Amount Of NOx Research Articles

Analysis of the National Air Pollutant Emissions Inventory (CAPSS 2018) Data and Assessment of Emissions Based on Air Quality Modeling in the Republic of Korea

According to the 2018 National Air Pollutant Emissions Inventory (NEI), air pollutant emissions in the Republic of Korea comprised 808,801 tons of CO, 1,153,265 tons of NOX, 300,979 tons of SOX, 617,481 tons of TSP, 232,993 tons of PM10, 98,388 tons of PM2.5, 15,562 tons of black carbon (BC), 1,035,636 tons of VOCs, and 315,975 tons of NH3. As for national emission contributions to primary PM2.5 and PM precursors (NOX, SOX, VOCs, and NH3), major source categories were the road sector for NOX, the industry sector for SOX and PM2.5, and the everyday activities and others sector for VOCs and NH3. In the case of emissions by region, the largest amount of NOX was emitted from the Seoul Metropolitan Areas (SMA; Seoul, Incheon, and Gyeonggi-do, hereafter SMA) and the largest amounts of SOX, PM2.5, VOCs, and NH3 were from the Yeongnam region. A 3D chemical transport modeling system was used to examine the uncertainty of the national air pollutant emissions based on the National Emission and Air Quality Assessment System (NEAS). Air quality was simulated using CAPSS 2018, and the simulation data were compared with observed concentrations to examine the uncertainties of the current emissions. These data show that emissions from five si (cities) (Pohang, Yeosu, Gwangyang, Dangjin, and Ulsan) need to be improved. Most of all, it is necessary to examine the emissions from places of business that use anthracite, which is the major PM2.5 emission source, as fuel in these areas.

Esterificación de ácido oleico para obtener biodiesel y utilizarlo como combustible en un motor a diésel para determinar su impacto

In this study, experimentally obtained biodiesel was analyzed as an alternative source of energy from oleic acid, using pure methanol and a solid acid catalyst in an autogenous reactor, the main product obtained was biodiesel, achieving a yield of 96.72 percent and thus demonstrating a greater conversion of free fatty acids (FFA) to methyl esters, allowing them to be studied in a diesel engine. Sulfonation of vulcanized rubber carbon produced the solid acid catalyst. Three control variables were used in the engine for the realization and analysis of the biodiesel obtained vs. commercial diesel in the internal combustion engine. Pure commercial diesel (PDI), biodiesel-diesel blend (50/50), and pure biodiesel (MES). The combustion tests show that there is no significant variation in the characteristics and performance of said tests; however, in the gaseous combustion products, significant reductions in carbon monoxide, unburned hydrocarbon, and an increase in greenhouse gas emissions were achieved. The greenhouse effect. nitrogen oxide when using the (PDI) versus the (MES). When MES and PBM were tested in a laboratory engine, the amount of NOx, CO, HC, and smoke emissions were reduced.

ENSURING THE ENVIRONMENTAL FRIENDLINESS OF MARINE DIESEL ENGINES OF SPECIALIZED SHIPS

Marine diesel engines (as the main component of a marine power plant) are sources of environmental pollution with exhaust gases, which include toxic components: carbon dioxide CO, hydrocarbons CnHm, soot C, sulfur oxides SOX, nitrogen oxides NOX [1-3]. Nitrogen oxides NOX occupy the first place among harmful emissions in almost all operating modes of diesel engines, regardless of their type, size and design features. Emission of nitrogen oxides with exhaust gases marine diesel engines is regulated by the requirements of Annex VI MARPOL. In accordance with the Tier-I, Tier-II, Tier-III standards (which apply to diesel engines of ships built after 2000, 2011 and 2016), the maximum amount of NOX in exhaust gases should not exceed the values determined by special expressions

