The Research On Ammonium Ion Exchange Process Of Mordenite Zeolite Production

Mordenite zeolite is regard as important catalyst and absorption-desorption material. Its structure means it has great selectivity, absorbability, catalytic performance. Mordenite zeolite with high Si/Al ratio has better water-thermal stability and anti-acid performance. It is widely used in the oil refinery industry and fine chemicals industry.The study here explores Na-M zeolite that Si/Al ration is more than 20. The ion-exchange process uses NH4NO3 as the solute. Using orthogonal experiment analysis and combing with the producing process get the optimum condition as below:the solution concentration of NH4NO3 is 0.8mol·L-1, ion exchange temperature is 90℃, ion exchange time is 2 hours. In this condition, the maximum exchange ratio is about 70%. The sequence of orthogonal factors is CNH4NO3> Tex >tex.After several experiments, the exchange ratio of Na+ after triple exchange process is 98.06%. And after four times exchange process, the exchange ratio of Na+ becomes 99.05%. According to the quality control index, four times exchange process will meet the requirement. The ammonium ion exchanged incompletely in the Na-M zeolites is confirmed from the NH4+-Na+ ion exchange isothermal curve. Using X-ray diffraction to characterize mordenite zeolite with different Na+exchange ratio shows that the structure of mordenite framework has no obvious change.In the industrialized producing process of mordenite zeolite, we researched to use the nitrogen acid to absorb the templates which is liquid ammonia. Compared with two different improved Na+ion exchange process, we found that the ion exchange effect reduced with the increase Na+ concentration and confirmed the optimum method. We decided to reuse the third time exchange solution to the first time exchange process and reuse the forth to the first. And we successfully utilized the nitrogen acid solution which absorbed ammonia into the third ammonium ion exchange process. From the application in industry, the process mentioned above will absorb about 99% ammonia emission, reduce the amount of NH4NO3 utilized about 75%, cut down the concentration of NH4-N about 80% and NO3-N about 75% in the organic waste water and shorten the duration of ion exchange process about 50%. Through the improvement of the ion exchange process, the pollutant is reduced along with the cost. And the difficulty of waste water treatment is decreased. With the noval process, the producing flexibility is improved and the labour intensity is decreased.Furthermore, the practicability of using (NH4)2SO4 to replace NH4NO3 is confirmed preliminarily. We give some suggestion to improve filter and cleaning process after ion exchange to promote the cleaning effect.