Modified Acid‐Base ZSM‐5 Derived from Core‐Shell ZSM‐5@ Aqueous Miscible Organic‐Layered Double Hydroxides for Catalytic Cracking of n ‐Pentane to Light Olefins

Enhanced light olefins production via n-pentane cracking using modified MFI catalysts

n-pentane catalytic cracking was studied over a series of MFI zeolites with varying SiO₂/Al₂O₃ ratios (30, 80, 280, 500, and 1500) using a fixed-bed reactor operated at temperature 550–650 °C. Other MFI zeolites (SiO₂/Al₂O₃ = 280) with various crystal morphology and size (such as large crystal and nano size) were also synthesized and tested for n-pentane cracking. The effects of MFI zeolite modification with ammonia and phosphorus on its physiochemical properties and catalytic activity were investigated. Among the parent MFI zeolites, MFI (280) demonstrated high selectivity (51%) towards light olefins (C₃⁼/C₂⁼ = 0.7) at 650 °C with undesired C₁–C₄ alkanes (38%). Surface modified MFI (280) zeolites of different crystal size and morphology showed improvement towards propylene selectivity by suppressing undesired reactions. Phosphorous-modified MFI zeolite with a large crystal size was found to improve light olefin selectivity (52.2%) with C₃⁼/C₂⁼ = ∼1.3 and reduce undesired C₁–C₄ alkanes (8%) formation due to suppressed strong acidic sites. The characterization and evaluation results for the modified MFI (280) revealed that the incorporation of phosphorous created moderate acidic sites, which were stabilized by some non-framework aluminum species, thereby leading to suppressing the formation of undesired C₁–C₄ alkanes with improved light olefins selectivity.

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n-pentane cracking over MFI zeolites with various Si₂O₃/Al₂O₃ ratios (30, 80, 280, 500, and 1500) was investigated.

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MFI (280) zeolite at 650 °C showed 51% selectivity for light olefins (C₃⁼/C₂⁼ = 0.7) with 23.8% undesirable C₂-C₄ alkanes.

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Phosphorous-modified large crystal MFI catalyst with moderate acid sites inhibited hydrogen transfer reaction.

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P/HZ280-LC provide improved light olefins production (selectivity 52.2%, C₃⁼/C₂⁼ = 1.3).

Binder-free hierarchical zeolite pellets and monoliths derived from ZSM-5@LDH composites for bioethanol dehydration to ethylene

The development of industrial catalysts is of crucial importance for practical uses. However, it still suffers from making extruded catalysts because of a remarkably decreased catalytic activity when combining them...

In Situ Synthesis of Sn-Beta Zeolite Nanocrystals for Glucose to Hydroxymethylfurfural (HMF)

The Sn substituted Beta nanocrystals have been successfully synthesized by in-situ hydrothermal process with the aid of cyclic diquaternary ammonium (CDM) as the structure-directing agent (SDA). This catalyst exhibits a bifunctional catalytic capability for the conversion of glucose to hydroxymethylfurfural (HMF). The incorporated Sn acting as Lewis acid sites can catalyze the isomerization of glucose to fructose. Subsequently, the Brønsted acid function can convert fructose to HMF via dehydration. The effects of Sn amount, zeolite type, reaction time, reaction temperature, and solvent on the catalytic performances of glucose to HMF, were also investigated in the detail. Interestingly, the conversion of glucose and the HMF yield over 0.4 wt% Sn-Beta zeolite nanocrystals using dioxane/water as a solvent at 120 °C for 24 h are 98.4% and 42.0%, respectively. This example illustrates the benefit of the in-situ synthesized Sn-Beta zeolite nanocrystals in the potential application in the field of biomass conversion.