Numerical Study on Hydrogen–Gasoline Dual-Fuel Spark Ignition Engine

Hydrogen, as a suitable and clean energy carrier, has been long considered a primary fuel or in combination with other conventional fuels such as gasoline and diesel. Since the density of hydrogen is very low, in port fuel-injection configuration, the engine’s volumetric efficiency reduces due to the replacement of hydrogen by intake air. Therefore, hydrogen direct in-cylinder injection (injection after the intake valve closes) can be a suitable solution for hydrogen utilization in spark ignition (SI) engines. In this study, the effects of hydrogen direct injection with different hydrogen energy shares (HES) on the performance and emissions characteristics of a gasoline port-injection SI engine are investigated based on reactive computational fluid dynamics. Three different injection timings of hydrogen together with five different HES are applied at low and full load on a hydrogen–gasoline dual-fuel SI engine. The results show that retarded hydrogen injection timing increases the concentration of hydrogen near the spark plug, resulting in areas with higher average temperatures, which led to NOX emission deterioration at −120 Crank angle degree After Top Dead Center (CAD aTDC) start of injection (SOI) compared to the other modes. At −120 CAD aTDC SOI for 50% HES, the amount of NOX was 26% higher than −140 CAD aTDC SOI. In the meanwhile, an advanced hydrogen injection timing formed a homogeneous mixture of hydrogen, which decreased the HC and soot concentration, so that −140 CAD aTDC SOI implied the lowest amount of HC and soot. Moreover, with the increase in the amount of HES, the concentrations of CO, CO2 and soot were reduced. Having the HES by 50% at −140 CAD aTDC SOI, the concentrations of particulate matter (PM), CO and CO2 were reduced by 96.3%, 90% and 46%, respectively. However, due to more complete combustion and an elevated combustion average temperature, the amount of NOX emission increased drastically.

Effects of piston shape and nozzle specifications on part-load operation of natural gas–diesel dual-fuel RCCI engine and its application to high load extension

• Effects of piston shape and multi-angle nozzle were evaluated for DF RCCI operation. • Enhanced air utilization w/multi-angle nozzle reduced combustion and HT losses. • The highest GIE of RCCI improved as 51.8 % by hardware modifications. • Intake air amount could be increased by lowering CR (from 17 to 15) at the maximum load. • The maximum load of RCCI could be extended from 81 (reference) to 101 kW of BP. In this study, the effects of modifications of both the piston shape and injector nozzle are experimentally investigated for high load extension of a natural gas–diesel dual-fuel reactivity-controlled compression ignition (RCCI) engine. First, a bathtub shape with a reduced compression ratio is applied to the modified piston which was reported to improve the flame propagation in squish volume, the cooling loss, and the air induction rate under the same limit of in-cylinder pressure from previous studies. In addition, a multiangle two-layer injector is used to extend the maximum load, which has been proven to be effective for unburned hydrocarbon emissions and gross indicated efficiency in part-load operation in our previous study. The experiments are conducted under both 1200 rpm part-load operation (approximately 1950 J/cylinder per cycle of fuel input energy) and 1800 rpm maximum load operation. The objectives are to comprehensively evaluate the effects of the modifications on natural gas–diesel RCCI operation and verify the effects of all load conditions. The experimental results reveal that the changes in the piston—reduction in the compression ratio and a bathtub piston shape—are effective for both NOx and smoke emissions as the diesel injection timing is advanced. Although the multi-hole double layer (combined narrow and wide injection) has less effect on emissions compared to that of the change in piston, it affects the mixing process inside the cylinder, thus retarding the combustion phasing, prolonging the combustion duration, and eventually reducing the cooling loss. Both modifications are highly effective for advanced diesel injection timing corresponding to RCCI operation, which extends high-load operation from 80.9 to 101 kW of brake power, relatively 24.8 % increase, by adopting both the piston and injector modifications. Based on the modifications, the mass fraction of natural gas is suggested to be approximately 80 %. A higher fraction causes the variation in the maximum in-cylinder pressure to be extremely sensitive to allow robust operation. In contrast, if it is lower, the amounts of both NOx and smoke emissions exceed the emission standard levels (0.4 g/kWh and 15 mg/kWh for NOx and smoke emissions, respectively, corresponding to Stage-V of non-road engine operation).

Influence of fuel mixture and catalyst on the ethanol burner flue gas composition

The aim of this study is to determine the influences of chosen primary (mixing of standard recommended fuel with additives) and secondary (oxidation catalyst) measures on the composition of flue gas, produced by combustion of liquid fuels in a standard ethanol burner. The total amount of emitted NOx was decreased by 63%, after replacing the fuel by pure methanol, while the total amount of emitted CO was the lowest during pure ethanol usage. The implementation of chosen catalyst significantly affected the total amount of emitted CO with high conversion rates (82%–90%). The amount of emitted water vapour was increased by 0%–25% (per 1 kWh of released energy) when additives were used. Overall, applying the mentioned measures together proved to be very beneficial from the total amount of emitted CO and NOx point of view.

