结晶Ⅱ型聚磷酸铵制备过程中氨的作用研究

Study on the role of ammonia in preparation of crystal formⅡammonium polyphosphate

研究结晶Ⅱ型聚磷酸铵制备过程中通氨工艺条件对产物性质的影响。以五氧化二磷、磷酸氢二铵、尿素为原料，在不同的通氨条件下制备结晶Ⅱ型聚磷酸铵，用FT—IR和XRD来分析晶型及杂质，并测定了结晶Ⅱ型聚磷酸铵的水溶性与pH。结果表明，通氨条件对制得结晶Ⅱ型聚磷酸铵的纯度、水溶性以及pH都有影响。在250℃开始通氨，维持氨压为0．1MPa，转晶氨化温度为300℃，氨化90～150min为最优条件。认为聚磷酸铵的水溶性并不简单地与晶型有关，还可能与氨在聚磷酸铵中的存在形式有关。

The effects of technological conditions of aerating ammonia in the preparation course of crystal form Ⅱ ammonium polyphosphate （ APP Ⅱ ） on the properties of the products were studied. APP Ⅱ was prepared with phosphorus pentoxide, diammonium hydrogen phosphate and urea under different technological conditions of aerating ammonia. Crystal forms and impurities were characterized by FT - IR and XRD. Water - solubility and pH of APP Ⅱ were tested as well. The results showed that the technological conditions of aerating ammonia have impacts on purity, water - solubility and pH of APP Ⅱ. The optimal conditions of aerating ammonia are ： initial temperature to aerate ammonia at about 250 ℃; maintain ammonia pressure at 0.1 MPa;final crystal form transformation and amination at 300 ℃for 90 - 150 rain. The water - solubility of APP Ⅱ is not only relative with crystal forms, but also impacted by the state of ammonia in APP.