La添加对S_2O_8^(2-)/ZrO_2-Al_2O_3固体超强酸催化剂性能的影响

Effect of La Content on the Catalytic Activity of the Solid Superacid S_2O_8^(2-)/ZrO_2-Al_2O_3

柠檬酸三丁酯(TBC)是绿色环保无毒的增塑剂,其传统合成工艺采用浓硫酸作催化剂,设备腐蚀、三废问题严重,开发高效、绿色的替代催化剂是当前研究的重点。本文采用共沉淀-浸渍法向S2O82-/ZrO2-Al2O3催化剂中引入适量的La元素,制备出具有较高催化活性和稳定性的固体超强酸催化剂;以柠檬酸三丁酯的合成为探针反应评价催化剂的活性,并通过红外光谱、X射线衍射、NH3程序升温脱附,吡啶红外光谱等表征方法考察了La的添加对催化剂结构和性能的影响,结果表明:La的加入能够阻止催化剂中过硫酸根的分解,增强S和O之间的相互作用;少量的La不仅能增加催化剂的比表面积、酸强度和酸量,且能提高催化剂的活性和稳定性,当La的加载量为1%时,制得的催化剂活性最高,柠檬酸的转化率达到93.69%。这表明La的引入可提高固体超强酸催化剂的活性和稳定性,所制备的催化剂可用于传统催化剂浓硫酸的替代品,并有效降低设备的损耗,提高产品TBC的品质,优化TBC合成工艺,具有良好的经济价值。

Tri-n-butyl citrate（TBC） as a green environmentally friendly and non-toxic plasticizer, and traditional synthesis process use the sulfuric acid as catalyst that corrosiveness to reactors and containers,and the serious problem of three wastes.Exploit of effective and green catalyst is the current research focus.In this work,highly active and stable solid superacid catalyst was prepared by simultaneously introducing appropriate amounts of La into a S2O8^2-/ZrO2-Al2O3 catalyst by precipitation and impregnation method.The catalytic performance for the synthesis of Tri-n-butyl citrate was investigated.The synthesized catalysts were fully characterized by means of FT-IR,XRD,NH3-TPD and FT-IR of adsorbed pyridine analysis methods.The experiments results show that the introduction of lanthanum inhibits the decomposition of sulfuric and strengthen the combination between S and O.A small number of La not only can increase the surface area and acid strength and the amount of acid sites of catalysts,but also can enhance the activity of catalyst.The catalyst loaded with 1wt% lanthanum samples exhibited higher activity for synthesis of Tri-n-butyl citrate and the conversion rate could reach 93.69%.This suggests that the addition of La improved activity and stability of solid superacid catalyst,and the resultant catalyst can be used to substitute for traditional sulfuric acid catalyst,which effectively reduce the wear and tear of equipment,improve the quality of the product TBC and optimize TBC synthesis process.In summary,the catalyst has the good economic value.