AUTHOR=Wu Zhiqiang , Jiang Longwen , Dong Quan , Gao Qiang , Cai Jingxuan , Cheng Xiaowei 

TITLE=Effect and mechanism of rare Earth and alkaline Earth metals on the high-temperature stability of activated alumina

JOURNAL=Frontiers in Materials

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2023.1103590

DOI=10.3389/fmats.2023.1103590

ISSN=2296-8016

ABSTRACT=<p>Active alumina (Al<sub>2</sub>O<sub>3</sub>) is one of the carrier materials used for the purification of automobile exhaust. The crystal transformation of active Al<sub>2</sub>O<sub>3</sub> is due to the high temperature of the automobile exhaust port, which greatly reduces the specific surface area and affects the catalytic efficiency. To improve the high-temperature stability of active Al<sub>2</sub>O<sub>3</sub>, this study synthesized Al<sub>2</sub>O<sub>3</sub><italic>via</italic> the gel-sol method. The influence of rare Earth and alkaline Earth metal doping modification on the high-temperature stability of activated Al<sub>2</sub>O<sub>3</sub> was investigated. The specific surface areas were analyzed using Brunauer–Emmett–Teller, X-ray diffraction, Fourier-transform infrared spectroscopy, Scanning electron microscopy, and transmission electron microscopy to explore the effects and mechanism of different contents of La, Ce, and Ba on active Al<sub>2</sub>O<sub>3</sub>. The results showed that suitable single doping of La, Ce, and Ba inhibited the phase transition of Al<sub>2</sub>O<sub>3</sub> and improved the high-temperature stability of active Al<sub>2</sub>O<sub>3</sub>. When 1% of La and Ba were mixed and doped into active Al<sub>2</sub>O<sub>3</sub>, the specific surface area of the sample after aging at 1,100°C for 4 h was 119.2512 m<sup>2</sup>/g. X-ray diffraction analysis revealed the agglomeration of Ba atoms inside the alumina and that the incorporated La atoms accelerated the agglomeration and promoted the formation of BaAl<sub>2</sub>O<sub>4</sub>.</p>