Elucidation of deactivation phenomena in cobalt catalyst for Fischer-Tropsch synthesis using SSITKA

Abstract Catalyst deactivation is a major problem in Fischer-Tropsch synthesis. It leads to a decrease in hydrocarbon productivity and loss of active sites in the expensive cobalt catalyst, and thus, undermines the overall efficiency of the technology. In the present paper, the effect of deactivation of silica-supported cobalt catalysts and their reductive rejuvenation on the number of active sites and their intrinsic activity (turnover frequency) in Fischer-Tropsch synthesis was studied using a combination of Steady State Isotopic Transient Kinetic Analysis (SSITKA) and catalyst characterization techniques. Catalyst characterization revealed that carbon deposition and agglomeration of cobalt nanoparticles during reaction were responsible for the deactivation. SSITKA experiments showed that the initial rate constant of 2.33 μmol g −1  s −1 had a loss of 67% of activity after 150 h on stream with a reduction in the amount of sites due to deposited carbon by 33.4 μmol g −1 . The carbon deposition leads to a decrease in the number of carbon chemisorbed intermediates which yield methane through their hydrogenation and desorption. The number of sites for reversible adsorption of CO is less affected by carbon deposition. The surface hydrogenation sites and surface sites favoring stronger reversible adsorption of carbon monoxide deactivate first during the first hours of Fischer-Tropsch synthesis. Catalyst rejuvenation in hydrogen lessens the amounts of deposited carbon species and partially releases the most active sites of carbon monoxide dissociative adsorption and stronger sites of carbon monoxide reversible adsorption. The transient isotopic methods provide an attractive tool to obtain precise information about the mechanisms of deactivation of cobalt catalysts in Fischer-Tropsch synthesis.

[1]  E. Steen,et al.  Fischer‐Tropsch Catalysts for the Biomass‐to‐Liquid (BTL)‐Process , 2008 .

[2]  A. M. Saib,et al.  Fundamental understanding of deactivation and regeneration of cobalt Fischer-Tropsch synthesis catalysts , 2010 .

[3]  O. Stéphan,et al.  Direct Evidence of Surface Oxidation of Cobalt Nanoparticles in Alumina-Supported Catalysts for Fischer–Tropsch Synthesis , 2014 .

[4]  W. Sachtler,et al.  On the activity of Fischer-Tropsch and methanation catalysts: A study utilizing isotopic transients , 1983 .

[5]  A. Khodakov,et al.  Transient studies of the elementary steps of Fischer–Tropsch synthesis , 2005 .

[6]  Enrique Iglesia,et al.  Design, synthesis, and use of cobalt-based Fischer-Tropsch synthesis catalysts , 1997 .

[7]  A. Datye,et al.  Carbon deposition as a deactivation mechanism of cobalt-based Fischer-Tropsch synthesis catalysts under realistic conditions , 2009 .

[8]  Anders Holmen,et al.  Effect of alumina phases on hydrocarbon selectivity in Fischer–Tropsch synthesis , 2010 .

[9]  Oliver R. Inderwildi,et al.  Fischer−Tropsch Mechanism Revisited: Alternative Pathways for the Production of Higher Hydrocarbons from Synthesis Gas , 2008 .

[10]  R. Zennaro,et al.  Detailed kinetics of the Fischer-Tropsch synthesis over Co-based catalysts containing sulphur , 2010 .

[11]  A. M. Efstathiou,et al.  The effect of La3+-doping of CeO2 support on the water-gas shift reaction mechanism and kinetics over Pt/Ce1−xLaxO2−δ , 2013 .

[12]  Manos Mavrikakis,et al.  Kinetically Relevant Steps and H2/D2 Isotope Effects in Fischer−Tropsch Synthesis on Fe and Co Catalysts , 2010 .

[13]  A. Khodakov,et al.  Pore Size Effects in Fischer Tropsch Synthesis over Cobalt-Supported Mesoporous Silicas , 2002 .

