FORM NO 2
THE PATENTS ACT, 1970 (39 OF 1970)
COMPLETE SPECIFICATION
[See sections 10 and Rule 13]
TITLE PROCESS FOR MANUFACTURE OF
GAMMA BUTYROLACTONE BY
CATALYTIC DEHYDROCYCLISATION OF 1,4 BUTANEDIOL
APPLICANT BALAJI AMINES LIMITED
ADDRESS 165/A, Balaji Bhavan, Railway Lines,
Solapur- 413 001.
NATIONALITY Indian
The following specification describes the nature of this invention and the manner in which it is to be performed:

TITLE
PROCESS FOR MANUFACTURE OF GAMMA BUTYROLACTONE BY CATALYTIC DEHYDROCYCLISATION OF 1,4 BUTANEDIOL.
FIELD OF INVENTION
This invention relates to the process for manufacture of Gamma butyro lactone (GBL) from 1,4-butane diol by dehydro cyclisation process using copper catalyst at 205-210°C. The liberated hydrogen is used as a source of fuel for thermic fluid boiler.
BACKGROUND OF THE INVENTION
Gamma butyro lactone (GBL) is used as a solvent, intermediate and starting material in various chemical and pharmaceutical preparations. GBL is also used as a feed stock for the production of many pyrrolidone derivatives such as 2-pyyrolidone, N-methyl pyrrolidone, N-ethyl pyrrolidone etc.
Gammabutyrolactone is manufactured by different routes and one of them is catalytic hydrogenation of maleic anhydride. Catalytic hydrogenation of maleic anhydride leads to the formation of various other hydrogenated products like succinic anhydride, tetrahydrofuran, butane diol, propanol, butanol, and butyric acid along with gammabutyrolactone. Hence commercial production of Gammabutyrolactone from maleic anhydride has not been entirely

successful in terms of conversion and selectivity of the reaction for
producing GBL
Process for preparing Gammabutyrolactone (GBL) from 1,4-butane
diol is described in Ullmann's Encyclopedia of chemistry 3rd Edition
1953 Vol: 4 pages 802-803
The process for manufacture of GBL is described in various patents;
US pat 3,065,243, US patent. 3,580,930, EPA 332140,
US pat 6,093,677, Canadian patent, 041,529 using various catalysts
and process conditions. All the above mentioned method found
unsatisfactory usually because either the catalyst is deactivated
through formation of tar or coke in the reaction or due to low
conversion and selectivity of the reaction.
OBJECTIVE OF THE INVENTION
The object of the present invention is to manufacture of Gamma butyro lactone by catalytic dehydro cyclisation of 1,4-butane diol at 205-220°C. It is also object of this invention to develop a low cost and economical method to develop the process to manufacture Gamma butyrolactone and thereby reduce utilities in terms of investments and consumptions thereby enhancing the economic significance to manufacture Gamma butyro lactone. It also the object of this invention to develop the green process for manufacture of Gamma butyro lactone by utilization the liberated hydrogen as a fuel for thermic fluid boiler for heating reaction mass and minimizing the use coal in the process thereby reducing the release green houses gases in to the atmosphere.

SUMMARY OF THE INVENTION
This invention is a method for manufacture of Gamma butyro lactone by dehydro cyclisation of 1,4-butane diol in the gas phase in the presence of copper catalyst.

This invention is advantageous for industrial production of GBL in terms of economy and ecological reasons due to use of byproduct hydrogen gas as fuel in thermic fluid bciler as it is not only minimizes the production cost also minimizes the pollution.
The copper catalyst used in this process displays excellent selectivity and high conversion rate leading to the formation of fewer impurities in the reaction and enhances greatly the purity of the final product GBL.
The unique type of heat recovery system used in the manufacturing process of GBL from 1,4-butanediol makes the process highly economical

DETAILED DISCRIPTION OF THE INVENTION
1,4-Butanediol is pre heated to about 200-210°C in a heat exchanger to vaporize the feed. The vapors of 1,4-Butanediol are fed through the tubular reactor containing copper catalyst at 205- 250°C under the pressure of 3-5 kgs/cm2 in the presence hydrogen gas. The reaction products containing GBL 97%. About 1.0% unreacted butane diol, 1 % Tetrahydrofuran (THF) and hydrogen gas are flashed in to a gas liquid separator. The gases (mainly hydrogen) containing traces of THF and butane diol are passed through a scrubber where hydrogen gas is purified to the level of above 99%. The purified hydrogen gas is compressed and sent to storage tank and used as fuel for hydrogen fired boiler for heating thermic fluid.
The liquids from the gas liquid separator mostly contain GBL and other impurities are sent to series of distillation column for purification of GBL to above 99% purity.

WE CLAIM:
1. The process for manufacture of Gammabutyrolactone from 1, 4-butanediol by dehydrocyclisation preferable at a temperature of 205-220 ° C in the presence of copper catalyst wherein the reaction is carried out with the help of hydrogen gas.
2. A process as claimed in Claim 1 above wherein, the conversion of 1, 4-butanediol to Gammabutyrolactone is minimum 98% and reaction selectivity is above 98% at a preferable temperature range of 70 - 240 ° C.
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3. A process as claimed in claims 1 and 2 above where in, hydrogen gas formed in the reaction is purified to the minimum of 99.5% using water scrubber.
4. A process as claimed in claims 1, 2 and 3 above wherein, hydrogen gas is used as fuel for boiler for heating thermic fluids used in the manufacture GBL.
5. A process as claimed in claims 1, 2, 3 and 4 above wherein, the heat from the reaction mass is recovered by circulating the feed (1, 4-butanediol) through heat exchanger.
6. A process to manufacture GBL from 1, 4-butanediol as described herein above.