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This work presents a simple method for the preparation of structured Co3O4 supported on silicalite-1/SiC foam catalyst (i.e., Co@S1/SiC), and its application to catalytic combustion of volatile organic compounds (VOCs, isopropanol as the model compound). The growth mechanism of Co3O4 on silicalite-1/SiC catalysts were systematically studied as a function of synthesis time based on comprehensive characterization using N2 adsorption-desorption analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), H2 temperature programmed reduction (H2-TPR) and X-ray photoelectron spectra (XPS). It was found that Co2SiO4 nano-sheets were formed within/on silicalite-1 coating at the initial stage of synthesis, which was further transformed into flower-like Co3O4 nano crystals on the surface of silicalite-1/SiC. The developed structured catalyst, especially the one prepared by the 40 h synthesis, i.e., Co@S1/SiC-40 h, combined high oxygen mobility, Co3+/Co2+ redox couple and improved adsorbed oxygen species, and exhibited excellent performance in complete thermocatalytic combustion of isopropanol.

Catalytic carbon dioxide (CO2) methanation is a promising and effective process for CO2 utilisation and the production of CH4 as an alternative to using natural gas. Non-thermal plasma (NTP) activation has been proven to be highly effective in overcoming the thermodynamic limitation of reactions under mild conditions and intensifying the CO2 hydrogenation process greatly. Herein, we present an example of NTP-assisted catalytic CO2 methanation over Ni catalysts (15 wt%) supported on BETA zeolite employing lanthana (La) as the promoter. It was found that a NTP-assisted system presents remarkable catalytic performance in catalytic CO2 methanation without an external heat source. Significantly, the use of Na-form BETA zeolite and the addition of La (i.e. 15Ni–20La/Na-BETA catalyst) resulted in an improvement in CO2 conversions, surpassing the 15Ni/H-BETA catalyst, i.e. a seven-fold increase in the turnover frequency, TOF (1.45 s−1vs. 0.21 s−1), and selectivity towards CH4 (up to ca. 97%). In addition, the developed catalyst also exhibited excellent stability under NTP conditions, i.e. a stable performance over a 15 h longevity test (with a TOF of 1.44 ± 0.01 s−1). Comparative in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) characterisation of the developed catalysts revealed that the introduction of La2O3 to the Ni catalyst provides more surface hydroxyl groups, and hence enhances CO2 methanation. Additionally, by analysing the surface species over 15Ni–20La/Na-BETA comparatively under thermal and NTP conditions (by in situ DRIFTS analysis), it is proposed that both the Langmuir–Hinshelwood and Eley–Rideal mechanisms co-exist in the NTP system due to the presence of dissociated H species in the gas phase. Conversely, for the thermal system, the reaction has to go through reactions between the surface-dissociated H and carbonate-like adsorbed CO2via the Langmuir–Hinshelwood mechanism. The current mechanistic understanding of the NTP-activated system paves the way for the exploration of the reaction mechanisms/pathways of NTP-assisted catalytic CO2 methanation.

Background: This study aimed to analyze the bioactivity and biocompatibility of silicon carbide (SiC) foam coated with one of two kinds of zeolite. Methods: The surface charges, protein adsorption ability and mineralization ability were compared between silicalite-1/SiC foam and ZSM-5/SiC foam. Results: Proliferation and differentiation of primary osteoblasts seeded on two types of materials were significantly higher when compared with uncoated SiC foam after 7 d. There was no significant difference in the bioactivity between silicalite-1/SiC foam and ZSM-5/SiC foam. Silicalite-1/SiC foam and ZSM-5/SiC foam had no cytotoxic effect on primary osteoblasts. Conclusions: These results suggest both silicalite-1/SiC foam and ZSM-5/SiC foam have the potential for use as novel bone replacement materials.

The porosity and acidity of three commercial FAU Y zeolites (including the original HY-2.6 and dealuminated HY-15/-30 zeolites) were studied comprehensively using nitrogen (N2) physisorption, and mercury (Hg) porosimetry, ammonia temperature-programmed desorption (NH3-TPD) and pyridine Fourier transform infrared (pyridine-IR) analyses. The combined N2 physisorption and Hg porosimetry is a useful tool to evaluate the hierarchical mesoporosity in the dealuminated samples, revealing that HY-15 and HY-30 possess >50% open mesoporosity in the mesopores range of 5–10 nm. The acidity of the dealuminated Y zeolites has been reduced significantly in comparison to that of the original HY-2.6, e.g. Brønsted acidity decreased by ca. 69 folds by dealuminating HY-2.6 to HY-30. Catalytic results of Fischer esterification of methanol with carboxylic acids and aldol condensation of benzaldehyde with 1-heptanal have evidenced that the critical role of mesoporosity of the dealuminated Y zeolites in liquid-phase reactions. For example, in the esterification of lauric acid with methanol, HY-15 and HY-30 with hierarchical mesopores showed better catalytic activity (i.e. conversion of lauric acid: 7.9% and 24.5%, respectively) than HY-2.6 (4.0%). The analysis of the catalytic results along with the acidic property suggests that the acidity is less influential than the porosity of zeolite catalysts. Results from this study allow us to explain the origin of the high activity of zeolites with mesoporosity in the liquid-phase catalysis.

