超临界水热极速合成异质结构H4SiW12O40/Bi2WO6光催化剂及其脱氮性能

采用超临界水热合成方式极速合成一种H_4SiW_(12)O_(40)/Bi_2WO_6光催化剂,通过X射线衍射(XRD)、场发射扫描电子显微镜(SEM)、透射电子显微镜(TEM)、比表面积及孔隙度(BET)测定对所合成催化剂的结构和性质进行了考察,并以吡啶含量为15 mg/g的模拟油对光催化剂的脱氮效果进行评价。结果表明,该光催化剂为二维纳米片自组装成的三维球状结构,其中,H_4SiW_(12)O_(40)与Bi_2WO_6不是简单的固载关系而是在超临界水热条件下生成一种新的晶相,正是由于这种晶相的存在,使得H_4SiW_(12)O_(40)牢固固载在Bi_2WO_6光催化剂本体上的同时,对光生载流子进行了有效疏导,提升了H_4SiW_(12)O_(40)/Bi_2WO_6光催化剂的使用寿命和光催化活性。本研究针对光催化剂制备周期与晶形发育的矛盾,将超临界水热技术与光催化剂模板导向合成技术有机结合,在获得良好晶形异质结构H_4SiW_(12)O_(40)/Bi_2WO_6光催化剂的同时明显缩短了光催化剂的制备周期,从而降低了催化剂的制备成本,攻克了光催化剂工业化应用的主要矛盾,所制备的H_4SiW_(12)O_(40)/Bi_2WO_6光催化剂轻质油脱氮效率达97%以上。

Preparation of H4SiW12O40/Bi2WO6 nano-photocatalyst by supercritical hydrothermal synthesis and its photocatalysis denitrification performance

An immobilized nano-photocatalyst H₄SiW₁₂O₄₀/Bi₂WO₆ was quickly prepared by the supercritical hydrothermal synthesis method. The properties, morphology and structure of the prepared catalysts were investigated and characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM),and transmission electron microscope (TEM) and BET, respectively. The photocatalytic denitrification properties were evaluated by using the model oil with 15 mg/g pyridine. The results show that the photocatalyst is the self-assembly three-dimensional spherical structure by two-dimensional nano-flakes, and the relationship between Bi₂WO₆ and H₄SiW₁₂O₄₀ is not a simple solid loading, but is a new crystal under the condition of supercritical water. It is because the existence of this kind of crystal that the H₄SiW₁₂O₄₀ is firmly fixed on the Bi₂WO₆ photocatalyst and the photocatalytic activity and service life of H₄SiW₁₂O₄₀/Bi₂WO₆ photocatalyst are improved. In view of the contradiction between the preparation period of photocatalyst and the crystal development, the supercritical hydrothermal technology and the photocatalyst template-oriented synthesis technology are organically combined to obtain the H₄SiW₁₂O₄₀/Bi₂WO₆ photocatalyst with good crystal heterostructure and greatly shorten the preparation period of the photocatalyst, greatly reduce the preparation cost of the catalyst and overcome the main contradiction of the industrialized application of the photocatalyst. The nitrogen removal efficiency of the prepared H₄SiW₁₂O₄₀/Bi₂WO₆ photocatalyst for light oil is as high as 97%.