Synthesis of nano-SSZ-13 and its application in the reaction of methanol to olefins

Abstract

Nanosized SSZ-13 has been obtained from a one-pot synthesis procedure with the addition of CTAB to the synthesis precursor solution. Nano-SSZ-13 zeolite showed high intracrystalline mesoporosity and comparing to standard SSZ-13 presented much longer lifetime and higher conversion capacity for the reaction of methanol to olefins. The improved properties were attributed to a more efficient utilization of microporosity by easier diffusion of reactants and products and slower deactivation by coke. A higher C2/C3 ratio was found for nano-SSZ-13 pointing to a lower deactivation of the aromatics cycle of the hydrocarbon pool.

Synthesis of reaction‐adapted zeolites as methanol-to-olefins catalysts with mimics of reaction intermediates as organic structure‐directing agents

“…The nanosized SSZ-13 was prepared by combining the use of TMAda as OSDA and a surfactant molecule (cetyltrimethylammonium, CTMA) as organic modifier (see physicochemical properties for the SSZ-13_nano in Supplementary Table 3). 37,38 As seen in Table 1, the catalytic lifetime of the SSZ-13_OSDA1a zeolite is remarkably lower than that observed for the SSZ-13_std, due to the lower Si/Al molar ratio of the former (Si/Al=6). 31 However, the SSZ-13_OSDA1b zeolite presents comparable Si/Al molar ratios (Si/Al=15) to other related-CHA zeolites used previously in the literature for the MTO reaction, as it is the case of the SSZ-13_std and SSZ-13_nano, 37 .…”

“…Thus, from the different SSZ-13 samples obtained with OSDA1b, we selected one sample with a Si/Al ratio of 15 (see SSZ-13 in Supplementary Figure 7), since the standard SSZ-13 reported in the literature synthesized using N,N,N-trimethyladamantammonium (TMAda) as OSDA is usually prepared with that Si/Al molar ratio. 36,37 Owing to the high catalytic activity of these SSZ-13 zeolites the MTO reaction has been carried out at 350C, with a WHSV of 0.8 h -1 . For comparison purposes, a standard SSZ-13 zeolite has been prepared (see physico-chemical properties for the SSZ-13_std in Supplementary Table 3).…”

Making Nanosized CHA Zeolites with Controlled Al Distribution for Optimizing Methanol‐to‐Olefin Performance

“…On the other hand, two different synthesis of Na‐containing nano‐sized CHA materials reported in the literature have been prepared, a surfactant‐modified SSZ‐13 and the SSZ‐62 zeolite . The synthesis gels of these two materials require Si/Al molar ratios close to about 15, the presence of sodium hydroxide, and the use of TMAda + as OSDA (see Table and experimental details in the Supporting Information).…”

“…The synthesis gels of these two materials require Si/Al molar ratios close to about 15, the presence of sodium hydroxide, and the use of TMAda + as OSDA (see Table and experimental details in the Supporting Information). First, the surfactant‐modified nanosized Na‐SSZ‐13 involves the introduction of cetyltrimethylammonium (CTMA + ) in the synthesis media after a previous ageing treatment, to prevent the excessive crystal growth . The achieved material shows small and plane‐based CHA crystallites, with crystal sizes ranging from 50 to 150 nm (see CHA_7 in Figure ), and a large external surface area (ca.…”

Optimized Synthesis of ZSM‐11 Catalysts using 1,8‐Diaminooctane as a Structure‐Directing Agent

“…MTH reactions were carried out in a fixed bed reactor at 350 °C and a weight hourly space velocity of 9 h −1 . Prior studies have shown that increased catalyst size generally results in shorter lifetime due to increased diffusion limitations that enable faster rates of coking (or catalyst deactivation) . Crystal size can also have a notable effect on MTH product selectivity, as demonstrated by Bhan and co‐workers for MFI catalysts .…”