CH4 Yield Research Articles

Utilization of carbon-based nanomaterials for wastewater treatment and biogas enhancement: A state-of-the-art review

The management of environmental pollution and carbon dioxide (CO2) emissions is a challenge that has spurred increased research interest in determining sustainable alternatives to decrease biowaste. This state-of-the-art review aimed to describe the preparation and utilization of carbon-based nanomaterials (CNM) for biogas enhancement and wastewater contaminant (dyes, color, and dust particles) removal. The novelty of this review is that we elucidated that the performance of CNMs in the anaerobic digestion (AD) varies from one system to another. In addition, this review revealed that increasing the pyrolysis temperature can facilitate the transition from one CNM type to another and outlined the methods that can be used to develop CNMs, including arc discharge, chemical exfoliation, and laser ablation. In addition, this study showed that methane (CH4) yield can be slightly increased (e.g. from 33.6% to 60.89%) depending on certain CNM factors, including its type, concentration, and feedstock. Temperature is a fundamental factor involved in the method and carbon sources used for CNM synthesis. This review determined that graphene oxide is not a good additive for biogas and CH4 yield improvement compared with other types of CNM, such as graphene and carbon nanotubes. The efficacy of CNMs in wastewater treatment depends on the temperature and pH of the solution. Therefore, CNMs are good adsorbents for wastewater contaminant removal and are a promising alternative for CO2 emissions reduction. Further research is necessary to determine the relationship between CNM synthesis and preparation costs while accounting for other factors such as gas flow, feedstock, consumption time, and energy consumption.

Torrefaction of combustible construction and demolition waste: Evolution of fuel performance, heavy metal migration and combustion characteristics

Combustible construction solid wastes (CSW) derived from construction and demolition (C&D) wastes is an important part for waste-to-energy system. Torrefaction experiment of five CSW components involving plastic (PL), wood (WD), textile (TX), paper and board (PB), and rubber (RB) were conducted in a fixed-bed reactor at torrefaction temperature of 200–400 °C and holding time of 30 min. Fuel properties and heavy metal migration of CSW components via torrefaction are characterized by proximate analysis, ultimate analysis, caloric value determination, and the determination of heavy metal contents in solid, liquid and gas products. Combustion characteristics of CSW components and their torrefied solid products were evaluated by TG-FTIR method. The obtained results indicated that torrefaction has a significant influence on volatile matter, fixed carbon, calorific value, and H/C and O/C molar ratios of CSW components. The ash content in high ash CSW components increases and energy yield decreases significantly when torrefaction temperature is larger than 250 °C. Heavy metals of Zn, Pb, Cu and Mn in CSW components is partly migrated into the liquid products, but Hg and As are almost entirely present in the liquid products at different torrefaction temperatures. The combustible index and burnout index of PL, WD, PB and RB decrease gradually when torrefaction temperature is more than 250 °C, and the lower yields of SO2, NO, HCl, CH4 and CO of torrefied CSW are achieved at torrefaction temperature of 250 °C. The optimum torrefaction temperature of 250 °C is proposed for improving fuel properties, heavy metal migration and combustion characteristics of CSW components.

Cellulose pyrolysis under NH3 atmosphere for levoglucosan and pyrrole: An experimental and theoretical study

