摘要
以硅酸钠、三氯化钛为原料,在Si/Ti物质的量的比为2～60的范围内合成出了Ti-MCM-41分子筛。采用XRD,FTIR,UV-Raman,TEM,低温N_2吸附等对合成的Ti-MCM-41进行了表征;并以环己烯的氧化为探针反应,对其催化氧化性能进行了考察。结果表明:合成的Ti-MCM-41介孔分子筛在nSi/nTi=4时,仍然保持了MCM-41的介孔结构,而当Si/Ti物质的量的比为2时,介孔结构消失;在制备过程中对pH值的适时调节,使硅酸钠和三氯化钛得到充分的水解和混合,制备出了高钛Ti-MCM-41分子筛,同时又避免了混合凝胶在水热反应过程中pH值升高的问题。实验发现,随着分子筛中钛含量的增加,环己烯在H_2O_2体系中的氧化转化率增大,最高约为83%,氧化环己烷的收率先增大后减小,最大约为37%;1,2-环己二醇的收率逐渐增大,最大约为57%。
Ti-containing Ti-MCM-41 molecular sieves were prepared by using Na2SiO3 as silicon source and TIC13 as titanium source. The nSi/nTi, in synthesis gel varied from 2 to 60. The molecular sieves were characterized by XRD, FTIR, UV-Raman, and low temperature N2 adsorption-desorption isotherms. And the catalytic oxidation of cyclohexene was taken as the probe reaction for the catalyst activity evaluation. The results show that the Ti-MCM-41 synthesized with nSi/nTi, of 4 still keeps the mesoporous structure as MCM-41, but the mesoporous structure disappears when nSi/nTi reaches 2. It is found that Na2SiO3and TiCl3are hydrolyzed and mixed completely in the solution and high Ti-containing Ti-MCM-41 molecular sieves are synthesized due to the pH value adjusted timely in the synthesis process, which avoids from the increase of pH value in the hydrothermal reaction of the mixed gel. As the content of Ti is increased in the molecular sieves, the cyclohexene conversion using H2O2 as oxidant increases and can reach the maximum conversion of 83%. The yield of cyclohexene oxide increases first and then decreases with the increase in Ti content,maximum yield being about 37%, while the yield of 1,2-cyclohexanediol increases, maximum yield being about 57%
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2008年第5期748-754,共7页
Chinese Journal of Inorganic Chemistry
基金
物理化学国家重点学位培育建设点开放基金资助项目
