Facile Synthesis of a Novel Hierarchical ZSM‐5 Zeolite: A Stable Acid Catalyst for Dehydrating Glycerol to Acrolein

Abstract

Catalytic biomass conversion is often hindered by coking. Carbon compounds cover active surface and plug pores, causing catalyst deactivation. Material design at the nanoscale allows tailoring of the catalytic activity and stability. Here, we report a simple synthesis of nanosized ZSM‐5 materials by using a silicalite‐1 seeding suspension. ZSM‐5 crystals were grown from a deionized silica source in the presence of ammonia. By using silicalite‐1 seeds, crystalline ZSM‐5 is synthesized without any structure‐directing agent. This method allows parallel preparation of a range of ZSM‐5 samples, eliminating time‐consuming ion‐exchange steps. Mesoporosity is introduced by formation of intercrystallite voids, owing to nanocrystal agglomeration. The effects of crystal sizes and morphologies are then evaluated in the catalytic dehydration of glycerol to acrolein, with results compared against commercial ZSM‐5. The most active nanosized ZSM‐5 catalysts were five times more stable compared with commercial ZSM‐5, giving quantitative conversion and twice the acrolein yield compared with the commercial catalyst. The influence of the catalyst structure on the chemical diffusion and the resistance to coking are discussed.

Ceria‐Zirconia/Zeolite Bifunctional Catalyst for Highly Selective Conversion of Syngas into Aromatics

“…Besides, it will enable a closer proximity between zeolite and oxide after being integrated with CZS. Therefore, we synthesized a nano‐sized HZSM‐5 by using a Silicalite‐1 seeds‐assistant method . The average crystal size of nano‐HZSM‐5 is 150 nm while that of micro‐sized HZSM‐5 is 2.0 μm (Figure a & 4b).…”

Porous Silicon-Based Catalysts for the Dehydration of Glycerol to High Value-Added Products

“…In the same way, Beerthuis et al compared a commercial H-ZSM-5 with a hierarchical H-ZSM-5, micro-H-ZSM-5, and nano-H-ZSM-5 [ 76 ], being the catalytic results directly related to textural parameters. In this sense, the hierarchical H-ZSM-5 zeolite, with a higher pore volume and lower microporosity, reached the highest glycerol conversion and selectivity to acrolein, while the micro-H-ZSM-5, formed by microsized crystals with small micropores, suffered a faster deactivation by pore blocking.…”

The Role of External Acidity of Hierarchical ZSM‐5 Zeolites in n‐Heptane Catalytic Cracking

“…However, the catalytic applications of ZSM‐5 zeolites are limited by mass transport in the microporous network if bulky molecules are involved in the reaction . In this regard, the introduction of mesopores into microporous zeolites to obtain hierarchical ones, possessing the catalytic features of microporosity and the improved mass transport consequence of mesoporosity, would be an optimal choice for better performance …”

“…[7,8] However,t he catalytic applications of ZSM-5 zeolitesa re limited by mass transport in the microporous network if bulky molecules are involved in the reaction. [9][10][11][12][13] In this regard,t he introduction of mesopores into microporous zeolites to obtain hierarchical ones,p ossessing the catalytic features of microporosity andt he improved mass transport consequence of mesoporosity, [14][15][16][17][18][19][20] would be an optimal choice for better performance. [21][22][23][24][25] Generally,t he acidic properties and the pore structure of hierarchical zeolites are the two main factorst od etermine the catalytic performance duringr eactions.…”