6850-36-8Relevant articles and documents
N-substituted diphosphinoamines: Toward rational ligand design for the efficient tetramerization of ethylene
Kuhlmann, Sven,Blann, Kevin,Bollmann, Annette,Dixon, John T.,Killian, Esna,Maumela, Munaka C.,Maumela, Hulisani,Morgan, David H.,Pretorius, Marie,Taccardi, Nicola,Wasserscheid, Peter
, p. 279 - 284 (2007/10/03)
Bis(diphenylphosphino)amine (PNP) ligands with different alkyl and cycloalkyl substituents attached to the N atom of the ligand backbone were synthesised and tested together with chromium as ethylene tetramerization catalysts. On activation with a methylaluminoxane-based activator, the catalysts displayed good activity and selectivity toward 1-octene and 1-hexene, with the best ligand systems containing cyclopentyl or cyclohexyl moieties. In addition, it was established that substitution at the 2 position of the cyclohexyl skeleton and, more importantly, an increase in steric bulk at that point, led to a drastic reduction of side product formation (i.e., methyl- and methylenecyclopentane). Interestingly, additional methyl substitution in the 6 position of the cyclohexyl ring changed the selectivity of the catalyst from predominantly tetramerization to a 1:1 mixture of 1-hexene and 1-octene. Structurally similar ligands, such as cyclohexylmethyl and cyclohexylethyl PNP, were also tested and were also found to yield efficient tetramerization catalysts. It was concluded that structural fine tuning of the N-alkyl moiety of the PNP ligand is essential for obtaining efficient tetramerization catalysts, with the best systems achieving combined selectivities as high as 88% (1-octene and 1-hexene) with exceptionally high activities exceeding 2,000,000 g/(g-Cr h).
KINETICS FOR SIMULTANEOUS HDS, HDN AND HYDROGENATION MODEL REACTIONS ON A Co-Mo/Al2O3 CATALYST
Zeuthen, Per,Stolze, Per,Pedersen, Ulla B.
, p. 985 - 996 (2007/10/02)
A kinetic analysis of simultaneous hydrodesulfurization (HDS) of dibenzothiophene (DBT), hydrodenitrogenation (HDN) of indole (IN) and hydrogenation (HYD) of naphthalene (NAP) is carried out.These compounds represent the major functional groups in heavy petroleum feeds.The goal of these experiments is to simulate the performance of a commercial catalyst with more complex feedstocks.The purposes are to determine the competitive inhibition effects of the various reactants as well as to investigate a microscopic model which can be generalized to more realistic feedstocks.Kinetic data are generated over a CoMo/Al2O3 catalyst in a temperature range of 260-350 deg C and total pressure of 25-81 105 Pa.The partial pressures of hydrogen and the other reactants are varied individually.From the data, a kinetic model is developed based on the competitive chemisorption of reactants, intermediates and products on identical surface sites.The kinetic model developed accounts for rates of appearance of the products and rates of disappearance of DBT, NAP and IN.The results suggest that compounds containing sulfur, nitrogen, aromatics or aliphatics are adsorbed with very different strength.
Preparation of primary aromatic amines from cyclic alcohols and/or ketones
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, (2008/06/13)
Aromatic amines, in particular substituted amines, are obtained from corresponding alicyclic alcohols or ketones, in one step, by amination and dehydrogenation with ammonia in the presence of hydrogen and of a palladium catalyst which also contains zinc or cadmium.