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The reduction of NO by CO was proposed to be applied for regeneration gas to remove NOx from industrial flue gas with activated carbon purification technology.

With the rapid increase in GPS data collection through pervasive use of mobile devices, it has become an important problem to discover significant places of moving objects from complex spatial and temporal trajectories. This problem is challenging mainly because such trajectory data suffer from several issues including incompleteness, low quality, high redundancy, and oftentimes trajectory points do not follow Gaussian distribution . We propose a clustering-based method with temporal and spatial semantics, referred to as Stops and Moves of Trajectories using Attribute Selection (SMoTAS), whose technical advantages are multifold. Firstly, it improves data availability by using a self-adaptive algorithm to correct the deviation in traditional speed-based methods. Secondly, it improves place mining accuracy by filtering multi-label clustering results when there is a lack of detailed geographic data. Thirdly, it employs feature selection to exploit the core attributes of clustering and simplify the clustering results with Grubbs criterion. Experimental results on real-life datasets show that SMoTAS not only achieves substantial improvement of accuracy over existing methods in discovering significant places, but also exhibits superior adaptability to different trajectories and application scenarios.

PurposeThis paper aims to examine the critical role played by cultural flow in fostering successful expatriate cross-border transitions.Design/methodology/approachThe authors develop and test a model on the interplay among cultural intelligence, organizational position level, cultural flow direction and expatriate adaptation, using a data set of 387 expatriate on cross-border transitions along the Belt & Road area.FindingsThe authors find that both organizational position level and cultural flow moderate the relationship between cultural intelligence and expatriate adaptation, whereby the relationship is contingent on the interaction of organizational position status and assignment directions between high power distance and low power distance host environments.Originality/valuePrevious research has shown that higher levels of cultural intelligence are positively related to better expatriate adaptation. However, there is a lack of research on the effect of position difference and cultural flow on such relationship. Our study is among the first to examine how the interaction between cultural flow and organizational position level influences the cultural intelligence (CI) and cultural adjustment relationship in cross-cultural transitions.

A Particulate Matter (PM) inhalation model considering exercise load is established to evaluate the impact of PM on residents' travel health. The study chooses PM detectors to collect PM concentrations at the various transportation space, including walking, bicycle, bus, taxi, and subway. A multiple linear regression model revised by road greening is utilized to study the influence factors that have a potential impact on the PM concentration. The air inhalation model with the consideration of exercise load can be acquired by connecting the heart rate (HR) and individual characteristics. The PM

In the field of nitrogen oxides (NO

The main purpose of this study is to explore the relationships between cultural intelligence (CQ) and organizational commitment in Belt & Road area, with critical consideration given to the moderating effect of cultural distance (CD) on the commensurate relationships. We examined a dataset of 390 international professionals on Chinese cross-border projects in Belt & Road countries. Findings indicate that cognitive CQ has an inverted U-shaped relationship with organizational commitment, while motivational CQ has a positive linear relationship with organizational commitment, and cultural distance moderates the relationships between CQ and commitment such that negative or positive moderation occur contingent on whether the optimal CQ level is reached. Our results suggest the need for identifying an inflection point of individuals’ CQ level to differentiate between the increasing and decreasing trend of organizational commitment in view of the effect of cultural distance. This may help enabling multinationals to leverage expatriates with different levels of CQ to stay committed in multi-cultural environments along the Belt & Road countries.

In the data mining of road networks, trajectory clustering of moving objects is of particular interest for its practical importance in many applications. Most of the existing approaches to this problem are based on distance measurement, and suffer from several performance limitations including inaccurate clustering, expensive computation, and incompetency to handle high dimensional trajectory data. This paper investigates the complex network theory and explores its application to trajectory clustering in road networks to address these issues. Specifically, we model a road network as a dual graph, which facilitates an effective transformation of the clustering problem from sub-trajectories in the road network to nodes in the complex network. Based on this model, we design a label-based trajectory clustering algorithm, referred to as LBTC, to capture and characterize the essence of similarity between nodes. For the evaluation of clustering performance, we establish a clustering criterion based on the classical Davies-Bouldin Index (DB), Akaike Information Criterion (AIC), and Bayesian Information Criterion (BIC) to maximize inter-cluster separation and intra-cluster homogeneity. The clustering accuracy and performance superiority of the proposed algorithm are illustrated by extensive simulations on both synthetic and real-world dataset in comparison with existing algorithms.

