7 results on '"Abdul-Lateef Adedigba"'
Search Results
2. The effect of T-atom ratio and TPAOH concentration on the pore structure and titanium position in MFI-Type titanosilicate during dissolution-recrystallization process
- Author
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Micheal Perdjon, Graham J. Hutchings, Yilai Jiao, Abdul-Lateef Adedigba, Jinmin Liu, Nicholas Dummer, Yangtao Zhou, Hengyu Shen, and Yanan Guan
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Materials science ,Cyclohexene ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Microporous material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Mechanics of Materials ,Hydroxide ,General Materials Science ,Orthorhombic crystal system ,0210 nano-technology ,Mesoporous material ,Dissolution ,Monoclinic crystal system ,Titanium - Abstract
In this work, titanosilicate MFI (TS-1) crystals with different Si/Ti ratio were treated with tetrapropylamonium hydroxide (TPAOH) solution of different concentrations. The results showed that the properties – crystal structure, titanium position, secondary pore structure and volume – of the treated samples strongly depend on the Si/Ti ratio of the parent TS-1 sample and the TPAOH concentration. For instance, high TPAOH concentration is necessary to induce titanium re-insertion into framework position and to create inter-connected open meso/macropore in TS-1 with low Si/Ti ratio. On the contrary, TPAOH treatment even at high concentration was found to be ineffective in the post-synthesis treatment of low titanium containing TS-1 samples and result in a phase change from orthorhombic to monoclinic. The post-treated high titanium containing and inter-connected secondary pore TS-1 samples exhibited higher activity for cyclohexene epoxidation than the parent TS-1 sample with similar Si/Ti. This technique provides a controlled way of mesopore creation in TS-1 materials, which may be extended to other titanium base microporous materials.
- Published
- 2020
3. On the synthesis and performance of hierarchical nanoporous TS-1 catalysts
- Author
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Armando Borgna, Abdul-Lateef Adedigba, Shibo Xi, Gopinathan Sankar, C. Richard A. Catlow, and Yonghua Du
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Materials science ,Inorganic chemistry ,Cyclohexene ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Catalysis ,law.invention ,Chitosan ,chemistry.chemical_compound ,Crystallinity ,law ,QD ,General Materials Science ,Calcination ,Zeolite ,Nanoporous ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,chemistry ,Chemical engineering ,Mechanics of Materials ,0210 nano-technology ,Titanium - Abstract
Hierarchical TS-1 zeolite was successfully prepared using chitosan as a sacrificial template. The X-ray diffraction showed that the presence of chitosan with the synthesis precursor had no deleterious effect on the crystallinity and phase purity of this zeolite. X-ray absorption spectroscopy at the Ti K-edge, FTIR and Raman spectroscopies revealed the titanium ions in the zeolite structure have predominantly tetrahedral coordination. However, it appears that the higher chitosan content in the synthesis gel imparted some hydrophilic character to the TS-1 system. Furthermore, the technique adopted for the preparation of the synthesis gel – e.g partially dried or fully dried – appears to affect the amount of framework titanium in the zeolite structure. The calcined form of the chitosan templated TS-1 zeolites exhibited higher cyclohexene conversion compared to the TS-1 material synthesised without this template, but these catalysts showed lower selectivity for cyclohexene epoxide.
- Published
- 2017
4. Inter-connected and open pore hierarchical TS-1 with controlled framework titanium for catalytic cyclohexene epoxidation
- Author
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Graham J. Hutchings, Gemma Louise Brett, Qian He, Yilai Jiao, Peter J. Miedziak, Michal Perdjon, Nicholas Dummer, Jinmin Liu, and Abdul-Lateef Adedigba
- Subjects
Aqueous solution ,Materials science ,Cyclohexene ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Hydroxide ,0210 nano-technology ,Zeolite ,Mesoporous material ,Dissolution ,Titanium - Abstract
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.
