过渡金属调节酸性位点促进钯催化剂C-H键裂解能力提高甲烷完全燃烧性能  

Regulating acid sites by transition metals to promote C-H bond cracking ability of Pd catalysts for methane complete combustion performance improvement

作　　者：夏良辉 王晶晶 建艳飞 刘昱洁 何炽[1,2] XIA Lianghui;WANG Jingjing;JIAN Yanfei;LIU Yujie;HE Chi(State Key Laboratory of Multiphase Flow in Power Engineering,School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China;National Engineering Laboratory for VOCs Pollution Control Material&Technology,Beijing 101408,China)

机构地区：[1]西安交通大学能源与动力工程学院动力工程多相流国家重点实验室,陕西西安710049 [2]挥发性有机物污染控制材料与技术国家工程实验室,北京101408

出　　处：《热力发电》2024年第7期135-142,共8页Thermal Power Generation

基　　金：国家重点研发计划(2022YFB4101500);国家自然科学基金项目(22276145,21922606)。

摘　　要：甲烷作为主要大气污染物之一,因其具有稳定的四面体分子结构,给其在温和条件下的催化氧化消除带来巨大挑战。旨在通过引入过渡金属(Cr、Mo、W)改性Pd基催化剂的酸性位点,促进C-H键的裂解,以增强甲烷催化氧化性能。通过XRD、Raman、H2-TPR、NH3-TPD等多种表征手段对催化剂的氧空位、酸性及氧化还原性能进行了系统探究。结果表明:过渡金属改性使得Pd催化剂的酸性位点显著增加,且过渡金属改性的PdM催化剂具有更高的氧空位数量;Mo改性的PdMo催化剂表现出更优异的氧化还原性能,而Cr和W改性的PdCr及PdW催化剂的氧化还原性能稍有下降;甲烷氧化反应结果表明,酸性位点适中的PdMo催化剂具有最优异的甲烷氧化性能,其T90温度较Pd催化剂降低约150℃,且表现出更好的反应稳定性;然而,酸性位点数量较多或较少的PdCr及PdW催化剂表现出较低的甲烷氧化活性,说明催化剂的酸性位点数量和氧化还原性能共同决定了其甲烷氧化性能。该结论为设计制备用于甲烷完全氧化的低温高效催化剂提供了思路。Methane is one of the main components of atmospheric pollutants,which is challenging to be eliminated by catalytic oxidation under mild conditions because of its tetrahedral structure stability.In this work,the acidic sites of Pd-based catalysts are modified by introducing transition metals(Cr,Mo,W)to promote the cleavage of C-H bonds and therefore to enhance the catalytic oxidation performance of methane.The oxygen vacancies,acidity and redox property of prepared catalysts are systematically characterized by XRD,Raman,H2-TPR and NH3-TPD techniques.The results show that,the transition metal modification increases the acidic site of Pd catalysts obviously,and the modified PdM catalysts have a higher amount of oxygen vacancies.However,only Mo modified PdMo catalyst exhibits better redox performance,while Cr and W modified PdCr and PdW catalysts show slightly lower redox performance.The results of the methane oxidation reaction confirm that the PdMo catalyst with moderate acidic sites displays excellent performance in the methane oxidation reaction,and its T90 decreases by about 150℃,while the PdCr and PdW catalysts with more and less acidic sites show lower methane oxidation activity.The results indicate that the number of acid sites and the redox properties of the catalyst jointly determine the methane oxidation performance.This conclusion provides critical insights for design and preparation of catalysts for complete oxidation of methane at low temperatures.

关 键 词：甲烷 钯催化剂 过渡金属 酸性位点 氧化还原性能 

分 类 号：O643.36[理学—物理化学]