Ionic liquids and eutectic mixtures as solvent and template in synthesis of zeolite analogues

Abstract

The challenges associated with synthesizing porous materials mean that new classes of zeolites (zeotypes)-such as aluminosilicate zeolites and zeolite analogues-together with new methods of preparing known zeotypes, continue to be of great importance. Normally these materials are prepared hydrothermally with water as the solvent in a sealed autoclave under autogenous pressure. The reaction mixture usually includes an organic template or 'structure-directing agent' that guides the synthesis pathway towards particular structures. Here we report the preparation of aluminophosphate zeolite analogues by using ionic liquids and eutectic mixtures. An imidazolium-based ionic liquid acts as both solvent and template, leading to four zeotype frameworks under different experimental conditions. The structural characteristics of the materials can be traced back to the solvent chemistry used. Because of the vanishingly low vapour pressure of ionic liquids, synthesis takes place at ambient pressure, eliminating safety concerns associated with high hydrothermal pressures. The ionic liquid can also be recycled for further use. A choline chloride/urea eutectic mixture is also used in the preparation of a new zeotype framework.

Role of boron-containing ionic liquid in the synthesis of manganese borophosphate with extra-large 16-ring pore openings

“…It brings more opportunities to synthesize new compounds [16,17]. Moreover, the ionothermal condition tends to generate interrupted structures, which may be helpful to the formation of extra-large pore openings.…”

Selective anion exchange with nanogated isoreticular positive metal-organic frameworks

“…Here we are particularly interested in the separation of organic anions. Among reported MOFs, there are comparatively few permanently porous MOFs with positive framework (P-MOFs) 6,36,37 , whose rarity is also mirrored in other types of porous materials, including zeolites [38][39][40][41][42][43][44][45] . In addition, known P-MOFs often have low stability or small pore size that only permits the exchange of small inorganic anions 7,10 .…”

Low melting mixtures in organic synthesis – an alternative to ionic liquids?

“…22 The solubility was 50-to 100-fold higher in glucose/fructose or aconitic acid/ ChCl mixtures than in water. 22 Deep eutectic solvents are also versatile tools for the synthesis of inorganic materials and play a structure directing role as templates for the framework formation of metal phosphates, 85 oxalatophosphates, 86 aluminophosphates, 87 carboxymethylphosphonates, 88 oxalatophosphonates, 89 polyoxometalate-based hybrids, 90 zeolites, 91 or metal-organic frameworks. 92 Their structure directing role was also observed for nucleic acids which can form several secondary structures that reversibly denature on heating in a water-free DES.…”