Direct Transformation of Ethylene into Propylene Catalyzed by a Tungsten Hydride Supported on Alumina: Trifunctional Single‐Site Catalysis

Ammonia and Dinitrogen Activation by Surface Organometallic Chemistry on Silica‐Grafted Tantalum Hydrides

“…[16] The increased loading possible on MCM-41 -(500) has also led to a better resolved 13 3 ], 95 ppm (CH 2 -tBu) and 247 ppm (=CH-tBu). [5] The use of silsesquioxane molecular models [19][20][21] and advanced NMR spectroscopic techniques such as J-resolved 2D SS NMR, in particular, have helped describe the molecular structure of the grafted species down to the extent of the small J C-H coupling of the methylidene ligand (vide infra).…”

“…When heated at 150°C under an atmosphere of dry H 2 , the grafted complexes 1a and 1b yield the supported tantalum hydrides 2, of which the major product is the monohydride, that is, [(ϵSiO) 2 . [5,6] The product of surface embedment [(ϵSiO) 3 Ta] is also present to a smaller extent. The coexistence of these species has been established spectroscopically by EXAFS, IR and solid-state MAS 1 H NMR spectroscopy ( Figure 1).…”

“…Studies in heterogeneous catalysis spanning over several decades have contributed to the assessment of SOMC as a viable route to high-performance catalysts. As examples of its success, one could mention systems such as silica-grafted olefin metathesis catalysts with a TON of 231000 in 1500 min for propene, [2] the trifunctional tungsten-based catalyst for direct conversion of ethylene to propylene [3] and the tantalum-based catalytic system for the non-oxidative coupling of methane to form ethane. [4] This final tantalum-based system, which contains at least the two surface tantalum hydride species, [(ϵSiO) 2 TaH] and [(ϵSiO) 2 TaH 3 ], [5] has displayed remarkable activity toward C-C and C-H bonds in both stoichiometric activation [6] and catalytic reactions such as alkane metathesis, [7] crossmetathesis between ethane and toluene, [8] and methane coupling to form ethane.…”

Conversion of Bioethanol to Propylene over ZSM-5 Zeolites

“…Recently, Basset et al reported that ethylene is transformed directly into propylene on the catalyst 22) , and proposed that a carbene (:CH2) complex formed on the surface reacts with ethylene to form propylene by crossmetathesis. In contrast, Beran et al reported that interaction of ethylene with the hydroxyl groups of HY zeolites, which leads to the formation of a stablecomplex, weakens the C C bond 23), 24) .…”

On the Origins and Development of “Surface Organometallic Chemistry”

“…(Figure 1.4 ). This is a major achievement, mainly due to Basset and his group, in surface organometallic chemistry because it has been thus possible to prepare " single site " catalysts for various known or new catalytic reactions [53] such as metathesis of olefi ns [54] , polymerization of olefi ns [55] , alkane metathesis [56] , coupling of methane to ethane and hydrogen [57] , cleavage of alkanes by methane [58] , hydrogenolysis of polyolefi ns [59] and alkanes [60] , direct transformation of ethylene into propylene [61] , etc. These topics are considered in detail in subsequent chapters.…”