FI111463B - Process for producing an oxygenated gasoline component and a gasoline component thereof - Google Patents

Abstract

The invention relates to formulated gasoline. Specifically oxygenated gasoline components and gasoline oxygenates are concerned. More specifically the invention concerns a method of producing a high-octane oxygenated gasoline component and a gasoline component thereof and use of 2-ethxy-2,4,4-trimethyl pentane as a gasoline component. The overall process for producing the gasoline component comprises three steps: isomerisation of n-butane to isobutane and dehydrogenation of isobutane to isobutene, dimerisation of isobutene to a mixture of isooctenes and etherification of isooctenes with ethanol.

Description

111463

A process for the preparation of an oxygenated gasoline component and a gasoline component

The present invention relates to a gasoline composition which. known as the Reformed 5 gasoline. The invention relates to oxygenated gasoline components and gasoline oxygenates. In particular, the invention relates to a process for the preparation of a high octane oxygenated gasoline component and a gasoline component thereof.

Oxygenates are oxygen-containing organic compounds added to gasoline 10 to improve the combustion reaction of gasoline in the engine and, consequently, to reduce carbon monoxide and hydrocarbon emissions. Commonly used oxygenates are alcohols (Cx-O-H) and ethers (Cy-O-Cz) having from 1 to 6 carbons. Methyl tert-butyl ether (MTBE) is the most commonly used oxygenate in motor gasoline. However, new MTBE-related environmental problems have emerged. Because MTBE is highly soluble in 15 water, it has been found to cause bad odor and taste in groundwater. As a result, the use of MTBE in gasoline has been banned in California since early 2003.

However, even after the ban on MTBE, reformed gasoline should still contain 2% oxygen. It is therefore evident that new MTBE-free high octane oxygenated petrol compositions are needed to meet the air quality regulations for gasoline and to meet the requirements of existing car engines. Proposed suitable MTBE-substituting chemicals include alcohols and ethers such as ethanol, methanol, tert-butanol and other tertiary alkyl ethers. A very realistic alternative is ethanol with good octane numbers. It can be predicted that ethanol use as a component of motor gasoline will increase in the near future. However, ethanol increases the vapor pressure of gasoline and is water soluble.

Finnish Patent Application 20001679 relates to an oxygenate containing gasoline and a process for the preparation of a suitable oxygenate for gasoline, namely 2,4,4-trimethyl-2-pentanol. According to the application, the total oxygen content of gasoline is 2 to 20% by volume and the oxygenate consists of one or more of the following compounds: 2,4,4-trimethyl-2-pentanol, 2,4,4-trimethyl-2-methoxypentane and ditert-2 111463 butyl ether. Its petrol has a research octane rating (RON) and an engine octane rating (MON) of more than 90 and 80 respectively.

The present invention relates to a process for the preparation of an oxygenated MTBE-free gasoline component and a gasoline component product. The invention is based on the idea that ethanol and / or heavier ethanol ethers are used as oxygenates in gasoline.

Furthermore, the invention is based on the idea of converting at least a portion of the ethanol, which may remain as the oxygenate in the final gasoline, to water-insoluble ethers. More water-insoluble heavier ethers can be obtained by reacting iso-oc-10-teenes, especially a mixture consisting essentially of 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene, with ethanol.

Suitable starting materials for the new gasoline component prepared in accordance with the present invention are field butanes and ethanol. The overall process has three steps: - isomerization of n-butane to isobutane and dehydrogenation of isobutane to isobutene - dimerization of isobutene to a mixture of iso-octenes - etherification of iso-octenes with ethanol.

The recovered mixture is suitable as a gasoline component, either alone or mixed with the product recovered from the dimer 20 unit. A notable advantageous feature of the process is that removal of the ethanol remaining in the etherification product is unnecessary. Excess ethanol can be used in the etherification step to increase conversion to ether.

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In the first step, n-butane is isomerized with a known isomerization catalyst known as isobutane, such as platinum supported on alumina or zeolites. At least four dehydrogenation processes are available for isobutane to isobutene dehydrogenation:

Catofin, Oleflex, Phillips and Snamprogetti-Yarsynthesisin. The catalysts used are based on either supported chromium or supported precious metals. Another difference between the processes is the manner in which the heat required for the very endothermic dehydrogenation reaction is supplied.

