New Insights into the Role of Amines in the Synthesis of Molecular Sieves in Ionic Liquids

Abstract

A combination of state-of-the art in situ one- and two-dimensional NMR spectroscopy and density functional theory (DFT) calculations have been employed for the first time to investigate the role of amines in the synthesis of aluminophosphate molecular sieves in ionic liquids (ILs). In situ rotating-frame nuclear Overhauser effect spectroscopy (ROESY) was used to demonstrate that the hybrid of imidazolium ionic liquids with organic amines, such as morpholine, connected through a hydrogen bond can be formed in the gel during the crystallization of molecular sieves. By combining the characterizations of the final solid products obtained by using XRD analyses, solid-state NMR spectroscopy, thermogravimetric analysis, and DFT calculation results, it was verified that the hybrid between morpholine and the imidazolium cation in the initial preparation stage can act as the structure-directing agent (SDA) for the synthesis of AFI-structured aluminophosphate molecular sieves. Our findings may suggest a synthesis mechanism of molecular sieves in ionic liquids in which the IL-organic amine hybrid is required in the nucleation step, whereas the crystal growth occurs through the occlusion of ionic liquids in the zeolite channels.

Varied forms of lamellar [Sn3Se7]n2n−anion: the competitive and synergistic structure-directing effects of metal–amine complex and imidazolium cations

“…For instance, research from our own and Dehnen's groups showed that a combination of ILs and an organic amine as auxiliary solvent was an efficient system for the fabrication of selenidostannates, in which the organic amine and the IL cations might co-induce specific structures. 24,25 Similar phenomena have been observed in the ionothermal syntheses of zeolites; [26][27][28][29] for example, a new open-framework aluminophosphate with a unique Al/P ratio was synthesized by using an amine and ILs as co-templates. 26, 29 Thus we realize that syntheses in ILs with different SDAs would produce highly novel structures due to the chemical and compositional flexibility of SDAs.…”

Kinetics of enzymatic synthesis of monoferuloyl glycerol and diferuloyl glycerol by transesterification in [BMIM]PF6

“…However, in the previous enzymatic synthesis of FGs, excess glycerol or organic solvents were required as reactants and solvents to obtain high FGs yields [9,13,15,16]. To overcome these disadvantages, ionic liquids (ILs), due to their negligible vapor pressure, high thermal stability for enzyme, and favorable solvating property (molecular sieve role) for particular components [17][18][19][20][21], have been used as an alternative green reaction medium for many enzymatic reactions. Previously, we developed a novel IL ([EMIM]TF 2 N) system for lipase-catalyzed DFG production with ∼100% EF conversion and 45% DFG yield [11].…”

Probing ZnAPO-34 Self-Assembly Using Simultaneous Multiple in Situ Techniques

“…Under nonhydrothermal conditions, this question becomes even more pertinent. [9][10][11][12] To date, a number of in situ crystallization studies probing microporous aluminophosphate synthesis exist, the majority of which focus on (Co)APO-5 (AFI structure). These studies utilize mostly scattering methods for probing the onset of crystallization, although many also employ spectroscopic techniques allowing for atomic/molecular insight into the self-assembly process.…”