FR2669628A1 - HYDROGENATION OF FATTY ESTERS. - Google Patents

Abstract

The subject of the invention is a process for the hydrogenation of fatty esters into alcohols using a copper / zinc catalyst. The activity of the catalyst is maintained by treatment with steam, for example, by incorporating 1.0 to 1.8% by weight of water in the ester feed. Preservation of catalyst activity for a long time.

Description

Hydrogenation of fatty esters The present invention relates to a process

  of hydrogenation of fatty esters and more particularly

  specifically, catalytic hydrogenation using a

catalyst that contains copper.

  By GB 2,116,552 (Davy Mckee) it is known that fatty esters, especially fatty acid methyl esters, can be hydrogenated by passing the ester together with hydrogen over a reduced CuO / Zn O catalyst. with

  formation of the corresponding fatty alcohol and methanol.

  The Applicant has found that as the use of

  continued use of the catalyst in this reaction, its

  activity is decreasing, ie the return of the

action decreases with time.

  The Applicant has now discovered that if a catalyst having such reduced activity is exposed to water vapor, at least part of its activity is

  restored so that it can be reused without any noticeable loss

performance.

  Thus, the invention provides a method of

  wherein a fatty alcohol is passed through which a fatty ester is passed together with hydrogen over a catalyst containing copper, characterized in that the catalyst is treated with steam to contribute to the maintenance of the

of his activity.

  The catalyst is treated with water vapor

  before or during contact with the fatty ester and the hydro-

  gene. According to a first embodiment of

  the invention, the hydrogenation process is carried out by

  In a first stage, the fatty ester and hydrogen are passed over the catalyst to produce the corresponding fatty alcohol.

  water vapor on the catalyst to regenerate the

  In a third stage, a supplement of fatty ester and hydrogen is passed over the catalyst to produce a new amount of fatty alcohol.

  this embodiment of the invention while retaining the cat-

  lyser in the reactor, cutting off the arrival of the fatty ester to the reactor and replacing it with an inlet of steam and then cutting off the steam inlet

  water and restoring the arrival of ester to the reactor.

  The arrival of hydrogen gas to the reactor can now be

  naked during the distribution of water vapor.

  This embodiment of the invention has the advantage that water vapor after passage over the catalyst can be separately collected and adulterated.

  not significantly the fatty alcohol produced.

  In a second mode of implementation of the in-

  In this case, the catalyst feed comprises a mixture of fatty ester and water together with hydrogen. The proportion of water which is added to the fatty ester charge

  can be between 0.1 and 2% by weight, for example

  from 1.0 to 1.8% by weight and especially about 1%.

  Alternatively, the water vapor can be admitted continuously

  in the arrival of hydrogen gas.

  This embodiment allows the hydrogenation reaction to be carried out continuously. In this way, sufficient water vapor can be passed over the catalyst to stabilize the activity. is drawn into the fatty alcohol produced and it may, therefore, be necessary to eliminate it

  subsequently, for example by distillation.

  Without wishing to be bound by any theory

  the applicant believes that during the reaction of

  hydrogenation, the electronic state of copper in the

  The lyseur gradually changes, causing a loss of

  and the steam treatment causes a partial oxidation of Cu (O) to Cu (I), to regenerate its activity. It is not thought that the moisture content of the

  The catalyst plays an important role as the

  water vapor did not prove to be successful

  due to significant water absorption by the catalyst.

  The invention is particularly suitable for hydro-

  generation of fatty acid esters, which means according to

  the invention any evaporable ester of an

  carboxylic phage, especially esters derived from

  and natural fats, in particular the C 12-18 fatty acid esters with C 1 -C 5 alcohols, especially

with methanol.

  Preferably, the hydrolysis reaction is carried out

  at a temperature of 200 to 2300 C and under a pressure of

  from 3 to 5 M Pa. The molar ratio of the ester to the hydro-

  gene depends on the distribution of chain lengths of

  the ester charge and can be calculated from the

  the vapor pressure of this mixture is applied to the reaction pressure at the total pressure. Hydrogen gas itself is used although mixtures of

  this one with other gaseous components.

