EP0145043B1 - Method for preparing a synthetic fuel and/or synthetic components for fuels, and the product obtained thereby - Google Patents

Abstract

A synthetic fuel and or synthetic components for fuels are prepared from a mixture of poiycarboxylic acids of suitable elementary composition, having a mean molecular weight of between 120 and 800 and an acidity of between 5 and 18 meq g, by esterifying the polycarboxylic acids with one or more alcohols or one or more olefins.

Description

• This invention relates to a method for preparing a synthetic fuel and/or synthetic components for fuels, and the product obtained by said method.
• Various methods are known for preparing synthetic fuels, in particular starting from coal by hydroliquefaction or pyrolysis, or starting from synthetic gases, but, all of them suffer from the drawback of involving high first and operating costs.
• Numerous methods exist for oxidising coal with oxygen, oxygen-containing gases or oxidising substances in an aqueous alkaline medium.
• The products of this oxidation mainly consist of polycarboxylic-acid mixtures.
• Examples of methods for producing polycarboxylic acids by oxidising coal include those described in FR--A-1 347 213 and in DE-A-841 140, DE-A-864 992 and DE-A-879 103.
• DE-A-2 701 062 discloses a method for esterifying polycarboxylic acids, and exemplifies isophthalic acid among others, indicating the possibility of using mixtures of acids: though not specifically indicated, these acid mixtures might lend themselves to formulations of fuel components.
• The polycarboxylic acids obtained by known methods, however, cannot be employed as fuels because of their acidic nature, so that their use is virtually limited to the chemical field.
• Our copending European Application 84201445.8 (EP-A-142876) discloses a process in which the polycarboxylic acid mixture is first subjected to decarboxylation prior to a subsequent esterification with alcohols or olefins.
• It has been surprisingly found that polycarboxylic acids can be converted into fuels and/or components for fuels by transforming them into oleophilic compounds in a simple and economical manner.
• The invention, therefore, provides a method for preparing a synthetic fuel and/or synthetic fuel components from a polycarboxylic-acid mixture, characterized in that the starting polycarboxylic-acid mixtures is obtained in the oxidative treatment of coals and has the following analytical composition:

  

  its mean molecular weight being between 120 and 800 and its acidity lying between 5 meq/g and 18 meq/g, said starting acidic mixture being thereafter esterified with at least one alcohol, or with at least one olefin.
• A preferred embodiment is the one wherein the starting acidic mixture has an acidity between 8 meq/g and 14 meq/g.
• According to another aspect of the invention, the esterification of the acids concerned is effected with at least one alcohol having from 1 to 10 carbon atoms, said alcohols being used in an H₂S0₄-solution at a concentration of between 5% and 20% on a weight basis.
• As an alternative, the esterification is effected with at least one olefin having from 2 to 10 carbon atoms.
• Finally, the invention further provides a fuel obtained by blending a synthetic fuel and/or at least one synthetic fuel-component as obtained by the process of claim 1, with a product selected from among:
• a) medium petroleum distillates;
• b) medium distillates from coal hydroliquefaction;
• c) coal-pyrolysis products;
• d) fuel oil of petroleum origin;
• e) mixtures of aromatic hydrocarbons, and
• f) mixtures of C1-C10 aliphatic alcohols.
• Preferably, said coal-pyrolysis product (c) is a mixture of benzene, toluene and xylenes.
• An illustrated example is reported hereinafter, to better illustrate the process according to the invention, its products and the favourable results obtained thereby.
Example
• Coal oxidation products having the characteristics given in Table 1 were treated in the following manner:
• 30g of product plus 170 cm³ of methanol and 2.7 ml of H₂S0₄ are refluxed for 4 hours.
• The reaction mixture is poured into 200 ml of H₂0.
• The methyl esters are extracted with ethyl ether, which is then distilled off. The resultant mixture is blended with a medium distillate having the characteristics given in Table 2.
• Table 3 gives the characteristics of the fuel blend which is obtained.

  

  

  

Claims (6)

1. A method for preparing a synthetic fuel and/or synthetic fuel components from a polycarboxylic-acid mixture, characterized in that the starting polycarboxylic-acid mixture is obtained in the oxiditive treatment of coals and has the following analytical composition:

its mean molecular weight being between 120 and 800 and its acidity lying between 5 meq/g and 18 meq/g, said starting . acidic mixture being thereafter esterified with at least one alcohol, or with at least one olefin.

2. Method according to claim 1, wherein the starting acidic mixture has an acidity between 8 meq/g and 14 meq/g.

3. Method according to claim 1, wherein the esterification of the acids concerned is effected with at least one alcohol having from 1 to 10 carbon atoms, said alcohols being used in an H₂S0₄-solution at a concentration of between 5% and 20% on a weight basis.

4. Method according to claim 1, wherein the esterification is effected with at least one olefin having from 2 to 10 carbon atoms.

5. A fuel obtained by blending a synthetic fuel and/or at least one synthetic fuel-component as obtained by the process of claim 1, with a product selected from among:

a) medium petroleum distillates;

b) medium distillates from coal hydroliquefaction;

c) coal-pyrolysis products;

d) fuel oil of petroleum origin;

e) mixtures of aromatic hydrocarbons, and

f) mixtures of C1-C10 aliphatic alcohols.

6. Fuel according to claim 5, wherein said coal-pyrolysis product c) is a mixture of benzene, toluene and xylenes.