Syntheses of MTT-Type Zeolites with the Presence of Both Octyltrimethylammonium Chloride and SFE-Type Zeolite Seeds

Abstract

Structure-directing agents (SDAs) play important roles in directing the formation of specific zeolite frameworks. Mechanisms and working hypothesis were proposed for understanding how SDAs work during the crystallization of zeolites. The lately reported cooperative structure-directing effect based on the investigation into the synthetic system containing both seed and organic species is one of them and is believed to be effective for synthesizing zeolites which are difficult to access or with novel structures. However, more examples are still needed to support the thesis. Herein, we report for the first time the syntheses of MTT -type zeolites with the simultaneous presences of octyltrimethylammonium chloride (OTMAC) and SFE zeolite seeds in the borosilicate system. SFE borosilicate zeolites serve as exotic seeds for the crystallization of MTT -type zeolites and together with OTMAC play cooperative structure-directing roles. Besides, Al,B- MTT and heteroatom (Zr, V, and Fe)-incorporated MTT -type zeolites were directly synthesized with the introduction of metal sources into the borosilicate system. Physicochemical properties of the obtained MTT zeolites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N 2 physisorption, NH 3 -TPD, 27 Al NMR, 13 C NMR, 11 B NMR, UV–visible spectroscopy, and UV Raman spectroscopy. The herein-reported phenomenon provides an example to better understand the mechanism of zeolite crystallization, and the synthesized zeolites may act as promising catalytic materials in several organic reactions.

Synthesis of ZSM-22 Zeolite Nanosheets with Improved Stability in the Catalytic Conversion of Methanol to Hydrocarbons

“…The 27 Al MAS NMR spectra show obvious single resonance peak for all samples at a chemical shift (δ) of about 55 ppm corresponding to tetrahedral-coordinated Al species, and there is no signal detected at a chemical shift of 0 ppm, which corresponds to extra-framework Al. 46 The results confirm that tetrahedral-coordinated alumina basically exists in the crystallized ZSM-22 framework (Figure 5A). The presence of silicon species coordinated with the framework aluminum was confirmed by the 29 Si MAS NMR spectra (Figure 5B).…”

“…The total weight losses are 9.0, 8.4, 8.4, and 7.2% for C-ZSM-22, F-ZSM-22, U-ZSM-22, and FU-ZSM-22 (Table S1), respectively. The weight loss could be divided into two stages: (I) between about 200 and 320 °C, ascribed to the desorption of water or a part of OSDA located near the surface of crystals; (II) above 320 °C, due to the removal of OSDA located in the zeolite channels. − The corresponding detailed weight loss of the ZSM-22 zeolites is presented in Table S1. In FU-ZSM-22, the amount of OSDA present in the channels (stage II) is about 60%, while the values are about 83, 82, and 77% for C-ZSM-22, F-ZSM-22, and U-ZSM-22, respectively.…”

SCM-36 zeolite nanosheets applied in the production of renewable p-xylene from ethylene and 2,5-dimethylfuran

“…The liquid 13 C NMR spectrum was recorded on a Bruker AV-400 spectrometer. 13 C, 29 Si and 27 Al solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) measurements were performed on a JNM-ECZ500R/S1 (JEOL) spectrometer under one-pulse condition.…”

“…The liquid 13 C NMR spectrum was recorded on a Bruker AV-400 spectrometer. 13 C, 29 Si and 27 Al solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) measurements were performed on a JNM-ECZ500R/S1 (JEOL) spectrometer under one-pulse condition. The 13 C MAS NMR spectra were recorded at a 13 C frequency of 125.765 MHz and a spinning rate of 18.0 kHz with a π/2 rad pulse length of 5.0 μs, 13 C chemical shifts were reported relative to adamantane (ADA).…”

“…There are examples of zeolite syntheses using two different organic SDAs [9,[13][14][15][16], a combination of an OSDA and an ISDA [17], and a combination of an OSDA and zeolite seed [18][19][20]. It is capable to control structure formation [17], adjust morphology and compositions of framework atoms and crystalline phases [21,22].…”