KR20040002776A - A process for reducing sulfur and olefin contents in gasoline - Google Patents

Abstract

PURPOSE: A process for producing gasoline products containing less than 200 ppm of sulfur and less than 20 wt.% of olefin by reducing sulfur and olefin contents of gasoline as minimizing loss of octane value in gasoline is provided. CONSTITUTION: The process comprises a step (a) of contacting gasoline supply raw materials and hydrogen with hydrotreating catalyst under the reaction conditions including 200 to 600 Nm¬3/m¬3 of a hydrogen/gasoline ratio, 1.0 to 4.0 MPa of hydrogen partial pressure, 200 to 380 deg.C of temperature, and 3.0 to 5.0 h¬-1 of space velocity of liquid per hour; and a step (b) of forming an effluent by contacting the hydrotreated gasoline and hydrogen with an octane value recovery catalyst under the reaction conditions including 200 to 1000 Nm¬3/m¬3 of a hydrogen/gasoline ratio, 1.0 to 4.0 MPa of hydrogen partial pressure, 300 to 460 deg.C of temperature, and 0.5 to 4.0 h¬-1 of space velocity of liquid per hour, and obtaining hydrogenation treated gasoline fraction by separating the effluent.

Description

A process for reducing sulfur and olefin contents in gasoline}

The present invention relates to a process for purifying hydrocarbon oils in the presence of hydrogen. More specifically, the present invention relates to a method for reducing the sulfur and olefin content in gasoline.

As interest in environmental protection increases worldwide, harmful components in the exhaust of automobiles will be tightly controlled. In response to such control, the quality of the fuel is required to be even higher. Thus, many countries impose strict limits on the quality targets of automotive gasoline, such as, for example, oxygen content, vapor pressure, benzene content, total aromatic content, boiling point, olefin content, sulfur content and the like. Thus, as required by CAAA (USA), in the nine most severely polluted states, by 2004, the sulfur content of the reformed gasoline (RFG) should be less than 30 ppm and its olefin content of 8.5 Should be less than% The European Parliament also enacted legislation requiring that by 2005, the sulfur and olefin content of gasoline should be less than 30-50 ppm and less than 18%, respectively. Therefore, an important task in the refinery industry is to develop methods for further reducing the sulfur and olefin content of gasoline.

The main reason for the high sulfur and olefin content of automotive gasoline is the high proportion of FCCC gasoline (fluidized catalytic cracking gasoline) in the gasoline pool. For example, in China, FCC gasoline is a major blending component that accounts for over 80% of gasoline blending pools. FCC gasoline contains high concentrations of sulfur and olefins, especially when the raw material of the FCC is heavy oil.

In fact, the use of conventional hydrogenation processes can also significantly reduce the content of both sulfur and olefins in FCC gasoline. However, the hydrogenation process saturates the olefin, which is a high octane number component. As a result, this process results in severe octane number loss, especially when using gasoline feedstocks having relatively high olefin content and relatively low aromatic content. In view of this, there is a need to develop an FCC gasoline treatment process that can reduce sulfur and olefin content while minimizing octane number losses.

USP 5,411,658 discloses a gasoline hydrorefining process comprising hydrocracking FCC gasoline using a conventional hydrorefining catalyst and restoring the octane number of the hydrorefined gasoline using a β-zeolite catalyst. . This method is designed to process feedstocks with a high final boiling point. Nevertheless, this method saturates a large amount of aromatics because it uses high hydrorefining temperatures. As a result, the octane number of the final product is significantly reduced and very difficult to recover.

USP 5,399,258 discloses a gasoline upgrading method. This method involves two steps. In the first step, the feedstock undergoes a hydrogenation reaction that removes sulfur and nitrogen and saturates the olefins. The product of the first stage is immediately fed into the second stage, where the octane undergoes a recovery reaction. The first stage proceeds at a high temperature similar to the temperature of the second stage. Nevertheless, due to the high reaction temperature of the first step, a large amount of mercaptan sulfur remains in the final product of the process.

In the case of using a gasoline feedstock having a relatively low species point, a relatively high olefin content and a relatively low aromatic content, the aforementioned methods, when applied to reduce the sulfur and olefin content of the gasoline feedstock, Severe octane can cause losses.

Therefore, there is still a need for a method of hydrotreating gasoline, especially gasoline having a relatively low species point, a relatively high olefin content and a relatively low aromatic content, to greatly reduce the content of sulfur and olefins while minimizing octane number loss.

It is an object of the present invention to provide a method for producing a gasoline product having a sulfur content of less than 200 ppm and an olefin content of less than 20% by reducing the sulfur and olefin content of the gasoline while minimizing the loss of octane number of the gasoline. .