Cellulose pyrolysis for valuable levoglucosan (LG) can improve the value of cellulose utilization. Here, NH3 was introduced into cellulose pyrolysis by a fixed-bed system to investigate the effect of NH3 on the formation of LG and pyrrole, and the reaction pathways of LG and pyrrole formation were explored by combining experimental results with DFT calculations. Results showed that the highest CO yield reached 147.66 mL/g at 800 °C. The yields of H2 and CH4 significantly increased, while CO2 yield decreased. NH3 increased the content of oxygen-containing substances while inhibiting the formation of aromatic and aliphatic hydrocarbons. In addition, some nitrogen-containing products were generated, and their content increased with increasing temperature, among which, the nitrogen-containing products were mainly pyrroles. The content of LG increased about two times, and its absolute yield reached 10.96 wt% at 600 °C, which was about 4.6 times that of direct pyrolysis. DFT calculations showed that NH3 had a promoting effect on cellulose pyrolysis to produce LG, and the reaction energy barrier of the optimal pathway is 194.05 kJ/mol. Cellobiose is transferred to the glycosidic bond O-site by hydrogen transfer from the C2-site to break the glycosidic bond to form the intermediate a4-i1 and glucose. The intermediate a4-i1 was combined with NH3 to form LG via hydrogen transfer, while the resulting glucose was dehydrated to form LG by combining with NH3. For the pathway of cellulose pyrolysis to form pyrrole, NH3 promoted the deoxidation of FF to form furan, and the combination of NH3 with furan promoted furan to undergo a ring-opening reaction more than that of H2O. After the ring opening, the C2 position amino group was linked to the C5 position to form a ring, and the O atom was removed by dehydration with the formation of a hydroxyl group to form pyrrole. The reaction energy barrier for cellulose pyrolysis to form pyrrole under an NH3 atmosphere was 280.08 kJ/mol. It provided a new approach for the preparation of LG and pyrrole from cellulose.

Synergistic effect of CuO and Sr doped g-C3N4 for CO2 photoreduction into hydrocarbon fuels

This study investigates the enhancement of the CO2 photocatalytic reduction (CO2 PR) process, which plays a critical role in sustainable fuel production and alleviates the environmental greenhouse gas emissions. Overcoming the challenges posed by CO2 inertness and sluggish charge carrier kinetics is imperative for efficient CO2 PR. Herein, we explore the role of copper oxide (CuO) and strontium (Sr) nanoparticles as cocatalysts in enhancing the photocatalytic performance of graphitic carbon nitride (g-C3N4) for CO2 reduction. With an emphasis on the often-overlooked selectivity of photo-excited electrons for CO2 reduction with H2O, we find that Sr improves electrical transport characteristics and effectively extracts photo-excited electrons, resulting in an increased CH4 yield rate (0.25 μmol g−1h−1) compared to CN (0.11 μmol g−1h−1). However, Sr decreases CO2 reduction selectivity by accelerating H2O reduction to H2. In addition, introducing CuO in Sr-doped g-C3N4 (SrCN) further enhances CH4 yield while increasing the selectivity for CO2 reduction. The optimized 5CuO@SrCN nanocomposite exhibits a superior CH4 selectivity of 90.34 % with a yield rate of 1.87 μmol g−1h−1, demonstrating the combined effects of CuO coupling and Sr doping in improving light absorption, surface reaction sites, and charge carrier transfer and separation efficiency in CO2 reduction.

Residual methane emissions in grazing lactating dairy cows

ABSTRACT Residual methane emission (RME) is a trait that has previously been identified as being independent of animal production traits. The objective of this study was to investigate the effect of ranking grazing dairy cows by RME on animal productivity and enteric methane (CH4) emissions. Milk production, dry matter intake (DMI), liveweight (LWT) and CH4 were recorded on grazing late lactation dairy cows at Teagasc Moorepark, Ireland. The dairy cows were producing 352 g CH4/day, while consuming 16.6 kg DM. The mean methane yield was 20.79 g CH4/kg DMI. Residual methane emission was calculated as the difference between measured CH4 yield and New Zealand emission factor (21.6 g CH4/kg DMI). These dairy cows were ranked based on their RME and classified into groups. The low RME group produced 15% less CH4 than the high RME group while maintaining milk production and feed conversion efficiency. The low RME group had lower methane yield, and methane intensity. There are no significant phenotypic correlations between RME and animal production traits such as energy corrected milk yield, or LWT. These results indicate that RME has the ability to select and rank low emitting grazing dairy cows while being independent from animal productivity traits.

