Highly-efficient hydroxyapatite-supported nickel catalysts for dry reforming of methane
Highly-efficient hydroxyapatite-supported nickel catalysts for dry reforming of methane
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DOI：
10.1016/j.ijhydene.2019.08.068
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发表时间：
2020-07
影响因子：
7.2
通讯作者：
Bruna Rego de Vasconcelos;Doan Pham Minh;E. Martins;A. Germeau;P. Sharrock;A. Nzihou
中科院分区：
文献类型：
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作者：
Bruna Rego de Vasconcelos;Doan Pham Minh;E. Martins;A. Germeau;P. Sharrock;A. Nzihou
用两种不同物理化学性质的羟基磷灰石(Ca-HA1，Sbet=10.7×m~2/g和Ca-HA2，Sbet=0.60×m~2/g)制备了镍基催化剂。本研究的目的是评价这两种材料作为干法重整反应(DRM)载体的性能，并考察不同的工艺参数，如温度、压力、时间和催化剂预处理等对这两种催化剂性能的影响。进行了热力学计算，以确定限制固体碳沉积和有利于反应物转化的条件。然后，通过实验参数研究考察了温度、压力、催化剂前处理和载体热处理对催化剂性能的影响。结果表明，与未处理的催化剂相比，经催化剂预处理后的催化剂对镍的还原程度更高，具有更好的催化性能。需要700摄氏度左右的高温和1.6摄氏度左右的低压，才能实现约70-80%的高CH4和CO2转化率以及约90%的高H_2和CO选择性。在所有情况下，Ni/Ca-HA2催化剂表现出比Ni/Ca-HA1更好的催化性能，这是因为存在更小的镍颗粒(10-20 nm)，更强的碱性，更高的碱性中心密度(0.23mmolg−1)和更高的比表面积(Sbet=0.60mmo2/g)。Ni/Ca-HA2催化剂具有较高的催化活性(初始甲烷转化率为75%)，在TOS反应90h内相对稳定，其催化性能与文献报道的以常规载体制备的镍基催化剂相当。
Ni-based catalysts were prepared using two hydroxyapatites (Ca-HA1, SBET= 7 m2/g and Ca-HA2, SBET= 60 m2/g) with different physico-chemical properties. The objective of the study was to evaluate the performance of these two materials as promising supports for dry reforming reaction (DRM) as well as to investigate the influence of different process parameters, such as temperature, pressure, time and catalyst pretreatment on the performance of these two catalysts. Thermodynamic calculations were performed to determine the conditions that would limit solid carbon deposit and favor the reactants conversion. Then, an experimental parametric study was carried out to investigate the impact of the temperature, pressure, catalyst pretreatment and support thermal treatment on the catalysts performance. The results showed that the catalyst pretreatment allowed the reduction of the nickel particles in a higher extent, which resulted in better catalytic performance when compared to the catalysts without pretreatment. High temperatures around 700 °C and low pressures around 1.6 bar were required to attain high CH4and CO2conversions around 70–80% as well as high H2and CO selectivity around 90% for 90 h of time on stream. In all cases, Ni/Ca-HA2 catalyst presented better catalytic performance than Ni/Ca-HA1 due to the presence of smaller nickel particles (10–20 nm), stronger basicity, higher density of basic sites (0.23 mmol g−1) as well as higher specific surface area (SBET= 60 m2/g) of the Ca-HA2 support. Ni/Ca-HA2 catalyst was highly active (initial methane conversion: 75%) and relatively stable during 90 h of TOS and its catalytic behavior was comparable with the performance of Ni-based catalysts prepared with conventional supports reported in the literature.