石墨相氮化碳负载磷钨酸杂化材料的制备及其氧化脱硫催化性能

以1-丁基-3-甲基咪唑溴离子液体([Bmim]Br)、磷钨酸(H_3PW_(12)O_(40))和g-C_3N_4为原料,采用原位沉淀法合成了负载型[Bmim]_3PW_(12)O_(40)/g-C_3N_4催化剂(BPWO/g-C_3N_4)。通过XRD、FT-IR、UV-vis、氮气吸附、TEM和XPS等手段对催化剂的形貌和结构进行了表征,并以二苯并噻吩(DBT)的正庚烷溶液为模拟油、过氧化氢为氧化剂,考察了各组分负载量、催化剂用量、氧/硫物质的量比(O/S)和反应温度变量等对其氧化脱硫效果的影响。结果表明,BPWO/g-C_3N_4具有Keggin型杂多阴离子结构特征,BPWO (20%)/g-C_3N_4催化剂具有最优的对DBT的氧化脱硫性能,在50℃、O/S物质的量比为6.0的条件下反应180 min,可以完全氧化浓度为800μg/g的含DBT模拟油。同时,该BPWO/g-C_3N_4催化剂具有良好的重复使用性能,循环使用八次后其对DBT的氧化活性没有明显降低。

Preparation of g-C3N4 supported phosphotungstate hybrid materials and their catalytic performance in the oxidative desulfurization

A series of supported[Bmim]₃PW₁₂O₄₀/g-C₃N₄ catalysts (BPWO/g-C₃N₄) was prepared by coprecipitation, with 1-butyl-3-methylimidazole bromide, phosphotungstic acid and g-C₃N₄ as the raw materials. The morphology and structure of the BPWO/g-C₃N₄ catalysts were characterized by XRD, FT-IR, UV-vis, N₂ physisorption, TEM and XPS; the effects of catalyst composition, oxygen to sulfur (O/S) ratio, catalyst amount and reaction temperature on the oxidative desulphurization efficiency were investigated by using n-heptane solution of dibenzothiophene (DBT) as a model oil and hydrogen peroxide as the oxidant. The results indicate that the BPWO/g-C₃N₄ catalysts have a Keggin-type heteropoly anionic structure and BPWO is well dispersed on g-C₃N₄. The BPWO(20%, mass ratio)/g-C₃N₄ catalyst exhibits the optimal oxidation performance towards DBT. Under 50℃ and with a O/S molar ratio of 6.0, DBT in the model oil with a concentration of 800 μg/g can be completely oxidized over the BPWO(20%, mass tatio)/g-C₃N₄ catalyst in 180 min. Moreover, the BPWO(20%, mass ratio)/g-C₃N₄ catalyst displays a good reusability and can be recycled for at least 8 cycles without any decrease in the DBT oxidation activity.