The influence of reactor fluid-dynamics during zeolite synthesis: The synthesis and the cracking activity of hierarchical ERS-10 A zeolite

Intergrowth Zeolites, Synthesis, Characterization, and Catalysis

Microporous zeolites that can act as heterogeneous catalysts have continued to attract a great deal of academic and industrial interest, but current progress in their synthesis and application is restricted to single-phase zeolites, severely underestimating the potential of intergrowth frameworks. Compared with single-phase zeolites, intergrowth zeolites possess unique properties, such as different diffusion pathways and molecular confinement, or special crystalline pore environments for binding metal active sites. This review first focuses on the structural features and synthetic details of all the intergrowth zeolites, especially providing some insightful discussion of several potential frameworks. Subsequently, characterization methods for intergrowth zeolites are introduced, and highlighting fundamental features of these crystals. Then, the applications of intergrowth zeolites in several of the most active areas of catalysis are presented, including selective catalytic reduction of NOx by ammonia (NH3-SCR), methanol to olefins (MTO), petrochemicals and refining, fine chemicals production, and biomass conversion on Beta, and the relationship between structure and catalytic activity was profiled from the perspective of intergrowth grain boundary structure. Finally, the synthesis, characterization, and catalysis of intergrowth zeolites are summarized in a comprehensive discussion, and a brief outlook on the current challenges and future directions of intergrowth zeolites is indicated.

One-pot rota-crystallized hollownest-structured Ti-zeolite: a calcination-free and recyclable catalytic material

A hydrothermal rota-crystallization method is developed for the one-step synthesis of a hollownest-structured zeolite precursor with the shell composed of autogenously-intergrown MWW nanosheet crystals containing a large number of stacking-pores without any porogen or hard scaffold.

A hydrothermal rota-crystallization method is developed for the one-step synthesis of a hollownest-structured zeolite precursor with the shell composed of autogenously-intergrown MWW nanosheet crystals containing a large number of stacking-pores without using any porogen or hard scaffold. This material possesses a large external surface area. By simple acid washing, the resultant Ti-containing catalyst can be directly used in the epoxidation of alkenes with hydrogen peroxide. The excellent catalytic activity over the Ti-HSZ catalyst is assumed to be due to the exposure of more Ti active sites over the MWW nanosheet crystals in the shell of the catalyst. More importantly, this Ti-HSZ catalyst washed with H₂O₂/ethanol solution has been reused 6 times without an appreciable decrease in both the conversion of the allyl chloride and the selectivity of the epichlorohydrin, which is ascribed to the structural stability of the hollownest-structured zeolite.