Ligand tethering by ion-exchange for the immobilization of homogeneous catalysts

A Rh phosphine complex, derived from the Wilkinson’s catalyst, has been immobilized by ion-exchange on the ammonium form of a Al-MCM-41 sample. Ammonium ions have been exchanged by cholamine ions, which act as an amine ligand, and then the Wilkinson’s catalyst has been immobilized by substitution of a phosphine ligand by the anchored amine. This is a novel immobilization procedure, as a ligand, instead of the whole complex, is tethered to the support by ion exchange. The obtained hybrid catalyst has been characterized by Elemental Analysis, DRIFTS and XPS. The quantitative exchange of ammonium by cholamine and coordination of Rh to amines has been observed. Most of the anchored Rh is considered to be coordinated to the ligand tethered to the support and a small proportion seems to be interacting with the protonated ligand or with the support surface. The catalyst has been tested in the hydrogenation of cyclohexene and in the hydroformylation of 1-octene. In the first case the catalyst is active and reusable, while a strong Rh leaching takes place in the second one.

Evaluation of ion exchange softening and corrosiveness of drinking water.

Mode of access: Internet.

Removal of scale-forming constituents from saline water by ion exchange -equilibrium conditions,

Sea Water Conversion Laboratory report no. 63-2.

Electrolytic precipitation of uranium from ion exchange eluates /

"Date Declassified: September 23, 1955."

Investigations of the ion exchange resins in use in South Africa : topical report /

"Date Declassified: September 23, 1955."

Electrolytic precipitation of uranium from flowing ion exchange eluates : topical report /

"Date Declassified: September 23, 1955."

The electrolytic recovery of uranium and vanadium from carbon leach liquors by means of ion exchange membranes /

"Date Declassified: September 23, 1955."

Recovery of uranium by ion exchange resins : topical report /

"Contract AT(49-1)-535."

The electrolytic recovery of uranium from Vitro leach liquor by means of ion exchange membranes /

The investigation of the electrolytic precipitation of uranium from a sample of acid leach liquor in an ion exchange membrane cell has been conducted on leach liquor from the Vitro Co. This leach liquor can be treated by the above means to precipitate essentially all the uranium and simultaneously to produce additional acid which may be used for further leaching.

Electrolytic precipitation of uranium from Belgian Congo ion exchange resin eluates in a three compartment cell /

Electrolytic precipitation of uranium from ion-exchange resin eluates has been investigated in a three-compartment cell. A relatively low-energy consumption is required and anodic attack is reduced to a negligible quantity. During the precipitation, acid is produced in sufficient quantity for use as eluant for subsequent eluting operations. The recovered uranium is in the form of a rapid settling, fast filtering precipitate which is easily washed with water to reduce the chloride content to a tolerable concentration.

The prevention of cobalticyanide poisoning of ion exchange resins used on South African gold ore residue leach liquors /

"Date Declassified: September 23, 1955."

The electrolytic migration of uranium from acid leach liquors by means of ion exchange membranes /

"Date Declassified: September 23, 1955."

Use of ion exchange for the separation of uranium from ions interfering in its colorimetric determination /

"Date Declassified: September 23, 1955."

Application of the ion exchange separation of uranium to the analysis of ores /

"Date Declassified: September 23, 1955."