Clean Utilization Research Articles

Proposal and performance analysis of a novel hydrogen and power cogeneration system with CO2 capture based on coal supercritical water gasification

To establish a sustainable energy system, it is essential to achieve low-carbon and clean utilization of coal. In this study, a novel hydrogen and power cogeneration system with full CO2 capture that based on coal supercritical water gasification (SCWG) is proposed. Hydrogen is separated from syngas produced by coal SCWG, and the remaining combustible gas is burned to generate power. Moreover, supercritical CO2 cycle is integrated within the cogeneration system to recover the waste heat with high exergy efficiency. Thermodynamic performances, effects of key operation parameters and off-design performances under part-load conditions of the cogeneration system are analyzed. Under the design condition, the cogeneration system produces 20.26 mol kg−1 hydrogen and generates 8746 kJ kg−1 net power, achieving the high energy efficiency and exergy efficiency of 54.77 % and 52.54 %. The exergy efficiency of cogeneration system can be enhanced by optimizing the operation parameters, which is increased by 0.42 %, 4.03 % and 1.10 % with the optimal coal water slurry concentration (17.5 %), higher gasification temperature (750 °C) and higher gas turbine inlet parameters (1500 °C/3 MPa), respectively. The cogeneration system performance decreases with the power load, and the exergy efficiency decreases by 9.61 % when the system power load reduces from 100 % to 30 %.

On the lower explosion limit of ventilation air methane under high temperatures

Regenerative thermal oxidation of Ventilation-Air-Methane is a technology for clean utilization of energy. Increasing methane concentration can enhance utilization efficiency, but pose a risk of explosion. To ensure the safe and effective utilization of VAM, critical concentration of oxidation to explosion is determined through experiments and simulations. Results indicate that GRTO model established by our group exhibits the highest prediction accuracy of 99.57%. The model was selected to study critical mechanisms of oxidation to explosion, thereby providing theoretical guidance for VAM utilization. The oxidation process can be divided into three stages: CH4 pyrolysis, rapidly generation/consumption of ·CH3/·HCO, and CO oxidation. With temperature rises from 600 °C to 800 °C and then to 1000 °C, the explosion limit of methane decreases mainly by speeding up ·H + O2⇔·O+·OH, and the ignition timing at critical limit shifts from the stage of ·CH3O generation/consumption to ·CH3 generation/consumption, and ultimately to ·OH formation/accumulation.

From hydratable alumina bonded high chrome castables to shaped product for coal water slurry gasifier

The gasifier is a key equipment of coal gasification technology, enabling efficient and clean utilization of coal resources. However, the aluminum phosphate bonded high chrome brick lining in the gasifier experienced premature failure due to the migration of phosphate in reducing gases such as H2 and CO, as well as increased slag penetration and thermal spalling. In this study, a high chrome castable was prepared using hydratable alumina as a binder and fired at 1600 ℃ to replace the traditional phosphate bonded high chrome brick. The impact of curing temperatures (25℃, 40 ℃, and 60 ℃) on the properties of the high chrome castable was investigated, with corresponding hydrates examined through XRD, FTIR, TG-DSC, and SEM analyses. Results revealed that higher curing temperatures accelerated the hydration process of hydratable alumina. At higher curing temperatures, more well-developed micro-nano sized boehmite and bayerite phases were formed within the castables, filling their pores effectively and enhancing their properties after drying at 110 ℃. Moreover, during heat treatment these micro-nano sized hydrates decomposed into submicron/nano sized alumina which readily reacted with Cr2O3 to form (Cr-Al)2O3 solid solution. This phenomenon facilitated the sintering of castables fired at 1600 ℃ and optimized internal structure, ultimately leading to the enhanced mechanical properties and improved slag resistance.

