掺杂离子种类对三维有序大孔La_(0.9)Ni_(0.7)M_(0.3)O_(3+δ)催化性能的影响

Synthesis and Characterization of 3DOM La_(0.9)Ni_(0.7)M_(0.3)O_(3+δ)Perovskite Oxide Catalysts

以单分散聚甲基丙烯酸甲酯微球为模板剂,用溶胶-凝胶法分别制备了三维有序大孔3DOM La_(0.9)Ni_(0.7)M_(0.3)O_(3+δ)(M=Cu、Co和Fe)钙钛矿氧化物,并用XRD、TEM、SEM、XPS和H2-TPR等对3DOM La_(0.9)Ni_(x)Co_(1-x)O_(3+δ)的晶体结构、形貌、元素价态和比表面积等性能进行了表征。研究结果表明:3DOM La_(0.9)Ni_(0.7)M_(0.3)O_(3+δ)均能形成钙钛矿结构,金属离子M掺杂引起M/NiO_(6)八面体的变形和Ni的混合价态改变,导致晶体结构发生畸变;钙钛矿结构中氧空位的形成与B位金属离子的掺杂种类有关,Co离子的掺杂促进了B位金属还原性能,同时影响金属中心的形成;有序的三维孔结构有效降低了传质阻力,提高脱氧反应活性和选择性;苯酚的加氢脱氧反应以直接脱氧反应为主,同时发生部分异构化和加氢反应。在常压、350℃条件下3DOM La_(0.9)Ni_(0.7)Co_(0.3)O_(3+δ)催化剂的单程转化率为29.79%,苯的选择性为91.00%。

Using monodispersed polymethylmethacrylate microspheres as templates,three-dimensional ordered macroporous 3DOM La_(0.9)Ni_(0.7)M_(0.3)O_(3+δ)(M=Cu,Co,and Fe)were synthesized via the sol-gel method to create perovskite oxide.Characterization using XRD,TEM,SEM,XPS,and H_(2)-TPR revealed the crystal structure,morphology,element valence state,and specific surface area of 3DOM La_(0.9)Ni_(0.7)M_(0.3)O_(3+δ).The results indicated the formation of a perovskite structure.The introduction of metal ions M led to octahedron deformation and altered valence states of Ni,causing crystal structure distortion.The creation of oxygen vacancies in the titanite structure was influenced by the type of metal ions doping at the B site.Co ion doping enhanced metal reduction performance at the B site and impacted metal center formation,resulting in a highly dispersed metal Ni center and increased oxygen vacancies.The ordered three-dimensional pore structure reduced mass transfer resistance,enhancing deoxygenation reaction activity and selectivity.Phenol hydrodeoxygenation predominantly underwent direct deoxygenation,with simultaneous isomerization and hydrogenation reactions.At normal pressure and 350°C,the La_(0.9)Ni_(0.7)Co_(0.3)O_(3+δ)catalyst exhibited a single-pass conversion rate of 29.79%and a benzene selectivity of 91.00%.