Regenerating catalytic metal filler bodies used in gas phase cleavage of urethane - by treating at elevated temp. with hydrogen contg. gas

摘要

Process for activating or regenerating the catalytic properties of metal filler bodies for reactors for gas phase cleavage of urethanes, made of steel with an Fe content of at least 50 wt.% or copper bronzes with a Cu content of 60-96 wt.%, comprises treating the filler bodies in a first stage at a temp. of above 200 deg.C. with an oxygen-contg. gas, esp. air, or with hydrogen or a hydrogen-contg. gas mixt., and opt., when an oxygen-contg. gas was used in the first stage, post-treating the filler bodies at a temp. of above 200 deg. with hydrogen or a hydrogen-contg. gas mixt.. USE/ADVANTAGE - The process gives good regeneration of activity of Fe- and Cu-contg. catalysts used in fixed bed catalyst reactors used for gas phase cleavage of urethanes of formula R1 (NHCOOR2)n into the corresp. isocyanates of formula R1(NCO)n and alcohols of formula R2OH, in which R1 = n-valent 1-18C, esp. 6-13C (cyclo)aliphatic hydrocarbon gp. or 6-13C aromatic hydrocarbon gp., R2 = 1-18C, esp. 1-16C aliphatic hydrocarbon gp. or phenyl gp. and n = 1 or 2, esp. 2. The regeneration is technically simple to carry out, can be conducted with the catalyst in situ in the reactor, and does not use corrosive treatments.