Kinetic analysis of isobutane/butene alkylation over ultrastable H-Y zeolite

Journal Article · Fri Nov 01 04:00:00 EST 1996 · Industrial and Engineering Chemistry Research

DOI:https://doi.org/10.1021/ie960172y· OSTI ID:404541

Simpson, M F; Wei, J; Sundaresan, S ^[1]

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1. Princeton Univ., NJ (United States). Dept. of Chemical Engineering

The alkylation of isobutane with trans-2-butene over ultrastable Y-type zeolites has been studied. It is well-known that this reaction is accompanied by a rapid deactivation of the catalyst. The objective of this study is to elucidate the route to catalyst deactivation so that the means of mitigating this problem can be identified. Using the initial reaction rate data, evidence has been found for a Broensted acid mechanism. Under liquid-phase conditions, the reaction has been found to be severely diffusion limited. Using a kinetic model that accounts for the effect of diffusion, it was found that alkylation over this catalyst suffers from slow hydride transfer relative to olefin addition. This gives rise to a rapid formation of C{sub 12}{sup +} carbocations. The formation of these cations has been tied to catalyst deactivation, using a mathematical model for the reaction. On the basis of the insight gained from the experiments and modeling work, optimal reactor and catalyst design issues are examined. It is inferred from the reaction mechanism and confirmed experimentally that alkylation under pulsed flow conditions yields higher trimethylpentane/dimethylhexane ratios and slower rates of deactivation. It is suggested that the cause of the slow rate of hydride transfer is steric hindrance. Strategies for relieving this steric hindrance are proposed.

• OSTI ID: 404541
• Journal Information: Industrial and Engineering Chemistry Research, Journal Name: Industrial and Engineering Chemistry Research Journal Issue: 11 Vol. 35; ISSN IECRED; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
10 SYNTHETIC FUELS
2-METHYLPROPANE
ALKYLATION
BUTENES
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
DEACTIVATION
FUEL ADDITIVES
GASOLINE
HYDROGEN TRANSFER
ZEOLITES