Nitric Acid Plants Research Articles

The Behavior of Catalytic, Low-Temperature N2O Decomposition (LT-deN2O) in the Presence of Sulfur-Containing Compounds on Nitric Acid Plants

The Behavior of Catalytic, Low-Temperature N2O Decomposition (LT-deN2O) in the Presence of Sulfur-Containing Compounds on Nitric Acid Plants

Operating parameters analysis of a nitric acid plant to increase production and reduce NOx gases emission

In this work the influence of some operating parameters of a medium pressure nitric acid plant producing 54,000 t/year was studied in order to evaluate its influence over the absorption column efficiency. The target is to increase nitric acid production and reduce NOx emissions. The nitric acid plant was simulated using ProSimPlus HNO3. The parameters considered in the analyses were: secondary air molar flow rate; absorption column operating pressure; cooling water temperature and absorption water molar flow rate. Parameters were evaluated individually and the best results were combined in a multi-parameter analysis evaluating different optimized scenarios, including the possibility of increasing the amount of ammonia injected in the system and the addition of a plug flow reactor (PFR), which is a new approach to improve NO oxidation. Considering a base case, the best scenario obtained was able to reduce NOx emissions in 55 % while increasing nitric acid production in 18 %, using the following set of parameters: 20 kmol.h − 1 of additional ammonia; a 40 m3 PFR; cooling water at 5 °C; 172 kmol.h − 1 of absorption water and 345 kmol.h − 1 of secondary air. The results obtained in this work contribute to provide practical insights for optimum absorption stage operation in a real nitric acid plant.

Exploiting synergies between sustainable ammonia and nitric acid production: A techno-economic assessment

The decarbonization of the fertilizer industry is an important step towards a climate-neutral society. Nitric acid produced via the Ostwald process is a key precursor to nitrogen-based fertilizers, with the production of ammonia representing an important intermediate step. This work focuses on the search for synergies between the sustainable production of ammonia feedstocks – hydrogen and nitrogen – and nitric acid production in the Ostwald process: Oxygen a by-product of sustainable hydrogen and nitrogen production was considered for injection in the Ostwald process at 4 points. A techno-economic assessment was performed to identify the technical and economic potential of this air enrichment. In addition, the safety implications of applying a higher oxygen concentration in the ammonia combustion step of the Ostwald process was evaluated based on explosion limit simulations. The techno-economic assessment was based on a mono-pressure nitric acid plant with a plant capacity of 700t/d of pure nitric acid at a concentration of 60wt% in water. The investigations of injecting oxygen at four different points of the plant show that daily nitric acid production can be increased by 0.31% and final NOx concentration of the absorption column can be reduced by up to 43.6% by enriching the main air pipeline with oxygen. Optimal oxygen injection could reduce the capital costs by 0.41M€. Nevertheless, the operating costs dominated the final cash flow analysis with ammonia costs accounting for ca. 60% of the total operating costs. The CO2 price would need to increase to at least 233€/t to compensate for the higher green ammonia price and equalize the minimum selling price. As the oxygen injection at the main air line comes with safety risks due to the ammonia explosion limits, we evaluated the effect of O2-enrichment on the explosion limits of NH3-O2-N2 mixtures. The foreseen oxygen enrichment reduced the lower explosion limit only marginally. For a medium pressure plant at 5.8bar the lower explosion limit is reduced to 10.3% for the highest considered oxygen injection case, which is close to the applied ammonia concentration.

Boosting N2O Decomposition by Fabricating the Cs-O-Co Structure over Co3O4 with Single-Layer Atoms of Cs.