SO2 will form SO3 in the selective catalytic reduction (SCR) of NO over a V2O5/TiO2 catalyst. To reduce the total amount of SO2 oxidation products, the distribution of the sulfur-containing species...

The reduction of NO by the CO produced by incomplete combustion in the flue gas can remove CO and NO simultaneously and economically. However, there are some problems and challenges in the industrial application which limit the application of this process. In this work, noble metal catalysts and transition metal catalysts used in the reduction of NO by CO in recent years are systematically reviewed, emphasizing the research progress on Ir-based catalysts and Cu-based catalysts with prospective applications. The effects of catalyst support, additives, pretreatment methods, and physicochemical properties of catalysts on catalytic activity are summarized. In addition, the effects of atmosphere conditions on the catalytic activity are discussed. Several kinds of reaction mechanisms are proposed for noble metal catalysts and transition metal catalysts. Ir-based catalysts have an excellent activity for NO reduction by CO in the presence of O2. Cu-based bimetallic catalysts show better catalytic performance in the absence of O2, in that the adsorption and dissociation of NO can occur on both oxygen vacancies and metal sites. Finally, the potential problems existing in the application of the reduction of NO by CO in industrial flue gas are analyzed and some promising solutions are put forward through this review.

The iron and steel industry is not only an important foundation of the national economy, but also the largest source of industrial air pollution. Due to the current status of emissions in the iron and steel industry, ultra-low pollutant emission control technology has been researched and developed. Liquid-phase proportion control technology has been developed for magnesian fluxed pellets, and a blast furnace smelting demonstration project has been established to use a high proportion of fluxed pellets (80%) for the first time in China to realize source emission reduction of SO

High carbon consumption is an important factor restricting the wide application of activated carbon technology for flue gas purification. A fixed-bed reactor combined with a Fourier transform infrared (FTIR) spectrometer was used to explore the source of carbon consumption at various SO2 concentrations and cyclic adsorption-regeneration times. The results demonstrate that carbon consumption originates from two sources and is mainly determined by the reaction of H2SO4 and C at high SO2 concentrations and by the thermal decomposition of oxygen-containing functional groups at low SO2 concentrations. An interesting observed phenomenon is that carbon consumption does not increase as the SO2 concentration increases. The conversion mechanism reveals that carboxylic and anhydride groups are converted to phenol and quinone groups, which do not easily decompose with increasing SO2 concentration. In the process of cyclic adsorption-regeneration, it is discovered that the carbon consumption in the first cycle is several times higher than that in the following cycles due to the decomposition of functional groups from the activated carbon itself. The regeneration mechanism of functional groups has been elucidated. The carboxylic acid and the phenolic hydroxyl on the surface of activated carbon are consumed in the regeneration process and formed again from the conversion of carbonyl groups in the next adsorption process under the roles of O2 and H2O. It is proposed that the functional groups are regenerated in the adsorption process rather than in the regeneration process.

The emission of volatile organic compounds (VOCs) from coking industry severely reduces air quality. Using both offline and online methods, the emissions of 124 VOCs and non-methane hydrocarbon (NMHC) in a typical top-charging coke oven were analyzed during the coking process (emissions form the coke oven flue gas, charging, pushing, coke dry quenching, and topside of the coke oven). The concentrations of VOCs in coke oven flue gas and exhaust gas during charging were the highest, which reached 98.2 mg/m

In the process of flue gas purification with activated coke, sulfuric acid and sulfate are deposited on the activated coke surface; therefore, thermal regeneration is needed to recover the activated coke activity, which leads to carbon consumption. In this work, various regeneration parameters, including temperature, time and atmosphere, were investigated to optimize carbon consumption. The experimental results showed that the desulfurization capacity of the activated coke was clearly improved after thermal regeneration, while the denitrification capacity demonstrated no obvious or regular changes. Based on dozens of groups of regeneration experiments, it was found that the chemical carbon consumption per mol SO2 recovery ranged from 0.5 to 2.0 mol, which was higher than the theoretical value of 0.5 mol. The proportion of CO2 in chemical carbon consumption ranged from 60%–80% with an average value of 70%, and the rest was CO. According to the results from temperature-programmed desorption (TPD), CO and CO2 consumption was mainly derived from the decomposition of carboxyl and anhydride groups, with a small contribution from the reduction reaction of sulfuric acid with carbon. CO and CO2 consumption occupied only 10%–18% of the total carbon-containing functional groups, so the reaction activity was retained after thermal regeneration. The carbon consumption in an NH3/N2 atmosphere was smaller than that in a N2 atmosphere, which was about half of that in a H2O/N2 atmosphere due to the inhibition of carboxyl group decomposition, based on the results from TPD and in situ diffuse reflectance infrared Fourier transform (In situ DRIFT). Analysis of the thermal regeneration process in four iron and steel factories revealed that the chemical carbon consumption of activated coke accounted for approximately 20%–40% of the total carbon consumption, which was smaller than the contribution from physical carbon abrasion.

