Abstract

Ni catalysts with different loadings (10, 15 and 20 wt%) supported on MgAl₂O₄ were studied for Liquefied Petroleum Gas (LPG) steam reforming. In-situ X-ray diffraction (XRD) and XANES (X-ray absorption near-edge structure), analyses showed that the initial reduction temperature was related to the percentage of Ni present in the catalyst. Extended X-ray absorption fine structure (EXAFS) data indicated similar Ni-Ni interatomic distances for all the samples and very close to the simulated value found for reference of Ni⁰, indicating the complete reduction of the samples. MgAl₂O₄ supported Ni catalysts were active for LPG steam reforming at 873 K, with some deactivation after 24 h of reaction. The samples with higher Ni loadings (20Ni/MgAl₂O₄ and 15Ni/MgAl₂O₄) showed similar LPG steam reforming products, with H₂ representing around 78% of the products detected in the gas phase (dry molar basis). 10Ni/MgAl₂O₄ was less active, although it also presented high H₂ formation. Thermogravimetric analysis showed that carbon deposition was a significant factor for catalyst deactivation.

摘要

研究了负载在MgAl ₂ O ₄上的负载量分别为10、15和20 wt％的Ni催化剂用于液化石油气（LPG）蒸汽重整。原位X射线衍射（XRD）和XANES（X射线吸收近边缘结构）分析表明，初始还原温度与催化剂中Ni的百分比有关。扩展的X射线吸收精细结构（EXAFS）数据表明，所有样品的Ni-Ni原子间距离相似，并且非常接近为Ni ⁰参考所获得的模拟值，表明样品完全还原。镁₂ O ₄负载的Ni催化剂对873 K的LPG蒸汽重整具有活性，反应24 h后会失活。Ni含量较高的样品（20Ni / MgAl ₂ O ₄和15Ni / MgAl ₂ O ₄）显示出相似的LPG蒸汽重整产物，其中H ₂占气相中检测到的产物的78％（以干摩尔计）。10Ni / MgAl ₂ O _4的活性较低，尽管它也具有较高的H ₂形成率。热重分析表明，碳沉积是催化剂失活的重要因素。