Mo/Al-CLM催化剂表面上钼的分散性及其加氢脱硫性能

THE DISPERSITY OF MOLYBDENUM ON THE SURFACE OF Mo/Al-CLM AND ITS HYDRODESULFURIZATION ACTIVITY

采用浸渍法和干混法制备了负载钼的层柱分子筛催化剂 ,利用 XRD分析了样品表面上钼的分散性。结果表明 ,通过浸渍或干混热处理 ,钼含量低的催化剂中 ,钼在层柱分子筛表面上自发分散而使晶相钼物种消失 ;而钼含量高时 ,催化剂表面上保留晶相钼物种。通过氨水处理 ,可以使低、中或高钼含量的催化剂上所有的晶相钼物种消失 ,并溶解掉一部分单层分散和全部多层分散的表面钼物种。通过噻吩加氢脱硫微反活性测定 ,发现中等钼含量的催化剂活性最佳 ,而且催化剂上不溶于氨水并呈单层分散的表面钼物种是加氢脱硫活性中心。用氨水处理能溶解掉部分非活性的表面钼物种及晶相钼物种 ,使得活性钼物种充分裸露 ,从而提高催化剂的活性。

The dispersity of MoO 3 or APM on the surface of Mo/Al CLM was determined by X ray diffraction(XRD) The results showed that the XRD peaks of MoO 3 or APM crystalline disappeard if the Mo loading was low in the Mo/Al CLM catalysts which were prepared either by impregration or mixed heating method The XRD peaks of Mo species were observed when the Mo loadings were high The Mo/Al CLM catalysts of medium leveled Mo content showed the highest activity of hydrodesulfurization The monolayer dispersed Mo which isnt extracted by ammonia is the HDS active site Ammonia can extract Mo crystalline and a portion of non active dispersed Mo Then the active Mo species on the surface of Mo/Al CLM can be exposed to the reactants and the activity of Mo/Al CLM was thus improved