超声化学共沉淀法制备SO4^2-/ZrO2/Al2O3固体酸及其催化作用

采用超声化学共沉淀法制备SO4^2-/ZrO2/Al2O3固体超强酸催化剂，采用FT-IR、TG-DTG对催化剂进行了表征，并对催化剂的酸性强度及催化乙二胺合成哌嗪的性能进行了研究．结果表明，该催化剂具有桥式双配位结构，该结构在温度超过700℃时被破坏；随浸渍溶液浓度增大，催化剂的酸性强度和含硫量均先增大后减小；随陈化时间增加，催化剂的酸性强度增大，但陈化时间超过9h后，催化剂的酸性强度没有明显变化；焙烧温度不超过550℃时，催化剂的酸性强度随焙烧温度升高而增强，但温度超过550℃后，催化剂的酸性强度随焙烧温度升高反而降低；随催化剂中Al摩尔分数的增大，催化剂的酸性强度先增大后减小．引入Al对于提高乙二胺的转化率、改善哌嗪的收率和选择性具有一定的作用，并且哌嗪的收率和选择性随Al含量的增大而增大．

Synthesis and catalytic property of SO4^2-/ZrO2/Al2O3 solid superacid by co-precipitation under ultrasonic irradiation

In this paper, SO4^2-/ZrO2/Al2O3 solid superacid catalyst was synthesized by co-precipitation method under ultrasonic irradiation and characterized with FT-IR and TG-DTG, influence of technical conditions on acidity was investigated, catalytic property on piperazine synthesizing were investigated as well. The results showed that the structure of the catalyst was double binding of SO4^2- on the metal ion, the acidity of SO4^2-/ZrO2/Al2O3 solid superacid catalyst increased with＇ increasing of （ NH4 ） 2SO4 solution if the concentration was less than 1 2tool/L, and the acidity of SO4^2-/ZrO2/Al2O3 solid superacid catalyst increased with increasing of roasting temperature and Al content. The acidity was improved after irradiation of ultrasonic. When SO4^2-/ZrO2/Al2O3 solid superacid was used as catalyst for synthesis of piperazine, the conversion rate of ethylenediamine increased with creasing of feeding rate and concentration of ethylenediamine, increased with decreasing of reaction temperature and feeding increasing of reaction temperature and dewhile the yield and selectivity of piperazine rate and concentration of ethylenediamine. With increasing of Al content in the catalyst, the conversion rate of ethylenediamine and the yield and selectivity of piperazine increased.