Carbon sorbent for removal of metal catalysts from pharmaceuticals
The present invention relates to a carbon sorbent the can selectively remove platinum-group metals and other heavy metals such as tin without co-removing organic synthesis products including pharmaceutical intermediates and finished Active Pharmaceutical Ingredients (APIs). The carbon sorbents of the present invention are made from low-cost, high purity starting materials and the resulting carbon sorbents are also very pure. The carbon sorbents possess a combination of certain nitrogen and phosphorous groups combined with mesoporosity (2 to 50 nm diameter pores) that proves the high metal adsorption.
1. A carbon sorbent for removing metals from an active pharmaceutical ingredient (API) organic reaction product, the carbon sorbent comprising:
(a) a nitrogen content of at least 3 weight %, which is present in the form of pyridine, pyridone, pyrrole or N—P bonds;
(b) an oxygen content of between 7 weight % and 16 weight %;
(c) a phosphorous content of at least 0.8 atom % as measured by X-ray photoelectron spectroscopy;
(d) a BET surface area of between 200 and 1700 meters squared per gram;
(e) a mesopore volume of at least 0.05 cubic centimeters per gram, wherein mesopores have a diameter of from 2 to 50 nanometers;
(f) a platinum-group metal uptake of at least 83% from a solution of 1.3 ppm platinum-group metal in an organic solvent with an active pharmaceutical ingredient (API) organic reaction product present in the organic solvent at a concentration of 1.0 grams of the active pharmaceutical ingredient (API) organic reaction product per 0.5 grams of the carbon sorbent, and wherein less than 1% of the active pharmaceutical ingredient (API) organic reaction product is adsorbed by the carbon sorbent from the organic solvent simultaneously with the platinum-group metal uptake;
wherein the platinum-group metal is-palladium; and,
(g) a pH of at most 3.1.
2. The carbon sorbent of claim 1 , further comprising: an ash content of at most 1.0 weight %.
3. The carbon sorbent of claim 2 , further comprising: less than 0.1 atom % Na and less than 0.1 atom % K as measured by X-ray photoelectron spectroscopy.