Zichuan Ma

Methane pyrolysis offers a CO2-free pathway to hydrogen production; however, its commercial deployment remains hindered by a stoichiometric constraint: each kilogram of H2 co-produces three kilograms of solid carbon, which rapidly deactivates the catalyst. Conventional strategies aiming to extend catalyst lifetime are therefore fundamentally incompatible with this inherent stoichiometric constraint. This perspective advocates a paradigm shift: rather than mitigating carbon deposition, we strategically harness it. By designing iron-loaded char catalysts whose spent form is an intimately mixed Fe/C composite suitable for potential use as metallurgical feedstock in steelmaking, we recast catalyst deactivation from an operational failure into a value-capturing endpoint. Experimental results demonstrate that the spent ASC/Fe@C composite exhibits CO2 gasification reactivity markedly superior to that of commercial metallurgical coke. Onset occurs at a temperature approximately 150 °C lower, and conversion reaches 70.7% at 900 °C compared to just 6.5% for coke. This integration of catalytic function with end-of-life value provides a pathway to couple clean hydrogen production with the steel industry. The steel industry, which consumes billions of tons of carbonaceous feedstocks annually, represents a suitable large-scale destination for methane pyrolysis’s million-ton-scale solid carbon output, providing a potential sink for this carbon stream pending quantitative techno-economic validation. Consequently, this approach establishes a cross-sectoral circular carbon economy, potentially eliminating the need for energy-intensive catalyst regeneration while simultaneously advancing steel decarbonization.

Methane catalytic pyrolysis for hydrogen production is hindered by rapid catalyst deactivation due to carbon deposition—a long-standing technical bottleneck. This study proposes and experimentally validates an alternative pathway that reinterprets catalyst deactivation not as failure, but as an in situ synthesis step for a high-value metallurgical composite feedstock, thereby enabling full upcycling of the spent catalyst. An iron-based catalyst supported on industrial metallurgical coke (Fe/Coke) exhibits self-activation behavior during methane pyrolysis. Under optimized conditions (900 °C and CH4 flow rate of 10 mL·min−1), methane conversion increases progressively with time, reaching 93% within 7 h and delivering a hydrogen yield of 9.94 mmol·gcat−1·h−1. Multi-scale characterization demonstrates that self-activation arises from reaction-induced structural evolution: α-Fe particles undergo carburization to Fe3C, concurrent particle refinement from several hundred nanometers to tens of nanometers, and in situ deposition and graphitization of carbon to form a Fe3C@C core−shell architecture with an open mesoporous structure. Kinetic analysis reveals a marked decrease in apparent activation energy, from 166.6 kJ·mol−1 initially to 36.5 kJ·mol−1 after 3 h of reaction. DFT calculations further confirm that the Fe3C surface lowers the C−H bond dissociation barrier to 0.594 eV, substantially below that of α-Fe (0.735 eV), through collective charge redistribution mediated by the Fe−C hybridization network. The resulting composite, Fe/Coke@C, exhibits enhanced CO2 gasification reactivity relative to industrial metallurgical coke, suggesting potential for reuse as a steelmaking feedstock. Preliminary techno-economic analysis indicates that, at a 10 kg H2·h−1 scale, the process achieves a net profit margin of approximately 25.8%, although this estimate is based on laboratory-scale data and requires further validation at a pilot scale. This study presents an approach that reinterprets catalyst deactivation as a potential resource integration step for concurrent green hydrogen production and sustainable metallurgical feedstock supply.

The recovery and control of volatile organic compounds (VOCs) have gained significant attention. Supported sulfonic acid materials show potential in converting aromatic VOCs into non-volatile sulfonic acid derivatives. However, their effectiveness is closely tied to the anchoring state of the sulfonic acid groups. In this study, two supported sulfonic acids, SSA@CdO and SSA@CaO, were synthesized via the respective reactions of CdO and CaO with chlorosulfonic acid to investigate how the properties of the supports influence sulfonic acid anchoring and reactivity toward o-xylene. Comprehensive characterization and performance tests revealed that sulfonic acid groups on CdO were covalently bonded, forming positively charged sites ([O_0.5Cd–O]^ɗ−–SO₃H^ɗ+) with high loading (9.7 mmol/g), enabling excellent o-xylene removal (≥95.6%) and adsorption capacity (51.67–91.59 mg/g) at 130–150 °C. In contrast, ion-paired bonding on CaO formed negatively charged sites ([O_0.5Ca]⁺:OSO₃H⁻), which were inactive in electrophilic sulfonation. This work provides new insights for enhancing supported sulfonic acid materials in VOC treatment.

