High-throughput synthesis and catalytic properties of a molecular sieve with 18- and 10-member rings

Abstract

Crystalline molecular sieves with large pores and high adsorption capacities have many potential applications. Of these materials, zeolites are of particular interest owing to their stability in a wide range of experimental conditions. An aluminophosphate with very large circular channels(5) containing 18 oxygen atoms (18-ring channels) has been synthesized, but in the search for large-pore zeolites, most of the materials which have been synthesized up to now contain only 14-ring channels; the synthesis of zeolites with larger ring structures has been believed to be hindered by the low Si-O-Si bond angles available. A silicogaloaluminate (ECR-34) with unidirectional 18-ring channels was recently reported, but exhibited low micropore volume, thus rendering the material less attractive for catalytic applications. Here we report the structure and catalytic activity of the silicogermanate zeolite ITQ-33; this material exhibits straight large pore channels with circular openings of 18-rings along the c axis interconnected by a bidirectional system of 10-ring channels, yielding a structure with very large micropore volume. The conditions for synthesis are easily accessible, but are not typical, and were identified using high-throughput techniques.

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

“…The synthesis processes of sodium bis(oxalato)borate (NaBOB), hydrogen bis(oxalato)borate (HBOB) and 1-alkyl-3-methylimidazolium bis ( 4 (85%) were charged into a 15 ml Teflon-lined stainless steel autoclave directly. The vessel was heated under autogenous pressure at 160°C for 5 days, and then cooled to room temperature.…”

“…For example, the synthesis of silicate zeolites with larger ring structures has been believed to be hindered by the low Si-O-Si bond angles available. To the best of our knowledge, the upper-limit of pore size for silicate remains 18-ring [4], the maximum pore dimension of phosphate is 24-ring [9], that of phosphite reaches to 26-ring [8], while the largest pore size of germanium oxide has been expanded to mesoporous range with 30-ring channel structure [10,11].…”

“…Surprisingly, the report on extra-large microporous borophosphate is quite few. Up to now, the only example known is a vanadium borophosphate in which connections of VO 6 octahedra, PO 4 and BO 4 tetrahedra, and BO 2 (OH) trigonal planes form intersecting 8-, 12-and 16-ring channels [15]. How to synthesize extra-large microporous borophosphate still keeps challenging.…”

“…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].…”

Pure silica ITQ-32 zeolite allows separation of linear olefins from paraffins

“…1 Therefore, adsorption processes that are able to discriminate between olefins and paraffins are of great interest in this area and have been investigated in the last years. 2 Besides the 20 interest in the synthesis of ultralarge pore zeolites for catalysis, electronics and drug delivery, [3][4][5][6] a number of zeolites with small pores have been reported for olefin/paraffin separations, including Cu and/or Ag exchanged zeolites 7 and neutral all-silica [8][9][10][11] or aluminophosphate molecular sieves. 12, 13 Cu and Ag-exchanged 25 materials accomplished the gas separation process through π-complexation interaction cation-olefin, 14 while in the case of neutral zeolites and aluminophosphates the separation is based in a molecular sieve effect, 15 which presents clear benefits in terms of stability and long term operation with respect to cation-exchanged 30 zeolites.…”