Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science,South-Central Minzu University,Wuhan 430074,China
Cubic Co3O4 nanoparticles were synthesized using a hydrothermal method. Subsequently, four catalysts, designated as 5%Co/TiN, 10%Co/TiN, 15%Co/TiN, and 20%Co/TiN, were prepared by ultrasonic dispersion using TiN as the support. A variety of characterization techniques, including scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), nitrogen adsorption-desorption, and inductively coupled plasma mass spectrometry (ICP-MS), were employed to analyze the structures and performances of the catalysts. The results of TEM and EDS mapping indicated that the size of the Co3O4 nanoparticles was uniform and did not undergo significant changes after ultrasonic treatment. Except for the 20%Co/TiN catalyst, which exhibited partial agglomeration, the Co3O4 nanoparticles were uniformly dispersed on the remaining three catalysts. XPS and H2-TPR analyses indicated a strong interaction between the cobalt species and TiN. The performance of Fischer-Tropsch synthesis demonstrated that the initial CO conversion, TOF, and CTY were all linearly correlated with the cobalt loading. The 20%Co/TiN catalyst showed the highest initial CO conversion rate of 29.7% among the series, but exhibited poor stability, with a continuous decline in CO conversion rate over time. The deactivation was mainly due to the relatively large loading of cobalt metal, which resulted in a relatively short distance between cobalt particles, making them prone to agglomeration.
利用XPS对催化剂进行了表征.图6(a)为催化剂的Co 2p的电子结合能谱图,可见5%Co/TiN、10%Co/TiN、15%Co/TiN、20%Co/TiN 4个催化剂的Co2p的电子结合能均比纯相Co3O4高.分峰拟合后所得Co2+/Co3+值分别为0.62、0.57、0.56和0.53,比纯相Co3O4的要大,说明催化剂中TiN具有一定的给电子能力,使部分Co3+转变为Co2+.而随着负载量的增加,4个催化剂的Co 2p的电子结合能依次向减小,钴物种与TiN载体间的相互作用在逐渐减弱[18].图6(b)列出了N 1s的电子结合能谱图,对于载体TiN,位于396.03、397.15和399.18 eV处的能谱峰分别归属于TiN载体表面被部分氧化为TiO x N y 的N、TiN中的N3-的结合能,以及TiO x N y 中N的卫星峰[19-20].4个催化剂中的TiO x N y 的N和TiN中N3-的电子结合能均比TiN中的大,表明钴物种与载体表面的N元素存在一定的相互作用.随着催化剂中钴负载量的增加,Co/Ti值(分别为0.12、0.19、0.34、0.38)逐渐增大,N3-/TiOxNy值(分别为1.93、1.80、1.74、1.71,TiN为2.03)逐渐变小,说明钴物种在TiN载体表面的数目增加,且因钴氧化物的增加,表面被氧化为TiO x N y 的物种增多.
ROSTRUP-NIELSENJ R. New aspects of syngas production and use[J]. Catalysis Today, 2000, 63(2/4): 159-164.
[2]
MAITLISP M, ZANOTTIV. The role of electrophilic species in the Fischer-Tropsch reaction[J]. Chemical Communications, 2009(13): 1619-1634.
[3]
KHODAKOVA Y, CHUW, FONGARLANDP. Advances in the development of novel cobalt Fischer-Tropsch catalysts for synthesis of long-chain hydrocarbons and clean fuels[J]. Chemical Reviews, 2007, 107(5): 1692-1744.
[4]
ZHANGR, WANGY, GASPARDP, et al. The oscillating Fischer-Tropsch reaction[J]. Science, 2023, 382(6666): 99-103.
[5]
IGLESIAE.Design, synthesis, and use of cobalt-based Fischer-Tropsch synthesis catalysts[J]. Applied Catalysis A: General, 1997, 161(1/2): 59-78.
[6]
RYTTERE, HOLMENA. Deactivation and regeneration of commercial type Fischer-Tropsch co-catalysts—A mini-review[J]. Catalysts, 2015, 5(2): 478-499.
[7]
TSAKOUMISN E, RØNNINGM, BORGØ, et al. Deactivation of cobalt based Fischer-Tropsch catalysts: A review[J]. Catalysis Today, 2010, 154(3/4): 162-182.
CHENX, DENGD, PANX, et al. N-doped graphene as an electron donor of iron catalysts for CO hydrogenation to light olefins[J]. Chemical Communications, 2015, 51(1): 217-220.
[11]
ZHAOQ, HANX, LIANGH, et al. Activating nitrogen-doped carbon nanosheets by KOH treatment to promote the Fischer-Tropsch synthesis performance[J]. Chemical Engineering Journal, 2023, 455: 140810.
[12]
QIZ, GAOF, ZHOUC, et al. Ruthenium nanoparticles anchored on nitrogen-doped carbon nanocages for Fischer-Tropsch synthesis[J]. Acta Chimica Sinica, 2022, 80(8): 1100.
[13]
ZHAOY, HUANGS, LIUC, et al. Enhancing the stability of a cobalt-based Fischer-Tropsch synthesis catalyst using g-C3N4-coated SBA-15 as support[J]. Journal of the Taiwan Institute of Chemical Engineers, 2024, 156: 105328.
[14]
XIONGH, MOYOM, MOTCHELAHOM A, et al. Fischer-Tropsch synthesis: Iron catalysts supported on N-doped carbon spheres prepared by chemical vapor deposition and hydrothermal approaches[J]. Journal of Catalysis, 2014, 311: 80-87.
PHAAHLAMOHLAKA TUMELON, KUMI DAVIDO, DLAMINI MBONGISENIW, et al. Effects of Co and Ru intimacy in Fischer-Tropsch catalysts using hollow carbon sphere supports: Assessment of the hydrogen spillover processes[J]. ACS Catalysis, 2017, 7(3): 1568-1578.
[17]
TIANT, ZHOUS, FUD, et al. Characterization and controlling factors of pores in the Lower Cambrian Niutitang shale of the Micangshan Tectonic Zone, SW China[J]. Arabian Journal of Geosciences, 2019, 12(7): 251.
[18]
PERRETN, ALEXANDERA M, HUNTERS M, et al. Synthesis, characterisation and hydrogenation performance of ternary nitride catalysts[J]. Applied Catalysis A: General, 2014, 488: 128-137.
[19]
JAEGERD, PATSCHEIDERJ. A complete and self-consistent evaluation of XPS spectra of TiN[J]. Journal of Electron Spectroscopy and Related Phenomena, 2012, 185(11): 523-534.
[20]
LUF H, CHENH Y. XPS analyses of TiN films on Cu substrates after annealing in the controlled atmosphere[J]. Thin Solid Films, 1999, 355: 374-379.
[21]
PANZ, PARVARIM, BUKURD B. Fischer-Tropsch synthesis on Co/Al2O3 catalyst: Effect of pretreatment procedure[J]. Topics in Catalysis, 2014, 57(6): 470-478.
[22]
KOOH M, LEEB S, PARKM J, et al. Fischer-Tropsch synthesis on cobalt/Al2O3-modified SiC catalysts: Effect of cobalt-alumina interactions[J]. Catalysis Science & Technology, 2014, 4(2): 343-351.
[23]
VISWANATHANB, GOPALAKRISHNANR. Effect of support and promoter in Fischer-Tropsch cobalt catalysts[J]. Journal of Catalysis, 1986, 99(2): 342-348.
[24]
ZHAOY, ZHANGY, CHENJ, et al. SBA-16-supported cobalt catalyst with high activity and stability for Fischer-Tropsch synthesis[J]. ChemCatChem, 2012, 4(2): 265-272.