Conversion Routes Research Articles

An emerging route for efficient conversion of monopotassium phosphate via a pilot-scale electrodialysis metathesis

This study explores energy-efficient KH₂PO₄ (KDP) preparation, examining its implications for sustainability, and offers insights on enhancement and benefits. For the first time, electrodialysis metathesis (EDM) process was considered as a potential technique for efficient conversion and cleaner production of KDP in this study. The effects of key operational parameters including applied voltage, initial feed concentration, concentration ratio, and volume ratio on the conversion performance of EDM were systematically investigated. The promising conditions were established with an applied voltage of 2.3 V per repeating unit, a concentration ratio of 0.5 M NH4Cl to 0.6 M KCl, and a critical 1.43-fold volume ratio, yielding a high-purity KDP solution of 96.65 % at 78.52 g/L with an energy consumption rate of 0.52 KWh/kg. An economic evaluation indicates a 15.4 % cost reduction compared to the market price, presenting the EDM process as a viable and leading technology for the production of high-purity KDP.

4E evaluation and multi-objective optimization of low concentration flue gas CO2 capture and multi-product conversion process

In order to address the current global warming, this work proposes CO2 capture from flue gas and CO2 hydrogenation to produce methane, methanol, and CO2 to produce ammonium bicarbonate. Aspen Plus process simulation model is developed for the three processes. Based on the thermodynamic model, sensitivity analysis of main operating parameters is conducted on the energy, economic, environment, and exergy (4E) indicator. Non-dominated sorting genetic algorithm is used to achieve multi-objective optimization. The optimum operating parameters of the three processes are obtained under the 4E indicators. It is concluded that the CO2 to ammonium bicarbonate is the optimal process route for CO2 conversion. The corresponding total annual cost is 4.071 M$/year, the CO2 equivalent emission per unit product is −0.0667 tCO2/t pro, the annual total utility consumption is 7062.75 kW/year, and the exergy efficiency of system is 53.42 %. This work shows significance for achieving resource utilization with capture CO2.

Optimization of C5+ production by CO2 recycle at an integrated Tri-reforming and Fischer-Tropsch process

Integration of Tri-reforming and Fischer-Tropsch processes is a novel approach for conversion of CO2 into C5+ liquid hydrocarbon. Tri-reforming converts CO2 into syngas and does not require external heat source due to methane oxidation reaction that occurs at the beginning of reactor. Fischer-Tropsch synthesis converts produced syngas in the reformer to hydrocarbon fuels. In this research, plug reactors have been modeled in a heterogeneous and one-dimensional form, and the mass and energy equations governing them in steady state have been developed. The accuracy of models is validated with literature data. Then an optimization problem aiming at maximal C5+ production is compiled with specific limitations imposed on operating conditions. Based on the modeling results, 95 % of CO2 produced at Fischer-Tropsch and 92 % CO2 produced at Tri-reforming process is captured and injected into Tri-reforming reactor for conversion into hydrocarbon fuels. Modeling results revealed that the mole fractions of C2-C4 and C5+ at outlet of Fischer-Tropsch are 0.117 and 0.023 which could be purified in separators and used as clean energy carriers. The suggested integrated route for CO2 capture and conversion into green fuels offers both environmental and technical advantages.

Mathematical Modeling of Biogas Production in Sanitary Landfills

Objective: The objective of this study is to evaluate the biogas production potential in sanitary landfills using the Verhulst mathematical model, which is employed to represent natural phenomena constrained by a saturation point. Theoretical Framework: It was based on references on energy use from waste, possible conversion routes, in addition to mathematical models that estimate the energy potential for biogas generation. Method: The methodology adopted for this research involves the use of data collected in an experimental cell, subsequently applying the De Verhulst model through a regression with minimization of errors using the Least Squares Method (LSM). Results and Discussion: The results indicated that the developed model correlates well with the observed data, demonstrating its suitability as a predictive model for biogas production. Research Implications: The research contributes to the construction of a theoretical framework for the adaptation, elaboration and use of mathematical models to predict the energy potential in the generation of biogas in landfills. Originality/Value: This study contributes to the literature by using a population growth model (Verhulst) to predict landfill biogas production.

