P. Meriaudeau et al., ZEOLITE BASED CATALYSTS FOR LINEAR ALKYLBENZENE PRODUCTION - DEHYDROGENATION OF LONG-CHAIN ALKANES AND BENZENE ALKYLATION, Catalysis today, 38(2), 1997, pp. 243-247
Linear alkylbenzenes (LAB) obtained by alkylation of benzene with line
ar C10-14 olefins. In the present work we have investigated the dehydr
ogenation of long chain alkanes over Pt-based catalysts. For convenien
ce n-octane dehydrogenation was used to probe the dehydrogenating prop
erties of the catalysts. The catalysts for dehydrogenation of n-octane
are constituted by Pt or Pt-In alloys supported on alumina, NaY, KL z
eolites and on silicalite. The metal particles were characterized by S
TEM-EDX, H-2 adsorption, and IR of adsorbed CO. The main conclusions a
re: In Pt-In/silicalite system, very small metal particles, less than
1 nm, are formed that are localized in the silicalite pores and Pt is
alloyed with In. These Pr-In particles show unexpected high dehydrogen
ating activity and very high stability against coking even in the abse
nce of added hydrogen. The alkylation of benzene with 1-dodecene over
H-form zeolites was investigated. The reaction temperature was in the
range 373-473 K. Batch reactor was chosen for this study. The results
indicate that dealuminated HY zeolites are apparently the most suitabl
e catalysts. H-ZSM-5, H-ZSM-12 showed almost no activity for the produ
ction of LAB, due to the small size of the channels. The reaction was
influenced considerably by diffusion. While H-mordenite also showed ve
ry low catalytic activity, dealuminated H-mordenite exhibited a signif
icant activity and a very high selectivity for the production of 2-phe
nyldodecane which is the less bulky among the other phenyldodecane iso
mers. The mesoporosity generated within dealuminated mordenite is resp
onsible for these observations.