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采用分步浸渍法制备了Ni O-WO3/γ-Al2O3系列催化剂,运用X射线衍射(XRD),激光拉曼光谱(Raman),程序升温还原(TPR),氨气程序升温脱附(NH3-TPD),紫外-可见漫反射光谱(UV-vis DRS)等方法考察了n(W)/n(Ni+W)比例对Ni O-WO3/γ-Al2O3催化剂的表面结构、氧化还原性能、酸碱性以及异丁烷氧化脱氢制异丁烯性能的影响。研究结果表明,n(W)/n(Ni)比例对Ni OWO3/γ-Al2O3系列催化剂的表面活性物种种类有较大影响,当W含量较高时,其表面主要形成WO3晶粒和Ni-Al尖晶石,而当W含量较少时,表面主要形成聚钨酸盐、Ni WO4和Ni-Al尖晶石物种;适量的W存在有利于提高Ni O-WO3/γ-Al2O3催化剂的氧化还原性能和可还原晶格氧数量,并且增加W的比例能够提高催化剂表面强酸中心的数量。n(W)/n(Ni)存在最适宜比例,当n(W)/n(Ni+W)=0.2,Ni O-WO3/γ-Al2O3催化剂具有最佳的异丁烷氧化脱氢性能,这与催化剂表面的活性物种具有较好的脱氢性能、可还原晶格氧物种的增多以及表面强酸中心数量的提高有关。
Ni O-WO3 / γ-Al2O3 series catalysts were prepared by the step impregnation method. The catalysts were characterized by X-ray diffraction (XRD), Raman Raman spectroscopy, temperature programmed reduction The effects of n (W) / n (Ni + W) ratio on the surface structure, redox properties and acidity of Ni O-WO3 / γ-Al2O3 catalysts were investigated by means of UV-visible DRS, TPD and UV- Alkaline and Isobutane Oxidative Dehydrogenation to Isobutene Performance. The results show that the ratio of n (W) / n (Ni) has a significant effect on the species of surface active species of Ni OWO3 / γ-Al2O3 catalysts. When the content of W is higher, Al spinel. However, when the content of W is small, the surface mainly forms polytwist, Ni WO4 and Ni-Al spinel. The presence of suitable amount of W is beneficial to the oxidation of Ni O-WO3 / γ-Al2O3 catalyst The reduction performance and the amount of reducible lattice oxygen, and increasing the ratio of W, can increase the number of strong acid sites on the catalyst surface. The best ratio of n (W) / n (Ni) is that NiO-WO3 / γ-Al2O3 catalyst has the best oxidative dehydrogenation performance for isobutane when n (W) / n This is related to the better dehydrogenation activity of the active species on the catalyst surface, the increase of reducible lattice oxygen species and the increase of the number of strong acid sites on the surface of the catalyst.