The Heterogeneous Catalysts For The Synthesis Of Ethylene Diamine Tetra(Methylene Phosphonic Acid)

According to the conventional manufacturing method, the aminomethylenephosphonic acids are synthesized by the Mannich reaction, used amines and formaldehyde, phosphorus trichloride(or phosphite) as reactants. The reaction is generally catalyzed by the homogeneous catalysts like hydrochloric acid, sulfuric acid etc, at a temperature above 100?. Traditional homogeneous catalysts are highly corrosive, difficult to separate from the products, non-recovery, often cause serious pollution and other drawbacks.The main work of this paper is to transfer the homogeneous catalysis Mannich reaction to a heterogeneous catalysis one, by using the acid functionalized silica catalysts, which could be recycled and reused conveniently.Propyl sulfonic acid group and phenyl sulfonic acid group functionalized silica were obtained by treating the silica gel with organic functional siloxanes. After that the structural characterization and performance testing were carried out. Both of the two acid functionalized silica gels have good catalytic activity, in which the catalytic activity of silica-propyl sulfonic acid functional was stronger than that of the phenyl sulfonic acid functionalized silica gel. Compared with homogeneous catalysts, these two acid functionalized silica gels' catalytic activity were close to the sulfuric acid. The acid-functionalized silica catalysts had good resistance to solvent removal, after five runs the performance was not significantly decreased. The specific surface area of the propyl sulfonic acid group functionalized silica was 456 m2/g, the number of acidic sites was 0.63 mmol/g, the specific surface area of the phenyl sulfonic acid-functionalized silica gel was 395 m2/g, the number of acidic sites was 0.42 mmol/g. IR test results showed that functional groups were successfully anchored onto the silica surface.Mesoporous silica SBA-15 was prepared by using P123 as a soft template, and then the SBA-15 was grafted with propyl sulfonic acid group and phenyl sulfonic acid group to get SBA-15-pr-SO3 H and SBA-15-ph-SO3 H. Then characterized and performance testing were carried out. Both of the two functionalized SBA-15 catalysts had good catalytic activity, in particular at the temperature of 80?, the conversion rate could be over 90%, significantly better than that of the functionalized silica gel and homogeneous catalysts. The catalytic activity of the SBA-15-pr-SO3 H was stronger than that of the SBA-15-ph-SO3 H. The acid-functionalized SBA-15 catalysts had good resistance to solvent removal, after five runs the performance was not significantly decreased. Small angle XRD and TEM results showed that the acid-functionalized mesoporous silicas have a planar hexagonal structure, which confirm then are SBA-15. The specific surface area of SBA-SO3 H was 723 m2/g, with a pore size of 3.8 nm, the number of acidic sites was 1.25 mmol/ g. The specific surface area of the SBA-15-ph-SO3 H was 556 m2/g, with a pore size of 4.9 nm, the number of acidic sites was 0.93 mmol / g.