Patent ID: 7399885

Claim:
A method for preparing hydroxylamine, comprising the steps of: (i) pretreating an acidic buffer solution comprising acidic buffer reagents, nitric acid or nitrate salts, and metal impurities, with the compounds having a functional group represented by formula (I), wherein R 2 and R 3 are, independently, those selected from the group consisting of hydrogen atom, phenyl, phenyl substituted by C 1-6 alkyl, phenyl substituted by nitro group, phenyl substituted by amino group, phenyl substituted by halogen, heteroaryl having 1 to 3 heteroatoms, —XR 4 , and polymers; of those, the heteroatom is selected from the group consisting of N, O and S atoms, the heteroaryl is aryl having 6 to 18 carbons, X is a chemical bond or alkylene having 1 to 6 carbons; R 4 is selected from the group consisting of hydrogen atom, phenyl, heteroaryl having 1 to 3 heteroatoms, and polymers, and at least one of R 2 , and R 3 is not hydrogen; and (ii) reducing nitrate ions in the acidic buffer solution with hydrogen to give hydroxylamine in the presence of catalysts.