碱土和稀土金属化合物对H-ZSM-5沸石催化剂改性的反应性能

Reaction properties of H-ZSM-5 zeolite catalysts modified by alkali-earth and rare-earth metal compounds

用碱土(AE)金属化合物及稀土(RE)金属化合物,对H ZSM 5沸石催化剂进行了改性处理;以甲苯 甲醇烷基化反应为探针,考察了催化剂的活性、选择性及稳定性。用XRD和SEM检测了合成ZSM 5沸石的结构,用NH3 TPD方法测试了催化剂表面酸性质。结果表明:经改性后的催化剂表面酸中心数减少,酸强度下降,稳定性增加,对二甲苯选择性明显提高。

H-ZSM-5 zeolite catalysts is modified by alkali-earth and rare-earth metal compounds. Using toluene-methanol alkylation as probe, Its activity, selectivity, and stability are examined. XRD and SEM are used to determine the structure of the synthesized ZSM-5 zeolite. Surface acidity of the catalysts are examined by NH_3-TPD. It is found that the acid strength and number of acid sites in the modified catalysts decrease. Its stability increase and its selectivity for xylene increases obviously.