High‐Throughput and Time‐Resolved Energy‐Dispersive X‐Ray Diffraction (EDXRD) Study of the Formation of CAU‐1‐(OH)₂: Microwave and Conventional Heating

Abstract

Aluminium dihydroxyterephthalate [Al(8)(OH)(4)(OCH(3))(8)(BDC(OH)(2))(6)]⋅x H(2)O (denoted CAU-1-(OH)(2)) was synthesized under solvothermal conditions and characterized by X-ray powder diffraction, IR spectroscopy, sorption measurements, as well as thermogravimetric and elemental analysis. CAU-1-(OH)(2) is isoreticular to CAU-1 and its pores are lined with OH groups. It is stable under ambient conditions and in water, and it exhibits permanent porosity and two types of cavities with effective diameters of approximately 1 and 0.45 nm. The crystallization of CAU-1-(OH)(2) was studied by in situ energy-dispersive X-ray diffraction (EDXRD) experiments in the 120-145 °C temperature range. Two heating methods-conventional and microwave-were investigated. The latter leads to shorter induction periods as well as shorter reaction times. Whereas CAU-1-(OH)(2) is formed at all investigated temperatures using conventional heating, it is only observed below 130 °C using microwave heating. The calculation of the activation energy of the crystallization of CAU-1-(OH)(2) exhibits similar values for microwave and conventional synthesis.

Formate modulated solvothermal synthesis of ZIF-8 investigated using time-resolved in situ X-ray diffraction and scanning electron microscopy

“…To obtain kinetic and mechanistic information, EDXRD data recorded during the solvo-/hydrothermal crystallisation of various materials, 20 including some carboxylate-based MOFs, [21][22][23] were most frequently evaluated applying the Avrami-Erofe'ev (abbreviated AE) equation.…”

An in situ investigation of the water-induced phase transformation of UTSA-74 to MOF-74(Zn)

“…Note that after this time a slow intensity decrease in the MOF-74(Zn) powder pattern can be observed, hinting at decomposition of MOF-74(Zn) in [25][26][27][28] Kinetic information on MOF-74(Zn) formation was extracted from the data by applying the model developed by Gualtieri, originally to describe the crystallization kinetics of zeolites 29 but frequently applied to in situ crystallization studies of MOFs. 5,[30][31][32][33][34][35] The model fits the extent of crystallization, in our case MOF-74, as a function of crystallization time t:…”

Chemistry of Metal-organic Frameworks Monitored by Advanced X-ray Diffraction and Scattering Techniques

“…EDXRD experiments for the purposes of crystallization studies were used for several MOF systems: Zr-fumarate, 39 Zr-terephthalate (UiO-66), 40 In-imidazolate, 41 Al-terephthalates (CAU-1), 42,43 Li-tiophenedicarboxylate, 44 MIL-100(Mn) 45 and CPO-27(Co,Ni). 46 Additionally, the crystallization investigation using EDXRD is exampled on the Cu-benzene-1,3,5-tricarbocylate (HKUST-1) under solvothermal conditions.…”