CO2在纳米SiO2/TiO2悬浮体系中的光催化还原

用水热法合成了氧化硅改性的具有高比表面积、高催化活性的锐钛型二氧化钛, 并在其悬浮体系中将CO₂光催化还原合成甲醇. 采用XRD, TEM, 物理吸附, UV-Vis吸收光谱和FTIR等表征手段对催化剂结构特征进行了研究. 结果表明: 添加氧化硅后, 氧化硅和二氧化钛之间形成Si—O—Ti键, 抑制了TiO₂晶粒生长, 提高了锐钛型TiO₂的比表面积, 且随着含硅量的增加, SiO₂/TiO₂的UV吸收逐步蓝移, 禁带宽度增加. 还原反应结果表明: SiO₂/TiO₂具有光催化还原活性, 且随着含硅量的增加先增加后减小, 当SiO₂质量分数为3.5%时, SiO₂/TiO₂复合催化剂反应活性最强, 5 h内甲醇产量可达到21.0 mg/L, 并有少量甲醛生成.

Photocatalytic Reduction of CO2 in the Suspension System of Nano-SiO2/TiO2

Silica-modified anatase titanium dioxide was prepared by the hydrothermal method, with large surface area and high photocatalytic activity. Photocatalytic reduction of CO₂ was carried out to synthesize methanol in the aqueous suspension system of nano TiO₂. The catalyst was characterized by XRD, TEM, BET, UV-Vis diffuse reflectance and FTIR spectroscopy methods. The results showed formation of Si—O—Ti bond on the silica-modified titanium dioxide surfaces. The addition of silica to TiO₂ could restrain the growth of TiO₂ crystalline grain and enhance the surface area. The silica-modified titanium dioxides had significant blue shift in UV absorption compared to the bulk TiO₂. The reductive results of CO₂ showed that the nano SiO₂/TiO₂ already obtained obvious photocatalytic reduction activity. When the addition of silica to TiO₂ reached w(silica)＝3.5%, it gave the highest activity, producing 21.0 mg/L of methanol during 5 h reaction under the irradiation of 365 nm UV light.