Catalyst for reducing the benzene content in gasoline fractions and the way to reduce the benzene content in gasoline fractions

 

(57) Abstract:

Catalyst for reducing the benzene content in gasoline fractions for the isomerization of hydrocarbons contains 4-15% of a halogen and a metal of group VIII supported on a carrier, which consists of ataxia aluminum and gamma-alumina. The use of this catalyst in the method of reducing the content of benzene in gasoline fractions allows to obtain effluent, almost completely devoid of benzene and having a higher octane number, which allows us to include it in the gasoline fraction after stabilization. 2 C. and 10 C.p. f-crystals, 4 PL.

The invention relates to the field of catalytic isomerization of paraffins. In particular, the invention relates to a catalyst for isomerization of paraffins and to a method of catalytic isomerization of paraffins with the aim of obtaining gasoline fractions with low benzene content.

Problems related to environmental protection during fuel use, are at the same time to reduce the lead content and the reduction of the benzene content in gasoline, preferably without reducing the octane number. Catalytic reforming is used in very harsh conditions, and isomerize what riesame to obtain gasoline with a high octane number without additives lead. However, the method of catalytic reforming leads to significant quantities of benzene with a high octane number. That is why it is necessary to develop new processes that reduce benzene content in fuels, meeting the requirements for the octane number.

There is a method that combines catalytic reforming and isomerization, which consists in the separation of fraction C5-C6the reformate, isomerization, and in the introduction it directly into a gasoline fraction to improve the octane number: it is described, for example, in U.S. patents 457832, 4181599, 3761392. Also known isomerizing treatment fraction C5-C6, obtained by direct distillation of crude oil. It leads to a significant improvement in the octane number of this fraction. The decrease in the content of benzene in the reformate can also be implemented in other ways, such as, for example, modifying the temperature of the distillate fractions between naphtha reforming and isomerization, or separation reforming into two fractions: a heavy fraction (heavy reformate) and light fraction (light reformate), and all the benzene is concentrated in a specified light fraction. This light fraction is then sent to the installation of hydrogenation, where turn benzene in n the ins, thus obtained, will isomerized according to the classical method of isomerization (U.S. patent 5003118). In addition, the application for the European patent EP-A-552070 described method of reducing the content of benzene in gasoline fractions, which carried out the hydrogenation of the load, consisting of 40 to 80% of paraffins, 0.5 to 7% of cyclic hydrocarbons and 6 to 45% of aromatics, and having a maximum distillation temperature lying between 70oand the 90oC, then carry out the isomerization hydrogenation products when mixed with a specified load and/or effluent fraction C5-C6.

European patent application EP-A-552069 describes a method of isomerization of load, such as a light reformate and/or fraction C5-C6in the presence of isomerization catalyst, which preferably contains at least one metal of group VIII and modernit with a ratio Si/AI, lying between 5 and 50.

In U.S. patent 3025248 describes how to obtain a catalyst carrier which is based on alpha - and beta-alumina treated in this way to turn these oxides of aluminium in this - and gamma-aluminum oxide. The catalyst also contains minor amounts of platinum or other metal, such as palladium, Nickel, VC is which can be used in particular, methods for reducing the benzene content in gasoline fractions.

The proposed catalyst consists of a carrier, representing ETA-alumina and gamma-alumina, and the content of this alumina is 85 to 95 wt.%, preferably 88 to 92 wt.%, and more preferably 89 to 91 wt.%, the rest up to 100 wt.% the media has essentially of gamma alumina, the said catalyst also contains 4 to 15%, preferably 6 to 15%, more preferably 6 to 11% of at least one halogen, preferably chlorine, and at least one metal of group VIII.

This is the aluminum oxide used in the present invention has a specific surface area, usually part of 400 - 600 m2/g, preferably 420 - 550 m2/g and total pore volume of 0.3 - 0.5 cm3/g, preferably 0.35 to 0.45 cm3/,

Gamma-alumina typically has a specific surface area of 150 to 300 m3/g, preferably 180 to 250 m2/g and total pore volume of 0.4 - 0.8 cm3/g, preferably 0,45 - 0,7 cm3/,

Two types of aluminum oxide are mixed and formed into the above proportions by any known method, for example, by extrusion through a die plate, pelletizing or Tagirova the 2/g, preferably 350-500 m2/g and pore volume of 0.3-0.6 cm3/g, preferably 0.35 to 0.5 cm3/,

At least one hydrogenating metal of group VIII, preferably selected from the group consisting of platinum, palladium, Nickel, is applied on the carrier by any known specialist way, for example, anionic exchange, in the form of hexachloroplatinic acid in the case of platinum or in the form of chloride in the case of palladium.

