Searles Keith, Siddiqi Georges, Safonova Olga V, Copéret Christophe
Department of Chemistry and Applied Biosciences , ETH Zürich , CH-8093 Zürich , Switzerland . Email:
Paul Scherrer Institute , CH-5232 Villigen , Switzerland.
Chem Sci. 2017 Apr 1;8(4):2661-2666. doi: 10.1039/c6sc05178b. Epub 2017 Jan 3.
Single-site gallium centers on the surface of silica are prepared grafting of [Ga(OSi(OBu))(THF)] on SiO followed by a thermolysis step. The resulting surface species corresponds to well-defined tetra-coordinate gallium single-sites, [([triple bond, length as m-dash]SiO)Ga(XOSi[triple bond, length as m-dash])] (X = -H or [triple bond, length as m-dash]Si) according to IR, X-ray absorption near-edge structure and extended X-ray absorption fine structure analysis. These gallium sites show high activity, selectivity and stability for propane dehydrogenation with an initial turnover frequency of 20 per h per gallium center, propylene selectivity of ≥93% and remarkable stability over 20 h. The stability of the catalyst probably results from site-isolation of the active site on a non-reducible support such as silica, diminishing facile reduction typical of GaO-based catalysts.
通过在SiO₂上接枝[Ga(OSi(OBu))₃(THF)]并经过热解步骤，制备了二氧化硅表面的单中心镓位点。根据红外光谱、X射线吸收近边结构和扩展X射线吸收精细结构分析，所得表面物种对应于明确的四配位镓单中心，即[([≡]SiO)Ga(XOSi[≡])]（X = -H或[≡]Si）。这些镓位点对丙烷脱氢表现出高活性、选择性和稳定性，初始转化频率为每小时每镓中心20次，丙烯选择性≥93%，且在20小时内具有显著的稳定性。催化剂的稳定性可能源于活性位点在诸如二氧化硅等不可还原载体上的位点隔离，减少了基于Ga₂O₃催化剂典型的容易还原的情况。
