RU2376273C1 - C4-c16 isoalkane synthesis method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing a mixture of C₄-C₁₆ isoalkanes by bringing aliphatic alcohol - ethanol, 2-methyl-1-propanol, 3-methyl-1-butanol in an inert gas medium at 300-420°C, pressure 30-80 atm, bulk speed 0.2-0.8 h^-1, into contact with a catalyst composition, which contains a hydride phase of an iron-titanium intermetallic compound, modified with group IV-VII metals, aluminium-platinum catalyst and a transition metal oxide, characterised by that, the transition metal oxide used is magnesium oxide in mass ratio 10:1:(0.8-1.2).

EFFECT: catalyst used in the method is highly active for a long period of time and the given method also widens the raw material base of aliphatic alcohols used.

1 cl, 7 ex, 1 tbl

Description

The invention relates to the field of heterogeneous-catalytic conversions of organic compounds and, more specifically, to the catalytic conversion of aliphatic alcohols into a mixture of C ₄ -C ₁₆ isoalkanes.

Alkane fractions of isostructure, as you know, are the most valuable components of motor fuel, providing a high octane number, low pour point, as well as increased calorific value along with high storage stability.

In addition to fuels, isoalkanes are in demand as solvents and thinners for many organic industrial materials.

Considering that transport is one of the main sources of environmental pollution, special requirements have recently been placed on the composition of fuels, which leads to increased demand for isoalkanes that are most acceptable from an environmental point of view.

A single-stage method for producing C ₅ hydrocarbons from methanol in the presence of a zeolite with molecular filter properties is known [CN 1923770, class C07C 1/20, C07C 1/00, date 07.03.2007]. The disadvantages of this method include the low concentration of isoalkanes, as well as the narrow fractional composition of the light part of the gasoline fraction. In addition, the material used as raw material is not alcohol of biological origin.

The work [RU 2220940, class С07С 1/20, С07С 9/16, date 01/10/2004] describes a method for producing isoalkanes by contacting an aliphatic alcohol — isobutanol or isopentanol in an inert gas medium at 300–420 ° С, pressure 30–80 atm. , a space velocity of 0.1-0.8 h ^-1 with a catalytic composition containing the hydride phase of an iron-titanium intermetallic compound (IMS) modified with metals of groups IV-VII, and an alumina-platinum or alumina-nickel catalyst, taken in a mass ratio of 10: 1.

The disadvantage of this method is that it can be used for a limited number of bioalcohols, while they do not include the most common - ethanol.

There is also a method according to [RU 2220941, option 1, class C07C 1/20, C07C 9/16, date 01/10/2004], according to which a 40-60% aqueous solution of ethanol is contacted in a carbon dioxide medium at 350-380 ° C, a pressure of 8-12 atm and a space velocity of 0.2-0.8 h ^-1 , with a catalytic composition consisting of an IMC modified with metals of groups IV-VII and γ-alumina taken in a mass ratio of 10: 1.

The disadvantage of this solution is the high yield of oxygenates, as well as the low content of isoalkanes in the alkane fraction of C ₄ -C ₁₆ .

The closest solution to obtaining a mixture of isoalkanes is the work [RU 2220941, option 2, class C07C 1/20, C07C 9/16, date 10.01.2004]. This method involves contacting a 40-60% aqueous solution of a mixture of ethanol, isobutanol and isopentanol, taken in a mass ratio of 6: 1: 2, with a catalytic composition consisting of an IC modified with metals of groups IV-VII, an alumina-platinum catalyst and γ-alumina ( non-transition metal oxide) at a mass ratio of components in the composition of 10: 1: 1, in an inert gas at 300-420 ° C, a pressure of 30-80 atm and a space velocity of 0.2-0.8 h ^-1 .

The disadvantage of this method is the short period of time (10-12 hours) to maintain high activity of the catalytic composition.

The technical result of the invention is to maintain a high activity of the catalyst for an extended period of time.

This technical result is achieved by the method of producing C ₄ -C ₁₆ isoalkanes by contacting an aliphatic alcohol - ethanol, 2-methyl-1-propanol, 3-methyl-1-butanol in an inert gas (nitrogen, argon or carbon dioxide) at 300-420 ° C, a pressure of 30-80 atm, a space velocity of 0.2-0.8 h ^-1 with a catalytic composition containing an IC modified with metals of groups IV-VII, an alumina-platinum catalyst and MgO taken in the mass ratio is used as an oxide of a non-transition metal 10: 1: (0.8-1.2).

