Abstract:

Poly(oxy-1,2-ethanediyl)methylphosphonate(PEMP) as a good flame retardant has lots of benefits such as non-toxic, low smoke, high phosphorus content and better flame retardant effects. γ-Al₂O₃ is a good catalyst for the condensation of ethylene glycol (EG) and dimethyl phosphate (DMMP) to produce PEMP. However, since γ-Al₂O₃ is easy to absorb CO₂ and water to reduce its catalytic activity, activation is needed before use. The activation temperature affects the catalytic activity of γ-Al₂O₃. In this paper, γ-Al₂O₃ was activated at different temperatures from 300 ,400, 500, 600, 700 and 800 ℃. γ-Al₂O₃ crystal form was analyzed by X-ray difraction (XRD) and its specific surface area, pore diameter and pore volume were measured by Brunauer-Emmett-Teller (BET) method. The change of infrared absorption was analyzed by Fourier transfer infrared (FTIR). The relative contents of Brønsted acid and Lewis acid sites in γ-Al₂O₃ were determined by pyridine adsorption-FTIR. The purity and viscosity of PEMP catalyzed by γ-Al₂O₃ were compared, and the optimal activation temperature of γ-Al₂O₃ was found to be 400, 500 and 600 ℃. At this time, γ-Al₂O₃ is a typical γ-Al₂O₃ with large specific surface area and small pore diameter, and the obtained PEMP product has the highest purity.

Key words: poly(oxy-1,2-ethanediyl)methylphosphonate, γ-Al₂O₃, activation temperature, catalyzed activity