Bimetallic-MOF-Derived ZnxCo3-xO4/Carbon Nanofiber Composited Sorbents for High-Temperature Coal Gas Desulfurization

Overlooked CO2 emissions induced by air pollution control devices in coal-fired power plants

China's efforts to mitigate air pollution from its large-scale coal-fired power plants (CFPPs) have involved the widespread use of air pollution control devices (APCDs). However, the operation of these devices relies on substantial electricity generated by CFPPs, resulting in indirect CO₂ emissions. The extent of CO₂ emissions caused by APCDs in China remains uncertain. Here, using a plant-level dataset, we quantified the CO₂ emissions associated with electricity consumption by APCDs in China's CFPPs. Our findings reveal a significant rise in CO₂ emissions attributed to APCDs, increasing from 1.48 Mt in 2000 to 51.7 Mt in 2020. Moreover, the contribution of APCDs to total CO₂ emissions from coal-fired power generation escalated from 0.12% to 1.19%. Among the APCDs, desulfurization devices accounted for approximately 80% of the CO₂ emissions, followed by dust removal and denitration devices. Scenario analysis indicates that the lifespan of CFPPs will profoundly impact future emissions, with Nei Mongol, Shanxi, and Shandong provinces projected to exhibit the highest emissions. Our study emphasizes the urgent need for a comprehensive assessment of environmental policies and provides valuable insights for the integrated management of air pollutants and carbon emissions in CFPPs.

Rational Construction of MOF-Derived Porous ZnTiO3/TiO2 Heterostructured Photocatalysts with Remarkable Photocatalytic Performance

TiO2 has been widely used in photodegradation of pollutants, but it suffers from inferior photocatalytic performance under solar light illumination. Thus, novel porous ZnTiO3/TiO2 heterostructured photocatalysts are constructed by hydrothermal and carbonization techniques using ZIF-8 as a sacrificial template. After coating with TiO2, ZIF-8 nanocubes are selectively etched and subsequently coprecipitated with Ti ions during the hydrothermal process. Thereafter, the pores generated from carbonized ZIF-8 provide a large specific surface area and abundant active reaction sites for photocatalysis after annealing, producing stable ZnTiO3/TiO2 nanocomposites. Thus, porous ZnTiO3/TiO2 heterostructured photocatalysts exhibit excellent photocatalytic performance under solar light irradiation due to the boosted electron-hole separation/transfer. The kinetic constant of ZnTiO3/TiO2 nanocomposites (4.66 × 10-1 min-1) is almost 100 and 3.7 times higher than that of self-degradation (4.69 × 10-3 min-1) and TiO2 (1.27 × 10-1 min-1), respectively. This facile strategy provides a deep insight into synthesizing heterostructured photocatalysts with high efficiency in the field of environmental remediation.

Highly Dispersed FeAg-MCM41 Catalyst for Medium-Temperature Hydrogen Sulfide Oxidation in Coke Oven Gas

The traditional hydrolysis-cooling-adsorption process for coke oven gas (COG) desulfurization urgently needs to be improved because of its complex nature and high energy consumption. One promising alternative for replacing the last two steps is selective catalytic oxidation. However, most catalysts used in selective catalytic oxidation require a high temperature to achieve effective desulfurization. Herein, a robust 30Fe-MCM41 catalyst is developed for direct desulfurization at medium temperatures after hydrolysis. This catalyst exhibits excellent stability for over 300 h and a high breakthrough sulfur capacity (2327.6 mgS gcat-1). Introducing Ag into the 30Fe-MCM41 (30Fe5Ag-MCM41) catalyst further enhances the H2S removal efficiency and sulfur selectivity at 120 °C. Its outstanding performance can be attributed to the synergistic effect of Fe-Ag clusters. During H2S selective oxidation, Fe serves as the active site for H2S adsorption and dissociation, while Ag functions as the catalyst promoter, increasing Fe dispersion, reducing the oxidation capacity of the catalyst, improving the desorption capacity of sulfur, and facilitating the reaction between active oxygen species and [HS]. This process provides a potential route for enhancing COG desulfurization.

The Potential of Spent Coffee Grounds @ MOFs Composite Catalyst in Efficient Activation of PMS to Remove the Tetracycline Hydrochloride from an Aqueous Solution

The efficient removal of Tetracycline Hydrochloride (TC) from wastewater, which is a difficult process, has attracted increasing attention. Aiming to synchronously achieve the goal of natural waste utilization and PMS activation, we have combined the MOFs material with waste coffee grounds (CG). The catalytic activity of the CG@ZIF-67 composite in the TC removal process was thoroughly evaluated, demonstrating that the TC removal rate could reach 96.3% within 30 min at CG@ZIF-67 composite dosage of 100 mg/L, PMS concertation of 1.0 mM, unadjusted pH 6.2, and contact temperate of 293.15 K. The ¹O₂ and ·SO₄^- in the CG@ZIF-67/PMS/TC system would play the crucial role in the TC degradation process, with ¹O₂ acting as the primary ROS. The oxygen-containing functional groups and graphite N on the surface of CG@ZIF-67 composite would play a major role in efficiently activating PMS and correspondingly degrading TC. In addition, the CG@ZIF-67/PMS/TC system could withstand a wide pH range (3-11). The application of CG in preparing MOF-based composites will provide a new method of removing emerging pollutants from an aqueous solution.

Rational construction of ZnO/CuS heterostructures-modified PVDF nanofiber photocatalysts with enhanced photocatalytic activity

PVDF/ZnO/CuS photocatalysts with ZnO/CuS heterojunctions were synthesized via electrospinning, hydrothermal, and ion-exchange techniques. As matrix materials, electrospun PVDF nanofibers are easy to be recycled and reused. ZnO nanorods anchored on PVDF nanofiber with high specific surface area provide abundant active reaction sites for photocatalysis. While the loaded CuS nanoparticles as a photosensitizer compensate the low quantum efficiency of ZnO and improve the visible-light photocatalytic efficiency. As a result, the PVDF/ZnO/CuS composited photocatalyst exhibits outstanding photocatalytic performance in exposure to UV and visible light owing to the suppressed recombination of electron-hole pairs and widened visible light absorption range. The kinetic constants of PVDF/ZnO/CuS nanocomposites under UV irradiation (9.01 × 10^-3 min^-1) and visible light (6.53 × 10^-3 min^-1) irradiation were 3.66 and 2.53 times higher than that of PVDF/ZnO (2.46 × 10^-3 min^-1 & 2.58 × 10^-3 min^-1), respectively. Furthermore, PVDF/ZnO/CuS nanocomposites demonstrate excellent robustness in terms of recycling and reuse, which is advantageous in practical applications.