Propane oxidative dehydrogenation using CO 2 over CrO x /Fe–CeO 2 catalysts
Propane oxidative dehydrogenation using CO 2 over CrO x /Fe–CeO 2 catalysts
复制标题
CrO x /Fe−CeO 2 催化剂上CO 2 丙烷氧化脱氢
DOI：
10.1039/d2cy01563c
复制
发表时间：
2023
影响因子：
5
通讯作者：
Tsilomelekis, George
中科院分区：
文献类型：
--
作者：
Wang, Hedun;Nguyen, Thu D.;Tsilomelekis, George
研究了Fe掺杂CeO2负载的CrOx位点在co2辅助丙烷氧化脱氢中的动力学行为。采用Fe和Ce前驱体共沉淀法合成载体，湿浸渍法制备CrOx。XRD和拉曼分析证实，在低负载下，载体表面存在分散的CrOx位点，而在高负载下，载体表面发现了小的Cr2O3纳米颗粒。通过H2-TPR测量证实，添加CrOx位点重建了可用的表面氧位点，增强了催化剂的还原性。本研究表明，从丙烷转化率和丙烯选择性的角度来看，在低反应温度下，基于CrOx的催化剂优于母载体。在高温下，由于丙烷干重整占主导地位，CrOx位点对丙烯生产的影响减弱。建立了基于14个基本步骤的Langmuir-Hinshelwood动力学模型，以解释丙烷脱氢、逆水气转换和干重整等主要反应途径。回归的动力学数据表明，在载体上掺入CrOx使丙烷脱氢的活化能降低了60-75%，而干重整的活化能则略有下降（约15%）。
The kinetic behavior of CrOx sites supported on Fe doped CeO2 was studied for CO2-assisted propane oxidative dehydrogenation. The support was synthesized via a co-precipitation method of Fe and Ce precursors while wetness impregnation was used to deposit the CrOx species. XRD and Raman analysis confirmed the presence of dispersed CrOx sites on the surface of the support at a low loading while small Cr2O3 nanoparticles were found at high loadings. The addition of CrOx sites reconstructs the available surface oxygen sites and enhances the reducibility of the catalyst as confirmed by H2-TPR measurements. Herein, we show that the CrOx based catalysts outperform the parent support at low reaction temperatures both from a propane conversion and propylene selectivity perspective. At elevated temperatures, the effect of CrOx sites on the propylene production diminishes since propane dry reforming is dominant. A Langmuir–Hinshelwood kinetic model was developed based on 14 elementary steps to account for the dominating reaction pathways, i.e. propane dehydrogenation, reverse water gas shift and dry reforming. The regressed kinetic data showed that the incorporation of CrOx on the support decreases the activation energy of propane dehydrogenation by 60–75% while a small decrease in the activation energy of dry reforming was noted (∼15%).