渣油悬浮床加氢水溶性催化剂预硫化研究 Ⅱ 钼酸盐硫化产物的XPS分析

通过XPS分析法对钼酸盐的硫化行为进行了考察,分别考察了四价钼物种质量分数和硫钼元素的质量分数比，发现硫化产物的表面化学组成中四价钼质量分数和硫钼元素质量分数比不成正比，证实了该产物表面钼的硫化物不完全以MoS2形式存在。未经过临氢加热的硫化产物表面的四价钼物种的质量分数显著低于经过临氢加热的样品的质量分数，说明临氢加热在钼酸盐的硫化过程中起了重要作用。氯化铵是钼酸盐硫化过程中有效的助硫化剂，当它的用量增大时，硫化产物表面四价钼的质量分数也增大。以蒽为探针，使用化学探针法测定了硫化产物在渣油加氢过程中的催化活性，发现随着氯化铵用量的增加，产物的催化活性也相应提高，印证了XPS测定结果。

Study on the sulfurization of water-soluble catalysts for slurry-bed hydroprocessing of residue Ⅱ XPS analysis of sulfurized product of molybdate

The catalyst with molybdate as the precursor for the slurry-bed hydroprocessing of residue needs to be sulfurized for higher catalytic activity. In this study, ammonium molybdate is dispersed in lubricant oil and sulfurized under different conditions. XPS is employed to analyze the surface composition of the sulfurized products. Sodium sulfide is employed as sulfurization reagent and ammonium chloride is employed as auxiliary sulfurization reagent. The sulfurization conditions examined in this study included the amount of NH_4Cl added and whether the sulfurization product is heated under hydrogen or not. Chemical probe method is employed to measure the hydrogenation activity of the sulfurized catalysts. Anthracene is employed as the probe to undergo the hydrogenation with the existence of sulfurized catalysts, and the anthracene conversion is used to show the hydrogenation activity of the catalyst used. According to the XPS spectra obtained, the molar ratio of molybdenum of different valences and the molar ratio of sulfur to molybdenum is considered respectively. It is discovered that under different sulfurization conditions, the molar proportion of Mo IV and the molar ratio of sulfur to molybdenum do not form a direct ratio, thus it is concluded that the sulfides of molybdenum in the sulfurization products are not only composed by MoS_2, so that a new definition of sulfurization ratio is suggested. When the sulfurization product is not heated under hydrogen, the molar fraction of Mo IV and the sulfurization ratio is much lower than that of being heated. It is also observed that the ratio of Mo IV and the sulfurization ration increase with the increase of the amount of the NH_4Cl, which results from the special sulfurization mechanism of the molybdate. The catalytic activity measured using the method of chemical probe shows that the catalytic activity is promoted along with the molar ratio of ammonium chloride added, which is in accord with the results obtained by XPS.