Effect of calcination temperature on steam reforming activity of Ni-based pyrochlore catalysts

作     者：Daniel J.Haynes Dushyant Shekhawat David Berry Amitava Roy James J.Spivey Daniel J.Haynes;Dushyant Shekhawat;David Berry;Amitava Roy;James J.Spivey

作者机构：National Energy Technology LaboratoryU.S.Department of Energy3610 Collins Ferry RdMorgantownWV26507 USA Louisiana State UniversityCain Department of Chemical Engineering3307 Patrick Taylor HallBaton RougeLA70803USA 

出 版 物：《Journal of Rare Earths》 (稀土学报（英文版）)

年 卷 期：2020年第38卷第7期

页      面：711-718,I0002页

核心收录：

学科分类：081705[工学-工业催化] 08[工学] 0817[工学-化学工程与技术] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：Project supported by The Louisiana Board of Regents(LEQSF(2016-17)-ENH-TR-07) 

主　　题：Nickel Pyrochlore Methane Steam reforming Catalyst Lanthanum enrichment 

摘      要：This work served as the second part of a study evaluating the effect of calcination temperature(700-1000℃) on Ni-based lanthanum zirconate pyrochlore catalysts for methane steam reforming.A previous study(Haynes et ***.2017(43) 16744) provided a thorough characterization of the material properties for the catalysts used here,and this study focuses on the evaluation of catalytic *** activity was assessed by two different experimental studies:the effect of reaction temperature using a temperature programmed surface reaction(TPSR),and the effect of reaction *** results demonstrate a complex interaction between the Ni particles and surface LaOx species under the methane steam reforming ***,the material calcined at the lowest temperature(700℃) possesses the highest activity and selectivity,which is attributed to smaller and more welldispersed Ni particles on the surface,and,more importantly,a lesser degree La enrichment at the *** catalysts were deactivated by steam to NiO under all conditions tested,but at certain low reaction pressure(p=0.23 MPa) conditions the materials calcined at 700-900℃ are able to completely recover equilibrium activity in-situ that is then robust and stable under both low and high reaction pressures(p=1.8 MPa) suggesting the formation of a synergistic relationship between Ni and La for syngas ***,exposure of a fresh material to high reaction pressures leads to a rapid and irreversible loss in both CH4 conversion and syngas selectivity whether in the fresh(no pretreatment),or pretreated(steam,H2 or Ar only at 800℃) form for any *** mechanism for deactivation appears to be due to the presence of LaOx species that become mobile,possibly by the formation of La-OH,and covers the active Ni particles and inhibits sites responsible for the CH4 decomposition.