Germanosilicate Precursors of ADORable Zeolites Obtained by Disassembly of ITH, ITR, and IWR Zeolites

Structure transformation of germanosilicate zeolites ITH, ITR, and IWR containing hydrolytically unstable interlayer Ge–O bonds was investigated and is related to the conditions of acidic treatment (i.e., concentration of hydrochloric acid, temperature, duration). The disassembly of ITH (Si/Ge = 2.5), ITR (Si/Ge = 2.4), and IWR (Si/Ge = 6.9) zeolites under appropriate acidic treatment was demonstrated. Low-concentration acid solutions (e.g., 0.01 M HCl) and low temperatures favor the hydrolysis of the zeolites under study. The chemical composition of the parent zeolites strongly influences the efficiency of hydrolysis. For zeolites having sufficient fraction (ca. 50%) of Ge in D4R units (Si/Ge ≤ 6 for ITH and IWR, Si/Ge ≤ 3.7 for ITR ), transformation into layered materials (two-dimensional zeolites) was successful while the lowering of Ge concentration resulted in only a partial separation of the ITH and ITR crystalline layers. The acidic treatment of medium-pore ITR and ITH zeolites with HCl at ambient temperature for 24 h is optimal for selective cleavage of almost all interlayer Ge–O bonds, while transformation of large-pore IWR zeolite into layered material was observed even after only 5 min of the treatment. These results evidence the general applicability of the ADOR mechanism for the synthesis of new zeolites.