Ce_(0.8)Gd_(0.2)O_(1.9)制备方法对负载的铂催化剂在异辛烷水蒸气重整制氢过程中抗硫中毒性能的影响

Effect of Preparation Method of Ce_(0.8)Gd_(0.2)O_(1.9) Supports on Sulfur Tolerance of Supported-Platinum Catalysts for Steam Reforming of Iso-Octane

以柠檬酸溶胶-凝胶法、六亚甲基四胺共沉淀法和草酸共沉淀法合成了具有萤石结构的Ce0.8Gd0.2O1.9（CGO）复合氧化物,并用初湿浸润法制备了负载型Pt/CGO催化剂。纯异辛烷的重整反应结果显示,制得的催化剂均达到了热力学平衡转化。抗硫测试表明,用柠檬酸溶胶-凝胶法所制载体制备的催化剂具有最好的抗硫中毒性能,在300μg·g^-1硫存在条件下,100 h内异辛烷均接近完全转化。用六亚甲基四胺共沉淀法和草酸共沉淀法所制载体制备的催化剂,在相同硫含量条件下,100 h后异辛烷的转化率分别降至-90%和-82%。这主要是由于二者热稳定性较差和Pt与CGO复合氧化物载体之间相互作用较弱所致。催化剂储氧量与其抗硫中毒性能并无直接关联。另外,3种催化剂均具有良好的抗积炭性能。

The fluorite-type Ce0.8Gd0.2O1.9 （CGO） oxide supports were synthesized by citric acid sol-gel, hexamethylenetetramine coprecipitation and oxalic acid coprecipitation, respectively. The Pt/CGO catalysts were prepared by highly dispersing Pt onto the pore surfaces of the as-made CGO supports using incipient wetness impregnation. Sulfur tolerance of the catalysts was tested in steam reforming of iso-octane at 750℃ and a WHSV （iso-octaue） of 1.0 h^-1 with a stcam/C molar ratio of 3, with thiophene as sulfur source. It was found that the preparation method of CGO oxide supports influenced sulfur tolerance of the catalysts. The catalyst which using the support that was synthesized by citric acid sol-gel method exhibited the best sulfur tolerance. This catalyst maintained its activity and selectivity in the entire 100 h test with 300 μg·g^-1 sulfur. In contrast, the catalysts which using the supports that were synthesized by oxalic acid coprecipitation and hexamethylenetetramine coprecipitation, both lost their activity slowly to - 90% and - 82%, because of their poorer thermal stability and weaker interaction between Pt and CGO oxide at their interface. It was also found that the sulfur tolerance of the catalysts was not correlated with their oxygen storage capacity （OSC）. In addition, three catalysts all showed good resistance to carbon deposition in the steam reforming of iso-octane with 300μg·g^-1 sulfur.