DD243924B1 - METHOD FOR THE HF-CATALYZED ALKYLATION OF BUTENS WITH ISOBUTANI-ISOPENTANE MIXTURES - Google Patents

Description

Characteristic of the known technical solutions

It is known that isopentane or isopentane fractions have very good fuel properties and are therefore used in relatively large quantities for the production of carburettor fuels.

However, the use of isopentane in the HF-catalyzed alkylation of butenes (L. Schmerling "Alkylation of Saturated Hydrocarbons" in G.A.OIah "Friedel-Crafts and related reactions, Vol. 11, London 1964, pp. 1075-1131 and also US Pat

L. I.Vstavskaja u.a. Chim. Technol. Topi. Masel 18 [2], [1973], p.4-6) to alkylate petrol. Such a technical solution is of interest when it comes to convert butene excesses, as they occur in certain locations, with insufficient Isobutanverfügbarkeit in gasoline hydrocarbons. For this purpose, it is also known that isopentane is used only with isobutane in the mixture, since the sole Isoperitaneinsatz leads to extremely heavy and thus highly quality-reduced alkylates. (RM Kennedy "Catalytic Alkylation of Paraffins with olefins" in "Catalysis", Vol. Vl, London 1958, pp 1-41). However, the alkylation with isopentane-isobutane mixtures brings the disadvantages described to a considerable extent. so that isopentane is used only to a very limited extent as isoalkane in the HF-catalyzed alkylation of butene mixtures.

It is also known that in the case of the sulfuric acid alkylation by aminic additives, an improvement in the octane number or a reduction in acid tar formation can be achieved.

However, the procedure set forth in U.S. Patent No. 3,324,196 for the amine concentration to be set at 0.0005-0.3 mass% would not result in the desired micellar catalysis upon HF alkylation. The influence of the reaction which can be achieved in this concentration range for the sulfuric acid alkylation can be attributed to pure phase transfer phenomena.

This has the disadvantage that higher concentrations up to the critical micelle concentration (c.t.) lead to considerable disruption of the system by formation of stable emulsions and sludges (compare GM Kramer, ACS Symp. Ser. [Ind. Lab. 55 [1977], 1-26) is encountered by adding emulsionsbrechender additives, such as industrially unavailable adamantane derivatives, as can be seen from US Pat. Nos. 4,357,481, 4,357,482 and 4,560,825.

Object of the invention

The aim of the invention is an economical process for the HF-catalyzed alkylation of butenes with isobutane-isopentane mixtures, which makes it possible to produce high-quality alkylates having a boiling point customary for pure isobutane-butene alkylates.

Explanation of the essence of the invention

Refineries operating thermally or catalytically active fission processes produce more or less large amounts of but rich C ₄ fractions, which must be further processed with the highest possible economic effect. Frequently such fractions are used as feedstocks in alkylation processes and used for the production of fuel components. Depending on the processing and product structure, some sites may lack the isobutane required for butene conversion. In principle, such an isobutane deficiency can be compensated proportionally by isopentane. However, the resulting from isopentane-isobutane mixtures butene alkylates are sometimes provided with significant quality defects that allow their use as fuel blending components only conditionally. A serious disadvantage is the strongly shifted to higher boiling ends Siedelage so that the required after fuel TGL boiling fraction of 180 ⁰ C of at least 90VoI .-% can not be met or only if very low isopentane shares are used.

In order to eliminate all or part of these shortcomings of known processes, it is an object of the present invention to develop a process which makes it possible to influence the boiling position of alkylates which are formed in the reaction of butene fractions with isobutane-isopentane mixtures, that at least 90VoI .-% to 180 ⁰ C boil.

