Patent ID: 7053147

Claim:
A process for the manufacture of ethylenically unsaturated acids or esters thereof comprising reacting an alkanoic acid or an ester of an alkanoic acid of the formula R 1 —CH 2 —COOR, where R and R 1 are each, independently, hydrogen, or an alkyl group, with formaldehyde in the presence of a catalyst, wherein the catalyst comprises a porous high surface area silica containing 1–10% by weight of an alkali metal (expressed as metal), wherein the catalyst contains a compound of at least one modifier element selected from magnesium, aluminium, zirconium and/or hafnium in such amount that the catalyst contains a total of 0.25 to 2 gram atoms of said modifier element per 100 moles of silica, and said modifier element compound being dispersed in the pores of said silica.