Towards value-added chemicals: Technical and environmental life cycle assessment evaluation of different glycerol valorisation pathways

Biodiesel is acknowledged as the most appropriate biofuel to decarbonise the transport sector and combat climate change. The ever-increasing biodiesel production via transesterification results in large amount of glycerol (e.g., 10 kg of glycerol for every 100 kg of biodiesel). Converting glycerol into value-added goods is perceived to be a viable way to lower the high cost of producing biodiesel and expand its market share. The current study examines the technical and environmental aspects of bio-hydrogen, bio-syngas, acrolein, propylene glycol, epichlorohydrin, bio-methanol and bio-ethanol synthesis. CHEMCAD process simulation software was used to perform the modelling and simulation aspects considering a glycerol flowrate of 100 kg/h. The environmental study is based on primary and secondary data and is carried out using the Life Cycle Assessment methodology and the LCA for Experts software, using ReCiPe as the impact assessment method. The technical evaluation points towards glycerol conversion to propylene glycol and bio-methanol production as the best approaches given the relatively low energy requirements, increased purity (>97 wt%) and steadily growing product market. Bio-methanol exhibits the best environmental performance among all examined scenarios, providing the lowest impact in eight out of eleven categories studied while placing second in terms of FETP impact. Glycerol conversion towards propylene glycol seems as the second-best conversion route as it generates the lowest score in regards to GWP impact (0.31 kg CO2 eq./ kgproduct). Ultimately, the most effective methods for valorizing glycerol and improving the production of biodiesel by lowering the expenses related to its manufacturing are glycerol reforming toward bio-methanol and propylene glycol.

Unimolecular isomerizations of C6H6•+ radical cations: a computational study.

Eighteen concerted isomerization reactions of various C6H6•+ radical cation (RC) species are studied and found to proceed via well-defined transition states, whose relative positions along the reaction pathway generally agree with Hammond's postulate. From the barrier heights, the rate coefficients of these reactions are estimated by using transition state theory, and the activation energies are computed. Through combination among themselves, these 18 isomerizations yielded 15 multi-step conversion routes of various C6H6•+ species to the lowest energy benzene radical cation isomer 1, which routes are compared. Use is made of DFT with the B3LYP and M06-2X functionals, along with the CBS-QB3 approach to arrive at better energies. From the barrier heights for each of the concerted reactions, canonical transition state theory was applied to evaluate rate coefficients k over the temperature range 200-500K. The Arrhenius activation energies were computed using the plot of ln k vs. 1/T.

Redefining the Symphony of Light Aromatic Synthesis Beyond Fossil Fuels: A Journey Navigating through a Fe-Based/HZSM-5 Tandem Route for Syngas Conversion.

The escalating concerns about traditional reliance on fossil fuels and environmental issues associated with their exploitation have spurred efforts to explore eco-friendly alternative processes. Since then, in an era where the imperative for renewable practices is paramount, the aromatic synthesis industry has embarked on a journey to diversify its feedstock portfolio, offering a transformative pathway toward carbon neutrality stewardship. This Review delves into the dynamic landscape of aromatic synthesis, elucidating the pivotal role of renewable resources through syngas/CO2 utilization in reshaping the industry's net-zero carbon narrative. Through a meticulous examination of recent advancements, the current Review navigates the trajectory toward admissible aromatics production, highlighting the emergence of Fischer-Tropsch tandem catalysis as a game-changing approach. Scrutinizing the meliorated interplay of Fe-based catalysts and HZSM-5 molecular sieves would uncover the revolutionary potential of rationale design and optimization of integrated catalytic systems in driving the conversion of syngas/CO2 into aromatic hydrocarbons (especially BTX). In essence, the current Review would illuminate the path toward cutting-edge research through in-depth analysis of the transformative power of tandem catalysis and its capacity to propel carbon neutrality goals by unraveling the complexities of renewable aromatic synthesis and paving the way for a carbon-neutral and resilient tomorrow.

