锐钛矿型TiO_(2)负载Ni单原子用于催化丙烷脱氢  

Catalytic propane dehydrogenation by anatase supported Ni single-atom catalysts

作　　者：张倩 江训柱 苏杨[1] 赵阳 乔波涛[1] Qian Zhang;Xunzhu Jiang;Yang Su;Yang Zhao;Botao Qiao(CAS Key Laboratory of Science and Technology on Applied Catalysis,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian 116023,Liaoning,China;University of Chinese Academy of Sciences,Beijing 100049,China;Dalian Institute of Chemical Physics,Dalian National Laboratory for Clean Energy,Chinese Academy of Sciences,Dalian 116023,Liaoning,China)

机构地区：[1]中国科学院大连化学物理研究所,中国科学院应用催化科技重点实验室,辽宁大连116023 [2]中国科学院大学,北京100049 [3]中国科学院大连化学物理研究所,大连洁净能源国家实验室,辽宁大连116023

出　　处：《Chinese Journal of Catalysis》2024年第2期105-113,共9页催化学报（英文）

基　　金：国家重点研发计划(2021YFA1500503);国家自然科学基金项目(21961142006,21972135);国家自然科学基金单原子催化基础研究中心(22388102);中国科学院青年基础研究项目(YSBR-022).

摘　　要：丙烯市场需求日益增长,丙烷脱氢(PDH)被认为是最有前途的丙烯定向生产技术之一.作为PDH商业催化剂,贵金属Pt的高成本和CrO_(x)基催化剂的毒性使它们的发展受到限制.镍基催化剂因具有廉价、环保的特点,在多种催化反应的应用中引起了研究人员的广泛关注.然而,镍在高温烷烃脱氢反应中的应用较少,目前,保持反应中镍(II)物种的稳定存在仍然是镍基PDH催化剂的主要挑战.近来,单原子催化剂(SAC)在烷烃碳氢键活化过程中表现出优异的催化性能,具有较好的丙烯选择性和出色的稳定性.当镍以单个原子的形式分散在载体上时,它更有可能以带正电的状态存在,但金属单原子的稳定存在是具有挑战性的.本文以锐钛矿型的二氧化钛为载体,采用等体积浸渍法分别制备了0.05 wt%载量的单个原子分散的催化剂(Ni SAC,Ni_(1)/A-TiO_(2))和5 wt%载量的纳米颗粒(NP)催化剂(Ni_(NP)/A-TiO_(2)).结合球差电镜、原位漫反射傅里叶变换红外光谱和X射线吸收光谱等表征结果表明,Ni SAC催化剂主要含有单个Ni原子,以Ni(II)价态孤立地分散在载体上,而Ni_(NP)/A-TiO_(2)催化剂中的Ni物种主要以纳米粒子(1±0.2 nm)的形式存在.在580℃的PDH反应中,Ni_(1)/A-TiO_(2)催化剂表现出较好的本征活性和丙烯选择性,而且比相应的Ni NPs催化剂具有更好的抗积炭稳定性,在Ni_(1)/A-TiO_(2)上得到的丙烯产率约为1.96 molC_(3)H_(6)gNi^(-1)h^(-1),超过NiNP/A-TiO_(2)样品(0.03 molC_(3)H_(6)gNi^(-1)h^(-1))的65倍,Ni SAC催化剂的丙烯时空收率(STYC_(3)H_(6))约为0.2 kg h^(-1) kg_(cat)^(-1),与文献报道的大部分非贵金属催化剂STY值相当(0.02-0.3 kg h^(-1) kg_(cat)^(-1)).还原后的TiO_(2)载体因具有丰富的氧空位(OVs)和配位不饱和的Ti^(3+)表现出一定的活性,而Ni SAC得到了更高的丙烷转化率,但Ni单原子的引入并没有增加OVs和Ti^(3+)的浓度,Ni单原子催化剂的活化能低于纯载体,说明�With the increasing production of propane from shale gas and the growing demand for propylene,propane dehydrogenation(PDH)has gained significant attention as a promising route for the on-purpose production of propylene.As a cheap yet efficient catalyst,Ni-based catalysts have attracted interest because of its ability to activate alkane.Single-atom catalysts(SACs)can maximize the metal atom utilization.Here,we demonstrate that anatase TiO_(2)supported Ni SAC(Ni_(1)/A-TiO_(2))exhibits not only superior intrinsic activity and propylene selectivity but also much better stability than the corresponding Ni nanoparticle(NP)catalyst(Ni_(NP)/A-TiO_(2))in PDH reaction at 580℃.The rate of propylene production on Ni_(1)/A-TiO_(2)is about 1.96 molC_(3)H_(6)gNi^(-1)h^(-1),about 65 times higher than that of Ni_(NP)/A-TiO_(2)sample(0.03 molC_(3)H_(6)gNi^(-1)h^(-1)).In combination of high-angle annular dark-field scanning transmission electron microscopy,in-situ diffuse reflectance infrared Fourier transform spectra,in-situ X-ray photoelectron spectroscopy and X-ray absorption spectroscopy characterizations,we confirm that the Ni SAC mainly contains individual Ni atom singly dispersed on the support in positive Ni(II)valence state.In addition,as a result of strong metal-support interaction(SMSI)between Ni NP and TiO_(2)carrier under reduced conditions,the Ni NPs sites are encapsulated by TiOx overlayer(~2 nm thick)thus display poor reaction performance.

关 键 词：丙烷脱氢 单原子催化剂 原子利用率 丙烯选择性 稳定性 

分 类 号：O643.3[理学—物理化学] TQ221.212[理学—化学]