JP2007513247A - Quality improvement method of catalytic cracking raw material by sulfuric acid solution treatment - Google Patents

Abstract

The present invention relates to the use of an acid treatment process for removing nitrogen-containing heterocyclic compounds from a feed stream and then subjecting the feed stream having a reduced amount of nitrogen-containing compounds to catalytic cracking.
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Description

  The present invention relates to an improved catalytic cracking process for hydrocarbon streams. More particularly, the present invention relates to the use of an acid treatment method to remove a nitrogen-containing heterocyclic compound from a feed stream and then subject the feed stream having a reduced amount of nitrogen-containing compound to catalytic cracking.

  Today, nitrogen-containing heterocyclic compounds, especially basic nitrogen-containing heterocyclic compounds, act as competitive inhibitors for the acidic decomposition point of the cracking catalyst, so that the feed stream used in catalytic cracking operations There is a need to reduce the heterocyclic nitrogen content. These nitrogen-containing compounds were originally present in crude oil and are usually concentrated in high boiling fractions such as straight run gas oil (VGO). These nitrogen-containing heterocyclic compounds significantly reduce the catalytic cracking conversion in the catalytic cracking operation even at low levels on the order of hundreds of parts per million ("wppm"). In the catalytic cracking operation, it is generally known that the conversion decreases by 1% for every 100 wppm nitrogen in the raw material fed to the process. Therefore, many methods have been proposed so far for reducing the nitrogen content in the feed stream used in catalytic cracking operations.

  For example, U.S. Patent No. 6,057,059 (Fraytet) teaches the use of concentrated sulfuric acid, i.e., at least 95% by weight sulfuric acid, to treat a straight run jet fuel boiling range stream. This method requires that the sulfuric acid-containing stream be dispersed in jet fuel in the form of droplets smaller than about 300 microns. The Freytet process discloses that 90% or more of nitrogen can be removed from jet fuel boiling range streams.

US Statutory Invention Registration No. H1368 Specification US Pat. No. 3,758,404

  Therefore, there is still a need in this field for a more effective nitrogen removal method for catalytic cracking boiling range feed streams, as an improvement in total catalytic cracking operations is expected.

The present invention provides an improved catalytic cracking process comprising removing nitrogen from a nitrogen-containing catalytic cracking boiling range feed stream. This method
a) providing a sulfuric acid solution containing sulfuric acid in an amount greater than about 75% by weight;
b) In the first reaction stage, the nitrogen-containing catalytic cracking boiling range feed stream, under effective conditions, with an acid solution volumetric treatment rate of greater than about 0.5% by volume, based on the catalytic cracking boiling range feed stream, Contacting with the sulfuric acid solution to produce a first reaction stage effluent comprising at least a catalytic cracking boiling range effluent and a spent sulfuric acid solution, wherein about the nitrogen compounds contained in the catalytic cracking boiling range feed stream A step in which more than 60% by weight is removed; and c) at least a portion of the first reaction stage effluent to a second reaction stage in which the first reaction stage effluent contacts a cracking catalyst under effective cracking conditions. Including a guiding step.

In one embodiment of the invention, the sulfuric acid solution is a spent sulfuric acid solution obtained from an alkylation process equipment, and the spent sulfuric acid solution is
The olefinic hydrocarbon feed stream containing a) C ₄ olefins in combination with isobutane to produce a hydrocarbonaceous mixture process; a and b) said hydrocarbonaceous mixture, having an acid concentration of alkylate and at least about 75 wt% Produced by contacting the sulfuric acid solution with sulfuric acid under conditions effective to produce at least.

  Note that “cat cracker” and “catalytic cracking” are used interchangeably herein. These terms are intended to encompass any catalytic cracking operation such as, for example, fluid catalytic cracking, steam cracking, hydrocracking.

