Nickel metal particle production
Methods are described herein that involve rotating or gently mixing nickel(II)-containing particles in a reaction vessel while heating the particles and flowing a reducing atmosphere through the reaction vessel for a time sufficient to generate free-flowing nickel metal (Ni(0)) from the nickel(II)-containing particles.
1. A method comprising:
(a) calcining first nickel(II)-containing particles in an atmosphere comprising oxidizing constituents to generate second nickel(II)-containing particles; and
(b) reducing the second nickel(II)-containing particles in a reducing atmosphere while rotating or turning the second nickel(II)-containing particles in a rotary processor at 275° C. to 360° C. for a time sufficient to generate a free-flowing particulate nickel metal (Ni(0)) product from the second nickel(II)-containing particles, wherein the reducing atmosphere is free of added water or steam not produced by the reducing, and wherein a H 2 /Ni molar ratio is employed during the reducing step of between about 1.9 and 2.5;
wherein the free-flowing particulate nickel metal (Ni(0)) product is two to seven times more active for complexation with a monodentate phosphorus-containing ligand, a bidentate phosphorus-containing ligand, or a combination thereof, than is a nickel metal product generated by hydrogen reduction with added water or steam that is not generated by the hydrogen reduction.
2. The method of claim 1 , wherein calcining comprises heating the first nickel(II)-containing particles in an atmosphere comprising oxidizing constituents at a temperature of 350° C. to 600° C. for a time sufficient to remove volatile components from the first nickel(II)-containing particles.
3. The method of claim 2 , wherein the time sufficient to remove volatile components from the first nickel(II)-containing particles comprises about 10 minutes to six hours.
4. The method of claim 1 , wherein a H 2 /Ni molar ratio is employed during the reducing step of between about 2.0 to about 2.4.
5. The method of claim 1 , wherein a H 2 /Ni molar ratio is employed during the reducing step that is greater than 2.
6. The method of claim 1 , wherein the time sufficient to generate free-flowing particulate nickel metal (Ni(0)) product during the reducing step is 0.5 hour to 1.5 hour.
7. The method of claim 1 , wherein the particulate nickel product has a BET SSA (m 2 /gram) value of at least 8 m 2 /gram.
8. The method of claim 1 , wherein the free-flowing particulate nickel metal (Ni(0)) product is two to seven times more active for complexation with Ligand (A) to generate a catalyst for hydrocyanation of unsaturated nitriles to dinitriles, than is a nickel metal product generated by hydrogen reduction with added water or steam that is not generated by the hydrogen reduction, wherein Ligand (A) has the following structure: