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Hierarchical AlOOH@reduced graphene oxide (RGO) hybrids are synthesized by an anti-solvent process with the assistance of supercritical carbon dioxide (scCO 2 ) fluid due to its high diffusivity and low viscosity. The presence of RGO allows the uniform and vertical assembling of AlOOH nanosheets to form hierarchically nanostructured hybrids with a large specific surface area of 513 m 2 g −1 . The favorable structure with numerous mesopores provides sufficient active sites for the adsorption of fluoride species, leading to a maximum adsorption capacity of 118.7 mg g −1 , which is among the best performances of aluminum based adsorbents. Compared to neat AlOOH, it is interesting that AlOOH@RGO hybrid exhibits a much better defluoridation capacity at lower initial concentrations of fluoride ions, which is quite valuable when considering the low fluoride ion concentrations in contaminated groundwater. The stable and robust hierarchical structure afforded by covalent bonding between AlOOH and RGO further endows the hybrid as a promising adsorbent for practical treatment of wastewater due to its excellent fluoride adsorption capacity and ease of separation from aqueous solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • The novel in-situ gas sampling provides 2D spatial maps of gas product compositions. • The CO 2 conversion drops significantly in the afterglow due to recombination. • Dissociation dominates in the plasma, while recombination prevails in the afterglow. • Afterglow quenching considerably increases the CO 2 conversion and energy efficiency. Warm plasma offers a promising route for CO 2 splitting into valuable CO, yet recombination reactions of CO with oxygen, forming again CO 2 , have recently emerged as critical limitation. This study combines experiments and fluid dynamics + chemical kinetics modelling to comprehensively analyse the recombination reactions upon CO 2 splitting in an atmospheric plasmatron. We introduce an innovative in-situ gas sampling technique, enabling 2D spatial mapping of gas product compositions and temperatures, experimentally confirming for the first time the substantial limiting effect of CO recombination reactions in the afterglow region. Our results show that the CO mole fraction at a 5 L/min flow rate drops significantly from 11.9 % at a vertical distance of z = 20 mm in the afterglow region to 8.6 % at z = 40 mm. We constructed a comprehensive 2D model that allows for spatial reaction rates analysis incorporating crucial reactions, and we validated it to kinetically elucidate this phenomenon. C O 2 + M ⇌ O + C O + M and C O 2 + O ⇌ C O + O 2 are the dominant reactions, with the forward reactions prevailing in the plasma region and the backward reactions becoming prominent in the afterglow region. These results allow us to propose an afterglow quenching strategy for performance enhancement, which is further demonstrated through a meticulously developed plasmatron reactor with two-stage cooling. Our approach substantially increases the CO 2 conversion (e.g., from 6.6 % to 19.5 % at 3 L/min flow rate) and energy efficiency (from 13.5 % to 28.5 %, again at 3 L/min) and significantly shortens the startup time (from ∼ 150 s to 25 s). Our study underscores the critical role of inhibiting recombination reactions in plasma-based CO 2 conversion and offers new avenues for performance enhancement. [ABSTRACT FROM AUTHOR]

• Torrefaction condensate (TC) was used for acidification of CaO sorbent. • TC-modified sorbents exhibited excellent cyclic stability over cycles. • Carbon deposition was introduced to sorbents during calcination under N 2 atmosphere. • The introduced carbon deposition acted as overlay and hindered CaO grain sintering. • Increasing torrefaction temperature and TC dosage leaded to more carbon deposition. In this work, the organic acid-rich torrefaction condensate (TC) from biomass torrefaction process was attempted to replace commercial acetic acid (AC) for acidification treatment of CaO sorbent to improve its CO 2 capture performance during calcium looping cycles. The results showed that TC-modified sorbents exhibited a much slower carbonation reactivity decay than the AC-modified one over the cycles. According to the results of characterizations (thermal decomposition, morphology, phase composition, and N 2 adsorption), the enhanced cyclic stability was probably due to the presence of carbon deposition from the decomposition of heavy tar in TC, which might act as a spacer and protective overlay to slow down the sintering of CaO particles. In addition, more carbon deposition could be dispersed in-situ into the TC-modified sorbents by increasing torrefaction temperature and TC addition amount, resulting in more thorough carbon deposition overlay and better sintering resistance. However, excessive carbon deposition (>50 wt%) leaded to slightly lower carbonation conversions and rates in the first two or three cycles. But this deficiency would disappear in subsequent cycles, as some carbon deposition was consumed by the carbon dioxide released during calcination. And the carbonation conversion of TC-modified sorbent with a carbon deposition content of 69.1 wt% was still as high as 81.5% after 10 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical porous Mg-MOF-74 was synthesized by weak coordination of Cl−. • The mesoporous content of hierarchical porous Mg-MOF-74 reached 34.90%. • The CO 2 saturated adsorption capacity increased by 15% at ambient pressure. • The IAST selective adsorption performance of CO 2 /N 2 increased by 20 times. • The adsorption capacity