Coke formation and its effects on shape selective adsorptive and catalytic properties of ferrierite/ZSM-35

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:215008

Xu, W Q; Yin, Y G; Suib, S L ^[1]

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1. Univ. of Connecticut, Storrs, CT (United States); and others

Channels of ferrierite are blocked by carbonaceous deposits (coke) which are formed during butene treatments. The pore blocking inside ferrierite/alumina catalysts affects the yield and selectivity to isobutylene in these reactions. Pore size distribution experiments show that blocking of 10-member ring channels (4.2 x 5.4 {Angstrom}) and 8-member ring channels (3.5 x 4.8 {Angstrom}) of ferrierite by coke reduces the channel size smaller than that of dinitrogen (4.5 {Angstrom}). Thermal desorption data show that ammonia uptake for coked samples of different TOS (time on stream) is decreased from about 62% to 35% of that for the fresh sample. This suggests that channels in coked ferrierites are at least larger than the size of the ammonia molecule (2 {Angstrom}). Uptakes for more bulky molecules such as 1-butene and isobutylene are severely reduced by coke formation (<9% of 1-butene and isobutylene uptakes for the fresh sample). About 76.9% of the coke formed during 18 hr TOS is deposited inside the micropores (<10 {Angstrom}) of ferrierite/alumina. Such coke is aromatic in nature and its hydrogen to carbon ratio decreases with TOS. Three kinds of acid sites were successfully probed with ammonia, 1-butene, and isobutylene. These experiments suggest that adsorption of probe molecules on ferrierite is also a shape selective process.

• OSTI ID: 215008
• Report Number(s): CONF-950801--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
2-METHYLPROPENE
AMMONIA
BUTENES
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTION YIELD
COKE
CONVERSION
DESORPTION
IRON COMPOUNDS
PORE STRUCTURE
SURFACE PROPERTIES
ZEOLITES