费托催化剂η-Fe_2C(011)上CH_4形成及C-C耦合机理研究
|
摘要
Fe_2C是低温Fe基费托催化剂的主要活性相,研究其上费托反应机理具有十分重要的意义。从原子尺度上通过密度泛函理论(DFT)计算研究了Fe_2C稳定晶相η-Fe_2C的(011)表面上甲烷形成和C—C耦合的反应机理。计算结果表明,η-Fe_2C(011)表面上甲烷形成的有效能垒为1.03 eV,其低于CH_i+CH_j耦合反应的有效能垒(1.52～2.98 eV),且最可能的C—C耦合反应路径为C+CH_3。进一步比较研究了η-Fe_2C(011)表面与其他Fe基费托催化剂表面之间的CH_4和C_(2+)选择性差异,发现选择性高度敏感于Fe基催化剂的表面与体相结构,其中η-Fe_2C(011)表面具有较高的甲烷选择性。
Fe_2C is the main active phase of low temperature Fe-based Fischer-Tropsch catalysts.It is of great significance to study the mechanism of Fischer-Tropsch reaction.Herein,spin-polarized density functional theory(DFT)calculations are performed to investigate the mechanism of CH_4formation and C—C coupling on theη-Fe_2C(011)surface,where this crystal phase is thermodynamically stable.The calculated results show that the effective barrier of CH_4 formation on such surface is 1.03 eV,lower than those of C—C coupling,and the C+CH_3is the most likely C—C coupling pathways.Subsequently,the effective barrier difference between the CH_4 formation and C_1—C_1 coupling is used as a descriptor to compare the difference of the Ficher-Tropsch synthesis(FTS)selectivity between the η-Fe_2C(011)surface and other Fe-based catalysts surfaces.The FTS selectivity is found to be highly sensitive to the crystal phases and surfaces of Fe-based catalysts,and theη-Fe_2C(011) surface shows relatively high CH_4 selectivity.
Fe_2C is the main active phase of low temperature Fe-based Fischer-Tropsch catalysts.It is of great significance to study the mechanism of Fischer-Tropsch reaction.Herein,spin-polarized density functional theory(DFT)calculations are performed to investigate the mechanism of CH_4formation and C—C coupling on theη-Fe_2C(011)surface,where this crystal phase is thermodynamically stable.The calculated results show that the effective barrier of CH_4 formation on such surface is 1.03 eV,lower than those of C—C coupling,and the C+CH_3is the most likely C—C coupling pathways.Subsequently,the effective barrier difference between the CH_4 formation and C_1—C_1 coupling is used as a descriptor to compare the difference of the Ficher-Tropsch synthesis(FTS)selectivity between the η-Fe_2C(011)surface and other Fe-based catalysts surfaces.The FTS selectivity is found to be highly sensitive to the crystal phases and surfaces of Fe-based catalysts,and theη-Fe_2C(011) surface shows relatively high CH_4 selectivity.
引文
[1]Zhang Q,Kang J,Wang Y.Development of novel catalysts for Fischer-Tropsch synthesis:tuning the product selectivity[J].ChemCatChem,2010,2(9):1030-1058.
[2]王野,成康,张庆红.一氧化碳加氢制碳氢化合物反应选择性的调控[J].中国科学:化学,2012,42(4):263-375.Wang Y,Cheng K,Zhang Q H.Selectivity tuning for the hydrogenation of carbon monoxide into hydrocarbons[J].Scientia Sinica Chimica,2012,42(4):263-375.
[3]Jager B,Espinoza R.Advances in low temperature FischerTropsch synthesis[J].Catalysis Today,1995,23:17-28.
[4]Xu J,Yang Y,Li Y W.Fischer-Tropsch synthesis process development:steps from fundamentals to industrial practices[J].Current Opinion in Chemical Engineering,2013,2:354-362.
[5]Jahangiri H,Bennett J,Mahjoubi P,et al.A review of advanced catalyst development for Fischer-Tropsch synthesis of hydrocarbons from biomass derived syngas[J].Catalysis Science&Technology,2014,4(8):2210-2229.
[6]Schulz H.Short history and present trends of Fischer-Tropsch synthesis[J].Applied Catalysis A:General,1999,186:3-12.
[7]温晓东,杨勇,李永旺,等.费托合成铁基催化剂的设计基础:从理论走向实践[J].中国科学:化学,2017,(11):72-85.Wen X D,Yang Y,Li Y W,et al.The design principle of ironbased catalysts for Fischer-Tropsch synthesis:from theory to practice[J].Scientia Sinica Chimica,2017,(11):72-85.