  The present invention is an improved catalytic cracking process comprising removing nitrogen compounds from a nitrogen-containing catalytic cracking boiling range feed stream. The method includes, in a first reaction stage, contacting the catalytic cracking boiling range feed stream with a sulfuric acid solution to reduce the nitrogen content of the catalytic cracking boiling range feed stream by at least about 60% by weight. Contacting the catalytic cracking boiling range feed stream with a sulfuric acid solution produces a first reaction stage effluent comprising at least a catalytic cracking boiling range effluent and a spent sulfuric acid solution. At least a portion of the first reaction stage effluent is then directed to a second reaction stage where the first reaction stage effluent contacts the cracking catalyst under effective cracking conditions.

  Examples of the raw material stream suitable for the treatment by the nitrogen removal method include various conventionally known catalytic cracking raw material streams. A typical such feed stream is a heavy hydrocarbon feedstock having a boiling point of about 430 ° F to about 1050 ° F (220-565 ° C), such as light oil, and a boiling point of 1050 ° F (565 ° C). Heavy hydrocarbon oils containing excess substances; heavy and extracted petroleum-based crude oils; petroleum atmospheric residue; petroleum vacuum residue; pitch, asphalt, bitumen and other heavy hydrocarbon residues; tar sand oil; shale oil; Liquid products from the coal liquefaction process; and mixtures thereof. The cat cracker feed stream may also contain recycled hydrocarbons such as light or heavy cycle oils. A preferred feedstock for use in the disclosed method is vacuum gas oil having a boiling point greater than about 650 ° F. (343 ° C.).

  Catalytic cracking boiling range feed streams suitable for treatment by the present process also contain nitrogen-containing heterocyclic compounds. The nitrogen content of such streams is usually about 10,000-100 wppm, preferably about 5000-200 wppm, more preferably about 3000-500 wppm. Nitrogen compounds exist as both basic and non-basic nitrogen species. Examples of basic nitrogen species include, but are not limited to, quinolines and substituted quinolines, benzoquinolines such as acridine, anilines, N-alkylindoles, alkylarylamines and substituted derivatives thereof. Is not to be done. Examples of non-basic nitrogen species include, but are not limited to, indoles, carbazoles, benzocarbazoles, amides such as quinolones, and substituted derivatives thereof.

  Catalytic cracking boiling range feed streams suitable for treatment by the present process also contain metals such as nickel, vanadium, copper, iron and sodium. The total metal concentration in the cat cracker boiling range feed stream is usually about 10 to about 1000 wppm, preferably about 50 to 500 wppm, more preferably about 100 wppm to about 300 wppm.

  In the practice of the present invention, the catalytic cracking boiling range feed stream defined above is in intimate contact with the sulfuric acid solution in the first reaction stage to produce at least 60 wt% of both basic and non-basic nitrogen species. Removing, resulting in a first reaction stage effluent comprising at least a catalytic cracking boiling range effluent and a spent sulfuric acid solution. Suitable sulfuric acid solutions for use herein are at least about 75% by weight, preferably greater than about 80% by weight, more preferably greater than about 85% by weight, most preferably from about 85% to about 93% by weight. It contains sulfuric acid. The sulfuric acid solution may be obtained by any known method.

The sulfuric acid solution is a used sulfuric acid solution obtained from an alkylation process apparatus, and the sulfuric acid concentration is preferably within the above range. Representative alkylation process, in combination with isobutane olefinic hydrocarbon feed stream containing C ₄ olefins include those that produce a hydrocarbon mixture. This hydrocarbon mixture is then contacted with sulfuric acid. The sulfuric acid contacted with the hydrocarbon mixture is typically reagent grade sulfuric acid having an acid concentration of at least about 95% by weight. The sulfuric acid concentration is preferably higher than about 97% by weight. The hydrocarbon mixture is contacted with sulfuric acid at least under conditions effective to produce an alkylate and sulfuric acid solution. The sulfuric acid solution so produced contains at least about 75% by weight sulfuric acid and about 0.5 to about 5% water, with the remainder being acid-soluble hydrocarbons. Select effective conditions such that the sulfuric acid solution so produced contains about 82-93% by weight sulfuric acid and about 1 to about 4% by weight water, with the remainder being acid-soluble hydrocarbons. Is more preferable. However, effective conditions are such that the sulfuric acid solution so produced contains about 85 to 93% by weight sulfuric acid and about 1.5 to about 4% by weight water with the remainder being acid-soluble hydrocarbons. Most preferably, is selected.