[14]  G. Jacobs,et al.  Fischer–Tropsch synthesis XAFS: XAFS studies of the effect of water on a Pt-promoted Co/Al2O3 catalyst , 2003 .

[15]  V. Lecocq,et al.  Influence of operating conditions in a continuously stirred tank reactor on the formation of carbon species on alumina supported cobalt Fischer–Tropsch catalysts , 2013 .

[16]  Pascal Fongarland,et al.  In situ XRD investigation of the evolution of alumina-supported cobalt catalysts under realistic conditions of Fischer-Tropsch synthesis. , 2010, Chemical communications.

[17]  H. Robota,et al.  The role of accumulated carbon in deactivating cobalt catalysts during FT synthesis in a slurry-bubble-column reactor , 2005 .

[18]  A. Holmen,et al.  Study of Pt-promoted cobalt CO hydrogenation catalysts , 1995 .

[19]  Jc Jaap Schouten,et al.  Mechanistic pathway for methane formation over an iron-based catalyst , 2008 .

[20]  M. D. Croon,et al.  Reactivity of surface carbonaceous intermediates on an iron-based Fischer-Tropsch catalyst , 2010 .

[21]  P. D. de Jongh,et al.  Control and impact of the nanoscale distribution of supported cobalt particles used in Fischer-Tropsch catalysis. , 2014, Journal of the American Chemical Society.

[22]  J. Hoebink,et al.  Steady-state isotopic transient kinetic analysis of the Fischer-Tropsch synthesis reaction over cobalt-based catalysts , 2001 .

[23]  V. Lecocq,et al.  Agglomeration at the Micrometer Length Scale of Cobalt Nanoparticles in Alumina‐Supported Fischer–Tropsch Catalysts in a Slurry Reactor , 2013 .

[24]  O. Stéphan,et al.  Molecular structure and localization of carbon species in alumina supported cobalt Fischer–Tropsch catalysts in a slurry reactor , 2014 .

[25]  P. Roussel,et al.  Structure and catalytic performance of Pt-promoted alumina-supported cobalt catalysts under realistic conditions of Fischer–Tropsch synthesis , 2011 .

[26]  De Chen,et al.  Understanding the kinetics and Re promotion of carbon nanotube supported cobalt catalysts by SSITKA , 2012 .

[27]  J. Bitter,et al.  On the origin of the cobalt particle size effects in Fischer-Tropsch catalysis. , 2009, Journal of the American Chemical Society.

[28]  V. Dijk The Fischer-Tropsch synthesis : a mechanistic study using transient isotopic tracing , 2001 .

[29]  B. Weckhuysen,et al.  Combined Operando X‐ray Diffraction/Raman Spectroscopy of Catalytic Solids in the Laboratory: The Co/TiO2 Fischer–Tropsch Synthesis Catalyst Showcase , 2016, ChemCatChem.

[30]  A. M. Saib,et al.  Providing fundamental and applied insights into Fischer-Tropsch catalysis : Sasol-Eindhoven University of Technology collaboration , 2016 .

[31]  A. M. Efstathiou The CO/H2 reaction on Rh/MgO studied by transient isotopic methods , 1991 .

[32]  M. Rønning,et al.  Steady state isotopic transient kinetic analysis (SSITKA) of CO hydrogenation on different Co catalysts , 2005 .

[33]  Sébastien Paul,et al.  Effects of co-feeding with nitrogen-containing compounds on the performance of supported cobalt and iron catalysts in Fischer–Tropsch synthesis , 2016 .

[34]  M. Dry,et al.  In situ magnetometer study on the formation and stability of cobalt carbide in Fischer–Tropsch synthesis , 2014 .

[35]  Jia Yang,et al.  Reaction mechanism of CO activation and methane formation on Co Fischer-Tropsch catalyst: A combined DFT, transient, and steady-state kinetic modeling , 2013 .

