CS277124B6 - Process for preparing oxy component of motor petrols - Google Patents

Abstract

There is described the production of an automobile oxy-fuel component containing, in addition to light gasoline hydrocarbons, a target. especially alkyl methyl ethers; amylmethylether. The production consists of reacting isoolefins with quaternary carbon with a methanel containing optionally other oxydic compounds and conducting the product free of methanol or resin which is detrimental to the gasoline, the combination of the hydrogenation catalyst and the acidic catalyst in the presence of hydrogen. Moreover, an increase in the yield of the oxides is achieved in part

Description

The present invention relates to the production of the oxo component of motor gasolines from light olefinic gasoline fractions by reaction with methanol over an acid catalyst, whereby a high yield of target amyl methyl ether is obtained using technical grade methanol and the product is free of resins.

The latest trends in the formulation of gasoline for petrol engines in terms of optimal ecology and economy include the addition of oxygen compounds, especially alcohols and even more often ethers. The reformulated gasoline should contain up to 2.7% by weight of oxygen bound in organic compounds. The presence of oxygenated compounds ensures better combustion of hydrocarbon components and carbon monoxide. In addition, the combustion temperature is regulated so that less nitrogen oxides are produced. Oxygenated organic compounds have predominantly high octane numbers, although as measured by research rather than motor. They therefore serve as anti-knock compounds and make it possible to reduce the concentration of aromatics, from which harmful products and polyaromatics with carcinogenic effects are formed.

The main useful oxygen compounds are low-boiling alcohols, methanol and ethanol, as well as ethers, methyl tert. butyl ether (MTBE) and of the homologues in particular the target, amyl methyl ether (TAME). The preparations of ethers are based on so-called reactive isoolefinic compounds containing a quaternary carbon with a double bond. The simplest is isobutene for MTBE and 2-methylbutenes for TAME. These olefins are part of the light gasolines produced by pyrolysis or catalytic cracking of petroleum fractions, and the most common method for producing ethers with a target, alkyl is the edition of methanol (or ethanol) to a reactive isoolefin. While thermodynamic and kinetic conditions are very favorable for MTBE synthesis and 95% isoolefin conversion is obtained at low temperatures around 70 ° C in the presence of acid catalysts, with increasing molecular weight, i.e. carbon number, the thermodynamic equilibrium shifts rapidly towards the starting mixture. In addition, the higher olefinic fractions contain diene residues even after their selective hydrogenation. Dienes are precursors of resins which are undesirable in motor gasoline because they clog the intake tract of engines, especially carburetors, injectors and valve seats. There are a number of technological modifications to achieve the economical production of TAME. One of them, in which a modified raw material, a lower quality methanol, a combination of hydrogenation and addition, is used, is described by the present invention.

The oxo component of motor gasoline is produced from the light olefinic gasoline fraction and from methanol. The process is characterized in that a mixture of C ₅ to C ₇ hydrocarbons containing reactive isoolefins with quaternary carbon and diene residues after selective hydrogenation is combined with methanol optionally containing up to 2% by weight of water and up to 2% by weight of other oxygenates, especially dimethyl ether in a ratio of 0.75 to 1.25 moles of methanol per mole of reactive isoolefins, the mixture is heated with 0.5 to 5 m ^{3 of} hydrogen gas / m ^{3 of} raw material to 60 to 90 ° C under a pressure of 0.5 to 2.0 MPa and is fed to two successive stages, in which two kinds of catalysts are placed successively, namely in the first porous cation exchange resin in the H-form containing 0.2 to 0.4% by weight of palladium and in the second porous cation exchange resin in the H-form. form in proportion

1: 3 to 3: 1, at a volume rate of 0.2 to 4.0 volumes of liquid per volume of catalysts per hour, the product from the second stage is mixed in a volume ratio of 0.05 to 0 volumes after cooling to a temperature of 10 to 30 ° C. With water or aqueous methanol diluted in a volume ratio of 3: 1 to 1: 3, and after phase separation, the methanol separated from the aqueous phase by distillation is returned to the reaction. The mixture of C ₅ to C ₇ -hydrocarbons preferably originates from pyrolysis gasoline and contains only C ₅ -hydrocarbons, optionally additional C 8 -hydrocarbons boiling before benzene, or the mixture originates from catalytic cracking gasoline and boils up to 70 to 90 ° C. Technical methanol can advantageously be derived from the decomposition of dimethyl phthalate by ethylene glycol and contains, in addition to dimethyl ether, other oxidic organic compounds, vol. ethers, acetals and esters. Preferably hydrogen gas comes from a catalytic reformer and comprises 65-90% by weight, in addition to hydrogen Ci - C ₄ -alkane.

A number of new modifications can be made against the known technological processes, the most important of which are the following: the pyrolysis feedstock additionally contains a hexane fraction boiling before benzene, which expands the base and in addition some of the Cg isomeric isoolefins may be present. The methanol used, although in pure form has a cost of about 0.75 petrol, can also contain water and organic impurities, as they occur, for example, in the decomposition of methyl esters of organic acids, which is otherwise a product requiring costly treatments. The amount of hydrogen is chosen so that it is stoichiometrically sufficient to saturate the dienes and dissolve in the feedstock, which is in the liquid phase even under the reaction due to pressure. Reforming hydrogen, which is economically advantageous, is sufficient to prevent the formation of resins and to prevent coking of the palladium catalyst.

Unreacted methanol remains in the etherification product, which would pass into the gasoline and be washed for the most part with mixed water. This is economically disadvantageous. Therefore, recirculation of unreacted methanol is included.

