TWI498315B - A process for the preparation of primary alkyl glycerol ethers useful as biofuel additive from glycerol - Google Patents

Description

Method for preparing a grade alkyl glyceryl ether as a raw material fuel additive from glycerin

This invention relates to a process for preparing a biofuel or biofuel additive from glycerol. More specifically, it relates to a process for preparing a glyceryl ether by etherification of glycerol and an alcohol using a solid acid catalyst.

Glycerol is a by-product of the production of biodiesel via transesterification of triglycerides with alcohols such as methanol. In this process, the large amount of glycerol produced is not used as part of the biofuel. At present, the application found by glycerol is only a very small amount of products in the pharmaceutical industry. Other stages of glycerin use include mixing animal faecal fertilizers to form fertilizers, and mixing feeds to animals. If a large amount of glycerin is found, the economics of biodiesel production can be significantly improved. It is expected to find a method for converting a glycerin-containing stream into a more expensive substance by transesterification of vegetable or animal fat to improve the economics of biodiesel production. Glycerol ethers have been found to be useful as a blending component in, for example, gasoline or diesel fuels, and converting glycerol to glycerol ether is an attractive option from the standpoint of the large demand for such mixed components. Through the transesterification of triglyceride, the crude glycerin by-product produced by the production of biodiesel is not soluble in biodiesel. In order to mix biodiesel, glycerol must be converted into a boiling product in the range of diesel internal combustion engines, in addition, and completely Dissolved in biodiesel.

U.S. Patent Nos. 6,174,501 and 6,015,440 each disclose the production of a biodiesel fuel having a reduced viscosity and a cloud point below 32 degrees Fahrenheit, wherein the triglycerides are in a liquid phase reaction with methanol and, for example, NaOH. The homogeneous alkaline catalyst reacts to produce a methyl ester and a glycerin phase comprising primarily glycerol and some residual methanol. The glycerol phase is exchanged by strong cations to remove anions, producing a neutral product which is rapidly removed from the methanol and then reacted with an olefin such as isobutylene or isoamylene in the presence of a strong acid catalyst to produce a glyceryl ether. The glyceryl ether is then added back to the glycerol methyl ester to provide improved biodiesel. U.S. Patent No. 5,476,971 describes the reaction of pure glycerol with isopropene in a two phase reaction in the presence of an acid catalyst to produce mono-, di- and tri-tert-butyl ethers of glycerol. Among the three patents mentioned above, isobutylene is required as an etherifying agent. Since triglycerides are obtained from vegetable oils such as soybean oil, palm oil and rapeseed oil, and olefins such as isobutylene and isoamylene are obtained from catalytic fractionation of petroleum fractions, they are expected to be used as etherifying agents. Chemicals are used in the agricultural industry, such as agricultural ethanol. Biodiesel containing only blended components that are not derived from fossil fuels can be truly referred to as "biomass fuels." Further, a chemical compound containing a third alkyl carbon atom such as isobutylene, and a glyceryl ether containing an olefin such as isobutylene or isopentene have biodegradability lower than those containing only one primary carbon atom, such as ethanol or butyl. An alcohol or a glyceryl ether produced from such an alcohol. Therefore, there is a need for a process in which a primary alcohol can be used, and preferably a monohydric alcohol such as ethanol can also be obtained from the agricultural industry to etherify glycerol.

Etherification techniques are well known in the art, and etherification reactions involving alcohols as etherifying agents are more difficult to achieve than those using olefins as etherifying agents. In particular, the etherification involving olefins is less subject to equilibrium than the use of alcohols and the production of water as a by-product thereof. More specifically, the water produced by the transesterification can block the acidic part, and the acidic part is the active part of the transesterification. As a result, those catalysts which are quite effective in etherification with olefins, such as cation exchange resins, have a decrease in utility when alcohols are used as etherifying agents. In addition, the continuous removal of water formed during the reaction also favors the reaction-prone product side. It is also advantageous to carry out the etherification reaction at a temperature above the boiling point of water (100 ° C), since above 100 ° C, the formed water can be continuously removed by the catalyst. One disadvantage of using a cation exchange resin for the etherification reaction above 100 ° C is that the structure of these polymeric resins at temperatures above 100-120 ° C is not stable, so irreversible structural decomposition occurs at the above temperatures.

