Yield Of Gaseous Products Research Articles

Enhanced CH4 recovery from hydrate-bearing sand packs via CO2 replacement assisted thermal stimulation method

Natural gas exploitation from natural gas hydrate (NGH) reservoir by thermal stimulation combined with CO2 replacement is a promising method to enhance the natural gas recovery as well as sequestrate CO2 permanently. However, the operation scheme of thermal stimulation is crucial for the efficiency of both gas recovery and CO2 sequestration. In this study, a novel CO2–CH4 replacement assisted thermal stimulation method was proposed to enhance both CH4 recovery and CO2 sequestration simultaneously. Experiments were conducted in the CH4 hydrate unstable zone with pressure and temperature range from 1.97 to 3.22 MPa and 273.63–276.17 K, respectively. One step, continuous and stepwise thermal stimulation schemes with and without CO2 replacement were applied to evaluate the effect of different operation schemes on gas recovery and CO2 sequestration. The results indicated that the CO2–CH4 replacement process significantly increased the CH4 recovery percentage by 8.21%–34.79%. Overall, higher pressure and temperature were able to provide higher CO2–CH4 exchange driving force, which leaded to higher CH4 recovery ratio and CO2 sequestration efficiency. Among three thermal stimulation schemes, the stepwise thermal stimulation showed the best CH4 recovery of 62.60% and CO2 sequestration efficiency of 71.23% on average. The maximum CH4 recovery percentage of 69.51% and CO2 sequestration efficiency of 88.29% were obtained at 3.21 MPa and 276.13 K with stepwise thermal stimulation. The mechanism of this recovery enhancement can be concluded to that CH4 hydrate decomposition rate was enhanced by repeatedly imposed heat fluctuation in stepwise thermal stimulation and eventually the CH4–CO2 replacement process in hydrate was promoted. By comparison with published data, the CH4 recovery efficiency in this work increased by 19.2% on average. We expected that the proposed combination method could be applied in the late stage of NGH reservoir exploitation to obtain an enhanced CH4 gas production yield with sequestration of CO2 simultaneously.

Low-temperature biomass tar model reforming over perovskite materials with DBD plasma: Role of surface oxygen mobility

Tar conversion or removal is one of the most troublesome issues limiting biomass or solid waste gasification technology's industrialization. A cost-effective and energy-efficient way of conversion of tar is indispensably dreamed. In this work, an efficient conversion of biomass tar was demonstrated in an integrated catalytic-DBD plasma process to address this. The role of lattice oxygen species for biomass tar model reforming reaction over various perovskite structured La8Ce2-M5Ti5Ox (M = Fe, Co, Ni and Cu) materials was evaluated in an integrated catalytic-DBD plasma process. The tar reforming activity was discussed by considering the production of gaseous products such as H2, CH4 and CO, which are the main components to achieve high calorific values for the product. Among all the perovskite materials, Co-containing La8Ce2-Co5Ti5Ox gave a superior catalytic performance in oxidative toluene reforming reactions. At 250 °C and 90 W discharge power, La8Ce2-Co5Ti5Ox catalyst showed 98% of toluene conversion and the product gas yield of 60 vol% and 27 vol% for CO and H2 gases, respectively. The energy content of the syngas is enhanced from 36 kJ/h for plasma only reaction to 62 kJ/h and 68 kJ/h for LC-Fe5Ti5Ox and LC-Co5Ti5Ox catalysts, respectively. Besides, LC-Fe5Ti5Ox catalyst showed enhanced H2 yields with the addition of small amounts of H2O by maintaining similar toluene conversion. The catalytic performances of the perovskite materials were correlated with the oxygen mobility nature of the materials. XRD analysis revealed that the stable perovskite structure is present for all the materials before and after the exposure to plasma energy. O2-TPD and XPS results revealed that the O species present in La8Ce2-Co5Ti5Ox materials are more mobile than other materials. Finally, the high surface oxygen mobility nature and stable perovskite structure were the possible reasons for the best performance of LC-Fe5Ti5Ox and La8Ce2-Co5Ti5Ox catalysts over other catalysts.