According to the invention, this object is achieved in that in the HF-catalyzed alkylation of butenes with isobutane-isopentane mixtures in the presence of liquid, substantially anhydrous hydrogen fluoride at a temperature of 10-40 ° C, a pressure of 1-2MPa, a molar isoalkane Butene ratio of 10-20, an acid to hydrocarbon volume ratio of 1-2, an acid strength of 85-90 wt% titratable hydrogen fluoride and an acid-hydrocarbon contact time of 2-10 min of the acid phase in the reaction zone either primary, long-chain n-alkylamines of the general formula R-NHj having alkyl radicals R of Ci ₄ -C ₂₄ , preferably Ci ₆ -Ci ₈ , individually or in a mixture, or unsymmetrical, long-chain both secondary and tertiary n-alkylamines of the type R1 NH-R2 or Ri-N- (R ₂ J ₂ with alkyl radicals Ri of C ₁₄ -C ₂₄ , preferably Ci ₈ -C ₈ individually or in a mixture and radicals R ₂ in the form of methyl and / or ethyl groups or unsymmetrical, long-chain, qua Rary ammonium halides corresponding to the formula [Ri-N- (R ₂ b] X ^e with alkyl radicals Ri in the C-number range Ci ₄ -C ₂₀ , preferably Ci ₆ -C ₈ , individually or in a mixture and radicals R ₂ in the form of methyl and / or ethyl groups are added in such an amount that adjust levels of 70-100 mmol amine or ammonium salt per kg of hydrogen fluoride.

embodiments

The process according to the invention will be explained in more detail by the examples listed below in comparison with the conventional processes.

For example, attempts for the alkylation of butenes with isobutane isopentane mixtures in the presence of hydrogen fluoride, an apparatus was used that allows working in the similar technical alkylation process parameters (reaction temperature 20-25 ⁰ C; Morales isoalkane-butene ratio 10-15 Acid hydrocarbon volume ratio 2).

The apparatus consists of a vertically arranged heat exchanger type cylindrical reactor (diameter 28.5 mm, height 110mm) with side overflow connected to an HF leveling vessel via a floor mounted piping.

The confluence of this line in the bottom of the reactor is designed cone-shaped. A capillary tube with a diameter of 2.5 mm, which is passed through the interior of the HF line, also flows through which the hydrocarbon mixture is metered by means of a pump (metering rate 8-8.5 g / min). The ejector effect facilitates the leveling of the hydrogen fluoride between the vessel level and the reactor. The acid level in the reactor can be varied with the help of the level vessel, its maximum height is determined by the overflow at the reactor. About the latter, the alkylate and z.T. Hydrogen fluoride in a vertically arranged, cylindrical Settier, in which the phase separation takes place. With the help of a suitable valve system then the hydrogen fluoride (detecting the phase boundary by conductivity measurement) can get into a receptacle and be returned from there by a pressure pulse by means of nitrogen in the level vessel, while the hydrocarbon phase is discharged for processing from the settler

 The doping of the acid phase with the amine additives takes place in the level vessel. The example experiments were carried out with a feed product whose composition is contained in Table 1.

Table 1: Composition of the starting material (% by mass)

Feedstock A Feedstock 8

component 34.4 component 33.1 (Example 1-3) 10.0 (Example 4-5) 9.8 isobutane 4.3 isobutane 4.1 n-butane 14.1 n-butane 14.8 ! butenes 37.2 ! butenes 38.2 isopentane isopentane n-pentane n-pentane

Example 1 (known method)

125 g of the feed product mixture (see Table 1) were pumped from a cooled storage vessel into the reactor by means of a metering pump (metering rate 8-8.5 g / min), the cooling of the reactor being regulated so that a temperature of about 20 ⁰ C in the reactor set. An acid-to-hydrocarbon volume ratio of 2: 1 was present. After the phase separation in the settler (total residence time 5-8 min), the hydrocarbon phase was worked up without distillation and analyzed by gas chromatography (see Table 2).

Example 2 (method according to the invention)

125 g of the starting material mixture (cf., Table 1) were reacted analogously to Example 1 and the reaction product formed was likewise worked up, but the hydrogen fluoride phase had been added to 70 mmol of Quats I per kg of hydrogen fluoride. Quats I represents a mixture of the two quaternary ammonium salts In-Ci ₆ H ₃₃ -N- (CH ₃ J ₃ ] СІ ^Ѳ and [n-Ci ₈ H ₃₇ -N- (CH ₃ ) ₃ ] СІ ^Ѳ . The resulting alkylate was characterized by the data listed in Table 2.

