羰基化石墨片催化丙烷氧化脱氢制丙烯

Carbonyl Groups Modified Graphite Sheets Catalyze Oxidative Dehydrogenation of Propane to Propene

以资源丰富的石墨片为原材料,通过简单的气相氧化处理制得羰基化石墨片,并发现羰基化石墨片可以高选择性催化丙烷氧化脱氢制丙烯:当丙烷转化率为12.4%时,丙烯的选择性高达73.9%,且副产物乙烯的选择性为13%。羰基化石墨片优良的烯烃选择性远超利用相同气相氧化处理的碳管,并且可以媲美目前催化性能最优的六方氮化硼材料。催化剂具有良好的稳定性,在505℃的反应温度下,经过48h的氧化脱氢反应测试后,催化剂性能无明显的衰减。多种表征技术表明:气相氧化处理不会破坏石墨片的结构,且保留了石墨自身的高温抗氧化性,而经过气相氧化处理羰基官能团的比例大幅度提高,羰基作为活性位与丙烷中的氢原子发生反应,自身形成羟基而丙烷则转换为丙烯,羟基在高温下与氧原子反应生成为羰基,从而完成催化剂的重生,继续下一个循环。这种发生在催化剂表面的可控催化方式,保证了丙烷氧化脱氢过程中选择性生成丙烯,避免了深度氧化。另外,石墨材料的来源广泛,成本低,作为催化剂可以极大地推动丙烷氧化脱氢的工业化。

Using earth abundant graphite sheets as raw material, carbonyl groups modified graphite sheets were prepared via a simple gaseous-phase oxidation strategy. As-prepared carbonyl groups modified graphite sheets catalyzed oxidative dehydrogenation of propane(ODHP) to propene with high target product selectivity: the product contains 73.9% propene and 13% ethene when the propane conversion is 12.4%. Its high target product selectivity was much better than carbon nanotube that treated by gaseous-phase oxidation, and could compare favorably with the state-of-the-art hexagonal boron nitride catalysts. After 48 h stability test at 505 ℃, there was no obvious variation in the propane conversion and olefins selectivity, demonstrating the remarkable stability of the carbonyl groups modified graphite sheets catalysts. The characterization results revealed that gaseous-phase oxidation didn’t destroy the structure of graphite sheets and inherit the nature of high thermal stability against oxidation. The content of carbonyl groups increased significantly after gaseous-phase oxidation treatment. As active sites, carbonyl groups could abstract the hydrogen atoms from propane and form hydroxyl groups. Hydroxyl groups could react with oxygen atom and regenerate to carbonyl group. The high target product selectivity can be attributed to the controllable reaction style on catalyst surface. Furthermore, graphite sheets are rich in resource and low cost. As a catalyst, it would promote the industrialization of ODHP.