机械活化硫铁矿催化剂的表征及催化性能评价

Characterization and evaluation of catalytic performance of mechanically activated pyrite catalysts

煤直接液化工业催化剂面临原料成本高、水耗高和产生含盐废水等问题,有必要使用机械活化后的天然矿物作为煤直接液化催化剂,但需解决矿物催化剂粒径较大、过滤干燥后易板结及影响分散性和催化性能等问题。以某硫铁矿物为原料,以具有良好供氢性能的四氢萘为研磨介质,通过控制机械活化时间,得到一系列平均粒径小于5μm的矿物催化剂,催化剂无需过滤干燥,可直接加入煤直接液化反应体系中使用。利用扫描电镜、粒径分析、X射线衍射光谱和X射线光电能谱等手段对催化剂进行表征,矿物原料经机械活化后未发生明显聚集,活化2 h后催化剂平均粒径快速减小至2.82μm,延长活化时间后粒径减小速度放缓。机械活化过程对矿物中活性相FeS 2晶型无明显影响,但活化后催化剂表面Fe 2+和S 2-2量均明显增加,有利于催化活性的提高。催化剂在四氢萘中的沉降速度受粒径影响小,小粒径催化剂分散性基本相同。在相同的反应条件下,平均粒径为2.46μm的硫铁矿催化剂具有最佳的煤直接液化反应性能,转化率和油产率分别达到83.30%和43.53%。

Industrial catalysts for direct coal liquefaction are faced with high raw material cost,high water consumption and salt-bearing wastewater.It is necessary to use natural minerals after mechanical activation as catalysts for direct coal liquefaction,but the problems such as large particle size of mineral catalysts,easy hardening after filtration and drying,and affecting dispersion and catalytic performance should be solved.By controlling the mechanical activation time,a series of natural mineral catalysts with average particle size less than 5μm were obtained by using a pyrite as raw material and tetralin with good hydrogen supply performance as grinding medium.The catalysts can be directly added to the direct coal liquefaction reaction system without filtration and drying.The catalysts were characterized by means of scanning electron microscopy,particle size analysis,X-ray diffraction spectroscopy and X-ray photoelectricity spectroscopy.The average particle size of the catalysts decreased rapidly to 2.82μm after activation for 2 hours,and the decreased rate of particle sizes slowed down with the increase of activation time.The mechanical activation process had no obvious effect on the crystalline form of the active phase FeS 2,but the amount of Fe 2+and S 2-2 on the surface of the catalyst increased significantly after activation,which is conductive to the improvement of catalytic activity.The sedimentation rate of catalyst in tetralin was little affected by particle size,and the dispersion of catalysts with small particle size were basically the same.Under the same reaction conditions,the pyrite catalyst with an average particle size of 2.46μm had the best performance of direct coal liquefaction,and the conversion and oil yield reached 83.30%and 43.53%,respectively.