In situ magnetometer study on the formation and stability of cobalt carbide in Fischer-Tropsch synthesis

被引:136
作者
Claeys, M. [1 ]
Dry, M. E. [1 ]
van Steen, E. [1 ]
du Plessis, E. [2 ]
van Berge, P. J. [2 ]
Saib, A. M. [2 ]
Moodley, D. J. [2 ]
机构
[1] Univ Cape Town, Dept Chem Engn, Ctr Catalysis Res, ZA-7701 Rondebosch, South Africa
[2] Sasol Technol R&D, ZA-1947 Sasolburg, South Africa
关键词
Cobalt carbide; Fischer-Tropsch synthesis; In situ magnetic measurements; XRD; CO HYDROGENATION; CATALYSTS; SURFACE; CARBON; DEACTIVATION; TRANSITION; IRON; DIFFUSION; DFT;
D O I
10.1016/j.jcat.2014.08.002
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
While carbides are always present in iron-based Fischer-Tropsch synthesis, very little is known about the presence and the role of carbides in cobalt-based CO hydrogenation. Cobalt carbide, CO2C, has been reported in catalysts where operational upsets occurred and it is associated with low catalyst activity and increased methane selectivity. In this study, a novel in situ magnetometer was used to study the formation and the stability of cobalt carbide during the Fischer-Tropsch synthesis at fully relevant conditions. The formation of cobalt carbide was confirmed by means of in situ XRD and synchrotron XRD measurements. Cobalt carbide is relatively stable at typical reaction conditions, but a rapid decomposition into hcp cobalt occurs in hydrogen above 150 degrees C. Cobalt carbide formation is inversely proportional to the H-2/CO ratio and the reaction temperature. However, the amounts of cobalt carbide formed are small and the impact on deactivation at realistic Fischer-Tropsch conditions should generally be negligible. (C) 2014 Elsevier Inc. All rights reserved.
引用
收藏
页码:193 / 202
页数:10
相关论文
共 45 条
[1]  
[Anonymous], 1948, US BUR MIN B, V578, P19
[2]  
[Anonymous], ADV FISCHER TROPSCH
[3]   Preparation and characterization of well-dispersed and stable Co/SiO2 catalysts using the ammonia method [J].
Barbier, A ;
Hanif, A ;
Dalmon, JA ;
Martin, GA .
APPLIED CATALYSIS A-GENERAL, 1998, 168 (02) :333-343
[4]   Co/SiO2 catalysts prepared from CO2(CO)8 for CO hydrogenation into alcohols and hydrocarbons:: characterization by magnetic methods and temperature-programmed hydrogenation [J].
Barbier, A ;
Martin, GA ;
de la Piscina, PR ;
Homs, N .
APPLIED CATALYSIS A-GENERAL, 2001, 210 (1-2) :75-81
[5]   EDDY-CURRENT METHOD FOR MEASURING THE RESISTIVITY OF METALS [J].
BEAN, CP ;
DEBLOIS, RW ;
NESBITT, LB .
JOURNAL OF APPLIED PHYSICS, 1959, 30 (12) :1976-1980
[6]  
Bonneviot L., 1994, CATALYST CHARACTERIZ, P181
[7]   The Development of a Macro Kinetic Model for a Commercial Co/Pt/Al2O3 Fischer-Tropsch Catalyst [J].
Botes, F. Gideon ;
van Dyk, Braam ;
McGregor, Craig .
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, 2009, 48 (23) :10439-10447
[8]   How does activation affect the cobalt crystallographic structure? An in situ XRD and magnetic study [J].
Braconnier, L. ;
Landrivon, E. ;
Clemencon, I. ;
Legens, C. ;
Diehl, F. ;
Schuurman, Y. .
CATALYSIS TODAY, 2013, 215 :18-23
[9]   EQUILIBRIUM MEASUREMENTS IN THE NI3C-NI-CH4-H2 AND CO2C-CO-CH4-H2 SYSTEMS [J].
BROWNING, LC ;
EMMETT, PH .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1952, 74 (07) :1680-1682
[10]   Density Functional Theory Study of Iron and Cobalt Carbides for Fischer-Tropsch Synthesis [J].
Cheng, Jun ;
Hu, P. ;
Ellis, Peter ;
French, Sam ;
Kelly, Gordon ;
Lok, C. Martin .
JOURNAL OF PHYSICAL CHEMISTRY C, 2010, 114 (02) :1085-1093