Adsorptive separation of ethylene/ethane (C2H4/C2H6) binary mixture has growing interest in petrochemical industries compared to the conventional energy-intensive cryogenic distillation. Development of moisture-stable materials with high selectivity is of great importance to accomplish C2H4/C2H6 separation. Coordination pillared-layer metal-organic framework (CPL-MOF) CPL-2 was synthesised at room temperature, and then modified by silver ions impregnation to enhance the selectivity towards ethylene over ethane. The synthesised CPL-2 and Ag/CPL-2 MOFs have excellent moisture stability which was confirmed by the dynamic water vapour adsorption analysis under 90% relative humidity, showing no significant framework decomposition, even at 50 °C. The calculated selectivity based on gravimetric single-component gas adsorption experiments shows the significantly improved C2H4/C2H6 selectivity from 1.4 to 26.1 after loading 10 wt.% (theoretical) of silver ions on CPL-2. Breakthrough experiments for C2H4/C2H6 (1:1, v/v) mixture suggest that both CPL-2 and 10 wt.% Ag/CPL-2 can achieve the binary mixture separation, and 10 wt.% Ag/CPL-2 shows relatively better dynamic separation performance compared to parent CPL-2. The good adsorption selectivity and moisture stability allow CPL-MOF to be a class of promising porous materials for further exploitation in the separation of C2H4/C2H6 mixtures. Additionally, the method presented here can potentially be extended to other CPLs with different pore sizes for alkene/alkane separations.

A hierarchical composite catalyst composed of a ZSM-5 coating on SiC nano-whiskers that grew on SiC foam supports was designed and synthesized to simultaneously improve the zeolite loading and mass transfer of both the reactants and products in the methanol-to-propylene (MTP) reaction. SiC nano-whiskers were first grown on SiC foam supports by a chemical vapor deposition method to construct a hierarchical porous structure on the struts. ZSM-5 type zeolite crystals with high coverage were then hydrothermally grown on the SiC nano-whiskers after their surface was properly modified with zeolite precursor gel. In this way, the mass loading of the zeolite coating and mass transfer property, the two key factors that hinder the catalytic properties of the ZSM-5/SiC foam composite reported in our previous work, were enhanced, which in turn substantially improved the stability and selectivity of the obtained ZSM-5/SiC nano-whisker/SiC foam composites in MTP reaction as compared with those of the ZSM-5/SiC foam composites and ZSM-5 pellets.

A post-synthesis method was developed to reduce the extra-framework titanium (Ti) in TS-1 zeolites (Si/Ti ratio = 50), in which tetrapropylamonium hydroxide (TPAOH) aqueous solution was used to promote the dissolution, redistribution and recrystallization processes, and hence to convert amorphous Ti species into zeolitic phases. It was found that TPAOH could effectively convert the extra-framework Ti into framework Ti, and the TPAOH concentration influenced the pore structure significantly. Under lower TPAOH concentration (i.e. 0.05–0.4 M), only closed meso-/macropores (grooves and hollow cavities) can be created in the TS-1 crystals. At an optimum concentration of 0.5 M TPAOH, open and connected hierarchical mesopores and macropores were created in the resulting TS-1 zeolites. Compared with the parent TS-1, the amount of extra-framework titanium was reduced significantly from 14.4% to 0.3% and the meso-/macropore volume was increased from 0.014 to 0.168 cm3 g−1 accordingly upon TPAOH post treatment. Along with the parent TS-1 zeolite, the developed hierarchical TS-1 zeolites were assessed in the catalytic epoxidation of cyclohexene. It was confirmed that the amount of framework titanium and hierarchical pore structure influenced the catalytic activity considerably. Closed porosity slightly improved the cyclohexene conversion, whereas the open-pore sample shows the optimum catalytic activity in cyclohexene conversion.

