Abstract: Process for preparing shaped base materials for use in solid catalysts for commercial processes. The solid contact material is prepared by pre-soaking a porous solid particulate carrier material in an organic liquid, immersing the carrier without drying in a dilute acid solution for a given time interval, washing, drying and calcining the impregnated carrier. After calcination, the carrier is impregnated with an active material.

Abstract: A sulfur dioxide containing gas stream is passed through a gas scrubber through which is circulated a scrubbing medium, preferably slurried, containing a reactant which reacts with the sulfur dioxide to produce sulfites and/or sulfates, a portion of which precipitate. At least a portion of the precipitated sulfites and/or sulfates are removed from the scrubbing medium which is rejuvenated with fresh reactant to maintain substantially steady state conditions in the scrubber. To minimize scaling in the scrubbing system, seed crystals of the sulfites and/or sulfates are introduced into the scrubbing medium, the seed crystals being in number and size so as to control the level of supersaturation of the scrubbing medium with respect to the sulfites and/or sulfates.