catalyst deactivation and / or a pressure drop in any downstream selective hydrotreating plant or a hydrodesulfurization reactor cause. This leaked catalyst tends to get into the boiling fraction 200 ° C plus to concentrate.

Other undesirable Compounds that concentrate in the 200 ° C plus boiling range fraction include nitrogenous ones Connections and serve.

Of the Advantage of the method of the invention is that these compounds in the relatively small volume of the fraction 200 ° C plus recovered can be. The volume of this fraction can be from 2% by volume to 10% by volume of the Olefin modification zone product. Preferably, this can percent volume fraction ranging from 2% by volume to 6% by volume.

Consequently can the total amount, z. B. 90-98 Vol .-%, of the olefin modification product divided into two fractions become. The first or lowest boiling fraction with a boiling point range of 140 ° C minus or more preferably 120 ° C minus can be fed directly to the gasoline. The lowest boiling The first fraction is typically as free of sulfur as that she less than about 50 ppm by weight of sulfur and preferably less than 30 ppm by weight of sulfur, and most preferably less than 20 ppm contains weight, and therefore can be used directly as a starting material for the mixture of Gasoline to be used.

The Mid-fraction or second boiling fraction preferably has one Distillation endpoint of less than about 240 ° C, and most preferably of less than about 200 ° C. The second or middle-boiling fraction becomes a selective one Hydrotreating zone, the sulfur compounds while maintaining removed from the octane.

The highest boiling fraction, having a boiling range higher than that of the mid-fraction, from the fractionation of the product from the olefin modification reaction zone is contacted with a hydrodesulfurization catalyst in the presence of hydrogen under conditions effective to contain at least a portion of the sulfur in their sulfur-containing organic impurities, including the refractive sulfur compounds, to convert to hydrogen sulphide. In a highly preferred embodiment, at least a portion of the higher boiling fraction or fractions will also be treated with a hydrodesulfurization catalyst in the presence of hydrogen under conditions which are effective to convert at least a portion of the sulfur in their sulfur-containing organic impurities to hydrogen sulphide. Alternatively, the highest boiling fraction may be recycled to the fluidized catalytic cracking unit.

Of the Hydrodesulfurization catalyst may be any conventional one Catalyst, for example, a catalyst containing a metal of Group VI and / or Group VIII, which is based on a suitable Substrate is worn. The Group VI metal is typical molybdenum or tungsten, and the Group VIII metal is typical Nickel or cobalt. Typical combinations include nickel with molybdenum and cobalt with molybdenum one. Suitable catalyst carriers include without limitation alumina, silica, titania, calcia, Magnesium oxide, strontium oxide, barium oxide, carbon, zirconium oxide, Diatomaceous earth and lanthanide oxides. Preferred catalyst supports are porous and shut down Alumina, silica and silica-alumina.

The Particle size and shape of the hydrodesulfurization catalyst is typically characterized by Determined manner in which the reactants with the catalyst be brought into contact. For example, the catalyst may be as a fixed bed catalyst or used as a bubbling bed catalyst become.

The Hydrodesulfurization reaction conditions used in the practical execution used in this invention are of conventional character. The pressure can be, for example, about 15 to about 1500 psi (approx 1.02 to about 102.1 atmospheres) pass; the temperature can range from about 50 ° C to about 450 ° C and the liquid hourly space velocity can be about 0.5 until about 15 LHSV are enough. The relationship from hydrogen to hydrocarbon feed in the hydrodesulfurization reaction zone is typically around 200 to about 5000 standard cubic feet per barrel pass. The extent of Hydrodesulfurization becomes a function of the hydrodesulfurization catalyst and the chosen one Reaction conditions and also the exact nature of the sulfur-containing organic impurities in the feed to the hydrodesulfurization reaction zone be. The process conditions of hydrodesulfurization become desirable chosen so that at least about 50% of the sulfur content of the sulfur-containing organic impurities be converted to hydrogen sulfide, and preferably such that the conversion to hydrogen sulphide is at least about 75% or more.

