Process and catalyst for preparing 1,4-butanediol

1. A process for preparing 1,4-butanediol by hydrogenating 2-butyne-1,4-diol or 4-hydroxybutanal, said method comprising contacting an aqueous solution comprising 2-butyne-1,4-diol or 4-hydroxybutanal with hydrogen and an activated nickel catalyst, wherein said activated nickel catalyst comprises:

a) a porous foam structure;

b) macroscopic pores in the range of 100 to 5000 μm;

c) a bulk density of not more than 0.8 kg/L.

2. The process of claim 1 , wherein the hydrogenation of 4-hydroxybutanal is carried out at a hydrogen pressure in the range of 10 to 110 bar.

3. The process of claim 2 , wherein the hydrogenation is carried out in a temperature range of 50 to 200° C.

4. The process of claim 1 , wherein the hydrogenation of 2-butyne-1,4-diol is carried out at a hydrogen pressure in the range of 50 to 350 bar and a temperature range of 50 to 150° C.

5. The process of claim 1 , wherein said process is carried out in a fixed bed reactor.

6. The process of claim 5 , wherein the fixed bed reactor is operated adiabatically, with a temperature at the reactor inlet in the range of 80 to 100° C. and a temperature at the reactor outlet in the range of 110 to 150° C.

7. The process of claim 6 , wherein the activated nickel catalyst has an aluminum content of not more than 15% by weight.

8. The process of claim 7 , wherein the activated nickel catalyst comprises macroscopic pores with sizes in the range of 200 to 2500 μm.

9. The process of claim 5 , wherein the process is carried out continuously in a trickle bed reactor, liquid-filled reactor, or a bubble column.

10. The method of claim 5 , wherein the fixed bed reactor is operated in a “once through” mode, in which the reactants are introduced into the reactor and the product mixture is removed after the reaction.

11. The process of claim 1 , wherein the activated nickel catalyst comprises 0 to 10% by weight of at least one of the elements selected from the group consisting of: molybdenum, iron, and chromium.

12. The process of claim 11 , wherein the hydrogenation is carried out continuously.

13. The process of claim 12 , wherein the activated nickel catalyst has an aluminum content of not more than 15% by weight.

14. The process of claim 13 , wherein the activated nickel catalyst has a porous foam structure, wherein the macroscopic pores have sizes in the range of 200 to 2500 μm.

15. The process of claim 1 , wherein the hydrogenation is carried out batchwise in a stirred tank reactor using a two temperature reaction regime, wherein:

a) the temperature in the stirred tank at the start of the reaction is maintained in the range of 90 to 105° C. so that 2-butyne-1,4-diol is reacted with hydrogen to give 2-butene-1,4-diol;

b) after uptake of hydrogen stoichiometrically equivalent to the amount of 2-butyne-1,4-diol used, the first reaction stage is concluded and the temperature in the stirred tank is then increased to 130 to 135° C. and maintained in that range until completion of the hydrogenation to give 1,4-butanediol.

16. The process of claim 15 , wherein the catalyst is arranged in a holding device close to the stirrer shaft such that a flow of the reaction mixture through the catalyst bed is generated by the stirrer.

17. The process of claim 15 , wherein the hydrogenation of butyne-1,4-diol is carried out at a hydrogen pressure in the range of 50 to 350 bar.

18. The process of claim 17 , wherein the activated nickel catalyst has an aluminum content of not more than 15% by weight.

19. The process of claim 15 , wherein the activated nickel catalyst comprises macroscopic pores with sizes in the range of 200 to 2500 μm.

20. The process of claim 15 , wherein the activated nickel catalyst comprises 0 to 10% by weight of at least one of the elements selected from the group consisting of: molybdenum, iron, and chromium.