原子隔离的VSbOx纳米簇催化丙烷氧化脱氢制丙稀反应的构效关系研究

Vanadia-based catalysts have been paid much attention in the selective oxidative dehydrogenation of propane to produce propene. It has been found that the key-point for the development of highly effective vanadia-based catalysts is to obtain highly isolated vanadia active sites. However, huge barriers are still needed to be overcomed for the development of high effective vanadia-based catalysts due to the difficulties in the preparation of highly isolated VOx active sites, which structure needs to be stable under reaction conditions. Additionally, the V-O-support bonds of the VOx species on single component vanadia-based catalysts are hardly detectable and characterizable by spectrometric methods like Raman and thus the characterization of such catalysts as well as the studies on structure-performance relationship are inaccessible.. Atom-isolated vanadia active sites can be achieved in virtue of the -Sb-O-V-O-Sb- frameworks of antimony-vanadium mixed oxide. Such atom-isolated vanadia active sites are stably anchored in the -Sb-O-V-O-Sb- frameworks and thus can keep stable under reaction conditions. Moreover, all bonds related to such atom-isolated vanadia active sites in -Sb-O-V-O-Sb- frameworks can be detected and characterized by means of spectrometric techniques like Raman and then the studies on the structure-performance relationship for antimony-vanadium mixed oxide catalysts are accessible.. In this program, the catalysts based on nano-size antimony-vanadium mixed oxide clusters will be synthesized and characterized. Their structure-performance relationship in the oxidative dehydrogenation of propane to propene will also be systematically studied. According to the results arising in this program, new ideas and kernel knowledge for the preparation of catalysts with highly isolated active sites, the development of high effective catalysts for the oxidative dehydrogenation of propane to propene and the exploitation of new selective xidation reactions of saturate light hydrocarbons based on antimony-vanadium mixed oxide can be achieved.

在丙烷选择氧化脱氢制丙烯的研究中，钒基催化剂受到高度重视，制备出高度隔离的钒物种被认为是开发出高效钒基催化剂的关键。对单一组分的钒基催化剂而言，在载体表面生成高度隔离钒物种需要将表面钒浓度限制在很低的水平，而且这样制得的高度隔离钒物种在反应条件下稳定性不足，并且其所含的V─O─support键很难表征，导致对钒物种所关联的键位与催化性能关联的确切信息无法获得。锑钒复合氧化物稳定的-Sb-O-V-O-Sb-骨架可以得到高稳定性的、可被光谱表征方法直接表征的、原子隔离的钒物种。本项目开展锑钒复合氧化物纳米簇催化剂的制备和结构表征，并研究其在丙烷氧化脱氢制丙烯反应中的构效关系,希望为制备具有高度隔离活性位的催化剂提供可供借鉴的新思路；为开发丙烷选择氧化脱氢制丙烯的新型高效催化剂提供借鉴；为开发基于VSbOx复合氧化物的饱和低碳烃新选择氧化过程提供核心知识。

在丙烷选择氧化脱氢制丙烯的研究中，钒基催化剂受到高度重视，制备出高度隔离的钒物种被认为是开发出高效钒基催化剂的关键。锑钒复合氧化物稳定的-Sb-O-V-O-Sb-骨架可以得到高稳定性的、可被光谱表征方法直接表征的、原子隔离的钒物种。本项目系统地研究了构建VSbOx纳米簇催化剂所相关的具有特殊孔道结构和粒子形貌的多孔-高比表面氧化硅材料、氧化硅－氧化钛复合材料的合成化学；细致地研究了不同制备方法制备的负载型VSbOx纳米簇催化剂的结构－催化性能之间的构效关系。通过本项目的研究工作，我们比较深入地掌握了在纳米孔道中构建VSbOx 纳米簇结构的制备化学知识，获得了VSbOx复合氧化物中-Sb-O-V-O-Sb-骨架所包含的原子隔离的钒物种的活性位结构信息，发现在分子氧为氧化剂的丙烷氧化脱氢制丙稀反应中，这种Sb-O-V-O-Sb-骨架所包含的原子隔离的V物种可以表现出高活性和高选择性兼顾的特性，得到了和V-Mg-O催化剂相近的丙烯收率；同时发现锑钒复合氧化物VSbOx 纳米簇结构及其催化性能受到载体孔道特性、采用的锑钒前体的不同化学性质、不同的制备方法的影响。. 同时，本项目通过直链烷烃改性合成制备方法还获得了多种具有特殊孔道结构和粒子形貌的多孔-高比表面氧化硅材料、单纯晶相氧化钛纳米粒子、介孔SiO2-TiO2复合材料、新型有序介孔碳材料，这为开发新型负载型选择氧化/氧化脱氢催化剂提供了极具应用潜力的载体材料和硬模板材料，这些实验结果也拓展应用于相关的研究领域并表现出对原有催化体系显著的增强效果。. 本项目所获得的VSbOx 纳米簇催化剂的制备、结果表征、丙烷氧化脱氢催化性能的研究结果是进一步开发基于VSbOx 复合氧化物的饱和低碳烃高效选择氧化过程不可或缺的核心知识，也为开发基于单组分、多组分过渡金属氧化物的饱和低碳烃高效活化、高效选择氧化的新型催化剂提供了一个具有高度可行性的新思路。