To The removal of hydrogen sulphide becomes the product of hydrodesulphurisation the highest boiling Fraction from the olefin modification reaction zone a sulfur content desirably less than 50 ppm by weight, preferably less than 30 ppm by weight and more preferably less than 10 ppm by weight. The Octane of this hydrodesulfurization product is desirably at least 90% of that of the feedstock to the olefin modification reaction zone be, preferably at least 95% of that of the feedstock and more preferably at least 97% of that of the feedstock. Unless otherwise specified, the term octane refers to as as used herein, an (R + M) / 2-octane which is the sum of a materials research octane and an engine octane divided by 2 is.

The medium-boiling second fractionation product of the effluent the olefin modification reaction zone is contacted with a selective hydrotreating catalyst in the presence of hydrogen under conditions that are effective to selectively at least one Part of the sulfur in its sulfurous organic impurities to convert hydrogen sulfide with minimal hydrogenation from olefins.

Such a selective hydrotreating process, referred to as SCANfining ^™ , is licensed from ExxonMobil Research and Engineering Company. The SCANfining process is a catalytic desulfurization process which uses a catalyst called RT 225 to selectively remove fluidized catalytic cracking naphtha sulfur with minimal hydrogenation of olefins, thereby preserving octane. Another selective hydrotreating process is referred to as PRIME-G + ^™ and licensed by IFP North America, Inc. This process allows more than 98% desulfurization of FCC naphtha, while octane is maximized by limited olefin saturation. Another method of effecting the selective hydrotreating process according to the process of the present invention is to contact the intermediate boiling second fraction with a conventional hydrotreating catalyst at selective hydrotreating zone conditions, which are generally less severe or milder than conventional hydrotreating conditions. The selective hydrotreating zone conditions include a temperature in the range of about 100 ° C to about 300 ° C, a pressure range of about 300 psig to about 600 psig, and a liquid hourly space velocity in the range of about 3 to about 10. The hydrogen to hydrocarbon feed ratio in the selective hydrotreating zone will range from about 700 to about 2,000 standard cubic feet per barrel of feed.

To performing the selective hydrotreating step and the removal of hydrogen sulfide the medium-boiling fraction will have a sulfur content, desirably less than about 50 ppm by weight, preferably less than 30 ppm by weight and more preferably less than 10 ppm by weight. The octane of this The middle fraction of the selective hydrotreating process is desirably at least 95% of that of the feedstock to the olefin modification zone preferably at least 97% and most preferably 98% of that of the corresponding feedstock.

An embodiment of the invention is shown schematically in the drawing. Referring to the drawing, all of the catalytic naphtha from a fluidized catalytic cracking process is passed through the conduit 1 in the pretreatment vessel 2 directed. The naphtha feedstock comprises a mixture of hydrocarbons including olefins, paraffins, naphthenes, and aromatic compounds, and the olefin content ranges from about 10% to about 60% by weight. In addition, the naphtha feedstock contains from about 0.2% to about 0.5% by weight of sulfur in the form of sulfur-containing organic contaminants including thiophene, thiophene derivatives, benzothiophene and benzothiophene derivatives, mercaptans, sulfides and disulfides. The feedstock also contains from about 5 to about 200 ppm by weight of basic nitrogenous contaminants.

The basic nitrogenous contaminants are from the feed in the pretreatment vessel 2 removed by contact with an acidic material such as an aqueous solution of sulfuric acid under mild contacting conditions that do not cause any significant chemical modification of the hydrocarbon components of the feedstock.

The effluent from the pre-treatment vessel 2 is through the line 3 and in the olefin modification reactor 4 passed, which contains an olefin modification catalyst. The feed to the reactor 4 is passed through the reactor where it contacts the olefin modification catalyst under reaction conditions effective to produce a product having a bromine number less than that of the feed from the conduit 3 , In addition, a significant portion of the thiophene and benzothiophene impurities are converted to higher boiling sulfur-containing material, including refractive sulfur compounds, by alkylation by the olefins in the feed.

The products of the olefin modification reactor 4 be through administration 5 discharged and to the distillation column 6 where these products are fractionally distilled. From the distillation column 6 is by wire 7 stripped off a high boiling fraction comprising a hydrocarbon mixture containing alkylated sulfur-containing impurities, including refractive sulfur compounds, and leached catalyst compounds or components. From the distillation column 6 is by wire 8th withdrawn a medium-boiling fraction having a reduced sulfur content relative to the sulfur content of the original heavy naphtha feedstock and having a distillation endpoint of less than about 240 ° C. The lowest-boiling fraction is removed from the distillation column 6 by line 9 deducted.