Investigate the utilization of novel natural photosensitizers for the performance of dye-sensitized solar cells (DSSCs)

Dye-sensitized solar cells (DSSCs) offer a promising route for sustainable energy conversion, with natural photosensitizers emerging as attractive alternatives to conventional synthetic dyes due to their abundant resources, cost-effectiveness, and eco-friendly materials. However, the efficiency of DSSC utilizing natural photosensitizer remains low. In this study, we investigate the utilization of novel natural photosensitizers extracted from gambier leaves, gambier branches, cinnamon, and petiole of tectona leaves, which contain flavonoids/tannins, chlorophyll, and anthocyanins, aiming to achieve high-performance DSSCs. Five different solvents—ethanol, isopropanol, distilled water, methanol, and Zamzam water—are explored to optimize the extraction process of the natural dyes. The doctor blade technique is employed to coat TiO2 nanomaterials onto ITO glass substrates. UV–Vis spectrophotometry and FTIR spectroscopy are used to characterize the optical properties and structural composition of the dyes, revealing that flavonoid/tannin groups are the primary compounds responsible for light harvesting. The DSSC performance is evaluated under a 30 W lamp, adjusted to light intensity of 10 mW/cm2. As a result, the DSSCs using gambier leaf extract as photosensitizer demonstrate the highest recorded efficiency of 4.71 %, with a Jsc of 2.95 mAcm−2 and a Voc of 0.64 V. These findings contribute to advancing DSSC technology by leveraging the potential of natural photosensitizers for sustainable energy conversion applications.

Performance of the ChatGPT large language model for decision support in community pharmacy.

The aim of this study was to assess the ChatGPT-4 (ChatGPT) large language model (LLM) on tasks relevant to community pharmacy. ChatGPT was assessed with community pharmacy-relevant test cases involving drug information retrieval, identifying labelling errors, prescription interpretation, decision-making under uncertainty and multidisciplinary consults. Drug information on rituximab, warfarin, and St. John's wort was queried. The decision-support scenarios consisted of a subject with swollen eyelids and a maculopapular rash in a subject on lisinopril and ferrous sulfate. The multidisciplinary scenarios required the integration of medication management with recommendations for healthy eating and physical activity/exercise. The responses from ChatGPT for rituximab, warfarin, and St. John's wort were satisfactory and cited drug databases and drug-specific monographs. ChatGPT identified labeling errors related to incorrect medication strength, form, route of administration, unit conversion, and directions. For the patient with inflamed eyelids, the course of action developed by ChatGPT was comparable to the pharmacist's approach. For the patient with the maculopapular rash, both the pharmacist and ChatGPT placed a drug reaction to either lisinopril or ferrous sulfate at the top of the differential. ChatGPT provided customized vaccination requirements for travel to Brazil, guidance on management of drug allergies and recovery from a knee injury. ChatGPT provided satisfactory medication management and wellness information for a diabetic on metformin and semaglutide. LLMs have the potential to become a powerful tool in community pharmacy. However, rigorous validation studies across diverse pharmacist queries, drug classes and populations, and engineering to secure patient privacy will be needed to enhance LLM utility.

Supplying the ethanol demand for 2030 in Brazil as a land-based climate change mitigation alternative: Implications on greenhouse gases emissions

Transitioning from a fossil-based to a bio-based economy is crucial to climate action and achieving neutrality in greenhouse gas (GHG) emissions. Biofuel production is an essential land-based GHG mitigation alternative. However, it raises concerns about biodiversity conservation, competition with food production, and net GHG emissions associated with direct land-use change (dLUC). This study aims to assess how the location and conversion routes influence GHG emissions for sugarcane expansion in Brazil to supply ethanol demand projections for 2030. A consistent and significant reduction in GHG emissions is achievable by implementing a strategy that prioritizes the spatial distribution for ethanol biorefinery expansions based on georeferenced life cycle emissions, including dLUC emissions associated with sugarcane production. Because of conservative zoning for sugarcane expansion, dLUC emissions are not an overriding factor, representing less than 9.1 % of the total GHG mitigation potential. Despite that, accounting for georeferenced dLUC emissions when prioritizing expansion facilities leads to spatial differences. Regarding conversion routes and land requirements, using cellulosic biorefineries could meet future projected demand based on sugarcane production from 3.1 million hectares, mostly in currently degraded pastureland. Conventional refineries would require 5.5 million hectares to meet the same demand of 71 billion liters. Despite the 77 % higher land demand to produce the same volume of ethanol, conventional refineries with straw recovery could be considered if electricity generation is a priority. This study illustrates how Brazil can achieve GHG mitigation targets while attending to future energy demand and protecting areas with high biodiversity.

