N2 Selectivity Research Articles

TiO2 modified limonite for selective catalytic reduction of NO from cement kiln flue gas with NH3

Limonite was used as a precursor and TiO2 as a modifier to synthesize TiO2/Limonite composites through the wet impregnation method. The influences of the TiO2 doping amount, the calcination temperature on the denitration efficiency and the structure and properties of composites were systematically studied. The results showed that the modified catalyst over the Ti/Fe mass ratio was 0.07 and the calcination temperature was 300°C exhibited excellent catalytic activity, good stability, and remarkable resistance to water and sulfur dioxide within reaction temperature of 100 ∼ 240°C. When NO initial concentration was 0.05 % and gas hourly space velocity (GHSV) was 36,000 h−1 and the reaction temperature was 130°C, the NO conversion efficiency reached 100 %, and the N2 selectivity was 99.6 %. When the catalyst was exposed to 10 %H2O at 150°C, it maintained a 100 % NO conversion efficiency. In the presence of 10 %H2O and 50 ppm SO2 at 200°C, the NO conversion efficiency remained at 100 %. The TiO2/Limonite catalyst possessed improved performance due to the introduction of the anatase TiO2, which led to more lattice defects, weak Lewis acid sites, and higher adsorbed oxygen mobility.

Preparation of Mn/TiO2 catalysts using recovered manganese from spent alkaline batteries for low-temperature NH3-SCR

Black mass (BM) from spent alkaline Zn-MnO2 batteries was used for the first time as a Mn source in the preparation of Mn/TiO2 catalysts for low-temperature NH3-selective catalytic reduction (SCR) of NOx. To recover Mn species and eliminate alkali and Zn species, BM powder underwent DI-water washing, followed by carbothermal reduction. The resulting slags were further dissolved in HNO3, loaded onto TiO2 particles with ball milling, and then subjected to calcination. Nearly 100% of Zn species were removed from the BM via carbothermal reduction at 950 °C for 4 h with 5.0 wt% activated carbon. The resulting catalyst, derived from the treated BM, achieved similar NOx conversion (97%) as the catalyst prepared using a reagent-grade Mn chemical at 160 °C but a higher NOx-to-N2 conversion rate at 78%. The promoted N2 selectivity was attributed to a high Mn4+/Ti ratio and the presence of impurities from BM, such as Fe3+ ions, which enhanced oxidation ability of the catalyst. Conversely, insufficient removal of Zn or carbon additives in the slags led to a decreased Mn concentration, an increased proportion of Mn2+/Mn3+ species, increased surface OH groups, and reduced oxidation ability on the surface, thus reducing NOx conversion and N2 selectivity.

Ammonia nitrogen removal from coal gasification wastewater using a falling-film dielectric barrier discharge reactor: Process optimization and toxicity analysis

The continuous use of coal gasification technology for green energy generation to supplement the dwindling energy reserves generates significant amounts of wastewater containing ammonia nitrogen, posing a significant risk to the finite drinking water sources and aquatic lives. Herein, two falling-film dielectric barrier discharge (DBD) reactors with copper and titanium high-voltage electrodes, respectively, were designed to remove ammonia nitrogen (NH3−N) and chemical oxygen demand (COD) simultaneously from coal gasification wastewater. The operational parameters were screened using the Plackett-Burman design, and the significant parameters were further optimized via the response surface methodology. The results showed that the power parameter significantly influenced NH3-N removal, and COD removal was influenced considerably by power and treatment time. Under the optimum conditions (treatment time = 20.32 min, pH = 3, airflow rate = 1 L/min, power = 116 W, and recirculating flow rate = 50.02 mL/min), a removal ratio of 62.33 % and 37.35 % was achieved for NH3-N and COD for the reactor with the copper electrode, and 67.66 % and 44.90 % for NH3-N, and COD for the reactor with the titanium electrode. Additionally, the concentrations of O3, ·OH, and H2O2 produced by the reactors were quantified, and their crucial roles in the removal process of NH3-N were evaluated. Although smaller concentrations of NO2− and NO3− were detected in the treated wastewater, over 97 % of N2 selectivity encompassed NH3-N removal. Finally, acute phytotoxicity tests were performed, and the results indicated that at 100 mL/L dosage, the treated wastewater from both reactors did not restrict Barbarea verna growth.