Co-combustion of sewage sludge and Zhundong coal: Effects of combustion conditions on gaseous pollutant emission and ash properties

The combustion of sewage sludge (SS) generates large amounts of NOx and SOx, while that of alkali and alkaline earth metal-rich coals produces slagging-prone ash. To determine whether these problems can be mitigated through the co-combustion of SS and coal, we examined the effects of SS and Zhundong coal co-combustion in a horizontal tubular furnace on the emission of NOx and SOx, analyzing the micromorphology, composition, and pore structure of the produced ash. Sludge content was inversely correlated with SO2 emission but had little effect on NOx emission. A high sludge content promoted the fusion of ash particles, whose size was positively correlated with combustion temperature. Na/Ca-feldspar miscibility led to the fusion of ash particles, facilitating the production of magnesia-iron spinel and complex phosphates to alleviate slagging. The specific surface area of ash was negatively correlated with temperature and was the largest at a sludge content of 20 wt%. The fractal dimensions calculated to examine pore structure complexity and pore surface roughness revealed that the latter parameter was inversely correlated with temperature. A reaction temperature of 900 °C and sludge content of 20 wt% were optimal conditions for gaseous pollutant emissions and ash agglomeration behaviors during co-combustion. Thus, this study provides a theoretical basis for controlling the operation of coal/SS co-fired power plants in terms of pollutant emission, combustion efficiency, and ash slagging.

Effect of framework Al pairing on NO storage properties of Pd-CHA passive NOx adsorbers

Three Pd/H-CHA samples were prepared containing 53.0 %, 10.8 % and 6.5 % paired Al sites at near fixed Si/Al ratio and similar Pd loading. According to H2 temperature-programmed reduction, Pd was present almost exclusively as isolated cations in the two samples containing the higher concentrations of paired Al sites, whereas in the other sample PdO was also present. Simulated lean cold start tests on the fresh samples conducted in a microflow reactor showed that the sample containing PdO stored the lowest amount of NOx. When tested with CO/H2, the sample containing 53.0 % paired Al sites showed significantly better storage capacity than the other samples and deactivated less rapidly upon sequential tests. Experiments using lean gasoline engine exhaust revealed similar trends. This study showed that a high concentration of paired Al sites in Pd/H-CHA is beneficial for NOx storage capacity, thermal durability, and minimizing deactivation in the presence of CO/H2.

Establishment of High-Resolution Emissions Inventory in Wuhai and Its Application in Exploring the Causes of Ozone Pollution

Wuhai is a typical coking industrial base including three industrial parks within its jurisdiction. The emission amount of air pollutants is considerable here, and O3 pollution has become serious in recent years. Clarifying the air pollutant emission characteristics and exploring the formation mechanism of O3 are the basis for objectively understanding the O3 pollution and formulating scientific prevention and control measures. This study established the high-resolution emission inventory of Wuhai in 2018 (HEI-WH18) based on the "coefficient method," evaluated the applicability and accuracy of HEI-WH18 using the WRF-Chem model, and explored the causes of O3 pollution in summer using WRF-Chem diagnosis module output. The HEI-WH18 showed that the total emissions amount of SO2, NOx, CO, PM10, PM2.5, VOCs, NH3, BC, and OC were 65943, 40934, 172867, 159771, 47469, 69191, 1407, 1491, and 1648 t·a-1, respectively. HEI-WH18 could capture the variation and magnitude of O3 and its precursors better than the MEIC, which was suitable for the O3 simulation and source analysis in summer. From the perspective of spatial distribution, Haibowan was a high-value area of O3 during the daytime, and the three industrial parks were low-value areas of O3 and high-value areas of NO2 during the daytime and nighttime. The spatial distribution characteristics of CO were consistent with the spontaneous combustion of coal and coal gangue sources. According to the diagnostic analysis of two O3 pollution processes, the O3 increase in the upper boundary layer was mainly related to the advection transport and chemical process, and it was caused by vertical mixing and the advection transport process in the lower boundary layer. The contribution of the chemical process in the lower boundary layer was complicated, and its positive contribution played a role in maintaining a high O3 concentration, whereas its negative contribution combined with advection transport resulted in the final dissipation of O3 pollution.

