Title of Invention	PROCESS FOR SEPARATING THE HIGH-BOILING FRACTION FROM A CRUDE BUTYNE DIOL SOLUTION
Abstract	A process for separating the high-boiling fraction from a crude butyne diol solution already purified from fur¬ ther undesired constituents such as acetylene, formalde¬ hyde, propargyl alcohol or the like, characterized in that the high-boiling fraction is separated from the crude butyne diol solution in a flash column.

Full Text

The invention relates to a process for separating the high-boiling fraction from a crude butyne diol solution from which further undesired constituents such as acetylene, formaldehyde, propargyl alcohol or the like have already been removed. The crude butyne diol solution withdrawn from the butyne-diol synthesis still contains physically dissolved acety¬lene, unreacted formaldehyde, propargyl alcohol as well as further low- and high-boiling components. It is known to remove acetylene by means of a stripping column and then to supply the crude butyne diol solution to two vacuum distil¬lation columns arranged one behind the other. In the first vacuum distillation column formaldehyde and low-boiling components are removed from the crude butyne diol solution, whereas in the second vacuum distillation column the high-boiling components are separated and pure butyne diol is withdrawn at the top (see for instance Chem System Inc., Butanediol/Tetrahydrofuran-Report, No. 91S15, April 1993, page 22, Fig. II.B.l). The distillation in the second va¬cuum distillation column takes place at temperatures of diol solution leads to an increased formation of high-boil¬ing components during the first distillation. The content of high-boiling components disturbing the hydrogenation in¬creases to such an extent that, as has already been men¬tioned above, the same must be separated in an additional vacuum distillation column. The high-boiling components formed during the catalytic synthesis of butyne diol and in the subsequent process steps must be removed before the ca¬talytic butyne-diol hydrogenation, since on the one hand they would lead to a deterioration of the product and on the other hand would damage the hydrogenation catalyst. Be¬cause of the relatively long dwell time of the crude butyne diol solution in the second vacuum distillation column there also takes place an additional formation of polymers and high-boiling components. In addition, the columns re¬quired for the vacuum distillation are on the one hand ex¬pensive and on the other hand comparatively difficult to operate. The object of the invention is to separate the high-boiling fraction more easily from the crude butyne diol solution. In accordance with the invention this is achieved in that the high-boiling fraction is separated from the crude bu¬tyne diol solution in a flash column. The vacuum distilla¬tion column used so far is now replaced by a flash column. The crude butyne diol solution introduced in the flash co¬lumn and the fractions withdrawn at the top and at the bot¬tom of the flash column have a considerably shorter dwell time in the column than this is the case with a vacuum distillation column. Thus, the formation of polymers and high-boiling components can be reduced considerably. Since the difference in boiling temperature between butyne diol and high-boiling components is large enough, a content of high-boiling components in the butyne diol withdrawn at the top of the column can be achieved for the flash column which can be tolerated in the subsequent hydrogenation step. One embodiment of the process in accordance with the inven¬tion is characterized in that the crude butyne diol solu¬tion supplied to the flash column has a temperature between 120 and 170°C and a pressure between 5 and 50 rabar. Laboratory experiments have shown that at a temperature of 140°C and a pressure of 5 mbar in the flash column at the bottom of this column a butyne diol fraction with 99.5 % by weight butyne diol can be produced, which only contains 0.1 % by weight high-boiling components. In summary it can be noted that the process in accordance with the invention has several advantages over the known processes. There is for instance no need for a vacuum dis¬tillation column/ which is quite expensive as compared to a flash column. Furthermore, it is easier to regulate a flash column than a vacuum distillation column. Since a flash co¬lumn has no internal fittings such as trays or packings, the resulting operating costs are much lower. In conven¬tional distillation columns, these internal fittings become cemented by the high-boiling components in the course of time, so that possibly quite considerable pressure losses may occur. It is therefore necessary to clean the internal fittings from time to time. Such cleaning work becomes su¬perfluous when a flash column is used for separating the high-boiling components. The co-pending application No. 1039/MAS/95 relates to a process for separating undesired components, such as acetylene, formaldehyde, propargyl alcohol or the like, of the crude butyne diol solution withdrawn from the butyne diol synthesis. We Claims 1. A process for separating the high-boiling fraction from a crude butyne diol solution already purified from fur¬ ther undesired constituents such as acetylene, formalde¬ hyde, propargyl alcohol or the like, characterized in that the high-boiling fraction is separated from the crude butyne diol solution in a flash column. 2. The process as claimed in claim 1, characterized in that the crude butyne diol solution supplied to the flash co¬ lumn has a temperature between 120 and 170°C and a pres¬ sure between 5 and 50 mbar. 3. A process for separating the high-boiling fraction from a crude butyne diol, substantially as hereinabove described and exemplified.

Documents:

1040-mas-1995 claims.pdf

1040-mas-1995 correspondence-others.pdf

1040-mas-1995 correspondence-po.pdf

1040-mas-1995 description (complete).pdf

1040-mas-1995 form-1.pdf

1040-mas-1995 form-26.pdf

1040-mas-1995 form-29.pdf

1040-mas-1995 form-4.pdf

1040-mas-1995 form-6.pdf

1040-mas-1995 form-9.pdf

1040-mas-1995 others.pdf

1040-mas-1995 petition.pdf