Regulation of co-pyrolysis behavior of Naomaohu coal and polypropylene by controlling the cracking of polypropylene pyrolysis volatiles

Pyrolysis is one of the technologies for clean and efficient conversion and utilization of coal, however, low yield and poor quality of tar restrict its utilization. Waste polypropylene (PP) could be efficiently used to improve tar yield of low-rank coal via co-pyrolysis. To strengthen the generation and transfer of hydrogen-rich radicals, modified HZMS-5 (HZ5) catalyst was used to regulate the composition of PP pyrolysis volatiles. Results show that close contact between HZ5 catalyst and coal favors the formation of light components, which reaches the maximum value of 72.45 wt%. In the presence of zeolite catalysts modified with 0.2 mol/L NaOH (0.2Na-HZ5), light oil in tar exhibits an obvious increase of 12.78 % compared with HZ5. A synergetic effect analysis clarifies that C2-C3 produced from PP pyrolysis under the action of the catalyst participate in the formation of tar. And the reactive intermediates from secondary cracking of PP volatiles over 0.2Na-HZ5 promote the cleavage of O-containing groups in coal, leading to the increase of phenols and alcohols in tar. The co-pyrolysis behavior of benzyl phenyl ether /bibenzyl and PP is shown that the transfer of oxygenated compounds into liquid is enhanced, confirming a positive synergetic effect. Meanwhile, the clear inhibition of C2-C3 components further indicates their contribution to tar formation.

Research on the Economic Environmental Impact and Carbon Reduction Pathways of Power Battery Industry Development - A Case Study of Yibin City

Abstract The power battery industry in China is experiencing rapid development, with the swift expansion of capacity potentially posing challenges to environmental protection and carbon reduction. Using the development plan of the power battery industry in Yibin City as a case study, this paper employs the Material Flow Analysis and Tapio decoupling model to deeply explore the economic benefits and environmental burdens brought by the development of power battery key industry under scenarios, proposing optimized pathways to promote low-carbon industrial development. The results indicate that the industrial output value can increase from 92.1 billion CNY in the baseline year to 382.6 billion CNY in 2030, with carbon emissions rising from 0.55 million tons to 2.32 million tons. The adjustment of product structure has limited effect on carbon reduction in the power battery industry. In the short term, optimizing the energy structure has greater carbon reduction potential than improving energy efficiency, and clean energy utilization has the highest marginal carbon reduction effect. Implementing measures to optimize the energy structure and improve efficiency simultaneously can achieve weak decoupling of economic growth and carbon emissions, though strong decoupling is challenging to attain. The proportion of local renewable energy generation also impacts the low-carbon capability of the industry, suggesting that regions with abundant renewable energy should be prioritized for industrial layout. Promoting the decoupling of economic growth and environmental impact in the power battery industry can be facilitated by supporting environmental governance infrastructure, driving the green energy transition, and encouraging low-carbon technological innovation. JEL classification numbers: F062.2 Keywords: Power battery, Scenario analysis, Material flow, Economic environmental impact, Carbon emissions.

Computational fluid dynamics simulation on oxy-fuel combustion performance of a multiple-burner furnace firing coking dry gas

In heat production and power generation utilizing carbon-based fuels, oxy-fuel combustion is regarded as a potential method for carbon capture and sequestration. However, few studies, if any, have been performed on the impacts of exhaust dehydration efficiency and oxygen purity on the parameters of oxy-fuel combustion. In the current study, based on the experimental data, the oxy-fuel combustion characteristics of coking dry gas (CDG) in a gas-fired furnace were investigated using the computational fluid dynamics approach. The simulation results illustrate that the CO2 concentration in the flue gas could rise by nearly 14% as the dehydration efficiency increases from 0.60 to 0.95. The contents of CO2 elevate with the oxygen purity, while H2O and N2 show an opposite trend. Within the scope of the present study, an O2 content of 32% and an excess oxygen ratio of 1.1 are recommended given the combustion performance and economic issue. Due to the impacts of combustion performance, cost of ASU, CO2 enrichment, and so on, the selection of oxygen purity needs to be considered comprehensively. The content of N2 declines with the increase of the dehydration efficiency, which benefits the enrichment of CO2. The present work contributes to the clean and efficient utilization of combustible exhaust gas and provides further knowledge on green and low-carbon development.