Nitrogen Migration and Conversion in Chars from Co-Pyrolysis of Lignocellulose Derived Pyrolysis Model Compounds and Urea-Formaldehyde Resin Adhesive

In thermal conversion utilization, nitrogen-rich biomass such as waste wood-based panels will release a large amount of NOx into the atmosphere, causing serious harm to the surroundings. By means of co-pyrolysis, N in waste wood-based panels can be fixed in chars instead of discharging into the atmosphere in the form of volatile matter, which can reduce NOx emission and lay a foundation for the preparation of nitrogen-rich carbon materials with high added value. As the most commonly used adhesive in the production of wood-based panels, urea-formaldehyde resin adhesive (UF) is the main nitrogen source in waste wood-based panels. Therefore, the purpose of this paper is to explore the effects of glucose, ethyl maltol and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) on nitrogen migration and conversion during UF pyrolysis by adjusting the different proportions of model compounds and UF. Thermogravimetric analysis showed that ethyl maltol and DMHF had lower thermal stability and the pyrolysis process was concentrated in the range of 90–168 °C, which does not coincide with the mass loss temperature of UF. UF can promote the pyrolysis of these three model compounds at the initial stage to some extent. The elemental analysis showed that the N retention in co-pyrolysis chars increased in varying degrees with the increase of the addition of model compounds; the nitrogen retention in chars of glucose-UF, ethyl maltol-UF and DMHF-UF increased by 28.47%, 3.48% and 16.45% with the increase of the model compound content from 50% to 90%, respectively. The XPS results showed that the relative content of N-6 in chars increased with the increase of ethyl maltol content, and the relative content of N-5 in chars increased with the increased addition of DMHF. Glucose had little effect on the distribution of N-functional groups in chars.

Characterization of air pollutant emissions from construction machinery in Beijing and evaluation of the effectiveness of control measures based on information code registration data.

Non-road mobile machinery (NRMM), mainly construction machinery, has a high emission intensity of air pollutants, significantly impacting urban air quality. Most previous estimates of NRMM emissions have employed a top-down approach mainly based on estimates of energy consumption, leading to large uncertainties. This study uses the information code registration data specified in the latest regulations to establish a bottom-up method for emission accounting to more precisely identify the characteristics of air pollutant emissions from construction machinery in Beijing in 2020. Moreover, the study evaluates the effectiveness of the implementation of the corresponding control measures in conjunction with the current situation of pollution control of NRMM in Beijing. The results show the following: (1) Based on the information code registration data, there are 37,000-based fuel construction machines, with excavators accounting for the largest proportion (56%), loaders and forklifts also accounting for large proportions (19% and 15%, respectively), representing the main types of construction machinery. (2) Information code registration data better reflect the actual situation of construction machinery emissions than the top-down method; the emissions of the main air pollutants NOx, PM2.5, and VOCs amount to 12,000 tons, 600 tons, and 1000 tons, respectively, which are overestimated to some extent by the top-down method. (3) Loaders and excavators have a large contribution to emissions, accounting for 80-91% of these three pollutants emissions; there is a large quantity of machinery classified into the China III standard, accounting for 64-68% of these pollutants emissions; the designation of low emission zones banning the use of high-emission machinery plays a positive role in pollution reduction, but high-emission machinery is still used in these regions, which requires further attention. (4) In the future, the scope of these regions banning high-emission machinery and the types of controlled machinery should be further expanded, and the supervision and enforcement should be strengthened, Furthermore, the structural adjustment and energy conservation of construction machinery should be promoted, and measures such as electrification should be implemented for part of the light construction machinery to continue to reduce pollutant emissions.