Effect of sulfation on the catalytic performance of Mn-Co composite oxide catalyst for the selective catalytic reduction of NOx by NH3

The effect of sulfation on the catalytic performance of Mn-Co composite oxide catalyst for the selective catalytic reduction of NOx by NH3 (NH3-SCR) has been investigated. Different concentrations of SO2 have been used to sulfate Mn-Co composite oxide catalyst. The catalyst sulfated with 30 ppm SO2 showed the widest activity temperature window, over which 80% NOx conversion was obtained in the temperature range of 80–350 °C. The sulfation leads to the appropriate redox property of Mn-Co composite oxide, thus improving the N2 selectivity. Meanwhile, the sulfation contributes to the generation of more Brønsted acid sites, which is crucial for the enhanced activity. In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) demonstrated that the adsorbed NH3 species on both Lewis acid and Brønsted acid sites, monodentate nitrite, bidentate nitrate and cis-nitrite species are the reactive intermediates in the NH3-SCR reaction. This study provides an idea for the regulating the activity temperature window of NH3-SCR catalyst to adapt to its practical application.

Designing ammonia oxidation catalysts via physical mixing of Pt/SiO2 and Cu/ZSM-5

Ammonia (NH3) is emerging as a carbon-neutral fuel alternative; however, its use poses environmental and health risks due to NH3 slip. The NH3-selective catalytic oxidation (NH3-SCO) process, which converts NH3 into N2 and H2O, offers a solution. However, it faces challenges with respect to the formation of byproducts, particularly N2O and NOx. This study focuses on designing NH3-SCO catalysts to enhance low temperature NH3 conversion efficiency while minimizing undesired byproducts. Pt/SiO2 catalysts were synthesized with adjusted Pt particle sizes to improve the NH3-SCO activity and were physically mixed with Cu/ZSM-5 to overcome the low N2 selectivity of Pt-based catalysts by utilizing the selective catalytic reduction (SCR) ability of Cu/ZSM-5. Pt1Cu3 catalyst, a physical mixture of Pt/SiO2 and Cu/ZSM-5 in a 1:3 mass ratio, was found to be the most effective, achieving complete NH3 oxidation at 250 ℃ while maintaining a high N2 selectivity of approximately 80%. Further investigation revealed that the performance of the Pt1Cu3 catalyst was significantly influenced by the arrangement and physical proximity of the Pt/SiO2 and Cu/ZSM-5 catalysts, with a closely contacted mixture showing synergistic effects that enhanced activity and selectivity. These results suggest that the Pt1Cu3 catalyst offers a promising solution for NH3 emission control by utilizing a balanced approach that combines SCO and SCR reactions.

Design of dual-ligand coordination in metal organic frameworks for breaking the seesaw effect between de-NOx activity and N2 selectivity

In the selective catalytic reduction (SCR) of NOx with NH3, a catalyst usually exhibits a seesaw effect on de-NOx activity and N2 selectivity at low temperatures. Herein, we designed metal-organic frameworks (MOFs) with dual-ligand coordination to regulate the electronic and morphological structure for a breakthrough of the seesaw effect. The developed catalyst attained a noteworthy NOx conversion exceeding 90% within 60–330 ℃ with increased N2 selectivity. The dual-ligand coordination leads to more defects and a more uniform electron distribution for delocalization of electrons, thereby improving de-NOx activity. Furthermore, the dual-ligand coordination manifests a Si-O-Mn bond for amplifying both de-NOx activity and thermal stability. Additionally, the dual ligands and Mn produce a hollow sea-urchin-like morphology with more exposed active sites for concentrating reactants and intermediates to improve electron transfer efficiency in N2 selectivity. This work clarifies the mechanism of dual-ligand regulation for electron-morphology to simultaneously enhance de-NOx activity and N2 selectivity.

