Synthesis of Nanocrystalline Mordenite Zeolite with Improved Performance in Benzene Alkylation and n‐Paraffins Hydroconversion

Abstract

Nanocrystalline mordenite (MOR) zeolites were hydrothermally synthesized in a single step with commercial cetyltrimethylammonium (CTA) hydroxide as the sole organic template, while the aluminum source was varied in a typical synthesis gel. CTA can effectively reduce the crystal growth of MOR zeolites, in some cases selectively in the a‐ and b‐directions of the unit cell. These nanocrystalline MOR zeolites do not only have a larger external surface area than their bulk counterparts prepared without CTA, but the Brønsted acid sites in the side‐pockets are also more accessible. The combination of the use of CTA and AlCl3 ⋅ 6H2O afforded the best‐performing catalyst with much improved activity in benzene alkylation and hydroconversion of n‐hexadecane (n‐C16). Modifying MOR synthesis with CTA hydroxide is a cheap and effective method to open up the one‐dimensional micropore system of mordenite, increasing the catalytic performance in hydrocarbon reactions.

Zeolite Nanocrystals (MOR, EU-1, and ZSM-12) Synthesized Using a Versatile Diquaternary Ammonium Template as Robust Catalysts

“…51 In conventional synthesis of MOR zeolite under highly alkaline conditions, crystals larger than 100 nm are obtained (Figures 1b and S6), consistent with previous studies. 44,52 EU-1-Con and ZSM-12-Con synthesized from conventional recipes consist of bulky plate-and rugby-ball-like crystals, respectively (Figures 2f and 2j).…”

“…The crystallization behavior of nanocrystalline MOR, EU-1, and ZSM-12 zeolites was investigated by characterizing the intermediate solid products. As the benefit of nanosizing MOR zeolite has been well evidenced in our previous studies, , we focus on investigating the catalytic performance of nanosized EU-1 and ZSM-12 zeolites in the present work. The methanol-to-hydrocarbons (MTH) reaction was chosen as a model reaction to assess the catalytic performance of nanosized EU-1.…”

Acceleration of Zeolite Crystallization: Current Status, Mechanisms, and Perspectives

“… ,,− In 1996, Ragiv Kumar and co-workers pointed out the that the crystallization rate of zeolites could be accelerated by the addition of various “promoter” ions of perchlorate, phosphate, nitrate, sulfate, and carbonate . Subsequently, these additives and their analogues were adopted to prepare the zeolites in varying degrees. , In 2021, Sun and colleagues further exploited the acceleration effects of the anions in silicalite-1 zeolite crystallization at the molecular level. They demonstrated that the anions located in different spatial regions of the hydrated TPA + cations could influence the release of water molecules through activating the hydration nutrient spheres around the TPA + cations at different degrees and subsequently regulated the crystallization process (Figure a) .…”

Wheel-like Mordenite Nanoassemblies with Shortened Channel Lengths for Improved Catalytic Performance in Dimethyl Ether Carbonylation

“…Mordenite is one of the several zeolites that have been industrially applied, such as in isomerization, , alkylation, − toluene disproportionation, etc. MOR exhibits large 12-membered ring (12-MR) channels along the c -axis, which are intersected by 8-MR channels along the b- axis .…”