Enhanced energy efficiency and fast co-pyrolysis characteristics of biogas residues and long-flame coal using infrared heating and TG-FTIR-MS

Co-pyrolysis may enhance the energy efficiency of anaerobic digestion waste (biogas residues), while simultaneously facilitating the clean utilization of coal. A thermogravimetric analyzer (TG), TG-FTIR-MS, and infrared heating technique were employed to investigate the rapid co-pyrolysis properties of long-flame coal (LFC) and biogas residues (BR) in this study. Meanwhile, the effects of temperature on the co-pyrolysis product distributions and compositions were studied in reactors that were heated with electric heating and rapid infrared heating. The co-pyrolysis of LFC and BR had the potential to decrease greenhouse gas emissions, as indicated by the TG-FTIR/MS findings. The co-pyrolysis kinetics were calculated using two models (KAS and FWO); the average Eα values are 176.09 and 187.26 kJ/mol, respectively. Tar yields increased initially in IH (electric heating) and EH (infrared heating) reactors, before declining as the temperature rose. The tar yields are greatest for EH at 500 °C (16.12 wt%) and IH at 600 °C (16.02 wt%). Tar yields generated via infrared heating were greatly higher than those generated by EH at 600–700 ℃. IH has a higher tar yield due to the fact that there are significant synergistic effects between coal and lignin, protein, and lipid at high temperatures. The GC-MS results indicate that IH has promoted the aromatization and ketonization reactions. Moreover, more monocyclic aromatic and bicyclic aromatic products are generated by infrared heating, suggesting an indication of tar quality improvement. An elevated co-pyrolysis temperature results in a greater degree of graphitization in char.

Exploring the molecular characteristics of organic matter in low-rank coals using GC×GC/TOF-MS plus data mining

In-depth understanding the form of organic matter in low-rank coals contributes to the clean and efficient utilization of coals. Two low-rank coals were successively dissolved with cyclohexane, acetone and methanol at 300 °C, respectively. Six thermal dissolution (TD) extracts were comparatively analyzed using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC/TOF-MS). Cyclohexane tends to extract low-polar compounds inherent in coal, such as aliphatic hydrocarbons, arenes and phenols. Acetone can extract monocyclic aromatic hydrocarbons containing alkyl side chains. Meanwhile, acetone can form N-H⋯O hydrogen bonds with nitrogen-containing organic compounds (NCOCs), facilitating the extraction of a greater quantity of NCOCs. Methanol breaks the ArCH2OArR structural unit within coal molecules and forms the dominant alkyl-substituted phenol. It was revealed that sequentially TD at 300 °C using different solvents only breaks intermolecular forces and weak covalent bonds. Additionally, a series of isomers of tricyclic aromatic hydrocarbons and alkylphenols were authenticated by GC×GC/TOF-MS. Principal component analysis and hierarchical clustering analysis were applied to mine effective molecular information from the extensive MS data. The statistical results indicate that solvent had a significant impact on the structure and composition of the TD extracts, more so than the variations in coal species. Thus, the conjunction of GC×GC/TOF-MS and chemometrics provided methodological guidance for an enhanced comprehension of the molecular structure of coals.

Facile preparation of heat-conducting ceramics/epoxy composites by pre-constructing Si3N4–SiC skeleton from photovoltaic silicon waste

As a by-product of solar panel production, photovoltaic silicon waste (PSW) is becoming a threat to the environment and human health. The classical resource recycling approaches are separating Si and SiC from PSW, most of which is costly and inefficient. In this study, the PSW acted as a silicon source was directly translated into a vertically oriented 3D Si3N4–SiC skeleton with ice-templating and in situ nitriding technology. The Si3N4–SiC/epoxy (EP) composites were successfully produced by the following vacuum epoxy infusion. Composite with 55.46 wt% filler content had the maximum thermal conductivity (TC) of 1.717 W/(m·K), 950 % higher than pure epoxy. The composite substrates showed excellent heat dissipation performance in practical applications due to their high TC, primarily attributed to the directional arrangement of ceramic powders in the Si3N4–SiC skeleton. Additionally, the Si3N4 whiskers produced in situ promoted the formation of wider continuous phonon heat transfer channels. In short, we proposed a simple and feasible approach for recycling PSW to fabricate high-value heat-conducting composites, which expands a new direction of industrial waste secondary recycling and is of great importance for the clean utilization of the resource.