Process Analysis of Main Organic Compounds Dissolved in Aqueous Phase by Hydrothermal Processing of Açaí (Euterpe oleraceae, Mart.) Seeds: Influence of Process Temperature, Biomass-to-Water Ratio, and Production Scales

This work aims to systematically investigate the influence of process temperature, biomass-to-water ratio, and production scales (laboratory and pilot) on the chemical composition of aqueous and gaseous phases and mass production of chemicals by hydrothermal processing of Açaí (Euterpe oleraceae, Mart.) seeds. The hydrothermal carbonization was carried out at 175, 200, 225, and 250 °C at 2 °C/min and a biomass-to-water ratio of 1:10; at 250 °C at 2 °C/min and biomass-to-water ratios of 1:10, 1:15, and 1:20 in technical scale; and at 200, 225, and 250 °C at 2 °C/min and a biomass-to-water ratio of 1:10 in laboratory scale. The elemental composition (C, H, N, S) in the solid phase was determined to compute the HHV. The chemical composition of the aqueous phase was determined by GC and HPLC and the volumetric composition of the gaseous phase using an infrared gas analyzer. For the experiments in the pilot test scale with a constant biomass-to-water ratio of 1:10, the yields of solid, liquid, and gaseous phases varied between 53.39 and 37.01% (wt.), 46.61 and 59.19% (wt.), and 0.00 and 3.80% (wt.), respectively. The yield of solids shows a smooth exponential decay with temperature, while that of liquid and gaseous phases showed a smooth growth. By varying the biomass-to-water ratios, the yields of solid, liquid, and gaseous reaction products varied between 53.39 and 32.09% (wt.), 46.61 and 67.28% (wt.), and 0.00 and 0.634% (wt.), respectively. The yield of solids decreased exponentially with increasing water-to-biomass ratio, and that of the liquid phase increased in a sigmoid fashion. For a constant biomass-to-water ratio, the concentrations of furfural and HMF decreased drastically with increasing temperature, reaching a minimum at 250 °C, while that of phenols increased. In addition, the concentrations of CH3COOH and total carboxylic acids increased, reaching a maximum concentration at 250 °C. For constant process temperature, the concentrations of aromatics varied smoothly with temperature. The concentrations of furfural, HMF, and catechol decreased with temperature, while that of phenols increased. The concentrations of CH3COOH and total carboxylic acids decreased exponentially with temperature. Finally, for the experiments with varying water-to-biomass ratios, the productions of chemicals (furfural, HMF, phenols, cathecol, and acetic acid) in the aqueous phase is highly dependent on the biomass-to-water ratio. For the experiments at the laboratory scale with a constant biomass-to-water ratio of 1:10, the yields of solids ranged between 55.9 and 51.1% (wt.), showing not only a linear decay with temperature but also a lower degradation grade. The chemical composition of main organic compounds (furfural, HMF, phenols, catechol, and acetic acid) dissolved in the aqueous phase in laboratory-scale study showed the same behavior as those obtained in the pilot-scale study.

Steam co-gasification of Japanese cedarwood and its commercial biochar for hydrogen-rich gas production

In this study, steam gasification and co-gasification of Japanese cedarwood and its commercial biochar were performed in a lab-scale fixed-bed reactor to investigate the feasibility for producing H2-rich syngas. Ultimate analysis, proximate analysis, Brunauer-Emmett-Teller (BET) surface area analysis, and scanning electron microscopy (SEM) were conducted to understand the changes caused by the carbonization process. The effects of gasification temperature and steam flow rate on gas production yield from the steam gasification of the individual samples were investigated at first, which showed larger gas production yield and less tar yield for the steam gasification of the commercial biochar than that of raw cedarwood, indicating that the commercial biochar obtained from the carbonization process was more beneficial for the gasification. The co-gasification of raw Japanese cedarwood and its commercial biochar with different mixing ratios was conducted at different reaction temperatures. The synergistic effect was obviously observed. Especially, the commercial biochar with the highly porous structure and high content of alkali and alkaline earth metal (AAEM) species might provide the catalytic effect on cracking and reforming of tar derived from the raw cedarwood, resulting in a larger H2 yield. However, the catalytic effect and gasification reactivity of biochar would decrease by increasing the amount of raw-cedarwood in the blends due to the coke deposition on the surface of biochar.

