Disclosed are a catalyst system capable of selectively oligomerizing olefins including ethylene and a method for preparing an olefin oligomer by using the same and, specifically, a novel catalyst system capable of trimerizing and tetramerizing olefins, unlike olefin oligomerization catalyst systems that have been reported so far, and a method for preparing an olefin oligomer by using the same. The present invention provides a catalyst system for olefin oligomerization, the catalyst system comprising: a ligand compound represented by chemical formula 1 or 2; a chromium compound; a metal alkyl compound; and an aliphatic or alicyclic hydrocarbon solvent.

The invention relates to a process for the metathesis of olefins implemented with a catalyst comprising a mesoporous matrix and at least the elements molybdenum and silicon, said elements being incorporated into said matrix by means of at least one precursor comprising molybdenum and silicon and having at least one sequence of SiOMo bonds.

Disclosed herein is method for producing an iron dinuclear complex having two iron atoms bonded to each other via one oxygen atom and a ligand structure containing a Schiff base, a method which can produce an ester compound in high yield by the transesterification of an alcohol compound with a carboxylate ester even in the case where the raw material alcohol has a tertiary hydroxyl group which is usually difficult to esterify by transesterification, and a method which can produce a wholly esterified compound by transesterification catalyzed by an iron complex.

The present disclosure provides catalyst compounds including a nonsymmetric bridged amine bis(phenolate), catalyst systems including such, and uses thereof. Catalyst compounds, catalyst systems, and processes of the present disclosure can provide high comonomer content and high molecular weight polymers having narrow Mw/Mn values, contributing to good processability for the polymer itself and for the polymer used in a composition.

Disclosed herein is a method for selectively reducing, using electrical energy, CO.sub.2 to formic acid, a catalyst for use in the method, and an electrochemical reduction system. The method for producing formic acid by electrochemically reducing carbon dioxide of the present invention includes (a) reacting carbon dioxide with a metal complex represented by formula (1), and (b) applying a voltage to a reaction product of the carbon dioxide and the metal complex represented by formula (1): ##STR00001##

Highly quantitative methods for determining the concentration of residual phase transfer catalysts (PTCs) in radiotracer or radiopharmaceutical doses are described. The methods comprise mixing aliquots of the doses that can contain residual PTCs with a sodium and/or potassium salt; extracting a residual PTC/salt complex into an organic phase; and detecting the amount of PTC/salt complex in the organic phase. The detecting can involve visual colorimetry or measuring the absorbance or transmittance of the organic phase when the sodium and/or potassium salt comprises a chromophoric ion, or measuring the resistance of the organic phase. Also described are devices for use in performing the methods.

Aspects of the present invention concern the ring-opening copolymerization (ROCOP) of aromatic anhydrides and epoxides, such as terpene oxides, using sustainable starting materials, as well as the resulting polyester products having an unusually high glass transition temperature and low dispersity.

A field of asymmetric catalytic synthesis, and in particular a preparation method for a high optical indoxacarb intermediate includes reacting 5-chloro-2-methoxycarbonyl-1-indanone ester (or indanone ester for short) with an oxidizing agent in the presence of a chiral Zr-salen polymer to obtain an indoxacarb intermediate (2S)-5-chloro-2,3-dihydro-2-hydroxy-1-oxo-1H-indole-2-carboxylic acid methyl ester. The yield is stabilized between 86% and 90%, and the S-enantiomer content is up to 99%. Such catalyst can replace catalysts such as cinchonine, and greatly increase the content of the effective S-enantiomer of the indoxacarb, so that the content of the hydroxyl intermediate S-enantiomer of the indoxacarb is raised from 75% to 99% or more. In addition, the chiral Zr-salen polymer catalyst is recycled without retreatment, and can be recycled at least 5 times or more, greatly reducing the production cost and laying a foundation for the industrial production of high quality indoxacarb.

A method of aerobic depolymerization of fiber-reinforced polymer (FRP) composites using sustainable reagents and conditions. A cured matrix is digested into soluble monomers and oligomers by catalytic aerobic oxidation. Carbon fibers are removed for re-use, then the remaining material is treated and valuable monomers are isolated. The isolated monomers can be converted back into resin precursors for re-use. The method solves the problem created because the typically irreversible cure reaction impedes recycling and re-use of FRP composites.

Disclosed herein is method for producing an iron dinuclear complex having two iron atoms bonded to each other via one oxygen atom and a ligand structure containing a Schiff base, a method which can produce an ester compound in high yield by the transesterification of an alcohol compound with a carboxylate ester even in the case where the raw material alcohol has a tertiary hydroxyl group which is usually difficult to esterify by transesterification, and a method which can produce a wholly esterified compound by transesterification catalyzed by an iron complex.