  The catalyst contains copper and is

  Such catalysts are known in the art, for example in GB 2,116,552 (Dacy McKee) already cited, GB 1,436,773 (Du Pont), US 3923694 (ICI) and US 4,283,581 (US Pat. Chevron) A representative catalyst comprises a reduced mixture of copper oxide and zinc oxide which may also contain other metal oxides

  as well as charges or supports such as coal.

  Preferably, the mixture Cu O / Zn O before reduction contains from 5 to 95%, for example from 10 to 70% by weight of Cu O and from 5%, for example 90 to 30% by weight of Zn O The others materials present do not normally constitute more than

% by weight of the catalyst.

  The catalyst can be prepared by known methods, for example by coprecipitation, calcination and

  reduction using hydrogen or carbon monoxide

  at a temperature of 160 to 250 ° C for 8 to 24 hours.

  The applicant is aware of the European patent

  EP-A-350,762 (Henkel) which discloses the gas phase dehydrogenation of aliphatic 1,2-diols containing from 5 to 60% by weight of water to form 1,2-ketone-alcohols in the presence of a catalyst containing copper is stipulated

  that in this process, water increases selectivity and

  premium dimerization without suppressing the activity The high

  thermal capacity of the water vapor retards the cooling

  ment. On the other hand, the present invention

  the activity of the catalyst used in a different reaction

  te, ie the hydrogenation of esters to alcohols,

  which is not suggested in any way by the description of

EP-A-350762.

  Example: In this example, the catalyst is a catalyst

  activated copper / zinc catalyst having a Cu / Zn weight ratio of 0.55 The catalyst is installed in a hydrogenation reactor. A mixture of C 12 18 methyl esters (flow rate 7 kg / h) is admitted into the reactor and hydrogen

  (750 Nm 3 / h) at a temperature of 205 ° C and under a pressure of

  4 M Pa The crude fatty alcohol is separated from the

  actor, the proportion of unconverted methyl esters

  used to calculate the efficiency of the hydrogenation reaction

  Hydrogen is recycled to the reactor inlet.

  In a first try, the initial conversion

  of the reaction is 97.2% After 50 hours, this

  ficiency drops to 97%. From this point on, we incorporate

  water in the diet at the rate of 1.2% by weight

  at the feed rate of methyl ester The conversion

  reaction then rises to 97.7% and remains at

  level as long as you keep the water in the load.

  In a second test, the initial conversion

  of the reaction is 97.6% After 50 hours, this conversion

  At this point, the charge is incorporated in the feed 1, 8% by weight of water. The conversion stabilizes at 97%. After 90 hours, the water level in the feed is reduced to 1%. % by weight The conversion remains at 97% After more hours, we cut the water inlet in the load and there is a notable drop in efficiency that falls

  below 96% after 60 hours more.

  This example demonstrates the introductory advantage

  of water in the ester / hydrogen charge to maintain the

catalyst activity.

Claims (7)

  Process for the preparation of a fatty alcohol according to which a fatty ester is passed together with hydrogen over a catalyst containing copper, characterized in that the catalyst is treated with steam for   contribute to the maintenance of its activity.   Process according to claim 1, characterized   in that a mixture of fatty ester and water is passed through   together with the hydrogen on the catalyst.   3. Process according to claim 2, characterized   rised in that the trapped water is subsequently removed in the fatty alcohol produced.   The method of claim 1, which is effected   in a first step, the fatty ester and hydrogen are passed over the catalyst, in a second stage the steam is passed over the catalyst and in a third stage a new amount of ester is passed over the catalyst fat and hydrogen.   Process according to claim 1, characterized   in that the catalyst is a copper-zinc catalyst.   Process according to claim 5, characterized   in that the catalyst is a reduced catalyst Cu O / Zn O.   The process according to claim 1, characterized   in that the fatty ester is the methyl ester of a fatty acid.   Process according to claims 2 and 7,   characterized in that the water entrained in the fatty alcohol product is separated therefrom together with the methanol   which is also formed in the reaction.