Example 3 (method according to the invention)

125 g of the starting material mixture (cf., Table 1) were reacted analogously to Example 1 and the reaction product mixture formed was likewise worked up, but 70 mmol of rofamine TD per kg of hydrogen fluoride had been added to the hydrogen fluoride phase. Rofamin TD is a technical product consisting of 90% of a mixture of the primary amines Ci ₆ H ₃₃ -NH ₂ to Ci ₈ H ₃₇ -NH ₂ . The resulting alkylate was characterized by the data listed in Table 2.

Example 4 (known method)

125 g of the starting material mixture B (see Table 1) were reacted analogously to Example 1 and the reaction product formed was likewise worked up and analyzed by gas chromatography (see Table 2).

Example 5

125 g of the starting material mixture B (cf., Table 1) were reacted analogously to Example 1 and the reaction product formed was likewise worked up, but 20 mol of RofaminTD per kg of hydrogen fluoride were added to the hydrogen fluoride phase. The resulting alkylate is characterized by the data listed in Table 2. For explanation, it should be noted that 70 mmol RofaminTD / kg HF correspond to a content of about 1.8 wt .-%.

Table 2: Results of the alkylate studies

1 2 such tests 4 5 3.5 » 18.7 » 3 4.1 * 3.9 Isoptentane (% by mass) 4.6 5.6 21.9 * 5.0 4.8 2iC _e (% by mass) 3.9 3.2 6.2 3.8 3.7 XiC ₇ (% by wt) 65.9 47.8 2.9 65.0 65.5 2iC _e (% by mass) 17.8 19.5 44.4 18.2 18.0 2iC ₉ (% by wt) 4.3 5.2 17.7 3.9 4.1 2> C ₉ (% by wt) 6.9 100 ° C 12.0 27.5 11.0 12.0 sied. Share (Vol .-%) 31.0 Up to 180 ⁰ C 82.3 93.1 83.0 82.0 sied. Share (Vol .-%) 79.1 84.8 95.2 79.3 79.3 Frontoctance number (FOZ) 82.5 87.0 87.5 83.0 82.8 Research octane number (RON) 89.0

* after deducting the amounts of isopentane used

The results summarized in Table 2 show by using the inventive solution (Examples 2 and

3) achieved effects over the procedure according to known methods (Example 1).

By using the additives Quats I and RofaminTD in an amount of 70mmol / kg of hydrogen fluoride are the important parameters for gasoline blending components, such. B. boiling components to 100 ⁰ C and 180 ⁰ C, frontoctance and Researchoktanzahl significantly improved.

Noteworthy in this context is above all the increase in the proportion boiling to 18O ⁰ C to> 90%.

This makes it possible to produce alkylates even when using iC ₅ -rich butene fractions, which meet despite their high proportion of iCg the requirements placed on gasoline with respect to the boiling behavior.

Completely surprising is the significant RON increase when using the method according to the invention of more than 5 OZ units.

Claims (1)

A process for the HF-catalyzed alkylation of butenes with isobutane isopentane mixtures in the presence of liquid, substantially anhydrous hydrogen fluoride at a temperature of 10-40 ⁰ C, a pressure of 1-2MPa, an acid-hydrocarbon volume ratio of 1-2, an acid strength of 85-90 wt% titratable hydrofluoric acid and an acid-hydrocarbon contact time of 2-10 min, wherein at a molar isoalkane-butene ratio of 10-20 of the acid phase in the reaction zone either a mixture of the primary n-alkylamines Cj ₆ H33NH ₂ and C ₁₈ H ₃₇ NH ₂ or the quaternary ammonium salts In-C ₁₆ H ₃₃ N (CHa) _3] ^СІ Ѳ H ₃₇ N (CH _{3) 3]} Cl ⁹ is supplied to [nC _18, characterized in that that the supply takes place in such an amount that sets a content of 70mmol / kg of hydrogen fluoride. Field of application of the invention The invention relates to a process for the HF-catalyzed alkylation of butenes with isobutane-isopentane mixtures especially for the utilization of butane excesses to high-octane alkylates using specific catalyst additives.