Effect of toluene on siloxane biodegradation and microbial communities in biofilters

The removal of volatile methyl siloxanes (VMS) from landfill biogas is crucial for clean energy utilization. VMS are usually found together with aromatic compounds in landfill biogas of which toluene is the major representative. In the present study, two biofilters (BFs) packed with either woodchips and compost (WC) or perlite (PER) were used to study the (co–) removal of octamethyltrisiloxane (L3) and octamethylcyclotetrasiloxane (D4) from gas in presence and absence of toluene, used as a representative aromatic compound. The presence of low inlet toluene concentrations (315 ± 19 – 635 ± 80 mg toluene m-3) enhanced the VMS elimination capacity (EC) in both BFs by a factor of 1.8 to 12.6. The highest removal efficiencies for D4 (57.1 ± 1.1 %; EC = 0.12 ± 0.01 gD4 m-3 h-1) and L3 (52.0 ± 0.6 %; EC = 0.23 ± 0.01 gL3 m-3 h-1) were observed in the BF packed with WC. The first section of the BFs (EBRT = 9 min), where toluene was (almost) completely removed, accounted for the majority (87.7 ± 0.6 %) of the total VMS removal. Microbial analysis revealed the impact of VMS and toluene in the activated sludge, showing a clear selection for certain genera in samples influenced by VMS in the presence (X2) or absence (X1) of toluene, such as Pseudomonas (X1 = 0.91 and X2 = 12.0 %), Sphingobium (X1 = 0.09 and X2 = 4.04 %), Rhodococcus (X1 = 0.42 and X2 = 3.91 %), and Bacillus (X1 = 7.15 and X2 = 3.84 %). The significant maximum EC values obtained by the BFs (0.58 gVMS m-3 h-1) hold notable significance in a combined system framework as they could enhance the longevity of traditional physicochemical methods to remove VMS like activated carbon in diverse environmental scenarios.

A new strategy for clean utilization of zinc oxide dust: Preparation of spinel zinc ferrite by solid phase reaction and its catalytic degradation of organic wastewater

The resource utilization of zinc oxide dust (ZOD) is mainly focused on the efficient recovery of zinc by acid leaching at present. Because of a large amount of iron in ZOD and zinc components existing in multi-phase, the problems of low zinc recovery and the separation of zinc and iron ions in the leaching solution are unavoidable. Considering the characteristics of ZOD and the advantages of spinel zinc ferrite (ZnFe2O4) in the advanced oxidation degradation of organic wastewater, a new strategy for clean utilization of ZOD is proposed. The leaching efficiency of soluble zinc components in ZOD reached 96.7 % by selective dissolution with low concentration sulfuric acid solution, and the leaching solution without iron ions can be directly used for electrolytic zinc recovery. The insoluble components of zinc and iron in the leaching residue were converted into ZnFe2O4 by solid phase roasting. By adjusting the roasting temperature, time and molar ratio of Fe/Zn in roasting process, the proportion of zinc elements in the form of ZnFe2O4 reached 99.56 % and a single spinel zinc ferrite product was obtained. Zinc ferrite product activated by ball milling for 2 h (ZFO-2) showed very high catalytic activity in the treatment of organic wastewater by peroxonosulfate (PMS). In the presence of 1 mM PMS and 1 g/L ZFO-2 at 20 °C, the ZFO-2/PMS system achieved a removal rate of over 90 % within 40 min for wastewater containing RhB, MO and MG (10 mg/L). In addition, ZFO-2 is ferromagnetic and easily recovered by magnetic separation. The new strategy proposed in this paper takes into account the efficient recovery of soluble zinc components and the cooperative high-value utilization of insoluble components of zinc and iron in ZOD, which is a comprehensive utilization method with more sustainable resource allocation.

