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| Preparation of phosphotungstic acid supported on hollow mesoporous silica and its application in biodiesel synthesis |
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| DOI： |
| KeyWord:solid-acid catalyst hollow mesoporous nanomaterials biodiesel esterification |
| FundProject:国际交流与合作项目 (BX 2019018) |
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| Abstract: |
| Using ethyl orthosilicate as raw material, solid silica spheres (SiO2) were synthesized by the improved Stber method. Then Na2CO3 and C16TAB were used for selective one-step etching to obtain hollow mesoporous silica nanospheres (HMSN). Finally, the modified impregnation method was applied to introduce phosphotungstic acid as the active centre, thus the nano-catalyst of phosphotungstic acid supported on hollow mesoporous silica (HPW/HMSN) was obtained. The prepared catalyst were characterized with FTIR, XPS, XRD, BET, SEM, TEM, EDS, TGA, etc, and the acidity of the catalyst was determined. The results showed that phosphotungstic acid was successfully introduced into the surface of the carrier, and the synthesized catalyst had hollow mesoporous structure, uniform particle size and good monodispersity, the specific surface area of the catalyst was up to 481 m2/g, and the acid content (H+) was up to 340.4 μmol/g. The optimal reaction conditions of synthesizing biodiesel from oleic acid and methanol with the catalyst were obtained by single factor experiment as follows: reaction temperature 80 ℃, reaction time 2 h, molar ratio of methanol to oil 10∶ 1 and catalyst dosage 3% of total mass of materials. Under these conditions, the conversion rate of oleic acid could reach 98.7%. In addition, the catalyst had good reusability, and it maintained 85.2% conversion rate when reused for five times. |
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