表面修饰多壁碳纳米管负载二氧化钛的制备及催化碳酸二甲酯与苯酚酯交换反应的性能(英文)

Preparation and catalytic property of modified multi-walled carbon nanotube-supported TiO_2 for the transesterification of dimethyl carbonate with phenol

制备了表面修饰多壁碳纳米管负载TiO2的催化剂,并将其应用于碳酸二甲酯与苯酚的酯交换反应.采用X射线电子能谱、透射电子显微镜、低温N2吸附-脱附和X射线衍射等对催化剂进行了表征.结果表明,以低浓度的氨水(0.4%)代替去离子水作为沉淀剂时,制备的催化剂显示出更好的催化活性、分离性与重复使用性.考察了TiO2负载量、催化剂用量及反应时间对反应性能的影响.在最佳反应条件下,苯酚转化率为42.5%,碳酸甲苯酯与碳酸二苯酯的总选择性达到99.9%以上.经过4次重复使用后,催化剂的活性略有下降.

Modified multi-walled carbon nanotube-supported TiO2 samples were prepared and used as an efficient heterogeneous catalyst for the transesterification of dimethyl carbonate with phenol. The catalysts were characterized by X-ray photoelectron spectroscopy, transmission electron micros copy, N2 adsorption-desorption, and X-ray powder diffraction. The results showed that the catalyst, which was prepared using a low concentration （0.4%） of ammonium hydroxide as the precipitant instead of ionized water, had better catalytic activity, separability, and reusability properties. The effects of the Ti02 loading, amount of catalyst and reaction time on the performance of the trans- esterification reaction were also studied. Under the optimum reaction conditions, the conversion of phenol reached 42.5% with over 99.9% selectivity for methyl phenyl carbonate and diphenyl car bonate. The catalyst could be reused for the transesterification in four runs with only slight loss of its catalytic activity.