Energy-efficient metal recovery and separation processes from a mixture of valuable metals are vital to the metallurgy and recycling industries. Oxalate has been identified as a sustainable reagent...

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Metal Recovery Using Oxalate Chemistry: A Technical Review

@ A process for preparing hydrocarbon-soluble transition metal salts of organic carboxylic acids having improved properties wherein the transition metal is one capable of having a multiplicity of oxidation states is described. The process comprises the steps of (a) providing at least one transition metal compound wherein the transition metal is at one of its higher positive oxidation states, (b) treating said transition metal compound with at least one inorganic reducing agent forming an intermediate containing the transition metal in a lower positive oxidation state, and (c) reacting said intermediate with at least one organic carboxylic acid containing at least 5 carbon atoms to form the transition metal salt of said carboxylic acid. The transition metal salts prepared in accordance with the process of the invention are useful in a variety of applications including resins, inks, paints, lubricants and fuels.

Preparation of hydrocarbon-soluble transition metal salts of organic carboxylic acids

A process for preparing transition metal salt compositions of organic carboxylic acids having improved properties wherein the transition metal is one capable of having a multiplicity of oxidation states is described. The process comprises the steps of (a) providing at least one transition metal compound wherein the transition metal is at one of its higher positive oxidation states, (b) treating said transition metal compound with at least one reducing agent forming an intermediate containing the transition metal in a lower positive oxidation state, (c) reacting said intermediate with at least one organic carboxylic acid to form the transition metal salt of said carboxylic acid, and (d) mixing said transition metal salt formed in step (c) with (i) at least one antioxidant, or (ii) at least one additional metal salt wherein the additional metal is more electronegative than the transition metal, or (iii) mixtures of (i) and (ii). The transition metal salt compositions prepared in accordance with the process of the invention are useful in a variety of applications including resins, inks, paints, lubricants and fuels.

Preparation of transition metal salt compositions of organic carboxylic acids

A process is disclosed for the preparation of vanadium trineodecanoate to used as one component of a promoter used in conjunction with a catalyst to cure a polyester resin. Vanadium pentoxide is reacted or reduced in an acidic solution. The resultant mixture is heated and thereupon neodecanoic acid triethyl phosphate, paraformaldehyde and xylene are added. This solution is azeotropically distilled. Vanadium trineodecanoate is recovered in a xylene phase.

Synthesis of hydrocarbon soluble vanadium catalyst

Selective oxidation of α-hydroxy esters is one of the most important methods to prepare high value-added α-keto esters. An efficient catalytic system consisting of Zn(NO3)2/VOC2O4 is reported for catalytic oxidation of α-hydroxy esters with molecular oxygen. Up to 99% conversion of methyl DL-mandelate or methyl lactate could be facilely obtained with high selectivity for its corresponding α-keto ester under mild reaction conditions. Zn(NO3)2 exhibited higher catalytic activity in combination with VOC2O4 compared with Fe(NO3)3 and different nitric oxidative gases were detected by situ attenuated total reflection infrared (ATR-IR) spectroscopy. UV-vis and ATR-IR results indicated that coordination complex formed in Zn(NO3)2 in CH3CN solution was quite different from Fe(NO3)3; it is proposed that the charge-transfer from Zn2+ to coordinated nitrate groups might account for the generation of different nitric oxidative gases. The XPS result indicate that nitric oxidative gas derived from the interaction of Zn(NO3)2 with VOC2O4 could be in favor of oxidizing VOC2O4 to generate active vanadium (V) species. It might account for different catalytic activity of Zn(NO3)2 or Fe(NO3)3 combined with VOC2O4. This work contributes to further development of efficient aerobic oxidation under mild reaction conditions.

https://www.mdpi.com/1420-3049/24/7/1281/pdf

Novel Effect of Zinc Nitrate/Vanadyl Oxalate for Selective Catalytic Oxidation of α-Hydroxy Esters to α-Keto Esters with Molecular Oxygen: An In Situ ATR-IR Study

Vanadyl oxalate compounds, particularly vanadyl oxalate monohydrate and vanadyl oxalate sesquihydrate, are prepared by reacting vanadium pentoxide with oxalic acid dihydrate or anhydrous oxalic acid in an acetic acid solvent system.

William Novis Smith

Papers

Vanadyl oxalate compounds and process for producing same