Chromium based oxides acid-base properties

This work is devoted to the synthesis of Zr02 by various methods, the synthesis of zirconium-containing pentasils and Zr02 - -zeolite based binary carriers. These materials were used as carriers of transition metal oxides (chromium, cobalt) and their catalytic properties were characterized in the selective reduction of NO by methane and propane-butane mixture, the acidic properties of the samples were investigated by thermoprogrammed desorption and IR-spectroscopy methods. 

The three common chromium oxides are CrO, Cr203, and Ci<)3. If Cr203 is amphoteric, what can you say about the acid-base properties of CrO and C1O3 ... 

CHEMICAL PROPERTIES Chemical properties vary depending upon the specific soluble or insoluble molybdenum compound. Molybdenum is fairly stable at ordinary temperatures less reactive than chromium (Cr) to acids combines with oxygen to give the trioxide (M0O3) at red heat slowly oxidized by steam reacts with hot concentrated sulfuric acid, nitric acid, fused potassium chlorate or nitrate at ordinary temperatures, attacked by fluorine attacked by chlorine or bromine at very high temperatures Molybdenum trioxide readily forms s a series of polymeric compounds on combination with acids or bases sublimes at higher temperatures, starting at 700°C (1292°F) reported to be photosensitve forms molyb-... 

Numerous nickel alloys, in particular those based on copper, chromium, or iron, have both good mechanical properties and high corrosion resistance (Table 12.9). Copper, in particular, improves the resistance against oxidizing acids, while molybdenum improves the resistance towards non-oxidizing acids and chloride-containing environments. Highly corrosion resistant nickel alloys, especially those... 

CHEMICAL PROPERTIES strong oxidizer reacts with water to produce heat corrosive in presence of traces of oxides attacks all base metals except aluminum and special chromium steels reacts vigorously with combustibles, organic solvents, metallic powders, carbides, cyanides, sulfides, or readily oxidizable materials reacts with alkalies vigorous reaction caused by addition of water to concentrated nitric acid FP (NA) LFL/UFL (not combustible) AT (NA) HC (NA) HF (-174.1 kJ/mol liquid at 25°C) Hf (2.503 kcal/mol) HID (-7971 cal/mol at 25°C). 

Notably, catalysts with redox properties, such as molybdenum-, chromium-, and vanadia-based catalysts, show high activity in various oxidative dehydrogenation reactions of hydrocarbons [45 8]. Factors influencing the reaction also include acid-base bifunctionality, which plays an important role in CO2-mediated dehydrogenation reactions [49]. Both basic sites and Lewis-acid vacant sites are important for hydrocarbons activation [50]. In fact, an enhanced basicity results in an improved performance because of the rapid desorption of the electron-rich alkenes, whereas Lewis acid sites enhance the dehydrogenation process [51]. In addition, in the presence of CO2 as feed, surface basicity favors the adsorption and reactivity of the acid CO2 molecules [52] (see also previous chapters). 

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