Cu、N共掺杂TiO2纳米管光催化重整甘油制备合成气

通过碱性水热-离子交换法制备了Cu、N共掺杂TiO₂纳米管(Cu/N-TNT)，对其光催化重整甘油制备合成气性能进行了研究。结果表明，Cu/N-TNT具有富含氧空位(O_V)的管状结构，N以Ti-N形式取代部分O形成杂质能级，Cu以Cu²⁺形式掺杂在催化剂晶格间隙和表面，Cu、N共掺杂促进TiO₂表面电荷有效分离，有利于其光催化重整甘油制备合成气活性和选择性的提高。紫外光照射8 h时，掺Cu量为0.15%的Cu/N-TNT催化剂上CO和H₂产量分别为7.3和8.5 mmol·g^-1，是原始TiO₂的9.1和70.8倍，n_H2/n_CO从0.52提高为1.18，n_CO/n_CO2从0.21提高至0.42。Cu/N-TNT表面N和O_V为醛类脱羰和甲酸脱水生成CO提供反应活性位点，Cu作为浅势阱提高光生电子-空穴分离效率。光生空穴(h⁺)是光催化重整甘油制备合成气过程中的主要活性物种，大量羟基自由基(·OH)和超氧自由基(·O₂^-)会导致甘油过度氧化，使CO选择性降低。

Preparation and photocatalytic properties of Cu, N co-doped TiO2 nanotubes for glycerol reforming to syngas

Cu, N co-doped TiO₂ nanotubes (Cu/N-TNT) were prepared by alkaline hydrothermal-ion exchange method, and the photocatalytic properties for glycerol reforming to syngas (H₂ and CO) were studied. The results show that Cu/N-TNT catalyst has tubular structures with abundant oxygen vacancies (O_V). N forms the impurity energy level by substituting the partial O in the form of Ti-N. Cu is doped into the crystal lattice gap and surface of the catalyst in the form of Cu²⁺. Cu, N co-doping promotes the effective surface charge separation on the TiO₂, and improves the photocatalytic activity and selectivity for glycerol reforming to syngas. CO and H₂ yields were 7.3 and 8.5 mmol· g^-1 on Cu/N-TNT catalyst doped with 0.15% Cu, which were 9.1 and 70.8 times those on the original TiO₂. The molar ratio of H 2/CO was increased from 0.52 to 1.18, and the molar ratio of CO/CO₂ was raised from 0.21 to 0.42 after 8 h of UV irradiation. N and O_V on Cu/N-TNT surface provide the active sites for the decarbonylation of aldehydes and dehydration of formic acid to produce CO. Cu acts as the shallow potential traps to inhibit the electron-hole recombination. Photogenerated holes (h⁺) play vital roles on the syngas generation during the photocatalytic reforming of glycerol, and excessive hydroxyl radical (·OH) and superoxide radical (·O₂^-) favor the deep oxidation of glycerol and decrease the selectivity of CO.