[8]de Smit E,Cinquini F,Weckhuysen B M,et al.Stability and reactivity of?-χ-θiron carbide catalyst phases in FischerTropsch synthesis:controllingμC[J].Journal of the American Chemical Society,2010,132:14928-14941.
[9]Xu K,Sun B,Qiao M H,et al.ε-Iron carbide as a lowtemperature Fischer-Tropsch synthesis catalyst[J].Nature Communication,2014,5:5783-5790.
[10]Liu X W,Zhao S,Meng Y.M?ssbauer spectroscopy of iron carbides:from prediction to experimental confirmation[J].Scientific Reports,2016,6:26184.
[11]Jose?G R C,Maarten K S,Marie-Francoise R.First principle study on the adsorption of hdrocarbon chains involved in FischerTropsch synthesis over iron carbides[J].The Journal of Physical Chemistry C,2017,121:25052-25063.
[12]Le Caer G,Dubois J M,Bussiere P,et al.Characterization by Mossbauer spectroscopy of iron carbides formed by FischerTropsch synthesis[J].The Journal of Physical Chemistry,1982,86(24):4799-4808.
[13]Fang C M,Sluiter M H F,van Huis M A,et al.Origin of predominance of cementite among iron carbides in steel at elevated temperature[J].Physical Review Letters,2010,105(5):055503.
[14]Bao L L,Huo C F,Li Y W,et al.Structure and stability of the crystal Fe2C and low index surfaces[J].Journal of Fuel Chemistry and Technology,2009,37:104-108.
[15]Chen W,Lin T J,Sun Y H,et al.Recent advances in the investigation of nanoeffects of Fischer-Tropsch catalysts[J].Catalysis Today,2018,311:8-22.
[16]Pham T H,Qi Y,Yang J,et al.Insights into Ha?gg iron-carbidecatalyzed Fischer-Tropsch synthesis:suppression of CH4formation and enhancement of C-C coupling onχ-Fe5C2(510)[J].ACS Catalysis,2015,5(4):2203-2208.
[17]Wang Y,Li Y,Huang S,et al.Insight into CH4formation and chain growth mechanism of Fischer-Tropsch synthesis onθ-Fe3C(031)[J].Chemical Physics Letters,2017,682:115-121.
[18]Perdew J P,Yue W.Accurate and simple density functional for the electronic exchange energy:generalized gradient approximation[J].Physical Review B,1986,33(12):8800.
[19]Perdew J P,Burke K,Ernzerhof M.Generalized gradient70approximation made simple[J].Physical Review Letters,1996,77(18):3865.
[20]Kresse G,Joubert D.From ultrasoft pseudopotentials to the projector augmented-wave method[J].Physical Review B,1999,59(3):1758.
[21]Henkelman G,Jónsson H.A dimer method for finding saddle points on high dimensional potential surfaces using only first derivatives[J].The Journal of Chemical Physics,1999,111(15):7010-7022.
[22]Huo C F,Li Y W,Wang J,et al.Insight into CH4formation in iron-catalyzed Fischer-Tropsch synthesis[J].Journal of the American Chemical Society,2009,131(41):14713-14721.
[23]宋楠,段学志,周兴贵,等.费托催化剂η-Fe2C(011)上CO吸附与活化行为[J].陕西师范大学学报(自然科学版),2019,47(1):13-19.Song N,Duan X Z,Zhou X G,et al.Adsorption and activation of CO onη-Fe2C(011)surface of Fischer-Tropsch synthesis catalyst[J].Journal of Shaanxi Normal University(Natural Science Edition),2019,47(1):13-19.
[24]Lo J M H,Ziegler T.Density functional theory and kinetic studies of methanation on iron surface[J].The Journal of Physical Chemistry C,2007,111(29):11012-11025.
[25]Govender A,Curulla F D,Niemantsverdriet J W.A density functional theory study on the effect of zero-point energy corrections on the methanation profile on Fe(100)[J].ChemPhysChem,2012,13(6):1591-1596.
[26]Cheng J,Hu P,Ellis P,et al.Density functional theory study of iron and cobalt carbides for Fischer-Tropsch synthesis[J].The Journal of Physical Chemistry C,2010,114(2):1085-1093.
[27]Fischer F,Tropsch H.The preparation of synthetic oil mixtures(synthol)from carbon monoxide and hydrogen[J].BrennstoffChem,1923,4:276-285.
[28]Pichler H,Schultz H.New insights in the area of the synthesis of hydrocarbons from CO and H2[J].Chem.Ing.Tech.,1970,12(18):1160-1174.
