Synthesis of SSZ-13 zeolite with zeolite L-added synthesis gel absent from additional aluminum source

• DOI: 10.1016/j.micromeso.2018.11.038
• Publication Date: 2018-11-29T13:56:19Z
• Authors: Yuping Li; Yi Zhang; Aidong Lan; Huimin Bian; Rui Liu; Xiaofeng Li; Peide Han; Tao Dou
• Keywords: 02 engineering and technology; 0210 nano-technology

Abstract SSZ-13 zeolite with a SiO2/Al2O3 ratio in the range of 26–183 was synthesized by adding zeolite L in the synthesis gel absent from additional aluminum source, and the effects of SiO2/Al2O3 and N,N,N-trimethyladamantammonium hydroxide (TMAdaOH)/SiO2 ratios on the crystallization were investigated. The crystallization mechanism was studied with X-ray diffraction, Scanning electron microscopy, Fourier transform infrared spectroscopy and 29Si and 27Al MAS NMR spectroscopy techniques. It is shown that the SiO2/Al2O3 and TMAdaOH/SiO2 ratios have a significant effect on the acidity, and thus, the methanol-to-olefins (MTO) performance of SSZ-13. The co-presence of TMAdaOH, NaOH and extra silica source (SiO2) is necessary for formation of SSZ-13. The crystallization of SSZ-13 occurs by decomposing structure of zeolite L into double six- and four-membered rings that subsequently restructure into CHA topology under the direction of TMAdaOH, and further induce the nucleation and crystal growth. It is noteworthy that the Al species in zeolite L directly transform into those of SSZ-13 without forming monomeric species. The prepared SSZ-13 shows higher catalytic stability and selectivity to ethylene and proplyene than the conventionally synthesized sample from amorphous aluminosilicate gel in MTO reaction.