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A series of dealuminated HMCM-68 zeolites were prepared by treatment with steaming or hydrochloric/citric acid leaching. Their catalytic properties were studied using the alkylation of phenol with tert-butyl alcohol as a test reaction. The HMCM-68 zeolite modified by citric acid for 8 h (CAZ8) showed the best catalytic performance due to its improved structural and acidic properties, confirmed by methods of XRD, ICP-AES, SEM, N 2 -adsorption, 27 Al MAS NMR and NH 3 -TPD. Furthermore, it is proposed that citric acid treatment is the most suitable method for dealumination of HMCM-68 zeolite in the alkylation of phenol, which results in the zeolites having improved adsorption polarity, as well as enlarged surface area and pore volume for the desired transformation. The factors affecting the reaction over CAZ8 have also been extensively investigated. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mn-MCM-41 has been prepared by different synthetic routes. [•] The structure of the catalysts confirmed by different physico-chemical techniques. [•] Mn-M41-K of catalysts exhibited high activity for selective epoxidation of styrene. [•] The MnO x dispersed in channels of Mn-M41-K did almost not leach and could be recyclable. [•] One possible reaction mechanism is proposed. [Copyright &y& Elsevier]

Highlights: [•] External surface passivated SBA-15 was applied to support chiral Ir(I) catalyst. [•] Notably higher ee values than the homogeneous catalyst were obtained. [•] Passivated support was better than the nonpassivated material. [•] Passivated SBA-15 based catalyst could be easily recycled. [Copyright &y& Elsevier]

Abstract: Carboxyl-modified mesoporous materials have been demonstrated as efficient carriers for immobilizing enzymes. However, little attention has been paid to the effect of H2SO4 treatment, a key in the synthesis of carboxyl-modified carriers, on the immobilization. To examine the H2SO4 treatment’s influence, we contrasted the ability of immobilizing papain between SBA-15 and the one after H2SO4 treatment (H2SO4-treated SBA-15). Meanwhile, the contribution of the as-synthesized carboxyl to the immobilization was also rechecked by comparing carboxyl-modified SBA-15 (COOH-SBA-15) and H2SO4-treated SBA-15. In relation to the experiments, the H2SO4 treatment increases the immobilizing ability of SBA-15, especially when the immobilization performs near the pI of papain. Moreover, the as-synthesized carboxyl facilitates the immobilization by means of strengthening the hydrophobic dehydration at the interface, instead of merely through electrostatic forces. Additionally, the carboxyl makes a large contribution to inducing the favorable conformation change of papain, improving the specific activity, catalytic efficiency, and binding affinity of the immobilized enzyme when combined with the substrate. [Copyright &y& Elsevier]

Abstract: The 3-aminopropyl-functionalized mesoporous materials with various amounts of 3-aminopropyl groups and nanopore sizes were synthesized through direct co-condensation of tetraethoxysilane with 3-aminopropyltriethoxysilane (APTES) using alkyltrimethylammonium bromide as template and applied to immobilize chiral Mn(III) salen complex. All the mesoporous hybrids and heterogeneous catalysts had ordered hexagonal mesostructure with uniform pore size distributions. The obtained heterogeneous catalysts exhibited comparable conversion and enantiomeric excess to those of the homogeneous counterpart for the asymmetric epoxidation of olefins even with a very low catalyst dosage (0.6mol%), which were thrice more active than the catalysts supported on the 3-aminopropyl graft-modified mesoporous silicas. The improved catalytic efficiency was mainly attributed to the homogeneous distribution of chiral Mn(III) salen complexes on the surface of co-condensation modified supports. Both the APTES dosage and nanopore size of mesoporous hybrid material were found to have great influences on catalytic performance, and the catalyst with suitable APTES content and larger pore size showed higher catalytic activity and enantioselectivity. [Copyright &y& Elsevier]

Abstract: 3-Aminopropyltriethoxysilane modified mesoporous SBA-15 was used to load the NiBr2(PPh3)2 as a heterogeneous catalyst for the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) when initiated by ethyl 2-bromoisobutyrate (EBriB) in toluene. Due to the Lewis acid sites formed by the surface silanol groups of the mesoporous material, some monomer conversions were much higher even than that catalyzed by the homogeneous catalyst NiBr2(PPh3)2 under the same reaction conditions while polydispersity indices (PDI) of the products still kept narrow (1.20–1.30). At the same time, the activity of the catalyst could be modulated by changing the quantity of the –NH2, SBA-15 and the free PPh3. In the recycling experiments, the recovered heterogeneous catalyst basically maintained its catalytic activity without any addition of new heterogeneous catalyst. [ABSTRACT FROM AUTHOR]

Novel hierarchical MCM-68 zeolite materials were successfully prepared by two simple, effective and environmentally friendly methods: H 2 O 2 microexplosion under microwave and NH 3 (aq) treatment. The characterization of the materials with powder XRD, SEM, TEM, N 2 -sorption, and NH 3 -TPD proved that abundant mesopores across zeolite crystals were created while the microporous MSE framework was well preserved. The mesopore volume of hierarchical MCM-68 zeolites is up to 0.19 cm 3 g −1 . The crystallinities of hierarchical ones and microporous MCM-68 are nearly the same according to the XRD result. The acidities of hierarchical MCM-68 are generally lower than their raw materials. Gas-phase isomerization reaction of m -xylene was carried out over these hierarchical MCM-68 zeolites as well as HMCM-68 zeolite under different conditions to characterize the catalytic property of newly prepared hierarchical zeolites. It was found that the m -xylene conversion and disproportionation/isomerization rate ratio were closely related to the created mesopores in hierarchical MCM-68 zeolites under high reaction temperature and low weight hourly space velocity (WHSV). Moreover, these hierarchical MCM-68 zeolites exhibited improved resistance to coke formation compared with HMCM-68. [ABSTRACT FROM AUTHOR]