预煅烧对橄榄石生物质气化催化性能的影响

预煅烧对橄榄石生物质气化催化性能的影响

  • 摘要: 利用小型固定床反应器研究预煅烧对橄榄石生物质气化催化性能的影响。研究发现,经过预煅烧处理的橄榄石具有比原矿更高的催化活性。通过XRD、SEM/EDX和H2-TPR等表征发现,预煅烧使橄榄石的晶体结构发生改变,Fe从橄榄石的镁铁硅酸盐结构中脱出,以α-Fe2O3的形式存在于颗粒表面,而且使其分布比原矿均匀。随着预煅烧温度增高和时间的延长,橄榄石颗粒表面可还原的Fe2O3数量增加,其催化活性相应提高,说明α-Fe2O3的形成是预煅烧使橄榄石催化活性提高的原因。经过800℃~1100℃预煅烧会造成橄榄石抗磨损性能下降。综合催化活性和抗磨损能力等因素,900℃下煅烧4h是比较合理的橄榄石预煅烧处理方法。

     

    Abstract: Effects of precalcination on catalytic activity of olivine in biomass gasification were investigated in a fixedbed reactor. The experimental results show that the catalytic activity of the olivine is improved by precalcination at higher temperature. The results of X-ray Diffraction (XRD), Local Scanning Electron Microscopy/Energy Dispersive X-ray Analysis (SEM/EDX), and Temperature Programmed Reduction (H2-TPR) indicate that the crystalline structure of the olivine is modified by the precalcination. The α-Fe2O3 formed on the surface of the precalcined olivine sample is due to the eduction of iron from the olivine structure (iron and magnesium orthosilicate) during precalcination. The distribution of Fe elements on the surface of the precalcined olivine particle becomes more uniform than that of the natural sample. The amount of reducible iron oxide on the surface of samples increases with the increase of precalcination temperature and time. It can be inferred that the increase of olivine catalytic activity after precalcination is attributed to the formation of α-Fe2O3. However, the antiattrition ability of the olivine particles decreases after precalcination at 800℃~1100℃. The optimal catalytic activity and anti-attrition ability can be obtained at the precalcination temperature of 900℃ for 4h.

     

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