Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
2001-11-21
2003-01-21
Carr, Deborah D. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
C554S162000
Reexamination Certificate
active
06509487
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for producing lower alkyl fatty esters from fatty acids in fixed-bed reactor(s) charged with a weakly acidic solid catalyst by countercurrent or pseudo-countercurrent operation.
PRIOR ART
The lower alkyl fatty esters have been produced from of old as the starting material for producing higher alcohols, and methyl fatty esters are generally obtained by reaction of triglycerides with methanol or by reaction of fatty acids with methanol. In the reaction of triglycerides with methanol, glycerin is formed as a byproduct, but the formed methyl fatty esters and glycerin are easily separated as different phases, and thus the reaction easily proceeds. On the other hand, the reaction of fatty acids with methanol is an equilibrated reaction so that unless water formed as a byproduct is efficiently removed, the apparent rate of the reaction is lowered or the equilibrium of the reaction is established at a higher concentration of remaining fatty acids, and thus the amount of the remaining fatty acids cannot be sufficiently lowered.
To solve these problems, JP-A 1-283251 discloses a method of using a multi-stage-plate reaction column and reducing the pressure in the top of the reaction column. In this method, removal of water is improved by reduced pressure, but the catalyst used in esterification is a uniform catalyst, so removal of the catalyst from the desired products i.e. methyl fatty esters is necessary.
On the other hand, JP-B 53-6161 discloses a process for producing lower alkyl fatty esters by means of a fixed bed. It is described that in this process, a mixed solution of fatty acid and alcohol is brought into contact with a catalyst layer and the alcohol is gasified, but in this process, the operation of only co-current of fatty acid and alcohol is conducted, and water formed as a byproduct is evaporated into the gas phase but partially remains from the relationship of gas-liquid equilibrium. As the reaction proceeds, the content of water in the gas phase particularly in the vicinity of an outlet of the reaction column is increased so that from the relationship of gas-liquid equilibrium, the content of water in the liquid phase is also increased, thus making it difficult to lower the amount of the remaining fatty acid because of the equilibrated reaction. For lowering the content of water in the liquid phase, a method of using a large amount of alcohol can be anticipated but is not economical.
JP-A 7-224002(JP-B2 2707063) discloses a fixed-bed system for esterification wherein a strong acid catalyst and ion-exchange resin are used as the catalyst.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide a process for producing lower alkyl fatty esters from fatty acids and lower alcohols, wherein lower alkyl fatty esters are produced in higher yield with a reduction in the amount of the remaining fatty acids.
The invention provides a process for producing a lower alkyl fatty ester, which comprises feeding a fatty acid and a lower alcohol in a fixed-bed reactor charged with a weakly acidic solid catalyst and reacting them with each other by bringing the fatty acid into contact with gas of the lower alcohol in countercurrent operation in the bed.
The invention also provides a process for producing a lower alkyl fatty ester, which comprises feeding a fatty acid and a lower alcohol in at least two fixed-bed reactors charged with a weakly acidic solid catalyst and reacting them with each other by bringing the fatty acid into contact with gas of the lower alcohol in co-current operation in one of the reactors and then in countercurrent operation in the other reactor. It is here preferable that the gaseous lower alcohol is first fed to the countercurrent fixed-bed reactor and then gaseous lower alcohol discharged from the outlet of the reactor is fed to the co-current fixed-bed reactor.
The invention then provides a process for producing a lower alkyl fatty ester, which comprises feeding a fatty acid and a lower alcohol in multi-staged fixed-bed reactors each charged with a weakly acidic solid catalyst and reacting them with each other by feeding the fatty acid to a reactor at an upstream stage and sending it to a stage at the downstream side, feeding the gaseous lower alcohol to a reactor at a downstream stage to carry out downward co-current operation and at the same time returning the gaseous lower alcohol discharged from the outlet of the reactor to a stage at the upstream side to repeatedly conducting a pseudo-countercurrent operation in the fixed bed of each reactor.
DETAILED DESCRIPTION OF THE INVENTION
The fatty acids used in this invention include, but are not limited to, saturated or unsaturated fatty acids obtained by hydrolysis of natural vegetable and animal fats and oils. The vegetable fats and oils include e.g. coconut oil, palm oil, palm kernel oil, soybean oil etc. The animal fats and oils include e.g. tallow, lard, fishoil etc. Further, organic acids such as dicarboxylic acids and tricarboxylic acids can be mentioned. These are used preferably in a liquid form.
The lower alcohols used in the present invention are preferably C
1-5
lower alcohols. Specifically, monoalkanols such as methanol, ethanol and propanol can be mentioned, and methanol is industrially preferable because of low cost and easy recovery.
It is preferable the weakly acidic solid catalyst has a strong acid point of not higher than 0.2 mmol/g-Cat and a weak acid point of not less than 0.3 mol/g-Cat, each acid point being defined as follows:
Weak acid point: the point at which desorption of NH
3
occurs in the range of 100 to 250° C. in TPD (ammonia adsorption-desorption process);
Strong acid point: the point at which desorption of NH
3
occurs at a temperature higher than 250° C. in TPD.
It is further preferable that the weakly acidic solid catalyst is a molded article of a weakly acidic solid catalyst having the structure (A), the structure (B) and the metal atom (C) as follows:
Structure (A): a structure of an inorganic phosphoric acid wherein the hydrogen atom is removed from at least one OH group thereof,
Structure (B): a structure of an organic phosphoric acid represented by the formula (1) or (2), wherein the hydrogen atom is removed from at least one OH group thereof:
wherein —R
1
and —R
2
is independently selected from the group consisting of —R, —OR, —OH and —H and at least one of —R
1
and —R
2
is —R or —OR, —R being a C
1-22
organic group, and
Metal atom (C): at least one metal atom selected from the group consisting of aluminum, gallium, and iron.
It is much preferable that the weakly acidic solid catalyst is a molded article of a heterogeneous catalyst comprising aluminum orthophosphate.
In the structure (A), the inorganic phosphoric acid includes orthophosphoric acid, metaphosphoric acid and condensed phosphoric acid such as pyrophosphoric acid, and in respect of performance, orthophosphoric acid is preferable. In the structure (B), the organic phosphoric acid represented by formula (1) or (2) includes phosphonic acid, monophosphonate, phosphinic acid, monophosphate, diphosphate, monophosphite and diphosphite or a mixture thereof, preferably phosphonic acid.
The organic group —R in the organic phosphoric acid is preferably an alkyl group such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-hexyl, 2-ethylhexyl, octyl, dodecyl and octadecyl, and an aryl group such as phenyl and 3-methylphenyl, to which an amino group, alkoxy group, carbonyl group, alkoxycarbonyl group, carboxylic acid group, halogen group such as chloro group, phosphonic acid group, sulfonic acid group may be added.
In respect of performance and/or cost, the metal atom (C) is preferably aluminum. For the purpose of improving performance such as selectivity etc., the catalyst may contain a small amount of metal atoms other than aluminum, gallium and iron. It is not always necessary that all metal atoms (C) contained in the catalyst are bonded to the structure (A) or (B), and therefore, a part of metal atoms (C) may be
Fukuoka Noriaki
Katayama Takanobu
Mimura Taku
Tabata Osamu
Tatsumi Nobuhiro
Carr Deborah D.
Kao Corporation
LandOfFree
Process for producing lower alkyl fatty esters does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing lower alkyl fatty esters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing lower alkyl fatty esters will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3067550