化学学报 ›› 2017, Vol. 75 ›› Issue (7): 679-685.DOI: 10.6023/A17040169 上一篇    下一篇

研究论文

水热条件下Y型沸石的转晶行为

胡成玉, 闫文付, 徐如人   

  1. 吉林大学化学学院 无机合成与制备国家重点实验室 长春 130012
  • 收稿日期:2017-04-19 出版日期:2017-07-15 发布日期:2017-06-08
  • 通讯作者: 闫文付 E-mail:yanw@jlu.edu.cn
  • 基金资助:

    项目受国家自然科学基金(Nos.21571075,21320102001,21621001)、国家重大研发计划(No.2016YFB0701100)和高等学校学科创新引智计划(No.B17020)资助.

Phase Transition Behavior of Zeolite Y under Hydrothermal Conditions

Hu Chengyu, Yan Wenfu, Xu Ruren   

  1. State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012
  • Received:2017-04-19 Online:2017-07-15 Published:2017-06-08
  • Contact: 10.6023/A17040169 E-mail:yanw@jlu.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos.21571075,21320102001,21621001),the National Key Research and Development Program of China (No.2016YFB0701100) and the Programme of Introducing Talents of Discipline to Universities (No.B17020).

系统研究了以KOH为结构导向剂,Y型沸石(HY和NaY)在水热条件下转晶为MER型沸石的行为.MER型沸石是硅铝比(Si/Al)在2~3之间且具有四种尺寸8元环孔道(3.1Å×3.5Å,2.7Å×3.6Å,3.4Å×5.1Å,3.3Å×3.3Å)的硅铝沸石分子筛,在小分子催化以及分离方面具有重要的潜在应用.传统水热法合成高结晶度MER型沸石需要7~10 d,将Y型沸石置于KOH的溶液中,经水热处理可在2 d内生成高结晶度的MER型沸石,而水热处理具有等价摩尔组成的无定形硅铝凝胶则得不到高结晶度MER型沸石的纯相.HY沸石可在100和150℃发生转晶,而NaY则只能在150℃发生转晶.KOH/SiO2比和H2O/SiO2比对Y型沸石的转晶行为有重大的影响,只有在最优KOH/SiO2比和H2O/SiO2比条件下才能生成高结晶度的MER型沸石.该转晶合成法显著缩短了MER型沸石的合成周期,对缩短其它有重大工业应用价值的沸石分子筛的合成周期有重要的借鉴意义.

关键词: 沸石, 水热合成, 转晶, Y型沸石, MER型沸石

The phase transition behavior of zeolite Y (HY and NaY) to zeolite MER in the KOH solution under hydrothermal conditions was systematically investigated.Zeolite MER has four types of 8-membered ring channels (3.1 Å×3.5 Å,2.7 Å×3.6 Å,3.4 Å×5.1 Å,3.3 Å×3.3 Å) and important potential applications in small molecule catalysis and separation.Seven to ten days are needed to synthesize highly crystalline zeolite MER with traditional hydrothermal synthesis.With phase transition of zeolite Y in the KOH solution under hydrothermal treatment,highly crystalline zeolite MER can be obtained within two days.The synthetic system contains zeolite Y (HY and NaY),KOH,and water,where KOH/SiO2 and H2O/SiO2 are changeable.Hydrothermally treating the equivalent amorphous aluminosilicate gel resulted in the mixture of zeolite MER and zeolite LTL (for HY) or zeolite CHA (for NaY) with low degree of crystallinity.Phase transition of HY can be conducted at either 100 or 150℃,whereas that of NaY can only be conducted at 150℃.As a common process for the hydrothermal phase transition of zeolite Y to zeolite MER in the absence of organic templates,potassium hydroxide was first dissolved into deionized H2O.After stirring at room temperature for 5 min,zeolite Y (HY or NaY) as aluminum and silicon sources was introduced into the potassium hydroxide solution.After further stirring for 1 h,the mixture was transferred into an autoclave for crystallization at elevated temperature (i.e.100 or 150℃).After filtrating,washing with deionized water and drying,zeolite products were obtained.The zeolite products were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),thermogravimetric analysis (TGA),and inductively coupled plasma emission spectrometer (ICP).KOH/SiO2 and H2O/SiO2 have significant influence on the phase transition behavior of zeolite Y.Highly crystalline zeolite MER can only be obtained with the optimized KOH/SiO2 and H2O/SiO2.With this method,the synthesis period of zeolite MER is greatly reduced,which might be applied to the synthesis of other industrially important zeolites in a shortened time.

Key words: zeolite, hydrothermal synthesis, phase transition, zeolite Y, zeolite MER