The inner heterogeneity of ZSM-5 zeolite crystals

Abstract

The inner heterogeneity of ZSM-5 zeolite and the building mechanism of inner architecture in zeolite synthesis was revealed through NH4F-etching. The inner heterogeneity of ZSM-5 zeolite was described by the concepts of defect-zoning and Al-zoning.

Highly selective conversion of mixed polyolefins to valuable base chemicals using phosphorus-modified and steam-treated mesoporous HZSM-5 zeolite with minimal carbon footprint

“…S2c+d). This could have been the result of Al-zoning in the commercial samples [61][62][63], with a more Al-rich rim that was less prone to desilication. Considering the high level of mesoporosity developed in P/mesoZ30, it is possible that the increased steaming severity at 800 • C caused a partial collapse of the structure, leading to a decrease in mesoporous volume compared to the mildly steamed version (Table 1).…”

Advanced scanning electron microscopy techniques for structural characterization of zeolites

“…Moreover, the information extracted from the cross-section is very helpful for the interpretation of the spatial element distribution in the inner part of the zeolite crystals. 24…”

“…Besides the comprehensive observation of the secondary porosity from different perspectives (Fig. 6), a precise study of the distribution of different elements at a single crystal level is of great importance and helpful for the interpretation of the crystallization mechanism 24 and catalytic behavior of zeolites. 6,7 The advantage of combined low voltage and triple-detector EDS analysis in recording the near-surface-layer element distribution in the SAPO-34 crystals is shown here.…”

“…Moreover, the information extracted from the cross-section is very helpful for the interpretation of the spatial element distribution in the inner part of the zeolite crystals. 24 For EDS analysis, there are two important factors to be considered: (1) the SEM conditions affect the spatial resolution of EDS analysis and (2) the solid angle of the detector affects the collection number of characteristic X-rays. Previous reports showed that a low accelerating voltage, namely a low incident electron energy, is suitable for the surface observation, which is also effective for the surface analysis by EDS.…”

Towards a comprehensive understanding of mesoporosity in zeolite Y at the single particle level

“…5 In addition to this usually available technique that measures porosity in an indirect way, complementary electron microscopy techniques are also available for the direct visualization of micro-, mesoand macropore networks. 4,6 In this respect, both scanning and transmission electron microscopy techniques are very popularly used for the direct visualization of zeolite porosity. 7,8 In both cases, the presence of pores is clearly reflected by the darker/lighter image contrast difference.…”