In the case of platinum or palladium mass content is 0.05-1%, preferably 0.1 to 0.6%. In the case of the Nickel mass content is 0.1-10%, preferably 0.2 to 5%.

Thus prepared catalyst is reactivated by hydrogen, then put Ganoderma processing any halide compound, known to the specialist. In the case of chlorine halide such connection may be carbon tetrachloride or perchlorethylene. The content of the halogen, preferably chlorine, in the finished catalyst is from 4 to 15%, preferably 6-15%, even more preferably 6 to 11%.

This Ganoderma processing can be carried out in the unit before the introduction of the boot or not. It is also possible to halogenous processing before vestenamer, in the method of reducing the content of benzene in gasoline fractions, which carry out the isomerization feedstock, such as a light fraction from the reformate and/or fraction C5-C6coming straight after distillation. Thus unexpectedly receive effluent, almost completely devoid of benzene (i.e., containing less than 0.1 wt.% benzene) and having a higher octane number or equal to the desired octane number of the light reformate, which allows us to include it in the gasoline fraction after stabilization.

Light fraction of the reformate obtained from the distillation of the specified reformate. It is determined by the maximum distillation temperature lying between 70oand the 90oC, preferably between 77o83oand mass composition of the hydrocarbons found in the following intervals: 40,0 80% of paraffins, 0.5 to 7.0 percent cyclic hydrocarbons (such as Methylcyclopentane, cyclopentane or cyclohexane) and 6.0 - 45% of aromatics. The distillation temperature is usually between room temperature and a maximum distillation temperature (or the temperature of the head of the faction).

The group of aromatic hydrocarbons usually consists mainly of benzene. In addition, in the aforementioned light fraction may present the average molecular weight of the specified fraction is 70 - 90 g/mol, bulk density, measured at the 15oC is 0,670 - 0,780 g/cm3and the desired octane number is 75 - 90.

Can also be used any other hydrocarbons originating from another process or set of processes and characterized by mass composition in the following intervals: 40 to 80% of paraffins, 0.5 to 7% of cyclic hydrocarbons and 6 to 45% of aromatics, and a maximum distillation temperature between 70oand the 90oC, preferably between 77o83o.

Mass composition of the above fraction C5-C6that is usually obtained after direct distillation depends on the nature of the processed raw materials.

However, the specified fraction is usually defined paraffin content is usually above 90 wt.%, the content of cyclic hydrocarbons usually below 10 wt.% and benzene content is usually less than 1.5 wt.%. Its octane number is usually 60 to 75.

On the other hand, this fraction may contain very small amounts of compounds containing 4 carbon atoms in the molecule (less than 0.5 wt.%).

According to the present invention mix the two above-described raw materials, then send them together in the installation isplay 15 - 55%.

Usually prepared in advance to the mixture was added the compound of chlorine, such as carbon tetrachloride or perchlorethylene, before entering the isomerization zone so that the content of chlorine in the raw materials ranged from 50 to 5000 million-1, preferably 100 to 1000 million-1.

The isomerization zone is under the conditions usual for isomerization. It is conducted in at least one reactor.

Temperature is 100 - 300oC, preferably 120 to 250oC, and the partial pressure of hydrogen is between atmospheric pressure and 70 bar, preferably between 5 and 50 bar. The volumetric feed rate is 0.2 - 10 l, preferably 0.5 to 5 liters of liquid hydrocarbons per liter of catalyst per hour. The molar ratio hydrogen/feedstock at the inlet of the reactor is such that the molar ratio hydrogen/feedstock into an output stream above 0.06, preferably it is between 0.06 and 10.

Thus obtained stabilized output stream has a sufficiently high octane number, allowing you to enter it into a gasoline fraction after stabilization, and he almost does not contain benzene (benzene content in the output stream below 0.1 wt.%.

Given the reformate, obtained after distillation at 80oC, containing 21.5% of the benzene and having an octane rating of 80.3, mix at the rate of 50 wt.% fraction C5-C6direct distillation, containing 0.7% of benzene and having an octane number of 65. The composition of these two products are given in table 1. Light reformate, therefore, contains a 21.5 wt.% aromatics, 4% of cyclic hydrocarbons and 74.5% of the paraffins. Fraction C5-C6contains 0.7 wt.% benzene, to 7.25 wt.% cyclic hydrocarbons and 92,05 wt.% paraffin. The mixture of these two types of material, the composition of which is also shown in table 1, is sent to the isomerization unit at a temperature of 170oC, a pressure of 30 bar with a bulk velocity equal to 2 liters of liquid hydrocarbons per liter of catalyst per hour, at a molar ratio hydrogen/hydrocarbons such that the same ratio is 0.07 in output stream.

