Li Yuting, Zhu Zihan, Wu Xia, Ma Lei, Sun Xiaohui, Liu Qinggang
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Molecules. 2025 Apr 14;30(8):1746. doi: 10.3390/molecules30081746.
LaOCl-mediated ethane chlorination into 1,2-dichloroethane offers a promising pathway for low-temperature, large-scale ethane upgrading. However, under Cl-rich conditions, LaOCl undergoes detrimental chlorination into lanthanum chloride (LaCl), accompanied by extensive surface hydroxylation. Such severe structural evolution limits the practical application of La-based catalysts under industrially relevant conditions. In this study, an alumina-stabilized La catalyst was prepared via a coprecipitation method. We demonstrated that strong La-O-Al interactions effectively resist structural degradation of La species under reaction conditions, enabling the modified catalyst to maintain exceptional stability under high Cl concentrations. At a CH/Cl ratio of 4:9, the optimized catalyst achieves an ethane conversion of 61%, with 1,2-dichloroethane selectivity sustained above 74% for 12 h without noticeable deactivation. In contrast, the bulk LaOCl counterpart suffers from rapid over-chlorination, shifting product dominance to trichloroethane within 10 h. Advanced spectroscopy characterization reveals that selectivity loss in LaOCl originates from phase collapse into LaCl, whereas AlO stabilization preserves the metastable LaOCl phase in a highly dispersed state, ensuring selective C-Cl bond formation. These results highlight the critical role of stabilizing metastable oxychloride phases through robust metal oxide interactions, establishing a design framework for rare-earth catalysts in high-concentration chlorine environments.
氧化镧氯（LaOCl）介导的乙烷氯化生成1,2 - 二氯乙烷为低温、大规模乙烷升级提供了一条有前景的途径。然而，在富氯条件下，LaOCl会发生有害的氯化反应生成氯化镧（LaCl），同时伴随着广泛的表面羟基化。这种严重的结构演变限制了镧基催化剂在工业相关条件下的实际应用。在本研究中，通过共沉淀法制备了氧化铝稳定的镧催化剂。我们证明了强的La - O - Al相互作用在反应条件下能有效抵抗La物种的结构降解，使改性催化剂在高氯浓度下保持优异的稳定性。在CH/Cl比为4:9时，优化后的催化剂实现了61%的乙烷转化率，1,2 - 二氯乙烷选择性在12小时内保持在74%以上且无明显失活。相比之下，块状的LaOCl对应物则遭受快速的过度氯化，在10小时内产物优势就转移到了三氯乙烷。先进的光谱表征表明，LaOCl中的选择性损失源于相坍塌成LaCl，而AlO稳定化则将亚稳的LaOCl相保持在高度分散的状态，确保了选择性的C - Cl键形成。这些结果突出了通过强大的金属氧化物相互作用稳定亚稳氯氧化物相的关键作用，为高浓度氯环境中的稀土催化剂建立了一个设计框架。