Developing effective catalysts for N2O decomposition at low temperatures is challenging. Herein, the Cs-O-Co structure, as the active species fabricated by single-layer atoms of Cs over pure Co3O4, originally exhibited great catalytic activity of N2O decomposition in simulated vehicle exhaust and flue gas from nitric acid plants. A similar catalytic performance was also observed for Na, K, and Rb alkali metals over Co3O4 catalysts for N2O decomposition, illustrating the prevalence of alkali-metal-promotion over Co3O4 in practical applications. The catalytic results indicated that the TOF of Co3O4 catalysts loaded by 4 wt% Cs was nearly 2 orders of magnitude higher than that of pure Co3O4 catalysts at 300 °C. Interestingly, the conversions of N2O decomposition over Co3O4 catalysts doped by the same Cs loadings were significantly inhibited. Characterization results indicated that the primary active Cs-O-Co structure was formed by highly orbital hybridization between the Cs 6s and the O 2p orbital over the supported Co3O4 catalysts, where Cs could donate electrons to Co3+ and produce much more Co2+. In contrast, the doped Co3O4 catalysts were dominated by Cs2O2 species; meanwhile, CsOH species was generated by adsorbed water vapor led to a significant decrease in catalytic activity. In situ DRIFTS, rigorous kinetics, and DFT results elaborated the reaction mechanism of N2O decomposition, where the direct decomposition of adsorbed N2O was the kinetically relevant step over supported catalysts in the absence of O2. Meanwhile, the assistance of adsorbed N2O decomposition by activated oxygen was observed as the kinetically relevant step in the presence of O2. The results may pave a promising path toward developing alkali-metal-promotion catalysts for efficient N2O decomposition.

Thermal-hydraulic characteristics of nitric acid: An experimental and numerical analysis

Nitric acid is one of the most important products in the chemical industry, ranking third globally in terms of acid production. Although nitric acid has many industrial applications, its primary function is the production of ammonium nitrate, which is used in the fertilizer industry. In this report, we propose a plan for an Ostwald process plant that will produce 1000 metric tons of nitric acid per day. Based on an effective energy analysis, we have concluded that using a single pressure method provides optimal results. First, ammonia is vaporized using process heat at 1000 kPa and 35 °C before being superheated using steam to a temperature of 80 °C. Filtered air is compressed by an axial compressor to a discharge pressure of approximately 740 kPa and a temperature of 155 °C. After conducting a site evaluation, three existing manufacturing sites are being considered for the acid production plant: Ogun State (Nigeria), Gwadar Seaport (Pakistan), and Ras-Alkhair Seaport (Saudi Arabia). Based on the results of the site assessment, Ras-Alkhair has been selected as the most suitable location for the nitric acid plant. About 65 % of all nitric acid produced worldwide is used in the production of ammonium nitrate, which is in turn used in the fertilizer and explosives industries. The synthetic nitric acid that will be produced from this plant will be used in the production of fertilizers.

Redox transformations of Ru catalyst during NO oxidation at industrial nitric acid production conditions

Oxidation of nitric oxide is one of the main steps in the Ostwald process for industrial nitric acid production. This work summarises the use of γ-Al2O3 supported Ru catalyst to study the oxidation of NO to NO2 at ambient and 4 bar pressure with a feed of 10% NO, 6% O2, 15% H2O, and rest Ar. The catalyst was synthesised using wet impregnation and characterised by BET, CO chemisorption, H2-TPR, XPS, XRD, in-situ XAS-XRD and DRIFTS. We report the activity and kinetics of supported ruthenium catalyst for NO oxidation under realistic nitric acid plant conditions. The catalyst exhibited a promising low-temperature activity of 72% at 340 °C in complete nitric acid condition and 37% at 420 °C in partial nitric acid condition. An apparent activation energy of 152 kJ/mol was observed and the overall rate was determined to be r =kf.KG.PNO2.PO2PNO2, where kf and KG represents forward rate and equilibrium rate constants respectively. The reaction was found to be second order with respect to NO, first order with respect to O2 and inversely dependent on NO2 partial pressure. The stability of the catalyst was also tested during 45 h of isothermal NO oxidation at ambient pressure. From in-situ XAS-XRD and DRIFTS experiments it was revealed that during isothermal NO oxidation the reaction oscillates as the ruthenium surface goes through redox cycles. A plausible reaction mechanism that fits with our experimental observations and the oxidative nature of ruthenium is proposed. This study demonstrates and explains the capacity of supported ruthenium catalysts to oxidise NO to NO2 in industrial nitric acid production conditions.