The highest boiling third fraction from the distillation column 6 is by wire 7 passed and into the hydrodesulfurization reactor 11 initiated, and it becomes hydrogen by line 10 in the reactor 11 initiated. This third fraction will be inside the reactor 11 are contacted with a hydrodesulfurization catalyst in the presence of hydrogen under conditions effective to release at least a portion of the sulfur in the sulfur-containing impurities from the conduit 7 to convert to hydrogen sulphide. By administration 12 becomes a product from the reactor 11 deducted, which after a removal of hydrogen sulfide, a reduced sulfur content relative to that of the supply from line 7 having. The sulfur content of this product will typically be less than about 30 ppm by weight.

The middle-boiling fraction from the distillation column 6 is by wire 8th directed and into a selective hydrotreating reactor 14 initiated, and it is by line 13 Hydrogen in the reactor 14 initiated. The middle fraction is within the reactor 14 contacted with a selective hydrotreating catalyst in the presence of hydrogen under conditions effective to release at least a portion of the sulfur in the sulfur-containing impurities from the conduit 8th to convert to hydrogen sulphide. From the reactor 14 is by wire 15 withdrawn a product which, after removal of hydrogen sulphide, has a reduced sulfur content relative to both the heavy naphtha starting material for the process as well as the supply from line 8th having. The sulfur content of this product will typically be less than about 30 ppm by weight.

The lowest-boiling first fraction is from the distillation column 6 by line 9 deducted. The sulfur content of this fraction will typically be 10 ppm by weight.

The The following examples are merely illustrative of the invention and are not intended to be limiting of the invention in any way.

example 1

One Naphtha feed with the following analysis data was in a Olefin modification zone according to the present invention Contacted invention.

Table II

The Olefin modification zone consisted of two stages of a fixed bed made of solid phosphoric acid (obtained from Sud Chemie and sold under the name C84-5-01) and was at a temperature of 172 ° C in the first stage and 122 ° C in the second stage, a pressure of 500 psig and a liquid hourly space velocity operated by 1.5 LHSV.

The resulting olefin modification reaction zone product was prepared according to the method of the invention fractionally distilled into three fractions and for comparative purposes to two fractions.

The Distillations of the olefin modification zone products were in a Laboratory semi-automatic distillation unit Fischer 800 according to the method ASTM D2892 performed.

The Sample was immersed in a three liter flask with magnetic stirrer nitrogen purge heated.

The Fractionation took place in a column with a diameter of 18 mm, which was packed with a 4 mm pro pak gauze pack, so that effectively 15 theoretical Soils result.

Of the Steam was liquefied on a cooler cooled to -20 ° C, and the distillate was over a timed reflux divider at a ratio from 20: 4 in a chilled Taken recording.

Of the Temperature separation point was determined by measuring the steam temperature a resistance thermometer and an associated electronic display device.

The Unit possessed the Ability, under vacuum to distill, however, the samples were in this Fall at atmospheric pressure distilled at temperatures corrected to 760 mm.

The Distillation products were purged with nitrogen and before further testing stored under refrigeration.

The Table III below shows the relative amounts of olefin modification catalyst ("Phosphorus"), total sulfur in the comparative boiling range fractions: 100 ° C and 100 ° C + and the three boiling range fractions according to the present Invention: 100 ° C, 100 ° C to 200 ° C and 200 ° C +.

Table III Product contaminants split into two fractions versus three fractions

As can be seen from the above table, the phosphorus and the refractive sulfur is preferably concentrated in the highest boiling fraction, when the olefin modification zone effluent is divided into three fractions according to the present invention Invention is divided. The highest boiling Area has a relatively small volume, d. H. 11% by weight yield, and allows therefore, a much lower fraction of the olefin modification zone product treated by the octane reducing hydrodesulfurization process becomes. It should be noted that in the comparative bottom fraction the Yield is 50.1% by weight, which means one half of the olefin modification stream effluent is not selectively hydrotreated would be to remove refractive sulfur, resulting in an undesirable Octane loss for a half of the electricity opposite 11 % of the electricity according to the procedure the invention leads.

Example 2

In an olefin modification zone was prepared according to the present invention contacted a naphtha feedstock with the following analytical data.