The recovery and abatement of volatile organic compounds (VOCs) have received increasing attention due to their significant environmental and health impacts. Supported sulfonic acid materials have shown great potential in converting aromatic VOCs into their non-volatile derivatives through reactive adsorption. However, the anchoring state of sulfonic acid groups, which is closely related to the properties of the support, greatly affects their performance. In this study, two supported sulfonic acid materials, SZO and SMO, were prepared by treating ZrO₂ and MgO with chlorosulfonic acid, respectively, to investigate the influence of the support properties on the anchoring state of sulfonic acid groups and their reactive adsorption performance for o-xylene. The supports, adsorbents, and adsorption products were extensively characterized, and the reactivity of SZO and SMO towards o-xylene was systematically compared. The results showed that sulfonic acid groups are anchored on the ZrO₂ surface through covalent bonding, forming positively charged sulfonic acid sites ([O_1.5Zr-O]^δ−-SO3H^δ+) with a loading of 3.6 mmol/g. As a result, SZO exhibited excellent removal efficiency (≥91.3%) and high breakthrough adsorption capacity (ranging from 38.59 to 82.07 mg/g) for o-xylene in the temperature range of 130 –150 °C. In contrast, sulfonic acid groups are anchored on the MgO surface via ion-paired bonding, leading to the formation of negatively charged sulfonic acid sites ([O_0.5Mg]⁺:OSO₃H⁻), which prevents their participation in the electrophilic sulfonation reaction with o-xylene molecules. This work provides new insights into tuning and enhancing the performance of supported sulfonic acid materials for the resource-oriented treatment of aromatic VOCs.

Antibiotic resistance has been recognized as a global threat to human health. Therefore, it is urgent to develop effective strategies to address the contamination of water environments caused by antibiotics. In this study, Fe/Mn bimetallic-modified biochar (FMBC) was synthesized through a one-pot oxidation/reduction-hydrothermal co-precipitation method, demonstrating an exceptional photocatalytic-Fenton degradation performance for oxytetracycline (OTC). Characterization techniques including FTIR, SEM, XRD, VSM, and N₂ adsorption–desorption analysis confirmed that the Fe/Mn bimetals were successfully loaded onto the surface of biochar in the form of Fe₃O₄ and MnFe₂O₄ mixed crystals and exhibited favorable paramagnetic properties that facilitate magnetic recovery. A key innovation is the utilization of biochar’s inherent phenol/quinone structures as reactive sites and electron transfer mediators, which synergistically interact with the loaded bimetallic oxides to significantly enhance the generation of highly reactive ·OH radicals, thereby boosting catalytic activity. Even after five recycling cycles, the material exhibited minimal changes in degradation efficiency and bimetallic crystal structure, indicating its notable stability and reusability. The photocatalytic degradation experiment conducted in a Fenton-like reaction system demonstrates that, under the conditions of pH 4.0, a H₂O₂ concentration of 5.16 mmol/L, a catalyst dosage of 0.20 g/L, and an OTC concentration of 100 mg/L, the optimal degradation efficiency of 98.3% can be achieved. Additionally, the pseudo-first-order kinetic rate constant was determined to be 4.88 min⁻¹. Furthermore, this study elucidated the detailed degradation mechanisms, pathways, and the influence of various ions, providing valuable theoretical insights and technical support for the degradation of antibiotics in real wastewater.

A group of silica-based supports with varying Al/Si ratios (S−x) was synthesized using the sol–gel method, followed by a chlorosulfonic acid modification to produce supported sulfonic acids (SA−x). The S−x and SA−x materials, along with their adsorption products, were characterized via techniques such as FTIR, BET, and HPLC-MS. The analysis revealed that the sulfonic acid groups in the SA−x materials existed in two anchoring states: the covalently bonded (CB) state [SiOx–O]^ɗ−–SO₃H^ɗ+ and the ion-paired (IP) state AlO_y⁺:OSO₃H⁻. The sulfonation reactivity of the CB-state sulfonic acid was enhanced, whereas that of the IP-state counterpart was diminished. The incorporation of a minor quantity of aluminum ions (x = 0.1) markedly enhanced the adsorption efficiency of SAs for o-xylene, extending the reaction temperature range to 110–190 °C and increasing the breakthrough adsorption capacity (Q_B) to 946.1 mg g⁻¹. However, excessive aluminum ion incorporation was detrimental to the adsorption performance of SAs for o-xylene. SA−0.1 showed superior adsorptive capabilities and excellent recyclability, maintaining its performance over four consecutive adsorption/regeneration cycles with only a minor decrease of 4.5%. These findings suggest that SAs prepared with a minor amount of aluminum ions have significant potential for application as adsorbents for the removal of benzene series pollutants.