Light Alkene Selectivity on Y Zeolite FCC Catalysts

M.C. GALIANO; U. SEDRAN

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

AMER CHEMICAL SOC

Lugar: Washington; Año: 1997 vol. 36 p. 4207 - 4211

0888-5885

n-Hexadecane was used as a test reactant with a pulse technique over various types of commercialFCC catalysts, either equilibrated or steam-dealuminated, to study the changes in the selectivityto light C4-C6 alkenes over unit cell sizes ranging from 24.26 to 24.56 Å at 475-525 °C. Theactivity depended on the total catalyst acidity, while the unit cell size of the zeolite componentwas the factor controlling the relative alkene yields. Inside a given hydrocarbon group, alkenesdecreased their relative yields when conversion increased, while for a given conversion, theirconsumption as a function of increasing unit cell sizes was dependent on the molecular size:the higher the molecular weight, the slower the depletion. Linear alkenes showed a steadyrate of change along the whole range of unit cell sizes, while branched alkenes showed a muchfaster consumption when unit cell sizes were under about 24.31 Å. The yield of light alkeneswas significantly augmented as a function of increasing temperature, linear alkenes beingfavored. The incidence of hydrogen-transfer reactions is discussed.