Homogeneous olefin polymerization catalysts are activated in situ with a co-catalyst ([PhN(Me)2-H]+[B(C6F5)4]− or [Ph3C]+[B(C6F5)4]−) in bulk polymerization media. These co-catalysts are insoluble in hydrocarbon solvents, requiring excess co-catalyst (>3 eq). Feeding the activated species as a solution in an aliphatic hydrocarbon solvent may be advantageous over the in situ activation method. In this study, highly pure and soluble ammonium tetrakis(pentafluorophenyl)borates ([Me(C18H37)2N-H]+[B(C6F5)4]− and [(C18H37)2NH2]+[B(C6F5)4]−) containing neither water nor Cl− salt impurities were prepared easily via the acid–base reaction of [PhN(Me)2-H]+[B(C6F5)4]− and the corresponding amine. Using the prepared ammonium salts, the activation reactions of commercial-process-relevant metallocene (rac-[ethylenebis(tetrahydroindenyl)]Zr(Me)2 (1-ZrMe2), [Ph2C(Cp)(3,6-tBu2Flu)]Hf(Me)2 (3-HfMe2), [Ph2C(Cp)(2,7-tBu2Flu)]Hf(Me)2 (4-HfMe2)) and half-metallocene complexes ([(h5-Me4C5)Si(Me)2(k-NtBu)]Ti(Me)2 (5-TiMe2), [(h5-Me4C5)(C9H9(k-N))]Ti(Me)2 (6-TiMe2), and [(h5-Me3C7H1S)(C10H11(k-N))]Ti(Me)2 (7-TiMe2)) were monitored in C6D12 with 1H NMR spectroscopy. Stable [L-M(Me)(NMe(C18H37)2)]+[B(C6F5)4]− species were cleanly generated from 1-ZrMe2, 3-HfMe2, and 4-HfMe2, while the species types generated from 5-TiMe2, 6-TiMe2, and 7-TiMe2 were unstable for subsequent transformation to other species (presumably, [L-Ti(CH2N(C18H37)2)]+[B(C6F5)4]−-type species). [L-TiCl(N(H)(C18H37)2)]+[B(C6F5)4]−-type species were also prepared from 5-TiCl(Me) and 6-TiCl(Me), which were newly prepared in this study. The prepared [L-M(Me)(NMe(C18H37)2)]+[B(C6F5)4]−-, [L-Ti(CH2N(C18H37)2)]+[B(C6F5)4]−-, and [L-TiCl(N(H)(C18H37)2)]+[B(C6F5)4]−-type species, which are soluble and stable in aliphatic hydrocarbon solvents, were highly active in ethylene/1-octene copolymerization performed in aliphatic hydrocarbon solvents.
The simulation investigation on the availability of LNG plant with scenario of failure events and failure rate has been carried out. This study focuses on the availability, productivity, criticality induced by failure rate of major equipment. The methodologies for simulation such as the equipment classification of LNG plant and failure type and event schematic are established. The availability and mean time to repair have second order function profile in the all cases except general equipment, but these profiles have different inclination. The production and criticality of the specified LNG plant, simulated by Monte-Carlo algorithm, is located in the range of P = 86~ 92% and PL = 6~13%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.