Conversion of syngas to triptane-rich liquid hydrocarbons via oxygenates

The triptane-rich liquid hydrocarbons are produced from syngas via oxygenates in two stages: in the first stage the oxygenates (methanol and dimethyl ether) are formed from CO + H2 over the Cu-Zn-Al-catalyst; in the second stage the oxygenates are converted to triptane-rich liquid hydrocarbons over the combined Mg-HZSM-5/Pd-La-HY catalyst. Over the Mg-HZSM-5, light olefins are formed in high yield, while the formation of triptane occurs over the Pd-La-HY, which is active in the isomerization of aliphatic hydrocarbons and in the alkylation of light iso-paraffins with light olefins. The increased water content in the reaction zone was found to lead to an increase in the yield of gaseous products. Water acts as an inhibitor of chain growth and methylation reactions and leads to the accumulation of methanol in the condensate. For efficient and stable (more than 72 h) operation of Mg-HZSM-5/Pd-La-HY, the concentration of water in the feedstock should not exceed 10 wt. %.

Effect of slow pyrolysis conditions on biocarbon yield and properties: Characterization of the volatiles

Slow pyrolysis of spruce and birch was performed at various heating programs and conditions in a horizontal quartz tube reactor heated by an electric furnace. The effects of feedstock and carbonization conditions on the yield of biocarbon, liquid and gaseous products were studied. The thermal properties, volatile matter (VM) content and the evolution profiles of volatiles from the biocarbons were characterized by thermogravimetry/mass spectrometry. The composition of volatiles was analyzed in detail by pyrolysis–gas chromatography/mass spectrometry. Increased char yield was observed when staged pyrolysis program, low purging flow rate or covered sample holder were applied. Spruce produced more charcoal than birch due to the higher lignin content of softwood. The amount and the evolution profiles of the main gaseous products were similar from spruce and birch biocarbons prepared under the same conditions. The relative amount of aromatic and polyaromatic compounds in VM drastically decreased with increasing carbonization temperature.

Effect of potassium on catalytic characteristics of ZSM-5 zeolite in fast pyrolysis of biomass-based furan

The effect of potassium in biomass on the catalytic activity of ZSM-5 zeolite in the fast pyrolysis of biomass was investigated using 2-methylfuran (2-MF) as the typical model compound. The mechanism of action of potassium was explored in detail, along with the physicochemical properties of ZSM-5, including crystallinity, pore structure, and surface acidity. The physicochemical properties of ZSM-5 deteriorated to varying degrees after being tainted with different potassium sources (KOH, K2CO3, KAc, and KCl). Compared with neutral KCl and strong alkali KOH, K2CO3, and KAc, with weaker alkalinity but larger crystal structure, exerted a larger influence on ZSM-5. Changes in ZSM-5 tainted with K2CO3 were the greatest, and crystallinity, surface area, acidity, and the corresponding yields of valuable aromatic hydrocarbons and gas products, all declined significantly, compared with raw ZSM-5. When the amount of K(CO32−) on ZSM-5 was less than 0.5 wt%, only minor (<10 %) changes were observed in crystallinity and surface area, but total acidity decreased by over 30 percent. The conversion of 2-MF was increased using ZSM-5 tainted with less than 0.5 wt% K(CO32-) and less liquid oxygenated compounds and more CO2 were produced. Appropriate total acidity, adjusted by a tiny amount of K2CO3, could promote deoxygenation to CO2. However, the decarbonylation reaction was inhibited, causing a negative effect on monocyclic aromatic hydrocarbons, which was attributed to the large-scale loss of both acidity and physical structure of ZSM-5 caused by more than 1.0 wt% K(CO32-).

Catalytic gasification of coal in a decoupled dual loop gasification system over alkali-feldspar

The catalytic gasification of Yuyang coal for the production of hydrogen-rich syngas has been performed in a novel decoupled dual loop gasification system using alkali-feldspar as an in-situ catalytic bed material. This experimental setup is comprised of a fluidized bed gasifier (FBG), a moving bed reformer (MBR), a riser combustor (RC) and a particle grading cyclone (PGC). By the PGC, two loops, i.e. a gasification loop with quartz sand as circulating bed material between the FBG and the RC and a reforming loop with alkali-feldspar as circulating bed material between the MBR and the RC, are formed. The effects of process parameters such as reformer temperature (700–850 °C), steam/coal ratio (S/C) (0.6–1.5) and air equivalence ratio (ER) (0.15–0.30) on the composition of product gas, lower heating value (LHV), tar content, yield of product gas, the carbon and water conversions and the cold gas efficiency were investigated. At the reformer temperature of 850 °C, the lowest tar content 5.8 g/Nm3 and the maximum yield of product gas 1.0 Nm3/kg daf were obtained. The addition of steam increased the H2 yield. The maximum hydrogen concentration of 65.1 vol% in product gas was attained at the S/C ratio of 1.5. Oxygen as a part of gasification agent led to the rise of CO2 concentration from 24.3 to 46.3 vol% and the reduction of H2 concentration from 54.4 to 33.0 vol% with the increase of ER from 0.15 to 0.30.