Energy, exergy, and sustainability analysis of an industrial nitric acid plant

ABSTRACT In this paper, energy, exergy, and sustainability analyses are performed on the Karun petrochemical nitric acid plant in Mahshahr at varying ambient temperatures to reveal realistic optimization opportunities. All plant components have been analyzed individually by using mass, energy, and exergy balance equations. Results regarding energy, exergy, and sustainability evaluations of the equipment have been presented in the individual table. The energy analysis indicates that the system’s energy efficiency is 30.9% and introduces the absorber column as the equipment with the highest heat transfer to the environment in the entire plant (6889 kW). The exergy analysis revealed that the exergy efficiency of the entire system had variations ranging from 13.39% to 14.72%, which is inversely proportional to the increase in dead state temperatures. The maximum amount of exergy destruction is calculated for the converter (5129 kW at 45°C). In addition, exergy analysis identified the converter as the component with the most potential for improvement (2918 kW at 45°C). On the other hand, the highest sustainability index is found for the absorber column (1.616 at 15°C). Moreover, by selecting the optimal intermediate pressure for the compressors, the power consumption of the air compression system has been reduced by 185.9 kW, and its exergy efficiency has increased by 3%.

The Technology of Tail Gases Purifying in Nitric Acid Plants and Design of deN2O and deNOx Reactors—Review

The tightening standards of nitrogen oxides emission from industrial plants encourage nitric acid producers to search for new efficient solutions to meet the stringent emission limits. Industrial practice and the patent literature show that the effectiveness of deNOx (SCR) and deN2O technology is affected not only by the type and shape of the catalyst, but also by the method of its installation in a heterogenous catalytic reactor. The article presents the background of the problem, related to the emission of nitrogen oxides from nitric acid plants, and describes the technology of the tail gases purified from NOx and N2O. It shows various aspects that should be considered in designing reactors for deNOx and deN2O processes in nitric acid plants. The advantages and disadvantages of different catalytic basket designs, their industrial application and the direction of their design development were also indicated.

Modeling of a Two-Bed Reactor for Low-Temperature Removal of Nitrogen Oxides in Nitric Acid Production

In this study, the modeling of the low-temperature catalytic abatement of NOX and N2O from tail gases in a weak nitric acid plant utilizing a single-pressure 0.716 MPa system was performed. A one-reactor concept assumes that in the first bed, NOX is reduced by ammonia on a commercial vanadia–alumina catalyst, and in the second bed, N2O is decomposed on a proprietary nickel–cobalt catalyst. The kinetics of N2O decomposition on a Cs/Ni0.1Co2.9O4 catalyst was experimentally studied in an isothermal flow reactor. The reaction rate constants were determined by varying the residence time and temperature; these data formed the basis for modeling kinetics and heat and mass transport in an adiabatic reactor in which the low-temperature mitigation of nitrogen oxides occurred. Taking into account the given spatial limitations inside the reactor and the allowable temperatures, the layer heights were evaluated to ensure a residual NOX and N2O content of less than 50 ppm. Catalyst loading using layers in a commercial reactor was estimated for the tail-gas flow rates of 46,040–58,670 m3/h. Simulations showed that the optimum inlet temperature was 260 °C; in this case, the NOX and N2O conversion targets were achieved in the range of 46,040–58,670 m3/h while adhering to catalyst bed height and outlet temperature limitations.

The preparation of 3.0F-Co3O4 catalyst with “Yardang Landform” structure and its performance for catalyzing N2O decomposition

In this work, the 3.0F-Co3O4 catalyst was synthesized by sol-gel method with the assistance of F127 and used for eliminating the N2O pollution from nitric acid plants. Research indicated that the presence of F127 in the preparation process endowed the 3.0F-Co3O4 catalyst with unique “Yardang Landform” microstructure, which possessed a rich number of “edges and corners”. The unique microstructure enables the 3.0F-Co3O4 catalyst to mainly expose highly active (400) and (511) crystal planes. Based on this unique microstructure, the surface active site density for 3.0F-Co3O4 catalyst was 7.62 µmol g−1 m2, which was about 9 times that of Co3O4(CP) catalyst prepared by traditional co-precipitation method. In addition, the 3.0F-Co3O4 catalyst demonstrated high catalytic activity and stability for the reaction in presence of impurity gases. For example, the catalyst can maintain a conversion of more than 60% for N2O at least 10 h in the feed stream of 2000 ppmv N2O/Ar with 5 vol% O2, 100 ppmv NO and 2 vol% H2O at 400 °C and GHSV = 20,000 h−1.