Osteointegration is crucial for success in orthopedic implantation. In recent decades, there have been numerous studies aiming to modify titanium alloys, which are the most widely used materials in orthopedics. Zeolites are solid aluminosilicates whose application in the biomedical field has recently been explored. To this end, MFI zeolites have been developed as titanium alloy coatings and tested in vitro. Nevertheless, the effect of the MFI coating of biomaterials in vivo has not yet been addressed. The aim of the present work is to evaluate the effects of MFI-coated Ti6Al4V implants in vitro and in vivo. After surface modification, the surface was investigated using field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). No difference was observed regarding the proliferation of MC3T3-E1 cells on the Ti6Al4V (Ti) and MFI-coated Ti6Al4V (M-Ti) (p > 0.05). However, the attachment of MC3T3-E1 cells was found to be better in the M-Ti group. Additionally, ALP staining and activity assays and quantitative real-time RT-PCR indicated that MC3T3-E1 cells grown on the M-Ti displayed high levels of osteogenic differentiation markers. Moreover, Van-Gieson staining of histological sections demonstrated that the MFI coating on Ti6Al4V scaffolds significantly enhanced osteointegration and promoted bone regeneration after implantation in rabbit femoral condylar defects at 4 and 12 weeks. Therefore, this study provides a method for modifying Ti6Al4V to achieve improved osteointegration and osteogenesis.

Highly accessible porous ZSM-5 coating with high loading and high adherence was successfully grown on SiC foam support using a two-step coating and steam-assisted crystallization process. The zeolite precursor gel pre-coated on the SiC foam surface and existed in the upper mixed coating layer functioned as a binder to firmly bond the SiC support and the pre-coated zeolite crystals with the formation of a dense ZSM-5 transition layer. The high porosity was achieved from the pre-coated zeolite crystals. The ZSM-5/SiC foam composite catalyst prepared by the proposed method showed higher propylene selectivity and propylene to ethylene (P/E) ratio, lower C1–C4 saturated hydrocarbons and aromatics and as well as higher stability in comparison to that prepared by conventional in situ hydrothermal process in methanol to propylene reaction.

ZSM-5 coatings with controllable morphology, Si/Al ratio, and loading were grown on SiC foam support with zeolite precursor modified surface. A homogeneous coverage of the support (15 wt.% zeolite) by ZSM-5 crystals with an average crystal size of about 3.5 mu m was reached by controlling the amount of NaCl and TPAOH. The surface modification by the zeolite precursor gel layer ensured the strong anchoring and the loading of the zeolite crystals on the SiC support. The ZSM-5/SiC foam composite catalyst showed substantial stability and yield improvement in comparison to zeolite pellets in the methanol to propylene (MTP) reaction. (C) 2012 Elsevier Inc. All rights reserved.

Silicalite-1 (S1) foam was functionalized by supporting manganese–cobalt (Mn–Co) mixed oxides to develop the structured hierarchical catalyst (Mn–Co@S1F) for catalytic combustion for the first time. The self-supporting S1 foam with hierarchical porosity was prepared via hydrothermal synthesis with polyurethane (PU) foam as the template. Subsequently, Mn–Co oxide nano sheets were uniformly grown on the surface of S1 foams under hydrothermal conditions to prepare the structured hierarchical catalyst with specific surface area of 354 m2·g−1, micropore volume of 0.141 cm3·g−1 and total pore volume of 0.217 cm3·g−1, as well as a good capacity to adsorb toluene (1.7 mmol·g−1 at p/p0 = 0.99). Comparative catalytic combustion of toluene of over developed structured catalyst Mn–Co@S1F was performed against the control catalysts of bulk Mn–Co@S1 (i.e., the crushed Mn–Co@S1F) and unsupported Mn–Co oxides (i.e., Mn–Co). Mn–Co@S1F exhibited comparatively the best catalytic performance, that is, complete and stable toluene conversion at 248 °C over 65 h due to the synergy between Mn–Co oxides and S1 foam, which provided a large number of oxygen vacancies, high redox capacity. In addition, the hierarchical porous structure also improved the accessibility of active sites and facilitated the global mass transfer across the catalyst bed, being beneficial to the catalysis and catalyst longevity.

This work presents the development and systematic study of a method to prepare hierarchical titanium silicalite-1 (TS-1) zeolites with high tetra-coordinated framework Ti species content. The new method involves (i) the synthesis of the aged dry gel by treating the zeolite precursor at 90 °C for 24 h; and (ii) the synthesis of hierarchical TS-1 by treating the aged dry gel using tetrapropylammonium hydroxide (TPAOH) solution under hydrothermal conditions. Systematic studies were conducted to understand the effect of the synthesis conditions (including the TPAOH concentration, liquid-to-solid ratio, and treatment time) on the physiochemical properties of the resulting TS-1 zeolites, and the results showed that the condition of a TPAOH concentration of 0.1 M, liquid-to-solid ratio of 1.0, and treatment time of 9 h was ideal to enable the synthesis of hierarchical TS-1 with a Si/Ti ratio of 44. Importantly, the aged dry gel was beneficial to the quick crystallization of zeolite and assembly of nanosized TS-1 crystals with a hierarchical structure (Sext = 315 m2 g–1 and Vmeso = 0.70 cm3 g–1, respectively) and high framework Ti Species content, making the accessible active sites ready for promoting oxidation catalysis.