Direct Synthesis and Characteristics of NH4-beta Zeolite with Hierarchical Pore Structure

作者：Chen Ran; Gong Yan Jun; Li Qiang; Dou Tao^*; Zhao Zhen; Xu Qing Hu

来源：Acta Physico - Chimica Sinica, 2009, 25(3): 539-544.

• NH4-beta zeolite
• Hierarchical porous structure
• C-4 alkane mixture
• Catalytic cracking
• Fluoride mineralizer

NH4-beta zeolite with hierarchical porous structure was directly prepared in a nearly neutral synthetic system using nonionic compound (polyoxyethylene nonyl phenylether) as the mesoporogen and fluoride as a mineralizer. Samples were characterized by powder X-ray diffractometry (PXRD), scanning electron microscopy (SEM), NH3-temprature programmed desorption (NH3-TPD), N-2 adsorption/desorption and differential thermogravimetry (DTG). N-2 analysis results showed that the synthesized H-(NH4)-beta zeolite contained stepwise distributed micro-mesoporous structure. The Barrett-Joyner-Halenda (BJH) method of analyzing the N-2 adsorption isotherm showed that the mesopore volume was 0.67 cm(3).g(-1) and the most probable pore size was about 21.8 nm. This value was higher than that for the conventional H-beta zeolite (0.37 cm(3).g(-1) and 3.8 nm). The large amount of Lewis acid and the moderate amount of Bronsted acid in the H-(NH4)-beta zeolite was examined by means of Pyridine-IR spectroscopy. Compared to conventional H-beta zeolite, the conversion in the catalytic cracking reaction of mixed C, hydrocarbons using this H-(NH4)-beta zeolite was improved by 15%. Yields for the olefins (ethene and propene) and aromatic hydrocarbons (benzene and toluene) increased by 10% and 3%, respectively.

• 出版日期2009-3
• 单位中国石油大学（北京）