自动放排气阀原理图:翻译—语言是最厚的墙2

Previous studies of Cu-ZnO catalysts for the WGS reaction suggest that a synergy exists between copper and zinc oxide [29-31]. Mellor also found that stability of the catalyst improved significantly on adding zinc oxide, but that the total activity was lower because precipitated ZnO blocked part of the surface area [27,32]. From Fig. 1 it can be seen that small amounts of ZnO (<1 wt.%) did not affect the apparent copper surface area. Thus, the influence on the activity of the WGS reaction was insignificant (Fig. 4).

Vannice [33] studied the relationship of the activity over metal catalysts and the strength of interaction of CO with the metal. He postulated that the heat of adsorption of CO is a substantial parameter and developed a typical volcano-shaped plot. Thereafter, the kinetics of WGS reaction over supported metal catalysts were measured by Grenoble and Estadt [34]. A plot of turnover rate of the alumina-supported metals for WGS as a function of their periodic table position revealed that the igh-activity,low-temperature water gas shift catalyst is copper. Cobalt

was found to be the most active in Group VIII metals. However, such activity was found to be 50 times lower than that of metallic copper, based on turnover numbers measured at 673K [34]. Grenoble and Estadt [34] produced a volcano plot of turnover numbers versus heat of CO adsorption to explain their results.
In this study, both CO chemisorption and WGS activities were evaluated over the highest Co doped skeletal
copper sample and pure skeletal copper, and are listed in Table 2. The results show that CO chemisorption for the Co-doped skeletal copper catalyst is nearly half the value of that obtained for the pure skeletal copper catalyst, whilst the activity for the WGS reaction decreased almost 40-fold.