蛋壳型Pt/α-Al_2O_3催化剂催化6-氯-3-硝基甲苯-4-磺酸液相连续加氢合成CLT酸的研究

Synthesizing CLT Acid from Liquid-phase Catalytic Hydrogenation of 6-chloro-3-nitrotoluene-4-sulfonic Acid with Eggshell-shaped Pt/α-Al_2O_3 Catalyst

以稳定态晶型α-Al2O3为载体,采用浸渍法制备了低负载量蛋壳型Pt/α-Al2O3催化剂,使用涓流床反应器,将该催化剂应用于6-氯-3-硝基甲苯-4-磺酸液相催化加氢合成CLT酸的反应,考察了Pt的负载量、催化剂的还原方式、催化剂的焙烧温度等对6-氯-3-硝基甲苯-4-磺酸液相催化加氢合成CLT酸的影响.实验结果表明:Pt负载量的质量分数为0.15%,催化剂焙烧温度为400℃,氢气还原300℃×2 h时,6-氯-3-硝基甲苯-4-磺酸的转化率高达97%,并且有效抑制了脱氯反应的发生.此外,XRD、TEM和EDS表征结果表明:活性组分Pt以纳米颗粒形式存在,尺寸极小且在α-Al2O3载体上高度分散,这有利于6-氯-3-硝基甲苯-4-磺酸液相催化加氢合成CLT酸.

Eggshell-shaped Pt/α-Al2O3 catalysts are prepared using the impregnation method over thermally stable α-Al2O3 supports and applied in liquid phase catalytic hydrogenation of 6-chloro-3-nitrotoluene-4sulfonic acid to produce CLT acid in a trickle-bed reactor.The effects of loading of active components in catalysts,reduction method of catalysts and calcination temperature of catalysts on the catalytic performance are investigated.97% 6-chloro-3-nitrotoluene-4-sulfonic acid conversion is reached with eggshell-shaped 0.15% Pt/α-Al2O3catalysts calcined at 400 ℃,followed by reducing with H2at 300 ℃ for 2 h.The catalyst shows high selectivity for formation of CLT acid,and inhibits the de-chlorination reaction effectively.XRD,TEM and EDS results confirm that the Pt particles are mono-dispersed with spherical shape over the α-Al2O3 support,which is beneficial to the catalytic hydrogenation.