Purpose of the invention

SUMMARY OF THE INVENTION A primary object of the present invention is to provide a process for the preparation of glycerol-derived ethers and the use of them as additives for biofuels or biofuels.

Another object is to provide a single step process for the preparation of glyceryl ether from a glycerol fraction of a vegetable oil and animal fat transesterification product.

Another object of the present invention is to produce a glyceryl ether by etherification of a glycerol fraction obtained by transesterification of a vegetable oil or fat having a C1-C8 alcohol on a solid catalyst under suitable conditions with a shorter reaction time.

Summary of the invention

Accordingly, the present invention provides a process for the preparation of a primary alkyl glyceryl ether comprising, in the presence of a solid acidic catalyst, at a temperature in the range of from 60 to 300 ° C, in a molar ratio of primary alcohol to glycerol of from 3:1 to 9:1. Between the ranges, the primary alcohol and glycerol are reacted in a continuous stirred tank reactor, or at a weight hourly space velocity of about 0.2 h ^-1 in a fixed bed reactor, for 5-8 hours, and The known method separates the desired glycerol ether formed from the above reaction mixture.

In a particular embodiment of the invention, the primary alcohol used is selected from the group consisting of methanol, ethanol, butanol, and octanol.

In another embodiment of the invention, the molar ratio of primary alcohol to glycerol is preferably in the range of from 4:1 to 6:1.

In another embodiment, the solid acidic catalyst used is selected from the group consisting of alumina, aluminosilicate, yttrium aluminum phosphate, solid phosphoric acid, sulfated zirconia, sulfonic acid or thiol functionalized cerium oxide, and cation exchange resins. The group formed.

In another embodiment, the aluminosilicate used is selected from the group consisting of zeolite beta, zeolite Y, and mordenite.

In another embodiment, the cation exchange resin used is Amberlyst-15.

In another embodiment, the reaction temperature used is preferably in the range of from 60 to 150 °C.

In another embodiment, the reactor used is selected from the group consisting of a continuous stirred tank reactor, a reactive distillation reactor, and a continuous flow fixed bed reactor.

In another embodiment, the glycerol used is glycerol obtained from a by-product of vegetable oil or a transesterification of a fat with an alcohol.

In another embodiment of the invention, the glycerin-containing material further comprises glycerides and carboxylic acid esters in addition to glycerin.

In another embodiment, the glycerol conversion % is in the range of 60 to 95% by weight.

In another embodiment, the yield of glyceryl ether obtained is in the range of from 50 to 100% by weight of the glycerol used.

Detailed description of the invention

The present invention describes a process for producing a glyceryl ether, and more particularly, a process for producing a glyceryl ether by etherifying glycerol with a primary alcohol using a solid acid catalyst. The method comprises the steps of: reacting a mixture of a primary alcohol and a glycerin-containing raw material with a solid catalyst in a temperature range of 60 to 300 ° C and a pressure of 1-10 bar in a reactor, and separating most of the reaction mixture Glycerol ether.

The glycerin-containing feedstock is conveniently obtained from the transesterification products of triglycerides provided by vegetable oils, and the transesterification of glycerides with methanol to produce biodiesel is well known in the art. In general, a base catalyst such as NaOH or KOH is used for the liquid, and a homogenous phase is used. There are a number of disadvantages in using such catalysts: (1) if free fatty acids are present in triglycerides (and they are present in large amounts, otherwise all are vegetable oils), in which case pre-esterification must be carried out to neutralize Otherwise, the base catalyst will be combined and deactivated; (2) the sodium ions in the reaction product must be removed from the unsatisfactory acid neutralization step environment (involving the treatment of acid sludge) or in the cation exchange resin Expensive removal (and final treatment of sodium salt). A solid catalyst which can be subjected to a transesterification reaction will be advantageous, and the same is described in the co-pending Indian Patent Application Nos. 2722 DEL 2005 and 1561 DEL 2005, the use of a solid catalyst for the transesterification of a vegetable oil with an alcohol.

