Plate-Like ZSM-5 Zeolites as Robust Catalysts for the Cracking of Hydrocarbons

Abstract

Zeolites with good acid site accessibility and high diffusion rates are highly desirable catalysts, especially when dealing with bulk molecules. In this work, ZSM-5 zeolites with similar Si/Al ratios but different thicknesses along the b-axis (from ∼30 nm to ∼5 μm), namely, two plate-like ZSM-5 zeolites and two reference zeolites have been prepared and the impacts of b-axis thickness on the surface properties and catalytic cracking performances are explored. Comprehensive physiochemical studies demonstrate that reducing the b-axis thickness of the zeolite crystals endows the samples with better acid site accessibility and more external surface acid sites. Two model compounds with different molecule sizes, namely, 1,3,5-triisopropylbenzene (TIPB) and cumene, are selected to explore the catalytic cracking performances of the as-synthesized samples. The results reveal that decreasing the b-axis thickness of zeolite crystals can effectually promote the catalytic activity and stability in catalytic cracking reactions. For TIPB cracking, the greatly enhanced catalytic activity is ascribed to the enhanced acid site accessibility in plate-like ZSM-5 zeolites, and for cumene cracking, the improved catalytic stability is ascribed to the shortened diffusion length of plate-like zeolites.

Tuning Pt Location and Intimacy between Pt–Acid Active Sites in Pt/ZSM-5 Bifunctional Catalysts for Effective Alkylation of Benzene with Ethane

“…It is observed that all of the samples exhibit characteristic diffraction peaks attributed to the MFI topology of the typical ZSM-5 phase. These high-intensity peaks also demonstrate that these samples are well-crystallized ZSM-5 zeolites . However, the diffraction peaks of Pt (prominent peaks should be at 2θ = 39.8, 46.2, and 67.4°) are not detected over Pt-load samples.…”

Anchoring Effect of Organosilanes on Hierarchical ZSM-5 Zeolite for Catalytic Fast Pyrolysis of Cellulose to Aromatics

“…It is generally accepted that the SiOHAl groups (corresponding to Si­(1Al,3Si)) can offer Brønsted acid sites and strong acid sites for zeolites and SiOH can offer weak acid sites. It is interesting to note that zeolites prepared with OSA show a higher content of Si­(1Al,3Si) and SiOH sites (Figure S1) compared with Blank-Z5, leading to the increase of acid amount. ,− According to 29 Si MAS NMR spectra, we can conclude that OSA can modulate the coordination environment of Si in zeolites and thus promote the formation of acid sites.…”

HZSM‐5‐Catalyzed Vapor‐Phase Conversion of Dimethyl Adipate to Adiponitrile: The Influence of the SiO2/Al2O3 Ratio on Reactivity

“…[15][16][17][18] H-forms of ZSM-5 (HZSM-5), as a typical MFI zeolite, is widely used in the field of petrochemical catalysis and has unique advantages in high specific surface area and adjustable acid properties. [19][20][21][22] Remarkably, the acid properties of HZSM-5, including the amount, type, strength, and distribution of acid sites, could be facilely modulated by altering the SiO 2 /Al 2 O 3 ratio (SAR). [23][24][25][26] In addition, the hydrophilicity or hydrophobicity of the surface can also be adjusted accordingly.…”