This invention relates to selective formation of mono isopropyl ether of glycerol

In the field of bio-diesel production there is an increasing attention for the conversion of the by-product to value added products.

Even though a variety of value added products such as a mono isopropyl ether of glycerol and p mono isopropyl ether of glycerol can be formed by a catalytic etherification reaction, the formation of any of the products is still challenging. Secondly, it is also desirable in devising catalytic routes where the selectivity of the most value added product such as mono isopropyl ether of glycerol has to be optimized. These ethers can be used in a variety of applications such as antimicrobials, emulsifiers, surfactants, fragrance enhancers, moisture retaining agents, solvents and solvatropes. Glycerol ethers have been administered orally using capsules, which are available under the trademark ECOMER. Glycerol ethers are used in deodorant and antiperspirant composition.
As fuel additive : (a) glycerol ethers improve fuel combustion and reduce air pollution (b) glycerol ethers possess good solubility, high flash point, lower water affinity and negligible cetane reduction,(c) alkyl tertiary alkyl ethers are useful as octane improvers (d) they are useful for reducing the vapor pressure of the gasoline because of their low vapor pressure.

Appending one, two or three alkyl chain hydrophobes and/or cappfaig groups onto glycerol allows alkyl glycerol ethers to possess uniqiie physico1hemical and sohihihty properties that atto1 alkyl glycerol ethcrs to be tailored for nniltiple applications.

The process, according to this invention, for the s1ectiive formation of mono isopropyi ether of 1cerol comprises flie steps of reactbig 1cerol and isoprapyl alcohol (1:1 to 1:5 mole ratio) in a reactor wifli a cmtafyst selected tVom (i) H-Z8M-5 (SIOi/AliOj ratio rangjbig ihmi 30 - 250) (P) metal km exchanged or metal loaded ZSM-S such as Fe-ZBM-5 and Cu-ZSM-5 (Iti) H-hcta 9:eollte and ion eichange redn (Amberlyst-15) in an inert atmosphere of nitrogen, tiie entire mass bdng heated at a temperature between 423 ~ 473 K, with itlrrffig, the haated mass being kept for 6 hours and thereafter cooled to ambient temperature, to obtaion, mainly, mono isoprop3i ether of glycerol of netectMty 80-90 % and conyersion rate 14-40 % while that of other by products induding diether being relative1 low.

EXAIVKPLE

The reactants glycerol and isoprOpyl alcohol (1le ratki 1'.2) are introduced into a reactor wititi a catalyst H-ZSM-5 (SiOa/AlsOs ratio rang1g fk-om 30 -250 and 3 wt. % with respect to 11erol) in an faiert atmosphere of nltro1 under 20 bar pressure. The entire mass is heated to 180" C wifii sth'ring at 400 rpni. The heated maaa is kept for 6 hours and 1reatter cooled to ambient temperature, thai the product was sepal1ted tV1">* catatyst by fatratlon and unreacted Isopropanol, dl Isopropyl ettiers wtre removed by evaporation in rotoevaporator . The renaming product mixture contains mainfyf mono laopropji etfier of 0ycerol said dk iaopropji ellier of glyceroL Conversion of glycerol was 32% and this can be reaHied under typical experimental conditions. Selectivity for mono ethers is between 80 - 90 % while that of other products like diether is relatively low (10 - 15 %). The reaction can be carried out under inert atmosphere around 20 bar N2 at 423 -473 K. The catalyst is separated from the cooled mass and is re-usable.

Table:

Typical data generated on H-ZSM-5 (SiO2/Al2O3=30) catalyst for the
etherification of glycerol with isopropanol by varying the reactant mole
ratio

Glycerol: Conversion Mono ethers Di ether
Isopropyl I
alcohol 3-isopropoxy 2-isopropoxy 1,3-
1,2-propane 1,3-propane diisopropoxy
(mole ratio) ... ., , ^ ,
diol diol propane 2-ol
1:1 14 84 4.5 11.5
1:2 32 83.3 5.4 11.3
1:3 31 82 2 16
1:4 32 82.5 4 13.5
1:5 36 81.5 3.5 15

In the process set out herein the metal ion excluutged or metal loaded ZSM-5 (typical example being Fe-25SM-5 and Ci|-ZSM-5) aw employed for selective formation of isopropyl ethers of glycerol &om glycerol.

In the process proposed herein H-beta zeolite and ion exohan^e resin (Amberlyst-15) are employed but selectivity of mono isopropyl others of glycerol (65 %) were decreased.

We Claim

1. A process for the selective formation of mono isopropyl ether of glycerol comprising the steps of reacting glycerol and isopropyl alcohol (1:1 to 1:5 mole ratio) in a reactor with a catalyst selected from (i) H-ZSM-5 (SiO2/Al2O3 ratio ranging from 30 - 250) (ii) metal ion exchanged or metal loaded ZSM5 such as Fe-ZSM-5 and Cu-ZSM-5 (iii) H-beta zeolite exchange resin (Amberlyst-15) in an inert atmosphere of nitrogen, the entire mass being heated at a temperature between 423 - 473 K, with stirring, the heated mass being kept for 6 hours and thereafter cooled to ambient temperature, to obtain, mainly, mono isopropyl either of glycerol of selectivity 80-90 % and conversion rate 14 - 40 % while that of other by products including diether being relatively low.

2. A process as claimed in Claim 1 wherein the catalyst is 3 wt % with respect to glycerol.

3. A process as claimed in Claim 1 or Claim 2 wherein the stirring is carried out at 400 rpm.

4. A process as claimed in any one of the preceding Claims wherein the inert atmosphere of nitrogen is at 20 bar pressure.

5. A process for the selective formation of mono isopropyl ether of glycerol substantially as herein described with reference to, and as illustrated by, the
Example and the Table,