Transformation of et
hylbenzene (EB, 22 wt%)-
m-xylene (78 wt%) mixture was carried out over zeolite MCM-22 catalysts wit
h different acidities. T
he modification of t
he number and strengt
h of t
he acid sites was attained by: (i) dealumination by steaming and successive acid treatment and (ii) isomorp
hous substitution of framework Al for boron ([Al,B]MCM-22). T
he effect of platinum introduction was also investigated. T
he strong decrease in t
he Br酶nsted acidity, concomitant to t
he dealumination procedure, appears unfavorable since it leads to a drastic diminis
h of t
he degree of EB conversion, not compensated by satisfactory level of
m-xylene isomerization. [Al,B]MCM-22 is a modification wit
h muc
h better performance, most probably because it contains bot
h strong, Al-connected acid sites but in lower amount t
han in t
he parent sample, and weaker boron-generated sites and practically no any Lewis sites.
Parent zeolite [Al]MCM-22 as well as B-substitution possess promising properties for ethylbenzene-m-xylene mixture transformation catalyst with adequate degree of EB conversion and extent of p-xylene approach to equilibrium as well as low xylene loss.