The used catalyst is from 0.3 wt.% Pt supported on a carrier, representing 90% of this-alumina and 10 wt.% gamma-alumina. Defined in this way, the catalyst then glorious at the rate of 9 wt. % chlorine. The flow coming from the isomerization unit, has the composition shown in table. 1. It contains practically no more benzene and octane has a invention). Prepare six standard catalysts A - F, consisting of a 0.3% Pt supported on a carrier which is a mixture of ETA-alumina and gamma-alumina, the content of this-alumina in the carrier varies from 85 to 95%, as indicated in table 2. Defined this way catalysts glorious at the rate of 9 wt.% chlorine. The raw material is introduced into the isomerization, the composition of which is given in table. 1, is sent to the isomerization unit, operating in the conditions described in example 1. The octane number obtained after isomerization, are shown in table 2. It is established that the maximum octane number obtained when the content of this-alumina carrier between 89% and 91%.

Example 3 (according to the invention). This example differs from example 1 only in that the catalyst specified in example 1, hairout the rate of 7 wt.% chlorine.

The flow coming from the isomerization unit, has the composition shown in table. 3. It does not contain benzene and has an octane rating of 80.3. Therefore, it can be directly entered in the gasoline fraction after stabilization.

Example 4 (comparative). Example 4 differs from example 3 only in that used in the area of the isomerization catalyst contains 0.3 th thus the catalyst was then subjected gloriouse processing. The final chlorine content equal to 7 wt.%.

In table. 4 has been part of the flow coming from the isomerization unit.

The increase in the octane number between feedstock in the isomerization unit and moving out of the stream is very low. There is a decrease in the octane number relative to the light reformate.

Note: in the above tables

2,2 VHI4= 2.2-Dimethylbutane; 2,3 VHI4= 2,3-Dimethylbutane; 2 MC5= 2-methylpentan; 3MC5= 3-methylpentan; CC5= cyclopentane; MCC5= Methylcyclopentane; CC6= cyclohexane.

1. Catalyst for reducing the benzene content in gasoline fractions for the isomerization of hydrocarbons containing media on the basis of aluminum oxide, the metal of group VIII supported on a carrier, and halogen, characterized in that it contains 4 to 15 wt.% at least one of halogen and 0.05 - 10 wt. % of at least one metal of group VIII supported on a carrier, which practically consists of ETA-alumina and gamma-alumina, and the content of this alumina is 85 to 95 wt.% in relation to the media, the rest up to 100 wt.% is gamma-alumina.

2. The catalyst p. 1, characterized in that on one of the p. 1 and 2, characterized in that the metal of group VIII selected from the group consisting of platinum, palladium and Nickel.

4. The catalyst according to any one of paragraphs.1 to 3, characterized in that the aluminum oxide has a specific surface area of 400 - 600 m2/g and a pore volume of 0.3 - 0.5 cm3/,

5. The catalyst according to any one of paragraphs.1 to 4, characterized in that the gamma alumina has a specific surface area of 150 to 300 m2/g and a pore volume of 0.4 - 0.8 cm3/,

6. The catalyst according to any one of paragraphs.1 to 5, characterized in that the halogen content is 6 to 15%.

7. The catalyst according to one of paragraphs.1 - 6, characterized in that the halogen is chlorine.

8. The catalyst according to one of paragraphs.1 to 7, characterized in that it is used in the method of reducing benzene in gasoline fractions and isomerization of paraffins.

9. The method of reducing the content of benzene in gasoline fractions in the presence of a catalyst comprising isomerization of hydrocarbons, characterized in that the use of the catalyst containing the medium consisting practically of this-alumina and gamma-alumina with the content of this-alumina 85 - 95%, the rest is gamma-alumina, at least one metal of group VIII in the amount of 0.05 - 10%, applied to the nose is stoaway of the boot, contains 40 to 80 wt.% paraffins, 0.5 to 7 wt.% cyclic hydrocarbons and 6 - 45 wt.% aromatics and having a maximum temperature distillation 70 - 90oWith, and from fraction C5- C6with a paraffin content greater than 90 wt.%, cyclic hydrocarbons below 10 wt.% and benzene below 1.5 wt.%.

10. The method according to p. 9, characterized in that the isomerization is conducted under the following operating conditions: a temperature of 100 - 300oC, the partial pressure of hydrogen between atmospheric pressure and 70 bar, the volumetric feed rate is between 0.2 and 10 l per 1 l of catalyst in 1 h, the molar ratio hydrogen/feedstock at the inlet of the reactor is such that the ratio of hydrogen/feedstock into an output stream above 0.06, and introducing the raw material compound of chlorine in the amount of 50 to 5000 million-1.

11. The method according to p. 9 or 10, characterized in that the fraction C5- C6is the fraction of direct distillation.

12. The method according to PP.9 to 11, characterized in that the mixture contains 10 to 90 wt.% fraction C5- C6.

 

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