[29]Kummer J T,Emmett P H.Fischer-Tropsch synthesis mechanism studies.The addition of radioactive alcohols to the synthesis gas[J].Journal of the American Chemical Society,1953,75(21):5177-5183.
[30]Ciob??c?I M,Kramer G J,Ge Q,et al.Mechanisms for chain growth in Fischer-Tropsch synthesis over Ru(0001)[J].Journal of Catalysis,2002,212(2):136-144.
[31]Liu Z P,Hu P.A new insight into Fischer-Tropsch synthesis[J].Journal of the American Chemical Society,2002,124(39):11568-11569.
[32]Lo J M H,Ziegler T.Theoretical studies of the formation and reactivity of C2hydrocarbon species on the Fe(100)surface[J].The Journal of Physical Chemistry C,2007,111(35):13149-13162.
[33]Zhao Y H,Sun K,Ma X,et al.Carbon chain growth by formyl insertion on rhodium and cobalt catalysts in syngas conversion[J].Angewandte Chemie International Edition,2011,50(23):5335-5338.
[34]Michaelides A,Hu P.Insight into microscopic reaction pathways in heterogeneous catalysis[J].Journal of the American Chemical Society,2000,122(40):9866-9867.
[35]Cheng J,Gong X Q,Hu P,et al.A quantitative determination of reaction mechanisms from density functional theory calculations:Fischer-Tropsch synthesis on flat and stepped cobalt surfaces[J].Journal of Catalysis,2008,254(2):285-295.
[36]Cheng J,Hu P,Ellis P,et al.An energy descriptor to quantify methane selectivity in Fischer-Tropsch synthesis:a density functional theory study[J].The Journal of Physical Chemistry C,2009,113(20):8858-8863.
[37]Peter M M,Valerio Z.The role of electrophilic species in the Fischer-Tropsch reaction[J].Chemical Communications,2009,40(27):1619-1634.
[38]Cheng J,Hu P,Ellis P,et al.Chain growth mechanism in FischerTropsch synthesis:a DFT study of C-C coupling over Ru,Fe,Rh,and Re surfaces[J].The Journal of Physical Chemistry C,2008,112:6082-6086.
[39]Cao D B,Li Y W,Jiao H J,et al.Chain growth mechanism of Fischer-Tropsch synthesis on Fe5C2(001)[J].Journal of Molecular Catalysis A:Chemical,2011,346:55-69.
[40]Zhao Y H,Sun K,Li W X,et al.Carbon chain growth by formyl insertion on rhodium and cobalt catalysts in syngas conversion[J].Angewandte Chemie International Edition,2011,50:5335-5338.
[41]Sorescu D C.First-principles calculations of the adsorption and hydrogenation reactions of CHx(x=0,4)species on a Fe(100)surface[J].Physical Review B,2006,73(15):155420.
[42]Cao D B,Li Y W,Wang J,et al.Adsorption and reaction of surface carbon species on Fe5C2(001)[J].The Journal of Physical Chemistry C,2008,112(38):14883-14890.
[43]Park J Y,Lee Y J,Khanna P K,et al.Alumina-supported iron oxide nanoparticles as Fischer-Tropsch catalysts:effect of particle size of iron oxide[J].Journal of Molecular Catalysis A:Chemical,2010,323(1/2):84-90.
[44]Torres G H M,Bitter J H,Davidian T,et al.Iron particle size effects for direct production of lower olefins from synthesis gas[J].Journal of the American Chemical Society,2012,134(39):16207-16215.
[45]Govender A,Curulla-FerréD,Pérez-Jigato M,et al.Firstprinciples elucidation of the surface chemistry of the C2Hx(x=0-6)adsorbate series on Fe(100)[J].Molecules,2013,18(4):3806-3824.
[2]王野,成康,张庆红.一氧化碳加氢制碳氢化合物反应选择性的调控[J].中国科学:化学,2012,42(4):263-375.Wang Y,Cheng K,Zhang Q H.Selectivity tuning for the hydrogenation of carbon monoxide into hydrocarbons[J].Scientia Sinica Chimica,2012,42(4):263-375.
[3]Jager B,Espinoza R.Advances in low temperature FischerTropsch synthesis[J].Catalysis Today,1995,23:17-28.
[4]Xu J,Yang Y,Li Y W.Fischer-Tropsch synthesis process development:steps from fundamentals to industrial practices[J].Current Opinion in Chemical Engineering,2013,2:354-362.
