Otroshchenko Tatiana, Fedorov Aleksandr, Zhang Qiyang, Linke David, Handzlik Jarosław, Schröder Mirjam, Corzilius Björn, Kondratenko Evgenii V
Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a D-18059 Rostock Germany
Cracow University of Technology, Faculty of Chemical Engineering and Technology ul. Warszawska 24 31-155 Kraków Poland.
Chem Sci. 2025 Jan 8;16(7):3141-3149. doi: 10.1039/d4sc06833e. eCollection 2025 Feb 12.
Although supported Mo-containing catalysts have been extensively investigated in the metathesis of ethylene with 2-butene to propene, the mechanisms of the formation and transformation of catalytically active Mo-carbenes in the course of the reaction are still not fully understood. The difficulties arise because only a tiny fraction of MoO species can form Mo-carbenes , making the detection of the latter by spectroscopic means very unlikely. Herein, purposefully designed steady-state and transient experiments including their kinetic evaluation and density functional theory calculations enabled us to elucidate mechanistic and kinetic details of the above reaction-induced processes in the metathesis reaction over a Mo/P/SiO catalyst at 50 °C. We established that, in parallel with the desired reaction cycle, molybdacyclobutanes also undergo reversible structural transformations which might be one of the reasons for low steady-state catalyst activity. Based on the results obtained, strategies for controlling the concentration of the inactive species and accordingly catalyst activity have been suggested and experimentally validated.
尽管负载型含钼催化剂在乙烯与2-丁烯复分解生成丙烯的反应中已得到广泛研究，但反应过程中催化活性钼卡宾的形成和转化机制仍未完全明晰。困难在于只有极小部分的MoO物种能形成钼卡宾，这使得通过光谱手段检测钼卡宾极不可能。在此，通过精心设计的稳态和瞬态实验，包括动力学评估和密度泛函理论计算，我们得以阐明在50°C下Mo/P/SiO催化剂上复分解反应中上述反应诱导过程的机理和动力学细节。我们确定，与期望的反应循环并行，钼环丁烷也会发生可逆的结构转变，这可能是稳态催化剂活性较低的原因之一。基于所得结果，已提出并通过实验验证了控制非活性物种浓度从而控制催化剂活性的策略。