1 is a process diagram schematically illustrating the method of the present invention.

2 is a process diagram schematically illustrating a preferred embodiment of the method of the present invention.

The method of the present invention comprises the following steps:

(a) Hydrogen / gasoline ratio of 200 to 600 Nm ³ / m ³ , hydrogen partial pressure of 1.0 to 4.0 MPa, temperature of 200 to 380 ° C. and liquid hourly space velocity of 3.0 to 5.0 h ⁻¹ Contacting the gasoline feedstock and hydrogen with a hydrorefining catalyst under reaction conditions comprising; And

(b) under reaction conditions including a hydrogen / gasoline ratio of 200-1000 Nm ³ / m ³ , a hydrogen partial pressure of 1.0-4.0 MPa, a temperature of 300-460 ° C. and a liquid hourly space velocity of 0.5-4.0 h ⁻¹ , Contacting the hydrogenated gasoline and hydrogen with an octane number recovery catalyst to form an effluent, and separating the effluent to obtain a hydrogenated gasoline fraction.

Basically, the invention can be carried out as follows:

Gasoline feedstock under reaction conditions including hydrogen / gasoline ratio of 200-600 Nm ³ / m ³ , hydrogen partial pressure of 1.0-4.0 MPa, temperature of 200-380 ° C. and liquid hourly space velocity of 3.0-5.0 h ⁻¹ And hydrogen are contacted with a hydrorefining catalyst. The hydrogenation tablet under reaction conditions including a hydrogen / gasoline ratio of 200-1000 Nm ³ / m ³ , a hydrogen partial pressure of 1.0-4.0 MPa, a temperature of 300-460 ° C. and a liquid hourly space velocity of 0.5-4.0 h ⁻¹ Gasoline and hydrogen are contacted with an octane number recovery catalyst. The effluent obtained in the octane number recovery reaction is separated to obtain a hydrotreated gasoline fraction.

The gasoline feedstock is FCC gasoline, deep catalytic cracking gasoline, DC- gasoline, straight-run gasoline, coker gasoline, pyrolysis gasoline, pyrolysis gasoline and thermal cracking gasoline Mixtures. The gasoline feedstock may be the total fraction of the gasoline mentioned above. Alternatively, the gasoline feedstock may be part of the total fraction of gasoline mentioned above, in which case the gasoline feedstock is a heavy fraction cut at a temperature of 70-100 ° C. The gasoline feedstock contains 1 to 60% by volume of olefins, preferably 20 to 55% by volume.

The hydrorefining catalyst is suitably a conventional desulfurization catalyst comprising one or more non-noble metals selected from group VIB and / or group VIII, supported on amorphous alumina or amorphous aluminum silicate.

The octane number recovery catalyst comprises at least one non-noble metal or precious metal selected from group VIB and / or group VIII supported on zeolite. Preferred octane number recovery catalysts comprise 0.5-10% by weight and 10-75% by weight of zeolite of at least one metal selected from Group VIII, the remainder being alumina. Most preferred octane number recovery catalysts comprise 1-5 wt% Ni and W, 30-40 wt% ZMS-5 zeolite, with the remainder being alumina.

The hydrorefining and octane number recovery reactions are typically carried out in fixed bed reactors.

The process of the present invention makes it possible to reduce the olefin content by at least 40% while minimizing octane number loss while maximizing sulfur removal.

The process of the invention is preferably carried out as follows:

1. Cut the gasoline feedstock into light and heavy oil at a temperature of 70-100 ° C.

2. The light fraction is extracted with alkali to cause sweetening, ie to remove mercaptan.

3. The heavy fraction is contacted with hydrogenation catalyst with hydrogen. The effluent obtained from the hydrorefining reaction is contacted with an octane number recovery catalyst without separation. The effluent obtained from the octane number recovery reaction is separated to obtain a light hydrocarbon and hydrogenated gasoline fraction, where hydrogen-rich gas is recycled.

4. Mix the sweetened light fraction and the gasoline fraction hydrotreated in step 3 into a gasoline pool.

Gasoline feedstocks used in preferred embodiments of the present invention are FCC gasoline, DCC gasoline, direct gasoline, coker gasoline, cracked gasoline, pyrolysis gasoline or mixtures thereof. Gasoline feedstocks typically have a type point of 220 ° C. or less.

The alkali used in step 2 is a hydroxide of an alkali metal or alkaline earth metal, such as sodium hydroxide. The alkali is usually used as an aqueous solution.

