摘要
首先成功合成了介孔氧化锆母体,采用SAXRD、氮气吸脱附、HRTEM等表征发现,制备的介孔氧化锆其晶胞常数a0为12.14nm,介孔直径为3.7nm,介孔的孔壁厚度大约为8.34nm,比表面积和孔体积分别为163.5m2/g和0.15cm3/g;将这种介孔材料进行硫酸化制得固体超强酸,并考察了焙烧温度对其结构的影响,结果发现:随着焙烧温度的提高,催化剂的介孔结构在600℃前基本稳定,但是更高温度会导致介孔结构的破坏;较低温度焙烧得到的硫酸化氧化锆介孔孔壁上是无定形的,温度升高逐步转变成为四方晶相和单斜晶相;NH3-TPD表征发现400℃焙烧后催化剂具有较为宽泛的氨气脱附峰,酸量较少;500℃焙烧后的催化剂的酸性强、具有最大酸量;600℃焙烧后的催化剂酸强度降低,同时酸量下降;700℃焙烧的催化剂酸强度较弱,酸量也进一步减少;800℃焙烧后催化剂基本上没有表现出酸性。催化剂应用于甲苯甲醛缩合反应中,发现500℃焙烧的催化剂显示出最高的活性,甲醛转化率达到45.7%,更高温度焙烧后转化率明显下降,800℃焙烧催化剂没有表现出任何活性。
As the activity of different acids for the condensation between toluene and formaldehyde depended on the proporation of its strong acid site, mesoporous zirconia supported sulfate acid was synthesized via the self-assembly method and characterized via XRD, N2-adsorption and HRTEM. The thermal stability of the prepared mesoporous zirconia supported sulfate acids were checked at different calcination temperature. It was found that the structure of mesoporous zirconia remained under 600℃, but damaged at higher temperature. NH3-TPD found that the catalyst calcined at 500℃ has the highest acid amount and this catalyst showed the highest activity in the condensation between tolu ene and formaldehyde. The conversion of formaldehyde reached 45.7%.
出处
《材料工程》
EI
CAS
CSCD
北大核心
2008年第10期223-227,共5页
Journal of Materials Engineering
基金
国家自然科学基金项目(20433030,906100002)
关键词
介孔氧化锆
高热稳定性
固体酸材料
sulfated mesostructure zirconia
solid superacid
condensation reaction