The conversion of ethanol, 2-methyl-1-propanol, 3-methyl-1-butanol to isoalkanes with a greater number of carbon atoms than in the starting alcohol, is realized at a relatively high pressure as a result of the tendency of the reagents to develop side condensation reactions, which lead to the formation of oxygenated products.

The proposed method involves the use of ICs of the following composition [TiFe _0.95 Zr _0.03 Mo _0.02 ], the types of alumina-platinum catalysts are AP-56, AP-64 (O.V. Krylov. “Heterogeneous catalysis”, ICC “Akademkniga ", M., 2004, S. 548-5 49], as well as the MgO additive, which improves the structure of the catalytic system by optimizing its specific surface area and increases the mechanical strength of the catalyst granules.

The catalytic composition was prepared by mechanical mixing of the IMC with Pt / γ-Al ₂ O ₃ and magnesium oxide in the ratio of IM: Pt / γ-Al ₂ O ₃ : magnesium oxide = 10: 1: (0.8-1.2).

Using capillary flow porometry, it was shown that the addition of magnesium oxide leads to an increase in the specific surface area.

The introduction of magnesium oxide additives in a ratio of 10: 1: (0.8-1.2) increases the mechanical strength of the catalyst granules. Its noticeable grinding in the absence of MgO occurs after 15-20 hours of continuous operation of the catalyst. In the presence of this additive, the catalytic system does not detect noticeable changes after 350-400 hours of continuous operation.

The following examples illustrate the implementation of the proposed method.

Example 1

A 50% aqueous solution of ethanol is passed through 66 cm ^{3 of a} catalyst consisting of a mixture of 55 cm ^{3 of the} hydride phase of the intermetallic compound [TiFe _0.95 Zr _0.03 Mo _0.02 ] H ₂ , 5.5 cm ³ Pt / γ- Al ₂ About ₃ and 5.5 cm ³ MgO (volume and mass ratio of the components 10: 1: 1) at a temperature of 350 ° C, with a bulk velocity of 0.5 h ^-1 under argon pressure of 50 atm. In the resulting product, the upper paraffin layer is separated from water, dried over CaCl ₂ , the liquid product is filtered off and distilled to a temperature of 250 ° C. The distilled off organic substrate was analyzed by chromatography-mass spectrometry and GLC in linear programming mode using a glass column (50 m × 0.2 mm) coated with an SE-30 phase and PID.

The results of the analysis showed that the conversion of ethanol is 87.3%, of which 18.6% are gaseous and 81.4% are liquid products. The organic reaction products contain 24.0% of oxygen-containing products and 60% of the C ₄ -C ₁₆ paraffin fraction containing up to 42.2% of isoalkanes, with 26.2% of them being dimethyl substituted and 16.0% from monomethyl substituted isoparaffins .

Data on the operation of the catalyst are summarized in table.

Example 2

The conversion of ethanol is carried out in the presence of a catalytic mixture of TiFe _0.95 Zr _0.03 Ni _0.02 + Pt / γ-Al ₂ O ₃ + MgO at a mass ratio of 10: 1: 0.8 under conditions similar to example 1.

The results of the analysis showed that the conversion of ethanol is 85.3%, of which 17.8% are gaseous and 82.2% are liquid products. The organic reaction products contain 23.0% of oxygen-containing products and 59% of the C ₄ -C ₁₆ paraffin fraction containing up to 40.1% of isoalkanes, 25.0% of which are dimethyl substituted, and 15.1% are monomethyl substituted isoparaffins .

Data on the operation of the catalyst are summarized in table.

Example 3

The conversion of ethanol is carried out in the presence of a catalytic mixture of TiFe _0.93 Mn _0.05 Cr _0.02 + Pt / γ-Al ₂ O ₃ + MgO at a ratio of 10: 1: 1.2 under conditions similar to example 1.

The results of the analysis showed that the conversion of ethanol is 86.5%, 18.3%, of which gaseous and 80.7% are liquid products. The organic reaction products contain 25.0% of oxygen-containing products and 60.7% of the C ₄ -C ₁₆ paraffin fraction containing up to 43.1% of isoalkanes, of which 27.1% are dimethyl substituted, and 16.0% monomethyl substituted isoparaffins.

Data on the operation of the catalyst are summarized in table.

Example 4

The conversion of ethanol is carried out in the presence of a catalytic mixture of TiFe _0.95 Zr _0.03 Mo _0.02 + Pt / γ-Al ₂ O ₃ + MgO at a mass ratio of 10: 1: 2 under conditions similar to example 1.

