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Structural Evolvement of Heating Treatment of Mg/Al‐LDH and Preparation of Mineral Mesoporous Materials
Author(s) -
Tianhu CHEN,
Huifang XU,
Yifeng WANG,
Chengsong QING,
Mingde FAN,
Gang CHEN
Publication year - 2006
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.2006.tb00226.x
Subject(s) - periclase , mesoporous material , materials science , spinel , chemical engineering , crystallinity , layered double hydroxides , specific surface area , magnesium , oxide , hydrolysis , inorganic chemistry , mineralogy , metallurgy , chemistry , composite material , catalysis , organic chemistry , hydroxide , engineering
Although hydrotalcite, or layered double hydroxides (LDHs), is not a common mineral, it is an important material that can be easily synthesized in laboratory. In this study, structural evolvement and BET surface area changes of heat treated Mg/Al‐LDH is evaluated by XRD, TEM and N 2 ‐BET analyses. The results indicate that the magnesium‐aluminum LDH with carbonate as interlayer anion, periclase‐like oxides was formed at temperatures of 400–800°C. Meanwhile, 2–3 nanometer mesoporous were formed during decomposition of LDH. However, the heat treated samples still preserve the morphology of the original LDH plates. Periclase‐like formed from LDH heat treatment may re‐hydrolyze and recover the structure of LDH. However, crystallinity of the recovered LDH is lower than that of the original LDH. This heat treatment will result in formation of (Mg, Al)‐oxide nano‐crystals and nanopores among the nano‐crystals. When heating temperature exceeds 1000, the periclase‐like (Mg, Al)‐oxide is transformed into a composite with periclase (MgO) and spinel phases. The periclase can be re‐hydrolyzed and dissolved in HCI solution. After acid treatment, the sample with a high surface area is composed of spinel nano‐crystals and nanopores among them. Our results will provide a new and economic way to synthesize mesoporous materials through pathways of phase transformation of precursor materials with different composition.