Ni-Mo-W非负载型催化剂加氢脱硫性能的改进及结构探究

STUDY OF UNSUPPORTED Ni-Mo-W CATALYST STRUCTURE AND HDS PERFORMANCE IMPROVEMENT

在共沉淀法制备三元(Ni-Mo-W)非负载型催化剂过程中加入聚乙二醇(PEG),采用XRD、BET及微反活性评价考察PEG的最佳相对分子质量及加入量,采用Py-IR,SEM,TEM等后续表征分析最佳条件下PEG对催化剂性质和脱硫活性的影响,采用XRD、LRS对Ni-Mo-W复合氧化物的结构进行深入探究。结果表明:在PEG的相对分子质量为600、加入量为Mo物质的量的20%时,催化剂对劣质柴油的脱硫率最高,可达99.8%;此条件下的Ni-Mo-W非负载型催化剂形态规整,活性组分分布均匀,相互间排列有序,孔隙最为发达,酸位得到充分暴露。合成的Ni-Mo-W复合氧化物是具有不同Mo、W配位的新型Ni基化合物,Ni-W构成主体及表层,内部填充部分主要由Ni-Mo构成。

The advantages of unsupported catalyst in the HDS are obvious and attract much attention. In this paper,PEG was added in the process of preparing trimetalic unsupported catalyst by corecipitation,and the resulting unsupported catalyst was then characterized by XRD,BET,and evaluated in a micro-reactor system to test the optimal amount and the molecular weight of PEG added. Py-IR,SEM, TEM techniques were used to investigate the effect of PEG under optimal conditions on the properties and the HDS activity of the catalyst. The structures of the unsupported Ni-Mo-W catalysts in oxidation state were analyzed by XRD and LRS. The results show that the trimetalic unsupported catalyst pre- pared by adding PEG with molecular weight of 600 as Mo moles of 20 ~ has the best HDS activity,the HDS rate reaches to 99.8~/00. Under the best catalyst preparation conditions,the Ni-Mo-W composite has a regular morphology, better distribution of active component, ordered arrangement, optimal pore struc- ture, and fully exposed acid sites. The Ni-Mo-W composite in oxidative state is a new type of Ni-based compound with different Mo and W coordination modes, the bulk and the surface layer of the catalyst are composed of Ni-W,while part of the internal contains Ni-Mo structure.