Catalytic Conversion of Linalool on Micro-Mesoporous BEA-Type Zeolite

摘要

The catalytic conversion of the tertiary terpenic alcohol linalool (C_(10)H_(18)O) on samples of the beta type microporous zeolites (BEA-25 and BEA-150 with n(SiO_2)(Al_2O_3) equal to 25 and 150) and on their modified micro-mesoporous forms (RBEA-25 and RBEA-150 with n(SiO_2)(Al_2O_3) equal to 23.8 and 176.4, and transport mesopores with pore diameters 3.5 and 3.8 nm, respectively) was studied. The micro-mesoporous materials were synthesized by recrystallization of initial commercial BEA-zeolites in NaOH aqueous solutions. The chemical composition of the catalysts was determined using X-ray fluorescence analysis. The micro- and mesopores volumes and specific surface areas of catalysts were defined by nitrogen adsorption-desorption. The acid properties of catalysts were estimated using temperature-programmed desorption of ammonia. The catalytic conversion of linalool was carried out in a static system in the liquid phase. The analysis of products of catalytic reactions was carried out by the GC-MS. The reactions of isomerization, dehydration, cyclization and condensation of linalool take place on the studied micro- and micro-mesoporous zeolites by the conversion of linalool in an atmosphere of nitrogen or argon in a liquid phase at 60-170 ℃. The conversion of linalool (4-40%) and the selectivity (45-12 %) of the formation of nerol and geraniol as products of linalool isomerization are low. The introduction of mesopores in the microporous BEA-type zeolite catalysts leads to a significant increase in conversion of linalool and a slight growth in selectivity towards nerol and geraniol. Comparatively high amount of weak acid sites in microporous BEA zeolites contributes to enlarge in selectivity.