Table IV

The The above feed was in an olefin modification zone, the a fixed bed of solid phosphoric acid (obtained from Sud Chemie and sold under the name C84-5-01). The Olefin modification zone was at a temperature of 193 ° C, a Pressure of 250 psig and a liquid hourly space velocity operated by 1.5.

The reaction zone product was fractionated into three fractions according to the present invention, and for comparison purposes to two fractions in a unit having the following properties: Bubble volume: ~ 1500 gallons Column height: 34'6 '' Column diameter: 12 '' with structured packing Number of theoretical plates: 33

Under With respect to the three fractions, the product was atmospheric distilled up to a head temperature of 100 ° C. The extraction conditions was 33% up to a head temperature equal to 80 ° C, 14% to to a head temperature equal to 90 ° C, 8% up to a head temperature equal to 100 ° C. The system was then completed backflow changed. The image containing the fraction IBP-100 ° C, was separated. The system was then vacuumed at 55 mmHg set and initiated a withdrawal. The extraction conditions between 5% and 8% during the fraction 100-200 ° C. The system was shut down when the head temperature reached 106 ° C at 55 mmHG reached. There were the fraction 100-200 ° C, the bubble fraction 200-FBP and the vacuum trap fraction is separated.

The Separation into two fractions for comparison was based on analog Way, resulting in a fraction IBP-100 ° C and a fraction 100 ° C + led.

The The following table shows the sulfur distribution in the according to the present Invention prepared corresponding three fractions. It should be noted that performed Fractionation was less than ideal as the fraction IBP-100 ° C was the presence of C3 + thiophenes, which are usually not present in this Faction would be present.

Table V Sulfur distribution per fraction

The comparative 100 ° C + fraction was subjected to conventional hydrotreating under the following conditions:
318 ° C
450 psig
3 LHSV

The side fraction or fraction 100-200 ° C obtained according to the present invention was subjected to a hydrotreating step at the following selective hydrotreating conditions:
307 ° C
450 psig
3 LHSV

The hydrotreating unit was a Festbetthydrotreatingpilotanlage downflow psig for processing of naphtha or distillate feeds in a single pass at hydrogen pressures of up to 2000, hydrogen flow of 5 scfh, Flüssigkeitszuführraten of 600 cm ³ / h and temperatures was configured of 800 ° F. The reactor had dimensions of about 0.96 '' inside diameter x 18 '' long and can accommodate to catalyst loading of up to 120 cm ³ and is heated by a salt bath. The catalyst bed internal temperature was monitored by a programmable single-point movable thermocouple. An LDC ConstaMetric 3200 precision metering pump pumps the feed and the hydrogen flows into the unit through a Brooks mass flow meter. The combined liquid and gas streams were passed through the downflow operated reactor and stray Man sight glass isolated. Exhaust gas pressure is controlled by means of a Rosemount thruster and a Badger control valve, where the exhaust gas flow passes through a caustic scrubber and is measured downstream at atmospheric pressure via an Alexander Wright wet strength tester. The liquid product in the separator had a level control via a Rosemount differential transmitter and a Badger control valve. The product was cooled via a tube-in-tube heat exchanger and collected via an automatic valve manifold in a cooling device, sequentially fed by computer control into one of the three product receptacles. The computer control / data acquisition was done using Analog Devices uMac 6000 and automated safety shutdowns were controlled via a Siemens Simatic TI505 PLC.

Table VI below shows the octane retention achieved with the invention while effecting deep desulfurization. It should be noted that the sulfur level in the combined overhead fraction "OVHD" and the mid-fraction "side draw" would have been significantly lower if fractionation had been performed ideally. Specifically, the combined first and second fractions ("OVHD" and "side draw") show an octane loss of 87.3 to 84.5 with a desulfurization of up to 50 ppm by weight, while the comparative method for comparable octane loss is only up to 60 ppmw desulfurized. The results would be more significant if fractionation would be more ideal. To further achieve the product sulfur in the combined comparative fraction, the hydrodesulfurization conditions would have to be much stronger and would be:
332 ° C
450 psig
1.5 LHSV

The stronger Conditions would result in a further octane loss of 33.1% of the stream.

