Interzeolite Transformations as a Method for Zeolite Catalyst Synthesis

Abstract

This review presents the achievements of the last 10-15 years in interzeolite transformations as a method for synthesizing high-performance zeolite catalysts. The main regularities and mechanisms of interzeolite transformations are analyzed. The paper describes a variety of examples where interzeolite transformations ensured a successful synthesis of zeolite structures which either could not be prepared from amorphous sources or required the use of expensive templates. The advantages of zeolite catalysts synthesized by interzeolite transformation, compared to those obtained from amorphous sources, are demonstrated.

Hierarchical Catalysts Prepared by Interzeolite Transformation

“…As evidenced by TEM, the interconversion of FAU into BEA undergoes through an amorphous phase, from which BEA nanocrystals develop. As described by Ivanova et al, 39 interzeolite transformations can proceed through two mechanisms: (1) a solid → solid transformation (from amorphous to crystalline) and (2) a solution-mediated mechanism involving the dissolution of the initial phase. On the basis of our data, we speculate that a combination of these two methods occurs during the transformation of FAU into BEA.…”

On the key role of aluminium and other heteroatoms during interzeolite conversion synthesis

“…In line with the recent review of Bruter et al , 56 the following questions regarding IZC understanding remain unanswered:…”

“…Overall, the current state of the art investigations on IZC mechanisms are insufficient to conrm 'nanoparts', let alone capture their role in IZC, in line with other IZC review papers. 4,56 It would be interesting to experimentally detect the role of Al in oligomerization. Also, some computational studies exist, such as those on LTA formation demonstrating the (theoretical) construction of D4R from dimeric aluminosilicates (Si(OH) 3 -O-Al(OH) 3 À ) as a rst step to LTA (Si/Al ¼ 1).…”

“…In such cases, with no more than 4% of T-atoms in solution, 141 it is virtually impossible to correlate pre-existing species ( X ) to growth (see 3.3) as one is not able to distinguish structural elements present within crystalline parent or daughter zeolites from the contribution of independent growth units. 56 The same experimental set-up should also be performed at synthesis conditions with at least 50% of the T-atoms dissolved ( i.e. at higher Si/Al) for clear experimental observation of potential structural growth units.…”

Controlling Nucleation Pathways in Zeolite Crystallization: Seeding Conceptual Methodologies for Advanced Materials Design

“…There have been several review articles written on topics of SAS, IZT, and zeolite synthesis that provide in-depth descriptions of synthesis techniques, material properties, and zeolite performance in different applications. − In this Perspective, we provide a conceptual overview of SAS pathways and highlight recent breakthroughs in the use of seeds to achieve novel materialsnotably nanosized and hierarchical zeolites. Within the context of seed-assisted methods, we provide a synopsis of IZT and propose ways to explain (or potentially predict) trends in nucleation under different synthesis conditions.…”