Copper Modulated Lead‐Free Cs4MnSb2Cl12 Double Perovskite Microcrystals for Photocatalytic Reduction of CO2

AbstractIn order to deal with the global energy crisis and environmental problems, reducing carbon dioxide through artificial photosynthesis has become a hot topic. Lead halide perovskite is attracted people's attention because of its excellent photoelectric properties, but the toxicity and long‐term instability prompt people to search for new photocatalysts. Herein, a series of <111> inorganic double perovskites Cs4Mn1‐xCuxSb2Cl12 microcrystals (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) are synthesized and characterized. Among them, Cs4Mn0.7Cu0.3Sb2Cl12 microcrystals have the best photocatalytic performance, and the yields of CO and CH4 are 503.86 and 68.35 µmol g−1, respectively, after 3 h irradiation, which are the highest among pure phase perovskites reported so far. In addition, in situ Fourier transform infrared (FT‐IR) spectroscopy and electron spin resonance (ESR) spectroscopy are used to explore the mechanism of the photocatalytic reaction. The results highlight the potential of this class of materials for photocatalytic reduction reactions.

Enhanced solar‐light driven CO2 conversion using Pt‐doped graphitic carbon nitride photocatalyst

AbstractThe increasing levels of carbon dioxide (CO2) in our atmosphere demand innovative and efficient methods for its reduction. In this context, we present an advanced solar‐driven photocatalyst, Pt‐doped graphitic carbon nitride (Pt/g‐C3N4), specifically engineered for enhanced photoreduction of CO2. Our findings highlight the dual advantage of Pt/g‐C3N4: enhanced visible light absorption and electron‐hole pair dynamics, ensuring efficient carrier separation. Notably, the CO and CH4 yields, when employing Pt/g‐C3N4, surpassed those with the pristine g‐C3N4 catalyst by factors of 3.1 and 4.3, respectively. Moreover, the Pt/g‐C3N4 catalyst exhibited consistent high‐efficiency of CO2 conversion over successive cycles, emphasizing the catalyst's robustness. This work underscores the potential of Pt/g‐C3N4 as a viable tool against escalating CO2 levels, paving the way for a green and sustainable conversion of this predominant greenhouse gas into beneficial chemicals. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Methane prediction equations including genera of rumen bacteria as predictor variables improve prediction accuracy

Methane (CH4) emissions from ruminants are of a significant environmental concern, necessitating accurate prediction for emission inventories. Existing models rely solely on dietary and host animal-related data, ignoring the predicting power of rumen microbiota, the source of CH4. To address this limitation, we developed novel CH4 prediction models incorporating rumen microbes as predictors, alongside animal- and feed-related predictors using four statistical/machine learning (ML) methods. These include random forest combined with boosting (RF-B), least absolute shrinkage and selection operator (LASSO), generalized linear mixed model with LASSO (glmmLasso), and smoothly clipped absolute deviation (SCAD) implemented on linear mixed models. With a sheep dataset (218 observations) of both animal data and rumen microbiota data (relative sequence abundance of 330 genera of rumen bacteria, archaea, protozoa, and fungi), we developed linear mixed models to predict CH4 production (g CH4/animal·d, ANIM-B models) and CH4 yield (g CH4/kg of dry matter intake, DMI-B models). We also developed models solely based on animal-related data. Prediction performance was evaluated 200 times with random data splits, while fitting performance was assessed without data splitting. The inclusion of microbial predictors improved the models, as indicated by decreased root mean square prediction error (RMSPE) and mean absolute error (MAE), and increased Lin’s concordance correlation coefficient (CCC). Both glmmLasso and SCAD reduced the Akaike information criterion (AIC) and Bayesian information criterion (BIC) for both the ANIM-B and the DMI-B models, while the other two ML methods had mixed outcomes. By balancing prediction performance and fitting performance, we obtained one ANIM-B model (containing 10 genera of bacteria and 3 animal data) fitted using glmmLasso and one DMI-B model (5 genera of bacteria and 1 animal datum) fitted using SCAD. This study highlights the importance of incorporating rumen microbiota data in CH4 prediction models to enhance accuracy and robustness. Additionally, ML methods facilitate the selection of microbial predictors from high-dimensional metataxonomic data of the rumen microbiota without overfitting. Moreover, the identified microbial predictors can serve as biomarkers of CH4 emissions from sheep, providing valuable insights for future research and mitigation strategies.