A waste liquid which is transesterified with a vegetable oil on a solid catalyst is described in more detail in the above-mentioned co-pending Indian Patent Application: 1561 DEL2005 and 2722DEL2005, containing two non-mixable, separated liquid phases, one of which is a light non-polar layer, mainly containing fatty acid alkyl (methyl or ethyl) esters (biodiesel diesel filter), and the other is polar A heavy liquid layer containing glycerin and unreacted alcohols (methanol or ethanol). The glycerin-containing and alcohol-containing filter fraction obtained after decantation to remove the raw diesel oil fraction can be, for example, added with an alcohol to form a suitable raw material for use in one of the methods of the present invention. It is noted that the use of a solid catalyst in place of caustic in the transesterification stage, as taught in the above-mentioned co-pending Indian Patent Application Nos. 2722 DEL 2005 and 1561 DEL 2005, has been excluded in the preparation of glycerol starting materials for the etherification process. Demand for caustic removal and pickling stages.

If desired, after adjusting the alcohol to glycerol molar ratio above 4, the glycerol and alcohol containing feedstock is contacted with the solid acidic catalyst again in the reaction zone most suitable for the reaction conditions of the etherification reaction. The inventors have found that depending on the nature of the triglycerides, temperatures in the range of from 60 to 300 ° C are very suitable for this reaction. The reaction proceeds to the autogenous pressure of the alcohol at the reaction temperature. The reaction zone may consist of a continuous stirred tank reactor (CSTR) or a continuous fixed bed reactor where a residence time of about 3 hours or longer is sufficient. Conversely, in a continuous fixed bed reactor, the hourly weight space velocity (WHSV) (defined as the total feed weight per gram of catalyst per hour through the reactor) is above 0.2, resulting in a complete conversion of glycerol to a different glycerol -, bis- and triethers. The relative proportions of the three ethers can be controlled by the molar ratio of alcohol to glycerol, with a high ratio leading to mainly di- and triethers, while monoethers account for a small proportion. The choice of alcohol is determined by the end use of the glycerol ether: if glycerol ether is used as a mixed component of biodiesel, methanol and ethanol are preferred alcohols. Meanwhile, if glycerin ether is used as the raw material lubricating oil, octanol is the selected alcohol. From the viewpoint that the primary alcohol has good biodegradability, the primary alcohol is preferred to the secondary and tertiary alcohols. Therefore, if the target is to produce biomass diesel, methanol or ethanol is used for the transesterification and etherification reaction. On the other hand, if the main purpose is to produce a raw lubricating oil, octanol is used in this case. It is to be noted that the above-mentioned co-pending Indian Patent Application Nos. 2722 DEL 2005 and 1561 DEL 2005 provide a method of producing biodiesel using methanol/ethanol or using n-octanol as a transesterified alcohol to produce a bio-based lubricating oil.

The solid catalyst used in the process of the invention can be any solid acid which contains a substantial amount of Lewis or Brönsted acid sites on the surface. Examples of the solid acid include alumina, bauxite, strontium alumina, amorphous alumina, solid phosphoric acid, zeolites such as zeolite Y, zeolite beta, mordenite, mesoporous zeolite, yttrium aluminum phosphate, and Valence metal aluminum phosphate, sulfated zirconia, and pickled clay. The primary alcohol used in the present invention is selected from the group consisting of methanol, ethanol, butanol, and octanol, preferably agricultural-ethanol obtained from agricultural products such as sugar cane and containing a large amount of water. The solid catalyst used in the present invention is a solid acidic catalyst, preferably alumina, alumina, aluminosilicate molecular sieve, yttrium aluminum phosphate molecular sieve, pickled clay, solid phosphoric acid, or sulfated zirconia.

