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Many petrochemical processes produce light olefin byproducts that can be used to produce propene. This study reports the kinetics of the reactions of ethene, propene and n-butene isomers over a SAPO-34 catalyst at 450 °C and different space velocities and discusses suitable modes of reaction to maximize propene yield. The shape selectivity of SAPO-34 prevented the formation of i-butene and high alkenes. When a single alkene (ethene, propene, or n-butene) was used as the reactant, the other alkenes were rapidly produced by dimerization and cracking such that the final compositions of the light alkenes were close to the equilibrium composition, with propene as the main species. Hydrogen transfer reactions to form an alkane from an alkene were slower than alkene inter-conversion. A kinetic model for alkene inter-conversion was deduced. Experimental and simulation results indicated that a lower partial pressure of the reactant gave increased propene yield when ethene was the feed.

SAPO-34 is an excellent catalyst for the conversion of dimethyl ether (DME) to olefins, but because conventionally synthesized SAPO-34 crystals are too small to be used directly in a fluidized bed, they have to be used as, and have the disadvantages of, a spray-dried catalyst. In this study, SAPO-34 crystals were synthesized in situ to grow on the surface of small α-Al 2 O 3 spheres to produce a zeolite catalyst for a fluidized bed reactor. The influences of the composition of the crystal gel and surface structure of the support were investigated. The catalytic performance of the zeolite crystals grown on the support (surface zeolite) for the conversion of DME to olefins was investigated in a fixed bed microreactor and a fluidized bed reactor. The experiments showed that these surface SAPO-34 crystals gave the same activity and product selectivity as conventionally synthesized free SAPO-34 crystals and a higher reaction rate (normalized to the weight of SAPO-34) than the spray-dried catalyst. In situ synthesis is a simple and effective way to produce a SAPO-34 catalyst for a fluidized bed reactor.