One-pot hydrothermal preparation of Ni and I co-doped brookite-anatase TiO2 nanoparticles with remarkably enhanced photoreduction activity of CO2 to CH4

Ni and I co-doped TiO2 nanoparticles with mixed anatase-brookite phase (Ni/I-TiO2) were synthesized by the hydrothermal-calcination method for photocatalytic CO2 reduction with H2O vapor. The I and Ni co-doping, anatase-brookite phase junction, as well as the presence of Ti(III) and Ni(III) endowed the catalyst with promoted visible light absorption, increased reduction ability of photogenerated electrons, facilitated charge separation and migration along with modulated CO2 adsorption mode and capacity, ultimately resulting in boosted photocatalytic activity and product selectivity as compared with those of pure TiO2. The CO, CH4 and O2 yields of the optimized Ni/I-TiO2 reached 3.49, 158.25 and 246.30 μmol/gcat after 15 h of light illumination, which decreased slightly after 9 cycles, and the product selectivity was above 98 % for photocatalytic reduction of CO2 to CH4 with Ni and I co-doping. The in-situ FTIR results with the observation of CH3O and CH3 intermediates confirmed CH4 formation, and the possible mechanism of photocatalytic CO2 reduction over Ni/I-TiO2 was elucidated. This work provides new insights to pursue efficient catalysts for the selective photocatalytic CO2 reduction to CH4.

Synergistic conversion of iron ore sintering dust and waste biochar to produce direct reduction iron and syngas: Gasification, reduction behavior and thermodynamic analysis

Waste biochar from biomass power generation and sintering dust from ferrous metallurgy were skillfully used to produce direct reduced iron (DRI) and syngas via a synergetic conversion in this study. The thermodynamic analysis of their related reactions, biochar conversion and reduction behavior of sintering dust were investigated. The biochar gasification and reduction of sintering dust were coupled and promoted by each other at 1000 °C for 60 min with 1.2 mol (C/Fe). For biochar conversion, adding sintering dust deepened the pyrolysis of the volatiles in the waste biochar to generate more CH4, and it provided more oxygen atoms, gasifying carbon atoms in the fixed carbon to generate more CO. The CO and CH4 yield from biochar conversion with iron oxides of sintering dust increased by 633.8% and 41.5% to its pyrolysis alone. For the reduction of sintering dust, the whole conversion process of sintering dust was the generation, aggregation and growth of the iron grains, including the generation of metallic iron grains, forming curved bars and composite flocculent metallic iron, and its larger lumps particles finally. A DRI with a 92.4% metallization ratio, meeting the requirements of the subsequent electric arc furnaces, was obtained at 1000 °C for 60 min with 1.2 mol (C/Fe). This study achieves an efficient and reciprocal conversion of these two solid waste resources. It offers an essential research reference for fuel gasification and DRI processes.

Sr Promoted Ni/W-Zr Catalysts for Highly Efficient CO2 Methanation: Unveiling the Role of Surface Basicity.

This study explores the employment of CO2 methanation for carbon dioxide utilization and global warming mitigation. For the first time, in this work, we combine the interesting properties of the WO3-ZrO2 support and the benefits of Sr to improve the performance of Ni-based catalysts in this reaction. Sr loading on 5Ni/W-Zr samples is increased to 3 wt %, resulting in improved surface basicity through strong basic site formation. After 300 min, the 5Ni + 3Sr/W-Zr catalyst exhibits high activity and stability, achieving 90% CO2 conversion and 82% CH4 yield compared to 62 and 57% on 5Ni/W-Zr. Limited sintering and absence of carbon deposits are confirmed by temperature-programmed oxidation, XRD, Raman, and TEM analyses at 350 °C for 300 min. Sr promotion creates additional CO2 adsorption and conversion sites, enhancing the catalytic performance.

