Regeneration of aldehyde decarbonylation catalysts

1. A process for regenerating a catalyst used in the decarbonylation of an aldehyde, wherein the catalyst is a heterogeneous, supported catalyst containing a metal selected from the group consisting of Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt and mixtures thereof, and wherein the catalyst is subjected to a gas stream comprising hydrogen at a temperature of from 200 to 600° C., wherein substantially no oxygen is used in the regeneration process, and wherein the catalyst is not heated in the presence of oxygen before treatment with the gas comprising hydrogen.

2. A process according to claim 1 , wherein the aldehyde is a compound of the following formula:

wherein R1, R2 and R3 are each independently selected from hydrogen, a formyl group, a C1 to C4 hydroxyalkyl group and a C1 to C4 hydrocarbyl group.

3. A process according to claim 2 , wherein R1, R2 or R3, preferably R1, is a formyl group, a hydroxymethyl group or a methyl group and the remaining two substituents selected from R1, R2 and R3 are hydrogen, or wherein all of R1, R2 and R3 are hydrogen, preferably wherein all of R1, R2 and R3 are hydrogen.

4. A process according to claim 3 , wherein the aldehyde is 2,5-diformylfuran, 2-formyl-5-hydroxymethylfuran, 2-formyl-5-methylfuran, 2-formylfuran or a mixture thereof, preferably 2-formylfuran.

5. A process according to claim 1 , wherein the catalyst is regenerated in the absence of the aldehyde.

6. A process according to claim 1 , wherein the catalyst is regenerated at a temperature which is higher than the reaction temperature, preferably at a temperature which is at least 10° C. higher and at most 250° C. higher than the reaction temperature.

7. A process according to claim 1 , wherein the gas stream comprising hydrogen comprises one or more additional gases in a volume ratio of hydrogen to additional gas or gases which is greater than 0.01:1.

8. A process according to claim 1 , wherein the gas stream comprising hydrogen consists of hydrogen.

9. A process according to claim 1 , wherein the metal is selected from the group consisting of Rh, Ir, Pd, Pt and mixtures thereof, preferably from the group consisting of Pd, Pt and a mixture of Pd and Pt.

10. A process according to claim 1 , wherein the catalyst contains one or more additional metals selected from alkali metals and alkaline earth metals.

11. A process according to claim 1 , wherein the support for the catalyst comprises carbon, silica or alumina.