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Synergistic reduction of air pollutants and carbon dioxide (CO2) emissions is currently a key environmental policy in China, yet provincial-level studies remain scarce. To fill the gap, this study developed a coupled emission inventory from 2013 to 2020 in Shanxi, a coal-dependent province critical to China's energy security. This facilitated the investigation of emission trends, primary sources, synergistic effects, and spatial distribution. The results show that, while air pollutant emissions decreased significantly during the study period, CO2 emissions increased slightly. The main emitters of SO2, NOx, and CO2 were identified as power, heating, industrial boilers, and residential coal combustion. The iron and steel industry contributed significantly to PM2.5 emissions, coke production to VOCs, and vehicles to NOx and VOCs. NH3 emissions were mainly attributed to fertilizer use and livestock. Synergistic reductions were evident in coal-related sources, especially industrial boilers and residential coal combustion, underlining the importance of optimizing the energy structure. Anthropogenic emissions were concentrated in basins with poor dispersion conditions. Taiyuan, Yuncheng, and Linfen emerged as key areas for synergistic reduction efforts. This study provides important insights for environmental policy development in Shanxi and other coal-dependent regions.

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Improving the SO2 resistance of catalysts is crucial to driving commercial applications of Mn-based catalysts. In this work, the phosphotungstic acid (HPW) modification strategy was applied to improve the N2 selectivity, SO2 and H2O resistance of the Mn-Ce-Co catalyst, and further, the mechanism of HWP modification on enhanced catalytic performance was explored. The results showed that HPW-Mn-Ce-Co catalyst exhibits higher NOx conversion (~100% at 100-250 °C) and N2 selectivity (exceed 80% at 50-350 °C) due to more oxygen vacancies, greater surface acidity, and lower redox capacity. In situ diffused reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) reveal that HPW changed the reaction path of Mn-Ce-Co catalysts, promoted the adsorption and activation of NH3, and reduced the effect of SO2 on the active bidentate nitrate species, and thereby exhibiting good SO2 resistance. X-ray photoelectron spectrometer (XPS) and NH3 temperature-programmed desorption of (NH3-TPD) results show that HPW can inhibit the formation of metal sulfate, and SO2 can be combined with Ce species more easily. The generated Ce2(SO3)3 can not only protect Mn species but also increase the acid sites and weaken the poisoning effect of metal sulfate. This study provides a simple design strategy for the catalyst to improve the low-temperature catalytic performance and toxicity resistance.

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Nitric oxides (NOx, which mainly include more than 90% NO) are one of the major air pollutants leading to a series of environmental problems, such as acid rain, haze, photochemical smog, etc. The selective catalytic oxidation of NO to NO2 (NO-SCO) is regarded as a key process for the development of selective catalytic reduction of NOx by ammonia (via fast selective catalytic reduction reaction) and also the simultaneous removal of multipollutant (pre-oxidation and post-absorption). Until now, scholars have developed various types of NO-SCO catalysts, dividing the main groups into noble metals (Pt, Pd, Ru, etc.), metal oxides (Mn-, Co-, Cr-, Ce-based, etc.), perovskite-type oxides (LaMnO3, LaCoO3, LaCeCoO3, etc.), carbon materials (activated carbon, carbon fiber, carbon nanotube, graphene, etc.), and zeolites (ion-exchanged ZSM-5, CHA, SAPO, MCM-41, etc.) in this review. This paper summarizes the recent progress of the above typical catalysts and mostly analyzes the catalytic performance for NO oxidation in terms of the H2O and/or SO2 resistances and also the influencing factors, and their reaction mechanisms are described in detail. Finally, this review points out the key problems and possible solutions of the current researches and presents the application prospects and future development directions of NO-SCO technology using the above typical catalysts.

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A series of MnCoOx flower-like hollow microspheres with various molecular proportions of reactant were prepared through simple solvothermal method for the ammonia selective catalytic reduction (SCR) at low temperatures. The as-prepared samples have been applied by various characterization techniques to explore the formation process of the morphology and physicochemical properties. The Mn(1)Co(1)Ox presented the optimal intrinsic catalytic performance (95% NOx conversion at 75 °C), favorable thermal stability, and strong SO2 resistance. The excellent properties mainly related to its higher specific surface area and abundant active sites originated from hollow microsphere special structure consists of abundant nanosheets, robust redox properties beneficial for the strong interaction between the manganese and cobalt, larger number of acidic sites and stronger acid strength, etc., which collaboratively dominate its catalytic properties of NH3-SCR at low temperatures.

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A series of MnOx/ACFN, Ce-MnOx/ACFN, and Fe-Ce-MnOx/ACFN catalysts on selective catalytic reduction (SCR) of NOx with NH3 at low-middle temperature had been successfully prepared through ultrasonic impregnation method, and the catalysts were characterized by SEM, XRD, BET, H2-TPR, NH3-TPD, XPS, and FT-IR spectroscopy, respectively. The results demonstrated that the 15 wt% Fe(1)-Ce(3)-MnOx(7)/ACFN catalyst achieved 90% NOx conversion (100~300 °C), good water resistance, and stability (175 °C). The excellent catalytic performance of the Fe(1)-Ce(3)-MnOx(7)/ACFN catalyst was mainly attributed to the interaction among Mn, Ce, and Fe. The doping of Fe promoted the dispersion of Ce and Mn and the formation of more Mn4+ and chemisorbed oxygen on the surface of a catalyst. This work laid a foundation for the successful application of active carbon fiber in the field of industrial denitrification, especially in the aspect of denitrification moving bed. Graphic abstract.

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