Development of Phototalytic Process for Selective Oxidation of Alkansor

碱离子的加入提高了V_2O_5/SiO_2的催化活性，并改变了有效波长；由λ >400 nm光照射激发。研究了表面物质与Rb离子在异丁烷光氧化反应中的反应活性，以阐明烷烃光氧化的机理。生成丙酮和c_4化合物。最引人注目的是在Rb^+改性催化剂上生成叔丁醇。用^<18>O_2示踪研究表明，加入叔丁醇的氧原子来自气态氧，而丙酮中含有^<16>O，来自催化剂中的晶格氧。对活性物质进行了量子化学计算，发现碱离子掺杂和未掺杂样品中激发的正空穴的位置不同，这对应于激发能的差异。采用连续流反应器对氧化系统进行了试验。转化率为1.2%，对丙酮的选择性为70%。8小时内未见催化剂失活。

The addition of alkali ions to V_2O_5/SiO_2 enhances catalytic activity as well as changes the effective wavelengh ; excited by irradiation with the light lambda>400 nm. The reactivity of the surface species interacting with Rb ions in the photo-oxidation of isobutane has been investigated to clarify the mechanism of photooxidation of alkanes. Acetone and C_4-compounds were formed. The most striking point is the formation of tert-butyl alcohol over the Rb^+-modified catalyst. A tracer study with ^<18>O_2 showed that oxygen atoms incorporated into tert-butyl alcohol were from gaseous oxygen, whereas acetone contained ^<16>O which originated from the lattice oxygen in the catalyst. The quantum chemical calculations of the active species were carried out and we found that the position of the excited positive hole is different between alkali-ion-doped and undoped samples, which corresponds to the difference of excitation energy. The continuous flow reactor was tested for the oxidation system. The conversion was 1.2% and the selectivity to acetone was found to be 70%. The catalyst deactivation could not be seen for 8-hours duration.