Multipurpose catalytic distillation column and method of esterification using this column

 

(57) Abstract:

The invention can be applied to obtain tertiary mileticova ether (tame) by interaction of isoamylenes contained in the products of the cracking of light naphtha, methanol. Two reaction distillation zone is situated above the distant sections. This distillation in addition to uninstalling tame also removes C6and heavier components. The first distillation reaction zone contains a catalyst for Hydrotreating to remove diolefins and mercaptans. The second distillation reaction zone contains acidic cation exchange resin for the esterification reaction. The entire column is used for the fractionation of multicomponent reaction system (reagents, inert compounds, products and impurities) simultaneously with multiple reactions. 2 S. and 6 C.p. f-crystals, 1 Il.

The invention relates to a multipurpose catalytic distillation column and use that column to obtain the ether, through interaction isoolefine with alcohol. More specifically, this invention relates to the production of tertiary amyl methyl ether, through interaction of isoamylenes contained in products to obeserved raw materials by removing mercapto, removed the NITRILES of raw materials, selectively hydronauts diene contained in raw materials and reacting isoamylene with methanol, to obtain tertiary amyl methyl ether.

Fraction C5when processing oil is a valuable raw material as a component of gasoline or source isoamylenes order to obtain an ether by reaction with lower alcohols. Tertiary amyl methyl ether (tame) is a valuable product of oil refining in the recently adopted Resolution on clean air, which set new limits for components of gasoline. Some of these requirements are: (1) the inclusion of a certain number of "oxygen", such as methyl-tertiary butyl ether (MTBE), tertiary amyl methyl ether or ethyl alcohol, (2) reduction of olefins in gasoline, and (3) reduction in vapour pressure (volatility).

In most fractions of C5isoamylene suitable for tame production, often present in small amounts, for example, less than 15%, and at the same time there are other isomers of aleinov C5and a sufficient amount of dienes and acetylenes to suppress the process of esterification.

In the US 5196612 A, 23.03.1993 opisi column reactor, stages flow easy crackerandoj naphtha and stream containing methanol in a distillation column reactor, which is more close analog of the invention.

An advantage of the present invention is that impurities such as diolefine, acetylene, mercaptans and NITRILES, are removed by esterification in a single distillation column reactor. Another advantage is that the air stream exiting the column is suitable as octane component of gasoline without further processing. These and other advantages and features of the present invention will become apparent from the further description.

The present invention includes a single distillation column reactor into which flows crackerandoj light naphtha to obtain tertiary amyl methyl ether. The distillation column reactor is depentanizer, in order to remove the fraction of C6and above, and because at the same time served methanol azeotrope is the selection of NITRILES from fraction C5. For all the desired reactions are appropriate layers of the catalytic distillation structure. In the first SL is, is the quiet can be removed with a bottom fraction C6and selective hydrogenation of diolefins raw material and the second layer flows etherification.

The method according to the invention to obtain tertiary amyl methyl ether involves the following stages:

a) feeding a first stream containing light crakereanda naphtha, distillation column reactor having a distant section of the first distillation reaction zone containing a hydrogenation catalyst in the form of a catalytic distillation structure, and a second distillation reaction zone containing acidic cation exchange resin in the form of a catalytic distillation structure;

b) simultaneously feeding a second stream containing hydrogen, and a third stream containing methanol, specified in the distillation column reactor;

C) separation of fraction C6and higher boiling fractions from the specified light crackerandoj naphtha specified in distant sections, at that time, as a fraction of C5boils in this first distillation reaction zone;

g) simultaneously, in the first distillation reaction zone:

1) removes sulfur compounds, which are primarily mercaptans by reacting Merck is the fraction of C5with the formation of sulfides with higher intervals boiling than the specified wikipeida fraction C5,

2) other diolefine and any acetylene contained in this wikipeida fraction C5interact with part of the specified hydrogen, reducing the degree of unsaturation and isomerize part of isoolefine, and

3) is formed azeotrope of C5/methanol, which Argonauts specified in the second distillation reaction zone, while these sulfides and nitrogen-containing compounds present in this fraction C5are removed by fractional distillation,

d) simultaneously in this second distillation reaction zone,

1) isoamylene contained in the azeotrope, interact with methanol from this azeotrope with the formation of tertiary amyl methyl ether and

2) this tertiary amyl methyl ether is separated from the unreacted carbon C5and methanol by fractional distillation;

e) removing unreacted hydrocarbon, C5and methanol and unreacted hydrogen from the specified distillation column reactor in the form of the upper shoulder strap, and

g) removal of this fraction C6and heavier fractions of the order the columns of the reactor in the form of bottom residue.

