Rapid and One‐Step Transformation of LiAlH₄ to Inorganic and Organic Anion Intercalated Li‐Al Layered Double Hydroxides

Abstract

Monoclinic [LiAl2(OH)6]OH·2H2O was formed by the hydrolysis of LiAlH4 within few minutes of irradiation with microwaves as confirmed by powder X‐ray diffraction (PXRD), infrared, Raman, 27Al NMR spectroscopic, and thermal analysis experiments. The flaky morphology of crystallites was evident in microscopy images. The compound is mesoporous with surface area of 50 m2/g. When required amounts of corresponding mineral acids were added during the hydrolysis of LiAlH4, exchange of the interlayer hydroxide ion with nitrate and chloride ions was successful. This was verified by the hexagonal symmetry observed in the PXRD patterns together with the evidence gathered from infrared, 27Al NMR spectra, thermal analyses, and the substantial changes in ligand to metal charge‐transfer bands in their UV/Visible spectra. A host of Li‐Al LDH compounds intercalated with aliphatic dicarboxylate (oxalic, malonic, succinic, glutaric, adipic, and sebacic acid) anions were rapidly produced when a mixture of LiAlH4 and the respective acid was irradiated with microwaves for a few minutes. The basal spacing of the dicarboxylate anion intercalated systems increased linearly with the increase in the number of –CH2‐ groups in them. Microwave assisted reaction of ethylene glycol with [LiAl2(OH)6]OH·2H2O resulted in its intercalation.

Hydrolysis Kinetics of LiAlH4 at Subzero Temperatures

“…The KOH·H 2 O (JCPDS 36–0791) was observed to dominate in the dried hydrolysis solid products from LiAlH 4 in either 27.1 wt% KOH (Figure , black) or a 27.1 wt% KOH–30.0% ethylene glycol aqueous solution (Figure , red) at −40 °C due to the extra amount of KOH and decomposition of K­[Al­(OH) 4 ]. The XRD features of LiAl 2 (OH) 7 ·2H 2 O were observed after washing the solid hydrolysis products with deionized water (Figure , blue), which is consistent with the direct hydrolysis products in water, indicating no consumption of either KOH or ethylene glycol.…”

Recent Progress in Two‐Dimensional Layered Double Hydroxides and Their Derivatives for Supercapacitors

“…[11] The 2D hydroxide layer consists of octahedronss harings ix edges, with infinite extension of the ab plane of crystallography.M ore than two types of metal cations can be incorporated into the host layers to compound as inglem aterial. [12] In addition, M + and M 4 + ions can also be introduced to extendt he range of LDHs, such as LiAl LDH [13] and NiTiL DH. [14] There are several processing techniques that have been developed to synthesize LDHs for applications in SCs, such as hydrothermal, [15] electrodeposition, [16] chemical exfoliation and self-assembly, [17] and templating methods.…”

“…More than two types of metal cations can be incorporated into the host layers to compound a single material . In addition, M + and M 4+ ions can also be introduced to extend the range of LDHs, such as LiAl LDH and NiTi LDH …”

Preparation of Ca/Al-Layered Double Hydroxides/Biochar Composite with High Adsorption Capacity and Selectivity toward Cationic Dyes in Aqueous

“…Dyes have high solubility in water that is difficult to remove by conventional methods [1]. Dyes are used in various industries, such as: adsorption, coagulation / flocculation, photocatalytic decolorization, microbial decomposition, and electrochemical methods [4][5][6][7].…”