刘碧玉,袁霞.单过渡金属配位磷钨酸铵盐的合成及其催化环己酮氨肟化[J].分子催化编辑部,2014,(2):140-147
单过渡金属配位磷钨酸铵盐的合成及其催化环己酮氨肟化
Preparation of Transition Metal Substituted Mono-lacunary Phosphotungstic-ammonium Salt and its Catalytic Performance in Ammoximation of Cyclohexanone
投稿时间:2013-11-07  修订日期:2013-12-17
DOI:
中文关键词:  过渡金属  磷钨酸  环己酮  氨肟化
英文关键词:transition metal  lacunary polyoxotungstates  cyclohexanone  ammoximation
基金项目:改性Y型分子筛封装有机-无机复合杂多酸盐及其催化烯烃环氧化性能研究
作者单位E-mail
刘碧玉 湘潭大学 lby_xuexi_2012@126.com 
袁霞 湘潭大学 13327321357@189.cn 
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中文摘要:
      摘要:以磷钨酸和过渡金属盐在pH值为4.0~5.0的条件下合成了4种具有Keggin结构的单过渡金属配位磷钨酸铵盐NH4MPW11(M= Zr2 ,Co2 ,Ni2 ,Cu2 ),通过红外、紫外、热重、X射线衍射、循环伏安法等技术对这类杂多化合物的结构和性质进行了表征,并考察了它们在环己酮氨肟化反应中的催化性能。结果表明:单过渡金属配位的磷钨酸铵盐NH4MPW11( M= Zr2 ,Co2 ,Ni2 ,Cu2 )具有典型的Keggin结构,过渡金属离子配位后,热稳定性和氧化性增强;在催化环己酮氨肟化反应中,NH4MPW11的催化性能低于单缺位磷钨酸铵盐(NH4PW11),其中NH4ZrPW11为催化剂,性能优于M=Co2 ,Ni2 ,Cu2 的催化剂,环己酮的转化率达到85.1%,环己酮肟的选择性达到92.1%,而NH4CuPW11的催化性能则下降显著;H2O2的分解实验表明,过渡金属配位的磷钨酸铵盐对H2O2分解均存在一定的促进作用,分解能力随过渡金属种类而变化,其中NH4CuPW11对H2O2的分解率高达72.3%,这是造成过渡金属配位的磷钨酸铵盐在环己酮氨肟化反应中催化性能下降的主要原因;回收催化剂的红外表征表明,氨肟化反应后的NH4MPW11结构不会发生改变。
英文摘要:
      Abstract:Four kinds of different transition metal substituted mono-lacunary Keggin-structure phosphotungstic-ammonium salt NH4MPW11(M= Zr2 ,Co2 ,Ni2 ,Cu2 ) were successfully synthesized with phosphotungstic acid and transition metal salts at pH 4.0~5.0. The obtained compounds were characterized by IR, UV, TG, X-ray diffraction, cyclic voltammetry and their catalytic performance in ammoximation of cyclohexanone were investigated. The characterization results reveal that NH4MPW11(M= Zr2 ,Co2 ,Ni2 ,Cu2 ) have the typical Keggin-structure, whose thermostability and oxidability are improved after substituted by transition metal ion; NH4MPW11 show lower activity compared with mono-lacunary phosphotungstic- ammonium salt (NH4PW11) in ammoximation of cyclohexanone, of which NH4ZrPW11 exhibits better catalytic performance than the other three ones, the conversion of cyclohexanone reaches 85.1% and the selectivity of cyclohexanone oxime is up to 92.1% in the presence of NH4ZrPW11, while the catalytic performance of NH4CuPW11 decreases significantly. The decomposition tests of H2O2 with NH4MPW11 under the similar condition of cyclohexanone ammoximation shows that different kind of transition metals promoted the invalid decomposition of H2O2 in different degree, the decomposition ratio of H2O2 is even up to 72.3% with NH4CuPW11, which is the main reason resulted in the decline of catalytic performance of NH4CuPW11 in ammoximation of cyclohexanone. FT-IR spectra of recovering catalyst shows that their structure still keep integrated after ammoximation of cyclohexanone reaction.
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