High-boiling components above the stage) include tertiary amyl methyl ether, sulfides and NITRILES, which are eventually removed from the reactor column as a bottom fraction.

The drawing shows a simplified diagram of a catalytic distillation column having a configuration according to the invention.

Stream C5in raw materials for this installation for tame contained in a single faction "light naphtha" which can include everything from C5to C8and above. This mixture may contain from 150 to 200 components. Mixed refinery streams often contain a wide range of olefinic compounds. This is especially true for the products of the catalytic or thermal cracking. Refinery streams are usually separated by fractional distillation, and this separation is not clear, because they often contain compounds that have very similar boiling point. For example, the flow of C5may contain hydrocarbons from C4to C8. These components can be saturated (alkanes), unsaturated (monoolefinic) or polyunsaturated (diolefin). In addition, these components can be any of various isomer>Some of impurity components (diolefin) may slowly to interact with oxygen during storage with the formation of "tar" and other unwanted materials. However, these components are also very responsive in terms of the process of obtaining tame, forming a yellow resinous material with a bad smell. Thus, it is desirable to remove these components, regardless of whether the use of "light naphtha" directly to compounding fuel or as raw material for the process of obtaining tame.

Such refinery streams also contain small quantities of sulfurous and nitrogenous compounds, which must be removed. Sulfur compounds are generally represented in the flow of light crackerandoj naphtha in the form of mercaptans, which interact with the catalyst of esterification, inhibiting the reaction of esterification. Nitrogen-containing compounds are usually in the form of NITRILES, which can be either hydrolyzed to form compounds having a basic nature, and can neitralizovat the acid sites of the catalyst of esterification. Thus, the removal of mercaptans and NITRILES is desirable.

The nature of the sulfur present is connected to the C) the predominant sulfur compounds are mercaptans. Typical mercaptane compounds that can be found to a greater or lesser extent in light crackerandoj nafta is methylmercaptan (T boil 43oF), ethyl mercaptan (T boil 99oF), n-propylmercaptan (T boiling 154oF), ISO-propylmercaptan (T boiling 135-140oF), ISO-butylmercaptan (T boiling 190oF), tert-butylmercaptan (T boiling 147oF), n-butylmercaptan (T boiling 208oF) second-butylmercaptan (T boiling 203oF), isoamylalcohol (T boiling 259oF), alpha methylbutyrate (T boiling 234oF), alpha ethylpropylamine (T boiling 239oF), n-exillerating (T boiling 304oF), 2-mercaptohexyl (T boiling 248oF), and 3-mercaptohexyl (T boiling 135oF).

Typical diolefine, wikipaedia in the range of fractions of C5include isoprene (2-methylbutadiene-1,3), CIS - and TRANS-piperylene (CIS - and TRANS-pentadiene-1,3) and a small amount butadiene.

Suitable raw material for the present invention may be a light naphtha fraction comprising primarily hydrocarbons, C5including normal alkanes, normal alkenes, isoalkanes and isoalkane and a very small amount of impurity compounds containing sulfur and nitrogen.


1) etherification,

2) distillation of unreacted components C5from the product of esterification,

3) separation of components C5from nitrile impurities by azeotropic distillation of alcohol and C5,

4) hydrogenation of diolefins and acetylenes,

5) removal of sulfur compounds, including the interaction of mercaptans with diolefine,

6) isomerization of isoolefine,

7) distillation of the components of C5from sulphides,

8) distillation of the lighter components from the essential product components C6and heavier hydrocarbons, NITRILES and sulfides.

Referring to the drawing, it is possible to understand the operation of the column and fashion. It is shown that the distillation column reactor 10 is substantially cylindrical in shape and is oriented vertically. Enter methanol 2 is provided near the lower end of zone 12. In the lower part 20 of the vessel containing inert distillation structure, such as an inert packing, sieve trays, bubble cap plates or similar Section 20 is a distant section of the Department of C6and higher boiling materials from C6and lower boiling materials in the light crackerandoj nafta. The input light crecerelle it is served with a light naphtha.

