煤直接液化催化剂预硫化过程中氢的作用研究

Research of hydrogen action during pre-sulfidation of direct coal liquefaction catalyst

在不同温度、不同氢气分压下预硫化制备了系列硫铁催化剂,并在5 MPa 1%H_(2)S-H_(2)气氛、360℃下研究了其催化萘加氢活性。借助XRD、MES、SEM-EDS、ICP和GC-MS等表征手段,研究了不同温度下氢气在预硫化过程中的作用。结果表明,预硫化过程中氢气的引入有利于硫的传递,从而促进了硫化。在不同温度下均有利于活性相Fe_(1−x)S生成,但不同预硫化温度下氢气的作用有所不同。50℃预硫化时,氢气的引入可以有利于硫的传递,使得催化活性有所上升,但该温度下依然存在大量单质Fe和单质S;150℃预硫化时催化活性最好,单质Fe含量下降没有单质S生成,随着氢气分压的增大,萘加氢转化率由60.6%增加至69.1%;300℃预硫化时氢气将催化剂表面的硫还原至低价态,不利于硫的传递,在催化剂颗粒内部观察到晶态的Fe_(3)O_(4),进而催化活性有不同程度的下降。

A series of iron sulfide catalysts were prepared by pre-sulfidation at different temperatures and different hydrogen partial pressures,and their catalytic naphthalene hydrogenation activities were studied under 5 MPa 1%H_(2)S-H_(2) atmosphere at 360℃.By means of XRD,MES,SEM-EDS,ICP and GC-MS,the effect of hydrogen on the pre-sulfidation process at different temperatures was studied.The results show that the introduction of hydrogen during the pre-sulfidation process facilitates the transfer of sulfur,thereby promoting the sulfidation.The effect of hydrogen is different at different pre-sulfidation temperatures.When pre-sulfidation at 50℃,the introduction of hydrogen can be beneficial to the transfer of sulfur,which increases the catalytic activity,but a lot of elemental Fe and elemental S can still be observed at this temperature;when pre-sulfidation at 150℃,the catalytic activity is the best.The content of zero-valent Fe decreases and no pure S is observed.With the increase of hydrogen partial pressure,the hydrogenation conversion of naphthalene increases from 60.6%to 69.1%.When pre-sulfidation at 300℃,the catalytic activity decreases with the introduction of hydrogen.Hydrogen reduces the sulfur on the catalyst surface to low valence state and crystalline Fe_(3)O_(4) is observed inside the catalyst particles,which is not conducive to the transfer of sulfur.