Research Progress of Materials Used for Elemental Halogen Capture

Abstract

Elemental halogen, that is fluorine (F2), chlorine (Cl2), bromine (Br2) and iodine (I2), plays an important role in the chemical industry. However, the toxicity, corrosiveness and volatility of elemental halogen pose serious challenges for their safe storage and transportation. Thus, the precuring of these elemental halogen can effectively improve the safety of their usage. Ideal precuring materials for elemental halogen need to meet a variety of requirements, such as stability, selectivity, recyclability, processability, etc., which brings great challenges to the design and synthesis of desired materials. So far, some precuring materials for Cl2 and Br2 have been reported (F2 is not available yet). The summary and review of these materials will help to provide reference for the follow-up materials optimization and design. However, as far as we know, the related review has not been reported yet. Therefore, we give a comprehensive overview of the precuring materials for Cl2 and Br2 including porous organic polymers (POPs), metal-organic frameworks (MOFs), porous organic cages (POCs) and metal halides. The corresponding mechanism and structure-property relationship are discussed in detail. The purpose of this paper is to provide a useful insight into the follow-up materials design for the elemental halogen precuring, and finally get an ideal precuring materials with practical application prospects, so as to improve the usage safety of elemental halogen and reduce the risk of halogen leakage. It is of great significance to environmental protection and sustainable development. Keywords halogen; adsorption; porous materials; metal halide; redox 1 研究背景 卤素作为重要的工业原料, 其年产量与使用量都很 高, 如图 1 所示 [1][2][3][4][5][6] . F 2 被广泛应用于铀同位素的分离 [7] ; Cl 2 在水处理及合成聚氯乙烯等塑料中发挥巨大作用 [8] ; Br 2 被广泛应用于溴化阻燃剂 [9] 、氢溴酸液流电池 [10] 以 及锌溴液流电池 [11] 等领域; I 2 主要用于医药 [12] 、造影 剂 [13] 等行业. 然而由于 F 2 、Cl 2 、Br 2 自身具有极强的毒 性、腐蚀性和挥发性, 一旦发生泄漏或爆炸, 将会造成 严重的后果 [14][15] . F 2 是化工领域的重要原料之一, 它是 通过钝化预处理过的铁、铝等合金或蒙乃尔合金等制成 的钢瓶来运输 [16] . Cl 2 作为重要的工业原料, 一般储存在