Development of mesopore-containing CON-type zeolite with unique acidic and catalytic properties

Abstract

<p>Post-synthetic hydrothermal treatment in NH₄OH solution containing cetyltrimethylammonium bromide.</p>

Robust CON-type zeolite nanocatalyst in methanol-to-olefins reaction: downsizing, recrystallisation and defect-healing treatments toward prolonged lifetime

“…The recrystallised zeolite showed an increased lifetime of 9 h owing to its increased external surface area. In contrast, the defect-healed zeolite exhibited a remarkably increased lifetime of 15 h. Compared to the previously reported results for the CON-type zeolite catalysts for an MTO reaction 19 synthesised via hydrothermal and alkaline treatments, the defect-healed zeolite in this study exhibited a 100% conversion rate for a longer time, under similar reaction conditions. Fig.…”

“…15 CIT-1, the first CON-type zeolite with pure polymorph B, was synthesised in a borosilicate framework 16,17 and an aluminium-containing CON-type zeolite 15 was also reported. Syntheses of CON-type zeolites with the enhanced catalytic performance have been demonstrated by means of heteroatom substitution, 18 mesopore introduction 19 and control of particle size and acid-site location. 20 However, their catalytic performance is still insufficient, and the development of CON-type zeolite catalysts with high C 3 –C 4 selectivities and long catalytic lifetimes remains a challenge.…”

Methanol‐to‐Olefins Reaction over Large‐Pore Zeolites: Impact of Pore Structure on Catalytic Performance

“…Thus, the zeolite with mild or weak acid strength may show high selectivity for propylene and low selectivity for ethylene, leading to a high P/E ratio 39, 45. However, it should be noted that the high P/E ratio achieved over [Al,B]‐CON could be due to the participation of the reaction intermediate that selectively produces propylene instead of ethylene as observed over Beta zeolite 16, 17, 46.…”

“…3). In the MTO reaction, the formation of ethylene can be explained by the aromatic-based hydrocarbon pool cycle where the aromatic hydrocarbons retained inside the micropores of zeolite structures participate in the formation of light olefins by continuous methylation and cracking reactions [6], and these reactions may require the stronger acid sites located at large space [45,46]. Thus, the zeolite with mild or weak acid strength may show high selectivity for propylene and low selectivity for ethylene, leading to a high P/E ratio [39,45].…”

“…Among them, zeolites consisting of 12-and 10-ring channels have been of current interest in the MTO reaction due to their unique catalytic performance [39][40][41][42][43][44][45]. Zeolite frameworks consisting of 12-and 10-ring channels, namely, MSE-and CON-type materials, have already been applied in dimethyl ether-to-olefins (DTO) [39][40][41] and MTO reactions [44][45][46], and both materials showed high P/E ratio in the products and the deactivation rate was relatively slow which would be a combination of the catalytic properties of Beta and ZSM-5 zeolites. Furthermore, they showed relatively higher selectivities for butylenes than that obtained over ZSM-5 zeolite with comparable Si/Al ratio, indicating that they are the promising catalyst candidates for the selective production of propylene and butylenes in the MTO reaction.…”