Effect of coke formation on the transformations of butylenes on a high-silica zeolite catalyst

The transformations of butylenes on a high-silica zeolite catalyst (HHSZC) at 423–773 K were studied. Liquid reaction products formed above 443 K. The liquid phase of the reaction products mainly consisted of aliphatic hydrocarbons at 448–523 K and aromatic hydrocarbons at 623–723 K. The catalyst activity in the formation of liquid products did not show itself until 4–6% consolidation products (CPs) accumulated on its surface. DTA and gravimetric studies showed that CPs were nonuniform in composition. Some of the CPs were removed by decomposition under nitrogen, while others by oxidation with oxygen. It was inferred from ammonia adsorption data that the accumulation of CPs on the surface of HHSZC led to a decrease in the number of acid centers.