Matched micro-geometrical configuration leading to hetero-interfacial intimate contact of MoS2@UiO-66-NH2 Z-scheme heterojunction for efficient photocatalytic CO2 reduction

Z-scheme heterojunction is an effective strategy in photocatalysis, when hetero-interfacial intimate contact is the center of high-performance Z-scheme heterojunction structure. Here, x-MoS2 [x = plate (p), flower (f), and solid sphere (s)] with extensive optical absorption and high conductivity and stable UiO-66-NH2(y) (y = 100, 300, and 500 nm) with rich Lewis's acid sites were integrated to a series of x-MoS2@UiO-66-NH2(y) Z-scheme heterojunctions, which were fully characterized and used for photocatalytic reduction of CO2 (pCO2RR) into CH4 and CO. In response to the difficult modification of MoS2 and loose contact of composite bulk materials, the micro-geometric configurations on the size of UiO-66-NH2 and the morphology of MoS2 were optimized to achieve an intimate contact. The Z-scheme heterojunction f-MoS2@UiO-66-NH2 (100 nm) with perfectly matched micro-geometric configuration exhibited an excellent electron consumption rate (Rele) of 263.78 μmol g–1 h–1 and a high CH4 yield of 27.18 μmol g–1 h–1 with a selectivity of 82.44%, being far superior to most MoS2- and MOFs-based heterojunctions. Comprehensive investigations with extensive photoelectric characterizations, control experiments, and density functional theory (DFT) calculations demonstrate that the excellent photocatalytic performance of f-MoS2@UiO-66-NH2 (100 nm) could be attributed to that (i) the low size of UiO-66-NH2 strengthens mutual alignment and increases outer surface to maximize heterointerface contact with MoS2, accelerating the interfacial charge transfer; (ii) the hierarchical structure of f-MoS2 with optimal basal plane curvature greatly reduces contact barriers to present a high charge throughput with a charge excitation rate of 1.967 mV, smooth initiating the 8-electron CO2 methanation. Additionally, the durability of f-MoS2@UiO-66-NH2 (100 nm) was also investigated.

Reinforcing flower-like Znln2S4 via interfacial charge separation to boost CO2 photoreduction

CO2 Photoreduction through C–O bond cleavage and C–H bond formation has aroused as an alternative to fabricate high-value chemical fuels that are independent of fossil reserves. However, sluggish charge transfer and neglected light-induced heat utilization are thermodynamically and kinetically challenging. Herein, we subtly design a three-dimensional ultrathin composite consisting of flower-like ZnIn2S4 (ZIS) and low-cost biochar (BC). The as-prepared ZIS/BC photocatalyst displays an optimized performance and stability toward CO2 conversion, with a high CO yield of 20.7 μmol g−1 h−1 and a small yield of CH4, C2H4, and C2H6 in comparison with ZIS and BC counterparts. This exciting activity originates from high electron conduction efficiency, light-harvesting ability, and the photothermal effect, which is produced from the intense interfacial contact of BC and ZIS. This work suggests that traditional photocatalysts can be elevated by inhibiting photocorrosion by introducing highly economical and electron conductivity biomass carbon in solar-induced green-chemical feedstock production.

Fabricated S-scheme BiOBr/Cu2O heterojunction photocatalyst for adjusting conversion of CO2 to CH4

The preparation of heterojunction photocatalysts with staggered energy band structures and proper interfacial contacts is an effective way to improve CO2 conversion. This study adopted a simple hydrothermal method to form Cu2O on the surface of BiOBr, and s scheme BiOBr/Cu2O heterojunctions with close contacts were constructed. The rate of CO2 reduction over the catalyst was tested in a gas-solid reactor simulating sunlight. The results show that the BiOBr/Cu2O composite moderately yields CH4 with an efficiency of 22.78 μmol g−1h−1 for conversion from CO2 to CH4 in visible light, while pure BiOBr yields only CO. In addition, Transient photocurrent response, Electrochemical impedance spectroscopy, and Photoluminescence measurements demonstrated that the BiOBr/Cu2O had a strong photogenerated carrier transfer and separation and high photo-availability, while key intermediates favoring CH4 yield were found by in situ IR. Finally, the possible photocatalytic mechanism was explored based on the energy band structures of BiOBr and Cu2O in the characterization.