[5]Jahangiri H,Bennett J,Mahjoubi P,et al.A review of advanced catalyst development for Fischer-Tropsch synthesis of hydrocarbons from biomass derived syngas[J].Catalysis Science&Technology,2014,4(8):2210-2229.
[6]Schulz H.Short history and present trends of Fischer-Tropsch synthesis[J].Applied Catalysis A:General,1999,186:3-12.
[7]温晓东,杨勇,李永旺,等.费托合成铁基催化剂的设计基础:从理论走向实践[J].中国科学:化学,2017,(11):72-85.Wen X D,Yang Y,Li Y W,et al.The design principle of ironbased catalysts for Fischer-Tropsch synthesis:from theory to practice[J].Scientia Sinica Chimica,2017,(11):72-85.
[8]de Smit E,Cinquini F,Weckhuysen B M,et al.Stability and reactivity of?-χ-θiron carbide catalyst phases in FischerTropsch synthesis:controllingμC[J].Journal of the American Chemical Society,2010,132:14928-14941.
[9]Xu K,Sun B,Qiao M H,et al.ε-Iron carbide as a lowtemperature Fischer-Tropsch synthesis catalyst[J].Nature Communication,2014,5:5783-5790.
[10]Liu X W,Zhao S,Meng Y.M?ssbauer spectroscopy of iron carbides:from prediction to experimental confirmation[J].Scientific Reports,2016,6:26184.
[11]Jose?G R C,Maarten K S,Marie-Francoise R.First principle study on the adsorption of hdrocarbon chains involved in FischerTropsch synthesis over iron carbides[J].The Journal of Physical Chemistry C,2017,121:25052-25063.
[12]Le Caer G,Dubois J M,Bussiere P,et al.Characterization by Mossbauer spectroscopy of iron carbides formed by FischerTropsch synthesis[J].The Journal of Physical Chemistry,1982,86(24):4799-4808.
[13]Fang C M,Sluiter M H F,van Huis M A,et al.Origin of predominance of cementite among iron carbides in steel at elevated temperature[J].Physical Review Letters,2010,105(5):055503.
[14]Bao L L,Huo C F,Li Y W,et al.Structure and stability of the crystal Fe2C and low index surfaces[J].Journal of Fuel Chemistry and Technology,2009,37:104-108.
[15]Chen W,Lin T J,Sun Y H,et al.Recent advances in the investigation of nanoeffects of Fischer-Tropsch catalysts[J].Catalysis Today,2018,311:8-22.
[16]Pham T H,Qi Y,Yang J,et al.Insights into Ha?gg iron-carbidecatalyzed Fischer-Tropsch synthesis:suppression of CH4formation and enhancement of C-C coupling onχ-Fe5C2(510)[J].ACS Catalysis,2015,5(4):2203-2208.
[17]Wang Y,Li Y,Huang S,et al.Insight into CH4formation and chain growth mechanism of Fischer-Tropsch synthesis onθ-Fe3C(031)[J].Chemical Physics Letters,2017,682:115-121.
[18]Perdew J P,Yue W.Accurate and simple density functional for the electronic exchange energy:generalized gradient approximation[J].Physical Review B,1986,33(12):8800.
[19]Perdew J P,Burke K,Ernzerhof M.Generalized gradient70approximation made simple[J].Physical Review Letters,1996,77(18):3865.
[20]Kresse G,Joubert D.From ultrasoft pseudopotentials to the projector augmented-wave method[J].Physical Review B,1999,59(3):1758.
[21]Henkelman G,Jónsson H.A dimer method for finding saddle points on high dimensional potential surfaces using only first derivatives[J].The Journal of Chemical Physics,1999,111(15):7010-7022.
[22]Huo C F,Li Y W,Wang J,et al.Insight into CH4formation in iron-catalyzed Fischer-Tropsch synthesis[J].Journal of the American Chemical Society,2009,131(41):14713-14721.
[23]宋楠,段学志,周兴贵,等.费托催化剂η-Fe2C(011)上CO吸附与活化行为[J].陕西师范大学学报(自然科学版),2019,47(1):13-19.Song N,Duan X Z,Zhou X G,et al.Adsorption and activation of CO onη-Fe2C(011)surface of Fischer-Tropsch synthesis catalyst[J].Journal of Shaanxi Normal University(Natural Science Edition),2019,47(1):13-19.
[24]Lo J M H,Ziegler T.Density functional theory and kinetic studies of methanation on iron surface[J].The Journal of Physical Chemistry C,2007,111(29):11012-11025.