Activated carbon (AC) has the advantage of multi-pollutant control with a high removal efficiency for flue gas purification. It is necessary to determine the oxidation mechanism and oxidation products of hydrogen sulfide (H2S) on AC to simultaneously capture H2S and SO2. A fixed-bed reactor was coupled with a mass spectrometer (MS) to detect the gaseous components and X-ray photoelectron spectroscopy (XPS) was used to distinguish the sulfur-containing species in the oxidation products on AC and thermally treated AC to investigate the actions of the oxygen-containing functional groups. The results revealed that H2S was adsorbed on the AC surface and combined with oxygen-containing functional groups to form sulfate (SO42−) in the absence of O2. In the presence of O2, H2S and O2 in the atmosphere were adsorbed on the AC active sites, and the catalytic reaction produced elemental sulfur. Elemental sulfur further reacted with O2 to produce gaseous SO2. According to the detection results of XPS and the in situ diffuse reflectance infrared Fourier transform (in situ DRIFT) spectra, an oxidation mechanism of H2S by O2 and oxygen-containing functional groups was described. The C=C and C=O bonds were broken by H2S, and then, C-S and S-O bonds of the intermediate products were generated. The C-S bond tended to form elemental sulfur, while the S-O bond likely formed a sulfate or gaseous SO2. Porosity analysis showed that the AC specific surface area decreased after H2S adsorption and that sulfate reduced the specific surface area much more than elemental sulfur.

Currently, activated coke is widely used in the removal of multiple pollutants from industrial flue gas. In this paper, a series of novel FexLayOz/AC catalysts was prepared by the incipient wetness impregnation for NH3-SCR denitrification reaction. The introduction of Fe-La bimetal oxides significantly improved the denitrification performance of activated coke at mid-high temperature, and 4% Fe0.3La0.7O1.5/AC exhibited a superior NOx conversion efficiency of 90.1% at 400 °C. The catalysts were further characterized by BET, SEM, XRD, Raman, EPR, XPS, FTIR, NH3-TPD, H2-TPR, et al., whose results showed that the perovskite-type oxide of LaFeO3 and oxygen vacancies were produced on the catalysts’ surfaces during roasting. Fe-La doping enhanced the amount of acid sites (mainly Lewis and other stronger acid sites) and the content of multifarious oxygen species, which were beneficial for NOx removal at mid-high temperature. Moreover, it was investigated that the effect of released CO from activated coke at mid-high temperature on the NOx removal through the lifetime test, in which it was found that a large amount of CO produced by pyrolysis of activated coke could promote the NOx removal, and long-term escaping of CO on the activated coke carrier did not have a significant negative impact on catalytic performance. The results of the TG-IR test showed that volatile matter is released from the activated coke while TG results showed that the weight loss rate of 4% Fe0.3La0.7O1.5/AC only was 0.0015~0.007%/min at 300–400 °C. Hence, 4% Fe0.3La0.7O1.5/AC had excellent thermal stability and denitrification performance to be continuously used at mid-high temperature. Finally, the mechanisms were proposed on the basis of experiments and characterization results.