Business Roundup

BUSINESS Business Roundup ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2023, 101 (3), p 15January 23, 2023Cite this:C&EN 101, 3, 15AbstractChemours has picked Villers-Saint-Paul, France, as the site for a $200 million capacity expansion of its Nafion ion-exchange materials, used in water electrolyzers that produce hydrogen. The firm said last fall that it was considering sites in the US and Europe. Orica and Saudi Chemical will work together to build nitric acid and ammonium nitrate plants in Saudi Arabia. Saudi Chemical says the planned facility will be the first of its kind in the region. Novozymes has entered a partnership to supply enzymes to Carbios, which has developed an enzymatic process to break down polyethylene terephthalate into its raw materials, terephthalic acid and ethylene glycol. Carbios’s first commercial-scale plant using its technology is set to open in France in 2025. PureCycle Technologies has selected the Port of Antwerp-Bruges as the location of the first European plant to use its solvent-based process to recycle polypropylene. The company’s first plant is underView: PDF | Full Text HTML

N2O Catalytic Decomposition and NH3-SCR Coupling Reactions over Fe-SSZ-13 Catalyst: Mechanisms and Interactions Unraveling via Experiments and DFT Calculations

Simultaneous catalytic elimination of NO and N2O from exhausts is an ideal solution for nitric or adipic acid plants. Herein, Fe-based zeolite catalysts were applied for the NH3–NOx–N2O system. 1% Fe-SSZ-13 performed excellent catalytic activity with 100% conversions for both NOx and N2O at 400–600 °C. Experimental and computational research studies unraveled that NO could significantly improve N2O decomposition by reacting with αO* to generate easily desorbed NO2; furthermore, NO−αO* also can decrease charge density of Fe−αO*, facilitating αO* desorbed from the Fe sites. Besides, NH3 inhibits low-temperature deN2O activity due to strong competitive adsorption with N2O; however, NH3 accelerates N2O decomposition by consuming αO* and simultaneously reduces N2O as a reductant at high temperature. Interestingly, the αO* generated from N2O decomposition would enhance NO oxidation to NO2, which is beneficial to NH3-selective catalytic reduction. This work elaborates fundamental insights for simultaneous abatement of NOx and N2O and provides candidate catalyst for application.

Sm doped NiO catalysts with excellent H2O resistance for N2O decomposition under simulated nitric acid plant exhaust condition

Sm0.06Ni with excellent H2O resistance for eliminating N2O was prepared by co-precipitation method. Research indicated that the introduction of Sm into Sm0.06Ni has the following effects: (1) Sm species (Sm2O3) highly dispersed on the surface of Sm0.06Ni catalyst, which not only decreased the crystallite size of NiO, but also produced a certain number of edge dislocations and defects. (2) Sm2O3 weakened the Ni-O band and increased the number of active sites. (3) The redox cycle of Ni2+ + Sm3+ ↔ Ni3+ + Sm2+ was formed on the surface of Sm0.06Ni during the reaction. Based on the above changes, Sm0.06Ni exhibited superior catalytic performance and much lower Ea for the reaction compared with pure NiO. Over Sm0.06Ni, the TOF at 350 ℃ was 4.1 × 10−3 s−1, 37 times of that over pure NiO. More importantly, Sm0.06Ni exhibited excellent H2O resistance performance under submitted real reaction conditions, about 76 % N2O conversion can be obtained at 400 ℃.

Physicochemical Features and NH3-SCR Catalytic Performance of Natural Zeolite Modified with Iron—The Effect of Fe Loading

In modern dual-pressure nitric acid plants, the tail gas temperature usually exceeds 300 °C. The NH3-SCR catalyst used in this temperature range must be resistant to thermal deactivation, so commercial vanadium-based systems, such as V2O5-WO3 (MoO3)-TiO2, are most commonly used. However, selectivity of this material significantly decreases above 350 °C due to the increase in the rate of side reactions, such as oxidation of ammonia to NO and formation of N2O. Moreover, vanadium compounds are toxic for the environment. Thus, management of the used catalyst is complicated. One of the alternatives to commercial V2O5-TiO2 catalysts are natural zeolites. These materials are abundant in the environment and are thus relatively cheap and easily accessible. Therefore, the aim of the study was to design a novel iron-modified zeolite catalyst for the reduction of NOx emission from dual-pressure nitric acid plants via NH3-SCR. The aim of the study was to determine the influence of iron loading in the natural zeolite-supported catalyst on its catalytic performance in NOx conversion. The investigated support was firstly formed into pellets and then impregnated with various contents of Fe precursor. Physicochemical characteristics of the catalyst were determined by XRF, XRD, low-temperature N2 sorption, FT-IR, and UV–Vis. The catalytic performance of the catalyst formed into pellets was tested on a laboratory scale within the range of 250–450 °C using tail gases from a pilot nitric acid plant. The results of this study indicated that the presence of various iron species, including natural isolated Fe3+ and the introduced FexOy oligomers, contributed to efficient NOx reduction, especially in the high-temperature range, where the NOx conversion rate exceeded 90%.

