High-Resolution Solid-State NMR Study of the Occurrence and Thermal Transformations of Silicon-Containing Species in Biomass Materials

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• 作者：Jair C. C. Freitas ; Francisco G. Emmerich ; and Tito J. Bonagamba
• 刊名：Chemistry of Materials
• 出版年：2000
• 出版时间：March 2000
• 年：2000
• 卷：12
• 期：3
• 页码：711 - 718
• 全文大小：204K
• 年卷期：v.12,no.3(March 2000)
• ISSN：1520-5002

文摘

The occurrence of silicon in two kinds of biomass (rice hulls and endocarp of babassucoconut) and the thermal transformations taking place in these materials under heattreatments are studied here. We report also the production, characterization, and study ofcarbonaceous materials with high SiC content through the carbothermal reduction of silica,using these natural precursors. X-ray diffraction, scanning electron microscopy, and ¹³C and²⁹Si room temperature high-resolution solid-state NMR measurements are used in thecharacterization and study of the materials as well as the process of SiC formation. Importantconclusions about the nature of silicon in these types of biomass and the effects of heattreatments on the structure of silicon-containing species are derived from the resultspresented. It is shown that silicon in these materials occurs in two distinct forms: amorphoushydrated silica and organically bound silicon species. The influence of spin-lattice relaxationdynamics on the NMR spectra is discussed, evidencing the role played by the paramagneticdefects produced in the materials through pyrolysis.