甘油辅助HZSM-5分子筛的制备及其甲烷无氧芳构化催化性能研究

以正硅酸乙酯(TEOS)为硅源,甘油为辅助剂,在水热条件下合成HZSM-5分子筛。考察甘油添加量、晶化时间对HZSM-5分子筛的晶粒尺寸、相对结晶度和酸性等性质及其甲烷无氧芳构化催化性能的影响。利用X射线衍射(XRD)、扫描电镜(SEM)、氨程序升温脱附(NH_3-TPD)等分析手段对不同条件合成的HZSM-5分子筛样品进行表征。结果表明,在添加一定量的甘油辅助剂的条件下,通过调控晶化时间,可以提升HZSM-5分子筛的相对结晶度,在一定程度上抑制无定型SiO_2的产生,增加其酸量。在甲烷无氧芳构化反应中,甘油辅助合成的HZSM-5分子筛催化剂表现出优良的催化性能,与未添加甘油合成的HZSM-5分子筛催化剂相比,甲烷转化率、苯选择性和芳烃选择性均有较大提高,且具有较强的稳定性与容炭能力。

Preparation of HZSM-5 zeolite assisted by glycerin and its catalytic performance for methane aromatization

HZSM-5 zeolite was synthesized under hydrothermal condition with TEOS as silicon source and glycerin as auxiliary agent. The effects of glycerol addition and crystallization time on the grain size, relative crystallinity and acidity of HZSM-5 molecular sieves and their catalytic performance for anaerobic aromatization of methane were investigated. XRD, SEM, NH₃-TPD and other analytical methods were used to characterize the HZSM-5 molecular sieve samples synthesized under different conditions. The results show that the relative crystallinity of HZSM-5 molecular sieve can be increased through adding certain amount of glycerol adjuvant and adjusting the crystallization time, meanwhile, the formation of amorphous SiO₂ can be suppressed and the acid content can be increased. The HZSM-5 prepared with glycerol assistance shows excellent catalytic performance in methane anaerobic aromatization. Compared with the HZSM-5 catalyst synthesized without the addition of glycerin, the methane conversion rate, benzene selectivity and aromatic selectivity are all greatly improved, and it has better stability and resistance to carbon deposition.