纳米羟基磷灰石负载镍甲烷干重整催化剂的载体形貌效应

Morphology effect of nano-hydroxyapatite as support for loading Ni in methane dry reforming

  • 摘要: 本研究通过对羟基磷灰石(HAP)的形貌调控,得到表面Ca、O、P分布不同的纳米棒状、片状和线状的HAP载体,负载1.25%的活性组分镍后,得到Ni/HAP-R、Ni/HAP-S和Ni/HAP-W催化剂进行甲烷干重整性能研究。其中,Ni/HAP-R催化剂表现出最优的活性和抗积炭性能。利用XRD、氮吸附-脱附、FT-IR、XPS及CO2-TPD,对催化剂晶相结构、电子性质及表面酸碱性进行表征,证实棒状HAP具有最高的比表面积,有利于Ni的分散锚定,因此,活性最佳。且棒状HAP表面富Ca–O–P碱性位点,能够有效活化CO2,促进积炭消除。TPSR实验进一步证实Ni/HAP-R催化剂上甲烷的深度裂解生成积炭的过程受到抑制,且在CO2存在时能够迅速转化为CO和H2,因此,具有良好的抗积炭性能。该研究为高稳定负载型催化剂的设计合成提供了新的思路。

     

    Abstract: In this paper, hydroxyapatite (HAP) with nanorod, nanosheet and nanowire morphologies were synthesized with different surface Ca, O and P distributions. After loading 1.25% of nickel, Ni/HAP-R, Ni/HAP-S and Ni/HAP-W catalysts were obtained and applied for MDR. Among them, the Ni/HAP-R catalyst showed the best performance. The geometric structure, electronic properties and surface basicity of the catalyst were characterized by XRD, N2 sorption, FT-IR, XPS and CO2-TPD. It proved that HAP-R possessed the larges surface area, thus beneficial for Ni dispersion to obtain high MDR activity. Meanwhile, it was rich in Ca-O-P which could accelerate the CO2 activation for coke elimination. TPSR experiments further confirmed that the deep cracking of methane on Ni/HAP-R catalyst was inhibited. However, it could be accelerated in the presence of CO2 to produce CO and H2. In this case, Ni/HAP-R catalyst showed excellent anti-coking performance. This study provides inspiration for the design and synthesis of highly stable heterogeneous catalysts.

     

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