Hydrothermal gasification of Scenedesmus obliquus and its derivatives: a thermodynamic study using Aspen Plus

AbstractThis study presents the simulation of hydrothermal gasification (HTG) of Scenedesmus obliquus microalgae and their derivatives using Aspen Plus V11. The effect of operating parameters such as temperature, pressure, and biomass concentration on the yield and composition of gaseous products using whole algae, lipid, and lipid extracted algae (LEA) as feedstocks was examined. The results showed that reaction pressure exhibited minimal impact whereas temperature, biomass concentration, and feedstock composition had significant effects on the composition of gaseous products. It was also found that a low temperature (400 °C) and biomass concentration of 40 wt% favored the production of methane‐rich gas. In contrast, high temperature (700 °C) and low biomass concentration (10 wt%) favored hydrogen‐rich gas production in all the three feedstocks considered. The highest mole fraction achieved for CH4 was 53.45, 61.70, and 52.20 mol%, which corresponded to a CH4 yield of 31.14, 56.90, and 30.15 mmol g−1 for whole algae, lipid, and LEA respectively. For H2 rich gas production, the highest mole fractions achieved were 55.77, 52.29, and 55.34 mol%, which correspond to H2 yields of 75.44, 105.51, and 73.49 mmol g−1 for whole algae, lipids, and LEA, respectively. The ranking order for the yield and lower heating value of the product gas from the HTG process is lipid &gt; whole algae &gt; LEA. This study has shown that hydrogen‐rich and methane‐rich gas can be produced from the hydrothermal gasification of microalgae as a function of the reaction conditions and feedstock composition. © 2021 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

The Effect of MoS2 Active Site Dispersion on Suppression of Polycondensation Reactions during Heavy Oil Hydroconversion

In this work, the composition, structural and morphological features, and particle size of the active phase of the catalyst (MoS2), synthesized in-situ during the heavy oil hydroconversion performed in continuous flow reactor on lab-scale pilot flow unit at T = 450 °C, P = 6.0–9.0 MPa, V = 1.0 h−1, H2/feed = 1000 nL/L, catalyst concentration C (Mo) = 0.01–0.08%wt have been studied. It has been shown that MoS2 formed during hydroconversion is represented by nanosized particles stabilized by polycondensation products as a result of strong adsorption and aggregation with the components of the hydroconversion reaction medium. The influence of morphological characteristics of catalyst nanoparticles on the feed conversion, the yield of gaseous and liquid products, and the quality of distillate fractions, as well as the yield of polycondensation products, have been studied. It has been established that an increase in MoS2 active site dispersion, both due to a decreased plate length and lower stacking numbers in MoS2 cluster, enhances hydroconversion effectivity, particularly, in suppressing polycondensation reactions.

Study of chemical looping co-gasification of lignite and rice husk with Cu-Ni oxygen carrier

Abstract Coal is the dominant composition of fossil fuel but, with the accompanying gaseous products, causes environmental pollution. Here, we report a methodology to improve C conversion in co-gasification. The steam gasification and chemical looping gasification (CLG) of lignite and rice husk with oxygen uncoupling over 5% NiO/CuO oxygen carrier were conducted by non-isothermal kinetics method in a fixed-bed reactor. The gasification results showed that the yields of gas products in CLG of lignite or rice husk are higher than that in steam gasification. The yields of gases in chemical looping co-gasification (CLCG) are higher than that in steam co-gasification. In the co-gasification, the complementation of reactivity between fuels facilitated the C conversion rate, so the yields in co-gasification were higher than in individual gasification. The C conversion in CLCG of lignite and rice husk is 14.51% higher than that in steam co-gasification.