Effects of propeller load fluctuations on performance and emission of a lean-burn natural gas engine at part-load conditions

Providing stable combustion of lean-burn natural gas engines was always a big challenge, particularly during a low load operation. In transient sea conditions, there is an additional concern due to irregular time-varying loads. Therefore, this study aimed at investigating the part-load operation of a marine spark-ignition lean-burn natural gas engine by simulating the entire engine. The engine's essential components are modeled, including air manifold, intake valves, fuel system, controllers, combustion chamber, exhaust valves, exhaust manifold and turbocharger.In steady-state, the results of emission compounds from modeling have been compared to measured data from 25% to 100% loads. For transient conditions, for the sample time of about 50 min, the fuel flow and turbocharger output are selected from the vessel logged data and compared with the simulation results. The model has shown the great potential of predicting the engine response throughout the steady-state and transient conditions. Simulating the engine at part-load transient condition showed that the unburned hydrocarbon formation, known as methane slip in lean-burn gas engines, is more than the part-load steady-state. This increase of methane slip is due to the combustion instability in lower loads and flame extinguishing in such transient conditions. The engine measured data shows a double amount of methane slip in a 25% load than the 100% load in steady-state. However, the simulation output in the transient conditions confirms an increase in methane slip over four times than equivalent steady-state load. Moreover, the lean-burn gas engine releases less NOX in part-load operation in a steady-state due to lower in-cylinder temperature. In transient conditions, there is remarkable instability in excess air ratio. Due to this instability, there is a rich mixture in instantaneous time steps during loads up. Therefore, it will result in an unusually high amount of NOX, and more than two times in comparison with the equivalent steady-state output.

Buffer effect of MgO on Na2SO3 to stabilize S(IV) for the enhancement in simultaneous absorption of NOx and SO2 from non-ferrous smelting gas.

Oxidation-reduction-absorption based on sulfite is a promising process for simultaneous removal of NOx and SO2. However, excessive oxidation of sulfite and competitive absorption between NOx and SO2 limit its application. A matching strategy between antioxidants and alkaline agents has been proposed to solve these problems and enhance the absorption process. The comparison results of inhibitors showed that hydroquinone exhibited long-term high-efficiency inhibition of S(IV) (SO32-/HSO3-) oxidation. The comparison of alkaline agents showed that the Na2SO3 solution with heterogeneous mixture of MgO and hydroquinone exhibited better absorption performance than that with other combinations. The absorption amounts of NOx in 0.15mol/L Na2SO3 50mL solution added 0.1% hydroquinone (HQ) with 0.09mol/L MgO were 2.24mmol, which improved 5 times than that without additives. In addition, studies on the influence of pH showed that the pH of MgO mixture could be stabilized at 9-10 for a long time, while the pH of Na2CO3 mixture decreased faster. Further studies suggested that the hydration of MgO resulted in the solution with MgO keeping high pH. This is also the main reason why the combination of MgO and hydroquinone is superior to the combination of Na2CO3 and hydroquinone in desulfurization and denitration performance.

Application of modified fuel in internal combustion engines to reduce pollutants in exhaust gases

This work presents the results of the study of the effect of water in the dissolved state in diesel fuel, as well as in the form of a water-fuel emulsion. The question of the expediency of using modified diesel fuel is being considered. Experimental data show that a decrease in the intensity of nitrogen oxides formation occurs due to the transfer of diesel fuel from fuel oil to a water-fuel emulsion. The use of an emulsion has the effect of reducing the volume of active zones of nitrogen oxide formation, and also reduces the maximum local gas temperatures. As a result of the conducted studies of water-fuel systems on the 1H 15/18 engine, in which water molecules were in a dissolved state in the form of true solutions. To improve the solubility of water, modifiers of various nature (high-molecular alcohol and quaternary ammonium base salt) were introduced into diesel fuel. During the research, it was found that the presence of dissolved water in the upgraded fuel leads to a decrease in the amount of toxic pollutants CO and NOx in the exhaust gases.

