Cubic Pm3n mesoporous aluminosilicates assembled from zeolite seeds as strong acidic catalysts

Abstract

Cubic Pm3n mesoporous aluminosilicate isomorphous to SBA-1 with 3D-interconnected pore structures was assembled by Al-incorporated zeolite seeds at pH around 9 using cetyltriethylammonium bromide as pore-directing agent. The resultant materials (termed Al-ZSBA-1) owned the advantages of strong acidity from zeolitic structures and good diffusivity of bulky reactants from 3D-interconnected mesopores. Al-10 ZSBA-1 with Al loading up to a Al/Si molar ratio of 0.057 still retained the cubic Pm3n structure and high surface areas (ca. 600 m 2 /g). Their acidities were stronger than the counter materials prepared using sodium silicate as the silica source (referred as Al-SBA-1-alk). Moreover, all the Al(III) ions in Al-ZSBA-1 retained in tetrahedral coordination after calcination at 823 K, while a portion of Al(III) in Al-SBA-1-alk became octahedrally coordinated. In application to catalytic alkylation of 2,4-di-tert-15 butylphenol with cinnamyl alcohol, Al-ZSBA-1 gave higher flavan selectivities and yields, in comparison to Al-SBA-1-alk, ZSM-5, and beta zeolites. 45 (IZA code MWW) is the first identified zeolite formed by vertically aligning lamellar zeolite intermediate. 31 The as-made MCM-22 precursor (MCM-22(P)) is the stacking of zeolitic sheets through hydrogen bond and organic template with repeating unit d (001) of 2.5 nm. Several methods such as 50 calcination, delamination, swelling and pillaring have been applied to MCM-22(P) in order to generate micro/meso-porous structures namely MCM-56, MCM-36 and ITQ-2 in the past two decades. 32,33 However, the mesopores generated by pillaring or exfoliation of MCM-22(P) have wide distributed pore diameters. 55 Recently, Ryoo's group designed a series of gemini-type, polyquaternary ammonium surfactants which could generate micropores and mesopores simultaneously, and ordered mesoporous structures (lamellar or hexagonal) with thin zeolitic walls were synthesized based on the dual-templating concept. 30,34 60 The drawbacks are the tedious procedure and cost in synthesizing the specially designed surfactants.Among the mentioned methods, method (ii) using zeolite seeds as the building units of mesoporous framework has shown the advantage of facile control of the mesostructure through changing 65 different kinds of surfactants and hydrothermal conditions. The Graphical AbstractCubic Pm3n mesoporous aluminosilicate with 3D interconnected pore structure, assembled with Al-incorporated ZSM-5 seeds at pH 9 using CTEABr as pore-directing agent, was an efficient catalyst in alkylation of 2,4-di-tert-butylphenol with cinnamyl alcohol to form flavan.

Water electrolysis for hydrogen production: from hybrid systems to self-powered/catalyzed devices

“…368,369 However, their high cost and partially unfavorable electrocatalytic properties have motivated the exploration of nonnoble metal-based catalysts. 370,371 Consequently, diverse electrocatalysts have been developed, including porous MoO 2 -FeP@C, 372 CoO-CoSe 2 , 373 CoP, 374 nanocrystalline Cu, 375 Ni 3 S 2 /NiF, 376 Ni/Co/Fe-OOH, 377 mesostructured NiO, 378 Ni NSs, 379 NiFe-LDH, 380 NiCoFe-LDH, 381 NiCoMn-LDHs, 382 corallinelike CoP/Ni 2 P-NiCoP@NC, 383 Co-CoS x heterojunctions, 384 CoOOH, 385 Ni 3 N-V 2 O 3 , 386 NiO x /NF, 387 NiMoO-Ni, 388 Cu doped Co 3 O 4 nanowires, 389 branched Ni NPs, 390 Ni x B, 391 NiS x /Ni 2 P nanotube arrays, 392 NiCo 3 O 4 NWs, 393 NiCo 2 @MoO 2 /NF, 394 CuNi(OH) 2 , 395 and (FeCrCoNiCu) 3 O 4 NSs. 396 The catalytic conversion of HMF to FDCA requires the oxidation of both the alcohol and aldehyde groups in HMF.…”

Synthesis, Characterization and Use of Mesoporous Silicas of the Following Types SBA-1, SBA-2, HMM-1 and HMM-2

“…Lin et al [ 70 ] have undertaken the synthesis of SBA-1 modified with aluminum ions in basic conditions, using a zeolite modified with aluminum as a precursor of silicon and aluminum (zeolite Al-ZSM-5). The obtained SBA-1 silicas modified with that zeolite and aluminum ions showed highly-ordered pore structure as proved by the three reflections in the XRD diffractograms in the range of small 2θ, corresponding to the planes (200), (210) and (211), characteristic of Pm n symmetry.…”

“…The obtained silicas proved to be effective catalysts in Friedel-Crafts alkylation of 2, 4-Di- tert -butylphenol with cinnamyl alcohol. The catalysts obtained were noted to combine the benefits of zeolites (strong acidity) and mesoporous materials (diffusion of reagents) [ 70 ].…”