The Impact of Biomass Composition Variability on the Char Features and Yields Resulted through Thermochemical Processes.

This paper explores the intricate relations between biomass polymeric composition, thermochemical conversion routes, char yields and features in order to advance the knowledge on biomass conversion processes and customize them to meet specific requirements. An exhaustive characterization has been performed for three types of biomasses: (i) spruce bark, a woody primary and secondary residue from forestry and wood processing; (ii) wheat straws-agricultural waste harvest from arable and permanent cropland; and (iii) vine shoots, a woody biomass resulting from vineyard waste. Chemical (proximate and ultimate analysis), biochemical, trace elements, and thermal analyses were performed. Also, Fourier transform infrared spectroscopy, Scanning Electron Microscopy, and thermogravimetric analysis were conducted to establish the compositional and structural characteristics of feedstock. The main polymeric components influence the amount and quality of char. The high hemicellulose content recommends wheat straws as a good candidate especially for hydrothermal carbonization. Cellulose is a primary contributor to char formation during pyrolysis, suggesting that vine shoots may yield higher-quality char compared to that converted from wheat straws. It was shown that the char yield can be predicted and is strongly dependent on the polymeric composition. While in the case of spruce bark and wheat straws, lignin has a major contribution in the char formation, cellulose and secondary lignin are main contributors for vine shoots char.

Atmospheric reactive nitrogen conversion kicks off the co-directional and contra-directional effects on PM2.5-O3 pollution

As the two important ambient air pollutants, particulate matter (PM2.5) and ozone (O3) can both originate from gas nitrogen oxides. In this study, applied by theoretical analysis and machine learning method, we examined the effects of atmospheric reactive nitrogen on PM2.5-O3 pollution, in which nitric oxide (NO), nitrogen dioxide (NO2), gaseous nitric acid (HNO3) and particle nitrate (pNO3−) conversion process has the co-directional and contra-directional effects on PM2.5-O3 pollution. Of which, HNO3 and SO2 are the co-directional driving factors resulting in PM2.5 and O3 growing or decreasing simultaneously; while NO, NO2, and temperature represent the contra-directional factors, which can promote the growth of one pollutant and reduce another one. Our findings suggest that designing the suitable co-controlling strategies for PM2.5-O3 sustainable reduction should target at driving factors by considering the contra-directional and co-directional effects under suitable sensitivity regions. For co-directional driving factors, the design of suitable mitigation strategies will jointly achieve effective reduction in PM2.5 and O3; while for contra-directional driving factors, it should be more patient, otherwise, it is possible to reduce one item but increase another one at the same time.

Insights into hydro thermal gasification process of microplastic polyethylene via reactive molecular dynamics simulations

Microplastics have become a pressing environmental issue due to their widespread presence in our ecosystems. Among various plastic components, polyethylene (PE) is a prevalent and persistent contaminant. Hydrothermal gasification (HTG), a promising technology for converting PE into syngas, holds great promise for mitigating the microplastic problem. In this study, we employ ReaxFF molecular dynamics simulations to investigate the HTG process of PE, shedding light on the intricate relationships between temperature, water content, carbon conversion efficiency, and product distributions. The results reveal that hydrothermal gasification of PE is a complex process involving multiple reaction pathways. Consistently with experimental findings, the calculations indicate that the gas phase exhibits a substantial hydrogen fraction, reaching up to 70%. Interestingly, our simulations reveal a dual role of water content in the HTG process. On one hand, water enhances hydrogen production by promoting the gas formation. On the other hand, it elevates the activation energy required for PE decomposition. Depending on the water content, the calculated activation energies range from 176 to 268 kJ/mol, which are significantly lower than those reported for thermal gasification (TG). This suggests that HTG may be a more efficient route for PE conversion. Furthermore, this study highlights the importance of optimizing both temperature and water content in HTG systems to achieve high yields of hydrogen-rich syngas. The results obtained from our ReaxFF MD simulations demonstrate the robustness of this computational methodology in elucidating complex chemical reactions under extreme conditions. Our findings offer critical insights into the design of advanced waste management strategies for microplastics and contribute to the development of sustainable practices for resource recovery. This work underscores the potential of HTG as a key technology for addressing the global challenge of plastic pollution.

