Self-standing zeolite foam monoliths with hierarchical micro–meso–macroporous structures

Abstract

The zeolite monoliths were synthesized by a facile polymer scaffold template assisted hydrothermal method. The selected foam-shaped template of a polyurethane (PU) foam monolith, was used to prepare the self-standing zeolite foam (ZF) monolithic materials. The obtained ZF products can preserve the same size, shape and macroporous network structure of the original PU foam scaffold template, although the zeolite nano-crystallites had been fully substituted for the PU template to form the new skeleton struts and walls. The as-synthesized ZF products demonstrated abundant hierarchical porosity (involving triple micro-, meso- and macropores). Meanwhile, compared with the conventional zeolite powders, the self-standing ZF monolithic materials exhibited greater total pore volume and nearly three times higher mesopore volume, suggesting wider applications as catalysts, catalyst supports and adsorbents in industry.

Preparation and Potential Catalytic Applications of Hierarchically Structured Zeolites with Macropores

“…Templating with preshaped macroscopic structured precursors: Different macroscopic structured precursors such as silica monoliths, preshaped amorphous alumosilicates, [ 41 ] biological scaffolds, [ 32 ] polymers, [ 42 ] carbon structures, [ 43 ] ion exchange beads, [ 44 ] emulsions, [ 45 ] spray dried beads, [ 46 ] extrudates, [ 47 ] porous glass, [ 48 ] silica gel, [ 49 ] or even 3D printed precursors [ 50 ] have been successfully completely zeolitized. From this long list, these precursors can be classified as natural occurring and synthetic.…”

“…Additionally, the burning of sometimes expensive IER possess serious environmental problems. Alternative to such expensive sacrificial pre‐shaped templates can be the use of cheap biomass derived templates, [ 42b ] biological templates, [ 54 ] polymers, [ 33a ] or even pre‐shaped macrotemplates from emulsions. [ 54 ]…”