Directly above the distant sections inside the column 10 is first distillation reaction zone 7, containing a hydrogenation catalyst, which may be contained in an open mesh conveyor belt, is wound inside demister of wire mesh and prepared as the first catalytic distillation structure. Section 7 is a hydrogenation zone where diolefine and acetylene selectively hydronauts, mercaptans interact with diolefine and the isomerized isoolefine. Isomerization under the conditions of hydrogenation occurs at the double bond and skeletal isomerization occurs to a minor extent, if at all occurs in this process. Sulfides formed by the interaction of mercaptans with diolefine, boil higher than the components of C5and are distilled below and removed from the bottom fraction.

Hydrogenation is the interaction of hydrogen with carbon-carbon multiple bond with the "saturation" of the connection. Typically, this reaction proceeds at pressures above atmospheric and moderate temperatures using an excess of hydrogen on the metal catalyst. Known metals that catalyze the hydrogenation reaction are platinum, R. deposited oxides of these metals. These oxides are recovered in active form or to use regenerating agent, or in use under the action of hydrogen in the raw material. These metals also catalyze other reactions, the most significant reaction hydrogenation at elevated temperatures. In addition, they contribute to the interaction of olefinic compounds with each other or with other olefins to form dimers or oligomers, when increasing the residence time.

Selective hydrogenation of hydrocarbon compounds known for a long period. Peterson and others in the "Selective hydrogenation of pyrolysis gasoline", presented at the Petroleum division of the American chemical society in September 1962, discussed the selective hydrogenation of C4and the highest diolefines, Boatie and others in the "Latest hydrogenation catalysts", Hydrocarbon Processing, March, 1985, presented an overview of different applications of catalytic hydrogenation, including selective hydrogenation, using proprietary bimetallic catalyst for the hydrogenation, which is also suitable for the present invention.

In the first distillation zone 7 reactions of interest is the IP - and TRANS-pentadiene-1,3/CIS - and TRANS-piperylene/ penten-1 and penten-2,

3) hydrogenation of 1,3-butadiene to butene-1 to butene-2,

4) interaction of mercaptans with denami

< / BR>
5) isomerization between 3-methylbutanol and 2-methylbutanol-1/2-methylbutanol-2.

A suitable catalyst for the partition hydrogenation catalyst 7 is to 0.34 wt.% palladium on alumina in size from 3 to 8 mesh, which is supplied by the company United Catalysts Inc., and is denoted as g-si. The following are typical physical and chemical properties of the catalyst, guaranteed by the manufacturer:

Designation - g-si

Shape - Spherical

Normal size - 5 x 8 mesh

Palladium weight. wt. - 0.3 to (0,27-0,33)

Media - alumina of high purity

I believe that the catalyst is a palladium hydride, which is formed during operation. The rate of hydrogen in the reactor should be sufficient to maintain the catalyst in active form, as the catalyst loses hydrogen during hydrogenation, but is maintained below that value, which can lead to zachlapywaniu columns. It is understood that this speed corresponds to the "effective amount of hydrogen", and this term is used in the description. The usual molar ratio of hydrogen to disrepectful 2,0:1,0.

Other suitable catalysts for the hydrogenation/isomerization and esterification include macroporous or gel-like acidic cation exchange resin in the proton form, which entered the metal of group VI, VII or VIII of the Periodic table of elements, as described in U.S. patent N 4330679.

This catalyst must be appropriately marked and located inside the column to act as a catalytic distillation structure. In a preferred variant embodiment, the catalyst is contained in a coiled wire mesh structure, as described in application for U.S. patent, serial number 901771, filed June 22, 1992, and N 075320, filed January 15, 1993, which is included as reference material. Other catalytic structures suitable for use in the present method, described in U.S. patent N 4731229, 5073236 and Europatent N 0396650.

Above section hydrogenation, inside the column 10 second distillation reaction zone 12 contains the acid catalyst is a cation exchange resin in the form of a second catalytic distillation structure. In this section 12 isoamylene interact with methanol, to form tertiary amyl methyl ether (tame), which boils viseo line 8. Area 12 may be located directly above zone 7 or there may be intermediate inert distillation structure (not shown), as described in the zone 20.

In addition, methanol and components C5form an azeotrope which boils lower than the components of C5and nitrile impurities. Had this azeotrope boils from the first reactive distillation zone 7 in the second reaction distillation zone 12. In the azeotrope of isoamylene interact with methanol education tame.

