processes for the regeneration of a silica-supported depleted alkali metal catalyst and for the preparation of an ethylenically unsaturated acid or ester and re-impregnated catalyst

摘要

1/1 summary â € œprocesses for the regeneration of a silica-supported depleted alkali metal catalyst and for the preparation of an ethylenically unsaturated acid or ester, and a re-impregnated catalystâ € a process for the regeneration of a silica supported depleted alkali metal catalyst is described. The alkali metal level on the spent catalyst is at least 0.5 mol% and the silica support is a zero gel. The process comprises the steps of contacting the silica-supported depleted alkali metal catalyst with a solution of an alkali metal salt in a solvent system that has a polar organic solvent as the major component. . a re-impregnated catalyst prepared by the process of the invention comprising any silica zero-gel support and a catalytic metal selected from an alkali metal in the range of 0.5 to 5 mole% over the catalyst, wherein the surface area of the silica bracket 180m / g is also described. The invention is applicable to a process for the preparation of an ethylenically unsaturated acid or ester comprising contacting an ester or alkanoic acid of a formula. -ch-coor, with formaldehyde or a suitable source of formaldehyde.