Life Cycle Assessment of Nitrogen Circular Economy-Based NOx Treatment Technology

Abstract

Humans are significantly perturbing the global nitrogen cycle, leading to excess reactive nitrogen in the environment. Nitrogen oxides as a key reactive nitrogen species are mainly controlled by selective non-catalytic reduction and selective catalytic reduction. Converting nitrogen oxides to ammonia, defined as ReNOx, emerges as an alternative method under a disparate design concept. However, little is known about its overall environmental performance. In this study, we conducted for the first time a life cycle assessment of ReNOx. Compared with the eco-index in the condition of 200 °C with a conversion rate of 95%, it would increase substantially in the condition of 160 °C with a conversion rate of 80% and in the case without a sound NH3 treatment. Feedstock format change, adsorption material performance deterioration, and recovery rate decline would increase the eco-index by 8%, 12%, and 18%, respectively. The eco-index was decreased by 31% in the optimized scenario with a renewable energy source and an increased conversion rate. The environmental impacts were compared with traditional methods at impact, damage, and eco-index levels. Finally, the implications on process arrangement in the flue gas system, the externality for power generation, and the contribution to the nitrogen circular economy were examined. The results can serve as a reference for its developers to improve the technology from the environmental perspective.

Modeling Ground Ozone Concentration Changes after Variations in Precursor Emissions and Assessing Their Benefits in the Kanto Region of Japan

“…Another promising technology considers reducing NO into ammonia (NH 3 ), a compound widely used as a fertilizer and potential source of energy. Although this technology is still under development and a detailed plan for its implementation is still under consideration, reduction efficiencies of 50% have been reported [49,50].…”

Effect of TiO2 Drying Conditions on the Catalytic Activity of Pt for Ammonia Synthesis from NO−H2

“…[5] A new concept was introduced in recent years which involved selective conversion of NO to ammonia (NTA) [6,7] and designated as ReNOx. [8] Supported Pt or Pd catalysts have been reported for NTA reaction using COÀ H 2 O reductant. [9][10][11][12] Recently, our group also developed Pt/TiO 2 catalyst for ammonia formation from NOÀ COÀ H 2 O reaction.…”

“…Nitrogen oxides (NO x ) emission by stationary and mobile sources lead to various environmental problems such as acid rain and photochemical smog [5] . A new concept was introduced in recent years which involved selective conversion of NO to ammonia (NTA) [6,7] and designated as ReNOx [8] . Supported Pt or Pd catalysts have been reported for NTA reaction using CO−H 2 O reductant [9–12] .…”

Ammonia formation by reduction of nitrogen monoxide with carbon monoxide using copper-deposited ceria in the presence of water

“…We have proposed that NO x should be converted to valuable material instead of low-value N 2 production if substantial energy is required to detoxify it. 3,4…”

“…We have proposed that NO x should be converted to valuable material instead of low-value N 2 production if substantial energy is required to detoxify it. 3,4 In our previous work, we reported that titanium dioxidesupported Pt catalysts exhibit relatively high activity for the NO to NH 3 reaction, and we have proposed an exhaust gas treatment process that takes advantage of this reaction. 4,5 The reaction itself, in which NH 3 is formed from NO, has been well known.…”