Coke oxidation iron effect

Hydrocarbons and carbonized or coke deposits can be removed by chromic acid. The chromic acid oxidizes the binders holding the deposits together. Use a 10 to 20% solution for 12 to 24 hours at 190 to 200 °F. Chromic acid cannot be effectively inhibited and is not suitable for cleaning copper, brass, aluminum, zinc, or cast iron because these are all rapidly attacked. 

Quantitative Estimates of Density Variations. Quantitative estimates of the relative contribution of Factors 1-5 to changes in catalyst density are given in Table IX. In carrying out these calculations, the average skeletal density of coke on catalyst was taken to be 1.2 g/cc (Appendix A). Nickel, vanadium, and rare earth were assumed to be present as the oxides NiO, V20A, and RE203 with densities of 6.7, 4.3, and 6.9, respectively. Similar assumptions were made for iron and titanium (Appendix A), but the effect of Fe and Ti was included only for the heavier Fractions E, F, and H, which exhibited increased levels of these two metals (Table III). For the float Fractions A-F, this approach, based on bulk oxide densities, is expected to overestimate the density increase due to metals that are present as well-dispersed species. 

Carbon Dioxide. As the debate of the effect of greenhouse gases rages on, the simple fact remains that carbon dioxide production is one of the known side reactions of most metal-production operations. Carbon is an effective metal reductant. Coke is used to produce pig iron from iron oxide ores and lead from sulfide ores in blast furnaces, carbon electrodes are used to produce aluminum from bauxite leaching products, and coal is used in the reduction of zinc oxide in retorting furnaces. All told, the resulting product of metal reduction is the oxidation of carbon to carbon dioxide. It is important to keep in mind that the production of carbon dioxide has been reduced dramatically since the start of the Industrial Revolution of the late nineteenth-century. This is best exemplified by the history of steel making in the world. 

In marked contrast to the effects observed with iron, vanadium and copper oxides, prior impregnation of silica-alumina with nickel oxide led to a considerable increase in the initial rate of subsequent coke gasification, up to a coke conversion level of a>30% (Figure 2). 

Kiylov et aZ. studied the catalytic reaction of methane with carbon dioxide over MnO -containing catalysts for syngas production. The effect of the modification of nickel by different additives, such as copper, chromium, iron and manganese oxides, was evaluated and the best effect was obtained with manganese oxide an increase of manganese content originated an increase of the carbon dioxide conversion and a decrease of coke formation. 

In addition to water, certain other additives have been noted to have a marked effect on the pyrolysis of coal. Materials such as zinc chloride (ZnCl2), aluminum chloride (AICI3), sodium hydroxide (NaOH), iron oxide (Fe203), phosphoric acid (H3PO4), clay (aluminosilicate minerals), and active carbon bring about a significant decrease in the amount of coke produced and, with the exception of the phosphoric acid and the carbon, increase the yields of the gases. 

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