In-situ interzeolite transformation synthesis Cu-SSZ-13 from coal fly ash-derived zeolite for NH3-SCR reaction

Cu-SSZ-13 catalyst has excellent performance for removing NOx. In this study, the in-situ inter-zeolite transformation (IZT) method was proposed to prepare Cu-SSZ-13 catalyst. The coal fly ash-derived zeolite acted as a raw material rather than the chemical silicon and aluminum source. A series of catalysts were prepared using the in-situ IZT method with different ratios of the two template agents. The NO conversion of Cu-SSZ-13 catalysts was above 90 % within the temperature range of 200–700 °C, whereas the N2 selectivity was maintained at about 100 %. The as-synthesized catalysts had higher conversion rates for Si and Al, higher copper loading and more isolated Cu2+. The selective catalytic reduction (SCR) reaction mechanisms of Cu-SSZ-13 catalyst prepared using the in-situ IZT method followed both the Eley-Rideal (E-R) mechanism and the Langmuir-Hinshelwood (L-H) mechanism, though it was mainly based on the E-R reaction. In this study, the Cu-SSZ-13 catalysts were synthesized using coal fly ash based zeolite in one step. This study further improved the synthesis process route from coal based solid waste to SCR catalyst, shortened the preparation cycle, and improved catalyst performance.

Revealing the roles of Zr on enhanced H2-SCR performances on Pt/TiO2 catalyst

The development of Hydrogen Internal Combustion Engine (H2-ICEs) to replace conventional fuel engines is expected to be an effective way to reduce CO2 emissions, but some NOx emitted from the H2-ICEs still should be eliminated by the selective catalytic reduction of NOx with H2 (H2-SCR). Large amount of platinum oxide existed on Pt/TiO2 leads to its low H2-SCR activity. In contrast, the Zr-modified Pt/TiO2 catalysts exhibit a higher NOx conversion and N2 selectivity in a wider temperature window (100–180 °C) than those of Pt/TiO2. The appropriately weakened strong interaction between Pt and TiO2 by Zr induces more Pt0 species, which are active sites for the activation of NOx and H2 in H2-SCR reaction. More oxygen vacancies caused by the formation of Zr-Ov-Ti3+ bands involve in the activation of NOx and the adsorption of nitrates (NOx−) species. Furthermore, in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTs) demonstrates that Pt/ZrxTi1-x catalysts possess more adsorbed NOx− species and a faster reduction rate for them. Monodentate and bridged nitrates are considered to be more reactive with H2 than bidentate nitrates at relatively low temperatures. This work provides directions for the development of high-performance H2-SCR catalysts and the modulation of the conversion temperature.

In situ DRIFTS study and mechanism analysis of selective catalytic reduction of NOx by NH3 over ions doping MnCeOx/GR catalyst

The present study demonstrates an innovative approach of doping MnCeOx/GR catalyst with three transition metal ions, namely Fe3+, Co3+, and Ni2+. Subsequently, the catalyst exhibiting superior performance was carefully selected. Meanwhile, the micro-reaction process of MnCeOx/GR and ion-doped MnCeOx/GR catalysts were established by in situ DRIFTS. The phenomena occurred in the experiment process were thoroughly examined through the application of various characteristic analysis, for instance, XRD, Raman, BET, XPS, H2-TPR, and NH3-TPD to analyze that Co3+ doping had a good improvement of activity and N2 selectivity on MnCeOx/GR catalyst at low temperature. This was evidenced by the activity test experiments, which revealed that CoMnCeOx/GR catalyst has the highest NO conversion within 150–225 °C temperature range, surpassing 90 %. Our findings showed that Co3+ doping not only enhanced redox capability and surface acidity, but also raised the relative Mn4+, Ce3+, and Oα content compared to MnCeOx/GR catalyst, which eventually contributed that the reactant molecules can be more effectively adsorbed onto the catalyst, thereby enhancing activation of NH3 and O2, thus improving efficiency of CoMnCeOx/GR catalyst. Additionally, it was proved that the Eley-Rideal and Langmuir-Hinshelwood mechanisms co-existed on CoMnCeOx/GR catalyst in a competitive way by in situ DRIFTS test.