Indications for a lower methane yield from digested fibre in ruminants digesting fibre more efficiently

It is assumed that the absolute amount of methane (CH4) produced on a given diet increases proportionately (i.e., in a linear manner) with the amount of digested fibre. Therefore, the CH4 yield per unit of digested fibre is considered constant for a given diet. This conceptually matches findings of lower digestibility in low-CH4 emitting animals, and of lower CH4 yield at higher intake levels due to shorter digesta passage and hence reduced digestibility. Irrespective of these observations, this general assumption was challenged by findings in one study where CH4 yield per unit of digested fibre had unexpectedly declined in individuals digesting the fibre provided by the same diet more efficiently. To investigate this finding in more detail, we collated a dataset from 16 studies with cattle and sheep with a total of 61 forage-based diet groups consisting of at least five animals each (472 animals in total). We assessed whether there was a linear relationship between the daily CH4 emission and the amount of digested fibre, both within the same and across the different diet groups. Across diets, CH4 emissions did not increase linearly with the amount of digested neutral or acid detergent fibre in either species. Within diet groups, the majority of cases also showed evidence for less-than-linear increase of CH4 emissions with increasing amount of digested neutral or acid detergent fibre, even though the 95 % confidence intervals could not rule out a linear relationship in many cases. Reasons why this phenomenon was not described earlier may include that the great individual variation associated with an accumulation of errors in the variables concerned often prevented statistical significance in individual studies. Although the findings across diets concerning the variation in CH4 yield per unit of digested fibre do not exclude some diet-specific effects, the within-diet assessment clearly points towards individual animal effects in microbial fibre digestion in a way that CH4 production is proportionately lower when fibre is digested more efficiently. Mechanistically, animals with a more efficient fibre digestion might produce volatile fatty acids at a higher rate and have a locally lower ruminal pH, favouring microbiota of propionate-producing pathways. The presence of animal-individual differences in CH4 yield per unit of digested fibre with varying efficiency of fibre fermentation should be confirmed in a specific experiment where also the reasons for such a phenomenon are further investigated.

Co-enhancing effects of zero valent iron and magnetite on anaerobic methanogenesis of food waste at transition temperature (45 °C) and various organic loading rates

Deoiling of food waste (FW) after hydrothermal pretreatment occurs at high temperatures, and more energy is required for substrate cooling before the anaerobic digestion (AD) process. AD at the transition temperature (for example 45 °C) is good for energy saving and carbon emission reducing when treating deoiling FW. However, the metabolic activity of methanogens must increase at the transition temperatures. This study proposes the use of zero-valent iron (Fe0) and magnetite (Fe3O4) to boost CH4 yield from deoiling FW. The results showed a co-enhancing effect on CH4 yield upgradation when using Fe0 and Fe3O4 simultaneously, and the highest CH4 yield reached 536.23 mLCH4/gVS, which was 67.5 % higher than that of Fe0 alone (320.14 mLCH4/gVS). In addition, a high organic loading was favorable for increasing the CH4 yield from deoiling FW. Microbial diversity analysis suggested that the dominant methanogenic pathway at 45 °C was hydrogenotrophic methanogenesis. Herein, a potential metabolic pathway analysis revealed that the co-enhancing effects of Fe0 and Fe3O4 enhanced syntrophic methanogenesis and possibly boosted electron transfer efficiency.

