Preparation and Characterization of γ-Al2O3 with Rich Bronsted Acid Sites and Its Application in the Fluid Catalytic Cracking Process

被引:79
作者
Feng, Rui [1 ]
Liu, Songtao [1 ]
Bai, Peng [1 ]
Qao, Ke [1 ]
Wang, Youhe [1 ]
Al-Megren, Hamid A. [2 ]
Rood, Mark J. [3 ]
Yan, Zifeng [1 ]
机构
[1] China Univ Petr, Key Lab Catalysis, State Key Lab Heavy Oil Proc, Qingdao 266580, Peoples R China
[2] King Abdulaziz City Sci & Technol, Petrochem Res Inst, Riyadh 11434, Saudi Arabia
[3] Univ Illinois, Dept Civil & Environm Engn, Urbana, IL 61801 USA
基金
中国国家自然科学基金;
关键词
SOLID-STATE NMR; FLUORINATED ALUMINA; GAMMA-ALUMINA; GEL METHOD; SURFACE; IDENTIFICATION; HYDROXYFLUORIDES; SPECTROSCOPY; DIFFRACTION; ADSORPTION;
D O I
10.1021/jp411405r
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The objective of this work is to investigate the surface acidity of gamma-Al2O3 after modification and its application in reducing coke formation in the fluid catalytic cracking (FCC) process. gamma-Al2O3 with rich Bronsted acid sites and reduced Lewis acid sites was prepared by the sol gel method using NH4BF4 as a modifier to develop a new functional material to adjust surface acidity. N-2 sorption, powder X-ray diffraction (XRD), Al-27 magic angle spinning nuclear magnetic resonance (Al-27 MAS NMR) spectroscopy, X-ray. photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy were used to characterize the structure and surface properties of the prepared gamma-Al2O3. The results showed that partial fluorination of the surface of gamma-Al2O3 generated small quantities of a pyrochlore-type phase which was formed mainly by substitution of the OH group on six-coordinated aluminum with fluorine. In addition, boron insertion in the structure of gamma-Al2O3 reduced the Lewis acid concentration and increased the surface area of gamma-Al2O3. After aging in an alkaline solution with a F/Al mole ratio of 0.45, the modified gamma-Al2O3 demonstrated high surface area (276 m(2)/g) with gamma alumina structure due to the synergistic effect of boron and fluorine doping by using NH4BF4. However, most importantly the modified gamma-Al2O3 exhibited the high Bronsted/Lewis acid ratio of 0.75. In the bench-scale tests with heavy oil, the modified gamma-Al2O3 showed good catalytic performance by increasing conversion of heavy oil to light oil while reducing coke formation.
引用
收藏
页码:6226 / 6234
页数:9
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