In the case of components C5the azeotrope contains about 12 wt.% methanol, and the boiling point of this azeotrope 10-15oF (6-9oC) lower than the boiling point of C5. Thus, if the total flow of methanol to the column (whereas methanol, reacting in the column) is lower than the azeotropic concentration in the distillate, the concentration of methanol in the reaction distillation zone is very low, about 1%. If the total flux of methanol in the column is higher than the azeotrope, the concentration of methanol will increase up until the methanol will be used with the bottom product of tame. None of these cases is not desirable, because at low concentrations stepl due to the presence of excess methanol. Thus, the feed rate of methanol is continuously regulated to hold the amount of methanol in the column is higher than the azeotrope, but below an excessive number appearing in the bottom fraction. In one embodiment, this embodiment can be set by feeding part of methanol above the layer of the catalyst of esterification on line 14.

The azeotrope of methanol/C5(without nitrogen compounds and sulphides), drives away in section of esterification 12, which contains the acid catalyst is a cation exchange resin in the form of a catalytic distillation structure. The process of esterification is such as described in U.S. patent N 4336407 included as reference material. In General, the particle size of the resin is such that it is preferable for the fine mesh, such as a fabric container. Such container and catalytic distillation structure disclosed in U.S. patent N 4443559, which is included as reference material, and as shown, includes a tape from fiberglass with many cavities containing the resin - catalyst. This fabric tape can be wound with demister wire mesh and is distillation structure.

Unreacted methanol, the components of Cthe materials, capable of condensation, and then going on line 4 in the drive-separator 11. The third set of inert distillation structures 15 optional is located above the second reaction distillation zone 12. Light non-condensable materials, including hydrogen, are removed from the drive line 3. The liquid is removed from the separator through line 9, and part of its recycle to the column 10 by line 6 in the form of phlegmy.

Tertiary ethyl methyl ether is usually not separated from the heavier components, and all the mixture is used directly as a high-octane additive.

1. The distillation column reactor comprising a vertical cylindrical vessel, inert distillation structure, located in the lower part of the vessel, the first distillation reaction zone containing a first catalytic distillation structure located in the interior of the vessel directly above the inert distillation structure, the second distillation reaction zone containing a second catalytic distillation structure located in the interior of the vessel above the first distillation reaction zone containing a catalyst of esterification, wherein the first katal the district column under item 1, characterized in that the hydrogenation catalyst contains deposited on the alumina granulated palladium oxide catalyst contained in an open mesh container, wrapped inside of demister of wire mesh.

3. Distillation column under item 1, characterized in that the esterification catalyst contains acidic ion-exchange resin contained in the cavities on the ribbon of tissue and wound together with demisters of wire mesh.

4. Distillation column under item 1, characterized in that the hydrogenation catalyst contains deposited on the alumina granulated palladium oxide catalyst contained in an open mesh container, wrapped inside of demister of wire mesh, and the esterification catalyst contains acidic ion-exchange resin contained in the cavities on the ribbon of tissue and wound together with demisters of wire mesh.

5. The method of processing flow easy crackerandoj naphtha containing isoamylene, using a distillation column reactor and flow easy crackerandoj naphtha and stream containing methanol in a distillation column reactor, wherein serves stream legrow and second distillation reaction zone, at the same time serves stream containing hydrogen to a distillation column reactor, separating the fraction C6and heavier boiling fraction from the light crackerandoj naphtha in distant sections when boiling boiling fraction C5containing the mercaptan and diolefine pollution up in the first distillation reaction zone, in which simultaneously the mercaptans contained in boiling fraction C5interact with a part of diolefins contained in boiling fraction C5with the formation of sulfides with higher intervals boiling point than the boiling fraction C5other diolefine and any acetylene contained in boiling fraction C5interact with a part of the hydrogen is separated boiling fraction C5from sulphides by fractional distillation, served containing methanol stream to a distillation column reactor with the formation of the first distillation reaction zone azeotrope methanol/C5having a lower boiling point than the boiling fraction C5, distilled azeotrope up to the second distillation reaction zone, in which part of isoamylenes contained in the azeotrope, interacts with a part of the methanol contained in the azeotrope, OBR is agelou boiling fraction and sulfides from the distillation column reactor in the form of bottom residue.

6. The method according to p. 5, wherein any nitrogen-containing compounds from fraction C5remove the bottom fraction.

7. The method according to p. 5, characterized in that for obtaining tertiary amyl methyl ether first distillation reaction zone comprises a hydrogenation catalyst in the form of a catalytic distillation structure and a second distillation reaction zone comprises an acidic cation exchange resin in the form of a catalytic distillation structure.

8. The method according to p. 5, characterized in that the part of the methanol serves above the second distillation reaction zone.

 

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