Tandem photocatalysis of nitrate to nitrogen on Cu@CN/TiOx S-scheme heterojunction

The persistent challenge of nitrate (NO3–) pollution in water systems, profoundly impacting ecosystems and human health, demands effective remediation strategies. Here, we present an innovative S-scheme Cu@CN/TiOx heterojunction for high-efficiency photocatalytic denitrification (PCDN). Evaluation of its performance demonstrates exceptional NO3– removal efficiency (99.5%) and remarkable N2 selectivity (95.5%), with 13.7 and 4.1 times higher rate constants of NO3– removal than the individual Cu@CN and TiOx components. Notably, this catalyst exhibits impressive stability across multiple cycles, maintaining consistent high conversion rates and selectivity. Mechanistic insights unveiled a tandem reaction pathway where Cu@CN selectively reduced NO3– to NO2–, followed by the TiOx-mediated CO2•– generation, enabling highly selective NO2– to N2 conversion. This unique catalytic system, featuring spatially separated redox-active sites, presents a promising avenue for efficient, selective, and stable denitrification processes, offering significant potential in addressing water pollution challenges and advancing tandem catalytic systems.

Optimized synthesis of Fe-doped Ohmic Schottky heterojunctions for efficient NO3− photocatalytic reduction to generate N2

Capacitive Fe-doped Ni2P(Fe2xNi2(1-x)P) is synthesized via the modified solvothermal method to form Ohmic Schottky heterojunctions with monolayer Ti3C2 (MLTC). The composite (10 % 0.1FNP/CdS-2 % MLTC) achieved a high hydrogen evolution rate (HER) of 19.18 mmol h−1 with a 50 mg sample. In a mere span of 3 h, an impressive NO3− reduction of 0.42 mg/L was achieved, accompanied by an exceptional 92 % N2 selectivity. Quantum efficiency (QE) can reach 56.22 % (λ = 475 nm) by adding 0.1FNP and MLTC. In contrast to previous catalysts, the QE of visible light after 500 nm has been improved to 45.2 % (λ = 500 nm) or 36.4 % (λ = 550 nm). The significant enhancement of HER and NO3− reduction is attributed to the enhanced adsorption of oxygen-containing reactants, the lowering of the reduction overpotential, further enhanced separation efficiency of photogenerated carriers through the ohmic Schottky heterojunction after iron doping. Additionally, the observed capacitor-like nature of 0.1FNP is also an essential factor for the enhanced reduction ability of the composites.

Temperature-driven dynamic evolution process of Ag species on silver-loaded Zr0.2Sn0.8O2 catalyst for selective catalytic oxidation of ammonia

Silver-based catalysts are extensively utilized in the selective catalytic oxidation of ammonia (NH3-SCO). However, enhancing low-temperature activity often causes a decline in N2 selectivity, presenting a substantial challenge in balancing activity and N2 selectivity. In this work, we introduced zirconium into the SnO2 support, resulting in a significant enhancement of low-temperature activity by 200 °C for the Ag/Zr0.2Sn0.8O2 catalyst; yet, this also led to the formation of N2O at low temperatures and NOx at high temperatures. Characterizations such as XPS and in situ DRIFTS revealed that the dynamic changes of silver species driven by temperature had a profound impact on the reaction mechanism and guided the formation of different products. Below 200 °C, the predominance of Ag+ directed the imide mechanism, with the –HNO species being the key intermediate leading to the production of N2O. Above 300 °C, Ag0 became dominant, favoring the internal selective catalytic reduction (i-SCR) mechanism and the production of NOx. This work provides novel insights into improving N2 selectivity of Ag-based catalysts and contributes to a deeper understanding of the reaction mechanisms.

Phosphotungstic Acid as a Dechlorination Agent Collaborates with CeO2 for Synergistic Catalytic Elimination of NOx and Chlorobenzene.

The development of efficient technologies for the synergistic catalytic elimination of NOx and chlorinated volatile organic compounds (CVOCs) remains challenging. Chlorine species from CVOCs are prone to catalyst poisoning, which increases the degradation temperature of CVOCs and fails to balance the selective catalytic reduction of NOx with the NH3 (NH3-SCR) performance. Herein, synergistic catalytic elimination of NOx and chlorobenzene has been originally demonstrated by using phosphotungstic acid (HPW) as a dechlorination agent to collaborate with CeO2. The conversion of chlorobenzene was over 80% at 270 °C, and the NOx conversion and N2 selectivity reached over 95% at 270-420 °C. HPW not only allowed chlorine species to leave as inorganic chlorine but also enhanced the Bro̷nsted acidity of CeO2. The NH4+ produced in the NH3-SCR process can effectively promote the dechlorination of chlorobenzene at low temperatures. HPW remained structurally stable in the synergistic reaction, resulting in good water resistance and long-term stability. This work provides a cheaper and more environmentally friendly strategy to address chlorine poisoning in the synergistic reaction and offers new guidance for multipollutant control.

Promoting effect of polyoxometallic acid modification on the NH3-SCR performance of Mn-based catalysts

The strong oxidation capabilities of Mn sites render Mn-based catalysts showing high activities of selective catalytic reduction (SCR) at temperatures < 250℃, but simultaneously lead to the generation of by-product N2O with strong greenhouse effect. The activity-N2-selectivity trade-off was a prevalent observation in the development of Mn-based SCR catalysts. Here, a polyoxometallic acid enhancement strategy was devised to simultaneously promote the N2 selectivity and low-temperature SCR (LT-SCR) activity of Mn-based metal oxide catalysts, where the introduction of uniformly dispersed phosphomolybdic acid (HPMo) tuned the oxidation capabilities and enhanced NH3 adsorption-storage capability of catalysts. The combination of transient reaction, in-situ DRIFTS analysis and DFT calculations revealed that the main origin of N2O on the Mn-based catalysts was the deep oxidation of NH3, which was inhibited by the interaction between HPMo and Mn sites. Additional NH3 molecules adsorbed by the abundant acid sites supplied by HPMo further facilitated the SCR reaction. This strategy could guide the design of high-activity and high-selectivity LT-SCR catalysts for industrial denitration.

Effect of samarium doping on the activity and sulfur resistance of Ce/MnFeOx catalyst for low-temperature selective catalytic reduction of NOx by ammonia

The self-made MnFeOx catalysts doped with cerium and samarium were prepared by impregnation method for low-temperature selective catalytic reduction by NH3. In this work, the surface properties of the series of MnFe-based catalysts were studied. The results indicate Sm-modified catalyst have superior low-temperature SCR activity; NOx conversion maintained at nearby to 100% at 90–240 °C. In addition, The N2 selectivity of Sm doping remains above 80% in the range of 60–150 °C. In SO2 poisoning test, the NOx conversion can be remained >90% after 10 h of reaction. The XPS, NH3-TPD and H2-TPR results show the catalyst with Sm doping enhances the acid sites and oxidation catalytic sites of mixed oxides serves for improving oxygen vacancies and transfer electrons. In situ DRIFTS results show that NOx is more easily adsorbed on the surface after Sm doping, which provided favorable conditions for the NH3-SCR reaction to proceed. The reaction at the catalyst surface will follow the L-H reaction mechanism by transient reaction test.

