A series of unsupported mono- and bimetallic Mo_nW_12-nS₂ catalysts were synthesized by alumina elimination from supported Mo_nW_12-nS₂/Al₂O₃ samples using acid etching. Alumina supported catalysts have been in turn prepared by using monometallic H₄SiMo₁₂O₄₀ and H₄SiW₁₂O₄₀ heteropolyacids (HPAs), their mixture with Mo/W atomic ratio equal to 1/11 and 3/9, and mixed bimetallic H₄SiMo₁W₁₁O₄₀ and H₄SiMo₃W₉O₄₀ HPAs. All catalysts were characterized by N₂ adsorption, temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), time-of-flight secondary ion mass spectrometry (ToF-SIMS), extended X-ray absorption fine structure (EXAFS) spectroscopy and powder X-ray diffraction (XRD) and their performance were evaluated in simultaneous hydrodesulfurization (HDS) of dibenzothiophene (DBT) and hydrogenation (HYD) of naphthalene. The etching process led to a successful removal of all the support and of the partially sulfided species, with sulfidation degrees of both Mo and W above 90 % on the final bulk solids. The active phase also underwent a rearrangement, as higher average length and stacking were measured on the bulk catalysts than on the original supported ones. Mixed MoWS₂ phase was evidenced in all solids, prepared from mixed HPAs (Mo_nW_12-nS₂) or from the mixture of monometallic HPAs (RefMo_nW_12-nS₂), by EXAFS and ToF-SIMS, with however a larger quantity on the MoW solids. It seems that the mixed MoWS₂ phase observed on the supported MoW catalysts is maintained through the etching process, while on RefMo_nW_12-nS₂ the mixed phase, observed in a much lesser extent in the corresponding supported catalyst, could result from the aggregation of the monometallic slabs. Mo_nW_12-nS₂ catalysts were found more effective than the monometallic catalysts and than the corresponding RefMo_nW_12-nS₂, in both dibenzothiophene hydrodesulfurization and naphthalene hydrogenation, which was related to the presence of the mixed phase maintained through the etching of the support.

通过使用酸蚀刻从负载的Mo _n W _12-n S ₂ /Al ₂ O ₃样品中消除氧化铝，合成了一系列未负载的单金属和双金属Mo _n W _12-n S ₂催化剂。通过使用单金属 H ₄ SiMo ₁₂ O ₄₀和 H ₄ SiW ₁₂ O ₄₀杂多酸 (HPA)，它们的 Mo/W 原子比等于 1/11 和 3/9 的混合物，以及混合双金属H ₄ SiMo ₁ W ₁₁ O ₄₀和H ₄ SiMo ₃ W ₉ O ₄₀ HPA。所有催化剂均以 N ₂为特征吸附、程序升温还原 (TPR)、X 射线光电子能谱 (XPS)、高分辨率透射电子显微镜 (HRTEM)、飞行时间二次离子质谱 (ToF-SIMS)、扩展 X 射线吸收精细结构 (EXAFS) 光谱和粉末 X 射线衍射 (XRD) 及其在二苯并噻吩 (DBT) 的同时加氢脱硫 (HDS) 和萘的加氢 (HYD) 中的性能进行了评估。蚀刻过程成功去除了所有载体和部分硫化物，最终块状固体上 Mo 和 W 的硫化度均高于 90%。活性相也经历了重排，因为在本体催化剂上测得的平均长度和堆积比原始负载催化剂更高。混合MoWS ₂通过 EXAFS 和 ToF-SIMS，由混合 HPA (Mo _n W _12-n S ₂ ) 或单金属 HPA (RefMo _n W _12-n S ₂ )的混合物制备的所有固体中都存在相MoW 固体的数量。似乎在负载型 MoW 催化剂上观察到的混合 MoWS ₂相通过蚀刻过程得以保持，而在 RefMo _n W _12-n S ₂上，在相应负载型催化剂中观察到的混合相的程度要小得多，这可能是由于单金属板的聚集。沫_Ñ w ^ _12-n的小号₂发现在二苯并噻吩加氢脱硫和萘加氢中，催化剂比单金属催化剂和相应的 RefMo _n W _12-n S ₂更有效，这与通过载体蚀刻保持混合相的存在有关。