To remove the dienes, the location of the conventional catalyst containing Pd on alumina is chosen to be the cation exchange resin in H-form, to which palladium in the form of cations is added and reduced to metallic Pd. The same particle shape is also preferred.

The example below shows all the features of the new method.

Example

From the commercially produced pyrolysis gasoline, a C ₅ - C 8 -fraction was prepared according to the invention, the composition of which is given in Table 1. It contains 12.5% of C 8 -hydrocarbons boiling before benzene and has the fuel qualities given in Table 2.

In the experimental apparatus, it was mixed with technical grade methanol obtained as a by-product in the reaction of ethylene glycol with dimethyl phthalate. Its characteristics are given in Table 3. The mixture was introduced into a system of two catalysts, Pd-cation exchange resin and H-form cation exchange resin, arranged in series.

The ratio of both was 1: 1.

1.5

1.0

1.0

1.0

The reaction conditions were as follows:

pressure, MPa

LHSV, h ” ¹ volume of hydrogen / volume mixtures of mol. CH ₃ OH / isoolefin ratio temperature, ° C

The reaction product had the composition and qualities given in Table 4. In this table, the product is also obtained only on the acid catalyst. There is a noticeable difference in resin content and color.

The reaction product was then washed by the addition of 7.5% v / v water and the change in quality was assessed as shown in Table 5.

The methanol water was distilled off and the methanol and hydrocarbon residues were returned to production.

Table 1

Typical composition of pyrolysis C ₅ -C 8 -fraction (% by weight)

^C 4 0.4 isopentane 9.8 pentene-1 0.8 2-methylbutene-1 3.1 n-pentane. 15.7 trans-pentene-2 6.8 cis-pentene-2 2.3 2-methylbutene-2 17.9 cyclopentene 5.6 cyclopentane 25.1 ^C 6 12.5

Table 2

Fuel analyzes of pyrolysis C _{5 -C 8 -fraction}

Density / 20 ° C, kg / m ³ 680 Distillation curve, ° C: z. d. 35 10% vol. 40 50% vol. 41 90% vol. 48 k. d., · /% vol. 63/98 Vapor pressure, kPa 105 Bromine number, g Br / 100 g 70.5 Resin, mg / 100 ml 1 OČVM 93.7 OČMM 78.5 OČVM + 0.15 g Pb / 1 (TEO) 97.6 OČMM + 0.15 g Pb / 1 (TEO) 83.3

CS 277124 B6 4

Table 3

Characteristics of technical methanol

Component Content,% wt. methanol 97.9 water 1.4 esters 0.4 aldehydes 0.2 ethylene glycol 0.1

Table 4

Characteristics of etherification products

Catalytic charge Acid catalyst Bifunctional + acid cat. Product composition, % by weight: ch ₃ oh. 4.1 4.2 TAME. 15.4 15.3 2-methylbutene-1 1.0 1.0 2-methylbutene-2 9.4 9.5 others C ₅ 58.5 58.2 ^C 6 11.6 11.8 Product quality: no. number, g Br / 100 g 51.2 50.0 dien. number, g / 100 g 0.54 0.08 color (ASTM D 1500) 0.75 - 1.0 0 - 0.25 OČVM 97.1 97.0 OČMM 82.3 82.6

Table 5

Influence of methanol removal on etherification product quality

Sample Etherification product Etherification product after methanol extraction Composition,% wt. ch ₃ oh 4.2 0 TAME 15.3 16.0 other 80.5 84.0. Anti-knock character. OČVM 97.0 95.8 OČMM 82.6 82.0 sensitivity (VM-MM) 14.4 13.8

Claims (4)

PATENT CLAIMS A process for the preparation of the oxo component of motor gasoline from a light olefinic gasoline fraction containing reactive isoolefins with quaternary carbon and methanol, characterized in that the mixture C ₅ . to _C7 -hydrocarbons, which also contain diene residues after selective hydrogenation, are combined with methanol, optionally containing in addition up to 2% by weight of water and up to 2% by weight, of other oxygenates, in particular dimethyl ether, in a ratio of 0.75 to 1.25 mol. to reactive isoolefins, the mixture is heated with 0.5 to 5 m ^{3 of} hydrogen gas / m ³ to 60 to 90 ° C under a pressure of 0.5 to 2.0 MPa and passed to two successive reaction stages in which two types of catalysts are placed, namely in the first stage porous cation exchange resin in H-form containing 0.2 to 0.4% by weight of palladium and in the second stage porous cation exchange resin in H-form in a ratio of 1: 3 to 3: 1, at volume at a rate of 0.2 to 4.0 volumes of liquid per volume of catalysts per hour, the product from the second reactor after cooling to 10 to 30 ° C is mixed in a volume ratio of 0.05 to 0.15 with water or aqueous methanol diluted in volume ratio 3: 1 to 1: 3 and after phase separation, the methanol distilled off from the aqueous phase is returned to the reaction. Process according to Claim 1, characterized in that the mixture C ₅ to C ₇ -hydrocarbons originate from pyrolysis gasoline and contain only C ₅ -hydrocarbons, optionally additional C ₆ -hydrocarbons boiling before benzene, or the mixture originates from gasoline catalytic cracking and boils up to 70 to 90 ° C. Process according to Claims 1 and 2, characterized in that the methanol originates from the decomposition of dimethyl phthalate by ethylene glycol and contains, in addition to dimethyl ether, further oxidic organic compounds, vol. ethers, acetals and esters. Process according to Claims 1 to 3, characterized in that the hydrogen gas originates from the catalytic reforming and contains 65 to 90% by weight of hydrogen in addition to C ₁ -C 4 hydrocarbons.