Abstract The catalytic conversion of biomass-derived tars over char during long tests (over 6 h) is studied. The syngas is generated in a steam-blown fluidized-bed gasifier employing wood pellets and conducted to a second tubular reactor where non-activated char particles are fluidized. The gasifier operated at 750 °C whereas the temperature of the secondary reactor was varied between 750 °C and 875 °C. The evolution of the tar conversion, gas composition and internal structure of the used catalysts were studied. At 750 °C, the initial catalytic activity of the char was low and deactivation occurs rapidly. However, as the reactor temperature increased, the catalytic activity of the char improved significantly. At 875 °C, the initial conversion of tar was above 70% and over 64% after 5 h of operation. Moreover, the conversion of the heaviest tars was above 80% during the entire test. At this temperature, the decrease in tar conversion is attributed to the consumption of the char by steam gasification since its catalytic activity increased during of the test. In these conditions the char bed with an initial weight of 32 g converted approximately 12 g of tars (benzene not included) after 5 h of operation.

中文翻译：

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下游焦床中生物质合成气的焦油转化

摘要 研究了长时间试验（超过 6 小时）期间生物质衍生焦油在炭上的催化转化。合成气在蒸汽喷射流化床气化炉中产生，采用木颗粒，并被输送到第二个管式反应器，在那里非活性碳颗粒被流化。气化炉在 750 °C 下运行，而二级反应器的温度在 750 °C 和 875 °C 之间变化。研究了焦油转化率、气体组成和所用催化剂的内部结构的演变。在 750 °C 时，炭的初始催化活性很低，失活很快。然而，随着反应器温度的升高，炭的催化活性显着提高。在 875 °C 下，焦油的初始转化率在 70% 以上，运行 5 小时后超过 64%。而且，在整个测试过程中，最重的焦油的转化率在 80% 以上。在此温度下，焦油转化率的降低归因于蒸汽气化过程中焦炭的消耗，因为其催化活性在测试期间增加。在这些条件下，初始重量为 32 克的炭床在运行 5 小时后转化了大约 12 克焦油（不包括苯）。