  At least about 75%, preferably more than about 75%, more preferably more than about 85%, most preferably about 85% to about 93% by weight of sulfuric acid at the above concentration, i.e. based on sulfuric acid solution. Note that it is within the scope of the present invention to dilute the sulfuric acid solution obtained from the alkylation unit or others with a suitable diluent, preferably water, to provide a sulfuric acid solution containing any sulfuric acid. I want to be. To measure the sulfuric acid concentration after adding the diluent to the sulfuric acid solution, the sulfuric acid content and water content are measured by standard analytical methods. The equivalent acid strength can then be calculated by the following formula: equivalent sulfuric acid weight% = sulfuric acid weight% / (sulfuric acid weight% + water weight%). For example, if the spent acid from alkylation contains 87% by weight sulfuric acid, 6% by weight water and 7% by weight acid soluble hydrocarbon, the equivalent sulfuric acid concentration of this acid is 94% by weight. % (87 / (87 + 6)). Therefore, by adding water to the spent acid from this alkylation, the equivalent strength can be adjusted to the concentration range described above.

  The catalytic cracking boiling range feed stream is contacted with the sulfuric acid solution under effective conditions and at an acid volume treat rate greater than about 0.50% by volume based on the catalytic cracking boiling range feed stream. The acid volume treatment rate is preferably about 0.5 to about 20% by volume, more preferably about 0.5 to about 10% by volume, and most preferably about 0.5 to about 5% by volume. Contacting can be done by any suitable method including both dispersion and non-dispersion methods. Examples of suitable dispersion methods include, but are not limited to, mixing valves, mixing tanks or containers, propeller mixers, in-line static mixers and orifice plates. Examples of non-dispersing methods include, but are not limited to, a packed bed of inert particles and a fiber film contactor such as that described by US Pat. Is not to be done. U.S. Patent No. 6,057,089, which is incorporated herein by reference, includes contacting along a bundle of metal fibers rather than a packed bed of inert particles. In one embodiment, the contact method is non-dispersive, and in another embodiment, the contact method is classified as a distributed method.

  As mentioned above, the cat cracker boiling range feed stream is contacted with sulfuric acid under effective conditions. Effective conditions include removal of greater than about 60%, preferably greater than about 75%, and more preferably greater than about 90% by weight of the nitrogen in the catalytic cracking boiling range feed stream by the present process. Should be considered a condition. Effective conditions also indicate that the yield loss that occurs during the sulfuric acid solution treatment is from about 0.5 to about 30 wt%, preferably from about 0.5 to about 20 wt%, more preferably from about 0.5 to It should be considered as a condition that minimizes to about 10% by weight.

  Contacting the catalytic cracking boiling range feed stream and sulfuric acid in the first reaction stage produces a first reaction stage effluent comprising at least the catalytic cracking boiling range effluent and the spent sulfuric acid solution. At least a portion, preferably substantially all, of the first reaction stage effluent is introduced therefrom into a second reaction stage that contacts the cracking catalyst under effective cracking conditions. However, it is preferred to separate the first reaction stage effluent into at least a catalytic cracking boiling range effluent and a spent sulfuric acid solution containing the now removed nitrogen compound. The spent sulfuric acid solution and the catalytic cracking boiling range effluent can be separated by any means known to be effective in separating acids from hydrocarbon streams. Examples of suitable separation methods include, but are not limited to, gravity sedimentation, sedimentation by electric fields, centrifugation, sedimentation by microwaves and accelerated sedimentation by cohesive surfaces. However, the catalytic cracking boiling range effluent and the spent sulfuric acid solution are preferably separated in layers in a separation device such as a sedimentation tank or drum, coalescer, electrostatic precipitator or other similar device. It is also possible to use the fiber film contactor described above to separate the spent sulfuric acid solution produced by this process from the catalytic cracking boiling range effluent. Thereafter, at least a portion, preferably substantially all, of the catalytic cracking boiling range effluent can be introduced into a suitable cracking operation.

