Controlled release of siliceous species for the fabrication of highlyb-oriented MFI zeolite films

Abstract

Silicate precursor nanoparticles are complexed with 1,2-dihydroxybenzene and then gradually released to feed the secondary growth of b-oriented MFI zeolites.

Twin suppression effect of dihydroxy-benzene isomers during the secondary growth of b-oriented zeolite MFI nanosheet films

“…The decrease was the fastest for 1,2-C 6 H 6 O 2 , followed by 1,3-C 6 H 6 O 2 , and the slowest for 1,4-C 6 H 6 O 2 . This is consistent with the inhibitory effect of C 6 H 6 O 2 addition on the twin growth of seeds (see Fig.1and our previous result33 ). That is to say, reducing the growth rate of the seed crystal can effectively inhibit the growth of twin crystals, and the greater the reduction of the seed crystal growth rate, the stronger the effect of suppressing the growth of twin crystals.…”

“…A film formation mechanism based on controlled nutrient release in the presence of 1,2-C 6 H 6 O 2 was proposed in a previous work. 33 1,2-C 6 H 6 O 2 was considered to be a chelating agent, which by complexing with the silicate precursor nanoparticles (PNs) reduces their reactivity and suppresses the formation of twin crystals. The formation of a sixcoordinate silicon-1,2-C 6 H 6 O 2 complex was confirmed by the liquid-state 29 Si-NMR characterization.…”

“…We previously reported 33,34 ) can also succeed in eliminating twins, and to determine the applicability of this approach for the fabrication of thin MFI nanosheet films. In this communication, we investigated and compared the twin suppression effect of dihydroxybenzene isomers during secondary growth.…”

“…38 It has been confirmed that the film orientation would be randomized in the presence of the TPA + template during synthesis, and then the twin suppression technique of adding a chelating agent of 1,2-C 6 H 6 O 2 was established. 33,34 Here, we added 1,3-C 6 H 6 O 2 and 1,4-C 6 H 6 O 2 into the synthesis mixtures to make homogeneous mixtures with molar composition of 0.2TPAOH : 1TEOS (tetraethylorthosilicate) :…”

Single‐Mode Microwave Heating‐Induced Concurrent Out‐of‐Plane Twin Growth Suppression and In‐Plane Epitaxial Growth Promotion of b‐Oriented MFI Film under Mild Reaction Conditions

“…Recent decades have witnessed great efforts on the preparation of b ‐oriented MFI films with few twins . Diverse methods like multi‐mode microwave heating, precursor solution pretreatment, employing specifically designed template ( trimer ‐TPAOH), vapor phase transformation, solvent‐free epitaxial growth and additive addition (like ammonia salts, sodium tungstate and 1,2‐dihydroxybenzene) have proven effective for twin suppression.…”