in ziegler-natta olefin polymerization, the pore architecture of catalysts plays a crucial role in catalyticperformances and polymer properties. while the type of preparation routes (such as chemical reaction andsolution precipitation) greatly affects the catalyst pore architecture as a result of different solidification mechanisms,the modification of the pore architecture within a given route ...

Developing selective polymerizations from complex monomer mixtures is an important challenge. Here, dinuclear catalysts allow selective polymerization from mixtures of sterically hindered tricyclic anhydrides, carbon dioxide and epoxides to yield well-controlled copoly(ester-carbonates). Surprisingly, two very similar homogeneous catalysts differing only in the central metal, zinc versus magnes...

A series of cyclometalated Z-selective ruthenium olefin metathesis catalysts with alterations to the N-heterocyclic carbene (NHC) ligand were prepared. X-Ray crystal structures of several new catalysts were obtained, elucidating the structural features of this class of cyclometalated complexes. The metathesis activity of each stable complex was evaluated, and one catalyst, bearing geminal dimet...

The first kinetically controlled, highly trans-selective (>98%) olefin cross-metathesis reaction is demonstrated using Ru-based catalysts. Reactions with either trans or cis olefins afford products with highly trans or cis stereochemistry, respectively. This E-selective olefin cross-metathesis is shown to occur between two trans olefins and between a trans olefin and a terminal olefin. Addition...

Reusable silica supported perchloric acid and potassium bisulphate have been prepared and explored as green catalysts for thiocyanation of aromatic compounds under conventional and solvent free microwave assisted conditions. The microwave assisted protocol exhibited remarkable rate accelerations and offered selective thiocyanation of aromatic and hetero aromatic compounds in good yields. Reacti...

The field of heterogeneous catalysis has received a remarkable amount of interest from scientific and industrial perspectives because of its enormous impact on the world's economy: more than 90% of chemical manufacturing processes use catalysts. Catalysts are also essential in converting hazardous waste into less harmful products (car exhaust) and in generating power (fuel cells). Yet in all ap...

Research development of processes for refining bio-oils is becoming increasingly popular. One issue that these processes possess is their high requirement for H2 gas. In response, researchers must develop catalysts that perform deoxygenation while minimizing H2 consumption-selective deoxygenation. Unlike traditional deoxygenation processes, selective deoxygenation reactions and catalysts repres...

The decomposition of a Z-selective ruthenium metathesis catalyst and structurally similar analogues has been investigated utilizing X-ray crystallography and density functional theory. Isolated X-ray crystal structures suggest that recently reported C-H activated catalysts undergo decomposition via insertion of the alkylidene moiety into the chelating ruthenium-carbon bond followed by hydride e...

Palladium, platinum, and ruthenium supported on activated carbon were used as catalysts for the selective hydrogenation of 1-heptyne, a terminal alkyne. All catalysts were characterized by temperature programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. TPR and XPS suggest that the metal in all catalysts is reduced after the pretreatme...