The invention is illustrated by the following examples, which are merely illustrative and are not intended to limit the scope and extent of the invention.

Example 1

This example illustrates the preparation of glycerol diethyl ether on a gamma alumina catalyst. In the code For the preparation, ethanol and glycerol with a molar ratio of 5:1 and gamma alumina catalyst (5% by weight of the total reaction mixture) were heated in a closed pressure cooker at 100 ° C for 5 hours. The solid acid catalyst-gamma alumina was obtained from a commercial source, and before use in the etherification reaction, the solid catalyst was pretreated and activated at 500 ° C by a catalyst manufacturer's recommended and familiar procedures. After the end of 5 hours, the solid catalyst was removed and the glycerol ether was separated from unreacted glycerol, water and alcohol by extraction (in water) and a combination of distillation procedures, and the product was analyzed by gas chromatography.

Example 2

This example illustrates -β zeolite catalyst (silicon dioxide / alumina = 40; surface area = 550m ² / g, size = 0.1 to 0.5) was prepared on the glycerol ether. In a typical preparation, ethanol and glycerol having a molar ratio of 5:1 and zeolite-β (5% by weight of the total reaction mixture) were heated in a closed pressure cooker at 100 ° C for 5 hours. The solid catalyst was pretreated at 450 ° C for activation. After the end of the reaction, the catalyst was removed and the glycerol ether was separated from unreacted glycerol, water and alcohol by extraction (in water) and a combination of distillation procedures, and the product was analyzed by gas chromatography.

Example 3

This example illustrates -Y zeolite catalyst (silicon dioxide / alumina = 8; surface area = 420m ² / g) Preparation of the glycerol ether. In a typical preparation, ethanol and glycerol having a molar ratio of 5:1 and zeolite-Y (5% by weight of the total reaction mixture) were heated in a closed pressure cooker at 100 ° C for 5 hours. The solid catalyst was pretreated at 450 ° C for activation. After the end of the reaction, the catalyst was removed and the glycerol ether was separated from unreacted glycerol, water and alcohol by extraction (in water) and a combination of distillation procedures, and the product was analyzed by gas chromatography.

Example 4

This example illustrates the preparation of glyceryl diethyl ether on a ruthenium phosphate catalyst. In a typical preparation, ethanol and glycerol having a molar ratio of 5:1 and a catalyst (5% by weight of the total reaction mixture) were heated in a closed pressure cooker at 100 ° C for 5 hours. The solid catalyst was pretreated at 350 ° C for activation. After the end of the reaction, the catalyst was removed and the glycerol ether was separated from unreacted glycerol, water and alcohol by extraction (in water) and a combination of distillation procedures, and the product was analyzed by gas chromatography.

Example 5

This example illustrates the preparation of glyceryl ether on an Amberlyst-15 cation exchange resin (strongly acidic, macroreticular resin having a sulfonic acid function, Aldrich Co.). In a typical preparation, ethanol and glycerol having a molar ratio of 5:1 and Amberlyst-15 (5% by weight of the total reaction mixture) were heated in a closed pressure cooker at 100 ° C for 5 hours. The resin was pretreated with 3 M H ₂ SO ₄ and activated at 100 ° C before use. After the end of the reaction, the catalyst was removed and the glycerol ether was separated from unreacted glycerol, water and alcohol by extraction (in water) and a combination of distillation procedures, and the product was analyzed by gas chromatography.

Example 6

This example illustrates the preparation of glycerol diethyl ether on solid phosphoric acid. In a typical preparation, ethanol and glycerol having a molar ratio of 5:1 and solid phosphoric acid (5% by weight of the total reaction mixture) were heated in a closed pressure cooker at 100 ° C for 5 hours. After the end of the reaction, the catalyst was removed and the glycerol ether was separated from unreacted glycerol, water and alcohol by extraction (in water) and a combination of distillation procedures, and the product was analyzed by gas chromatography.

