摘要
采用XRD、N2吸附、11BMASNMR、NH3-TPD和催化性能评价等方法研究了B2O3/TiO2-ZrO2催化剂的结构、酸性及催化环己酮肟气相Beckmann重排反应性能间的关系。结果表明,催化剂中的B2O3同时以三配位的BO3和四配位的BO4结构单元存在;催化剂的酸性与B2O3的配位结构有关。随着B2O3含量的增加,催化剂中三配位硼(BO3结构单元)与四配位硼(BO4结构单元)的比例增大,催化剂表面的酸强度和酸浓度也相应提高。催化剂的反应活性和选择性分别与中等强度酸位的酸量及其占总酸量的百分率有较好的对应关系。
The relationship between structure, acidity and catalytic performance of titania-zirconia supported boria catalysts (B2O3/TiO2-ZrO2) for vapor-phase beckmann rearrangement of cyclohexanone oxime to epsilon-caprolactam was investigated. A series of catalysts with boria loading ranging from 8 to 20% wt. were prepared and characterized by XRD, adsorption of nitrogen, B-11 MAS NMR and NH3-TPD techniques. Both tetrahedral BO4 and trigonal BO3 species were detected as the basic units of the supported boria. The ratio of the two boron species was dependent on the boria loading. The coordination of boron appeared to significantly affect the acidities of these materials and the acidity was closely related to the relative amount of BO3. The catalytic performance of B2O3/TiO2-ZrO2 catalyst for vapor-phase beckmann rearrangement reaction was correlated closely to the acid site of medium strength.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2002年第11期1086-1092,共7页
Chinese Journal of Inorganic Chemistry
