Synthesis of Nanosized Mordenite with Enhanced Catalytic Performance in the Alkylation of Benzene with Benzyl Alcohol

We report a facile preparation of nanosized mordenite (MOR) with different morphologies, i.e., nanosized crystals and nanoplatelets. Specifically, nanosized MOR crystals (30–80 nm) in three dimensions (3D) were synthesized in the absence of long-chain organic surfactant as a crystal growth-inhibiting agent by simply decreasing the mole ratio of Na₂O/SiO₂ in synthesis gel. Furthermore, MOR nanoplatelets with 50–100 nm thickness were synthesized using the cooperation of structure-directing agents (SDAs) of tetraethylammonium hydroxide (TEAOH) and hexamethyleneimine (HMI), where the latter was the SDA for the synthesis of 2D layered zeolite MCM-22. Our findings revealed that the introduction of HMI not only affected the morphology of MOR, but also had a considerable impact on the distribution of Brönsted acid sites. Consequently, the nanosized MOR crystals prepared in the absence of HMI exhibited the highest catalytic activity for the alkylation of benzene with benzyl alcohol compared with MOR nanoplatelets and commercial bulky MOR, which can be attributed to the shorter diffusion pathway along the c-axis and enriched Brönsted acid sites in the 12-membered ring (MR) of nanosized MOR crystals.