Ammonium metavanadate (NH4VO3) is an inorganic compound that can act as an environmental catalyst in various applications. It contains the vanadium(V) cation, which is a redox-active element with multiple oxidation states, allowing it to participate in catalytic reactions.

Here are a few ways in which ammonium metavanadate can function as an environmental catalyst:

1. Air Pollution Control: Ammonium metavanadate can be used as a catalyst in selective catalytic reduction (SCR) systems to mitigate nitrogen oxide (NOx) emissions from industrial processes and power plants. In SCR, ammonia (NH3) is used as a reducing agent to convert harmful NOx into nitrogen (N2) and water (H2O) through a reaction facilitated by the catalyst.

2. Organic Synthesis: Ammonium metavanadate can serve as a catalyst in various organic synthesis reactions. For instance, it can be used in the oxidative bromination of organic compounds, where it facilitates the introduction of bromine atoms into specific positions of a molecule. It can also catalyze oxidation reactions, such as the conversion of alcohols to aldehydes or ketones.

3. Water Treatment: Ammonium metavanadate has been investigated for its potential in water treatment applications. It can act as a catalyst in advanced oxidation processes (AOPs) to degrade organic pollutants in water. AOPs typically involve the generation of highly reactive hydroxyl radicals (•OH), which can break down organic contaminants into simpler, less harmful compounds. Ammonium metavanadate can participate in these reactions and enhance the degradation efficiency.

4. Fuel Cells: Vanadium-based compounds, including ammonium metavanadate, have been explored as catalysts in fuel cells. Fuel cells generate electricity through electrochemical reactions, and catalysts are essential to facilitate these reactions. Ammonium metavanadate can be utilized as a catalyst in the oxygen reduction reaction (ORR) that occurs at the cathode of fuel cells, improving their efficiency and performance.