Evaluation of the inhibiting effect of H2O, O2, and NO on the performance of laboratory and pilot K-ZnxCo3-xO4 catalysts supported on α-Al2O3 for low-temperature N2O decomposition

The K-ZnxCo3-xO4 catalyst supported on α-Al2O3 for N2O decomposition was investigated in terms of its resistance towards typical contaminants (O2, H2O, and NO) present in the nitric acid plant tail gases. The catalyst synthesized in laboratory-scale was thoroughly characterized by means of X-ray μ-tomography, XRF, XRD, and SEM/TEM/EDX. The impact of contaminants such as O2, H2O, and NO on the N2O conversion of the catalyst was examined and quantified by kinetic and thermodynamic modeling. The mechanism of inhibition involving local (active site blocking) and global (modification of the spinel electronic properties by electrophilic NOx adspecies) effects was proposed. The strongest inhibition of NO was associated with its facile reactivity with surface O intermediates produced during N2O decomposition. The resultant NO2 and NO3 surface adducts are stable at the catalyst surface up to 550 °C. For the pilot catalyst, the effect of contamination was the same in nature as for the laboratory sample, however, the observed quantitative differences were associated with the changes in the shape of the spinel nanocrystals constituting the catalyst active phase. The obtained results provide rationales for designing and preparation of the robust deN2O catalyst with enhanced resistivity to poisoning.

Modified Zeolite Catalyst for a NOx Selective Catalytic Reduction Process in Nitric Acid Plants

Natural zeolite of the heulandite-type framework was modified with iron and tested as a catalyst for the selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR) in the temperature range of 150–450 °C. The catalyst was prepared at a laboratory scale in a powder form and then the series of experiments of its shaping into tablets was conducted. Physicochemical studies of the catalyst (N2 sorption at −196 °C, FT-IR, XRD, UV-vis) were performed to determine the textural and structural properties and identify the surface functional groups, the crystalline structure of the catalysts and the form and aggregation of the active phase. The activity tests over the shaped catalyst were performed industry-reflecting conditions, using tail gases from the pilot nitric acid plant. The influence of a temperature, catalyst load, and the amount of reducing agent (ammonia) on the NOx reduction process were investigated. The results of catalytic tests that were performed on model gas mixture showed that non-modified clinoptilolite exhibited around 58% conversion of NO at 450 °C. The temperature window of the shaped catalyst shifted to a higher temperature range in comparison to the powder sample. The catalytic performance of the shaped Fe-clinoptilolite in the industry-reflecting conditions was satisfactory, especially at 450 °C. Additionally, it was observed that the ratio of N2O concentration downstream and upstream of the catalytic bed was below 1, which indicated that the catalyst exhibited activity in both DeNOx and DeN2O process.

Haldor Topsoe's catalyst reduces emissions from new nitric acid plant in Greece

Sclerochronology is a method used to estimate the season of death (season of capture) of archaeological individuals based on a modern growth model. This method has been increasingly accepted in South America and has mainly been applied to coastal archaeological sites (on the Atlantic and Pacific Oceans). This is the first time that this method has been applied to a freshwater species, the marbled swamp eel (Synbranchus marmoratus), in archaeology. Excavations undertaken at Loma Salvatierra, a human-built platform located in the Bolivian Amazon and occupied from 500 until 1400 CE, have yielded 111 zooarchaeological vertebrae of the marbled swamp eel, which is one of the most widely distributed species recovered in South American continental archaeological sites. In order to estimate the fishing season for these archaeological individuals, we developed a modern osteological reference collection, made up of 61 specimens with known capture dates sampled monthly over a one-year period, about 60 km from Loma Salvatierra. The vertebrae present periodic growth patterns with a succession of dark and light bands alternately. Consequently, the vertebrae are a reliable basis for the estimation of the marbled swamp eel fishing season. The analysis of the marginal increments of vertebrae in present-day fish allowed us to elaborate a modern growth model showing that the seasonal growth of the marbled swamp eel is related to the hydrological cycle, whereby the fast growth period coincides with the onset of rainfall in the region. On the basis of this modern-based model, the analysis of zooarchaeological vertebrae demonstrates that fish were captured over several seasons. Demonstrating that human groups occupied villages year-round does not mean that they were not mobile but shows year-round fishing in the savanna. This year-round fishing practice raises questions concerning the generalized idea of fishing as an exclusively dry-season activity. As wild resources are generally seasonal, the evidence of the year-round fishing of swamp eels might suggest year-round fishing at Loma Salvatierra and contributes to the understanding of late-Holocene mobility patterns in pre-Columbian times.