30

In the next step, isobutene is converted to iso-octenes with an ion exchange resin catalyst. The reaction is typically carried out under pressure in a liquid phase. A small amount of oxygenate such as methanol, tert-butyl alcohol (TBA) or MTBE is added to improve the dimer selectivity of the reaction. The iso-octene product consists essentially of two isomers, namely 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene, each having a carbon atom attached to a methyl group and a double bond. This type of carbon has been shown to be reactive in the etherification reaction.

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In the final step, the iso-octenes react with ethanol to form the ether, 2-ethoxy-2,4,4-trimethylpentane. This reaction is also carried out in the liquid phase using a strong cation exchange resin as a catalyst. Other acid catalysts may also be used. The etherification temperature is typically below 100 ° C because the thermodynamic equilibrium for the exothermic reaction decreases with increasing temperature. The equilibrium conversion can be improved by using excess ethanol in the reaction mixture.

The reaction product contains unreacted iso-octenes, unreacted ethanol and ether formed and can be used directly as a blend component of gasoline without further separation steps. The resulting 2-ethoxy-2,4,4-trimethylpentane has excellent properties as a gasoline component. It is almost insoluble in water, has a low vapor pressure and has high octane numbers.

If ethanol is not desired in gasoline, the unreacted ethanol may be separated from the reaction product 20 and the remaining mixture may be used. In that case, the oxygenate-containing mixture is completely insoluble in water.

The present invention provides significant advantages. The liquid blend produced by the process of the present invention is an excellent gasoline component having a high octane rating and low vapor pressure compared to a blend using only pure ethanol as oxygenate. The olefin content of the gasoline component decreases and the octane number increases as a result of etherification. The ethers used have a higher boiling point; · 'than the MTBE boiling point. In addition, the solubility of the ethers used in water is decisively less than that of MTBE. A process for the manufacture of gasoline components is preferred. Moderately low conversion of ether can be improved by using excess ethanol and still have ethanol remaining in the final gasoline component.

Thus, the expensive ethanol separation step from the product is avoided. For example, when producing MTBE, the overall process involves the step of removing alcohol from the product.

111463

Ethanol is a preferred process raw material because it can be produced from biomass and is therefore a renewable compound.

If 2-methoxy-2,4,4-trimethylpentane was produced in accordance with the present invention, the use of excess methanol for etherification would result in a step that would require the separation of methanol from the final product. In addition, said methanol ether had a lower water solubility (about 100 mg / kg), a boiling point (149 ° C) and octane numbers (RON 110, MON 98) than those of ethanol ether.

10

It is known that the etherification reactions of the heaviest ethers are clearly slower than those of lighter ethers such as MTBE or TAME. Therefore, it is particularly advantageous to use excess alcohol in the etherification process to produce 2-ethoxy-2,4,4-trimethylpethane.

15

In the context of the present invention, "oxygenated gasoline component" means a liquid mixture of hydrocarbons and one or more oxygen-containing organic compounds which improve the combustion reactions of gasoline and / or reduce carbon monoxide and / or hydrocarbon emissions from cars.

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Figure 1 shows a flow chart of a process according to the present invention. Stream 1 consists essentially of isobutene. Stream 2 is the dimerized product stream of stream 1, i.e.. main: · in the case of diisobutene. Stream 3 contains ethanol and Stream 4 is the reaction product mixture of the etherification unit 6. The product contains ether, ethanol and diisobutene. Optionally, the product of etherification 25 in unit 7 is mixed with base gasoline, such as non-oxygenated gasoline 95. Optionally, a portion of the dimerized product of unit 5 is separated into another stream and mixed with the etherified product of unit 6 in unit 7.

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According to a preferred embodiment of the present invention, the process for preparing the oxygenated gasoline comprises the following steps in the indicated (order: - supplying n-butane to the isomerization unit, - recovering the isomerized reaction product consisting essentially of isobutane, 5111463 - recovering the isomerization unit, the reaction product consisting essentially of the iso-octene isomers, - feeding the reaction product recovered from the isomerization unit and ethanol into the etherification unit, 5 - etherifying in the liquid phase in the presence of an acid catalyst, and - recovering the reaction product.