The oxidation of sulfur dioxide (SO2) to sulfur trioxide (SO3) is an undesirable reaction that occurs during the selective catalytic reduction (SCR) of nitrogen oxides (NOx) with ammonia (NH3), which is a process applied to purify flue gas from coal-fired power plants. The objectives of this work were to establish the fundamental kinetics of SO3 formation over a V2O5/TiO2 catalyst and to illustrate the formation mechanism of SO3 in the presence of NOx, H2O and NH3. A fixed-bed reactor was combined with a Fourier transform infrared (FTIR) spectrometer and a Pentol SO3 analyser to test the outlet concentrations of the multiple components. The results showed that the rate of SO2 oxidation was zero-order in O2, 0.77-order in SO2 and -0.19-order in SO3 and that the apparent activation energy for SO2 oxidation was 74.3 kJ mol−1 over the range of studied conditions. Based on in situ diffuse reflectance infrared Fourier transform (in situ DRIFT) spectroscopy, X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) tests, the SO3 formation process is described here in detail. The adsorbed SO2 was oxidized by V2O5 to produce adsorbed SO3 in the form of bridge tridentate sulfate, and the adsorbed SO3 was desorbed to the gas phase. NOx promoted the oxidation of the adsorbed SO2 due to the promotion of the conversion of low-valent vanadium to high-valent vanadium. In addition, the desorption of the adsorbed SO3 was inhibited by H2O or NH3 due to the conversion of tridentate sulfate to the more stable bidentate sulfate or ammonium bisulfate. Finally, the mechanism of the influence of NOx, H2O and NH3 on the formation of gaseous SO3 was proposed.

The existing catalysts based on activated coke had generally poor denitration performance at low temperature, which could not meet the urgent needs of power plants and steel enterprises. In this study, activated coke loaded with FexCoyCezOm was prepared by incipient wetness impregnation method and employed to remove NOx at 100–350 °C in simulated flue gas. 3%Fe0.6Co0.2Ce0.2O1.57/AC catalyst exhibited highest NOx removal efficiency as it had more than 70%NOx conversion rate at 100 °C and achieved more than 90%denitrition efficiency at 250–350 °C. The catalyst also showed stable catalytic performance and good resistance to H2O or/and SO2 at 250 °C. Based on the results of Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), temperature programmed desorption (TPD), temperature programmed reduction (TPR) and Fourier transform infrared spectroscopy (FTIR), the enhanced performance could be attributed to the co-participation of Fe, Co and Ce species with different valence states, the high concentration of chemisorbed oxygen, highly dispersed active components, the increase of weak acid sites, good redox properties of metallic oxides and abundant founctional groups on the catalyts surface. Finally, the possible mechanism and kinetics of NOx removal over FexCoyCezOm/AC catalyst were discussed in detail, which revealed that the enhanced performance was resulted from the increased active sites and the redox cycle among Fe, Co and Ce.

Carbon consumption of activated carbon varies with the sulfur-containing products. In this work, differential thermogravimetric (DTG), electron paramagnetic resonance (ESR), X-ray photoelectron spectroscopy (XPS), and temperature programmed desorption (TPD) were used to reveal the adsorption-regeneration process of H 2 S and the effect of adsorption products on carbon consumption. H 2 S reacts with the C=C bond to form C-S bond as an intermediate state, followed by the formation of elemental sulfur. It directly sublimates at approximately 380 °C , about 30 °C higher than the decomposition temperature of H 2 SO 4 . In the thermal regeneration process, the elemental sulfur in the form of monoclinic sulfur (S 8 ) first breaks into infinitely long chain molecules (S ∞ ) and then into small molecules, finally into sulfur vapor. The desorption of elemental sulfur consumes less oxygen and carbon functional groups, reducing the chemical carbon consumption by 59.8% than H 2 SO 4 . The compressive strength reduces less due to its slight effect on the disordered graphitic structure. H 2 S also reacts with the C=O bond to form H 2 SO 3 or H 2 SO 4 . The desorption of H 2 SO 3 does not require carbon consumption. The decomposition of H 2 SO 4 needs to react with C=C bond to release SO 2 , CO 2 , and CO, and the compressive strength of activated carbon significantly decreases. The carbon consumption originates from two aspects, the one from the regeneration of sulfur-containing products is more than twice of the other one from the decomposition of oxygen-containing functional groups.