Efficient PAHs removal and CO2 fixation by marine microalgae in wastewater using an airlift photobioreactor for biofuel production

Microalgae cultures have emerged as a promising strategy in diverse areas, ranging from wastewater treatment to biofuel production, thus contributing to the search for carbon neutrality. These photosynthetic organisms can utilize the resources present in wastewater and fix atmospheric CO2 to produce biomass with high energy potential. In this study, the removal efficiency of Polycyclic Aromatic Hydrocarbons (PAHs), CO2 fixation and lipid content in the biomass produced from microalgae grown in airlift photobioreactor were evaluated. Four mesoscale cultures were carried out: Control (Seawater + Conway medium), Treatment A (Oil Produced Water + Poultry Effluent Water), Treatment B (Poultry Effluent Water + Seawater) and Treatment C (Oil Produced Water, Seawater and nutrients). The impact of biostimulation, through the addition of nutrients, on PAHs removal efficiency (up to 90%), CO2 fixation rate (up to 0.20 g L−1 d−1) and the composition of the generated biomass was observed. Primarily, the addition of nitrates to the culture medium impacted CO2 fixation rate of the microalgae. In addition, a direct correlation was observed between PAHs removal and lipid accumulation in the biomass, up to 36% in dry weight, demonstrating microalgae's ability to take advantage of the organic carbon (PAHs) present in the culture medium to generate lipid-rich biomass. The concentration of polysaccharides in the biomass obtained did not exceed 12% on a dry weight basis, and the Higher Heating Value (HHV) ranged between 17 and 21 MJ kg−1. Finally, the potential of generating hydrogen through pyrolysis was highlighted, taking advantage of the characteristics of biomass as a conversion route to produce biofuels. These results show that microalgae are effective in wastewater treatment and have great potential in producing biofuels, thus contributing to the transition towards more sustainable energy sources and climate change mitigation.

Light-driven acetic acid coupling for the production of succinic acid

Treating and recycling high concentration acetic acid in the exhaust water has long posed a challenge in industry. These wastes containing acetic acid are typically processed via basic neutralization, characterized by high acidity and resistance to degradation, which can bring potential economic burden and environmental hazards. Here we report a new photocatalytic conversion route for addressing high concentrations of acetic acid. This process transforms acetic acid into valuable succinic acid through dehydrogenative coupling. Additionally, the photocatalytic conversion of acetic acid exhibits structure sensitivity when employing Pt cocatalysts of varying sizes. Through inhibiting the undesirable H termination of active free radicals over small Pt atoms and clusters, the rate of undesired decarboxylation reactions can be decreased by 75 %. This effectively enhances the selectivity of the coupling product succinic acid by 2.1 times, achieving a succinic acid formation rate of 7.28 mmol/(gcat•h). This work offers a theoretical guidance for searching value-added reaction pathways of acetic acid, thereby establishing an innovative approach for high concentration exhaust acetic acid treatment and converting low value monocarboxylic molecules into valuable diacid polymerization monomers under a mild and green condition.

