Electron beam treatment of high NOx concentration off-gases

Electron beam flue gas technology for SOx and NOx simultaneous removal: its process and chemistry evolution from power plants to diesel off-gas treatment

Environmental pollution is one of the most important problems in present-day society. Governments and international organizations try to mitigate this problem by enforcing strict laws concerning the emission of certain pollutants. This process is especially rapidly applied concerning air pollution. In the past, the main focus was placed on the regulation of the energy sector and of land-based transportation emissions, as they produce the vast majority of pollutants. Today, the emphasis is shifted toward marine-based transportation, as it is anticipated that after the year 2020, the emission from sea-based sources (with respect to sulfur and nitrogen oxides) will exceed the land-based emission. One of the technologies that have been successfully implemented in industries to decrease the level of air pollution caused by NOx and SOx is electron beam flue gas treatment. This review shows the chemical principles of this method as well as the chemical engineering issues and its development and modifications to suit the changing needs of industries worldwide.

Technologies for the nitrogen oxides reduction from flue gas: A review

The required energy of the global industry is mostly generated from fossil fuel sources, such as natural gas, gasoline, diesel, oil, and coal. Nitrogen oxides are one of the main air pollutants that are produced from the combustion of fossil fuels in stationary and mobile sources. Development of new technologies to decrease the NO_x emission from exhaust gases is essential due to the harmful effect of NO_x on the environment and human health. Compared with pre-combustion and combustion methods (with <50% NO_x removal efficiency), the post-combustion methods with higher efficiency (above 80%) have attracted more attention in NO_x elimination. This review describes the currently used technologies of NO_x abatement. Different available post-combustion methods of NO_x removal, including selective catalytic reduction (using different types of reducing reagents, including ammonia, hydrogen, hydrocarbons, and carbon monoxide), selective noncatalytic reduction, wet scrubbing, adsorption, electron beam, nonthermal plasma, and electrochemical reduction of NO_x, are discussed.

Radical-induced oxidation removal of multi-air-pollutant: A critical review

Sulfur dioxide (SO₂), nitric oxide (NO) and elemental mercury (Hg⁰) are three common air pollutants in flue gas. SO₂ and NO are the main precursors for chemical smog and Hg⁰ is a bio-toxicant for human. Cooperative removal of multi-air-pollutant in flue gas using radical-induced oxidation reaction is considered as one of the most promising methods due to the high removal efficiency, low cost and less secondary environmental impact. The common radicals used in air pollution control can be classified into four types: (1) hydroxyl radical (OH), (2) sulfate radical (SO₄^-), (3) chlorine-containing radicals (Cl, ClO₂, ClO, HOCl^-, etc.) and (4) ozone. This review summarizes the generation methods and mechanism of the four kinds of radicals, as well as their applications in the removal of multi-air-pollutant in flue gas. The reactivity, selectivity and reaction mechanism of the four kinds of radicals in multi-air-pollutant removal were comprehensively described. Finally, some future research suggestions on the development of new technique for cooperative removal of multi-air-pollutant in flue gas were provided.