Process for the separation of a product mixture
The invention provides the use of a clearing gas in the separation of a mixture comprising a light and a heavy component that are difficult to separate. The invention further concerns a process for such a separation, comprising (a) providing a product mixture containing at least a light component and a heavy component, wherein a binary system of the light component and the heavy component has a Henry's law constant of at least 0.001 mol m −3 Pa −1 , and the boiling point of the light component is at least 30° C. higher than the boiling point of the heavy component, determined at ambient pressure; (b) subjecting the product mixture to a distillation step, wherein the product mixture is heated in a distillation column to a distillation temperature at a distillation pressure; (c) feeding a clearing gas at a location below the feed point of the product mixture; (d) collecting at the top of the distillation column a product gas containing the light component and the clearing gas; (e) collecting at the bottom of the distillation column a product liquid containing the heavy component.
1 . A process for the separation of a product mixture, the process comprising:
(a) providing the product mixture containing at least a light component and a heavy component, wherein a binary system of the light component and the heavy component has a Henry's law constant of at least 0.001 mol m −3 Pa −1 , and the boiling point of the light component is at least 30° C. lower than the boiling point of the heavy component, determined at ambient pressure;
(b) feeding the product mixture into a distillation column via a feed point and subjecting the product mixture to a distillation step, wherein the product mixture is heated to a distillation temperature at a distillation pressure;
(c) feeding a clearing gas at a location below the feed point of the product mixture;
(d) collecting at the top of the distillation column a product gas containing the light component and the clearing gas;
(e) collecting at the bottom of the distillation column a product liquid containing the heavy component,
wherein the product gas obtained in step (d) is directly recycled to a reaction step that produces the product mixture, and
wherein the process operates with one or more of (i) reduced reflux ratio within the distillation column; (ii) reduced energy consumption of the distillation column; and (iii) reduced loss of the heavy component in the product gas, compared to the distillation of the same product mixture in the absence of a clearing gas.
2 . The process according to claim 1 , wherein the product mixture originates from a reaction step selected from a dimethyl ether synthesis reaction, aqueous phase NH 3 synthesis, Fischer-Tropsch synthesis and biomass gasification.
3 . The process according to claim 1 , wherein the light component is selected from CO, CO 2 , ethanol, NH 3 , H 2 and H 2 O and/or the heavy component is selected from di-C 1-4 -ethers, C 1-6 -alkanes, H 2 O and I 2 .
4 . The process according to claim 1 , wherein the clearing gas is selected from argon, helium, CO, N 2 , air, natural gas, water, light hydrocarbons, H 2 and mixtures thereof.
5 . The process according to claim 1 , wherein:
(i) the light component is CO 2 , the heavy component is dimethyl ether; or
(ii) the light component is CO 2 , the heavy component is n-butane; or
(iii) the light component is water, the heavy component is I 2 ; or
(iv) the light component is NH 3 , the heavy component is water.
6 . The process according to claim 5 , wherein the light component is CO 2 , the heavy component is dimethyl ether and the clearing gas is H 2 or CH 4 .
7 . The process according to claim 1 , wherein a binary system of the light component and the heavy component has a Henry's law constant of at least 0.002 mol m −3 Pa −1 .
8 . The process according to claim 1 , wherein the boiling point of the light component is at least 50° C. lower than the boiling point of the heavy component, determined at ambient pressure.
9 . The process according to claim 1 , wherein a binary system of the heavy component and the clearing gas has a Henry's law constant of at most 0.001 mol m −3 Pa −1 , determined at ambient pressure and temperature.
10 . The process according to claim 1 , wherein no flash evaporation step is performed upstream of the distillation column.
11 . The process according to claim 8 , wherein the boiling point of the light component is at least 80° C., lower than the boiling point of the heavy component, determined at ambient pressure.
12 . The process according to claim 1 , wherein the process operates with a reduced reflux ratio, compared to the distillation of the same product mixture in the absence of a clearing gas.
13 . The process according to claim 1 , wherein the process operates with a reduced energy consumption of the distillation column, compared to the distillation of the same product mixture in the absence of a clearing gas.
14 . The process according to claim 1 , wherein the process operates with a reduced reduced loss of the heavy component in the product gas, compared to the distillation of the same product mixture in the absence of a clearing gas.