Mechanistic insights into the influence of preparation methods and Fe3+ doping on the low-temperature performance of MnCeOx catalyst for NH3-SCR reaction

Aiming to polish up the denitrification efficiency and N2 selectivity for MnCeOx catalyst at low temperature, an array of Fe3+-doped MnCeOx catalysts were synthesized through innovative approaches: the citric acid method (FeMnCeOx-CA) and CTAB-assisted template method (FeMnCeOx-ST). However, the catalysts prepared by CTAB-assisted template method (MnCeOx-ST and FeMnCeOx-ST catalysts) did not exhibit an excellent low-temperature activity compared with the catalysts made by citric acid method (MnCeOx-CA and FeMnCeOx-CA catalysts) below 300 °C. Therefore, an in-depth investigation of underlying impact of citric acid method and Fe3+ doping on MnCeOx catalyst was thoroughly implemented. We finally found that the main function of citric acid is to enhance the internal electron transfer of the catalyst by facilitating the mutual conversion between active components, particularly Mn4+/Mn3+, thereby improving the denitrification activity of FeMnCeOx-CA catalyst at low temperature. Further, the NH3-SCR performance of FeMnCeOx-CA exceed 90 % NOx conversion within 75–150 °C, and it can be reached 94 % NOx conversion at 125 °C, which was almost 10 % higher than that of MnCeOx-CA catalyst. Moreover, the N2O formation of FeMnCeOx-CA is significantly suppressed at temperatures ranging from 125-200 °C, exhibiting a higher N2 selectivity compared to MnCeOx-CA. Besides, solid solution structure of −Ce-O-Mn-O-Fe- formed after Fe3+ doping in MnCeOx catalyst strengthened surface acidity and redox ability over FeMnCeOx-CA catalyst, promoting NH3 adsorption and activation. On the other hand, the FeMnCeOx-CA catalyst exhibits the highest content of Ce3+ and Mn4+, facilitating oxygen vacancies formation and redox capacity, thereby promoting the key intermediates generation in the microscopic NH3-SCR reaction process. Finally, a reasonable Langmuir-Hinshelwood mechanism and detailed reaction pathways of NH3-SCR reaction existed on FeMnCeOx-CA catalyst were also proposed.

Mechanism of CO + NH3-coupled removal of NO from Fe/AC catalysts at medium and low temperatures

Catalysts with different mass ratios (Fe: AC = 7.5, 10.0, and 12.5) were prepared using the equal-volume impregnation method. The 12.5Fe/AC catalyst exhibited the highest NO removal activity and best N2 selectivity at any given temperature. Furthermore, NO removal was mediated by redox reactions between Fe2+ and Fe3+ and dominantly occurred at the Fe2+ active sites. As the loading amount of active metal (Fe) increased, the diffraction ring gradually diffused, and the number of Fe oxide crystals, number of oxygen-containing functional groups, and content of chemically adsorbed oxygen increased. Chemically adsorbed oxygen plays a major role in NO removal. The NO removal mechanism of the Fe/AC catalyst is dominated by physical adsorption and the Langmuir–Hinshelwood mechanism at low temperatures and by the Eley–Rideal mechanism at medium and low temperatures.

Application of metal-organic frameworks for CO2 capture

The emission of carbon dioxide (CO2) is gradually increasing, and CO2 adsorption from post-combustion processes in thermal power plants could be a viable option. As a solid adsorbent for CO2 capture, metal-organic frameworks (MOFs) have higher selectivity and capacity for flue gas. Compared with traditional adsorbents, calgary framework 20 (CALF-20) that belongs to a zinc-based MOFs, efficiently captures CO2 from flue gas and is affordable and durable also, which lays the foundation for its large-scale production. This article will introduce the overall idea of CO2 adsorption, the structure of CALF-20, selectivity for N2 and H2O, competitive adsorption with H2O-CO2 and durability, and verify the excellent performance of CALF-20 with experimental results. In addition, the possibility of mass production was also shown. Specifically, CALF-20 is not as difficult to large scaling produce as other MOFs. In fact, its large-scale industrial production is feasible with its advantages of low cost, high yield, stability, environmentally friendly and safety.

