异辛烷蒸汽重整制氢的研究——Ⅰ．抗硫中毒的Pt/CeO_2/Al_2O_3催化剂的制备及其反应性能

Steam Reforming of iso-Octane for Hydrogen Production——Ⅰ.Preparation and Catalytic Performance of Sulfur-Tolerant Catalyst Pt/CeO_2/Al_2O_3

用初湿浸渍法制备了Pt/CeO_2/Al_2O_3催化剂,在异辛烷中加入噻吩硫(硫含量300μg/g),考察了反应条件和催化剂制备条件对异辛烷蒸汽重整反应的影响。实验结果表明,优化的反应条件为:反应温度800℃、水与原料中碳的摩尔比5.3、异辛烷的重时空速1.0h^(-1);优化的催化剂制备条件为:在γ-Al_2O_3上先负载CeO_2并于450℃焙烧,然后再负载Pt并于600℃焙烧,其中CeO_2和Pt的负载量(质量分数)分别为15%和0.8%。在优化制备条件下制得的Pt/CeO_2/Al_2O_3催化剂对异辛烷蒸汽重整反应具有很好的抗硫中毒性能、活性和稳定性。该催化剂在优化反应条件下进行了100h实验,异辛烷转化率在反应前40h接近100.0%,之后略有下降并稳定在95.0%以上,产物中H_2的摩尔分数约为75.0%、CH_4的摩尔分数约为1.0%。

High sulfur-tolerant Pt/CeO2/Al2O3 catalyst had been prepared by incipient wetness impregnation. Effects of reaction and catalyst preparation conditions on performance of Pt/CeO2/ Al2O3 catalyst for steam reforming of iso-octane with 300μg/g thiophene sulfur in feed were investigated. The optimal reaction conditions are reaction temperature of 800℃, mole ratio of steam to carbon of 5.3 and iso-octane WHSV of 1.0 h^-1. The optimal CeO2 and Pt mass fraction in catalyst are 15% and 0. 8%, respectively. The optimal preparation procedures and conditions of Pt/CeO2/Al2O3 catalyst are： γ-Al2O3 support were incipiently impregnated with Ce（ NO3 ）3 · 6H2O aqueous solution, followed by calcination at 450 ℃, and then re-impregnated with H2PtCl6· 6H2O aqueous solution, followed by calcination at 600℃. The resulted catalyst was tested for 100 h run, which possesses excellent sulfur tolerance, high catalytic activity and good stability, iso-Octane conversion is almost 100. 0% within 40 h and then slowly decreases to 95.0%, while H2 mole fraction in product stream remains at 75.0% with CH4 mole fraction about 1.0%.