Alloy formation and surface segregation in zeolite-supported Pt-Pd bimetallic catalysts

被引：70

作者：

Hansen, PL

Molenbroek, AM

Ruban, AV

机构：

[1] TECH UNIV DENMARK,CTR ATOM SCALE MAT PHYS,DK-2800 LYNGBY,DENMARK

[2] TECH UNIV DENMARK,DEPT PHYS,DK-2800 LYNGBY,DENMARK

来源：

JOURNAL OF PHYSICAL CHEMISTRY B | 1997年 / 101卷 / 10期

关键词：

D O I：

10.1021/jp962771o

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：

We present extended X-ray absorption fine structure (EXAFS) and transmission electron microscopy (TEM) measurements on three zeolite-supported bimetallic Pt-Pd catalysts prepared by wet impregnation. Alloy formation and segregation of Pd to the surface of the small bimetallic particles is clearly identified. Ab initio LMTO calculations are used to predict segregation profiles of low-index single-crystal Pt-Pd alloy surfaces. Pd is found to be enriched at the surface. EMT potentials for Pt and Pd are adjusted in order to give the same segregation profiles at low-index single-crystal surfaces as linear muffin tin orbital (LMTO) calculations. Monte Carlo simulations based on the adjusted EMT potentials are then used to calculate the equilibrium structure of small bimetallic Pt-Pd particles. Coordination numbers derived from these equilibrium structures are compared with those derived from EXAFS analysis, and a good agreement is found.

引用

页码：1861 / 1868

页数：8

共 33 条

[21] SELF-INTERACTION CORRECTION TO DENSITY-FUNCTIONAL APPROXIMATIONS FOR MANY-ELECTRON SYSTEMS [J].

PERDEW, JP ;

ZUNGER, A .

PHYSICAL REVIEW B, 1981, 23 (10) :5048-5079

[22] SELF-CONSISTENT ELECTRONIC-STRUCTURE AND SEGREGATION PROFILES OF THE CU-NI (001) RANDOM-ALLOY SURFACE [J].

RUBAN, AV ;

ABRIKOSOV, IA ;

KATS, DY ;

GORELIKOV, D ;

JACOBSEN, KW ;

SKRIVER, HL .

PHYSICAL REVIEW B, 1994, 49 (16) :11383-11396

[23]

RUBAN AV, 1996, IN PRESS J MOL CATAL

[24]

Sinfelt J.H., 1983, EXXON MONOGRAPH

[25] APPLICATION OF EXAFS IN CATALYSIS - STRUCTURE OF BIMETALLIC CLUSTER CATALYSTS [J].

SINFELT, JH ;

VIA, GH ;

LYTLE, FW .

CATALYSIS REVIEWS-SCIENCE AND ENGINEERING, 1984, 26 (01) :81-140

[26]

Skriver H. L., 1984, The LMTO Method

[27] SELF-CONSISTENT GREEN-FUNCTION TECHNIQUE FOR SURFACES AND INTERFACES [J].

SKRIVER, HL ;

ROSENGAARD, NM .

PHYSICAL REVIEW B, 1991, 43 (12) :9538-9549

[28] AROMATIC HYDROGENATION CATALYSIS - A REVIEW [J].

STANISLAUS, A ;

COOPER, BH .

CATALYSIS REVIEWS-SCIENCE AND ENGINEERING, 1994, 36 (01) :75-123

[29]

Teo B. K., 1986, EXAFS BASIC PRINCIPL

[30] STRUCTURAL-ANALYSIS OF POLYMER-PROTECTED PD/PT BIMETALLIC CLUSTERS AS DISPERSED CATALYSTS BY USING EXTENDED X-RAY ABSORPTION FINE-STRUCTURE SPECTROSCOPY [J].

TOSHIMA, N ;

HARADA, M ;

YONEZAWA, T ;

KUSHIHASHI, K ;

ASAKURA, K .

JOURNAL OF PHYSICAL CHEMISTRY, 1991, 95 (19) :7448-7453

← 1 2 3 4 →