Shetty Manish, Zanchet Daniela, Green William H, Román-Leshkov Yuriy
Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
Institute of Chemistry, University of Campinas, Campinas, SP-13083-970, Brazil.
ChemSusChem. 2019 May 21;12(10):2171-2175. doi: 10.1002/cssc.201900664. Epub 2019 Apr 18.
Strontium-substituted lanthanum cobaltite (La Sr CoO ) matrix-stabilized Co /Co catalytic sites were prepared, which present tunable C-O and C-C hydrogenolysis activity for the vapor-phase upgrading of oxygenated arenes. Co sites associated with oxygen vacancies were favored at low temperatures and performed selective C-O hydrogenolysis, in which Sr-substitution facilitated oxygen vacancy formation, leading to approximately 10 times higher reactivity compared to undoped LaCoO . Co sites were favored at high temperatures and performed extensive C-C bond hydrogenolysis, generating a wide range of alkanes. The lower reaction order with P (1.1±0.1) for C-C hydrogenolysis than for C-O hydrogenolysis (2.0±0.1) led to a high selectivity towards C-C hydrogenolysis at low P . The Co O surfaces featured a narrower temperature window for obtaining the respective optimal Co and Co pairs compared to analogous perovskite surfaces; whereas, the perovskite matrix stabilizes these pairs for selective C-O and C-C hydrogenolysis. This stabilization effect offers an additional handle to control reactivity in oxide catalysts.
制备了锶取代的钴酸镧（LaSrCoO）基质稳定的Co/Co催化位点，其对含氧芳烃的气相升级具有可调的C-O和C-C氢解活性。与氧空位相关的Co位点在低温下更有利，并进行选择性C-O氢解，其中Sr取代促进了氧空位的形成，导致与未掺杂的LaCoO相比反应活性提高约10倍。Co位点在高温下更有利，并进行广泛的C-C键氢解，生成多种烷烃。C-C氢解的反应级数（1.1±0.1）低于C-O氢解（2.0±0.1），导致在低P下对C-C氢解具有高选择性。与类似的钙钛矿表面相比，CoO表面获得各自最佳Co和Co对的温度窗口更窄；而钙钛矿基质稳定这些对以进行选择性C-O和C-C氢解。这种稳定作用为控制氧化物催化剂的反应活性提供了额外的手段。
