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Abstract: Freestanding blocks of binary oxides, TiO2–SiO2 aerogel containing highly ordered mesophase structures were successfully prepared by a new synthesis method involving partial solvent evaporation followed by supercritical extraction and drying. The new method allows the routine preparation of large, crack-free aerogels of high titanium content (i.e., Ti/Si⩽0.75 or up to 50wt.% Ti), ordered mesopores (i.e., 2–20nm), large surface area (i.e., 400–900m2 g−1) and pore volume (i.e., 0.7–2.6cm3 g−1). Aerogels with well-ordered mesopores were obtained for Ti/Si atom ratios of 0.04–0.08. The size of ordered mesopore domains decreases with increasing titanium loading, and TS75 aerogels with Ti/Si=0.75 display discontinuous microdomains of ordered mesoporosity within disordered phases interspersed with crystalline anatase TiO2. The greater permeability of the TS75 pore network resulted in fifteen times better activity for photocatalytic oxidation of airborne trichloroethylene compared to commercial Degussa P25 TiO2 and more than twice that TiO2–SiO2 aerogel (TS100) of similar titanium loading but with disordered and tortuous pore network. [Copyright &y& Elsevier]

Abstract: Sn-Beta zeolites were prepared by a rapid and clean steam-assisted conversion (SAC) method from dry stannosilicate gel. The amorphous gel was converted to highly crystalline Sn-Beta within 5h at mild reaction temperature of 453K. The properties of the as-prepared samples were characterized by XRD, SEM, FT-IR, UV–Vis, UV-Raman, ICP and N2 adsorption. A high gel conversion to BEA can be obtained with Sn4+ inserted in the zeolite framework. The SAC method was successfully used to produce pure silica Beta zeolite (Si/Sn=∞) to Sn-Beta zeolite with 3.8wt.% SnO2 (i.e., Si/Sn=83). The Sn-Beta prepared by SAC method is an efficient catalyst for Baeyer–Villiger (B–V) reaction of cyclohexanone to ε-caprolactone. [Copyright &y& Elsevier]

Abstract: Pd membrane reactor for one-step hydroxylation of benzene to phenol was investigated in an effort to reconcile the contradicting reports in the literature. A systematic study of the membrane, reactor and feed mode was conducted. Reactions carried out on Pd-TS-1 and Pd capillary membranes support Niwa''s postulate of in situ hydrogen peroxide formation, but at the same time indicate that reactive species generated by reactions between permeated hydride ions and activated oxygen also participate in the reaction. The former reaction is important at low benzene feed concentrations and for reactors with small membrane area-to-reactor volume ratios. TS-1 catalyst in Pd-TS-1 membrane can significantly improve the yield and selectivity to phenol. High benzene feed concentrations and faster mass transfer gives the reactive species greater opportunity to react directly with benzene resulting in high benzene conversion but poor selectivity. [Copyright &y& Elsevier]

Abstract: An advanced ozone membrane reactor that uses membranes for ozone distribution, reaction contact and selective water separation was used for ozone treatment of a recalcitrant endocrine disrupting compound in water. Experiments and model calculation were employed to examine the ozonation of phthalate in the new reactor. Experimental results showed that fast ozone mass transfer rate is responsible for membrane reactor''s superb performance compared with a semibatch reactor. Selective water removal further enhanced phthalate conversion and TOC removal by concentrating the pollutants in the reaction zone. Clean water was produced by membrane separation. Mathematical model was used to investigate the effect of membranes, reactor design and reaction operation on pollutant conversion and removal. [Copyright &y& Elsevier]

Abstract: Alkali-resistant Ni/SiO2–Sil-1 and Ni/Al2O3–Sil-1 core–shell catalysts were prepared for use in direct internal reforming molten carbonate fuel cell (DIR-MCFC). A thin zeolite shell was grown on the surface of catalyst beads to create a diffusion barrier against alkali poisons in the vapors generated from the electrolyte during DIR-MCFC operation. The synthesis of low defect zeolite shell was investigated and the effects of shell thickness on catalyst activity were examined. A mathematical model of the reaction and alkali-poisoning was developed and the optimum zeolite shell thickness was determined. The experimental and modeling results demonstrated that the core–shell catalyst is more resistant to alkali poisoning and a zeolite shell thickness of 3.5μm can protect the catalyst for at least 100h following a failure of the anode barrier in DIR-MCFC to give sufficient time for repair. [Copyright &y& Elsevier]

Abstract: A monolayer of zeolite nanoparticles was deposited uniformly on SiO2 beads’ surface by a new seeding method based on the combined use of organic linker and dip-coating procedure. The seeds were transformed into a well-intergrown TS-1 zeolite film and characterizations by SEM and XRD indicated that the film has a preferred (011) orientation. EDXS, XPS and UV–vis spectroscopies confirmed the successful preparation of egg-shell TS-1/SiO2 catalysts. Thin shell catalysts (i.e., <11μm) were more active for styrene oxidation. Conversion reaction rate of 8.9mmolg−1 h−1 and turnover frequency of 28h−1 were obtained with aromatic aldehydes (i.e., benzaldehyde and phenyl acetaldehyde) being the main products. Greater mass transfer resistance made thick shell catalysts less efficient with lower specific conversion rate of 6.9mmolg−1 h−1 and turnover frequency of 25h−1. Also, the extra-framework titanium resulting from the longer synthesis led to poorer selectivity. Egg-shell TS-1/SiO2 catalyst beads were shown to be resistant to attrition and were easier to separate and recover from reaction. [Copyright &y& Elsevier]

Abstract: Titanium silicalite-1 (TS-1) zeolites and films supported on porous α-Al2O3 tubes were prepared using TS-1 and silicalite-1 (Sil-1) seeds by hydrothermal synthesis. The structure and catalytic properties of the TS-1 powders and films were characterized by SEM, XRD, FT-IR, UV–vis and styrene partial oxidation by hydrogen peroxide. The results showed that TS-1 prepared from Sil-1 seeds were as active as TS-1 from nucleated and TS-1 seeded syntheses, in spite of the concerns about nonuniformity and dilution caused by the use of pure silica Sil-1 seeds. The Ti atoms were successfully incorporated as tetra-coordinated titanium in the zeolite framework and the phenylacetaldehyde selectivity correlates well with the infrared band for Ti–O–Si of the TS-1. Reaction over TS-1 film indicates that reactions occurred at the topmost layer of the film due to the slow diffusion in the zeolite pores. [Copyright &y& Elsevier]