无定形TiO2的F、La共掺杂及其光催化脱硫性能

F and La co-doping of amorphous TiO2 and its photocatalytic performance in the desulfurization

摘要:

同时加入氟化铵溶液和硝酸镧溶液对钛酸四丁酯进行水解，制备了F、La共掺杂的无定形TiO2即F-La-TiO2（Am），并应用于DBT（二苯并噻吩）为探针的模拟柴油的光催化氧化脱硫。XRD、FT-IR、XPS、UV-vis、SEM、PL及VB-XPS表征结果表明F和La成功共掺杂后，F的电负性使催化剂的禁带宽度变窄，La-O键的生成提供了更多的氧空位，促进了杂质能级的生成，有效抑制了电子-空穴的复合。在优化的操作条件下，即催化剂用量为1 wt%（以模拟柴油为基准），O/S摩尔比为15:1，剂油比（v/v）为1:1，脱硫率达到了94.10%，与无定形的La-TiO2（Am）、F-TiO2（Am）和锐钛矿型F-La-TiO2（An）相比分别提高了12.71%、9.52%和27.5%。催化剂重复使用四次，脱硫率仍可达到85%以上，机理研究表明主要活性中间物种是超氧自由基（·O2-）和空穴（ h+）。

Abstract:

At the same time, ammonium fluoride solution and lanthanum nitrate solution were added to hydrolyze tetrabutyl titanate, and F-La-co-doped amorphous TiO2, namely F-La-TiO2 (Am), was prepared, and applied to the photocatalytic oxidative desulfurization of simulated diesel fuel with DBT (dibenzothiophene) as the probe. The characterization results of XRD, FT-IR, XPS, UV-vis, SEM, PL and VB-XPS showed that after successful co-doping of F and La, the electronegativity of F narrowed the band gap of the catalyst, and the formation of La-O bonds provided more oxygen vacancies, promoted the formation of impurity energy levels, and effectively inhibited the recombination of electrons. Under the optimized operating conditions, that is, the catalyst dosage is 1 wt% (based on simulated diesel), the O/S molar ratio is 15:1, the agent-oil ratio (v/v) is 1:1, and the desulfurization rate reaches 94.10%, which is 12.71%, 9.52% and 27.5% higher than the amorphous La-TiO2(Am), F-TiO2(Am) and anatase F-La-TiO2(An), respectively. The catalyst was reused four times, and the desulfurization rate could still reach more than 85%, and the mechanism studies showed that the main active intermediate species were superoxide radicals (· O2-) and holes (h+).