The Ionothermal Synthesis And Characterization Of Zinc Phosphates Molecular Sieves

Crystalline porous materials such as zeolites are of interest in a number of areas of modern science, particularly those associated with catalysis, gas storage, ion exchange and so on. The modern industrial application presents us a new challenge with regard to the framework and properties of molecular sieves. It is always international focus to explore new zeolites with new structures. To our knowledge, the different chemistry of the solvents has a notable effect on the structures and properties of the molecular sieves. Ionic liquids or deep eutectic mixtures as the green solvent on the synthesis of the molecular sieves have attracted focus over recent years, due to their special properties such as negligible vapor pressure, high conductivity, product separation, high solubility and so on, as well as plenty of different chemistry component of usable ionic liquids provided more chance for the synthesis of molecular sieves with novel framework. Aiming at preparing molecular sieves with novel framework by ionothermal method, we investigated the possibility and synthetic rule of preparation of zinc phosphate molecular sieves in eutectic mixtures (EU) based on choline chloride-imidazolidone and deep eutectic solvent based on carboxylic acid-quaternary ammonium salts. The synthesized mechanism of ZnPO₄-EUl in HF-ZnO-P₂O₅-choline chloride-imidazolidone system was detailedly investigated.Quaternary ammonium salts may each mixed with oxalic acid to form DESs, all with melting points less than 150℃, making them potenticularly useful solvents for ionothermal synthesis. The typical samples were characterized by XRD, SEM, TG and FT-IR. The main results are listed as follows:Firstly, a three-dimensional zinc phosphate compound with DFT topology, designated as ZnPO₄-EU1, has been synthesized by an ionothermal approach from the system HF-ZnO-P₂O₅-choline chloride-imidazolidone. Ethylenediamine, derived from decomposition of the imidazolidone component of the eutectic mixtures itself, is delivered to the synthesis and serves as an appropriate template for ZnPO₄-EU1.Secondly, the feasibility of the synthesis of zinc phosphate molecular sieves with novel frameworks in the deep eutectic solvent (DES) based on carboxylic acids /quaternary ammonium salts was studied by ionothermal synthesis. Zn₃ (PO₄)₂ (H₂O) could be synthesized in the deep eutectic solvent system P₂O₅-ZnO-quaternary ammonium salts-carboxylic acids. The crystal data : P1 21/c 1 (14), a=8.7052(19)(?),b= 4.8777(11)(?), c=16.6869(4)(?),α=90°,β=95.02(1)°,γ=90°.Thirdly, in the deep eutectic solvent based on oxalic acid-tetrapropyl ammonium bromide system, different organic amines (triethanolamine, ethanolamine, cyclohexylamine, 1, 6-hexanediamine) with low melting point were added into the reaction. A novel zinc phosphate ZnPO₄-DES2 was prepared with the SDA of triethanolamine. It belonged to triclinic system with space group P-1 (2), a=9.992(4)(?),b=12.755(4)(?),c=21.217(4)(?),α=97.7(0)°,β=91.86(0)°,γ=95.35(0)°. While adding ethanolamine, cyclohexylamine and 1, 6-hexanediamine, different zinc phosphates were synthesized.