Example 7

This example illustrates the preparation of glycerol diethyl ether from glycerol and agricultural-ethanol (5% water) on a zeolite-beta catalyst (ceria/alumina = 40; surface area = 550 m ² /g, size = 0.1-0.5 μm). . In a typical preparation, agricultural-ethanol (5% water content) with a molar ratio of 5:1 and glycerol and zeolite-β (5 wt% of the total reaction mixture) were heated in a closed pressure cooker at 100 ° C for 5 hours. . The solid catalyst was pretreated at 450 ° C for activation. After the end of the reaction, the catalyst was removed and the glycerol ether was separated from unreacted glycerol, water and alcohol by extraction (in water) and a combination of distillation procedures, and the product was analyzed by gas chromatography.

Example 8

This example illustrates -β zeolite catalyst (silicon dioxide / alumina = 25; surface area = 550m ² / g, size = 0.1 to 0.5) was prepared on the glycerol ether. In a typical preparation, butanol and glycerol having a molar ratio of 5:1 and zeolite-β (7.5% by weight of the total reaction mixture) were heated in a closed pressure cooker at 60 ° C for 8 hours. The solid catalyst was pretreated at 450 ° C for activation. After the end of the reaction, the catalyst was removed and the glycerol ether was separated from unreacted glycerol, water and alcohol by extraction (in water) and a combination of distillation procedures, and the product was analyzed by gas chromatography.

Example 9

This example illustrates -β zeolite catalyst (silicon dioxide / alumina = 25; surface area = 550m ² / g, size = 0.1 to 0.5) was prepared on the glycerol ether. In a typical preparation, butanol and glycerol having a molar ratio of 5:1 and zeolite-β (7.5% by weight of the total reaction mixture) were heated in a closed pressure cooker at 90 ° C for 8 hours. The solid catalyst was pretreated at 450 ° C for activation. After the end of the reaction, the catalyst was removed and the glycerol ether was separated from unreacted glycerol, water and alcohol by extraction (in water) and a combination of distillation procedures, and the product was analyzed by gas chromatography.

Table 1 lists the results of the etherification reaction of the different catalysts described in Examples 1-9.

The invention is capable of many modifications, alternatives and modifications and The present invention can be embodied in other ways than the embodiments, and the scope and extent should be limited only by the scope of the patent application.

Claims (9)

A method for preparing a primary alkyl glyceryl ether, comprising: activating a catalyst; in the presence of a solid acidic catalyst, at a temperature ranging from 60 to 300 ° C, a molar ratio of primary alcohol to glycerol is 5:1, and the primary alcohol is The reaction mixture with glycerol is separated from the reaction mixture in a continuous stirred tank reactor or at a weight space velocity of about 0.2 h ^-1 per hour in a fixed bed reactor after 5-8 hours of reaction. Desire of glycerol. The method of claim 1, wherein the primary alcohol used is selected from the group consisting of methanol, ethanol, butanol, and octanol. The method of claim 1, wherein the solid acidic catalyst used is selected from the group consisting of alumina, aluminosilicate, yttrium aluminum phosphate, solid phosphoric acid, sulfated zirconia, sulfonic acid or thiol functionalized cerium oxide. And a group consisting of cation exchange resins. The method of claim 3, wherein the aluminosilicate used is selected from the group consisting of zeolite beta, zeolite Y, and mordenite. The method of claim 3, wherein the cation exchange resin used is Amberlyst-15. The method of claim 1, wherein the reaction temperature used is in the range of 60 to 150 °C. The method of claim 1, wherein the glycerin used is optionally glycerin obtained from a by-product of vegetable oil or a transesterification of a fat with an alcohol. The method of claim 1, wherein the conversion % of the glycerin is in the range of 60 to 95% by weight. The method of claim 1, wherein the yield of the glyceryl ether obtained is in the range of 50 to 100% by weight of the glycerin used.