Catalytic Cracking of n-Dodecane to Chemicals: Effect of Variable-Morphological ZSM-5 Zeolites Synthesized Using Various Silica Sources

Abstract

This study emphasizes tuning the synthesis conditions of MFI zeolites to achieve better catalytic properties by optimizing the mesoporosity, the balance between Brønsted and Lewis sites, and the zeolite particle sizes. The MFI zeolites were hydrothermally synthesized at various temperatures employing different silica sources. The synthesis temperature was varied between 110 to 180 °C at constant synthesis time (15 h). Different silicon sources led to variations in structure, morphology, and size of the MFI zeolite along with tuned Lewis and Brønsted acid sites in parallel correlation with shape selectivity of the reaction. The catalytic activities of synthesized zeolites were investigated in the catalytic cracking of n -dodecane to produce value-added chemicals. The zeolite synthesized at 180 °C using fumed silica presented the highest catalytic conversion (96.6%), while maximum light olefin gaseous products (73.1%) were obtained for the sample synthesized at 140 °C using tetraethyl orthosilicate as the silica source. The MFI zeolite synthesized at 180 °C employing tetraethyl orthosilicate as a silica source facilitated the formation of both naphthenes and aromatics (71.3%) as major liquid products.

Steam Catalytic Cracking of n-Dodecane to Light Olefins over Phosphorous- and Metal-Modified Nanozeolite Y

“…The introduction of Zr to zeolite Y increased Brønsted acid density and increased heavy oil conversion, while incorporation of Co decreased the amount of coke . Previously, we have reported morphology–activity dependence in n -dodecane cracking . In this study, nanozeolite Y and modified nanozeolite Y with phosphorous and metals were synthesized without a template.…”

“… 21 Previously, we have reported morphology–activity dependence in n -dodecane cracking. 22 In this study, nanozeolite Y and modified nanozeolite Y with phosphorous and metals were synthesized without a template. The physicochemical properties of the catalysts were characterized.…”

Review on the Catalytic Conversion of Naphtha to Aromatics: Advances and Outlook

“…However, these materials are microporous in nature and frequently impede diffusion and result in mass transport restrictions when used in a variety of catalytic applications. These zeolites are modified to have a hierarchical porous structure following different methods to circumvent these problems, e.g., alkaline treatment (desilication), acid or steam treatment (dealumination), synthesis in clear solution (nanocrystals), synthesis with a bifunctional organic surfactant (nanosheets), and micelle-templating-assisted alkaline treatment. , …”

ZSM-5 Catalysts for MTO: Effect and Optimization of the Tetrapropylammonium Hydroxide Concentration on Synthesis and Performance

“… 8 The eight-ring (3.8 × 3.8A) cage like structured SAPO-34 allows the reaction to progress between hydrocarbons and methanol or DME molecules inside these cages. ZSM-5 zeolites 9 with straight (5.3 × 5.6A) and sinusoidal (5.1 × 5.5A) 10-ring channels having strong acid sites enhance the selectivity of propylene by means of olefin methylation and cracking reactions. 10 Furthermore, due to the limited reaction space inside the pores, coke production is limited to only the external surfaces.…”