负载贵金属芳烃饱和催化剂抗硫性能研究 Ⅰ.载体酸性的影响

INVESTIGATION ON SULFUR RESISTIBILITY OF SUPPORTED NOBLE METAL CATALYSTS Ⅰ.Influence of Support Acidity

制备了不同酸性载体Ａｌ２Ｏ３，Ｆ－Ａｌ２Ｏ３，ＳｉＯ２－Ａｌ２Ｏ３及Ｙ分子筛负载的钯（Ｐｄ）催化剂。在压力４．２ＭＰａ，温度２６０～３００℃，重时空速４．０ｈ－１条件下用连续流动微反－色谱装置对催化剂进行了抗硫性能评价，模型反应物为甲苯－正己烷等体积混合液，含３０００μｇ／ｇ噻吩硫。用吡啶吸附红外光谱法研究了催化剂酸性；用ＣＯ原位吸附红外光谱法研究了活性金属Ｐｄ的电子性质。结果表明，随载体酸性增强，Ｐｄ原子缺电子性增强，加氢活性增加，催化剂抗硫性能提高；催化剂抗硫性能主要与载体表面的Ｂ酸有关，Ｌ酸与催化剂抗硫性能无关；在反应条件下，Ｐｄ／Ｙ的硫中毒具有可逆性。

Palladium catalysts supported on Al 2O 3,F Al 2O 3,amorphous SiO 2 Al 2O 3 and Zeolite Y have been prepared and characterized by using pyridine adsorbed and CO adsorbed infrared spectra.Resistance of these palladium catalysts to sulfur poisoning has been investigated by performing hydrogenation of toluene(containing 3000μg/g thiophene sulfur)with a fixed bed continuous flow microreactor under the conditions of 260～300℃,4 2MPa,WHSV 4 0h -1 .The existence of electron deficient Pd species was confirmed and correlated to acidity of catalysts and catalytic behavior.It was found that the stronger the acidity,the higher the electron deficiency,the better the sulfur resistance.Acidity characterization indicated that Brnsted acid sites of the catalysts favor the sulfur resistance and Lewis acid sites do not.It was also concluded that the adsorption of sulfur on catalyst Pd/Y is reversible.