Crystalline silicate catalysts with deactivated outer surface - have pores blocked before contact with deactivation agent

摘要

Some or all the catalytically active sites on the external surfaces of crystalline aluminosilicate and/or borosilicate catalyst are deactivated by (a) making the pores inaccessible to deactivating agent; and (b) subsequently contacting with deactivating agent. Pref., the pores are made inaccessible by saturating the pore vol. of the silicate with an organic component which cannot mix with or dissolve in the deactivating agent, pref. an aromatic or alkylaromatic hydrocarbon, esp. toluene. The deactivating agent is pref. a soln. of alkali metal salt, esp. Na salt, in water, and contact is at 0-200 deg. C for at least 1/2 hr. The modified silicate so prepd. is claimed. A crystalline silicate having different catalytic properties on its external surface from the pore surfaces has (part of) the catalytically active sites on the external surface replaced by catalytically inactive alkali metal ions, esp. Na ions. The catalysts are useful in e.g. hydrocarbon conversions. Inactivation of external surfaces reduces pore blocking, giving a catalyst of increased life and selectivity.