N-butane is fed to the isomerization as a feed consisting essentially of n-butane.

The process of the preferred embodiment may comprise the step of mixing the product recovered in the etherification step with the product recovered from the dimerization unit.

In addition, the process may, if necessary, comprise the step of separating the ethanol from the etherified product before mixing it with the final gasoline product.

In order to accelerate the etherification process and improve its conversion, the molar ratio of ethanol to iso-octenes fed to the etherification unit preferably ranges from 1 to 8.

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The etherification is preferably carried out at a temperature below 200 ° C, especially at a temperature between 70 and 90 ° C.

I · t

The preferred ether for the etherification is 2-ethoxy-2,4,4-trimethylpentane. Thus, the preferred feed to the 25 etherification units contains a hydrocarbon feed consisting essentially of 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene. Further, to avoid unnecessary isomerization during the etherification, the molar ratio of 2,4,4-trimethyl-1-pentene to 2,4,4-trimethyl-2-pentene in the hydrocarbon mixture fed to the etherification unit corresponds to the thermodynamic equilibrium of the mixture.

30

The oxygenated gasoline component produced in accordance with the present invention typically consists of 2-ethoxy-2,4,4-trimethylpentane in an amount ranging from 2 to 20% by weight, methyl terbutyl ether in an amount of less than 1% by weight, ethanol in an amount of 6 to 11163% in octenes in an amount ranging from 15 to 85% by weight.

The oxygenated gasoline component can be blended with any type of gasoline, typically unleaded gasoline such as the 95 and 98 types. i

According to the present invention, 2-ethoxy-2,4,4-trimethylpentane is a suitable oxygenate in reformed gasoline. When the ether is used as the oxygenate in gasoline, the amount of ether is less than 20% by volume, preferably 1-5% by volume. The ether can be blended with unleaded petrol, such as the 95 and 98 types.

Example 1

The etherification process of the present invention forms 2-ethoxy-2,4,4-15 trimethylpentane. The properties of ether and MTBE are compared by measuring octane numbers and water solubility. Oxygenates are mixed with typical gasoline and RON and MON values are determined. The following compares the properties of 2-ethoxy-2,4,4-trimethylpentane and MTBE (Table 1).

20 Table 1

2-Ethoxy-2,4,4-trimethylpentane MTBE

mixing RON 115 ... 116 117 mixing MON 100 ... 101 100 solubility in water (mg / kg) 60 43000 purity (%) 97> 95 density (kg / m3) 794 745 boiling point (° C) 160 55

It can be clearly seen that 2-ethoxy-2,4,4-trimethylpentane has very high octane numbers and is almost completely insoluble in water.

25 7 111463!

Calculated example

Diisobutene was etherified with ethanol in an etherification unit. The molar ratio of ethanol in the etherification unit to diisobutene (DIB) was 4, i.e.. the feed had a DIB content of 37.8% by weight and an ethanol content (EtOH) of 62.2% by weight.

At 50 ° C, the DIB conversion was 9.0% At 70 ° C, the DIB conversion was 5.5% at 90 ° C, the DIB conversion was 3.9%.

The product composition (calculated with a 10% conversion) was roughly DIB 34.1% by weight, EtOH 60.6% by weight and ether 5.3% by weight at 50 ° C etherification temperature. The oxygen content of the mixture was 21.6% by weight.

By reactive distillation, the conversion of DIB could be increased to 30%, the composition of the product would be: DIB 26.5% by weight, EtOH 57.5% by weight and ether 16.0% by weight.

