CAJ | 학술논문

用传统的等体积浸渍法或蒸发法制备了Ni/La_2O_3/γ-Al_2O_3与Ni/La_2O_3/α-Al_2O_3催化剂,在没有稀释气体的条件下进行了甲烷干重整反应.采用H_2程序升温还原、N_2吸附脱附、X射线衍射、透射电子显微镜、热重-差示扫描热量以及程序升温加氢等手段对新鲜的与反应后的催化剂以及沉积的碳进行了表征.结果表明,催化剂上有四种含碳物种,以三种形态存在,即无定形碳(聚合态)、丝状碳或石墨碳.这些催化剂上积炭的数量与种类各不相同,依赖于催化剂中金属Ni颗粒的大小与载体的织构特性.丝状碳的形成及其形貌与金属Ni颗粒的大小有着密切的联系.Ni颗粒小于15nm时能抑制丝状碳的形成与沉积.减少积炭的数量,同时能产生较多的活性C_a物种,从而在一定程度上导致催化剂具有较好的活性与稳定性.
용전통적등체적침지법혹증발법제비료Ni/La_2O_3/γ-Al_2O_3여Ni/La_2O_3/α-Al_2O_3최화제,재몰유희석기체적조건하진행료갑완간중정반응.채용H_2정서승온환원、N_2흡부탈부、X사선연사、투사전자현미경、열중-차시소묘열량이급정서승온가경등수단대신선적여반응후적최화제이급침적적탄진행료표정.결과표명,최화제상유사충함탄물충,이삼충형태존재,즉무정형탄(취합태)、사상탄혹석묵탄.저사최화제상적탄적수량여충류각불상동,의뢰우최화제중금속Ni과립적대소여재체적직구특성.사상탄적형성급기형모여금속Ni과립적대소유착밀절적련계.Ni과립소우15nm시능억제사상탄적형성여침적.감소적탄적수량,동시능산생교다적활성C_a물충,종이재일정정도상도치최화제구유교호적활성여은정성.
Ni/La_2O_3/γ-Al_2O_3 and Ni/La_2O_3/α-Al_2O_3 catalysts were prepared by the incipient wetness impregnation and evaporation methods. Their catalytic properties for the dry reforming of methane without a diluting gas were studied. The fresh and used catalysts and deposited carbon were characterized by H_2 temperature-programmed reduction, N_2 adsorption-desorption, X-ray diffraction, transmission electron microscopy, thermogravimetry coupled to differential scanning calorimetry, and temperature-programmed hydrogenation. The results showed that there were four carbon species that existed as three types, namely, amorphous (polymeric), filamentous, and graphitic carbon. The amount and type of carbon species on the catalysts depended on the size of Ni particles and texture of the support. The formation and morphology of filamentous carbon were clearly related to the size of Ni particles. Ni particles less than 15 nm suppressed the formation and deposition of filamentous carbons, decreased the amount of carbon deposition, and had more active C_α species, resulting in a better activity and higher stability of the catalysts.