Process for purifying gaseous formaldehyde

Raw gaseous formaldehyde is purified by passing it through a first series of superimposed fluidized beds of solid adsorbent, maintained at 80 DEG -140 DEG C., while continuously circulating solid adsorbent from each bed to the underlying bed and discharging from the lowermost bed the spent adsorbent, delivering the latter to the uppermost bed of a second series of superimposed fluidized beds of solid adsorbent, passing through the latter a stream of inert gas to strip the adsorbed formaldehyde at 130 DEG -150 DEG C., while continuously circulating said spent adsorbent from each bed to the underlying bed and discharging from the lowermost bed the adsorbent thus treated, delivering the latter to the uppermost bed of a third series of fluidized beds of solid adsorbent, and passing through the latter a stream of inert gas to regenerate the adsorbent at 145 DEG -250 DEG C., while continuously circulating the adsorbent from each bed to the underlying bed, discharging the regenerated adsorbent from the lowermost bed and recycling said regenerated adsorbent to the uppermost bed of the first series.