镝对固体超强酸催化剂ZrO_2-Dy_2O_3/SO_4^(2-)-HZSM-5的酸性和稳定性的影响

Effect of Dysprosium on Acidity and Stability of Solid Superacid ZrO_2 Dy_2O_3/SO_4^(2-) HZSM-5 Catalyst

合成了固体超强酸催化剂 Zr O2 - Dy2 O3/ SO42 - ,并将其负载于分子筛 HZSM- 5上 ,制成复合型固体超强酸催化剂 Zr O2 - Dy2 O3/ SO42 - - HZSM- 5 (以下简称催化剂 ZDSH) .采用 Hammett指示剂法、吸附吡啶的 TPD法 ,考察催化剂 ZDSH的酸强度及其分布 ;通过热重分析 (TGA)、差热分析 (DTA)方法 ,考察镝对催化剂 ZDSH稳定性的作用 ;运用红外光谱 (IR)法 ,分析催化剂 ZDSH表面 SO42 -的结构 .结果表明 ,催化剂 ZDSH能催化柠檬酸与正丁醇的酯化反应 ,转化率达 97.6 7% ,反复使用 5次后 ,转化率仅下降 4.41% ;镝对催化剂 ZDSH的酸强度和酸量具有较大的调变作用 ,且能降低催化剂表面的积炭量 ,并且能通过形成镶嵌式结构抑制 SO42 -的流失 ,显著提高催化剂 ZDSH的稳定性 .

A new complex solid superacid ZrO 2 Dy 2O 3/SO 4 2- HZSM 5(ZDSH) catalyst was prepared by preparing solid superacid ZrO 2 Dy 2O 3/SO 4 2- and loading it on HZSM 5 zeolite. The surface acid strength and its distribution were characterized by Hammett indicator and Py TPD. The effects of Dy on stability were investigated using TGA and DTA, and the structure of SO 4 2- on the catalyst surface was studied using IR. The results show that ZDSH catalyst increases the conversion of citric acid in esterification with n butanol to 97.67%, which only decreases by 4.41% after 5 runs. Since Dy can not only adjust the acid strength distribution, but also decrease the carbon deposition of the catalyst and restrain the loss of SO 4 2- by forming mosaic structure, the stability of the catalyst can be improved effectively.