Support effect and active sites on promoted ruthenium catalysts for ammonia synthesis

被引：87

作者：

Hansen, TW ^{[1
]}

Hansen, PL ^{[1
]}

Dahl, S ^{[1
]}

Jacobsen, CJH ^{[1
]}

机构：

[1] Haldor Topsoe Res Labs, DK-2800 Lyngby, Denmark

来源：

CATALYSIS LETTERS | 2002年 / 84卷 / 1-2期

关键词：

catalytic ammonia synthesis; promoters; TEM; EELS; ruthenium; barium;

D O I：

10.1023/A:1021028718491

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：

The catalytic activities of three supported, barium-promoted ruthenium catalysts for ammonia synthesis are reported. The three supports are silicon nitride (Si3N4), magnesium aluminum spinel (MgAl2O4), and graphitized carbon (C). The effect of the promoter on the activity is strongly dependent on the choice of support material in accordance with several previous observations. Here, this dependence is ascribed to a difference in the affinity of the promoter for the different supports. It is shown how it is possible to image the barium promoter present on the surface of ruthenium crystals in passivated catalysts by conventional high-resolution transmission electron microscopy (HRTEM). By comparison with in situ HRTEM images obtained lately from similar catalysts, and with reference to recent density functional theory (DFT) calculations, we suggest that active B-5-type sites on the surfaces of the ruthenium crystals are promoted by nearby promoter atoms via electrostatic interactions.

引用

页码：7 / 12

页数：6

共 34 条

[1] ACTIVATION OF NITROGEN BY ALKALI-METAL PROMOTED TRANSITION-METAL .1. AMMONIA SYNTHESIS OVER RUTHENIUM PROMOTED BY ALKALI-METAL [J].