ZTS-1 and ZTS-2: Novel intergrowth zeolites with AFX/CHA structure

Tunable CHA/AEI Zeolite Intergrowths with A Priori Biselective Organic Structure‐Directing Agents: Controlling Enrichment and Implications for Selective Catalytic Reduction of NOx

“…Current synthesis methods for high‐silica CHA/AEI intergrowths rely on the use of expensive OSDA mixtures, such as N , N , N ‐trimethyladamantylammonium (TMAda) and N , N ‐diethyl‐2,6‐dimethylpiperidinium (DEDMP), [11] two well‐known OSDAs to synthesize pure CHA and AEI phases, respectively [12–14] . This dual‐OSDA approach was recently described for guiding the synthesis of high‐silica CHA/AFX intergrowths using 1,1′‐(1,4‐butanediyl)bis(1‐azonia‐4‐azabicyclo[2,2,2]octane) dication and TMAda as the specific OSDAs for AFX and CHA, respectively [15] . Although the dual‐OSDA methodology can be extended to other industrially attractive zeolite intergrowths, two very specific OSDA molecules are needed under strictly fine‐tuned conditions to avoid the crystallization of the independent zeolite phases, increasing the preparation complexity and costs of the final materials.…”

“…[12][13][14] This dual-OSDA approach was recently described for guiding the synthesis of high-silica CHA/AFX intergrowths using 1,1'-(1,4-butanediyl)bis(1-azonia-4azabicyclo[2,2,2]octane) dication and TMAda as the specific OSDAs for AFX and CHA, respectively. [15] Although the dual-OSDA methodology can be extended to other industrially attractive zeolite intergrowths, two very specific OSDA molecules are needed under strictly fine-tuned conditions to avoid the crystallization of the independent zeolite phases, increasing the preparation complexity and costs of the final materials. This problem is further exacerbated when trying to control the phase-enrichment within the intergrown zeolite crystals, while avoiding phase segregation.…”

Recent progress in the improvement of hydrothermal stability of zeolites

“…This method allowed obtaining new zeolitic structures 129–132 and introducing phosphorus into small pore materials that cannot be achieved by standard post-synthesis treatments because of the limited diffusion of phosphates through 8R windows. Small pore zeolites AEI, 133–135 CHA, 136 AFX, 137 LEV, 122 GME 138 and AFX/CHA 139 have been prepared by using a dual-template method where the typical OSDA employed in the crystallization of the zeolite was mixed with tetraethylphosphonium or tetramethylphosphonium hydroxide ( Table 1 ). The presence of tetraalkylammonium (N-OSDA) and tetraalkylphosphonium (P-OSDA) can be confirmed by 13 C CP/MAS NMR spectroscopy, and in the case of the AFX zeolite the characteristic shifts of both organic molecules can be distinguished in the 13 C CP/MAS NMR spectrum ( Fig.…”

Effect of hydrothermal aging temperature on a Cu-SSZ-13/H-SAPO-34 composite for the selective catalytic reduction of NOxby NH3

“…Cu-zeolites with a combination of two zeolite structures showed enhanced HTA stability over single catalyst. For example, Cu-ZST-1 (AFX/CHA), 15 Cu-SAPO-34/5 (CHA/AFI), 16 and Cu-OFF/CHA 17 composites exhibited improved hydrothermal stability than the individual component. Our previous work also showed that the mixed Cu-SSZ-13/Cu-SAPO-34 composites performed a much better HTA stability than Cu-SSZ-13, due to the intense interaction between the two components (SSZ-13 and SAPO-34) during HTA.…”