화학공학소재연구정보센터
Industrial & Engineering Chemistry Research, Vol.57, No.23, 7783-7794, 2018
Effect of Next-Nearest-Neighbor Aluminum Atoms in the HZSM-5 Framework Synthesized with Various Aluminum Sources on Liquefied Petroleum Gas Transformation to Light Olefins
HZSM-5 catalysts with various aluminum distributions in their frameworks and different Si/Alger ratios were synthesized to investigate the product distribution in liquefied petroleum gas cracking. The characterization of synthesized zeolites was performed by X-ray diffraction (XRD), Brunauer, Emmett, and Teller (BET) method, (scanning electron microscopy) SEM, NH3-TPD, X-ray fluorescence (XRF), and direct reflectance (DR) UV-visible, and Al-27 MAS NMR analyses. The maximum proportion of ONNN aluminum atoms (90.6-92.6%) were found in HZSM-5 synthesized with aluminum nitrate. The higher ONNN aluminum atoms in the zeolite framework and lower content of aluminum at channel intersections enhanced the olefin yield and decreased the C-5(+) yield. The amount of coke increased with increase of the 1NNN AI atoms. The optimum olefin yields for HZSM-5 synthesized with aluminum nitrate, aluminum chloride and aluminum hydroxide were found to be 47.22% with Si/Al-gel 50, 45.47% with Si/Al-gel 30, and 44.32% with Si/Al-gel 30, respectively. The propylene to ethylene ratio and catalytic stability increased with decrease of the acid strength distribution.