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NH3-SCR performances were explored to the relationship between structure morphology and physio-chemical properties over low-dimensional ternary Mn-based catalysts prepared by one-step synthesis method. Due to its strong oxidation performance, Sn-MnOx was prone to side reactions between NO, NH3 and O2, resulting in the generation of more NO2 and N2O, here most of N2O was driven from the non-selective oxidation of NH3, while a small part generated from the side reaction between NH3 and NO2. Co or Ni doping into Sn-MnOx as solid solution components obviously stronged the electronic interaction for actively mobilization and weakened the oxidation performance for signally reducing the selective tendency of side reactions to N2O. The optimal modification resulted in improving the surface area and enhancing the strong interaction between polyvalent cations in Co/Ni-Mn-SnO2 to provide more surface adsorbed oxygen, active sites of Mn3+ and Mn4+, high-content Sn4+ and plentiful Lewis-acidity for more active intermediates, which significantly broadened the activity window of Sn-MnOx, improved the N2 selectivity by inhibiting N2O formation, and also contributed to an acceptable resistances to water and sulfur. At low reaction temperatures, the SCR reactions over three catalysts mainly obeyed the typical Elye-rideal (E-R) routs via the reactions of adsorbed l -NHx (x = 3, 2, 1) and B-NH4+ with the gaseous NO to generate N2 but also N2O by-products. Except for the above basic E-R reactions, as increasing the reaction temperature, the main adsorbed NOx-species were bidentate nitrates that were also active in the Langmuir-Hinshelwood reactions with adsorbed l -NHx species over Co/Ni modified Mn-SnO2 catalyst.

This review summarizes the synthesis, applications for the NH3-SCR and methods for strengthening the water resistance and thermal stability of MOF catalysts.

The introduction of W optimizes the electronic structure of the Co@N–C system and promotes the transfer of electrons to the surface carbon layer, thus greatly improving the HER activity.

Chlorinated benzene-containing compound (CBC) refers to a kind of volatile organic compound that contains benzene-ring and Cl atoms simultaneously, it has been widely concerned for the serious harm to human...

Cu-Co multiple-oxides modified on HNO3-pretreated activated coke (ACN) were optimized for the simultaneous removal of gaseous CO and elemental mercury (Hg0) at low temperature (

Over the years, the combined Non-thermal Plasma (NTP) denitrification process which is used for decomposition of NOx has have become an application technology with great potential. And the formation of byproducts, such as N2O and O3, which is an important factor that interfere with NO removal efficiency, has a high research value. In present study, HZSM-5 molecular sieve was selected as the packed material in dielectric barrier discharge reactor to investigate the effect of reaction conditions, such as with/without packed bed, discharge power, inner electrode diameter, electrode shape and operation time, on formation and conversion characteristics of byproducts (N2O and O3). Results showed that the presence of HZSM-5 pellets in discharge zone increases the discharge power, NO removal efficiency and the concentration of the byproducts in the outlet. The optimization of electrode diameter and the utilization of screw thread electrode increased the NO removal efficiency and the yield of N2O and O3. The pellets temperature increases with the operation time and the enhancement of input energy, which has different effects on O3 and N2O. These results provide some new methods for improving the NTP-assisted catalytic denitrification process.

In this paper, Al atomic-scale doping has been achieved by using NiAl hydrotalcite-like compounds (HTLCs) as precursors method. Regulatory effect of Al doping in NiO for carbonyl sulfide (COS) removal was studied. The samples were systematically characterized by XRD, SEM, N2 adsorption/desorption, FTIR, CO2-TPD, XPS, XAFS and In-situ DRIFTS. The results showed that the activity series for removal of COS decrease in the following sequence: Ni3Al-HTO > Ni5Al-HTO > Ni1Al-HTO. The enhanced activity after Al atomic-scale doping is attributed to the abundant surface basic sites as evidenced by results of CO2-TPD. XPS and XAFS provide evidence for the reduction of Ni2+ by Al doping in NiO, which suggest large amounts of O-vacancies present on Ni3Al-HTO. This work is useful to explore feasible routes to improve the performance of desulfurization material for the feed gas purification.

BACKGROUND: A novel semi‐dry method called SDA (spray drying absorption) for the simultaneous removal of mercury (Hg⁰) and sulfur dioxide (SO₂) have been proposed in this article, in which Hg⁰ was initially oxidized by gaseous oxidant (O₃) and liquid oxidant (K₂S₂O₈, H₂O₂, and NaClO₂), after which SO₂ and Hg²⁺ were absorbed by Ca(OH)₂. RESULTS: The effects on different process conditions and additives on Hg⁰ removal were explored at first, and the results indicated that the Hg removal efficiency could be improved by oxidizing or extending the residence time of the liquid phase reaction. When SO₂ and Hg coexist in the atmosphere, additives including oxidants or composite additives were added into the mixed system, and the results indicated that the best removal efficiency of SO₂ and Hg was about 99.5% and 51% respectively. CONCLUSION: Since SO₂ has good water solubility, it would affect the oxidation of Hg and the removal of Hg. When there was nitric oxide (NO) in the atmosphere, a new stable product was generated which contributed to the removal of Hg, and the removal efficiency of SO₂ and Hg was about 99.5% and 57% respectively. © 2020 Society of Chemical Industry

Catalytic oxidation of toluene over noble metal catalysts is a representative reaction for elimination of volatile organic compounds (VOCs). However, to fully understand the activation of molecular oxygen and the role of active oxygen species generated in this reaction is still a challenging target. Herein, MgO nanosheets and single-atom Pt loaded MgO (Pt SA/MgO) nanosheets were synthesized and used as catalysts in toluene oxidation. The activation process of molecular oxygen and oxidation performance on the two catalysts were contrastively investigated. The Pt SA/MgO exhibited significantly enhanced catalytic activity compared to MgO. The oxygen vacancies can be easily generated on the Pt SA/MgO surface, which facilitate the activation of molecular oxygen and the formation of active oxygen species. Based on the experimental data and theoretical calculations, an active oxygen species promoted oxidation mechanism for toluene was proposed. In the presence of H2O, the molecular oxygen is more favorable to be dissociated to generate •OH on the oxygen vacancies of the Pt SA/MgO surface, which is the dominant active oxygen species. We anticipate that this work may shed light on further investigation of the oxidation mechanism of toluene and other VOCs over noble metal catalysts.

Mn-Ni oxides with different compositions were prepared using standard co-precipitation (CP) and urea hydrolysis-precipitation (UH) methods and optimized for the selective catalytic reduction of nitrogen oxides (NOx) by NH3 at low temperature. Mn(2)Ni(1)Ox-CP and Mn(2)Ni(1)Ox-UH (with Mn:Ni molar ratio of 2:1) catalysts showed almost identical selective catalytic reduction (SCR) catalytic activity, with about 96% NOx conversion at 75°C and ~99% in the temperature range from 100 to 250°C. X-ray diffraction (XRD) results showed that Mn(2)Ni(1)Ox-CP and Mn(2)Ni(1)Ox-UH catalysts crystallized in the form of Mn2NiO4 and MnO2-Mn2NiO4 spinel, respectively. The latter gave relatively good selectivity to N2, which might be due to the presence of the MnO2 phase and high metal-O binding energy, resulting in low dehydrogenation ability. According to the results of various characterization methods, it was found that a high density of surface chemisorbed oxygen species and efficient electron transfer between Mn and Ni in the crystal structure of Mn2NiO4 spinel played important roles in the high-efficiency SCR activity of these catalysts. Mn(2)Ni(1)Ox catalysts presented good resistance to H2O or/and SO2 with stable activity, which benefited from the Mn2NiO4 spinel structure and Eley-Rideal mechanism, with only slight effects from SO2.

Novel Mn–Ni spinel nanosheets were investigated for the NH3-SCR of NO at low temperature by urea-hydrolysis (UH) and urea-hydrolysis hydrothermal-synthesis (UHHS), and compared with co-precipitation hydrothermal synthesis (CPHS) and co-precipitation (CP) methods. The optimum molar ratio of Mn/Ni (2 : 1) and urea/(Mn + Ni) (3 : 1) were determined, as also were the suitable hydrothermal temperature (130 °C for 24 h) and further calcination (450 °C for 6 h). An Mn(2)Ni(1)Ox-UHHS catalyst produced a purer spinel-structured NiMn2O4 nanosheet than Mn(2)Ni(1)Ox-UH, both of which showed highly efficient SCR activity (>98% NOx conversion at 100–250 °C) and N2 selectivity (>95% at 85% at

The Urban Heat Island (UHI) caused by building densification greatly impacts the sustainability of urban residents and the environment. Therefore, it is necessary to utilize the envelope space of buildings for green retrofitting so that they can contribute to mitigating the UHI effect. In particular, green retrofitting of existing and historic buildings has become an effective means to improve the resilience of cities in the modernization process. In this study, Vertical Greenery Systems (VGS) were proposed for traditional commercial and residential buildings in Guangzhou, China. Digital Twin (DT) technology was applied to simulate the VGS construction method and irrigation to visualize the process of VGS construction for old commercial and residential buildings. In addition, the building heat and cooling consumption of the three-dimensional greening of the storage room on the ground floor of the arcade-housing and the living room on the top floor were analyzed according to the thermal parameters of different vertical greening types and different material facades. Finally, the modification of the west and south walls as a greening system was identified as the best energy-saving solution, and this finding provided reasonable theoretical support for the energy-saving design of the three-dimensional greening building of the arched house on South Street, a historic building with a combination of commercial and residential buildings.

Energy-saving and efficient monolithic catalysts are hotspots of catalytic purification of industrial gaseous pollutants. Here, we have developed an electrothermal catalytic mode, in which the ignition temperature required for the reaction is provided by Joule heat generated when the current flows through the catalyst. In this paper, Mn/NiAl/NF, Mn/NiFe/NF and Mn/NF metal-based monolithic catalysts were prepared using nickel foam (NF) as the carrier for thermal and electrothermal catalysis of n-heptane. The results indicated that Mn-based monolithic catalysts exhibit high activity in thermal and electrothermal catalysis. Mn/NiFe/NF achieve conversion of n-heptane more than 99% in electrothermal catalysis under a direct-current (DC) power of 6 W, and energy-saving is 54% compared with thermal catalysis. In addition, the results indicated that the introduction of NiAl (or NiFe) greatly enhanced the catalytic activity of Mn/NF, which attributed to the higher specific surface area, Mn

Ce

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.

BACKGROUND: The combined Adsorption‐Nonthermal Plasma Catalytic process (A‐NTP‐C) which is used for decomposition of NOx has become a technical approach of high research value.Many studies have shown that the better the adsorption performance of the catalyst in the A‐NTP‐C process, the higher the conversion of NO. The type of Cu precursors will affect the chemical/physical properties of Cu‐based catalysts, thus influencing the adsorption performance of catalysts. In this study, an ion exchange process was used to prepare Cu/ZSM‐5 catalysts with three Cu precursors, namely copper acetate (AC‐Cu), copper nitrate (N‐Cu) and copper sulfate (S‐Cu). RESULTS: Different Cu precursors led to differences in Cu ion exchange capacity of Cu/ZSM‐5; the Cu content of AC‐Cu/ZSM‐5 was the highest. Furthermore, even with the same Cu content as N‐Cu/ZSM‐5 and S‐Cu/ZSM‐5, the AC‐Cu/ZSM‐5 catalyst showed the best adsorption performance. CONCLUSION: X‐ray photoelectron spectroscopy results indicated that CuO and isolated tetrahedron‐coordinating Cu(II) were the main forms of Cu species on Cu/ZSM‐5. The results of in situ DRIFTs indicated that NO was oxidized by CuO and the generated NO₂ was adsorbed by H⁺ and isolated Cu (II). The AC‐Cu/ZSM‐5 catalysts had the largest amount of tetrahedron‐coordinating isolated Cu (II) and the strongest H⁺ electrophilic ability, giving it the best NOx adsorption performance. The different precursors had little effect on the ZSM‐5 structure, but did cause differences in pore volume, which might influence the adsorption capacity of NOx to some extent. These conclusions provide new ideas and methods for optimizing the adsorption capacity of Cu/ZSM‐5. © 2019 Society of Chemical Industry © 2019 Society of Chemical Industry

The spherical Mn Co spinel catalyst were prepared by (NH4)2CO3-assisted co-precipitation method and were used for the catalytic oxidation of NO at low temperature. The experimental results showed that the optimized Mn0.52Co2.48O4 spinel catalyst, preparing under conditions of Co/Mn molar ratio as 5 and calcination temperature at 450° for 5 h, has the best catalytic activity with about 65% NO oxidation at 150 °C, 80% at 200 °C and 90% at 250 °C, respectively. The main reasons for good NO oxidation activity over Mn0.52Co2.48O4 spinel were attributed to the high surface area of 182.8 m2/g, low apparent activation energy of 30.8 kJ/mol, high content of high surface concentrations of chemisorbed oxygen, Mn4+/Mn3+ and Co2+/Co3+, and the efficient synergetic effect between Co and Mn ions (Co2+ + Mn4+ ↔ Mn3+ + Co3+; Co3+ + Mn2+ ↔ Mn3+ + Co2+). The monodentate nitrite and bridged nitrate species were the important intermediates in the oxidation process of NO to NO2, and the adsorption-reaction pathways were further proposed over Mn Co spinel catalyst.