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Claims (10)

Oxygenated gasoline component, characterized in that it comprises - 2-ethoxy-2,4,4-trimethylpentane in an amount ranging from 2 to 20% by weight, - methyl tert-butyl ether in an amount of less than 1% by weight, - ethanol in an amount ranging from from 1 to 65% by weight, and - iso-octenes in an amount ranging from 15 to 85% by weight. 2. Förfarande för framställning av en oxygenerad petrol component, transducer 10 av att det omfattar feljande steg: - n-butan tillförs en isomerizationenhet, - den isomerization product, som bestär väsentligt av isobutanen, tas tillvaraen, - den frän isvarerenen - reactants, 15. reactorsproducten, som bestär tiredligt av isomerer av iso-octen, tas tillvara, - den frän isomereriseringsenheten tillvaratagna reactionsprodukten och ethanol tillförs en företringsenhet, - företringen utförs i vätskefas i nvarvaro av syrakatalvaraator, angiven ordning. A process for the preparation of an oxygenated gasoline component, comprising the steps of: - feeding n-butane to an isomerization unit, - recovering an isomerized product consisting essentially of isobutane, - feeding a reaction mixture recovered from the isomerization unit to a dimerization unit, - isomers of the octene, - feeding the reaction product recovered from the isomerization unit and ethanol to the etherification unit, - carrying out the etherification in the liquid phase in the presence of an acid catalyst, and - recovering the reaction product, in the order indicated. 3. Förfarande enligt patentkrav 2, N e t e c t a n d e r t e r t e r e d e d e d e d e d e d e d i d e d 25. en del av det frän dimeriseringsenheten tillvaratagna reaction product flöder denen separant fren företringsstegenen blandas delenen delanden delanden delanden delanden avant. 30 4. Förfarande enligt patentkrav 2 och 3, k n e t e c n a t av att-n-butan leds in isomerization ring flask, som väsentligt bestär av n-butan. 11 111463 The process of claim 2, further comprising the steps of separating a portion of the reaction product stream recovered from the dimerization unit, and - mixing the recovered etherification step reaction product from the dimerized unit recovered product portion. Process according to claims 2 and 3, characterized in that n-butane 30 is introduced into the isomerization unit in the form of a hydrocarbon feed consisting essentially of n-butane. 111463 5. Förfarande enligt patentkrav 2 och 3, kangnetecnat av att det vidare omfattar etig, in ethanol separator frän den företrade produce in den blandas petrol slutliga. t, 5 6. Förfarande enligt patentkrav 2, a n d t e c e a n d e d e c t e d e d e d e d i n d e d i d e d i d e d i d i n g 8. Process according to claims 2 and 3, characterized in that it further comprises the step of separating the ethanol from the etherified product before mixing it with the final gasoline product. Process according to claim 2, characterized in that the molar ratio of ethanol to iso-octenes fed to the etherification unit ranges from 1 to 8. 7. Förfarande enligt patentkrav 2, k e n e t e c e a n d e d e d e d e d e d e d e d e n 200 ° C, f e v e r e d e d e s 70 and 90 10 ° C. Process according to claim 2, characterized in that the etherification 10 is carried out at a temperature below 200 ° C, preferably at a temperature between 70 and 90 ° C. 8. Förfarande enligt patentkrav 2, Converted petroleum distillates to the active compound 2,4,4-trimethyl-1-penten and 2,4,4-trimethyl-2-penten. 15 9. Förfarande enligt patentkrav 8, A n d e c t a n d e n t a t e r t i o f 2,4,4-trimethyl-l-penten and 2,4,4-trimethyl-2-penten i det phthetylflow som tillförs företringsenheten motsvarar blandningens thermodynamically balan. Process according to claim 2, characterized in that the hydrocarbon feed of the etherification unit consists essentially of 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene. 15 8 111463 Process according to Claim 8, characterized in that the molar ratio of 2,4,4-trimethyl-1-pentene to 2,4,4-trimethyl-2-pentene in the hydrocarbon feed which is fed to the etherification unit corresponds to the thermodynamic equilibrium of the mixture. 10. Use of 2-ethoxy-2,4,4-trimethylpentane as a component of high octane motor gasoline. • * <»« 4 10 111463 1.Oxygeneradobenzene component, transducer av attdenomfattar - 2-ethoxy-2,4,4-trimethylpentane i en Quantity, som varierar mellan 2 and 20 v / v, 5-methyltert-butyleter under 1 v / v, ethanol i en Quantity, som varierar mellan 1 and 65 v / v%, och - iso-octener i en Quantity, som varierar mellan, 15 and 85 v / v%. 10. Användningen av 2-ethoxy-2,4,4-trimethylpentane isomassed in benzene med högt 20 octane.