Enhanced dehydroaromatization of methane with methanol on Mo-ZSM-5/ZSM-11 intergrown zeolite materials

Methane dehydroaromatization (MDA) represents an appealing route for the direct utilization of abundant methane resources. Currently, the major challenge of MDA reaction lies in the rapid catalyst deactivation via coke formation, hindering large-scale industrialization of the process. Herein we report an enhanced conversion route of MDA in the presence of methanol on Mo-based zeolite materials. Compared to regular ZSM-5, ZSM-11, and their mechanically mixed counterparts, Mo embedded in ZSM-5/ZSM-11 intergrown matrix exhibits higher methane conversion (16.0%) and aromatics selectivity (62.5%) while limiting coke production to 12.1% under the co-feeding of methane and methanol (nCH4/nCH3OH = 30). If no methanol addition, coke selectivity is up to 45.1% in MDA reaction. Additionally, hydrogen enriched syngas (nH2/nCO = 6) was obtained as a co-product of the methane and methanol co-aromatization. NH3-adsorbed 1H MAS NMR, Co2+ titrated UV-vis and Raman spectroscopy characterizations reveal that a proper amount of Brönsted acid sites and the binuclear Mo anchored on the Al pairs at the intersection cavity may account for the superior reaction performance of the intergrown zeolites. A catalytic mechanism was also proposed via 13CH3OH isotopic labeling tracer and in-situ13C solid-state NMR studies. Methanol is first decomposed into CO/H2, while CO is hydrogenated to CH4 and converted into CO2 via the water-gas shift reaction. Alternatively, methanol is converted into CO/CO2 through formate intermediates. Subsequently, CO2 reduces coke deposition via the reverse Boudart reaction, which improves the catalytic performance.

Study on Cracking/Oxidation/Integrated Reforming Reaction for Efficient Conversion of Biomass to High‐Quality Syngas

AbstractThe advanced gasification technology of coal is mainly based on oxidation reaction and high temperature but is not suitable for biomass conversion. High tar and CO2 content are the two main issues that affect the efficiency of biomass gasification. In order to deeply convert hydrocarbons/tar and CO2 simultaneously, and enhance syngas yield, the cracking/partial oxidation/reforming reactions and their integrated reaction routes are investigated from an interrelated view. The effects of each reaction on the distribution of C/H elements in hydrocarbons/tar and syngas are illustrated. By cracking and oxidation reaction, the syngas yield can only reach 0.93 Nm3 kg−1, about 58 % of the theoretical maximum value; a large proportion of residual C/H atoms existing in stable hydrocarbons/tar/CO2/H2O are not converted. Based on the concept of lattice O oxidation combined with dry reforming, it realizes syngas yield (CO+H2) 1.56 Nm3 kg−1 with 91.6 % concentration, demonstrating that tar/hydrocarbons and CO2/H2O are converted to syngas efficiently. The effects of [O]/C ratio on gas yield represent a synergistic coordination between lattice Os oxidation and catalytic reforming reaction. Oxidation‐reforming is the optimum route for biomass conversion to high‐quality syngas.

Visualizing Metabolism in Biotechnologically Important Yeasts with dDNP NMR Reveals Evolutionary Strategies and Glycolytic Logic.

Saccharomyces cerevisiae has long been a pillar of biotechnological production and basic research. More recently, strides to exploit the functional repertoire of nonconventional yeasts for biotechnological production have been made. Genomes and genetic tools for these yeasts are not always available, and yeast genomics alone may be insufficient to determine the functional features in yeast metabolism. Hence, functional assays of metabolism, ideally in the living cell, are best suited to characterize the cellular biochemistry of such yeasts. Advanced in cell NMR methods can allow the direct observation of carbohydrate influx into central metabolism on a seconds time scale: dDNP NMR spectroscopy temporarily enhances the nuclear spin polarization of substrates by more than 4 orders of magnitude prior to functional assays probing central metabolism. We use various dDNP enhanced carbohydrates for in-cell NMR to compare the metabolism of S. cerevisiae and nonconventional yeasts, with an emphasis on the wine yeast Hanseniaspora uvarum. In-cell observations indicated more rapid exhaustion of free cytosolic NAD+ in H. uvarum and alternative routes for pyruvate conversion, in particular, rapid amination to alanine. In-cell observations indicated that S. cerevisiae outcompetes other biotechnologically relevant yeasts by rapid ethanol formation due to the efficient adaptation of cofactor pools and the removal of competing reactions from the cytosol. By contrast, other yeasts were better poised to use redox neutral processes that avoided CO2-emission. Beyond visualizing the different cellular strategies for arriving at redox neutral end points, in-cell dDNP NMR probing showed that glycolytic logic is more conserved: nontoxic precursors of cellular building blocks formed high-population intermediates in the influx of glucose into the central metabolism of eight different biotechnologically important yeasts. Unsupervised clustering validated that the observation of rapid intracellular chemistry is a viable means to functionally classify biotechnologically important organisms.

