Importance of V4+and optimal acid environment in the hydroxylation of inert benzene via activation of Csp2-H bond

Hydroxylation of inert benzene through the activation of the Csp2-H bond is a representative reaction about the transformation of C-H bonds to C-O bonds,which has far-reaching guiding significance but remains a challenging scientific problem.To overcome this problem,a series of VOx-Ga2O3/SiO2-Al2O3 were prepared to achieve an efficient and economical hydroxylation path of benzene to phenol.The results showed that the phenol yield was 72.89％(selectivity＞98.1％)under the optimum conditions.The reason is that the C-H bond in the benzene ring is activated by heterolysis over a VOx-Ga2O3/SiO2-Al2O3 catalyst.Meanwhile,the introduction of aluminum(Al)and gallium(Ga)made a qualitative change in the catalyst,enhancing the electron motion and spin motion of vanadium species,resulting in the in-crease of V4+/V5+ratio.In addition,the catalyst can provide an optimal acidic environment and a three-dimensional cross-linked surface structure that facilitates product diffusion.     

阳极氧化时间对2A12铝合金剥落腐蚀性能的影响

利用扫描电镜(SEM)、能谱仪(EDS)以及膜厚测量等分析测试方法研究了不同阳极氧化时间对2A12铝合金抗剥落腐蚀性能的影响。结果表明：随着阳极氧化时间延长,氧化膜厚度逐渐增加,其抗剥落腐蚀性能越好。当阳极氧化时间从30 min延长至60 min时,氧化膜厚度从2.43 μm增大到4.72 μm,膜厚标准差从0.75减少至0.52。但是当阳极氧化时间超过60 min后,氧化膜厚度增长趋势缓慢,膜厚标准差逐渐趋于一水平值。宏观、微观形貌综合分析结果表明,当阳极氧化时间为60 min时,2A12铝合金的耐腐蚀性能最好。