[36]  J. Goodwin,et al.  Effect of zirconia-modified alumina on the properties of Co/γ-Al2O3 catalysts , 2003 .

[37]  Xue-qing Gong,et al.  CO dissociation and O removal on Co(0001): a density functional theory study , 2004 .

[38]  C. Bennett,et al.  The COH2 reaction on RhAl2O3: I. Steady-state and transient kinetics , 1989 .

[39]  J. Goodwin,et al.  Characterization of Catalytic Surfaces by Isotopic-Transient Kinetics during Steady-State Reaction , 1995 .

[40]  Q. Ge,et al.  Adsorption and activation of CO over flat and stepped Co surfaces: a first principles analysis. , 2006, The journal of physical chemistry. B.

[41]  Jinghua Guo,et al.  Size-dependent dissociation of carbon monoxide on cobalt nanoparticles. , 2013, Journal of the American Chemical Society.

[42]  E. Steen,et al.  Mechanistic Issues in Fischer–Tropsch Catalysis , 2011 .

[43]  Michel Che,et al.  Characterization of Solid Materials and Heterogeneous Catalysts: From Structure to Surface Reactivity , 2012 .

[44]  M. Virginie,et al.  Impact and Detailed Action of Sulfur in Syngas on Methane Synthesis on Ni/γ-Al2O3 Catalyst , 2014 .

[45]  Yongqing Zhang,et al.  FISCHER-TROPSCH SYNTHESIS: DEACTIVATION OF NOBLE METAL PROMOTED CO/AL2O3 CATALYSTS , 2002 .

[46]  A. Holmen,et al.  The effect of water on cobalt Fischer-Tropsch catalysts studied by steady-state isotopic transient kinetic analysis (SSITKA) , 1997 .

[47]  J. Dalmon,et al.  Cobalt Fischer-Tropsch synthesis : deactivation by oxidation? , 2007 .

[48]  S. Piche,et al.  Deactivation of a Co/Al2O3 Fischer–Tropsch catalyst by water-induced sintering in slurry reactor: Modeling and experimental investigations , 2013 .

[49]  James G. Goodwin,et al.  Effect of K promotion of Fe and FeMn Fischer–Tropsch synthesis catalysts: Analysis at the site level using SSITKA , 2008 .

[50]  Wei Chu,et al.  Advances in the development of novel cobalt Fischer-Tropsch catalysts for synthesis of long-chain hydrocarbons and clean fuels. , 2007, Chemical reviews.

[51]  M. Dry,et al.  The Fischer–Tropsch process: 1950–2000 , 2002 .

[52]  Yongqing Zhang,et al.  Fischer–Tropsch synthesis: support, loading, and promoter effects on the reducibility of cobalt catalysts , 2002 .

[53]  J. Wintterlin,et al.  In situ scanning tunneling microscopy of the poisoning of a Co(0 0 0 1) Fischer–Tropsch model catalyst by sulfur , 2015 .

[54]  K. Cheng,et al.  The Role of Steric Effects and Acidity in the Direct Synthesis of iso‐Paraffins from Syngas on Cobalt Zeolite Catalysts , 2016 .

[55]  Anders Holmen,et al.  Deactivation of cobalt based Fischer―Tropsch catalysts: A review , 2010 .

[56]  Anders Holmen,et al.  SSITKA analysis of CO hydrogenation on Zn modified cobalt catalysts , 2013 .

[57]  C. Bennett,et al.  The CO/H2 reaction on Rh/Al2O3II. Kinetic study by transient isotopic methods , 1989 .

[58]  G. Jacobs,et al.  The application of synchrotron methods in characterizing iron and cobalt Fischer–Tropsch synthesis catalysts , 2013 .

[59]  P. Biloen,et al.  Transient kinetic methods , 1983 .

[60]  De Chen,et al.  Recent Approaches in Mechanistic and Kinetic Studies of Catalytic Reactions Using SSITKA Technique , 2014 .