  As mentioned above, the effective conditions for contacting the catalytic cracking boiling range feed stream and the sulfuric acid solution should also be considered as conditions that minimize yield loss due to the transition to the spent sulfuric acid solution. . Thus, the catalytic cracking boiling range effluent is usually in an amount greater than about 70 wt%, preferably greater than about 80 wt%, more preferably greater than about 90 wt%, based on the cat cracker feed stream. The remainder is contained in the spent sulfuric acid solution separated from the catalytic cracking boiling range effluent. While not wishing to be bound by theory, the inventors believe that this yield loss is attributed to compounds such as coke precursors, tetracyclic aromatic compounds and polar compounds. It should be noted that if necessary, the catalytic cracking boiling range effluent contained in the separated spent sulfuric acid solution can be recovered and combined as a recycle stream into the catalytic cracking boiling range feed stream.

  In catalytic cracking boiling range effluents, the nitrogen content is usually reduced both basic and non-basic compared to the original catalytic cracking boiling range feed stream. The nitrogen content of the catalytic cracking boiling range feed stream is removed in an amount greater than about 60 wt%, preferably greater than 75 wt%, more preferably greater than 90 wt%. Therefore, in the catalytic cracking boiling range effluent, the nitrogen content is reduced by 60% by weight compared to the catalytic cracking boiling range feed stream.

  For catalytic cracking boiling range effluents, the total metal concentration, such as, for example, the sum of Ni, V, Fe, Cu, and Na metals, is also typically lower than the original catalytic cracking boiling range feed stream. The total metal concentration in the catalytic cracking boiling range product is usually about 20 wppm to about 1000 wppm, preferably about 10 wppm to about 500 wppm, more preferably about 5 wppm to about 30 wppm.

  In a preferred embodiment, at least a portion of the first reaction stage effluent or catalytic cracking boiling range effluent is sent to a suitable catalytic cracking operation. Suitable catalytic cracking operations include, but are not limited to, fluid catalytic cracking and hydrocracking. In the catalytic cracking operation used, any suitable catalytic cracking catalyst can be used to obtain the desired product. In the present invention, the conditions under which the first reaction stage effluent comes into contact with the cracking catalyst are not critical and may be any conditions as long as they are effective in producing the desired product, i.e., naphtha, diesel, and the like. Thus, in the practice of the present invention, the practitioner selects a single or multiple catalysts and then selects conditions effective for this particular catalyst. For example, if the catalytic cracking boiling range product is sent to a fluid catalytic cracking (“FCCU”) reactor, any FCCU catalyst can be used and the FCCU reactor is operated at conditions effective for that particular catalyst. Will. Similarly, if the catalytic cracking range product is sent to a hydrocracking reactor, a suitable hydrocracking catalyst such as zeolite is selected, for example, hydrocracking reactor such as hydrotreating rate, liquid space velocity, etc. These conditions will be selected from conditions known to be effective for that particular single or multiple catalysts.

  Note that this nitrogen removal method also benefits downstream catalytic processes such as desulfurization used for products produced in catalytic cracking operations such as naphtha and diesel boiling range products. . It should also be noted that the catalytic cracking boiling range effluent typically has a lower sulfur concentration than the nitrogen-containing catalytic cracking boiling range feed stream. Thus, contacting the catalytic cracking boiling range feed stream with the sulfuric acid solution also reduces the sulfur content in the catalytic cracking boiling range effluent. Thus, the catalytic cracking boiling range effluent will have a lower sulfur concentration than the catalytic cracking boiling range feed stream. However, it is desirable to minimize sulfur removal to minimize yield loss. The sulfur content of the catalytic cracking boiling range effluent is usually about 0.1 to about 25%, preferably about 0.1 to about 15%, more preferably about 0.1 to about 10 from the catalytic cracking boiling range feed stream. %, Most preferably about 0.1 to about 5% lower.

  The above description is that of the preferred embodiment of the invention. Those skilled in the art will recognize that other embodiments that are equally effective may be devised to implement the spirit of the invention.

  The following examples illustrate the improved effectiveness of the present invention and do not limit the invention in any way.

