Systems and methods for producing nitrates, nitric acid, salts thereof, or a mixture thereof are disclosed. The systems may include a feed conduit configured for receiving a feed stream comprising molecular oxygen and molecular nitrogen; an inlet conduit configured for receiving an inlet stream; a plasma reactor fluidically coupled to the inlet conduit, the plasma reactor fluidically coupled to a reactor-outlet conduit configured for receiving the reactor-outlet stream, the plasma reactor configured to produce oxidized nitrogen species; and an absorber fluidically coupled to the reactor-outlet conduit, the absorber configured to receive the reactor outlet stream and to produce nitrates, nitrites, nitric acid, salts thereof, or a mixture thereof from the reactor outlet stream. A recycle conduit may be fluidically coupled to the absorber and the inlet conduit, wherein the recycle conduit is configured to receive the gas-phase stream from the absorber and provide the gas-phase stream to the inlet conduit.

A gas purification device includes: a converter packed with a catalyst for hydrolyzing both carbonyl sulfide and hydrogen cyanide; an upstream heat exchanger for heat exchange between a gas to be introduced into the converter and a cooling fluid for cooling the gas; a reaction-temperature estimation member for estimating a reaction temperature inside the converter; and a flow-rate adjustment member for adjusting a flow rate of the cooling fluid flowing into the upstream heat exchanger based on an estimated value of the reaction-temperature estimation member to control the reaction temperature.

An ionic oxidation refreshing system for refreshing odorized items, comprising an enclosure to contact the odorized items; an ionizing stage mechanism that produces an ionized ozone gas mixture inside of the enclosure, killing germs, including odor-causing bacteria, viruses, molds, and fungus; and a filtering stage mechanism that neutralizes and filters out any toxic by-products including one or more of ozone, nitric acid, aldehydes, and VOCs resulting from surface oxidation of the odorized items by the ionized ozone gas mixture.

An ionic oxidation refreshing system for refreshing odorized items, comprising an enclosure to contact the odorized items; an ionizing stage mechanism that produces an ionized ozone gas mixture inside of the enclosure, killing germs, including odor-causing bacteria, viruses, molds, and fungus; and a filtering stage mechanism that neutralizes and filters out any toxic by-products including one or more of ozone, nitric acid, aldehydes, and VOCs resulting from surface oxidation of the odorized items by the ionized ozone gas mixture.

The present invention discloses a method of preparing a catalyst for low-temperature synergistic catalytic purification of NO.sub.x and HCN in a flue gas, and the use thereof. Citric acid is dissolved in ethanol to obtain a citric acid/ethanol solution; tetrabutyl titanate is added, mixed uniformly to obtain a tetrabutyl titanate-citric acid/ethanol solution; glacial acetic acid is added dropwise to react for 30-40 min to obtain a solution A; the metal salt solution was added dropwise into the solution A, mixed uniformly and added with nitric acid, ammonium hydroxide is added dropwise to adjust the pH value and the temperature is raised at a constant speed to obtain a gel B; dried and then then baked at a temperature of 300-500 C. for 3-4 h, cooled in the furnace, pulverized, tableted and sieved to obtain the catalyst for the low-temperature synergistic catalytic purification of NO.sub.x and HCN in the flue gas.

A used denitration catalyst is regenerated by means of a method comprising bringing the used denitration catalyst comprising titanium oxide as an essential ingredient into contact with a suspension of particles comprising manganese oxide, subjecting the resulting product to a liquid draining, and subjecting the liquid-drained product to a drying process, additionally, further comprising impregnating a solution comprising a compound containing at least one element selected from the group consisting of vanadium, molybdenum and tungsten into the denitration catalyst after the drying process, and subjecting the impregnated product to a drying treatment.

A gas clean-up unit includes a first conversion unit configured to perform a first conversion process of converting hydrogen cyanide contained in gas to be treated to ammonia, in presence of a first catalyst and at a first predetermined temperature; a second conversion unit configured to perform a second conversion process of converting carbonyl sulfide in the gas that has been subjected to the first conversion process to hydrogen sulfide, in presence of a second catalyst and at a second predetermined temperature lower than the first predetermined temperature; a cleaning unit configured to perform a cleaning process of bringing the gas into gas-liquid contact with cleaning liquid to remove the ammonia by cleaning; and a desulfurization unit configured to absorb and remove hydrogen sulfide in the gas by bringing the gas that has been subjected to the cleaning process into gas-liquid contact with absorbent.

Systems and methods directed at removing HCN from an FCC process flue gas (and/or generated in the catalyst system reactions themselves) such that the final HCN output is satisfactory; while, in so doing, avoiding undesirable levels of other pollutants contained in that exhaust gas such as NOx. A system includes an assembly having a fluid catalytic cracking (FCC) unit generating a flue gas with HCN and NOx and a catalyst device placed in the flue gas line to remove HCN and NOx. The catalyst device having one or more SCR catalytic articles, as in one free of platinum group metal material (PGM) or a dual functioning SCR catalyst with PGM, or a combination of each. The assembly can be provided with an ammonia supplier and optionally an H2O supplier with associated injection for supply into the flue gas upstream of a catalytic article(s).

The present application is directed to a method for the conversion of nitrous acid to dinitrogen gas. In particular, the present application relates to a method for the conversion of nitrous acid to dinitrogen gas by contacting the nitrous acid with an amine-functionalized metal organic framework.

Provided herein is a device for removing residual hydrogen peroxide or hydrazine from an effluent gas stream which includes a metal oxide scrubber material configured to react with residual process gases under increased temperatures. Also provided are systems and methods of using the same.