CO2 reduction employing MgH2 for CH4–H2 mixtures production through mechano-chemical processes

The CO2 methanation employing MgH2 as a source of hydrogen is investigated via mechano-chemical processes through ball milling at room temperature under different experimental conditions such as the presence/absence of catalyst, the milling duration, the molar ratio between the hydride and CO2 and the pre-milling of Ni–MgH2 mixture. The positive effect of Ni addition is demonstrated. After 5h of milling under CO2, the absence of catalyst causes the CH4 yield to drop from 70.0 to 59.0%, from 73.0 to 33.5% and from 54.0 to 40.1%, considering molar ratios of 4:1, 3:1 and 2:1, respectively. The pre-milling of nickel-catalyzed system or the addition of CNTs do not provide significant improvements. This investigation shows that similar methane yields to those obtained by thermo-chemical methods can be achieved, but involving shorter times (5 h versus 24 h) and lower temperatures (room temperature versus 400 °C). The ball collisions during milling allow overcoming passivation phenomena of MgH2 and Mg, promoting the methanation process but with lower selectivity as contamination with Fe from the milling jar provides a catalytic alternative route for the generation of C2–C3 hydrocarbons.

Solar light promoted CO2 hydrogenation to CH4 over photo-thermal responsive dispersed Co on defective CeO2 composite derived from MOFs

The conversion of the greenhouse gas CO2 represents a pragmatic and environmentally friendly approach. However, the substantial energy demands of the reaction hamper its widespread application. Here, we designed an efficient catalyst prepared by Ce-MOF and ZIF-67 precursor, namely Co/CeO2, for photothermal CO2 methanation under light and auxiliary heating. CeO2 synthesized by Ce-MOF has a good structure and abundant oxygen vacancies, meanwhile, Co has abundant active sites and strong adsorption capacity and is well-dispersed on CeO2. As a result, the catalyst exhibits high CH4 yield of 885.27 mmol⋅g−1⋅h−1 and CO yield of 24.5 mmol⋅g−1⋅h−1. Moreover, it has good selectivity and catalytic durability. Through the analysis of the reaction pathway under the conditions of photothermal catalysis, the hydrogenation reaction of formate can efficiently generate CH4 and H2O due to the promotion of hot carriers. This work demonstrated the advantages of photothermal co-catalysis and provides a potential strategy for efficient CO2 reduction.

Enhancing co-gasification gas yield prediction in downdraft gasifiers through statistical correction strategy

Compared to typical gasification methods, the co-gasification method can change syngas composition by adjusting feedstocks and mixing ratio, but predicting gas yield in co-gasification is often more difficult. As a typical gasification equipment, the downdraft gasifier is commonly used to conduct experimental studies on co-gasification. For this reason, a novel co-gasification gas yield prediction method combined with the statistical correction strategy is proposed utilizing a downdraft gasifier as the gasification equipment. The statistical correction strategy is implemented by the statistically based error correction method and uncertainty classification of gasification conditions. The co-gasification dataset of the downdraft gasifier was built to test the proposed method. The results demonstrate that the statistical correction strategy is effective, and the proposed method can forecast co-gasification gas yields accurately, with prediction models achieving R2 of 0.9418, 0.9842, 0.8952, and 0.9822 for H2, CH4, CO, and CO2 yields, respectively.

ZnIn2S4/TiO2 photocatalyst for CO2 photoreduction: Advancing sustainable energy conversion to renewable solar fuels

The rapid increase in CO2 concentration in the atmosphere raised global climate challenges, which creates attention for the researcher to mitigate CO2 from the atmosphere so that the environment can be sustained for generations. From the photocatalysis perspective, reducing CO2 into carbon monoxide (CO) and methane (CH4) is a promising pathway for sustainable solar fuel production. Here, we fabricated a heterojunction nanocomposite photocatalyst of ZnIn2S4 and TiO2. The photocatalyst was highly efficient for CO2 reduction with 1754 and 481 μmol/g yields of CO and CH4, respectively. The photocatalyst had excellent photocatalytic activity and was stable for five consecutive experiments without significant activity loss. The potential of ZnIn2S4/TiO2 photocatalyst to revolutionize carbon monoxide production for various applications underscores its significance in advancing sustainable carbon mitigation strategies.