In step 3, the hydrorefining agent typically has a hydrogen / gasoline ratio of 200 to 600 Nm ³ / m ³ , a hydrogen partial pressure of 1.0 to 4.0 MPa, a temperature of 200 to 380 ° C. and a liquid hourly space velocity of 3.0 to 5.0 h ⁻¹ It proceeds under reaction conditions including. The catalyst used in the hydrorefining process comprises at least one non-noble metal selected from group VIB and / or group VIII, supported on amorphous alumina or amorphous aluminum silicate. The octane number recovery process comprises a hydrogen / gasoline ratio of 200 to 1000 Nm ³ / m ³ , a hydrogen partial pressure of 1.0 to 4.0 MPa, a temperature of 300 to 460 ° C. and a liquid hourly space velocity of 0.5 to 4.0 h ⁻¹ Under the conditions.

The hydrotreated gasoline fraction, obtained from the hydrorefining of the heavy fraction and the octane number recovery process, does not contain mercaptan sulfur and does not require an additional treatment process to remove the mercaptan. As such, it can be mixed with the sweetened light fractions to provide a final gasoline product having a mercaptan content of less than 10 ppm. Even in the case of gasoline having high (eg up to 55 vol%, even up to 60 vol%) olefin content, low (eg less than 20 vol%) aromatic content and low species point, the present invention is well known. Applied, final gasoline with a sulfur content of less than 200 ppm and an olefin content of less than 20% by volume, with no loss of antiknock index (= (RON + MON) / 2) or even slightly elevated antiknock index Provide the product.

The present invention will be described in more detail with reference to the accompanying drawings.

Referring to FIG. 1, the gasoline feedstock is introduced into the pump 7 through the conduit 4, and the pressurized feedstock passed through the conduit 8 is mixed with the hydrogen enriched gas passing through the conduit 22. After mixing with the hydrogen enrichment gas, the gasoline feedstock is passed through the conduit 9 into the heat exchanger 10 and then through the conduit 11 into the hydrorefining reactor 12, which is a hydrorefining reactor. Typically fixed bed reactors are used. In the hydroreactor reactor 12, the gasoline feedstock and hydrogen are in contact with the hydrorefining catalyst contained therein. The effluent from the hydrorefining reactor 12 is fed to the octane number recovery reactor 14 via conduit 13. In the octane number recovery reactor 14, the hydrogenated gasoline feedstock and hydrogen are in contact with the octane number recovery catalyst contained therein. The effluent from the octane number recovery reactor 14 enters the heat exchanger 10 through the conduit 15 and then enters a downstream unit (not shown) through the conduit 16 where it is separated and hydrotreated gasoline. Produces oil.

2 is a process diagram of a preferred embodiment of the present invention. As shown in FIG. 2, the gasoline feedstock is fed to the fractionator 2 via a conduit 1, where it is cut into light and heavy fractions. The light fraction is introduced into the alkali scrubbing unit 5 through the conduit 3, and after alkali scrubbing, exits the alkaline scrubbing unit 5 as a sweet hard oil to remove the conduit 6 Flows through. On the other hand, the heavy oil is introduced into the pump 7 through the conduit 4, the pressurized heavy oil passing through the conduit 8 is mixed with the hydrogen enrichment gas passed through the conduit 22. The mixture enters the heat exchanger 10 through conduit 9 and then enters the fixed-phase hydroreactor 12 through conduit 11, where it is in contact with the hydrorefining catalyst. The effluent from the fixed bed hydrorefining reactor 12 enters the octane number recovery reactor 14 through a conduit 13, where it contacts the octane number recovery catalyst. Effluent from the octane number recovery reactor 14 passes through conduit 15, heat exchanger 10 and conduit 16 to high pressure separator 17 where it is separated into hydrogen enriched gas and liquid product. Hydrogen enriched gas from the top of separator 17 enters gas compressor 19 through conduit 18. Pressurized hydrogen enriched gas that has passed through conduit 20 can be selectively mixed with fresh hydrogen that has passed through conduit 21, and after passing through conduit 22, with heavy oil passing through conduit 8; Are mixed. On the other hand, the liquid product from the bottom of separator 17 enters a stabilizer 24 through conduit 23, where it is separated into light hydrocarbons and hydrotreated gasoline fractions, each of which is a conduit 25. And out of the stabilizer 24 through the conduit 26. Eventually, the sweetened light fraction passed through conduit 6 and the hydrotreated gasoline fraction passed through conduit 26 are mixed and exited conduit 27 as the final gasoline product.

