分子筛-氧化锌复合填料的制备及其结构对光学性能的影响

Preparation of molecular sieve–zinc oxide composite pigment and relationship between its structure and optical properties

探究了分子筛(MS)的结构和氧化锌(ZnO)的负载方式对分子筛-氧化锌(MS–ZnO)复合填料光学性能的影响,以研制高紫外-可见光-近红外(UV–VIS–NIR)反射型热控填料。先采用正硅酸乙酯(TEOS)为原料制备出SBA-15和MCM-48两种不同结构的分子筛。然后采用后嫁接法或直接生长法将ZnO分别负载于它们之中,形成具有多界面反射结构的ZnO/SBA-15和ZnO/MCM-48和具有包覆结构的Zn–SBA-15和Zn–MCM-48。所得SBA-15和MCM-48分子筛整体的紫外反射率超过0.95。采用不同结构分子筛制备的Zn/SBA-15粉体和Zn/MCM-48粉体经过高温煅烧后的太阳吸收比都为0.05。ZnO负载方式受分子筛结构的影响较大,三维孔道结构的分子筛MCM-48较简单的二维孔道结构SBA-15更易与ZnO复合形成包覆结构,且经历高温化学相变生成Zn_(2)SiO_(4)后,Zn–MCM-48比ZnO/MCM-48拥有更好的光反射能力,太阳吸收比只有0.03。用不同结构的分子筛改性都可以得到光学性能比ZnO更好的MS–ZnO复合填料。采用实验周期短的直接生长法制备的MS–ZnO复合填料虽然受限于分子筛的结构,但拥有更高的UV–VIS–NIR反射能力。

The effects of molecular sieve(MS)structure and zinc oxide(ZnO)loading method on optical properties of the molecular sieve–zinc oxide(MS–ZnO)composite pigment were studied to develop a thermal control pigment with high ultraviolet-visible-near infrared(UV-VIS-NIR)reflectance.Firstly,two kinds of molecular sieves i.e.SBA-15 and MCM-48 with different structures were synthesized from tetraethyl orthosilicate(TEOS).Secondly,the MS–ZnO composite pigments with a multi-interface reflective structure i.e.Zn O/SBA-15 and Zn O/MCM-48 were prepared by post-synthesis grafting method,and those with a coating structure i.e.Zn–SBA-15 and Zn–MCM-48 were prepared by direct growth method.The overall UV reflectivity of the SBA-15 and MCM-48 molecular sieves was 0.95 above.Zn/SBA-15 and Zn/MCM-48 powders had the same solar absorbance of 0.05 after high-temperature calcination though they were prepared from the molecular sieves with different structures.The ZnO loading effectiveness is greatly affected by the structure of molecular sieve,and MCM-48 having a three-dimensional porous structure is easier to be incorporated with ZnO to form a coating structure than SBA-15 having a two-dimensional porous structure.The solar absorbance of Zn–MCM-48 was only 0.03 after a chemical phase transformation to Zn_(2)SiO_(4) at high temperature,showing better light reflectivity than ZnO/MCM-48.The MS–ZnO composite pigment prepared with whichever kind of molecular sieve has better optical properties than ZnO.Although limited to the structure of molecular sieve,the MS–ZnO composite pigment prepared by direct growth method with less experimental time has higher UV-VIS-NIR reflectivity.