Carbon consumption of activated carbon varies with sulfur-containing products. In this work, differential thermogravimetric (DTG), electron paramagnetic resonance (ESR), X-ray photoelectron spectroscopy (XPS), and temperature programmed desorption (TPD) we re used to reveal the adsorption-regeneration process of H

In recent years, layered double hydroxides (LDHs) derived metal oxides as highly efficient catalysts for selective catalytic reduction of NO

To clarify the effect of coking dust, sintering dust and fly ash on the activity of activated carbon for various industrial flue gas desulfurization and denitrification, the coupling mechanism of the mixed activated carbon and dust was investigated to provide theoretical reference for the stable operation. The results show that coking dust had 34% desulfurization efficiency and 10% denitrification efficiency; correspondingly, sintering dust and fly ash had no obvious desulfurization and denitrification activities. For the mixture of activated carbon and dust, the coking dust reduced the desulfurization and denitrification efficiencies by blocking the pores of activated carbon, and its inhibiting effect on activated carbon was larger than its own desulfurization and denitrification activity. The sintering dust also reduced the desulfurization efficiency on the activated carbon while enhancing the denitrification efficiency. Fly ash blocked the pores of activated carbon and reduced its reaction activity. The reaction activity of coking dust mainly came from the surface functional groups, similar to that of activated carbon. The reaction activity of sintering dust mainly came from the oxidative property of Fe2O3, which oxidized NO to NO2 and promoted the fast selectively catalytic reduction (SCR) of NO to form N2. Sintering dust was activated by the joint action of activated carbon, and both had a coupling function. Sintering dust enhanced the adsorption and oxidation of NO, and activated carbon further promoted the reduction of NOx by NH3; thus, the denitrification efficiency increased by 5%-7% on the activated carbon.

To improve the denitrification efficiency for the selective catalytic reduction of NO with NH3 in the flue gas purification process, a low-rank activated coke (AC) was treated with ammonia (NH3·H2O) solution or nitric acid (HNO3) solution to increase the content and type of nitrogen-containing functional groups, and then the role of nitrogen-containing functional groups in the reduction of NO was analyzed. The modified AC samples were characterized by N2 adsorption/desorption to determine the pore structures and by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy to detect the surface functional groups. After modification, the content of oxygen-containing functional groups on the AC surface increased, including quinone, lactone and carboxyl, which are favorable for SO2 adsorption. Meanwhile, the type and content of nitrogen-containing functional groups on the AC surface changed; these groups fall into two categories: active groups and non-active groups. Before and after the denitrification process, the regular changes in the content of active and non-active groups showed that the active groups with pyrrole-like or pyridine-like structures can promote NO adsorption and then strengthen the denitrification. On the other hand, active groups may be reduced by NH3 or oxidized by O2, referring to side reactions, to generate non-active groups such as nitro, nitrate, amine and imine. More importantly, the role of nitrogen-containing functional groups was identified in the denitrification process. This chemical modification method is effective for improving the performance of low-cost AC since the employed chemicals are commercially available.

In recent years, activated carbon technology has been applied in various industrial flue gas purifications, with a high desulfurization efficiency but a relatively low denitrification efficiency. To strengthen the denitrification performance and further clarify which physicochemical property factor dominates the reduction of NO over activated carbon, this study used four kinds of nitrogen-enriched additives to modify the activated carbon, and the denitrification efficiency increased. The results from porosity analysis and Raman spectra showed that modification reduced the specific surface area and total pore volume of the activated carbon but promoted the disorder of graphite microcrystalline structure providing the adsorption and reaction active center for NO and NH3. The oxygen-containing and nitrogen-containing functional groups were detected by X-ray photoelectron spectrometry before and after the reaction. The results revealed that the phenolic hydroxyl oxygen was transformed to carbonyl oxygen of quinone, and pyridine, pyrrole and quaternary nitrogen functional groups were converted to pyridine N-oxides and amines. The transient response experiment was employed to investigate the adsorption state of NO and NH3 in denitrification reaction by abruptly cutting off the intake of NO or NH3 under steady-state reaction. The results revealed that the reduction of NO with NH3 at 110 °C follows the Langmuir-Hinshelwood (L-H) mechanism, while at 150 °C with Elay-Rideal (E-R) mechanism and L-H mechanism. The pyridine, pyrrole and quaternary amine groups can adsorb NO in the gaseous state, and the phenolic hydroxyl group acts as the adsorption site of NH3 to produce quinones and N2 and complete the SCR reaction.

