Research Of TiO₂ Modified With Amorphous Alloy Photocatalysts For Photocatalytic Synthesis Of Ammonia

Ammonia as an important inorganic chemical products plays an important role in the national economy production. People have been studying on the artificial nitrogen fixation method for a long time. Heterogeneous photocatalysis technology provides a new perspective for nitrogen fixation. Among all of the semiconductor photocatalysts, TiO2 has been considered as the most promising material in the 21 st century because of its nontoxicity, chemical inertness, high photocatalytic activity, light corrosion resistance, green and low price, etc. In this article, we doped TiO2 with amorphous alloy catalyst and investigated the effect on the photocatalysis of ammonia synthesis.Firstly, P25 was used as the main catalyst. We systematically investigated the photocatalytic activity of amorphous alloy catalyst/TiO2 under different conditions, such as the amount of catalyst, the composition of amorphous alloy catalyst, the crystalline state and the methanol concentration. The catalysts were characterized by XRD, TEM, DRS and PL, etc.. Therefore, the function of the doping components on TiO2 could be analyzed in theory. The results indicated that the optimal amount of P25 catalyst was 0.05 g/L; the optimal composition of three kinds of amorphous alloys were Ni-Cu-B (6:1,2%), Ni-Mo-B (6:1,3%) and Ni-W-B (3:1,3%); amorphous alloy catalyst was higher in photocatalytic activity than the crystalline state; the addition of methanol could greatly improve the photocatalytic activity; and there was an optimum operating condition:Ni-Mo-B (6:1,3%)/P25 as catalyst,0.05 g/L of scattered catalyst amount and 10 v% of methanol content. The total nitrogen production rate per unit mass of P25 could reach to 9.73* 104 (μg/gP25), which increased 90.78% compared with pure P25.To overcome the disadvantages of the powder catalyst, the porous anti-reflective glass was used as the catalyst support, which was prepared by reverse micelle etching method. TiO2 film was coated on the porous glass by sol-gel method, then modified with amorphous alloy catalyst. The results indicated that when using porous glass as a catalyst carrier, compared with ordinary glass as carrier, the total nitrogen production rate per unit mass of TiO2 catalyst increased 39.10%. After using for three times, the recovery rate of the porous glass used as a support was less than 1%, which was 4.99 times than that of powder catalyst. The immobilization of photocatalyst made great increase of cataryst recovery rates.