含磷铝单元的AlMCM-41负载的磷化钨催化剂DBT HDS性能

摘要

通过微波加热的方法,分别合成了硅/铝比(30、40、50、55、60)不同的含磷铝结构单元的AlMCM-41复合分子筛,并以此为载体采用共浸渍和程序升温高纯氢气还原的方法制备了负载量为30％(以WO3计)的磷化钨催化剂.采用X射线衍射(Xm)、BET比表面积测定、扫描电镜(SEM)及X光电子能谱(XPS)等手段对催化剂进行了表征.通过高压微反装置对催化剂的二苯并噻吩( DBT)加氢脱硫(HDS)性能进行了评价.结果表明,在催化剂表面检测到活性组分WP和以类似-Al-O-W-P结构形式存在的具有一定活性的物种.WP是主要的活性相,硅/铝比对WP活性相在催化剂表面所占的比例有一定影响.不同硅/铝比的催化剂表现出不同的选择性加氢性能,但直接加氢脱硫是催化剂DBT HDS的主要路径.其中,硅铝比为55的催化剂具有相对最高的DBT HDS的转化率(93.1％),且其直接加氢脱硫产物(联苯)的选择性相对最高(82.7％),这对减少氢耗,保护环境有利.%As a support, AIMCM-41 containing aluminophosphate building units with different Si/AI molar ratio( Si/Al= 30, 40,rn50, 55, 60, respectively) was synthesized by microwave heating method. The supported tungsten phosphide( WP) catalysts withdifferent Si/AI molar ratio were prepared by impregnation and H2 -IPR ( temperature programed reduction in hydrogen flow) method.The samples were characterized by X-ray diffraction ( XRD) , BET specific surface area, scanning electron microscopy ( SEM) andX-ray photoelectron spectroscopy ( XPS) methods. The dibenzothiophene ( DBT) hydrodesulfurization ( HDS) activities of thecatalysts were evaluated by a fixed-bed micro-reactor. Active species of WP and the structure of -AI-O-W-P, the matter with someactivity, were detected on the catalysts surface. WP was the dominative active phase. The peKentage of active phase WP on thecatalyst surface was influenced by the Si/AI molar ratio. Catalysts with different Si/AI molar ratio exhibited different selectivehydrogenation performances, and direct hydrodesulfurization( DDS) was the main DTB HDS route. Catalyst with Si/AI molar ratioof 55 was found to give a higher DDS products ( PB) selectivity of 82. 7% and a higher DBT HDS conversion of 93. 1% , whichwas favor to reducing the hydrogen consumption and protecting the environment.