Highly-Dispersed NiO Nanoparticles on SBA-15 for Oxidative Dehydrogenation of Propane to Propylene
- 化学化工－已发表论文 
[中文文摘]采用浸渍法通过改变焙烧气氛制备了系列NiO/SBA-15(wNiO=20%)催化剂,并考察了催化剂的丙烷氧化脱氢(ODHP)反应性能.实验结果表明,与在静止和流动空气中焙烧的催化剂相比,在1%NO/He(VNO/VHe=1:99)气氛中焙烧的NiO/SBA-15-NO具有优异的低温丙烷氧化脱氢制丙烯性能,在350°C时,丙烷的转化率和丙烯收率分别约达29%和13%.反应温度升至450°C时,丙烯的选择性仍保持在45%左右.X射线粉末衍射(XRD)和透射电镜(TEM)测试结果表明,1%NO/He气氛可有效抑制焙烧过程中NiO纳米颗粒的团聚,使NiO物种高分散于SBA-15的孔道中.H2-程序升温还原(H2-TPR)和O2-程序升温脱附(O2-TPD)测试结果表明,随着NiO在SBA-15上分散度的提高,催化剂的抗还原性增强,ODHP活性氧物种O-的含量增加,进而使1%NO/He气氛中焙烧的NiO/SBA-15-NO在较宽的温度范围内(350-450°C)均具有良好的丙烯选择性,并显著提高了催化剂的低温活性. [英文文摘]A series of NiO/SBA-15 (wNiO=20%) catalysts were prepared by impregnating SBA-15 with an aqueous solution of nickel nitrate followed by calcining under three different atmospheres. The resulting materials were studied with regard to the oxidative dehydrogenation of propane (ODHP) to propylene.Compared to the catalysts calcined under either static or moving air, the NiO/SBA-15-NO catalyst calcined under flowing 1%NO/He (VNO/VHe=1:99) atmosphere demonstrated greater activity for this reaction at low temperature. Propylene yield of ~13% with propane conversion of ~29% was obtained at 350 °C and the propylene selectivity remained at about 45% even when the reaction temperature was raised to 450 °C.X-ray diffraction (XRD), transmission electron microscopy (TEM), H2-temperature program reduction (H2-TPR), and O2-temperature program desorption (O2-TPD) characterizations were used to investigate the intrinsic differences between these NiO/SBA-15 catalysts. It was found that NiO species in the catalyst calcined under 1%NO/He atmosphere were highly dispersed inside the mesopores of SBA-15. With the increasing of NiO dispersion on the support, the quantity of NiO species with a reduction temperature above 450 °C increased significantly. In addition, the density of O- species on the catalyst calcined under 1%NO/He was much higher than that in the case of the other two samples. These factors are responsible for the superior performance of the NiO/SBA-15-NO catalyst for the ODHP reaction over the temperature range 350 to 450 °C.