K改性Mo-SBA-16催化剂催化乙烷选择氧化制乙烯和醛类

采用超声辅助等体积浸渍法制备了K改性Mo掺杂SBA-16催化剂x K/Mo-SBA-16,评价其对乙烷选择氧化反应的催化性能,并利用XRD、TEM、N_2吸附-脱附、UV-Vis、UV-Raman和FT-IR等对催化剂物化性质进行表征,同时考察反应温度和K含量等因素对催化剂性能的影响。结果表明,K的添加提高了产物中醛类选择性。在V(C_2H_6)∶V(O_2)=3∶1和反应温度550℃条件下,0. 1K/5. 0Mo-SBA-16催化剂上乙醛选择性为17. 1%,总醛(包括乙醛和丙烯醛)产率7. 4%。碱金属K的添加改变了催化剂中活性组分的结构和分散度,孤立和高分散的MoO_4四面体逐渐转变为低聚扭曲的MoO_x四面体,可能形成了K_2Mo_2O_7新相。

Selective oxidation of ethane to ethylene and aldehydes over K-modified Mo- SBA-16 catalysts

The K-modified and Mo-doped SBA-16 catalysts,denoted as xK-Mo-SBA-16,were prepared by ultrasound-assisted incipient wetness impregnation method.Catalytic performance of those catalysts for selective oxidation of ethane were evaluated.The physicochemical properties of all the prepared samples were characterized by means of XRD,TEM,N₂ adsorption-desorption,UV-Vis,UV-Raman and FT-IR.Influences of reaction temperature and K loading on catalytic performance were investigated.The experiment results demonstrated that selectivity of aldehydes in products were improved due to the addition of K element.Acetaldehyde selectivity was 17.1% and overall aldehydes (including acetaldehyde and acrolein) yield achieved 7.4% at 550 ℃ over 0.1K/5.0Mo-SBA-16 catalyst when V(C₂H₆)∶V(O₂)=3∶1.Structure and dispersion of active component were changed because of K addition.Isolated MoO₄ species were transformed to oligomeric twisted MoO_x tetrahedra and K₂Mo₂O₇ phase was formed.