Identification of the Key Issues and Technical Paths for Intelligent Operation of Water Source Heat Pump Energy Stations Applying Digital Twin Technology

To address the challenges posed by global climate change, developing green energy systems characterized by informatization, digitalization, and intelligence is crucial for achieving carbon neutrality. This article is a research report type paper on water source heat pump (WSHP) energy stations, aiming to use digital twin technology and other information technologies to resolve conflicts between clean energy development and efficient energy utilization. The primary objective of this study is to identify and analyze issues in traditional energy station operations and management systems. Based on this analysis, specific technical solutions are proposed, including pathways for technological research, methodologies, and content. The results provide a comprehensive theoretical framework for the intelligent transformation of energy station systems and essential technical support for the WSHP energy station project in the Hankou Binjiang International Business District. The findings have significant implications for the widespread adoption of WSHP energy stations and the achievement of national carbon neutrality goals.

A clean and green technology for iron extraction from refractory siderite ore via fluidization self-magnetization roasting

As a refractory iron resource, siderite has gained significant attention in the fields of mineral processing and metallurgical industry due to its abundant availability. However, its direct utilization in iron and steel production is often hindered by the presence of impurities, including silicates and carbonates, as well as the lower theoretical iron grade so it is necessary to increase iron and reduce impurities. To unlock the full potential of these abundant iron ore deposits, advanced processing techniques are imperative. In this work, a clean and green technology was proposed for extracting iron from siderite via fluidization self-magnetization roasting and magnetic separation. The mechanism of fluidization self-magnetization was investigated by thermodynamic analysis, X-ray diffraction (XRD), iron phase analysis, Mineral Liberation Analyzer (MLA), vibrating sample magnetometer (VSM), scanning electron microscope (SEM) combined with energy dispersive spectroscopy (EDS). The results show that concentrate with a Fe grade of 61.74% and Fe recovery of 81.78% could be obtained after treatment by fluidization self-magnetization roasting and magnetic separation. The analysis reveals the siderite eventually transformed into magnetite after fluidization self-magnetization roasting, with the saturation magnetization increasing from 0.91 A·m2·kg−1 to 7.92 A·m2·kg−1. In this process, many cracks were generated on the surface of the ore, which not only likely contributes to the self-magnetization roasting but also facilitates the individual dissociation of iron minerals from gangue minerals during the grinding process. Subsequently, iron minerals can be recovered through magnetic separation. The fluidization self-magnetization roasting technology demonstrates significant potential in achieving the green and clean utilization of siderite.

Insights into pyrolysis product characteristics and carbon structure evolution of bituminous coal under high-temperature thermal shock

The current investigation aims to reveal the pyrolysis characteristics and particle microstructure evolution of bituminous coal under the high-temperature thermal shock. In the experimental temperatures, the purification of carbon matrix in the coal char is a successive process linear on temperature. In contrast, the graphitization process of carbon structure existed a transition temperature (1600 ℃). Specifically, the range of 1000–1500 ℃ is critical for the transformation of amorphous carbon to disordered graphite, but the growth of graphite microcrystals was minimally affected. While the range of 1600–1900 ℃ is critical for the formation of the graphite-like carbon structure. It is characterized by the release of defective structures such as oxygen-containing functional groups, and a significant increase in crystal size. Although beneficial for the subsequent study of carbon materials, the ordered graphite transformation led to the deactivation of char. The pyrolysis behavior study under thermal shock insight into the thermal behavior of coal char in high-temperature furnaces, as well as a new idea for the clean utilization of coal resources.