Optimization of hydrothermal gasification process through machine learning approach: Experimental conditions, product yield and pollution

This study involves the development of a machine learning algorithm based Tunable Decision Support System (TDSS) and Tunable Recommendation System (TRS) for optimizing the process conditions and product yield values of hydrothermal gasification (HTG) of biomass. More than 500 datasets were collected from various studies and laboratory experiments performed. Initially, these data were correlated and the coefficients were determined using the Pearson matrix. Based on the statistical consolidation, weighted rank aggregates were formed and trends among these aggregates were derived and stored in the cloud repository. Test datasets were analysed using the predicted trends and iterations were continued until the required response values were derived. The precision of the predicted results was compared with actual results and %Accuracy values showed more than 94% accuracy in predicting HTG process conditions for a given set of biomass input characteristics. The correlation studies revealed that %Hydrogen, %Carbon, %Volatile matter, %Moisture & %Oxygen present in biomass are highly responsible for the yield and quality of product gas by influencing HTG conditions like Temperature (T in °C), Pressure (P in MPa), Catalyst Loading (Cat. Load in wt. %), Solvent to Biomass ratio (S/B) and Time (t in min). As a part of the optimization study, the production of polluting gases like CO2 and CO (collectively accounted for pollution index) were also modeled. The TRS function available in this framework suggests suitable alternatives when the input conditions do not suit to yield an expected response outcome. Multiple data and parameter-driven processes like HTG can be optimized efficiently using this system.

Lignin pyrolysis under NH3 atmosphere for 4-vinylphenol product: An experimental and theoretical study

Conversion of lignin into the valuable chemicals is critical for the high-valued utilization of lignin. In this study, a simple method to produce 4-vinylphenol through lignin pyrolysis under NH3 atmosphere was proposed. Lignin pyrolysis behavior was investigated at 400–800 °C by a fixed-bed reactor. Formation mechanism of 4-vinylphenol was explored with density functional theory calculations. Results showed that NH3 promoted the cracking of biochar to increase the yield of bio-oil and gaseous product. H2 was the main component, and its yield increased significantly at higher temperature (reaching 190 mL/g), while the yield of CH4 and CO2 decreased largely. Introduction of NH3 promoted formation of phenols without methoxy through removing –O-CH3 branches of phenols with methoxy. The 4-vinylphenol yield increased about five times, and reached 4.89 wt% with the relative content of 23.43% at 600 °C. For the formation mechanism of 4-vinylphenol, in initial pyrolysis stage, hydrogen abstraction of amino can promote the Cβ-O bond cleavage. In the branched chain crack stage, NH3 provides more H free radicals and can also promote dehydration and decarbonylation reaction to form 2-methoxy-4-vinylphenol, and reduce the high energy barrier of demethoxylation significantly in the final stage. Furthermore, the possible reaction pathways of producing 4-vinylphenol from lignin pyrolysis under NH3 atmosphere were proposed.

Modeling of industrial-scale sorption enhanced gasification process: One-dimensional simulations for the operation of coupled reactor system

Sorption enhanced gasification (SEG) is a promising technology for producing gas derived from renewable feedstock to be used in biofuel synthesis processes. As a response to the growing need for renewable fuels, an SEG reactor design was developed for industrial-scale dimethyl ether (DME) production. A 100MWth scale SEG reactor concept for wood pellets as a feedstock was created by a model-based approach. Thus, a 1D modeling tool for the coupled circulating fluidized beds was developed. The model was used to investigate the dual fluidized bed system’s operation in the gasifier temperature range of 730–790°C. In this range, the optimal producer gas composition without external hydrogen for the downstream DME synthesis was achieved at gasifier temperature 730°C: 63 %vol,dbH2, 11 %vol,dbCO, 13 %vol,dbCO2. The model prediction was successfully compared against experimental data and modeling results from the literature. The developed 1D model enables the investigation of the composition and yield of the producer gas with different operating parameters, such as the part-load operation. This advanced capability can be used to develop new control strategies for the SEG system and investigate the impact of various operating parameters on the producer gas composition and yield.

Thermal-catalytic destruction of polyolephin polymers in presence of LnVO3 and LnVO4

This paper describes non-catalytic and catalytic pyrolysis of plastic waste materials. Four types of waste plastics were used in study: high density polyethylene (PE), low density polypropylene (PP), polyethylene terephthalate (PET). Plastic waste was decomposed into three fractions under pyrolysis conditions: gas, liquid and solid residual. The use of vanadates MeVO4 and vanadites MeVO3 of REM (Me=La, Gd, Lu) as catalysts let to change the yield of the gas fraction and change the composition of the gaseous pyrolysis products. Catalytic decomposition increased the amount of the gaseous products by 15–20 %, reduced the condensate, and changed their composition with regard to the non-catalytic process at the same pyrolysis temperature. The total number of reaction products was determined in each fraction. The quantitative analysis of the composition of the gas fraction was performed by gas-liquid chromatography. The study of non-catalytic pyrolysis of plastics and thermogravimetric analysis let to determine the most favorable temperature conditions for the implementation of the catalytic pyrolysis. The catalytic pyrolysis of plastics was carried out in order to obtain the maximum yield of valuable gaseous products. The synthesized vanadites and vanadates of REM were used as catalysts. When using catalysts based on lanthanum and gadolinium compounds, a regular change in the amount of gaseous substances was observed without significant changes in their composition. The use of lutetium vanadate and lutetium vanadite demonstrated a phenomenal result that is associated with the cardinal change of structure of degradation products of PET. The syngas was obtained instead of acetaldehyde. This result is related to the structure of the used catalyst.

