Catalyst Separation, Recovery, and Recycling: chemistry and process design

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW), commonly called as CL-20, is a high energy and high density material of keen interest to both commercial and scientific worlds due to its greater insensitivity (reduced sensitivity) along with a positive high heat of formation, which is due to the azanitro groups attached to the skeleton of HNIW and its highly strained cage structure. It plays a remarkable role in modification and replacement of most of the propellant (gun and rocket) preparations. In this report we present the comparative strategies involved in the syntheses of HNIW with respect to economical and environmental aspects. Various methods reported in the literature on the purification of the crude HNIW (α-HNIW) to obtain ε-form of HNIW (high dense/more potential) are consolidated. Understanding of the structure, morphology, energetics, thermal behavior and their modification to meet the applicability (decreased impact sensitivity) determines the industrial application of HNIW. A compilation of the available literature on the aforementioned characteristic properties for obtaining a value added ε-HNIW is discussed here. This overview also reports the literature available on newer forms of HNIW including derivatives and cocrystals, which increase the performance of HNIW.