Fig. 4.

In situ data supporting the assumed mechanism of VPT. a In situ XRD demonstrating changes during the hydrolysis of the parent IWW zeolite; b in situ XRD collected during thermal treatment of IPC-18P; c variation of lattice parameters (lengths in Å and angle in degree) as a function of time during the VPT treatment; d evolution of the primary line extracted from in situ XANES spectra representing changes in Ge state during hydrolysis steps; e proposed mechanism (Si and Ge atoms are not distinguished for clarity and only structural, but not chemical, changes are shown). Full in situ XRD data, lattice parameters and XANES profiles are shown in Supplementary Figs. 5, 6 and 7, respectively. Analysis of the variation of lattice parameters and position of primary line in XANES spectra allows to distinguish several steps during VPT. Unexpectedly, the disassembly of Ge-rich D4Rs was accompanied by partial disorder of the layers, which become more crystalline on the second step of hydrolysis. The topology of resulting layers only slightly differs from that of starting zeolite. Following deintercalation of interlayer debris and condensation allows the formation of new IPC-18 zeolite