Example 1
Three 20 ml straight run gas oil samples were diluted with 5 ml toluene to reduce the viscosity at room temperature and mixed with sulfuric acid solution in a glass centrifuge tube. To one sample, 0.4 ml of a sulfuric acid solution for reagent having a sulfuric acid concentration of 96% by weight (a treatment rate of 2% by volume) was added. This sulfuric acid solution is referred to herein as Solution # 1. The other two samples were mixed with the same sulfuric acid solution, and the volume was 0.8 ml (4% by volume treatment rate) and 20 ml (10% by volume treatment rate), respectively. The mixture was shaken by hand for 60 seconds and then allowed to separate at room temperature. The two phases were separated into a cat cracker boiling range product and a sulfuric acid solution, and the cat cracker product layer was removed. The cat cracker product thus removed was stripped in vacuo to remove toluene, weighed, and analyzed for nitrogen content by ANTEK. The results of this experiment are shown in Table 1 below.

Example 2
The same straight gas oil feed stream as in Example 1 was processed according to the method described in Example 1 above. In this experiment, however, the sulfuric acid solution mixed with straight run gas oil is spent sulfuric acid recovered from the alkylation process equipment and is referred to herein as acid solution # 2. The spent sulfuric acid had a composition consisting of 90% by weight sulfuric acid, 4% by weight water and 6% by weight acid-soluble hydrocarbon. When this is converted into the equivalent sulfuric acid strength defined above, it is 96% by weight. 1 ml (5% by volume treatment rate) and 20 ml (10% by volume treatment rate) sulfuric acid solution # 1 and sulfuric acid solution # 2 were separately mixed with the straight-run gas oil feed stream. The results of this experiment are shown in Table 2 below as a comparison of the treatment with sulfuric acid solutions # 1 and # 2.

  As can be seen from Table 1, the raw material showed a good response to the treatment with both acid solutions. It should also be noted that there is some advantage in raw material recovery at a 5 vol% treat rate using spent sulfuric acid solution.

Claims (22)