[25]Govender A,Curulla F D,Niemantsverdriet J W.A density functional theory study on the effect of zero-point energy corrections on the methanation profile on Fe(100)[J].ChemPhysChem,2012,13(6):1591-1596.
[26]Cheng J,Hu P,Ellis P,et al.Density functional theory study of iron and cobalt carbides for Fischer-Tropsch synthesis[J].The Journal of Physical Chemistry C,2010,114(2):1085-1093.
[27]Fischer F,Tropsch H.The preparation of synthetic oil mixtures(synthol)from carbon monoxide and hydrogen[J].BrennstoffChem,1923,4:276-285.
[28]Pichler H,Schultz H.New insights in the area of the synthesis of hydrocarbons from CO and H2[J].Chem.Ing.Tech.,1970,12(18):1160-1174.
[29]Kummer J T,Emmett P H.Fischer-Tropsch synthesis mechanism studies.The addition of radioactive alcohols to the synthesis gas[J].Journal of the American Chemical Society,1953,75(21):5177-5183.
[30]Ciob??c?I M,Kramer G J,Ge Q,et al.Mechanisms for chain growth in Fischer-Tropsch synthesis over Ru(0001)[J].Journal of Catalysis,2002,212(2):136-144.
[31]Liu Z P,Hu P.A new insight into Fischer-Tropsch synthesis[J].Journal of the American Chemical Society,2002,124(39):11568-11569.
[32]Lo J M H,Ziegler T.Theoretical studies of the formation and reactivity of C2hydrocarbon species on the Fe(100)surface[J].The Journal of Physical Chemistry C,2007,111(35):13149-13162.
[33]Zhao Y H,Sun K,Ma X,et al.Carbon chain growth by formyl insertion on rhodium and cobalt catalysts in syngas conversion[J].Angewandte Chemie International Edition,2011,50(23):5335-5338.
[34]Michaelides A,Hu P.Insight into microscopic reaction pathways in heterogeneous catalysis[J].Journal of the American Chemical Society,2000,122(40):9866-9867.
[35]Cheng J,Gong X Q,Hu P,et al.A quantitative determination of reaction mechanisms from density functional theory calculations:Fischer-Tropsch synthesis on flat and stepped cobalt surfaces[J].Journal of Catalysis,2008,254(2):285-295.
[36]Cheng J,Hu P,Ellis P,et al.An energy descriptor to quantify methane selectivity in Fischer-Tropsch synthesis:a density functional theory study[J].The Journal of Physical Chemistry C,2009,113(20):8858-8863.
[37]Peter M M,Valerio Z.The role of electrophilic species in the Fischer-Tropsch reaction[J].Chemical Communications,2009,40(27):1619-1634.
[38]Cheng J,Hu P,Ellis P,et al.Chain growth mechanism in FischerTropsch synthesis:a DFT study of C-C coupling over Ru,Fe,Rh,and Re surfaces[J].The Journal of Physical Chemistry C,2008,112:6082-6086.
[39]Cao D B,Li Y W,Jiao H J,et al.Chain growth mechanism of Fischer-Tropsch synthesis on Fe5C2(001)[J].Journal of Molecular Catalysis A:Chemical,2011,346:55-69.
[40]Zhao Y H,Sun K,Li W X,et al.Carbon chain growth by formyl insertion on rhodium and cobalt catalysts in syngas conversion[J].Angewandte Chemie International Edition,2011,50:5335-5338.
[41]Sorescu D C.First-principles calculations of the adsorption and hydrogenation reactions of CHx(x=0,4)species on a Fe(100)surface[J].Physical Review B,2006,73(15):155420.
[42]Cao D B,Li Y W,Wang J,et al.Adsorption and reaction of surface carbon species on Fe5C2(001)[J].The Journal of Physical Chemistry C,2008,112(38):14883-14890.
[43]Park J Y,Lee Y J,Khanna P K,et al.Alumina-supported iron oxide nanoparticles as Fischer-Tropsch catalysts:effect of particle size of iron oxide[J].Journal of Molecular Catalysis A:Chemical,2010,323(1/2):84-90.
[44]Torres G H M,Bitter J H,Davidian T,et al.Iron particle size effects for direct production of lower olefins from synthesis gas[J].Journal of the American Chemical Society,2012,134(39):16207-16215.
[45]Govender A,Curulla-FerréD,Pérez-Jigato M,et al.Firstprinciples elucidation of the surface chemistry of the C2Hx(x=0-6)adsorbate series on Fe(100)[J].Molecules,2013,18(4):3806-3824.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |