Total Gas Yield Research Articles

Comprehensive experimental assessment of biomass steam gasification with different types: correlation and multiple linear regression analysis with feedstock characteristics

In order to reveal the correlation between gasification behavior and products with feedstock characteristics, the steam gasification of 13 biomasses was investigated using a thermogravimetric analyzer and a fixed-bed reactor. Meanwhile, a multiple linear regression was used to construct correlation models. The results showed that cellulose content and crystallinity had the greatest influence on pyrolysis reactivity, which was reflected that the cellulose content was strongly positively correlated with the pyrolysis reactivity (Pmax = 0.77), while the lignin content and cellulose crystallinity were opposite. H/C, O/C ratios and SiO2 content had the greatest influence on gasification stage. O/C were strongly negatively correlated with gasification reactivity (Pmax = −0.81). But correlations of K and Ca contents were much less than that of Si. Husk has the best gasification performance than straw and woody with highest H2 and total gas yield of 28.26 and 68.93 mmol·g−1. H2 concentration and yield were significantly affected by the cellulose crystallinity and the fixed carbon content with positively correlation (P = 0.69–0.85). CH4 and CnHm were also influenced by them, but the trend was opposite to that of H2. Cellulose content, followed by SiO2 content mainly affected CO and CO2 and negatively correlated with CO while positively with CO2.

ANN model of co-gasification process in bubbling fluidized bed: Contribution ratio analysis

Co-gasification of coal and biomass in a bubbling fluidized bed may offer an effective and economical method to partially replace coal to produce hydrogen, thereby addressing the objectives of achieving a carbon dioxide emissions peak and carbon neutrality. An Artificial neural network (ANN) model was utilized to simulate the hydrogen and other performance of co-gasification in the bubbling fluidized bed. Five types of ANN architectures were tested, including FFBP, CFBP, EFBP, LR, and NARX. Five optimization algorithms were also applied, including L-M, GA, GD, GDX, and PSO, to identify the optimal model to give a more accurate predicate the hydrogen production. The input data were derived from the ultimate analysis of the mixed coal and biomass, the proximate analyzes of mixed coal and biomass, and the operational conditions. The output data consisted of gas composition, carbon conversion, gasification efficiency, total gas yield, syngas yield, low and high heating values of the gas. The LR-PSO with 6 hidden neurons (R2 = 0.9995 and MSE = 0.1357) outperformed other ANN types and optimization algorithms. To further understand the performance of co-gasification, the influences of biomass to coal ratio, equivalence ratio, steam to carbon ratio and temperature on ratio of H2 to CO and syngas yield were predicted. The highest ratio of H2 to CO for the work of Li et al. (2010) [26], Song et al. (2013) [27] and Valdés et al. (2015) [28] were 0.7, 1.2 and 0.88, respectively. And those for syngas yield were 0.85, 1.09 and 1.55 m3/kg, respectively. To reveal the important factor on the ratio of H2 to CO, a detailed analyzed of the contribution ratio was conducted. The most critical factor affecting co-gasification performance in the work of Song et al. (2013) [27] were identified as SC ratio and temperature, which was higher than those of W and ER. The effect of SC exceeded that of T at SC ratio of 0.4, while it came to a reverse at temperature above 700 °C. These findings may serve as a valuable tool for adjusting the various factors to achieve the desired performance in the co-gasification of coal and biomass.

Investigation on the thermochemical characteristics, kinetics and evolved gases for typical kitchen waste pyrolysis