The results of the analysis showed that the conversion of ethanol is 84.7%, 16.9%, of which gaseous and 83.1% are liquid products. The organic reaction products contain 24% oxygen-containing products and 60% of the C ₄ -C ₁₆ paraffin fraction containing up to 41.2% of isoalkanes, 23.2% of which are dimethyl substituted, and 14.7% are monomethyl substituted isoparaffins.

Data on the operation of the catalyst are summarized in table. With continuous operation of the catalyst for 400 hours, its catalytic activity decreases by 20-25%. Example 5

The conversion of ethanol is carried out in the presence of a catalytic mixture of TiFe _0.95 Zr _0.03 Mo _0.02 + Pt / γ-Al ₂ About ₃ + MgO at a mass ratio of 10: 1: 0.5 under conditions similar to example 1.

The results of the analysis showed that the conversion of ethanol is 76.3%, of which 21.6% are gaseous and 78.4% are liquid products. The composition of the organic reaction products contains 28.0% of oxygen-containing products and 52.6% of the C ₄ -C ₁₆ paraffin fraction containing up to 43.6% of isoalkanes, of which 24.2% are dimethyl substituted, and 19.4% are monomethyl substituted isoparaffins.

Data on the operation of the catalyst are summarized in table. With continuous operation of the catalyst for 200 hours, its catalytic activity decreases by 20-25%, and after 400 hours - by 40%. Example 6

A 50% aqueous mixture of alcohols is converted, consisting of 30% ethanol, 5% 2-methyl-1-propanol and 15% 3-methyl-1-butanol (mass ratio 6: 1: 2) by passing it through 66 cm ^{3 of} catalyst consisting of a mixture of 55 cm ^{3 of the} hydride phase of the intermetallic compound [TiFe _0.95 Zr _0.03 Mo _0.02 ] H ₂ , 5.5 cm Pt / γ-Al ₂ O ₃ and 5.5 cm MgO under conditions analogous to the example one.

The reaction products had the following composition: gaseous compounds - 15%, liquid - 40%, of which 27% is the alkane fraction C ₄ -C ₁₆ , 13% are oxygen-containing compounds, the rest is water. The alkane fraction contains 83% of isoalkanes.

Example 7 (prototype)

A 50% aqueous solution of ethanol is passed through 66 cm ^{3 of a} catalyst consisting of a mixture of 60 cm ^{3 of the} hydride phase of the intermetallic compound [TiFe _0.95 Zr _0.03 Mo _0.02 ] H ₂ and 6 cm ³ γ-Al ₂ O ₃ under conditions similar to example 1. The results of the analysis showed that the conversion of ethanol is 70%, 5% of which falls on gaseous and 95% on liquid products. The organic reaction products contain 40% diethyl ether and 60% C ₈ -C ₁₅ paraffin fraction containing up to 45% isoalkanes, 30% of them being dimethyl substituted and 15% monomethyl substituted isoparaffins. After 20 hours of operation, significant grinding of the catalyst and its destruction occurs.

The table presents the results of the study of resource intensity (catalyst operating time without loss of activity) of all examples.

Resource Intensity Table of the Intermetallic Catalytic System

The operating time of the catalyst, hours. Catalytic activity (for alkanes), g / l _cat. h Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Prototype one 120 120 120 120 120 120 120 5 123 126 124 125 122 121 108 10 125 123 124 125 125 124 90 fifteen 121 120 121 121 121 121 81 twenty 118 122 122 118 117 120 70 thirty 121 120 120 115 115 118 fifty 120 118 116 112 112 116 one hundred 118 118 118 108 108 119 150 118 116 116 103 98 120 200 123 114 115 one hundred 93 118 250 125 116 113 98 85 116 300 121 113 111 95 75 119 350 117 112 111 93 72 117 400 116 112 110 90 68 117

Thus, from a comparable analysis it follows that in the proposed method (a catalyst containing MgO as the transition metal oxide), the operating time of the catalytic system while maintaining high catalytic activity increases to 400 hours, which is more than 20 times higher than the prototype.

Claims (1)

The method of obtaining a mixture of isoalkanes C ₄ -C ₁₆ by contacting an aliphatic alcohol - ethanol, 2-methyl-1-propanol, 3-methyl-1-butanol in an inert gas medium at 300-420 ° C, pressure 30-80 atm, space velocity 0.2-0.8 h ^-1 with a catalytic composition containing the hydride phase of an iron-titanium intermetallic compound modified with metals of groups IV-VII, an alumina-platinum catalyst and a transition metal oxide, characterized in that magnesium oxide is used as a transition metal oxide in a weight ratio 10: 1: (0.8-1.2).