生物油提质中失活催化剂焦炭前驱物分析

ANALYSIS OF COKE PRECURSOR ON DEACTIVATED CATALYST ON BIO-OIL UPGRADING PROCESS

采用XRD、热重、红外、核磁等表征手段,对生物油在CO气氛下提质中所使用的Co/Mo/Ni催化剂上的焦炭前驱物进行分析表征。结果表明:催化剂外表面上的焦炭前驱物主要是低沸点的饱和烃类化合物;催化剂内部的结焦前驱物主要为芳香族碳氢化合物。焦炭可能以无定形状态存在于催化剂外表面和催化剂的孔道内。另外,分子较小的芳烃化合物进入催化剂内部并逐渐芳构化形成大分子芳烃,进一步缩合形成焦炭,最终堵塞催化剂通道和覆盖催化剂活性中心,这是导致催化剂失活的主要原因。

Characterizations of coke precursor on Co/Mo/Ni bifunctional catalyst on bio-oil upgrading process in the CO atmosphere are analyzed with thermogravimetry, X-ray diffraction, infrared analysis, scanning electron microscopy and nuclear magnetic resonance. The results showed that the deposition of coke precursor on catalyst surface is mainly lowboiling point of saturated hydrocarbon compounds and the coke precursor of internal channels of deactivated catalyst is major aromatic hydrocarbon compounds. The coke precursor is in an amorphous state, which was highly dispersed on the catalyst surface or into the catalyst micropore. In addition, the catalyst deactivation mechanism is speculated that the small molecule aromatic compounds entered the internal channels of catalyst and formed macromolecular aromatic hydrocarbons by aromatization gradually, further condensed to form coke and obstructed the channels and cover the active center of the catalyst.