Kitchen waste is a complex biomass waste, whose composition and properties vary with factors such as source, season and region. It is challenging to classify and characterize it. A thermogravimetric and kinetic study was performed to estimate pyrolysis characteristics and gas emissions of starch, peel, nut shell, and vegetables. Samples underwent pyrolysis in the Simultaneous Thermal Analysis from room temperature to 1200 K at different heating rates of 10, 20, 30 and 50 K/min. The starch had the narrowest pyrolysis temperature range, while nut shell exhibited the highest residual rate. The average activation energy for pyrolysis process calculated using Coats–Redfern method was in order of starch > vegetable ≈ nut shell > peel. The gaseous products and typical functional groups of the released volatiles were identified using specific information from Fourier Transform Infrared Spectroscopy (FTIR) and Mass Spectrometry (MS). These primarily included small inorganic molecules, aldehydes, aromatics, ethers, furans, ketones, organic acids, and phenols. Aliphatic hydrocarbons significantly contributed to the total gas yield and were the most abundant for all samples. The characteristic ion fragment with m/z = 60 was only observed in peel and nut shell, while m/z = 58 ion fragments were exclusive to starch and vegetables. The practical research can provide theoretical basis for the resource utilization and environmental management of kitchen waste.

Methane production from locally available ruminant feedstuffs in Ethiopia – An in vitro study

Achieving optimal nutrient composition in locally sourced ruminant feeds is important, but can be challenging in resource-limited production systems. For example, improving the composition of available local feed resources is a key obstacle to efficiently mitigating enteric methane (CH4) emissions in ruminants. This study characterized the nutritional content and in vitro methane (CH4) yield of ruminant feedstuffs accessible in Ethiopia. A survey of 60 experienced farmers in two representative districts in Amhara region, Ethiopia, provided 33 feed samples, which were classified into four ruminant feed categories: Grasses (n=10); indigenous plants (trees, shrubs, herbaceous plants) (n=13); crop residues (n=5); and agro-industrial by-products (n=5). Nutritional composition was assessed by proximate and detergent methods. Methane yield (g CH4/kg feed dry matter (DM)) and total gas yield (L/kg DM) were evaluated using a fully automated in vitro gas production system. A colorimetric assay was conducted to measure condensed tannin content (CT, mg/g) in relevant feeds. Lower crude protein (CP) values were observed for the grass (mean 65.2 g/kg DM) and crop residues (mean 54.5 g/kg DM) categories. Agro-industrial by-products had the highest CP (mean 260 g/kg DM), while indigenous plants exhibited intermediate levels (163 g/kg DM). There was significant variation in CH4 yield (P<0.01) between grasses (12.4–24.7 g/kg DM) indigenous plants (1.8–19.3 g/kg DM), and agro-industrial by-products (8.1–26.9 g/kg DM). The indigenous plant Trifolium acaule gave the lowest in vitro CH4 yield (1.8 g/kg DM). A positive relationship was observed between in vitro dry matter digestibility (IVDMD), CH4, and total gas yield. Percentage of CH4 in total gas production varied with feed category (grasses 14.5–19.6%; indigenous plants 3.1–16.9%; crop residues 15.8–20.6%; agro-industrial by-products 12.8–18.7%), and within category, e.g., Trifolium acaule (3.1%), Acacia nilotica L. (7.1%), Ziziphus spina-christi (9.9%), brewer’s spent grains (BSG) (12.8%), local liquor (areki) residues (14.1%), and local beer (tella) residues (15.1%). A negative relationship was observed between CT content and in vitro CH4 yield, with a stronger (P<0.05) correlation for soluble CTs (R2 = 0.46) than cell-bound CTs (R2 = 0.25) and total CTs (R2 = 0.29). Based on methanogenic properties and effects of CTs on in vitro CH4 yield, indigenous plants should be prioritized in ruminant rations in Ethiopia. Making nutritional composition and CH4 data publicly available could help develop environmentally sound, cost-effective rations for ruminant livestock, benefiting local farmers and leading to more sustainable and efficient livestock production in Ethiopia.

Study on mechanism of supercritical water gasification of hemicellulose for hydrogen-rich syngas based on experiments and reaction molecular dynamics simulations

Hydrogen-rich syngas from supercritical water gasification (SCWG) of renewable biomass is a promising technology. However, the mechanistic studies related to experiments and simulations on hemicellulose, an important component of biomass, are still limited. Therefore, in this study, the SCWG mechanism of hemicellulose was investigated using a batch reactor and via ReaxFF molecular dynamics simulations. The results indicated that the long chains of xylan broke to short chains during the heating process, which was accompanied by the occurrence of ring-opening reactions. SCWG occurred more completely with increasing temperature or decreasing concentration, when hydrogen was more selective and methane was produced mainly by gas reforming reactions. At 600 °C and 5 g/100 g water, the total gas yield of xylan SCWG was 38.65 mmol g−1, and the hydrogen yield could reach 14.48 mmol g−1. The liquid products mainly included furfural and phenol. The solid products consisted of a high C content, which could reach more than 90 % at 500 °C, and were dominated by polycyclic aromatic hydrocarbons, and at 600 °C by benzene and naphthalene. Xylan formed carbon balls on the surface of the solid products, while hemicellulose exhibited the formation of a dense porous structure.

Understanding the conversion mechanisms in supercritical water conditions of PET as a model compound of plastic wastes

In this work, polyethylene terephthalate (PET) was used as a model compound for understanding the conversion mechanism of plastic wastes through supercritical water gasification (SCWG) for producing: i) a gas rich in methane/hydrogen; and ii) for obtaining valuable molecules to be recycled in chemical processes (e.g., benzoic and acetic acids).The experiments were conducted at two different temperatures (above the critical point of water): 450 °C and 600 °C, in order to study the influence of this parameter on the conversion yield. The holding time in the reactor was set at 30 min for all trials. The experimental data were compared to the thermodynamic equilibrium calculations and the results showed that increasing the temperature from 450 °C to 600 °C, the total gas yield is highly improved (from 8.6 mol gas/kg of dried feedstock to 22 mol gas/kg of dried feedstock). The experiments with Raney-nickel catalyst indicated a significant improvement of the carbon conversion yield, which led to a higher gas production from mild to higher temperatures. The maximum total gas yield obtained with this catalyst was 63.4 mol gas/kg of dried feedstock at 600 °C, which is almost 3 times higher than that obtained at the same operating conditions without catalyst. The HHV of the obtained gas at 600 °C with the catalyst was 64.7 MJ/kg gas and 57.9 MJ/kg gas at 450 °C. Additionally at mild operating temperatures (450 °C), the obtained performance with the catalyst was even higher than that obtained at 600 °C without catalyst (50 mol gas/kg dried feedstock and 22 mol gas/kg dried feedstock, respectively), which is the major contribution of this work. At mild temperatures (450 °C) the methane production is highly favored, meanwhile at 600 °C the hydrogen production is enhanced. The methane yield obtained at 450 °C was 21.3 mol CH4/kg dried feedstock and the hydrogen yield obtained at 600 °C was 20.6 mol H2/kg dried feedstock. In the aqueous phases obtained from the experiments performed without catalyst at 450 °C, it was found valuable intermediate species such as benzoic and acetic acids (at a concentration of 4462 mg/L and 946 mg/L, respectively). This study represents a sustainable approach for valorizing plastic wastes by catalytic SCWG process.

Test operation of microwave-assisted chemical looping gasification for water hyacinth with a lean iron ore as oxygen carrier

Chemical looping gasification has been considered as a promising biomass energy conversion technology for syngas production. In this work, a novel microwave-assisted chemical looping gasification (MACLG) reactor system is applied to water hyacinth with a lean iron ore as the oxygen carrier (OC). This approach is expected to achieve effective gasification performance with fast heating and small temperature fluctuation. MACLG can promote the proportion of syngas to 74.39%, lower heating value to 11.83 MJ/Nm3 and cold gasification efficiency to 80.94%. In addition, the increase of OC has a great effect on the conversion of water hyacinth. Favorable gasification performance, including total gas yield, H2/CO ratio, carbon conversion efficiency, and OC reactivity, can be achieved when the molar ratio of Fe2O3/C is in the range of 0.25–0.50. Furthermore, a moderate temperature is also vital for reaction effect. With a temperature of 900 °C, the highest H2/CO ratio of 1.37 of syngas is obtained.

Synergistic interactions between cellulose and plastics (PET, HDPE, and PS) during CO2 gasification-catalytic reforming on Ni/CeO2 nanorod catalyst

CO2 gasification-reforming is a promising approach for the transformation of carbonaceous materials into CO-rich syngas. Within municipal solid waste and agricultural waste streams, plastics are commonly found intermixed with biomass waste. This study delves into the CO2 gasification-reforming of biomass (cellulose) and various plastics (PET, HDPE, and PS) using a self-built online weighing fixed bed reactor and a two-stage fixed bed reactor. During the gasification-reforming of cellulose-plastic mixtures without the catalyst, the experimental gas production rate of cellulose slightly decreased, with the peak of gas production migrating to a higher temperature range. This phenomenon can be attributed to the molten plastic adhering to the cellulose surface, which impeded heat and mass transfer essential for cellulose decomposition. Furthermore, the gas production from plastics was suppressed in the mixtures, likely due to the interference of cellulose char in the decomposition of plastics. The incorporation of 2%Ni/CeO2 catalysts not only augmented gas yields and production rates but also emphasized the synergistic interactions. For the cellulose-HDPE mixture, the total gas yield was reduced by 14.9 mmol gsample−1 relative to the theoretical value. Given that HDPE possessed the highest decomposition temperature, the synergistic interaction was predominantly driven by the inhibitive nature of cellulose char. In contrast, the total gas yields for cellulose-PET and cellulose-PS mixtures increased by 8.7 mmol gsample−1 and 13.3 mmol gsample−1, respectively. The free radicals emanating from cellulose could trigger the decomposition of volatile components from plastics. Concurrently, the decomposition products of plastic could serve as hydrogen donors to stabilize the volatiles of cellulose. The interactions primarily affect the volatiles and tar components of the mixtures. The catalysts amplified gas yields by facilitating the CO2 reforming of tar, therefore, the synergistic interaction became evident upon catalyst addition. Gas chromatography-mass spectrometry analyses of the tar also corroborated the described interaction mechanisms between cellulose and plastics. Thermogravimetric analysis of used catalysts indicated that the synergistic action between cellulose and plastic could effectively diminish coke deposition, thereby preventing swift catalyst deactivation.

Prediction of syngas yield from biomass by gasification and related application

This research focuses on the prediction of synthesis gas generation from biomass through gasification and specifically estimates the syngas yield from rice straw from 2018 to 2020. The data of 2020 is visualized in the form of a colored world map A comprehensive literature review is conducted to explore previous studies on syngas yield models and gasification methods and the utilization of machine learning models. A machine learning model is built to calculate the prediction of the syngas total yield generated from biomass gasification. The inputs of the model include temperature, carbon content, hydrogen content, and oxygen content, with the latter three representing different types of biomasses. The output of the model is the total synthesis gas yield per kilogram of biomass. Subsequently, this model is utilized to predict the amount of syngas obtained from rice straw, which has a carbon, hydrogen, and oxygen content of 43.9%, 5.6%, and 32.1% respectively. From the model, an optimal gasification temperature of 667 degrees Celsius and a maximum syngas yield of 4.71 Nm3/kg for rice straw is obtained. Based on available data on rice straw production worldwide from 2018 to 2020, the amount of rice straw utilized for biomass gasification is estimated. The syngas yield in different regions of the world is calculated based on the maximum syngas yield and the mass of available rice straw. Outcomes of the calculation are visualized into a global map displaying the distribution of syngas yields which provides valuable insights into the potential for syngas production from rice straw in different regions.

Hydrogen production from supercritical water gasification of canola residues

Canola hull, meal and straw are abundantly available as low-value agricultural residues in Canada. These lignocellulosic feedstocks have the potential for the generation of biofuels as alternatives to fossil fuels. Supercritical water gasification is an emerging hydrothermal process for the conversion of recalcitrant biomasses into value-added hydrogen with the application of water beyond its critical temperature and pressure. This study focuses on the comparative investigation of supercritical water gasification of canola residues for H2 production through optimization of process temperature (350–500 °C), reaction time (20–80 min) and feedstock concentration (10–25 wt%) at a constant pressure of 23–25 MPa. Supercritical water gasification of canola straw resulted in a high H2 yield of 7.1 mmol/g to 6.2 mmol/g of H2 from canola hull and 5.5 mmol/g of H2 from canola meal at a temperature, reaction time and feedstock concentration of 500 °C, 40 min and 20 wt%, respectively. Furthermore, H2 yield and total gas yield from canola straw were maximized to 8.1 mmol/g and 29.7 mmol/g at the optimized supercritical water gasification conditions of 500 °C, 60 min and 10 wt%. Hydrochar obtained at high gasification temperatures also revealed aromatic carbon structures and thermal stability due to dehydrogenation, decarboxylation, deamination and aromatization. The overall results demonstrated the potential of supercritical water gasification as an evolving hydrothermal process to convert lignocellulosic biomass into high-value H2-rich gas.

High quality syngas production from catalytic steam gasification of biomass with calcium-rich construction waste

High quality syngas was produced by steam gasification of biomass waste with catalyst derived from disposable calcium-rich construction waste after calcination (C-CCW) at high temperature. The effects of biomass gasification parameters including operating temperature, catalyst loading amount and biomass varieties on characteristics of biomass steam gasification were studied. Experiment results indicate that the total gas yield of produced gas derived from steam gasification of corn stalk increased markedly with elevated reaction temperature and catalyst loading amount. Addition of C-CCW on biomass significantly promoted the decomposition of tar in syngas during steam gasification resulting in higher gas yield and better gas quality. The considerable H2 yield (29.70 mmol/g-biomass), CO yield (4.14 mmol/g-biomass), CH4 yield (3.40 mmol/g-biomass), and H2/CO mole ratio (7.17) were achieved after steam gasification of corn stalk with 10.0 wt% C-CCW at 750 °C. There were significant differences in steam gasification performance of different biomass samples owed to the properties of biomass feedstock. Distinct saturation capacities of C-CCW loading amount were observed for enhancing gasification and eliminating tar during steam gasification of diverse biomass feedstocks. C-CCW appeared to have comparable catalytic effect to that of pure CaO and therefore could be an alternative of calcium-containing catalyst.

Metal-THINGS: a panchromatic analysis of the local scaling relationships of the dwarf irregular galaxy NGC 1569

ABSTRACT We investigate several panchromatic scaling relations (SRs) for the dwarf irregular galaxy NGC 1569 using Integral Field Unit (IFU) data from the Metal-THINGS Survey. Among the spatially resolved properties analysed, we explore SRs between the stellar mass, SFR, molecular gas, total gas, baryonic mass, gas metallicity, gas fraction, SFE, and effective oxygen yields. Such multiwavelength SRs are analysed at a spatial resolution of 180 pc, by combining our IFU observations with data from the surveys THINGS, CARMA, and archival data from DustPedia. Although we recover several known relations, our slopes are different to previously reported ones. Our star formation main sequence, Kennicutt–Schmidt (KS), and molecular KS relations show higher SFRs, lower scatter, and higher correlations, with steeper (1.21), and flatter slopes (0.96, 0.58), respectively. The shape of the SRs including metallicity, stellar mass, and gas fraction are flat, with an average value of 12 + log(O/H) ∼ 8.12 dex. The baryonic mass versus effective oxygen yields, and the stellar, gas and baryonic mass versus SFE show higher dispersions and lower correlations. Since we use the dust mass as a tracer of gas mass, we derive the dust-to-gas ratio and the CO luminosity-to-molecular gas mass conversion factors, showing differences of 0.16 and 0.95 dex for the total and molecular gas surface density, respectively, in comparison to previously reported values. We use a self-regulated feedback model to conclude that stellar feedback plays an important role generating outflows in NGC 1569.

Alkali and alkaline earth metals catalytic steam gasification of ashless lignin: Influence of the catalyst type and loading amount

This work studies the effects of alkali and alkaline earth metallic species (AAEMs) (Na2CO3, K2CO3, and CaCO3), Na+ impregnation amount (2, 5, and 7 mmol) and sodium salts (NaHCO3, Na2SO4, and NaAlO2) on the gasification characteristics and product distribution of G-type lignin in a fixed-bed system for continuous gasification. The results showed that six catalysts all could improve lignin gasification performance by increasing total gas yields, syngas yields, H2/CO ratios, and carbon conversion rates. Na2CO3 had the strongest catalytic ability, followed by NaHCO3 and K2CO3, while CaCO3, Na2SO4 and NaAlO2 had poor catalytic abilities. Gaseous AAEMs, especially NaOH and KOH, could enhance tar cracking, volatiles reforming, coke gasification, the water-gas shift reaction, and methane steam reforming. The high melting points of CaO and NaAlO2 greatly reduced the catalytic capacities of CaCO3 and NaAlO2. AAEMs could combine with the carbon matrices to form carboxylate structures or phenol/aldehyde structures which might volatilize to catalyze homogeneous reactions. Moderately increasing Na+ impregnation amount to 5 mmol was beneficial to lignin gasification, but excessive impregnation reduced the gasification parameters. In addition, all six catalysts had effects on the tar composition, especially K2CO3 and NaAlO2, which could effectively catalyze tar cracking and reduce heavy compounds.

Clean conversion of pig manure via supercritical water gasification: Hydrogen-enriched syngas generation, mechanisms analysis, and environmental impacts

The energy potential of pig manure (PM) has garnered attention. Supercritical water gasification (SCWG) is proposed to convert PM to H2-enriched syngas without the drying process for wet materials. This paper studied the effect of diverse parameters on H2-enriched syngas production. The results revealed that higher temperatures and alkaline catalysts elevated total gas yield and H2 yield, with the addition of K2CO3 at 620 °C, 30 min, and 6 wt% feed concentration generating the highest total gas yield (36.55 mol/kg), H2 yield (18.89 mol/kg), and mole fraction (51.55%), accompanied by a high gasification efficiency (87.59%). Based on product characterization and thermodynamic analysis, reaction mechanisms were proposed to provide insight into enhancing syngas production, indicating that the suppression of polymerization reactions between cyclic compounds and the promotion of CH4, C2H6, and long-chain alkanes conversion were essential. Further, the environmental impact evaluation showed that heavy metals (Cu, Cr, As, and Zn) were concentrated in solid products by adsorption and passivation. The solid products exhibited negligible environmental hazards. This work showed that PM SCWG realized syngas production as well as heavy metals enrichment and stabilization, which could provide an alternative solution to the clean conversion of other types of organic wastes, especially with high heavy metals content, such as oily sludge and sewage sludge.

Catalytic pyrolysis of corncob with Ni/CaO dual functional catalysts for hydrogen-rich gas

BackgroundAs "carbon neutrality" has become an important topic in the world, biomass has become one of the important clean energy sources. Ni/CaO dual functional catalysts (DFCs) are promising for catalytic utilization of biomass. MethodsIn this paper, we optimized the reaction conditions and secondary metals (Cu (ⅠB), Ce (ⅢB), Mo (ⅥB)) based on Ni/CaO DFCs to improve the performance of catalytic H2 production from corncob. Significant findingsThe addition of Ce and Mo improved the H2 production of Ni/CaO DFCs, while Cu played an inhibitory role. Compared with Ce and Mo, Cu inhibited the strong adsorption of CO2 and H2O, leading to a decrease in H2 production. Under pyrolysis conditions, Mo had a stronger cracking ability towards oxygenated tars, achieving the highest total gas yield. Under steam gasification conditions, Ce produced oxygen vacancies and reactive oxygen species through redox reactions (Ce4+↔Ce3+), which promoted H2O dissociation adsorption and water-gas shift reaction (WGS). Therefore, under steam gasification conditions, Ce-Ni/CaO DFCs achieved the optimal H2 production (33.72 mmol/gbiomass, 81.25%) with good cycling performance. The work provided a new idea for the development of Ni/CaO DFCs and H2 production from biomass.

Experimental Investigation on Chemical Looping Co‐Gasification of Water Hyacinth and Solid Wastes

Chemical looping gasification (CLG) is a promising method to realize the resource utilization of solid waste. Chemical looping co‐gasification (CLCG) attracts much attention as it can fully utilize the synergistic effects between different types of fuels to improve the quality of gasification products. The CLCG characteristics of water hyacinth and different solid wastes, including straw, polypropylene, and sludge, are studied using lean iron ore as oxygen carriers (OCs). It is shown in the results that these solid wastes have synergistic effects on the CLG of water hyacinth to some extent. The addition of straw has a positive impact on gas production and H2/CO ratio, while the introduction of polypropylene and sludge focuses on improving gas production and H2/CO ratio, respectively. In addition, the optimal mixing ratios between water hyacinth and different solid waste are water hyacinth: straw = 50:50; water hyacinth: polypropylene 25:75; and water hyacinth: sludge = 75:25, respectively. The mixing of water hyacinth with polypropylene exhibits better gasification performance, in terms of the total gas yield of 1.27 Nm3 kg−1 and the H2/CO ratio of 1.76 at the mixing ratio of 25:75. This implies that the CLCG of biomass and polypropylene has better application prospect.

Effects of konjac glucomannan on physicochemical and rheological properties of whole egg liquid and in vitro fermentation of egg curd

The mixture of proteins, polysaccharides, and other nutrients not only safeguards the nutritional value of the food but also demonstrates superior performance compared to these nutrients when used individually. This study aimed to investigate the effects of konjac glucomannan (KGM) on the properties of whole egg liquid (WEL) and the in vitro fermentation of egg curd (made by the mixture of WEL/KGM). The results revealed that the foaming ability (FA) of the mixture decreased, while the foam stability (FS), emulsifying activity (EA), and emulsion stability (ES) of the mixture increased with increasing concentrations of KGM. The concentration of KGM had a significant effect on the sol-gel transition temperature of WEL. Compared to the fermentation broth of E group (without KGM), KGM decreased the pH from 6.65 to 6.16, free ammonia content from 87.53 μg/g to 72.21 μg/g, and sulfide concentration from 580 μg/L to 470 μg/L in the WEL/KGM mixture (EK group). Moreover, KGM slowed down the gas production of intestinal protein fermentation within 10 h, without affecting the final total gas yield. These findings suggest that adding KGM can be an effective strategy to modify the properties of WEL and improve the intestinal fermentation performance of protein-rich foods.

Enhanced oxygen activity of LaFeO3 oxygen carriers in biomass chemical looping gasification coupled with CO2/H2O splitting by fragmented flaky structure

Considering that the conventional modification of metal doping may bring excessive cost escalation and more pollution, for the sol–gel method, a more cost-effective and eco-friendly modification method was proposed to enhance the oxygen activity of LaFeO3 and its doped oxygen carriers (OCs). In this work, LaFeO3 OCs with fragmented flaky structure was prepared by modification of adjusting the sol to weak alkalinity with ammonia and adding the complexing agent ethylene glycol. Then, it was applied in Biomass chemical looping gasification (BCLG) coupled with CO2/H2O splitting to produce high-quality syngas and achieve cascade conversion of carbon in biomass, and its performance and reaction mechanism were investigated by fixed bed test. The results showed that the fragmented flaky structure endowed the LaFeO3 OCs with more robust oxygen activity, thus realizing efficient lattice oxygen migration which increased the gas yield of BCLG stage from 695.6 mL/g to 851.2 mL/g at 900 °C, and the carbon conversion and gasification efficiency reached 65.6% and 64.4%, respectively. Despite the predominant role of residual char in the gas generation of splitting stage, the reduced OCs still possesses exceptional CO2 and H2O splitting ability. Among them, CO2 splitting was mainly carried out by the activation of Fe0 and alkaline active sites from the reduced OCs, while H2O splitting depended more on the decomposition of H2O molecules by oxygen vacancies. Moreover, this OCs exhibited outstanding stability in 10 cycles, and the total gas yield in two stages was consistently maintained around 1030.1 mL/g and 1069.6 mL/g, respectively. This work found that the LaFeO3 OCs with fragmented flaky structure is a prospective material for chemical looping technology.