- Published
- 2018
5. Controlled and rapid growth of MTT zeolite crystals with low-aspect-ratio in a microwave reactor
- Author
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Adnan M. Al-Amer, Idris A. Bakare, Teruoki Tago, Hiroki Konno, Takao Masuda, Oki Muraza, Abdul-lateef Adedigba, and Zain H. Yamani
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Materials science ,General Chemical Engineering ,Nucleation ,Mineralogy ,General Chemistry ,Industrial and Manufacturing Engineering ,Catalysis ,Crystal ,Crystallinity ,Chemical engineering ,Environmental Chemistry ,Hydrothermal synthesis ,Zeolite ,Porosity ,Microwave - Abstract
The nucleation and growth of MTT zeolite, an important 10-membered ring (10 MR) zeolite, was controlled by a microwave-assisted hydrothermal synthesis. The effect of irradiation time (12,18, and 24 h), seed-assisted synthesis with 1 wt.% seeds for 6 h and desilication under microwave irradiation on crystallinity and porosity were investigated. Under microwave-assisted synthesis, uniform crystal size, with lower crystal aspect-ratio and suppressed phase-impurity has been obtained. The tendency of column-like crystal to form bundle of columns was reduced significantly. Seeded growth further reduced synthesis time to 6 h. Post-synthetic treatment was used to obtain larger pore volume of MTT zeolites. Some of the protonated MTT samples were tested in n-hexane cracking as model reaction. Characterization techniques such as XRD, FE-SEM, N2 adsorption–desorption, 27Al MAS NMR and NH3-TPD have been carried out to obtain insight in the physico-chemical properties of zeolite catalysts.
- Published
- 2013
6. EFFECT OF MULTI-WALLED CARBON NANOTUBES ON THE MECHANICAL AND THERMAL PROPERTIES OF NATURAL RUBBER.
- Author
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Abdul-Lateef, Adedigba A., Al-Harthi, Mamdouh, and Ali Atieh, Muataz
- Subjects
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CARBON nanotubes , *THERMAL analysis , *NANOCOMPOSITE materials , *NANOSTRUCTURED materials , *GLASS transition temperature , *THERMOPHYSICAL properties - Abstract
Multi-walled carbon nanotubes (MWCNTs) were used to prepare natural rubber nanocomposites (CNT-NR). Different amounts of CNT were reinforced into natural rubber using a solution casting method. By this niethod, carbon nanotubes were incorporated in NR solution and the solvent subsequently evaporated to obtain the composite. The effect of percentage composition of CNT on properties of natural rubber such as tensile strength, Young's modulus, energy absorption, glass transition, and melting temperature were studied. Characterization techniques used in this study include tensile testing machine and differential scanning calorimeter (DSC). Structural and morphological features of the CNT used in this study were obtained by conducting FE-SEM and TEM characterization. [ABSTRACT FROM AUTHOR]
- Published
- 2010
7. Controlling the Cross-Sensitivity of Carbon Nanotube-Based Gas Sensors to Water Using Zeolites
- Author
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Gopinathan Sankar, Neal T. Skipper, Abdul-Lateef Adedigba, Ivan P. Parkin, David J. Buckley, and Gwyn P. Evans
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Materials science ,Humidity ,Nanotechnology ,02 engineering and technology ,Carbon nanotube ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Molecular sieve ,01 natural sciences ,0104 chemical sciences ,Nanomaterials ,law.invention ,Adsorption ,law ,Selective adsorption ,General Materials Science ,Thin film ,0210 nano-technology ,Water vapor - Abstract
Carbon nanotube-based gas sensors can be used to detect harmful environmental pollutants such as NO2 at room temperature. Although they show promise as low-powered, sensitive, and affordable monitoring devices, cross-sensitivity of functionalized carbon nanotubes to water vapor often obscures the detection of target molecules. This is a barrier to adoption for monitoring of airborne pollutants because of the varying humidity levels found in real world environments. Zeolites, also known as molecular sieves because of their selective adsorption properties, are used in this work to control the cross-sensitivity of single-walled carbon nanotube (SWCNT)-based sensors to water vapor. Zeolites incorporated into the sensing layer are found to reduce interference effects that would otherwise obscure the identification of NO2 gas, permitting repeatable detection over a range of relative humidities. This significant improvement is found to depend on the arrangement of the SWCNT-zeolite layers in the sensing device, ...
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