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| Glycerol oxidation catalyzed by modified straw ash supported Pt |
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| DOI：10.19902/j.cnki.zgyz.1003-7969.240279 |
| KeyWord:glycerol straw ash glyceric acid modification |
| FundProject:国家自然科学基金面上项目（21875125）；内蒙古自治区大学生创新创业训练计划项目（S202210138009）；赤峰学院青年科研基金项目（CFXYQNZR2225） |
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| Abstract: |
| In order to achieve high value utilization of biomass, Pt-based catalysts of Pt/ash-b, Pt/ash-a, Pt/ash-ba and Pt/ash-CeO2 were prepared by pre-treating straw ash using alkali modification, acid modification, combined acid and alkali modification, and introduction of CeO2, respectively. The composition, structure, loading amount of Pt, size of Pt particle, surface acidity and alkalinity, and Pt reduction activity of the catalysts were determined by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectroscopy (ICP-OES), transmission electron microscopy (TEM), CO2 programmed temperature-raising desorption (CO2-TPD) and NH3 programmed temperature-raising desorption (NH3-TPD), and hydrogen-programmed temperature-raising reduction (H2-TPR), respectively. In addition, the catalytic performance of the catalysts for the oxidation of glycerol was investigated. The results showed that acid and alkali modification increased the content of SiO2 in Pt/ash-a and Na2O in Pt/ash-b to 73.61% and 12.51%, respectively, compared with the unmodified catalyst (Pt/ash). The content of Na2O in Pt/ash-CeO2 (18.92%) was higher than the introduction of CeO2 (2.96%). The actual loading amount of Pt (about 0.05%) and the average diameter of Pt particle size (1.5-2.3 nm) were closer in each catalyst. CO2-TPD and NH3-TPD results demonstrated that the number of base sites on the surface of the Pt/ash-b and Pt/ash-CeO2 catalysts obtained by alkali treatment and introduction of CeO2 significantly increased. H2-TPR results showed that the loading of CeO2 in the Pt/ash-CeO2 catalysts enhanced the reduction capacity of the Pt species. The Pt/ash-b and Pt/ash-CeO2 in the glycerol conversion (30.8% and 29.7%) were higher under alkaline conditions, which proved that the increase in the number of base sites was beneficial to improve the conversion of glycerol by the catalysts. Under non-alkaline conditions, the Pt/ash-CeO2 catalyst exhibited the highest glycerol conversion (252%), with a glyceric acid selectivity of 32.4% and a glycerol aldehyde selectivity of 27.5%, suggesting that the increase in the Pt reduction capacity in Pt/ash-CeO2 facilitated the oxidation of the primary hydroxyl group of glycerol to produce glycerol aldehyde, which was further oxidized to produce glycerol acid. Pt/ash-CeO2 had good stability after 5 cycles under non-alkaline conditions. In summary, the introduction of CeO2 effectively regulates the acid/base sites of the straw ash supported Pt catalysts and improved the activity of Pt and selectivity for glycerol aldehyde and glyceric acid. |
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