Environmental quality and output volatility: the case of South Asian economies.

This study explores the impact of environmental degradation on output volatility for eight South Asian economies over the time span 1971-2017. Environmental degradation is measured by CO2 emissions, nitrous oxide (N2O), methane emissions (CH4), greenhouse gas emissions (GHG), and environmental pollutants index (EPI), whereas output volatility is constructed using a rolling window of five-year moving standard deviation. The results of cross-sectional dependence (CSD) tests indicate the presence of CSD among South Asian economies. For empirical analysis, second-generation panel time series approaches are employed. Also, the findings of panel unit root tests (URTs) signify that the variables are stationary at the first difference and have a long-run relationship. Westerlund cointegration test is used to assess the long-run relationship among the variables. Moreover, this study has used a fully modified ordinary least square (FMOLS) and dynamic modified ordinary least square (DOLS) methods to examine the relationship between environmental degradation and output volatility. In the long run, all indicators of environmental degradation are positive and significant signaling the harmful effects of environmental degradation on output volatility. However, the impact of nitrous oxide is larger relative to other indicators used in the study. The outcome, therefore, suggests that promoting clean investment in nitric acid plants might help improve the environmental quality in the region which in turn fosters the process of economic stability.

Design and Simulation of IoT Systems Using the Cisco Packet Tracer

Design and implementation of Internet of Things (IoT) systems require platforms with smart things and components. Two dominant architectural approaches for developing IoT systems are mashup-based and model-based approaches. Mashup approaches use existing services and are mainly suitable for less critical, personalized applications. Web development tools are widely used in mashup approaches. Model-based techniques describe a system on a higher level of abstraction, resulting in very expressive modelling of systems. The article uses Cisco packet tracer 7.2 version, which consists of four subcategories of smart things—home, smart city, industrial and power grid, to design an IoT based control system for a fertilizer manufacturing plant. The packet tracer also consists of boards—microcontrollers (MCU-PT), and single boarded computers (SBC-PT), as well as actuators and sensors. The model facilitates flexible communication opportunities among things—machines, databases, and Human Machine Interfaces (HMIs). Implementation of the IoT system brings finer process control as the operating conditions are monitored online and are broadcasted to all stakeholders in real-time for quicker action on deviations. The model developed focuses on three process plants; steam raising, nitric acid, and ammonium nitrate plants. Key process parameters are saturated steam temperature, fuel flowrates, CO and SOx emissions, converter head temperature, NOx emissions, neutralisation temperature, solution temperature, and evaporator steam pressure. The parameters need to be monitored in order to ensure quality, safety, and efficiency. Through the Cisco packet tracer platform, a use case, physical layout, network layout, IoT layout, configuration, and simulation interface were developed.

Two-Stage Catalytic Abatement of N2O Emission in Nitric Acid Plants

Different variants for abatement of N2O emission from nitric acid plants with the use of catalysts developed at Łukasiewicz-INS were analyzed. Activity tests on a pilot scale confirmed the high activity of the studied catalysts. A two-stage catalytic abatement of N2O emission in nitric acid plants was proposed: by high-temperature decomposition in the nitrous gases stream (HT-deN2O) and low-temperature decomposition in the tail gas stream (LT-deN2O). The selection of the optimal variant for abatement of N2O emission depends on the individual characteristics of the nitric acid plant: ammonia oxidation parameters, construction of ammonia oxidation reactor and temperature of the tail gas upstream of the expansion turbine. It was shown that the combination of both deN2O technologies, taking into account their technological constraints (dimensions of the catalyst bed), allows for a greater abatement of N2O emission, than the use of only one technology. This solution may be economically advantageous regarding the high prices of CO2 emission allowances.