To strengthen the CO oxidation activity of activated carbon for flue gas purification, AC was modified through acid treatment and metal loading. AC-supported Cu shows excellent catalytic oxidation activity compared with other metal-modified AC samples. To investigate the action modes of Cu loaded on activated carbon and the mechanism of CO oxidation, various samples were characterized by XRD, N2O titration, SEM, N2 physisorption, TPD, H2-TPR, XPS, in situ DRIFTS and EPR. The results show that oxygen-containing functional groups increase the loading amount and dispersion of Cu. Moreover, Cu species strongly bound to oxygen-containing functional groups are the main contributors to CO oxidation. The roles of oxygen-containing functional groups are further revealed: carboxyl groups are the anchoring sites of Cu, and hydroxyl groups supply oxygen to restore the active structure. Similarly, Ce indirectly promote the oxidation activity of CO by re-oxidizing Cu+ to Cu2+, which accelerates the catalytic cycle. The reaction mechanism on AC-supported Cu samples has been proposed to follow the double-site Langmuir–Hinshelwood mechanism, with Cu2+ as oxidation sites, Cu+ as adsorption sites and the formation of oxygen vacancies on Cu+ during the reaction. AC-Cu performs the highest oxidation activity at a proportion of Cu+ of 0.5–0.6. SO2 causes irreversible chemical poisoning to CO oxidation, while NO leads to reversible poisoning due to competitive adsorption with CO. The novel AC-supported Cu catalyst with Ce improves the resistance against SO2 and NO, and the reason is explained. These findings provide theoretical guidance for the preparation and application of metal-modified activated carbon.

To reduce chemical carbon consumption in activated coke technology used for flue gas purification, the carbon consumption mechanism of commercial activated coke in the presence of water vapor was studied. A fixed-bed reactor and a Fourier transform infrared (FTIR) spectrometer were combined to study the amount of carbon consumption. Temperature-programmed desorption (TPD) coupled with in situ diffuse reflectance infrared Fourier transform (in situ DRIFT) spectra were used to investigate functional group changes of activated coke. The sources and factors influencing carbon consumption in various adsorption atmospheres and in the N2 regeneration atmosphere were compared. Carbon consumption during the adsorption and regeneration process was mainly due to the release of C-O and C=C groups. The addition of H2O increased the formation of carbonates and carboxylic acids during the adsorption process, which decomposed during the regeneration process, thereby increasing carbon consumption. Carbon consumption was reduced during regeneration in an H2O-SO2 adsorption atmosphere, mainly because of the formation of C-S bonds, which reduced the formation of CO2. The C-N bonds generated in an H2O-NO adsorption atmosphere were decomposed during the regeneration process, thereby increasing carbon consumption. In a complex atmosphere of SO2, NO, NH3, and H2O, SO2 was absorbed by NH3, and the amount of carbon consumption was consistent with that in the NO atmosphere during the regeneration process. The total carbon consumption in various adsorption atmospheres ranged from 85.4 to 125.2 μmol/g. Compared with an anhydrous atmosphere, chemical carbon consumption increased by 6.5-14.3% in the presence of H2O. Chemical carbon consumption was reduced by decreasing the H2O concentrations, which provides a reference concept for reducing the operating cost of the activated coke process in industry.

In 2019 China accounted for 14 percent of world total outward foreign direct investment, with 188 countries recipients of this investment. However research suggests that 67 percent of this investment is considered unsuccessful. Furthermore, the current Covid-19 outbreak has severely hindered global economic and trade activities. This is partly due to an under-efficiency of Chinese expatriate executives resulting from the lack of cultural intelligence of these executives to maximize team efficiency in production. From a data set of 358 expatriate Chinese executives, this research utilizes structural equation modeling to examine the role of expatriate executives' cultural intelligence on team efficiency. The research shows that the relationship between an expatriate executive's cultural intelligence and team efficiency is mediated by their ability to recognize international opportunity and moderated by openness to experience. Additional leadership development on cultural intelligence of expatriate executives will improve international efficiency and wider multinational efficiency.

In the selective catalytic reduction (SCR) of NO with NH3 over activated carbon (AC), deactivation occurs over time in the presence of SO2. This work distinguishes the multiple roles of SO2 in the gas phase versus the solid deposition product and clarifies the effects of the physicochemical properties of AC on NO conversion. The deposition products were detected using temperature-programmed desorption (TPD) coupled with mass spectrum (MS) analysis and Fourier transform infrared (FTIR) spectrometry. The results showed that the activated carbon loses less de-NOx activity when it has more CO- and CO2-containing groups with decomposition temperatures over 900 K. The Raman spectra revealed that the disorder of the microcrystalline structure of the graphite has a positive linear correlation with NO conversion regardless of the presence of functional groups. The deposition products were analyzed by Gaussian-Lorentz deconvolution of the TPD spectra, and it was discovered that the sulfur-containing species include...

