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首页> 外文期刊>ACS catalysis >Methane Combustion over Pd/Al2O3 Catalysts in the Presence of Water: Effects of Pd Particle Size and Alumina Crystalline Phase
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Methane Combustion over Pd/Al2O3 Catalysts in the Presence of Water: Effects of Pd Particle Size and Alumina Crystalline Phase

机译：在水存在下Pd / Al2O3催化剂的甲烷燃烧：Pd粒径和氧化铝结晶相的影响

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摘要

The effects of the Pd particle size and the Al2O3 crystalline phase of Pd/Al(2)O(3 )catalysts on the CH4 combustion in the presence of H2O were investigated. According to X-ray absorption fine structure (XAFS) measurements, it was revealed that, during the CH4 combustion, the Pd nanoparticles existed on the Al2O3 support as a PdO phase, while the crystallinity of PdO depended on the Pd particle size. On the basis of X-ray diffraction XRD), amorphous PdO particles with a size of <7 nm exhibited low activity for CH4 combustion. In contrast, as the Pd particle size increased, larger crystalline PdO particles (>7 nm) were formed, which were highly active for CH4 combustion. Comparing the effects of the different Al(2)O(3 )crystalline phases, Pd/alpha-Al2O3 was proved to be more resistant to deactivation by H2O than Pd/gamma-Al(2)O(3 )and Pd/theta-Al2O3. Moreover, according to H2O temperature-programmed desorption (TPD) and infrared (IR) measurements, since alpha-Al2O3 was relatively hydrophobic compared to gamma-Al2O3 and theta-Al2O3, a faster and reversible adsorption/desorption of OH/H2O species was achieved, while the H2O poisoning on PdO species in the vicinity was limited.
机译：研究了Pd / Al（2）o（3）催化剂在H2O存在下在CH4燃烧中的Pd / Al（2）O（3）催化剂的效果。根据X射线吸收细结构（XAFS）测量，揭示了在CH4燃烧期间，在Al 2 O 3载体上存在Pd纳米粒子作为PDO相，而PDO的结晶度依赖于Pd粒径。在X射线衍射XRD的基础上，具有尺寸<7nm的无定形PDO颗粒表现出低活性的CH 4燃烧。相反，随着Pd粒径增加，形成较大的结晶PDO颗粒（> 7nm），其对CH 4燃烧非常有效。比较不同Al（2）O（3）结晶相的效果，证明Pd /α-Al 2O3的耐抗性比Pd /γ-Al（2）o（3）和Pd /θ - Al2O3。此外，根据H2O温度编程的解吸（TPD）和红外（IR）测量，由于与γ-Al2O3和θ-Al2O3相比，α-Al2O3相对疏水，因此实现了OH / H2O物种的更快和可逆的吸附/解吸，而H2O中毒在附近的PDO物种是有限的。

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