Influence of preparation conditions on the catalytic activity of high surface area silica in partial methanol oxidation
| Autor: | Sulaiman N. Basahel, Tarek Ali, Kamal M.S. Khalil, Katabathini Narasimharao, Hatem A. Mahmoud |
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| Rok vydání: | 2017 |
| Předmět: |
Formamide
Methyl formate General Chemical Engineering Inorganic chemistry 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Industrial and Manufacturing Engineering 0104 chemical sciences Catalysis Tetraethyl orthosilicate Hydrolysis chemistry.chemical_compound chemistry Environmental Chemistry Partial oxidation Methanol 0210 nano-technology Selectivity |
| Zdroj: | Chemical Engineering Journal. 330:852-862 |
| ISSN: | 1385-8947 |
| DOI: | 10.1016/j.cej.2017.08.027 |
| Popis: | High surface area SiO2 samples were synthesized by one-step hydrolysis and co-condensation at different pH (between 3.0 and 6.0) using tetraethyl orthosilicate as the Si source and formamide as the drying additive. The effects of the presence of H2O, formamide and NH3 solution on the hydrophobic nature, textural properties and catalytic functionality of SiO2 were investigated. The physico-chemical properties of the samples were measured by XRD, FTIR, SEM, TEM, N2-physisorption and NH3-TPD techniques. It was observed that the use of formamide led to the formation of strong Si-O-Si bonds and the samples possessed a high surface area (325–853 m2 g−1), large pore size (42.5 A) and large pore volume (0.875 cm3 g−1). The characterization results also indicated that SiO2 sample prepared in the absence of water at pH = 3 possessed fewer surface hydroxyl groups, leading the sample to have predominantly hydrophobic nature. An increase in water content in the SiO2 precursor solutions resulted in an increase in the average particle size with a more hydrophilic nature. All synthesized SiO2 samples were tested for partial oxidation of methanol at a temperature range of 200–400 °C. The sample synthesized at pH = 3 without water offer 90% conversion at 400 °C; however the SiO2 sample synthesized with low water content (100 mmol) at pH = 4 offered the best selectivity (83%) to methyl formate and formaldehyde with moderate methanol conversion (72%). The SiO2 sample prepared at pH = 6 with more water content offered less methanol conversion (60%) and low selectivity toward oxygenated products. It is evident that SiO2 samples that possessed better textural properties and moderate hydrophobicity performed better in partial methanol oxidation. |
| Databáze: | OpenAIRE |
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