大尺寸多级孔g-C3N4/MHPTS催化剂的制备及其性能研究

研发高效、易回收的催化剂具有很高的实际应用价值.采用多模板法制备了一种新型的大尺寸多级孔钛硅酸盐(MHPTS),并以其为载体,采用简单的浸渍-热聚合法制备了g-C₃N₄/MHPTS复合催化剂.MHPTS具有连续贯通的大孔结构,传质速度快;几十纳米的超薄壁厚意味着大孔孔壁上的介孔孔道非常短,缩短了反应物和产物分子进出孔道的时间;微孔提供了大量的活性位点.在热反应条件下,MHPTS对环己烯的催化环氧化转化效率远高于常规的TS-1分子筛.此外,由于g-C₃N₄的负载使g-C₃N₄/MHPTS对光的吸收范围延伸至可见光,提高了催化剂的光吸收能力.结果表明,在光热协同作用下,g-C₃N₄/MHPTS对环己烯的催化环氧化转化效率进一步提高.

Preparation and properties of macro-sized hierarchical porous g-C3N4/MHPTS catalyst

Developing highly efficient and easily recyclable catalysts is massively desirable for applications. A novel macro-sized hierarchical porous titanasilicate (MHPTS) is prepared using multi-template method. g-C₃N₄/MHPTS is prepared through simple impregnation-thermal polymerization with MHPTS as the carrier. MHPTS has 3D continuous pass-through macropore channels, which ensures fast mass transfer; the ultra-thin wall thickness of tens of nanometers suggests that the mesoporous channels on the macropore wall are significantly short in length, which saves the diffusion time of reactant and product molecules in the pore channel. The micropores provide abundant active sites. Under thermal reaction conditions, the catalytic conversion efficiency of MHPTS to cyclohexene epoxidation reaction is higher than that of conventional TS-1 molecular sieve. The loading of g-C₃N₄ extends the absorption range of the catalyst to visible range and facilitates the light absorption capacity of g-C₃N₄/MHPTS. The results indicate that the conversion of cyclohexene has reached a higher level under the photo-thermal synergy.