Experimental Investigation of the impact of boron nanoparticles and CNG on performance and emissions of Heavy-Duty diesel engines

In the present study, a six cylinder heavy-duty type engine with 11,670 cc cylinder volume was used. Engine performance and exhaust emission variation were investigated by adding boron that has 20 nm-sized and hexagonal crystal structure and CNG to diesel fuel at certain rates. In this way, it was aimed to provide a contribution to the literature. All experiments were fulfilled under a constant engine speed of 500 rpm and a load of 25, 50, 75 and 100 Nm. Boron additive has been observed to improve the BSFC and BTE. Compared to the pure diesel fuel, 50 and 100 ppm nano boron added diesel fuels (without CNG), the BSFC value decreased by 4.10, 2.52 %, and the BTE value increased by 2.92, 2.11 %, respectively, based on the average of the values at all loads. It has been observed that 50-ppm Boron additive is relatively better than 100-ppm Boron additive in regards to BTE and fuel economy. Compared to the pure diesel fuel, in the diesel fuel added with CNG at the ratios of 500, 1250 and 2000 g/h, the BTE value decreased by an average of 10.39, 27.21 and 39.74%, and the BSFC value increased by 7.63, 27.43 and 49.88%, respectively, under 100 Nm load. It was observed that the BTE and BSFC values worsened in relation to the increase in the CNG amount in the fuel blend. Under 100 Nm load, in comparison with pure diesel fuel, in the diesel fuel blend added with 50 and 100 ppm boron (without CNG), there was a decrease respectively in the CO amount by 22.4 and 23.6%, in the HC amount by 18.1 and 22.0% and in the CO2 amount by 4.2 and 3.1 %, while the NOx amount increased by 13.7 and 12.7 %. Under 100 Nm load, in comparing with pure diesel fuel, in the fuel blends added with 500, 1250 and 2000 g/h CNG, significant increases in the CO emission (avg. 7.5, 15.9 and 25.1 times, respectively) and in the HC emission (avg. 2.4, 4.1 and 5 times, respectively) were determined. On the other hand, the amount of NOx decreased by 40.5, 59.4 and 68.2 % (avg.), respectively, and the amount of CO2 decreased by 8.8, 16.7 and 22.5% (avg.), in the 500, 1250 and 2000 g/h CNG added fuel blends compared to the pure diesel fuel under 100 Nm load.

Promoting Pedestrian Transportation to Reducing Air Pollution from Urban Transport

Increasing air pollution around the world causes many problems, especially in the field of health. Air pollution affects not only human health but also other living things' health. The factors that cause air pollution the most are heating, industry, and transportation. Many countries in the world carry out various studies to reduce the effect of these factors on air pollution. Especially in the field of transportation, studies have been done quite a lot in recent years. In this study, air pollution caused by transportation in Erzurum, Turkey has been investigated. Emission amounts of NOX, PM10, and SO2 values have been calculated according to the types of vehicles in the city. Then, the amount of emissions from transportation in the total sector has been revealed. The transportation structure of the city has examined in general terms and the missing aspects in terms of pedestrian transportation have been revealed. Finally, some solution proposals aiming to encourage the use of pedestrian transportation and micro mobility vehicles in order to reduce motor land vehicles are presented.

Prediction of NOx Concentration at SCR Inlet Based on BMIFS-LSTM

As the main energy source for thermal power generation, coal generates a large amount of NOx during its incineration in boilers, and excessive NOx emissions can cause serious pollution to the air environment. Selective catalytic reduction denitrification (SCR) selects the optimal amount of ammonia to be injected for denitrification based on the measurement of NOx concentration by the automatic flue gas monitoring system. Since the automatic flue gas monitoring system has a large delay in measurement, it cannot accurately reflect the real-time changes of NOx concentration at the SCR inlet when the unit load fluctuates, leading to problems such as ammonia escape and NOx emission exceeding the standard. In response to these problems, this paper proposes an SCR inlet NOx concentration prediction algorithm based on BMIFS-LSTM. An improved mutual information feature selection algorithm (BMIFS) is used to filter out the auxiliary variables with maximum correlation and minimum redundancy with NOx concentration, and reduce the coupling and dimensionality among the variables in the data set. The dominant and auxiliary variables are then fed together into a long short-term memory neural network (LSTM) to build a prognostic model. Simulation experiments are conducted using historical operation data of a 300 MW thermal power unit. The experimental results show that the algorithm in this paper reduces the average relative error by 3.45% and the root mean square error by 1.50 compared with the algorithm without auxiliary variable extraction, which can accurately reflect the real-time changes of NOx concentration at the SCR inlet, solve the problem of delay in NOx concentration measurement, and reduce the occurrence of atmospheric pollution caused by excessive NOx emissions.

