Seed- and solvent-free synthesis of ZSM-5 with tuneable Si/Al ratios for biomass hydrogenation

Abstract

Seed- and solvent-free synthesis of MFI zeolites with tuneable Si/Al ratios (18-∞) was achieved. The key role of F− was evidenced that forming 6-coordinated “F–Al–O–Si” species drove the formation of the zeolitic framework during crystallization.

Seed-Assisted Synthesis of Zeolite Beta from Solid-State Conversion of Magadiite and an Investigation on the Crystallization Mechanism

“…As shown in Figure , it was surprising to see that hexacoordinated aluminum was always present in the process of crystallization. The same phenomenon also occurred in the synthesis of MOR zeolite and CHA zeolite as previous studies reported. , Recently, Zhang et al reported a novel solvent-free and seed-free method for the synthesis of ZSM-5 in the F – cation system . They used 1D 19 F and 27 Al NMR and 2D 27 Al- 19 F HETCOR NMR to investigate the changes of F and Al atoms during the crystallization.…”

“…44,45 Recently, Zhang et al reported a novel solventfree and seed-free method for the synthesis of ZSM-5 in the F − cation system. 46 They used 1D 19 F and 27 Al NMR and 2D 27 Al- 19 F HETCOR NMR to investigate the changes of F and Al atoms during the crystallization. They found that the appearance of hexacoordinated "F−Al−O−Si" species at 9 ppm in 27 Al NMR (probably in the form of [AlF x (OSi-(OH) 3 ) 6−x ] 3− ) should play a crucial role in the crystallization process because they can lead to the construction of tetrahedral [AlO4] − units in the ZSM-5 framework.…”

Solid-State and Organic Template-Free Synthesis of Zeolite Omega by Conversion of Magadiite in the Presence of Seed Crystals and Investigation of Conversion Mechanism

“…32 Zhang et al reported a novel solvent-free and seed-free method for the synthesis of ZSM-5 in an F − cation system, and they used one-dimensional (1D) 19 F and 27 Al NMR and 2D 27 Al− 19 F HETCOR NMR to investigate the changes in F and Al atoms during the crystallization. 33 They found that the appearance of hexacoordinated "F−Al−O−Si" species (probably in the form of [AlF x (OSi(OH) 3 ) 6−x ] 3− ) should play a crucial role in the crystallization process because they can lead to the construction of tetrahedral [AlO4] − units in the ZSM-5 framework. Hence, due to the fact that hexa-coordinated aluminum appeared at the growth stage of zeolite omega after 2 h, we supposed that a type of hexa-coordinated Al species would appear during the conversion process, and they could effectively help aluminum atoms into the structure of zeolites in the form of AlO 4 − , thus promoting the growth of zeolite omega.…”

“…Recently, many literature works have reported that an extra framework would appear in the solvent-free synthesis of MOR and CHA. , In these literature works, a peak at around 8–9 ppm attributed to octahedral coordinated Al can be detected in 27 Al MAS NMR, which could be assigned to extra-framework aluminum or hydrated-framework aluminum . Zhang et al reported a novel solvent-free and seed-free method for the synthesis of ZSM-5 in an F – cation system, and they used one-dimensional (1D) 19 F and 27 Al NMR and 2D 27 Al– 19 F HETCOR NMR to investigate the changes in F and Al atoms during the crystallization . They found that the appearance of hexa-coordinated “F–Al–O–Si” species (probably in the form of [AlF x (OSi­(OH) 3 ) 6– x ] 3– ) should play a crucial role in the crystallization process because they can lead to the construction of tetrahedral [AlO4] − units in the ZSM-5 framework.…”

Advances in Catalytic Applications of Zeolite‐Supported Metal Catalysts

“…Besides the furfural, other biomass‐based platform compounds could also be converted to target chemicals with high selectivity over zeolite‐encaged metal catalysts, such as 5‐hydroxymethylfurfural to diketone derivatives over Pd/Beta catalyst, [ 100f ] 5‐hydroxymethylfurfural to 2,5‐dimethylfuran over Co/Beta catalyst, [ 103 ] 5‐hydroxymethylfurfural to 2,5‐dimethylfuran over Ru/NaY catalyst, [ 104 ] levulinic acid to γ‐valerolactone over Ru/ZSM‐5 and catalyst, [ 105 ] and methylcyclopentane to C 6 ‐cyclic products over bifunctional Pt@SOD and HZSM‐5 catalyst. [ 106 ]…”