Enhancing CO2/N2 and CO2/CH4 separation in mixed matrix membrane: A comprehensive study on Pebax®1657 with SSMMP/IL for improved efficiency

AbstractMixed matrix membranes (MMMs) have been proposed as a solution to surmount Robeson's trade‐off curves and have demonstrated efficacy in gas separation processes, particularly for CO2 capture. In this study, MMMs based on Pebax®1657 were obtained utilizing synthetic silico‐metallic mineral particles (SSMMP) functionalized with ionic liquids (ILs). The objective was to attain enhanced CO2 separation performance, thereby showcasing the potential to mitigate the environmental repercussions of industrial processes that entail greenhouse gas emissions. For membrane production, an ethanol/water mixture was used as solvent, with the SSMMP/IL content varying from 0.5 to 20% by weight of the polymer. The primary aim of this study was to assess the effect of filler addition on permeability and selectivity for CO2, CH4, and N2. Comprehensive analyses, including SEM, FTIR, TGA, DSC, and DMA were conducted to evaluate the properties of the produced membranes. Gas permeability and ideal selectivity were measured at 25°C and different pressures, ranging from 1 to 7 bar. Characterization results demonstrate that the glass transition temperature (Tg) of MMMs increased compared to pure Pebax®1657, indicating that the addition of SSMMP/IL reduces the flexibility of the PEO chains, forming a rigid interface at the polymer/filler, which may enhance selectivity. This effect, corroborated by gas permeation, was observed for both CO2/N2 and CO2/CH4. For CO2/N2, the highest selectivity was achieved at lower filler concentrations, gradually decreasing as the filler load increased. MMM‐0.5 wt% achieved the highest selectivity of 91.96. The membrane CO2 permeability rose with an elevated filler content, rising from 84.21 for pure Pebax®1657 to 192.17 Barrer for MMM‐20 wt% at 4 bar. The permeability results were influenced by the gas diffusion coefficients of the MMMs, which increased with increasing SSMMP/IL content. The effect of feed pressure on MMM‐5 wt% was also assessed, revealing that CO2 permeability increased with increasing pressure, from 126.72 Barrer at 1 bar to 165.56 Barrer at 7 bar. This work showcased the viability of MMMs incorporating SSMMP/IL for industrial use, as they displayed separation capabilities that exceeded the 2008 Robeson upper bound.Highlights Mixed matrix membranes based on Pebax®1657 and SSMMP‐20%‐[bmim][Tf2N] were prepared. CO2 permeability of the MMMs was increased by 128% and CO2/N2 selectivity by 83%. Higher CO2 pressures increase MMMs permeability. The obtained MMMs have separation performances above the Robeson upper Bound.

Design of Fe-based metal organic framework derived catalysts: Remediation of nitrate contamination and action in polluted surface water

Removing nitrate from surface water is a constant challenge due to its high stability. While electrochemical treatment, a clean and renewable energy source, is promising, most strategies focus solely on energy conversion without considering treatment efficiency and practical application prospects. In this study, a Fe-based MOF derived material MC was synthesized by combining the process of hydrothermal and pyrolysis using Fe-MOF as the raw material to investigate the viability of nitrate reduction. The MC electrode exhibits 91.3 % NO3- removal and 44.9 % current efficiency in 180 min. The selectivity of ammonia is 90.6 % without Cl- and the selectivity of N2 is 89.9 % with Cl-. The excellent behavior of MC is attributed to the layered structure of dispersed Fe-based nanocluster and interconversion of Fe three valence states, which are conducive to mass transfer and electron transfer, respectively. The Layered Fe-based electrode material MC is a cost-effective, high-efficiency and stabilized electrode catalyst capable of treating water in a wide pH range and broad hardness. It maintained excellent stability over ten cycles and was used to remove nitrate, TN, and COD from polluted surface water, proving to be an environmentally friendly option for the deep purification of polluted surface water.