Extra‐Large‐Pore Zeolites: Bridging the Gap between Micro and Mesoporous Structures

Abstract

The conditions required to produce zeolites with low framework density and extra-large pores are discussed. Correlations between framework stability and geometrical and topological descriptors are presented. An attempt has been made to rationalize the synthesis of extra-large-pore zeolites in terms of the synthesis mechanism, the directing effect of the organic structure directing agent (OSDA), the framework atoms, and the gel concentration. Extra-large-pore zeolites, including the recently discovered chiral mesoporous ITQ-37, are described and their catalytic and adsorption properties discussed. Finally, strategies are presented for the preparation of extra-large-pore zeolites with different pore topologies that can fulfill pre-established catalytic and adsorption targets.

Role of boron-containing ionic liquid in the synthesis of manganese borophosphate with extra-large 16-ring pore openings

“…In particular, the extra-large microporous solids with pore openings larger than 12-rings are highly desirable for their unique application in large molecules involved processes [3,4]. Considerable efforts have been made to synthesize various extra-large microporous materials, and some effective synthetic strategies including the use of large and rigid templates [5], the selection of framework elements favoring the formation of 3-and 4-rings [6], and the replacement of PO 3À 4 tetrahedra by HPO 2À 3 pyramidal phosphite units to reduce the M-O-P linkages so as to generate more-open interrupted frameworks have been developed [7,8].…”

Mesostructured Zeolites: Bridging the Gap Between Zeolites and MCM-41

“…In addition, there have been efforts to alleviate the diffusion limitations through a synthesis of extra-large-pore molecular sieves (e.g., ITQ-21, ITQ-37 and ITQ-40) View Article Online using organic structure directing agents (SDAs). 24,69,70 Corma et al exhibited that the synthesized materials can contain large pore openings (i.e., up to 16-member rings) or large cavities (i.e., 1.8 nm-wide). The results from catalytic cracking of a vacuum gas oil show that the activity of ITQ-21 is higher than that of the USY zeolite, but it produces a lower gasoline yield.…”

A New Microporous Zeolitic Silicoborate (ITQ-52) with Interconnected Small and Medium Pores

“…Zeolites have been applied for gas adsorption, separation, catalysis, encapsulation or controlled release of molecules, among others, some of them are of industrial application. [1][2][3][4][5][6][7][8][9] There is no doubt that this is the driving force for synthesizing new zeolite structures.…”

“…Zeolites have been applied for gas adsorption, separation, catalysis, encapsulation or controlled release of molecules, among others, some of them are of industrial application. [1][2][3][4][5][6][7][8][9] There is no doubt that this is the driving force for synthesizing new zeolite structures.Most of the zeolites described in the literature have been obtained by employing tetraalkylammonium cations as organic structure directing agents (OSDAs). 10-13 Recently, we have reported a number of new zeolites synthesized by using tetraalkylphosphonium cations 14 15 and ITQ-49 17 ) or phosphazenes (ITQ-47 18 ) as OSDAs.…”

“…The second unit, with a ring notation [4 2 5 4 6 1 ], contains 13 T-atoms, and it was only observed before in zeolite SSZ-23 (IZA code STT). 33 Finally, the last one consists of 58T-atoms forming a large cavity ([4 8 5 8 6 8 8 4 10 2 ]), accessible through two 10R and four 8R apertures (Figure 2). Each large cage in ITQ-52 is connected to six neighbor similar cavities, either through one 8-or one 10-ring window, sharing the corresponding T-atoms.…”