SKELETAL ISOMERIZATION OF N-BUTENE ON PHOSPHORUS-CONTAINING CATALYSTS

Catalysts containing phosphorus, oxygen, silicon and - eventually - al so aluminium, can be active in skeletal isomerisation of n-butene. The condition of activity is the presence of OH groups of the moderate ac idity. The presence of strong Bronsted sites is undesired since these are expected to be responsible for by-product formation. No role of Le wis sites was observed with these catalysts. Low stability of 'open su rface' catalysts is caused by poisoning of active sites by carbonaceou s layers. Deactivation can be suppressed by placing the active site in a confined space and a zeolitic channel with 10-membered rings fulfil s such a condition.