The influence of swelling agents molecular dimensions on lamellar morphology of MWW-type zeolites active for fructose conversion

Abstract

A new route to obtain pillared, disordered or desilicated MWW-type zeolites was developed assisted by quaternary ammonium surfactants with different hydrocarbon tail size acting as swelling agents (C12TA +, C16TA +, C18TA +). Effect of surfactant concentration and swelling conditions were determinant to obtain MWW-type zeolites with different lamellar organization and spatial distribution of individual zeolitic layers. Specifically, soft swelling at 25 °C preserved layer structure instead of aggressive processes at 80 °C that favored desilication, damaging the layers structure in case of C12TA + and C16TA + and C18TA +. It was proved that surfactant size combining with swelling and pillaring procedure influenced on physico-chemical and morphological nature of MWW-type materials. The obtained derivative MWW zeolites with different morphology, order and acessibility levels were firstly evaluated by catalitic dehydration fructose to 5hydroxymethylfurfural showing, superior activity compared to commercial zeolite catalyst.

Lamellar MWW-Type Zeolites: Toward Elegant Nanoporous Materials

“…When NaOH is used, the small Na + cations rapidly enter the interlamellar region and compensate negatively charged ions before populating the CTA + molecules in the interlamellar region, resulting in an unsuccessfully or partially swollen material [44]. Several studies have sought to better understand swollen materials using different swelling conditions (room temperature or 80 • C), molecular dimensions of swelling agents, hydroxide sources, and strategies of recycling and reusing the swelling solution [45][46][47][48][49][50].…”

Dandelion-Like Microspherical MCM-22 Zeolite Using BP 2000 as a Hard Template

“…The synthesis of the (P)MCM-22 precursor with a Si/Al = 25 molar ratio was done similar to the literature . 39 Under stirring, 9.25 mmol of sodium hydroxide (NaOH, Sigma-Aldrich) and 4.51 mmol of sodium aluminate (NaAlO 2 , Riedel-de-Haën) were dissolved in 4.51 mol of distilled water. Then, 50.21 mmol of HMI (Sigma-Aldrich) and carbon black BP 2000 (Cabot) were added into the mixture.…”

The influence of ethanol-assisted washes to obtain swollen and pillared MWW-type zeolite with high degree ordering of lamellar structure

“…Swelling of the LZP was similar to the procedure reported in literature [7]. The swelling LZP was carried out at room temperature with 1.80 g of LZP, 7.20 g of distilled water, 35.00 g of an aqueous solution of 29 wt% CTABr/OH with 51% of ionic exchange and 11.0 g of an aqueous solution of 40 wt% TPABr/OH with 45% of ionic exchange.…”

“…On the other hand, few topologies form lamellar zeolitic precursors (LZPs) propagated in only two-dimensions [4]. The LZPs offer great versatility to create open pore structures (pillared, exfoliated, disordered, desilicated, hybrid) with improved access for larger molecules than the microporous channels of zeolites (less than 1 nm) [5][6][7][8]. Among the best example of lamellar zeolitic precursors, the LZP of the MCM-22 (MWW topology) zeolite is the most versatile for post-synthetic modifications.…”

“…The swelling procedure was studied using soft (25 °C) or aggressive (80 °C) treatments showing that structural integrity and long-range ordering of lamellar structure were obtained with soft swelling procedure [16]. Recently, we reported the influence of molecular dimensions of swelling agents (C12TA + , C16TA + , C18TA + ) combined with soft and aggressive swelling procedures to obtain tunable properties such as surfactant accommodation between lamellae, surface area, pore sizes and acidic nature [7]. Furthermore, an economical and eco-friendly procedure based on the reuse of the recyclable swelling solution was reported and showed that is possible to obtain swollen MWW-type LZP for three times with no compromise the physicochemical properties of the pillared material [17].…”