Process for dehumidifying moist gas mixtures

1. A process for dehumidifying a moist gas mixture G, in an apparatus (V 1 ), comprising the steps of:

(a) contacting the moist gas mixture G with a liquid absorption medium A VE comprising a mixture of at least one trialkyl phosphate of structure (I):

and at least one salt S selected from the group consisting of Q + A − , Q + (R 1 O) 2 PO 2 − , (Q − ) 2 R 2 OPO 3 2− , and Q + M + R 3 OPO 3 2− ;

wherein the liquid absorption medium A VE at least partially absorbs water from the moist gas mixture G,

to obtain a liquid absorption medium A VE having an elevated water content compared to the liquid absorption medium A VE and a gas mixture G 1 having a relatively low water content compared to the moist gas mixture G,

(b) at least partially removing water from the liquid absorption medium A VE1 to obtain a liquid absorption medium A VE2 having a relatively low water content compared to the liquid absorption medium A VE1 ,

wherein the apparatus (V 1 ) at least partially comprises a surface made of an aluminium material of construction O A1 and, in the apparatus (V 1 ) at least one of the liquid absorption media selected from the group consisting of A VE , A VE1 , A VE2 contacts the surface made of an aluminium material of construction O A1 via at least one contact surface;

wherein:

Q + is a dialkylimidazolium cation;

A − is an anion selected from the group consisting of R*COO − , R′SO 3 − , HSO 4 − , and R″SO 4 ;

R*, R′, R″, R A , R B , R C are each independently of one another an alkyl group;

R 1 , R 2 , R 3 are each independently of one another an alkyl group;

and M + is an alkali metal ion.

2. The process of claim 1 , wherein the gas mixture G is moist air.

3. The process of claim 1 , wherein:

a) Q + is a dialkylimidazolium cation in which the alkyl groups each independently of one another have 1 to 10 carbon atoms;

b) R*, R′, R″, R A , R B , R C , R 1 , R 2 , R 3 are each independently of one another an alkyl group having 1 to 10 carbon atoms; and

c) M + =Li + , K + or Na + .

4. The process of claim 1 , wherein:

a) the salt S is selected from the group consisting of: Q + A − , and Q + (R 1 O) 2 PO 2 − ;

b) Q + is a dialkylimidazolium cation in which the alkyl groups each independently of one another have 1 to 6 carbon atoms;

c) A − is an anion selected from the group consisting of R*COO − , R′SO 3 − , and R″SO 4 − ; and

d) R*, R 1 , R′, R″, R A , R B , R C are each independently of one another an alkyl group having 1 to 6 carbon atoms.

5. The process of claim 1 , wherein R A , R B , and R C are independently of one another either methyl, or ethyl.

6. The process of claim 1 , wherein the liquid absorption medium A VE is an aqueous solution.

7. The process of claim 6 , wherein, in the liquid absorption medium A VE , the total weight of all trialkyl phosphates of structure (I) and all salts S is in the range from 65 wt % to 95 wt % based on the total weight of the aqueous solution.

8. The process of claim 1 , wherein, in the liquid absorption medium A VE , the ratio of the total weight of all trialkyl phosphates of structure (I) to the total weight of all salts S is in the range 1:9999 to 1:9.

9. The process of claim 3 , wherein R A , R B , and R C are independently of one another, either methyl or ethyl.

10. The process of claim 9 , wherein the liquid absorption medium A VE is an aqueous solution, and the total weight of all trialkyl phosphates of structure (I) and all salts S is in the range 65 wt % to 95 wt % based on the total weight of the aqueous solution.

11. The process of claim 10 , wherein, in the liquid absorption medium A VE , the ratio of the total weight of all trialkyl phosphates of structure (I) to the total weight of all salts S is in the range 1:9999 to 1:9.

12. An apparatus (V 2 ) for dehumidifying a moist gas mixture, comprising the components:

(i) a liquid absorption medium A VO comprising a mixture of at least one trialkyl phosphate of structure (I):

and at least one salt S selected from the group consisting of Q + A − , Q + (R 1 O) 2 PO 2 − , (Q + ) 2 R 2 OPO 3 2− , and Q + M + R 3 OPO 3 2− ;

(ii) at least one water absorption unit (W abs2 ) set up for contacting the moist gas mixture with the liquid absorption medium A VO ;

(iii) at least one water desorption unit (W des2 ) which comprises a heat exchanger (W x2 ) and is set up for at least partially removing water from a liquid absorption medium A VO ;

(iv) and a circuit (U 2 ) which connects the water absorption unit (W abs2 ) with the water desorption unit (W des2 ) and by means of which the liquid absorption medium A VO may be circulated;

wherein at least one of the components water absorption unit (W abs2 ), water desorption unit (W des2 ), circuit U 2 at least partially comprises a surface made of an aluminium material of construction O A1 ,

wherein, disposed in the apparatus (V 2 ) is at least one contact surface at which the liquid absorption medium A VO contacts the surface made of an aluminium material of construction O A1 ;

and wherein:

Q + is a dialkylimidazolium cation;

A − is an anion selected from the group consisting of R*COO − , R′SO 3 − , HSO 4 − ,and R″SO 4 − ; and

R*, R′, R″, R A , R B , R C are each independently of one another an alkyl group;

R 1 , R 2 , R 3 are each independently of one another an alkyl group;

M + is an alkali metal ion.

13. The apparatus (V 2 ) of claim 12 , wherein:

a) Q + is a dialkylimidazolium cation in which the alkyl groups each independently of one another have 1 to 10 carbon atoms;

b) R*, R′, R″, R A , R B , R C , R 1 , R 2 , and R 3 are each independently of one another an alkyl group having 1 to 10 carbon atoms; and

c) M + =Li + , K + or Na + .

14. The apparatus (V 2 ) of claim 12 , wherein:

a) the salt S is selected from the group consisting of: Q + A − , and Q + (R 1 O) 2 PO 2 − ;

b) Q + is a dialkylimidazolium cation in which the alkyl groups each independently of one another have 1 to 6 carbon atoms;

c) A − is an anion selected from the group consisting of R*COO − , R′SO 3 − , and R″SO 4 − ; and

d) R*, R 1 , R′, R″, R A , R B , and R C are each independently of one another an alkyl group having 1 to 6 carbon atoms.

15. The apparatus (V 2 ) of claim 12 , wherein R A , R B , and R C are independently of one another either methyl or ethyl.

16. The apparatus V 2 ) of claim 12 , wherein the liquid absorption medium A VO is an aqueous solution.

17. The apparatus (V 2 ) of claim 12 , wherein the liquid absorption medium A VO is an aqueous solution, and the total weight of all trialkyl phosphates of structure (I) and all salts S is in the range from 65 wt % to 95 wt % based on the total weight of the aqueous solution.

18. The apparatus (V 2 ) of claim 12 , wherein in the liquid absorption medium A VO , the ratio of the total weight of all trialkyl phosphates of structure (I) to the total weight of all salts S is in the range 1:9999 to 1:9.

19. The apparatus (V 2 ) of claim 18 , wherein the liquid absorption medium A VO is an aqueous solution, and the total weight of all trialkyl phosphates of structure (I) and all salts S is in the range from 65 wt % to 95 wt % based on the total weight of the aqueous solution.

20. An absorption heat pump, comprising the apparatus (V 2 ) of claim 12 , and further comprising a condenser, an evaporator and a coolant, wherein the coolant is water.