Effect of cobalt incorporation on the stability of ionic Pd in the presence of carbon monoxide over Pd/BEA passive NOx adsorbers

Bimetallic PdCo/BEA zeolites were evaluated for the first time as potential passive NOx adsorbers (PNAs) in the presence of carbon monoxide (CO). The NOx:Pd ratio of Pd/BEA and PdCo/BEA catalysts decreased during 5 consecutive NOx + CO adsorption/desorption cycles due to loss of ionic Pd. The amount of NOx desorbed at T < 200 °C (weakly adsorbed NOx) was slightly increased over monometallic Pd/BEA, while the amount of NOx desorbed at T > 200 °C (strongly adsorbed NOx) was continuously decreased during 5 consecutive NOx + CO adsorption/desorption cycles. This behavior can be attributed to a decrease in the Pd2+ adsorption sites through formation of PdO. Specifically, part of Pd2+ can be reduced to Pd0 in the presence of CO and Pd0 can be further oxidized to PdO during oxidative pretreatments. Unlike Pd/BEA, the amount of weakly adsorbed NOx was decreased and the amount of strongly adsorbed NOx was amplified over bimetallic PdCo/BEA PNAs. Microscopic images, O2-temperature programmed desorption, and H2-temperature programmed reduction experiments over Pd/BEA and PdCo/BEA after cycling showed that Co incorporation in Pd/BEA zeolites suppressed PdO formation in the presence of CO. These results demonstrated that Co incorporation in Pd/BEA zeolites can stabilize the Pd2+ adsorption sites, thus provide higher amount of NOx desorption at temperatures > 200 °C. In situ diffuse reflectance infrared spectroscopy experiments showed that the amount of Pd2+ decreased upon Co incorporation, while the adsorbed NOx species remained unaltered. Density functional theory calculations found that Co experienced a direct bonding interaction with Pd, providing overall stability.

Automated Estimation of Construction Equipment Emission Using Inertial Sensors and Machine Learning Models

The construction industry is one of the main producers of greenhouse gasses (GHG). With the looming consequences of climate change, sustainability measures including quantifying the amount of air pollution during a construction project have become an important project objective in the construction industry. A major contributor to air pollution during construction projects is the use of heavy equipment. Therefore, efficient operation and management can substantially reduce a project’s carbon footprint and other environmental harms. Using unintrusive and indirect methods to predict on-road vehicle emissions has been a widely researched topic. Nevertheless, the same is not true in the case of construction equipment. This paper describes the development and deployment of a framework that uses machine learning (ML) methods to predict the level of emissions from heavy construction equipment. Data is collected via an Internet of Things (IoT) approach with accelerometer and gyroscope sensors as data collection nodes. The developed framework was validated using an excavator performing real-world construction work. A portable emission measurement system (PEMS) was used along with the inertial sensors to record the amount of CO, NOX, CO2, SO2, and CH4 pollution emitted by the equipment. Different ML algorithms were developed and compared to identify the best model to predict emission levels from inertial sensors data. The results show that Random Forest with the coefficient of determination (R2) of 0.94, 0.91, and 0.94, and normalized root-mean-square error (NRMSE) of 4.25, 6.42, and 5.17 for CO, NOX, and CO2, respectively, was the best algorithm among different models evaluated in this study.

Key Properties and Parameters of Pd/CeO2 Passive NOx Adsorbers

In this paper, a series of Pd/CeO2 catalysts prepared by different synthesis routes and showing different morphological and textural properties have been investigated for passive NOx adsorption (PNA) applications. The results obtained by NOx adsorption/desorption tests demonstrated that NOx storage capacity and NOx storage efficiency of Pd/CeO2 materials depend strictly on their surface area, whereas the morphology of the support and the Pd deposition method do not seem to play a key role. In contrast, the Pd deposition method does impact the dynamics of NOx desorption by affecting the amount of NOx desorbed at different temperatures. This seems to be connected to Pd–Ce interactions at the nanoscale that favor NOx desorption at higher temperatures suitable for PNA application. These findings are relevant in designing and optimizing the properties of Pd/CeO2 materials for their function as passive NOx adsorbers.