Hydrophobic-treated yolk-shell SnS2@CSs Z-scheme confinement reactor for solar-electro-driven hydrogen peroxide production in neutral media

The diffusion and adsorption properties of the O2/H2O corpuscles at active sites play a crucial role in the fast photo-electrocatalytic reaction of hydrogen peroxide (H2O2) production. Herein, SnS2 nanosheets with abundant interfacial boundaries and large specific areas are encapsulated into hollow mesoporous carbon spheres (CSs) with flexibility, producing a yolk-shell SnS2@CSs Z-scheme photocatalyst. The nanoconfined microenvironment of SnS2@CSs could enrich O2/H2O in catalyst cavities, which allows sufficient internal O2 transfer, improving the surface chemistry of catalytic O2 to O2− conversion and increasing reaction kinetics. By shaping the mixture of SnS2@CSs and polytetrafluoroethylene (PTFE) on carbon felt (CF) using the vacuum filtration method, the natural air-breathing gas diffusion photoelectrode (AGPE) was prepared, and it can achieve an accumulated concentration of H2O2 about 12 mM after a 10 h stability test from pure water at natural pH without using electrolyte and sacrificial agents. The H2O2 product is upgraded through one downstream route of conversion of H2O2 to sodium perborate. The improved H2O2 production performance could be ascribed to the combination of the confinement effect of SnS2@CSs and the rich triple phase interfaces with the continuous hydrophobic layer and hydrophilic layer to synergistically modulate the photoelectron catalytic microenvironment, which enhanced the transfer of O2 mass and offered a stronger affinity to oxygen bubbles. The strategy of combining the confined material with the air-breathing gas diffusion electrode equips a wide practical range of applications for the synthesis of high-yield hydrogen peroxide.

Piston reactor for chemical energy storage: Modeling study to explore electro-mechanical conversion route using propane feedstock

Within the context of renewables and chemical energy storage, this work aims to explore chemical reaction conversion through the electro-mechanical route which is different from the commonly employed electro-thermal and electro-chemical conversion methods. Piston reactor is a novel equipment concept that can couple the rotational movement from an electric motor to a reciprocating piston within an enclosed reaction chamber resembling the operation of an internal combustion engine. Exploration of a reactor technology still in the laboratory stage requires an assessment of reaction intermediate mixtures to identify potential leads. This work uses a systematic methodology to assess these intermediate mixtures beyond typical reactor yield metrics to include economic values as part of the decision-making toward identifying lead candidates. Rather than focusing on a specific target reaction or product, this work is carried out as a model-driven study to cover a wider range of conditions and product scenarios. Propane as the main feedstock is selected because it is easier to trigger in the piston reactor, it is not a complex feed, a detailed kinetic mechanistic model is available to study it, and most importantly it can generate a wide range of industrially relevant products to serve the purpose of this study. The study revealed that the highly endothermic propane pyrolysis reaction requires intake temperatures larger than 950 K which is impractical. Diluting the feed with argon is one way to lower this intake temperature and achieve desirable conversion. This however is impractical because of additional separation steps and reduced production capacity. Thermal coupling of propane pyrolysis with exothermic side reactions by co-feeding oxygen, water, or carbon dioxide are investigated and showed promising results. A diverse range of products are produced such as hydrogen, carbon monoxide, ethylene, and propylene, achieving high conversions (>90 %), while simultaneously generating useful work and process heat. Unconventional triggers such as using ozone to generate radicals and trigger ignition are investigated to further lower the intake temperature requirements. The explored solution space is then evaluated considering a new reactor metric as the value of products mixture stream. Regions of high-value products do not match those obtained using the traditional yield metrics. This shows the importance of what metrics to use for assessing reactors with wide range of reaction mixture intermediates as the piston reactor. Full economic analysis and optimization are the right direction in the future to properly assess the potential of piston reactor technology.