Numerical investigation on the energy extraction characteristics of parallel multi foils arranged in columns

Abstract The oscillating foil is a focus device in the clean energy utilization field. The presence of an oscillating foil structure within the flow field significantly impacts the energy extraction capabilities of the system. In this paper, three types of parallel multi-foil structures arranged in columns are proposed. The energy extraction characteristics of diverse multi-foil structures under various oscillation conditions are analyzed numerically. The flow field structure and the impact of parallel multi foils on the aerodynamic characteristics are investigated. Results demonstrate that the multi-foil structure with a phase difference of 180° achieves the highest level of energy extraction performance, and the maximal mean power coefficient achieves 0.894, which is 11.03% higher than that of the structure with a smaller phase difference. The size of the trailing edge vortex under the structure with a phase difference of 180° is significantly larger, leading to an obvious fluctuation in the aerodynamic lift.

Deep removal of arsenic from arsenic-bearing gypsum using a seed-induced crystal control technique and its mechanisms

Arsenic-bearing gypsum (ABG), a byproduct from the lime/ferric sulfate process in the waste acid treatment of the heavy non-ferrous industry, represents a substantial hazardous arsenic (As) waste issue in China. Due to the potential arsenic leakage, the disposal of ABG poses an urgent challenge to the surrounding environment. The elevated As content and the low-value-added recycling products are the primary hurdles hindering ABG recycling. In this study, precise control over the gypsum crystal and As species in Na2SO4-H2SO4 solutions under mild conditions facilitated the deep removal of As (with a leaching efficiency of 92.45 % and a final product As concentration of 80.32 ppm) and simultaneous preparation of high-strength α-bassanite (with a compressive strength of 35.38 MPa) from the pre-treated ABG. This process occurred during the recrystallization from dihydrate gypsum (CaSO4·2H2O, DH) to α-bassanite (α-CaSO4·0.5H2O, α-HH), involving DH dissolution followed by α-HH crystallization. The encapsulated As was fully released during the dissolution process, crucial for the efficient elimination of As impurities. H2SO4 dissolved the released As, transforming it into the protonated species (H3AsO4) with a distinct structure and a less negative binding energy (ΔEB) to SO42-. This transformation prevented the chemical incorporation of the released As during the α-HH crystallization process. Additionally, the morphology and size of α-HH were controlled by seeding in the mixed solutions. The formation of large short-columnar α-HH crystals with a low specific surface area significantly reduced the surface adsorption of As, further enhancing As leaching efficiency. Importantly, the large short-columnar α-HH was identified as high-strength gypsum with high added value. This study provided innovative guidance for efficiently removing impurities from gypsum and pioneered a cost-effective approach for the clean and high-value utilization of industrial gypsum residues.

Coal-based carbon nanosheets contained carbon microfibers modified with grown carbon nanotubes as efficient air electrode material for rechargeable zinc-air batteries

Coal-based oxygen electrocatalysts hold immense promise for cost-effective applications in rechargeable Zn-air batteries (ZABs) and the value-added, clean utilization of traditional coal resources. Herein, an electrospun membrane electrode comprising coal-derived carbon nanosheets and directly grown carbon nanotubes (CNS/CMF@CNT) was successfully synthesized. The hierarchical porous structure of the electrode, composed of multiple components, significantly facilitates mass and ion transportation, resulting in exceptional electrochemical performance. Employing Fe as the catalyst for CNT growth, the CNS/CMF@CNT electrode exhibits a remarkable onset potential of 0.96 V and a half-wave potential of 0.87 V in the oxygen reduction reaction (ORR). In-situ surface-enhanced Raman spectroscopy reveals that hydroxyl radical desorption on the surface of CNS/CMF@CNT(Fe) is the rate-determining step of the ORR. Notably, the aqueous ZAB featuring the CNS/CMF@CNT(Fe) electrode achieved a peak power density of 216.0 mW cm−2 at a current density of 414 mA cm−2 and maintained a voltage efficiency of 65.1 % after 2000 charge/discharge cycles at 5 mA cm−2. Furthermore, the all-solid-state ZAB incorporating this electrode displayed an open-circuit voltage of 1.43 V, a peak power density of 70.1 mW cm−2 at a current density of 110 mA cm−2, and a voltage efficiency of 66.5 % after 150 charge/discharge cycles. The utilization of abundant coal as the raw material for electrode fabrication not only brings conceivable economic benefits in ZAB construction, but also commendably advances the effective application of traditional coal resources in a more sustainable manner.