Influence of torrefaction as pretreatment on the fast pyrolysis of sugarcane trash

This study aims to perform a comprehensive analysis of the two-step pyrolysis process, including the three-phase products obtained from torrefaction followed by fast pyrolysis (FP), with particular attention to the redistribution of mass, elements and energy. Torrefaction pretreatment of sugarcane trash (ST) was carried out in a tube furnace at 220 °C, 260 °C and 300 °C for 60 min. Torrefaction results showed that the quality improvement of ST was in the increase in carbon content and the removal of low-calorific volatiles. Fast pyrolysis of raw and torrefied ST was carried out in a mechanically stirred fluidized bed reactor. The results showed that torrefaction pretreatment led to an increased biochar yield and a decreased bio-oil yield in the subsequent FP step. Nevertheless, the quality of obtained bio-oil was enhanced by the higher phenolic content and the lower water and acid contents. On the other hand, the total yield of liquid (including torrefaction liquid and FP bio-oil) of the two-step pyrolysis process decreased while the solid (biochar) yield increased and the total gas yield changed less, compared to the direct FP of raw ST. Furthermore, the elemental redistribution results revealed that most of the carbon (65.21–93.02 wt%) remained in ST after torrefaction, while considerable amounts of oxygen (26.14–69.58 wt%) and hydrogen (23.53–61.25 wt%) were transferred into the torrefaction liquid and non-condensable gases, including H2O, CO, and CO2, amongst others. Consequently, most of the feedstock energy (67.14–89.02 %) was transferred into FP products for the two-step pyrolysis process. In view of the redistribution properties and product quality (especially bio-oil), torrefaction prior to fast pyrolysis is recommended and 260 °C is regarded as a suitable temperature to balance product yield and quality. Overall, this study provides valuable data for a better understanding of the role of torrefaction pretreatment on biomass fast pyrolysis.

Oxygen uncoupling chemical looping gasification of biomass over heterogeneously doped La-Fe-O perovskite-type oxygen carriers

Biomass chemical looping gasification (BCLG) is a promising technology utilizes lattice oxygen for partial oxidation to produce high-value fuels. But in the field of BCLG, oxygen uncoupling chemical looping gasification (OU-CLG) is a novel concept that introduces molecular oxygen to optimize traditional gas-solid reactions. In this work, based on the most representative oxygen uncoupling elements successfully doped into La-Fe-O oxygen carriers, the results showed that the reaction performance not be positively correlated with the degree of oxygen uncoupling, only Co doping exhibited a better gasification performance than LaFeO3 did. Further, Co-LF differs from conventional LF in that it performs better in ex-situ gasification than in-situ gasification, with a total gas yield and carbon conversion efficiency of 1078.70 ml/g and 75.15% respectively. Further characterizations revealed that Co doping led to changes in the physical structure and reducibility. More importantly, enriched lattice oxygen and oxygen vacancies induced the formation of disordered reactive oxygen species in perovskite lattice, which promote the further oxygen uncoupling and the formation of oxygen uncoupling vacancies in ex-situ gasification. Moreover, doped but failure to promote the CLG might due to oxygen scarcity, impurity and elemental catalytic properties. Finally, a clear reaction mechanism regarding OU-CLG was proposed.