堇青石表面涂层对Pd基整体式催化剂结构和性能的影响

Influences of Coat on Cordierite Surface on Structure and Performance of Pd-Based Monolithic Catalysts

分别以硫酸铝、拟薄水铝石、氯化铝、硝酸铝为铝源制备铝溶胶,并将铝溶胶涂覆于堇青石表面,制备了γ-Al2O3/堇青石载体;将PdCl2溶液浸渍于γ-Al2O3/堇青石载体上,制得Pd/γ-Al2O3/堇青石催化剂。采用XRD,SEM,XPS,BET等手段对催化剂进行表征,并对催化剂的甲烷催化燃烧活性进行评价。实验结果表明,不同铝源制备的催化剂的比表面积按硫酸铝>拟薄水铝石>氯化铝>硝酸铝的顺序依次减小;硫酸铝、拟薄水铝石、氯化铝为铝源的催化剂中Pd以PdO和金属Pd的形式存在,硝酸铝为铝源的催化剂中除了PdO也可能存在Pd(OH)2;硫酸铝为铝源的催化剂活性最高,在反应温度485.6℃下,甲烷转化率可达90%;不同铝源制备的催化剂活性高低顺序为:硫酸铝>拟薄水铝石>氯化铝>硝酸铝。

Pd/γ-Al2O3/cordierite catalysts were prepared by the impregnation of γ-Al2O3/cordierite supports in PdCl2 solution.The supports were prepared by coating alumina sols,which were prepared from different aluminum sources（aluminum sulfate,aluminum nitrate,aluminum chloride and pseudo-boehmite）,on cordierites.The catalysts were characterized by means of XRD,SEM,XPS and BET,and their activities in the catalytic combustion of methane were evaluated.The results indicated that the catalysts from different aluminum sources had different pore structures,and their specific surface areas decreased in order of：aluminum sulfate＞pseudo-boehmite＞aluminum chloride＞aluminum nitrate.In the catalyst with aluminum nitrate as aluminum source,Pd existed in the form of PdO and Pd（OH）2,whereas in the other catalysts,Pd existed in the form of PdO and Pd.The catalytic activity of the catalyst with aluminum sulfate as aluminum source was the highest with the methane conversion of 90％ at 485.6 ℃.The catalytic activities of all the catalysts were arranged in order of：aluminum sulfate＞pseudo-boehmite＞aluminum chloride＞aluminum nitrate.