Activated carbon (AC) is very effective for multi-pollutant removal; however, the complicated components in flue gas can influence each other's adsorption. A series of adsorption experiments for multicomponents, including SO2, NO, chlorobenzene and H2O, on AC were performed in a fixed-bed reactor. For single-component adsorption, the adsorption amount for chlorobenzene was larger than for SO2 and NO on the AC. In the multi-component atmosphere, the adsorption amount decreased by 27.6% for chlorobenzene and decreased by 95.6% for NO, whereas it increased by a factor of two for SO2, demonstrating that a complex atmosphere is unfavorable for chlorobenzene adsorption and inhibits NO adsorption. In contrast, it is very beneficial for SO2 adsorption. The temperature-programmed desorption (TPD) results indicated that the binding strength between the gas adsorbates and the AC follows the order of SO2>chlorobenzene > NO. The adsorption amount is independent of the binding strength. The presence of H2O enhanced the component effects, while it weakened the binding force between the gas adsorbates and the AC. AC oxygen functional groups were analyzed using TPD and X-ray photoelectron spectroscopy (XPS) measurements. The results reveal the reason why the chlorobenzene adsorption is less affected by the presence of other components. Lactone groups partly transform into carbonyl and quinone groups after chlorobenzene desorption. The chlorobenzene adsorption increases the number of C=O groups, which explains the positive effect of chlorobenzene on SO2 adsorption and the strong NO adsorption.

The adsorption of dioxin-modeling compounds on activated carbon has been investigated in this manuscript. A series of benzene compounds with different numbers and types of substituent groups were chosen as the dioxin-modeling compounds, and the gas adsorption behaviors were evaluated using a fixed-bed reactor. The adsorption results showed that the methyl, chlorine and phenolic substituent groups on a benzene ring can greatly promote gas adsorption, especially the phenolic group, the addition of which increased the adsorption capacity to more than 1.5 times that of benzene. The adsorbed AC samples were detected by TPD-MS with the combines between adsorbate and adsorbent analyzed, the methyl and chlorine groups enhanced the attraction between the gaseous compounds and AC, while the phenolic group reduced the combine force due to its oxidation on AC. The effect of an increasing number of chlorine substituents on the adsorption of gases and the combine forces were investigated. On average, the capacity of gas adsorption doubled and the desorption temperature increased by 20 K with one chlorine substituent on a benzene ring. The attachment of chlorine substituent groups to the AC lactone and quinone groups has been verified again, and the increasing chloric substituent groups consumed more oxygen groups. According to the linear relationships between gas properties and adsorption behaviors, the actual dioxin adsorption capacity has been inferred to be 600 mg/g or greater, showing that dioxin is much more easily adsorbed on AC than the conventional organic gases. (C) 2015 Elsevier B.V. All rights reserved.

A Co0.5Mn1Fe0.25Al0.75Ox-LDO catalyst was developed which showed excellent performance for the low-temperature NH3-SCR. NOx conversions ∼100% were achieved in the whole 100-250 °C range, while after 10-h operation at 150 °C with 100 ppm SO2/5 vol% H2O in the feed, the NOx conversion was maintained at 80%. This catalyst provided a much better N2-selectivity than the Mn1Fe0.25Al0.75Ox-LDO and Mn1Al1Ox-LDO, especially at 150-300 °C. It was found that Co0.5Mn1Fe0.25Al0.75Ox possessed higher surface acidity and reducibility, while XPS analyses indicated an electron transfer between Co3+/Co2+ and Mn4+/Mn3+ redox cycles, leading to a much lower N2O formation, supported by Density Functional Theory (DFT) calculations. Detailed analysis of gas responses obtained upon various step-gas switches was performed, which allowed to measure the surface concentration and reactivity of preadsorbed NOx-s and NHx-s leading to N2 and N2O. Transient kinetic and DFT studies strongly suggested likely mechanisms of NH3-SCR and the critical role of Co for N2-selectivity enhancement.