Patent ID: 7507855

Claim:
A process for the production of a C 2 -C 4 aliphatic carboxylic acid and/or the corresponding ester, by carbonylating the corresponding C 1 -C 3 aliphatic alcohol and/or an ester derivative thereof with carbon monoxide in the presence of a catalyst comprising a zeolite having at least one 8-member ring channel, said 8-member ring channel being interconnected with a channel defined by a ring with greater than or equal to 8 members, said 8-member ring having a window size of at least 2.5 Angstroms×at least 3.6 Angstroms and at least one Brønsted acid site and which zeolite has a silica:X 2 O 3 molar ratio of at least 5, wherein X is selected from aluminium, boron, iron, gallium and mixtures thereof with the proviso that the zeolite is not mordenite or ferrierite.