Effect of acidity on n-octene reaction over potassium modified nanoscale HZSM-5

• Published in: Fuel (Guildford) 2008-12, Vol.87 (17), p.3660-3663
• Main Authors: Long, Huayun, Wang, Xiangsheng, Sun, Wanfu, Xiong, Guang, Wang, Kunyuan
• Format: Article
• Language: English
• Subjects: Acidity; Applied sciences; Crude oil, natural gas and petroleum products; Energy; Exact sciences and technology; Fuels; Modified Hammett indicator; Nanoscale HZSM-5; Pollution caused by production, transportation and treatment of oil and oil shales. Water and soil pollution. Treatments. Pollution control; Potassium; Processing of crude oil and oils from shales and tar sands. Processes. Equipment. Refinery and treatment units
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2008.06.007

The effect of the introduction of potassium into nanoscale HZSM-5 upon acidity and catalytic performance in n-octene reaction was investigated. A modified method of Hammett indicator was used to quantitatively determine the acid strength distribution of the catalysts. The acid sites with acid strength H 0 ⩽ −3.0 (0.20 mmol/g), −3.0 < H 0 ⩽ +2.27 (0.10 mmol/g) and +2.27 < H 0 ⩽ +4.8 (0.80 mmol/g) were detected over the nanoscale HZSM-5. The strong acid sites with acid strength H 0 ⩽ +2.27 were indispensable to the transformation of n-octene into aromatics. Isomerization and cracking of n-octene were apt to take place on the weak acid sites with acid strength +2.27 < H 0 ⩽ +4.8. With decreasing the amount of the strong acid sites, the selectivities to benzene and toluene decreased, while that to C 9+ aromatics increased.