The results of decades of studies on the Phillips chromium (Cr)/silica polymerization catalyst are briefly summarized. The application of several characterization methods has allowed a detailed knowledge of the structure and reactivity of Cr centres to be obtained. In particular, many aspects of this apparently simple single-site catalyst, including the heterogeneity, the modification of the li...

High throughput screening (HTS) of a 205 member Schiff base salicylaldimine ligand library derived from salicylaldehydes bearing bulky ortho-substituents, i.e., 9-anthracenyl, 1,4,5,8-tetramethylanthracenyl or triptycenyl, reacted in-situ with (p-tolyl)CrCl2(thf)3, identified two new classes of highly active chromium based systems for the oligomerization and polymerization of ethylene, respecti...

A diamine-bis(phenolate) chromium(III) complex, {CrCl[O2NN'](BuBu)}2 catalyzes the copolymerization of propylene oxide with carbon dioxide. The synthesis of this metal complex is straightforward and it can be obtained in high yields. This catalyst incorporates a tripodal amine-bis(phenolate) ligand, which differs from the salen or salan ligands typically used with Cr and Co complexes that have ...

The catalytic effects of chromium (Cr) on the direct nitridation of silicon (Si) and morphology of nitridation product were investigated. Cr dramatically improved the conversation of Si to silicon nitride (Si3N4). The complete conversion was achieved at 1350 °C upon addition of 1.25 wt% Cr. This temperature was much lower than that required in the case without using a catalyst. Meanwhile, Cr pl...

Planar chiral h6-arene chromium(0) complexes are finding increasing application in the synthesis of enantioenriched compounds by serving as enantiopure starting materials or ligands for catalytic asymmetric processes.[1,2] Whereas early methods of generating enantiopure 1,2-disubstituted h6-arene chromium(0) complexes relied on resolution of racemates,[3] many methods have been developed recent...

the mesoporous molecular sieve mcm-41 was covalently grafted with 3-chloropropyl trimethoxylsilane and then was reacted with [cr(salpr)(h2o)]cl, (salpr = n,n'-bis(3-salicylidenaminopropyl)amine) to afford mcm-41 containing cr(salpr) moiety, cr(salpr)mcm-41. powder x-ray diffraction and nitrogen adsorption-desorption analyses revealed that not only the textural characteristics of the support wer...

Biomass plays an important role in the green manufacture of high value-added chemicals. Among them, conversion furfural (FFA) into 2-methylfuran (2-MF), catalyzed by a copper-chromium catalyst, is its industrial application. However, use chromium limited due to toxicity and pollution environment. In this paper, Cu/SiO2 prepared ammonia evaporation method, shows better catalytic performance comp...