Table VI Retention of Octane in Two-Fraction Splitters vs. Three-Fraction Splitters

Claims (19)

A process for producing a reduced sulfur product from a feedstock, wherein the feedstock contains sulfur-containing organic contaminants and comprises a normally liquid mixture of hydrocarbons including olefins, the process comprising: (a) contacting the feedstock with an olefin modification catalyst in at least one olefin modification reaction zone under conditions effective to produce a product having a bromine number less than that of the feedstock, and wherein the product contains refractive sulfur compounds; (b) fractionating the product from the olefin modification reaction zone to produce: (i) a first fraction comprising sulfur-containing organic contaminants having a distillation endpoint less than about 140 ° C; (ii) a second fraction boiling higher than the first fraction comprising sulfur-containing organic contaminants and having a distillation endpoint less than about 240 ° C; and (iii) a third fraction boiling higher than the second fraction and comprising sulfur-containing organic impurities and refractive sulfur compounds; (c) contacting the second fraction with a selective hydrotreating catalyst in the presence of hydrogen in a selective hydrotreating reaction zone under conditions effective to convert at least a portion of the sulfur-containing impurities in the second fraction to hydrogen sulfide; and (d) contacting the third fraction with a hydrodesulfurization catalyst in the presence of hydrogen in a hydrodesulfurization reaction zone under conditions effective to convert at least a portion of the sulfur in the sulfur-containing impurities of the third fraction to hydrogen sulfide. The method of claim 1, wherein the feedstock Contains paraffins and wherein the conditions in the olefin modification reaction zone are effective to produce a product having a bromine number which is lower than that of the feedstock, and being less than 10% of the paraffins cracked in the feed. The method of claim 1, additionally comprising Removing hydrogen sulfide from the effluent of the selective Hydrotreating reaction zone comprises a desulfurized product to give, by weight, less than about 50 ppm contains sulfur. The method of claim 3, wherein the octane of the desulphurised product at least 95% of that of the feedstock to the olefin modification reaction zone. The method of claim 1, wherein the feedstock of about 0.05 wt% to about 0.7 Wt .-% of sulfur in the form of organic sulfur compounds contains. The method of claim 1, additionally comprising Removing hydrogen sulfide from the effluent from the hydrodesulfurization reaction zone to give a desulfurized product by weight less than about Contains 50 ppm of sulfur. The method of claim 6, wherein the octane of the desulphurised product at least 90% of that of the feedstock to the olefin modification reaction zone. The method of claim 1, wherein the feedstock Containing impurities containing basic nitrogen and that Additional procedure removal of impurities containing basic nitrogen, from the feedstock before it reacts with the olefin modification catalyst is brought into contact. The method of claim 8, wherein the feedstock Hydrocarbons from a catalytic cracking process comprises. The method of claim 1, wherein the feedstock essentially free of impurities, the basic nitrogen included is. The method of claim 1, wherein the feed a mixture of hydrocarbons that includes gasoline boils. The method of claim 1, wherein the feedstock treated naphtha, which is prepared by removing of impurities containing basic nitrogen from one Naphtha made by a catalytic cracking process becomes. The method of claim 1, wherein the third Fraction from 2 to 10% by volume of the product from the olefin modification reaction zone enough. The method of claim 1, wherein the feedstock has an initial boiling point, the is below about 79 ° C and has a distillation endpoint no greater than about 345 ° C. The process of claim 1, wherein the olefin modification catalyst selected from the group That is, from all solid acid catalysts exists, and in which (i) the first fraction, which contains sulfur organic contaminants comprises a distillation end point which is less than about 120 ° C; (Ii) the second fraction, which higher boils as the first fraction, which contains sulfurous organic Contains impurities having a distillation endpoint, the less than about 200 ° C is; and (iii) the third fraction, which boils higher than the second fraction, Sulfur-containing organic impurities and refractive sulfur compounds includes. The method of claim 15, additionally comprising Removing hydrogen sulfide from the effluent of the selective Hydrotreating reaction zone comprises a desulfurized product which has an octane which is at least 98% of that of the feedstock to the olefin modification reaction zone is. The method of claim 15, additionally comprising Removing hydrogen sulfide from the effluent from the hydrodesulfurization reaction zone to give a desulfurized product containing an octane which is at least 97% of that of the feedstock the olefin modification reaction zone. The method of claim 15, wherein the feedstock Hydrocarbons from a catalytic cracking process comprises. The method of claim 15, wherein the feedstock comprises a treated naphtha prepared by removal of impurities containing basic nitrogen from one Naphtha made by a catalytic cracking process becomes.