pH摆动法制备无定形硅铝材料及性能研究

摘要/Abstract

摘要： 无定形硅铝具有一定的酸性和较大的孔径，常用于加氢裂化、催化裂化等催化剂中。采用pH摆动法制备了不同SiO₂含量的无定形硅铝，采用透射电子显微镜、X射线衍射、N₂吸附-脱附、吡啶吸附红外光谱和固体核磁共振波谱等技术对样品的物化性质进行了表征。结果表明，随着SiO₂质量分数从9.4%增加到39.1%，无定形硅铝的比表面积从443 m²/g降低到367 m²/g，四配位铝比例从29.2%增加到42.0%，Bronsted酸酸量（200℃脱附温度）从7.8 μmol/g增加到34.8 μmol/g。进一步对制备的样品进行水热处理，发现随着水热处理温度的升高，无定形硅铝的比表面积逐渐降低，Bronsted酸酸量逐渐增加。将制备的无定形硅铝用于聚乙烯塑料裂解反应中，结果发现，无定形硅铝的Bronsted酸酸量越大，塑料热裂解温度越低，裂化活性越高。

关键词: 无定形硅铝, pH摆动法, 水热处理, 孔结构, 酸性, 塑料裂解

Abstract: Amorphous silica-alumina (ASA) is characterized by moderate acidity and large pore sizes, and is commonly used in catalysts for processes such as hydrocracking and catalytic cracking. In this study, ASA with varying SiO₂ compositions was prepared using the pH-swing method. The physicochemical properties of the samples were characterized using techniques such as TEM, XRD, N₂ adsorption-desorption, pyridine adsorption-IR spectroscopy, and solid-state NMR.The results indicate that as the SiO₂ mass fraction increased from 9.4% to 39.1%, the specific surface area of ASA decreased from 443 m²/g to 367 m²/g, the proportion of tetra-coordinated aluminum increased from 29.2% to 42.0%, and the content of Bronsted acid sites (at a desorption temperature of 200°C) increased from 7.8 μmol/g to 34.8 μmol/g. Further hydrothermal treatment of the samples revealed that as the hydrothermal temperature increased, the specific surface area of ASA gradually decreased, while the Bronsted acid number gradually increased. When the prepared ASA was used in the pyrolysis reaction of PE plastic, a higher Bronsted acid number of ASA resulted in a lower plastic pyrolysis temperature and higher cracking activity.

Key words: amorphous silica-alumina, pH-swing method, hydrothermal treatment, pore structure, acidity, plastic pyrolysis

鲍俊聂红杨清河曾双亲桑小义. pH摆动法制备无定形硅铝材料及性能研究[J]. 石油炼制与化工, 2026, 57(8): 1-8.

参考文献

[1]Busca G.Catalytic materials based on silica and alumina: Structural features and generation of surface acidity[J].[J].Progress in Materials Science, 2019, 104:215-249
[2]Narula C K, Rokosz M, Allard L F, et al.Sol-Gel processed silica-alumina materials for diesel engine emission reduction catalysts[J].Langmuir, 2000, 16(8):3818-3822
[3]宋国良，肖寒，柏洪浩，等.分子筛与无定形硅铝的比例对柴油加氢裂化催化剂性能的影响[J].石油炼制与化工, 2021, 52(02):39-45
[4]师希娥，张晔，戴立益，等.无定形硅铝和-催化裂化性能的比较研究[J].化学学报, 2003, 61(9):1388-1392
[5]Xu B, Sievers C, Lercher J A, et al.Strong Br?nsted acidity in amorphous silica-aluminas[J].The Journal of Physical Chemistry C, 2007, 111(32):12075-12079
[6]Serp P, Kalck P, Feurer R.Chemical vapor deposition methods for the controlled preparation of supported catalytic materials[J].Chemical Reviews, 2002, 102(9):3085-3128
[7]Wang Z, Jiang Y, Baiker A, et al.Efficient acid-catalyzed conversion of phenylglyoxal to mandelates on flame-derived silicaalumina[J].ACS Catalysis, 2013, 3(7):1573-1577
[8]Yabuki M, Takahashi R, Sato S, et al.Silica-alumina catalysts prepared in sol-gel process of TEOS with organic additives[J].Physical Chemistry Chemical Physics, 2002, 4(19):4830-4837
[9]Li T, Zhang L, Tao Z, et al.Synthesis and characterization of amorphous silica-alumina with enhanced acidity and its application in hydro-isomerization/cracking[J]. Fuel, 2020, 279: 118487.
[10]Xu B, Yang Y, Xu Y, et al.Synthesis and characterization of mesoporous Si-modified alumina with high thermal stability[J]. Microporous and Mesoporous Materials, 2017, 238: 84-89.
[11]Katada N, Toyama T, Niwa M.Mechanism of growth of silica monolayer and generation of acidity by chemical vapor deposition of tetramethoxysilane on alumina[J].The Journal of Physical Chemistry, 1994, 98(31):7647-7652
[12]Katada N, Fukui H, Niwa M.A continuous-flow method for chemical vapor deposition of tetramethoxysilane on γ-Alumina to prepare silica monolayer solid acid catalyst[J].Journal of Chemical Engineering of Japan, 2001, 34(3):306-311
[13]Li T, Tao Z, Zhang L, et al.Facile and cost-effective synthesis of acidity-enhanced amorphous silica-alumina for high-performance isomerization[J]. Journal of Solid State Chemistry, 2021, 300: 122249.
[14]Xu J, Wang R, Zhang Y, et al.Identification of the structure of Ni active sites for ethylene oligomerization on an amorphous silica-alumina supported nickel catalyst[J].Chinese Journal of Catalysis, 2021, 42(12):2181-2188
[15]Suganuma S, Arita K, Nakano F, et al.Adsorption kinetics in removal of basic nitrogen-containing compounds from practical heavy oils by amorphous silica-alumina[J]. Fuel, 2020, 266: 117055.
[16]Bao J, Yang Q, Zeng S, et al.Synthesis of amorphous silica-alumina with enhanced specific surface area and acidity by pH-swing method and its catalytic activity in cumene cracking[J]. Microporous and Mesoporous Materials, 2022, 337: 111897.
[17]Feng R, Bai P, Liu S, et al.The application of mesoporous alumina with rich Br?nsted acidic sites in FCC catalysts[J]. Applied Petrochemical Research, 2014, 4:367-372.
[18]Khanna A, Bhat D.Nanocrystalline gamma alumina coatings by inverted cylindrical magnetron sputtering[J]. Surface and Coatings Technology, 2006, 201: 168-173.
[19]Kang M, Yoon D.Effects of surface hydroxyl ions on the color of sintered Al2O3 characterized by X-ray photoelectron and infrared spectroscopy[J].Journal of the European Ceramic Society, 2022, 42(16):7508-7515
[20]Chizallet C, Raybaud P.Pseudo-bridging silanols as versatile bronsted acid sites of amorphous aluminosilicate surfaces[J]. Angewandte Chemie International Edition in English. 2009, 48: 2891-2893.
[21]Wang Z, Jiang Y, Jin F, et al.Strongly enhanced acidity and activity of amorphous silica-alumina by formation of pentacoordinated AlV species[J]. Journal of?Catalysis, 2019, 372: 1-7.