and rate of low pressure were improved. Adsorbents with high adsorption capacity and high selectivity are crucial for carbon capture, utilization and storage (CCUS) technology applied to industrial flue gas to reduce carbon emissions. In this paper, a defect-rich hierarchical porous Mg-MOF-74 was synthesized successfully with MgCl 2 ·6H 2 O used as a metal source considering that the weak coordination of Cl− may interfere with the normal coordination process of metal centers and organic ligands, which causes the formation of crystal defects. Through the analysis of a series of characterizations, ligand deletion of Mg-MOF-74 prepared with MgCl 2 ·6H 2 O was confirmed, and the deleted ligand was estimated to be approximately 20% compared with the traditional Mg-MOF-74 prepared with Mg(NO 3) 2 ·6H 2 O, which led to mesopores accounting for 36.9%, and the width of mesopores reached 13.1 nm. Compared with traditional Mg-MOF-74, the adsorption heat of CO 2 at zero load of the defect-rich hierarchical porous Mg-MOF-74 increased from 36 kJ·mol−1 to 46 kJ·mol−1, and the saturated adsorption capacity of CO 2 under ambient pressure was improved by 15%. Interestingly, the IAST selective adsorption performance of CO 2 /N 2 was increased by 20 times. Compared with the saturated adsorption capacity for traditional Mg-MOF-74, the equivalent adsorption capacity of hierarchical porous Mg-MOF-74 only needs 17 kPa, indicating that it is suitable for carbon capture operation in a real flue environment. Calculations of density functional theory (DFT) confirmed that the active site of the hierarchical porous Mg-MOF-74 has a lower adsorption energy with CO 2 due to the presence of defects, which is regarded to play a key role in improving the CO 2 capture performance. [ABSTRACT FROM AUTHOR]

Two Ag-MOCPs with different dimensional electron transfer Channels were used for electrocatalytic conversion CO 2 to CO. [Display omitted] • New Ag-MOCP materials for CO 2 RR electrocatalysts were synthesized. • CO 2 -to-CO conversion was boosted with the regulation of the electron transfer channel. • The FE CO for Ag-MOCP-2 with multi-dimensional electron transfer channels is higher than that for Ag-MOCP-1 with single channel at most given potentials. • The mechanism of its reaction was further explored by DFT calculation. Although, electrons transfer plays an important role in achieving the electrocatalytic CO 2 reduction reaction (CO 2 RR), it is scarce to regulate the electron transfer channels for enhancing the performance of CO 2 RR via rational design. Here, based on different solvothermal conditions, two metal–organic coordination polymers (MOCPs, Ag-MOCP-1 and Ag-MOCP-2) electrocatalyst for CO 2 RR were obtained by the same Ag ions and 5-phenyltetrazolium ligands. Single crystal X-ray diffraction showed Ag-MOCP-2 with intra-&inter-layer C H···π and π···π interactions, while Ag-MOCP-1 with intra-layer π···π interactions. The intra-&inter-layer π interactions in Ag-MOCP-2 makes it show multi-dimensional electron transfer channels, which enable Ag-MOCP-2 with higher electron conductivities and lower band gap than Ag-MOCP-1. And the Faradaic efficiency of CO for Ag-MOCP-2 with 78.3 % is higher than that for Ag-MOCP-1 with 69.1 % at −1.08 V vs RHE, and the maximum difference can reach 22 % at −1.48 V vs RHE. Based on the same central metal and organic ligands of the two MOCPs, we believe that multi-dimensional electron transfer channels make a predominant contribution for improving CO 2 RR performance in this work. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe x Mn y mixed oxide catalysts with various Mn/Fe + Mn were prepared by co-precipitation. • Mn species enters into Fe 2 O 3 or Fe species, into MnOx, to form Fe-O-Mn structure. • Fe-O-Mn promotes the redox and acidity of Fe 2 O 3 , and activation of Fe-OH with O 2. • Fe 2 O 3 with Fe-O-Mn is active and stable in the oxidation of chlorinated aromatics. • No chlorination product is detected over Fe x Mn y catalysts within 1 ppm limitation. Fe x Mn y mixed oxide catalysts prepared by co-precipitation method are applied in catalytic combustion of chlorobenzene (CB) and 1,2-dichlorobenzene (1,2-DCB). Characterization shows that Mn species of Fe 9 Mn 1 highly disperse into α-Fe 2 O 3 as Fe-O-Mn structure. With the increase in Mn content, a part of Mn is separated as MnO 2 and α-Mn 2 O 3. Fe-O-Mn structure greatly increases the acidity (especially for strong acid) and reducibility of α-Fe 2 O 3. In CB and 1,2-DCB oxidations, Fe x Mn y catalysts are active, of which Fe 9 Mn 1 catalyst presents the highest activity. At 5% – 20% O 2 and 500 – 2000 ppm 1,2-DCB at space velocity of 15,000 mL g-1h−1, the apparent rates at 300 °C over Fe 9 Mn 1 are estimated to be 0.056 – 0.112 μmol min−1 m−2, and the temperatures needed for 50% and 90% conversions are 294 – 342 °C and 346 – 375 °C, respectively. High availabilities of surface oxygen and acid sites are related to effective Cl removal in aid of active hydroxyls produced during the reaction (confirmed by in situ FT-IR tests), which are responsible for high activity of Fe 9 Mn 1 catalyst. For the catalysts with MnO 2 and Mn 2 O 3 domains on the surface, Cl strong adsorption results in their deactivation. Moreover, Fe 9 Mn 1 catalyst shows high stability at 350 °C on feed stream containing 1000 ppm 1,2-DCB within 600 min duration or for five runs. The selectivity for CO/CO 2 approaches 98% or higher and no chlorination products are detected within FID limitation (1 ppm) under the above mentioned broad reaction conditions, which are highly desirable for industrial application. [ABSTRACT FROM AUTHOR]