The following examples are intended to illustrate the invention. In the examples below, the hydrorefining catalyst and the octane number recovery catalyst used are available from "Catalyst Plant of Changling Refinery", "China Petroleum & Chemical Corporation (Yueyang City, Hunan Province, PRC)" CH-18 "and" RIDOS-1 ". The properties of these catalysts are summarized in Table 1.

catalyst CH-18 RIDOS-1 Composition, weight% WO ₃ ≥ 19.0 - NiO ≥ 2.0 - CoO ≥ 0.04 - SiO ₂ - 61 ± 4 Na ₂ O - ≤ 0.3 Fe ₂ O ₃ - ≤ 0.3 Physical properties Surface area, m ² / g ≥ 130 <280 Pore volume, ml / g ≥ 0.27 ≥ 0.25 Strength, N / mm ≥ 16 ≥ 12

Comparative Example

The feedstock FCC gasoline A was cut at 80 ° C. to give 67.5% by weight of heavy oil (the rest was light oil). The properties of the feedstock are summarized in Table 2. The heavy fraction and hydrogen were contacted with the hydrorefining catalyst CH-18, but no octane number recovery process was performed. The hydrorefined heavy fraction was mixed with the light fraction through the sweetening process to obtain the final gasoline product. Hydrorefining conditions and product characteristics are summarized in Table 3. Table 3 shows that the final gasoline product has a sulfur content of 8 ppm. However, the product lost an antiknock index (= (RON + MON) / 2) by 9.9. In addition, the characteristics of heavy and hydrogenated gasoline fractions are summarized in Table 4.

<Example 1>

The comparative example was repeated except that heavy fractions were additionally subjected to the octane number recovery process in the presence of a RIDOS-1 catalyst. The hydrotreated gasoline fraction, obtained from the hydrorefining of the heavy fraction and the octane number recovery process, was mixed with the light fraction, which had undergone the sweetening process, to obtain a final gasoline product. The reaction conditions and product characteristics are summarized in Table 3. Table 3 shows that the final gasoline product has a sulfur content of 9 ppm and an olefin content of 18.2% by volume. In addition, the product has an antiknock index increased by 0.2. In addition, the characteristics of heavy and hydrogenated gasoline fractions are summarized in Table 4.

<Example 2>

FCC gasoline B, a feedstock, was cut at 88 ° C. to yield 69.8% by weight of heavy oil based on the feedstock (the rest was light). The characteristics of the feedstock are summarized in Table 2. The heavy fraction was hydropurified in the presence of a CH-18 catalyst and then subjected to an octane number recovery process in the presence of a RIDOS-1 catalyst. The hydrotreated gasoline fraction, obtained from the hydrorefining of the heavy fraction and the octane number recovery process, was mixed with the light fraction, which had undergone the sweetening process, to obtain a final gasoline product. The reaction conditions and product characteristics are summarized in Table 3. Table 3 shows that the product has a sulfur content of 161 ppm and an olefin content of 16.9% by volume. In addition, the product has an antiknock index increased by 1.2. In addition, the characteristics of heavy and hydrogenated gasoline fractions are summarized in Table 4.

<Example 3>

The feedstock FCC gasoline C was cut at 95 ° C. to give 60.1% by weight of heavy oil based on the feedstock (the rest was light oil). The characteristics of the feedstock are summarized in Table 2. The heavy fraction was hydropurified in the presence of a CH-18 catalyst and then subjected to an octane number recovery process in the presence of a RIDOS-1 catalyst. The hydrotreated gasoline fraction, obtained from the hydrorefining of the heavy fraction and the octane number recovery process, was mixed with the light fraction, which had undergone the sweetening process, to obtain a final gasoline product. The reaction conditions and product characteristics are summarized in Table 3. Table 3 shows that the final gasoline product has a sulfur content of 100 ppm and an olefin content of 19.8% by volume. In addition, the product has an anti-knock index reduced by only 0.6. In addition, the characteristics of heavy and hydrogenated gasoline fractions are summarized in Table 4.

Feedstock characteristics Feedstock A Feedstock B Feedstock C Density (20 ° C), g / cm ³ 0.7112 0.7083 0.7382 Sulfur content, ppm 85 1400 1300 Olefin Content, Volume% 49.3 38.6 54.3 Distillation phase, ℃ Superstore 30 34 45 10% 48 44 50 50% 87 84 100 Kind store 181 196 211 Antiknock Index 85.2 84.9 87.3

