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采用季铵盐表面活性剂辅助模板法合成了一系列多级孔Hβ(H-Hβ)分子筛,通过XRD、XRF、SEM、TEM、N_2吸附-脱附、NH_3-TPD等表征方法对合成的H-Hβ分子筛物化性质进行分析,并在固定床反应器上对其催化苯胺缩合制二苯胺的性能进行了评价。结果表明,通过加入季铵盐表面活性剂,在合成的Hβ分子筛中成功引入了介孔,形成了微孔-介孔的复合孔道结构,增大了Hβ分子筛的孔容和孔径,有利于大分子的扩散。季铵盐表面活性剂碳链长度越长,合成的H-Hβ分子筛介孔孔容和孔径越大。相较于常规的Hβ分子筛(苯胺转化率为18.5%),H-Hβ分子筛可以显著提高苯胺转化率至31.0%~33.23%,二苯胺选择性都超过96%。另外,以十六烷基三甲基溴化铵为辅助试剂合成的H-Hβ分子筛随着硅铝比的减小,其酸量逐渐增多,苯胺转化率也逐渐提高,而选择性基本保持不变。
A series of multi-level pore Hβ (H-Hβ) molecular sieves were synthesized by the quaternary ammonium surfactant-assisted template method and characterized by XRD, XRF, SEM, TEM, N_2 adsorption-desorption and NH_3- -Hβ molecular sieve was analyzed, and its performance in the aniline condensation of diphenylamine was evaluated in a fixed-bed reactor. The results showed that mesopores were successfully introduced into the synthesized Hβ zeolite by adding quaternary ammonium surfactants, forming microporous-mesoporous composite pore structure and increasing pore volume and pore size of Hβ zeolite, The proliferation of molecules. The longer the carbon chain length of the quaternary ammonium surfactant, the larger the mesopore volume and pore size of the synthesized H-Hβ molecular sieves. Compared with the conventional Hβ molecular sieve (aniline conversion of 18.5%), H-Hβ molecular sieve can significantly improve the conversion of aniline to 31.0% ~ 33.23%, diphenylamine selectivity of more than 96%. In addition, with the cetyltrimethylammonium bromide as an auxiliary reagent synthesis of H-Hβ molecular sieve with the Si-Al ratio decreased, the amount of its acid gradually increased, aniline conversion rate also gradually increased, while the selectivity remained essentially change.