Synthesis and structure–property relationship of coal-based isomeric alkylbenzene sulfonate surfactants

Using coal resources to synthesize high-value surfactants is effective for clean coal utilization and low-carbon conversion, attracting more attention from academia and industry. Herein, three coal-based isomeric alkylbenzene sulfonate surfactants were successfully synthesized via sulfonation with gas phase SO3 utilizing isomeric alkylbenzenes, derived from the alkylation of benzene and Fischer–Tropsch synthesized α-olefins, as raw materials in a microchannel reactor. Moreover, their surfactant properties were systematically investigated to reveal the structure–property relationship. The results indicated that the equilibrium surface tension (γCMC) for the synthesized surfactants was reduced with the increase of the degree of hydrophobic tails branching, and the order of γCMC was: sodium dodecylbenzene sulfonate (35.67 mN·m−1) > sodium C6 olefin dimer alkylbenzene sulfonate (34.18 mN·m−1) > sodium dihexylalkylbenzene sulfonate (29.94 mN·m−1). Sodium dihexylalkylbenzene sulfonate with the lower γCMC exhibited superior wettability (the contact angle of 50.2 ° at 30 s) and excellent emulsifying capacity (emulsification time of 1337 s) at the corresponding critical micelle concentration. This study provides new insights into rational design of hydrophobic tail architectures of surfactant molecules to meet specific needs in various fields.

Experimental study on the co-firing and NOx emission characteristics of bituminous coal and its medium temperature pyrolysis char

To address the issues of ignition difficulty, incomplete burnout, and high NOx emissions during coal char combustion in industrial applications, a series of co-firing experiments involving bituminous coal and its medium-temperature pyrolysis char were conducted using a micro fluidized bed analysis system. The experiments explored co-firing behaviors and NOx emission characteristics for five different fuel blending ratios in an environment with 21 % oxygen concentration, across temperatures between 923 K and 1223 K. The study delved into the synergistic effects of coal and char co-firing, as well as the influence of combustion temperature and fuel blend ratio on the co-firing efficiency and NOx emissions. The results show a synergistic effect in the co-firing of bituminous coal and char, influenced by reaction temperature and coal-to-char blend ratio, which evolves as combustion progresses. In the 923–1073 K range, initial coal addition to the blend enhances reactivity. However, as the reaction advances or coal content exceeds 75 %, this synergy shifts to an inhibitory effect. At temperatures above 1023 K, increased proportions of coal in the blend are associated with improved burnout rates, especially when the coal content is at or above 50 %. Moreover, at a combustion temperature of 1123K, there is a marked decrease in nitrogen oxide emissions, with coal blend ratio of 25 % and 50 % showing particular efficacy in reducing these emissions. These results provide valuable insights for the efficient and clean utilization of coal char in industrial combustion processes.

The friction pair composed of polymers and Bi12TiO20 facilitates the tribocatalytic degradation of organic pollutants

In recent years, friction-induced tribocatalysis has garnered significant attention in the fields of environmental pollution and clean energy utilization. Despite its efficacy in converting mechanical energy into chemical energy, the degradation process is time-consuming, which limits its practical applications. In this study, we optimized the morphology of Bi12TiO20 catalyst and employed the most active Bi12TiO20 combined with four kinds of triboelectric polymer powders to form an efficient friction pair that enhances the tribocatalytic efficiency for organic pollutant degradation. The amount of polymer added, stirring rate, number and shape of stirring bars, as well as the materials of stirring bars and beakers were investigated. The recycled tribocatalyst exhibited recyclability and stability in degrading organic pollutants. The hydroxyl and superoxide radicals were quantitatively determined, and the generation and mechanism of positive and negative charges in the process of tribocatalysis were analysed. The potential mechanisms underlying charge generation during tribocatalysis were investigated, while also exploring the degradation pathway of Rhodamine B through high-efficiency tribocatalysis.