OLIGOMERIZATION OF C4 OLEFINS OVER SURFACE- MODIFIED ZEOLITES ZSM-5 AND BETA
The effect of modification of zeolites ZSM-5 and Beta by tetraethoxysilane (TEOS) on the activity and selectivity of catalyst in the butene oligomerzization reaction was stud- ied. Surface modified catalysts were synthesized by im- pregnation of TEOS and subsequent calcination at 550°С and 620°С. The physical and chemical properties of the catalysts were characterized by XRD, DTA analysis, UV- spectra of Hammet indicators and nitrogen adsorption- desorption methods. Oligimerization products were ana- lyzed using GC and GCMS data combination. It has been demonstrated that the modification procedure at a calcina- tion temperature of 550°С significantly increases the selec- tivity of target olefinic products in 2-5 times and decreases the coke content by 33-45%. A formation of the SiO2 phase in the cubic modofication was observed for zeolite Beta treated at 620°С. However, this did not increase the selectivity of target products.