Hydrogen-rich gas production from steam co-gasification of banana peel with agricultural residues and woody biomass

Steam co-gasification of banana peel with other biomass, i.e., Japanese cedar wood, rice husk and their mixture, was carried out for the hydrogen-rich gas production in a fixed-bed reactor. For the co-gasification process, the banana peels were physically mixed with rice husk, Japanese cedarwood and their mixture respectively by different mixing weight ratios. The effects of reaction temperature and the addition amount of banana peel on the gas production yield were investigated by comparing the experimental data with the calculated ones based on the individual biomass gasification at the same condition. It was found that the banana peel with a high content of alkali and alkaline earth metal (AAEM) species exhibited not only high gasification reactivity but also a significant enhancing catalytic effect on the co-gasification process at the low temperature, especially with the biomass containing no silica species. The high content of silica species in the rice husk had a negative effect on the gasification reactivity of banana peel during the co-gasification since it could hinder the release of AAEM from the biomass and/or lead to the possible formation of inactive alkaline silicates. However, the combination of these three samples with the suitable weight ratio could improve the gasification performance at the low temperature due to the synergetic effect provided by high contents of potassium and calcium from banana peel and cedarwood respectively. Moreover, the addition of calcined seashells as the CaO source could further improve the gas production yield, especially the hydrogen gas yield at a relatively low gasification temperature of 750 ℃.

Study of the Synergetic Effect of Co-Pyrolysis of Lignite and High-Density Polyethylene Aiming to Improve Utilization of Low-Rank Coal.

The mutual impact of low-quality lignite and high-density polyethylene (HDPE) during open system pyrolysis was investigated, aiming to improve utilization of lignite with simultaneous treatment of HDPE waste. Pyrolysis of lignite, HDPE, and their mixture (mass ratio, 1:1) was performed at temperatures 400, 450, 500, 550, and 600 °C. Initial substrates and pyrolysis products were characterized by thermogravimetric analysis (TGA), gas chromatography–mass spectrometry (GC–MS), specific carbon isotope analysis of individual hydrocarbons (δ13C), Rock-Eval pyrolysis, and elemental analysis. The positive synergetic effect during co-pyrolysis of lignite/HDPE mixture was observed at temperatures ≥450 °C, with the greatest being at 500 °C. The highest yield of liquid co-pyrolysis products with a similar composition to that of crude oils is also noticed at 500 °C. The yields of liquid and gaseous products and quality of pyrolytic products obtained by co-pyrolysis of lignite/HDPE mixture are notably improved compared with pyrolysis of lignite alone. On the other hand, data obtained from pyrolysis of HDPE alone indicate that it cannot be concurrent to well-developed catalytic thermal processes for polymer recycling. However, concerning the huge amount of produced HDPE, at least part of this plastic material can be reused for advanced thermal treatment of lignite, particularly in countries where this low-rank coal represents the main source of energy.

Production of phenolic compounds in catalytic pyrolysis of bagasse lignin in the presence of Ca0.5Pr0.5FeO3

Herein, sodium dodecylbenzene sulfonate (SDBS) was used as a template to control the synthesis of Ca0.5Pr0.5FeO3. Its microstructure, composition, and morphology were detected via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The properties of catalyzing bagasse lignin (BL) pyrolysis were determined by thermogravimetric analysis (TG) test and evaluation of a fixed bed alumina microreactor. The results show that the sample Ca0.5Pr0.5FeO3 regulated by SDBS has a cubic crystal phase, and the addition of SDBS does not cause phase transition. Moreover, when the SDBS concentration is 0.10 mol/L, the particle size is 200–500 nm and the specific surface area is 11.26 m2/g. The yields of gas, liquid, and solid products in the BL catalytic pyrolysis are 39.58 wt%, 26.76 wt% and 32.36 wt%, respectively. The contents of CO2 and CO decrease from 54.07% and 4.98% to 45.29% and 3.23%, respectively. The liquid products are mainly guaiacol, syringol, and phenol, and the total selectivity of phenols is 83.67%, accompanied by a small amount of non-aromatic oxygen-containing compounds (five-membered ring (furan) or ester). Compared with the BL pyrolysis and Ca0.5Pr0.5FeO3 catalytic pyrolysis products, the selectivity of guaiacol compounds increases by 43.26%, while those of syringol compounds and phenylketones decrease by 30.08% and 3.39%, respectively. The selectivity of 2,6-dimethoxyphenol is 28.37%. After five catalytic pyrolysis-regeneration cycles, the characteristic peaks of the catalyst do not change significantly and the particles are uniform, suggesting that the catalyst has good crystal phase stability and regeneration stability.

Plasmonic Au–Pd Bimetallic Nanocatalysts for Hot-Carrier-Enhanced Photocatalytic and Electrochemical Ethanol Oxidation

Gold–palladium (Au–Pd) bimetallic nanostructures with engineered plasmon-enhanced activity sustainably drive energy-intensive chemical reactions at low temperatures with solar simulated light. A series of alloy and core–shell Au–Pd nanoparticles (NPs) were prepared to synergistically couple plasmonic (Au) and catalytic (Pd) metals to tailor their optical and catalytic properties. Metal-based catalysts supporting a localized surface plasmon resonance (SPR) can enhance energy-intensive chemical reactions via augmented carrier generation/separation and photothermal conversion. Titania-supported Au–Pd bimetallic (i) alloys and (ii) core–shell NPs initiated the ethanol (EtOH) oxidation reaction under solar-simulated irradiation, with emphasis toward driving carbon–carbon (C–C) bond cleavage at low temperatures. Plasmon-assisted complete oxidation of EtOH to CO2, as well as intermediary acetaldehyde, was examined by monitoring the yield of gaseous products from suspended particle photocatalysis. Photocatalytic, electrochemical, and photoelectrochemical (PEC) results are correlated with Au–Pd composition and homogeneity to maintain SPR-induced charge separation and mitigate the carbon monoxide poisoning effects on Pd. Photogenerated holes drive the photo-oxidation of EtOH primarily on the Au-Pd bimetallic nanocatalysts and photothermal effects improve intermediate desorption from the catalyst surface, providing a method to selectively cleave C–C bonds.

Performance of dynamic anaerobic membrane bioreactor (DAnMBR) with phase separation in treating high strength food processing wastewater

Food processing wastewater (FPW) contains high levels of oil and grease (O&G), especially from factories that produce fast food such as nuggets, sausages, and burger patties from beef, poultry, and fish. Therefore, the feasibility of replacing conventional membranes for the treatment of FPW with low-cost dynamic membranes (DM) as an alternative was investigated in this study. An anaerobic DM bioreactor (DAnMBR) was operated for 90 days to evaluate the treatment performance using real FPW under different organic loading rates (OLR) of 3.5, 5.0, 6.5, and 7.0 g COD (chemical oxygen demand)/Lday. Once the reactor had reached a steady-state of 90% COD removal, the feed to the reactor was supplemented incrementally with FPW from 10% to 90% as COD to allow the methanogenic bacteria to acclimate any potential inhibitory effects from its recalcitrant content. The bioreactor presented a stable performance at OLR 5.0 g COD/Lday with 97.5% removal of COD and reached 20 mg/L total suspended solids (TSS) discharge. A significant correlation between COD fractions removed via acidogenesis and methanogenesis with different OLR was found, indicating that the increase in treatment performance is beneficial to the methanogenic archaea activity. The methane gas production yield achieved a maximum of 0.40 L methane/g CODadded at OLR 3.5 and 5.0 g COD/Lday. The average permeate flux in these studies is around 60 L/m2h. The DM fouled after 57 days (at flux 27.16 L/m2h immediate drop to 2.16 L/m2h) when operated at 3.5 g COD/Lday. After it fouled, the membrane underwent physical cleaning, backwashed in-situ for 5 min, and reused again without any chemical cleaning. The improved filtration resistance is contributed by the occurrence of DM fouling induced by the soluble microbial products (SMP) and extracellular polymeric substances (EPS) release as well as the increased protein/carbohydrate (P/C) ratio in the mixed liquor.