Water gas shift activity

Pennline et al.32 used bifunctional Co/ThO/ZSM-5 catalysts at 280°C, 21 bar, H2/CO = 1 in the FTS. XRD of the used catalyst indicated that cobalt carbide is present. They found that the relative amount of the carbide species is larger on the used catalyst operated at 280°C than on the used catalyst operated at 320°C. They argued that this is because cobalt carbide begins to decompose around 300°C. Since this catalyst lacked high water gas shift activity, and a low feed gas ratio of... 

Panagiotopoulou, P., Christodoulakis, A., Kondarides, D.I., and Boghosian, S. 2006. Particle size effects on the reducibility of titanium dioxide and its relation to the water-gas shift activity of Pt/Ti02 catalysts. J. Catal. 240 114—25. 

The additional CO conversion that is observed after a change from lean to rich exhaust may be due to a temporarily enhanced water-gas shift activity as proposed by Schlatter and Mitchell (9), and may also be due to reaction of CO with oxygen bound to Ce in the catalyst. 

Table 3 Water-gas shift activities of various metal carbonyl catalysts32...

Imanaka—heterogenization of Rh complexes. In 1991, Imanaka and coworkers124 reported the heterogenization of Rh complexes by binding them to aminated polymers. As discussed previously, these findings led to fruitful research by Ford, Pardey, and others. The isolated polymer-bound Rh carbonyl anion complex was found to be reusable for reactions such as water-gas shift and reduction of nitro compounds. The polymer-bound Rh complexes were characterized by infrared spectroscopy. Water-gas shift activity (80 mol H2 per mol Rh6(CO)i6 in 24 hours) was recorded using the Rh complexes at 100 °C with 0.92 atm of CO, 2.16 ml H20, 0.05 mmol Rh6(CO)16, aminated polystyrene, 5.0 mmol of N, 5.56 ml ethoxyethanol and reduction of nitro-compounds (e.g., aliphatic nitro compounds to nitriles, oximes to nitriles, hydroxylamines to nitriles, and N-oxides to amines) occurred at 40 °C. 

Grenoble and coworkers229 reported an important influence of the support on the water-gas shift activity of various metal catalysts. For example, the rate increased an order of magnitude when Pt was supported on alumina versus silica. Turnover numbers for alumina-supported metal catalysts decreased in the order Cu, Re, Co, Ru, Ni, Pt, Os, Au, Fe, Pd, Rh, and Ir, whereby the activity varied by 3 orders of magnitude, suggesting a correlation between activity of the metal and the heat of adsorption. To describe these differences in activity, the authors used a bifunctional model, involving chemisorption of water on alumina and CO on the metal, followed by association of the CO with the water to form a formic acid-like formate species, with subsequent decomposition via dehydrogenation on the metal sites (Scheme 55). 

Mendelovici and Steinberg—Pt/Ce02 exhibits good water-gas shift activity. 

Table 124 Water-gas shift activity at 120 °C for treated 3% or 5%Au/a-Fe203 catalysts using a feed containing 57.5 cm3/h CO and 921.5 cm3/h using 0.5 g catalyst after 3 hours onstream. Relationship with catalyst reducibility523... 

It is worthy to note that numerous researchers have recently observed high catalytic activity for methanol steam reforming over Pd/Zn and Pt/Zn catalysts,528-534 and it would seem that these catalysts likely have potential for low temperature water-gas shift activity. 

Zirconia-modified silica impregnated with Co2(CO)s and activated under H2 at 300 °C renders a catalyst more active and selective to diesel fraction, in the CO hydrogenation reaction, than that conventionally prepared from a nitrate salt solution. The selectivity patterns followed a Schulz-Flory distribution and catalysts prepared from carbonyl precursor exhibited low water-gas shift activity [146]. 

In the third regime, at high [H2O], where Forster noted high water gas shift activity as well as carbonylation, the ionic species now included substantial amounts of the ionic hydride complex [IrH ( 0)213] . 

The ratio of C02 produced to CO converted is 0.5 for this case. The C02/ CO ratios presented in Table 19.2 show the water-gas shift activity increased in the order Fe carbide < precipitated < ultrafine oxide. The ability of the Fe carbide catalyst to suppress the water-gas shift enables it to have a high hydrocarbon production. 

Low Temperature Water Gas Shift Activity of Ruthenium in Zeolites in Relation to Its Chemistry... 

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