Reaction Condition and Product Characteristics Comparative example Example 1 Example 2 Example 3 Partial pressure of hydrogen, MPa 3.2 3.2 3.2 3.2 Temperature, ℃ Hydrogen Purification 220 280 280 290 Octane number recovery - 370 370 380 Liquid hourly space velocity, hr ^-1 Hydrogen Purification 4.0 4.0 4.0 4.0 Octane number recovery - 0.8 0.8 0.8 Hydrogen / gasoline ratio, Nm ³ / m ³ 500 500 500 500 Characteristics of the product Density (° C), g / cm ³ 0.7077 0.6997 0.7077 0.7300 Sulfur content, ppm 8 9 161 100 Olefin Content, Volume% 19.3 18.2 16.9 19.8 Antiknock Index 75.3 85.4 86.1 86.7

Characteristics of the product Sulfur, ppm Olefin, Volume% Antiknock Index Comparative example Heavy oil 106 47.2 83.0 Hydrotreated Gasoline Oil 10 19.3 75.3 Example 1 Heavy oil 106 47.2 83.0 Hydrotreated Gasoline Oil 5 0 79.6 Example 2 Heavy oil 2100 34.8 82.6 Hydrotreated Gasoline Oil 28 0 82.6 Example 3 Heavy oil 1502 46.9 85.4 Hydrotreated Gasoline Oil 35 0 81.2

Of course, the foregoing description and examples are merely exemplary and should not be taken as a limitation on the scope of the invention, which is defined solely by the appended claims and their equivalents. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the scope of the present invention.

The method of the present invention makes it possible to reduce the olefin content of gasoline by at least 40% while minimizing the octane number loss of gasoline, while maximizing sulfur removal of gasoline.

By using the process of the present invention, sulfur content of less than 200 ppm and olefins of less than 20% by volume, with no loss of antiknock index (= (RON + MON) / 2) or even slightly raising the antiknock index It is possible to provide a final gasoline product having a content.

The process of the present invention is for gasoline having high olefin content, low (eg less than 20% by volume) aromatic content and low species point (high up to 55% by volume, even up to 60% by volume). Also, it can be usefully applied.

Claims (10)

(a) under reaction conditions including a hydrogen / gasoline ratio of 200-600 Nm ³ / m ³ , a hydrogen partial pressure of 1.0-4.0 MPa, a temperature of 200-380 ° C. and a liquid hourly space velocity of 3.0-5.0 h ⁻¹ , Contacting the gasoline feedstock and hydrogen with a hydrorefining catalyst; And (b) under reaction conditions including a hydrogen / gasoline ratio of 200-1000 Nm ³ / m ³ , a hydrogen partial pressure of 1.0-4.0 MPa, a temperature of 300-460 ° C. and a liquid hourly space velocity of 0.5-4.0 h ⁻¹ , Contacting the hydrogenated gasoline and hydrogen with an octane number recovery catalyst to form an effluent, and separating the effluent to obtain a hydrogenated gasoline fraction. A method for reducing the sulfur and olefin content of gasoline. 2. The method of claim 1, wherein the gasoline feedstock is a fraction of the total fraction or a fraction of the total fraction of the FCC gasoline, DCC gasoline, direct current gasoline, coker gasoline, cracked gasoline, pyrolysis gasoline or mixtures thereof. 3. The method of claim 2, wherein the gasoline feedstock is a heavy fraction cut at a temperature of 70-100 ° C of FCC gasoline, DCC gasoline, direct gasoline, coker gasoline, cracked gasoline, pyrolysis gasoline or mixtures thereof. . 4. The hard oil cut off of the FCC gas, DCC gasoline, direct gasoline, coker gasoline, cracked gasoline, pyrolysis gasoline or a mixture thereof at a temperature of 70-100 ° C. is sweetened and the sweet light oil is sweetened. Is mixed with the hydrotreated gasoline fraction to obtain a final gasoline product. 2. The process of claim 1 wherein the gasoline feedstock contains 1-60% by volume of olefins. 6. The process of claim 5 wherein the gasoline feedstock contains 20-55% by volume of olefins. The method of claim 1 wherein the hydrorefining catalyst comprises at least one non-noble metal selected from Group VIB and / or Group VIII, supported on amorphous alumina or amorphous aluminum silicate. The method of claim 1 wherein the octane number recovery catalyst comprises at least one non-noble or precious metal selected from Group VIB and / or Group VIII supported on zeolite. 9. The octane number recovery catalyst according to claim 1 or 8, wherein the octane number recovery catalyst comprises from 0.5 to 10% by weight of zeolite, and from 10 to 75% by weight of zeolite, wherein the remainder is alumina. How to. 10. The method of claim 9, wherein the octane number recovery catalyst comprises 1-5 wt.% Ni and W, 30-40 wt.% ZMS-5 zeolite, the remainder being alumina.