An improved catalytic cracking method,
a) providing a sulfuric acid solution containing sulfuric acid in an amount greater than 75% by weight;
b) In the first reaction stage, the nitrogen-containing catalytic cracking boiling range feed stream, under effective conditions, with an acid solution volumetric treatment rate of more than 0.5% by volume based on the catalytic cracking boiling range feed stream, Contacting with a sulfuric acid solution to produce a first reaction stage effluent comprising at least a catalytic cracking boiling range effluent and a spent sulfuric acid solution, wherein the weight of nitrogen compounds contained in said catalytic cracking boiling range feed stream And wherein c) directing at least a portion of the first reaction stage effluent to a second reaction stage where the first reaction stage effluent contacts a cracking catalyst under effective cracking conditions. A catalytic cracking method comprising:   The catalytic cracking method of claim 1, wherein the nitrogen-containing catalytic cracking boiling range feed stream reaches a boiling point at 430 ° F. to 1050 ° F. (220 to 565 ° C.).   The nitrogen-containing catalytic cracking boiling range feed stream is a heavy hydrocarbon oil containing material with a boiling point greater than 1050 ° F. (565 ° C.); heavy and extracted petroleum-based crude oil; petroleum atmospheric residue; petroleum vacuum residue; Or asphalt, bitumen or other heavy hydrocarbon residue; tar sand oil; shale oil; liquid product from coal liquefaction process; light or heavy cycle oil; and mixtures thereof 2. The catalytic cracking method according to 2.   The catalytic cracking method according to any one of claims 1 to 3, wherein the nitrogen-containing catalytic cracking boiling range feed stream comprises a vacuum gas oil having a boiling point exceeding 650 ° F (343 ° C).   5. The catalytic cracking method according to claim 1, wherein the nitrogen-containing catalytic cracking boiling range raw material stream contains 100 to 10,000 wppm of nitrogen.   6. The catalytic cracking method according to claim 1, wherein the total metal concentration of the nitrogen-containing catalytic cracking boiling range feed stream is 10 wppm to 1000 wppm.   Nitrogen present in the nitrogen-containing catalytic cracking boiling range feed stream is quinolines, substituted quinolines, benzoquinolines, anilines, N-alkylindoles, alkylarylamines and substituted derivatives thereof, indoles and carbazoles. The catalytic cracking method according to claim 1, wherein the catalytic cracking method is selected from the group consisting of:   The catalytic cracking method according to claim 1, wherein the sulfuric acid solution contains sulfuric acid in an amount exceeding 80% by weight. The sulfuric acid solution is
a) combining an olefinic hydrocarbon feedstream comprising C ₃ -C ₅ olefins with isobutane to produce a hydrocarbonaceous mixture; and b) said hydrocarbonaceous mixture comprising an alkylate and an acid concentration of at least 75% by weight. The catalytic cracking method according to any one of claims 1 to 8, which is a sulfuric acid solution obtained by a step of contacting with sulfuric acid under a condition effective to produce at least a sulfuric acid solution having a water content.   The catalytic cracking method according to any one of claims 1 to 9, wherein more than 75 wt% of the nitrogen compound contained in the catalytic cracking boiling range raw material stream is removed.   The catalytic cracking method according to any one of claims 1 to 10, wherein a treatment rate of the sulfuric acid solution is 0.5 to 20% by volume.   12. The catalytic cracking boiling range feed stream and the sulfuric acid solution are intimately contacted by a non-dispersive contact method selected from the group consisting of a packed bed of inert particles and a fiber film contactor. The catalytic cracking method in any one of.   The catalytic cracking boiling range feed stream and the sulfuric acid solution are intimately contacted by a method selected from the group consisting of a mixing valve, a mixing tank or vessel, a propeller mixer, an in-line static mixer and an orifice plate. The catalytic cracking method in any one of 1-12.   Separating the first reaction stage effluent into at least the catalytic cracking boiling range effluent and the spent sulfuric acid solution by any means known to be effective in separating acids from hydrocarbon streams. The catalytic cracking method according to any one of claims 1 to 13.   The catalytic cracking boiling range effluent and the spent sulfuric acid solution are separated by a separation device selected from the group consisting of a sedimentation tank or drum, coalescer, electrostatic precipitator and similar devices. The catalytic cracking method in any one of 1-14.   The catalytic cracking method according to claim 1, wherein the catalytic cracking boiling range effluent and the spent sulfuric acid solution are separated by a fiber film contactor.   The catalytic cracking method according to any one of claims 1 to 16, wherein a total metal concentration of the catalytic cracking boiling range effluent is lower than that of the catalytic cracking boiling range feed stream.   The catalytic cracking method according to any one of claims 1 to 17, wherein a total metal concentration of the catalytic cracking boiling range effluent is 20 wppm to 1000 wppm.   The catalytic cracking method according to claim 1, wherein water is added to the sulfuric acid solution to adjust a sulfuric acid concentration of the sulfuric acid solution.   The catalytic cracking method according to any one of claims 1 to 19, wherein the sulfur content of the catalytic cracking boiling range effluent is 0.1 to 25% lower than the catalytic cracking boiling range feed stream.   The catalytic cracking method according to any one of claims 1 to 20, wherein a yield loss caused by the sulfuric acid solution treatment is 0.5 to 30% by weight. An improved catalytic cracking process comprising the step of removing nitrogen from a nitrogen-containing catalytic cracking boiling range feed stream comprising:
a) providing a sulfuric acid solution containing sulfuric acid in an amount greater than 80% by weight;
b) In the first reaction stage, a nitrogen-containing catalytic cracking boiling range feed stream having a boiling point of 430 ° F. to 1050 ° F. (220 to 565 ° C.) is based on the catalytic cracking boiling range feed stream under effective conditions. A first reaction stage effluent comprising at least a catalytic cracking boiling range effluent and a spent sulfuric acid solution at a treatment rate of 0.5 to 20% by volume of an acid solution. Removing more than 75% by weight of the nitrogen compounds contained in the catalytic cracking boiling range feed stream, wherein the contacting is carried out by a contacting method selected from the group consisting of non-dispersed and dispersed contacting methods; and c) Including at least a portion of the first reaction stage effluent to a reaction stage where the first reaction stage effluent contacts a cracking catalyst under effective cracking conditions. Catalytic decomposition method.