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•WGSR is an important reaction for H2 production and CO2 capture.•A comprehensive review of the research progress in the WGSR is given.•State-of-the-art thermodynamic and kinetic ...characteristics of the WGSR are underlined.•WGSR behaviors in certain special environments are emphasized.•WGSR in membrane reactors for carbon capture and H2 production is addressed.
The water gas shift reaction is an important and commonly employed reaction in the industry. In the water gas shift reaction, hydrogen is produced from water or steam while carbon monoxide is converted into carbon dioxide. Over the years, on account of the progress in hydrogen energy and carbon capture and storage for developing alternative fuels and mitigating the atmospheric greenhouse effect, the water gas shift reaction has become a crucial route to simultaneously reach the requirements of hydrogen production and carbon dioxide enrichment, thereby enhancing CO2 capture. This article provides a comprehensive review of the research progress in the water gas shift reaction, with particular attention paid to the thermodynamic and kinetic characteristics. The performance of the water gas shift reaction highly depends on the adopted catalysts whose progress in recent years is extensively reviewed. The behaviors of the water gas shift reaction in special environments are also illustrated, several cases have the ability to proceed with water gas shift reaction without any catalyst. The utilization of several separation technologies on the water gas shift reaction such as carbon capture and storage and membrane reactors for purifying hydrogen and enriching carbon dioxide will be addressed as well. Reviewing past studies suggests that separating hydrogen and carbon dioxide in the product gas from the water gas shift reaction can not only increase efficiency but also enhance the usability for further application. The CO conversion is beyond the thermodynamic limitation after applying membrane for the water gas shift reaction.
•A state-of-the art review on recent research activities in microalgae pyrolysis is given.•Pyrolysis characteristics and kinetics of microalgae via TGA is reviewed.•Kinetic-free, single reaction and ...multiple parallel reaction and distributed activation energy models are introduced.•The kinetic models predicting the thermal degradation of microalgae are examined.•Pros and cons of microalgae pyrolysis using TGA are illustrated.
Pyrolysis is a promising route for biofuels production from microalgae at moderate temperatures (400–600°C) in an inert atmosphere. Depending on the operating conditions, pyrolysis can produce biochar and/or bio-oil. In practice, knowledge for thermal decomposition characteristics and kinetics of microalgae during pyrolysis is essential for pyrolyzer design and pyrolysis optimization. Recently, the pyrolysis kinetics of microalgae has become a crucial topic and received increasing interest from researchers. Thermogravimetric analysis (TGA) has been employed as a proven technique for studying microalgae pyrolysis in a kinetic control regime. In addition, a number of kinetic models have been applied to process the TGA data for kinetic evaluation and parameters estimation. This paper aims to provide a state-of-the art review on recent research activities in pyrolysis characteristics and kinetics of various microalgae. Common kinetic models predicting the thermal degradation of microalgae are examined and their pros and cons are illustrated.
Summary
Biofuel has emerged as an alternative source of energy to reduce the emissions of greenhouse gases in the atmosphere and combat global warming. Biofuels are classified into first, second, ...third and fourth generations. Each of the biofuel generations aims to meet the global energy demand while minimizing environmental impacts. Sustainability is defined as meeting the needs of the current generations without jeopardizing the needs of future generations. The aim of sustainability is to ensure continuous growth of the economy while protecting the environment and societal needs. Thus, this paper aims to evaluate the sustainability of these four generations of biofuels. The objectives are to compare the production of biofuel, the net greenhouse gases emissions, and energy efficiency. This study is important in providing information for the policymakers and researchers in the decision‐making for the future development of green energy. Each of the biofuel generations shows different benefits and drawbacks. From this study, we conclude that the first generation biofuel has the highest biofuel production and energy efficiency, but is less effective in meeting the goal of reducing the greenhouse gases emission. The third generation biofuel shows the lowest net greenhouse gases emissions, allowing the reduction of greenhouse gases in the atmosphere. However, the energy required for the processing of the third generation biofuel is higher and, this makes it less environmentally friendly as fossil fuels are used to generate electricity. The third and fourth generation feedstocks are the potential sustainable source for the future production of biofuel. However, more studies need to be done to find an alternative low cost for biofuel production while increasing energy efficiency.
• First generation biofuel has the highest biofuel yield and energy efficiency. However, the production of the biofuel opposed many sustainable development goals.
• Third and fourth generation biofuels show potential as a sustainable future green energy.
• Methods of lipid extraction of microalgae biofuel and environmental consequences of the fourth generation biofuel should be further explored.
Torrefaction is a mild pyrolysis, which has been explored for the pretreatment of biomass to increase the heating value and hydrophobicity. Due to its potential applications for making torrefied ...pellets, which can be used as a high quality feedstock in gasification for high quality syngas production and as a substitute for coal in thermal power plants and metallurgical processes, torrefaction and densification have attracted great interest in recent years from both academia and bioenergy industry. This paper provides a comprehensive review of research progresses in this area, drawing on major contributions from two major research groups of the authors on torrefaction and densification at Canada and Taiwan as well as literatures. It is revealed that torrefaction of various biomass species and their major components, lignin, cellulose and hemicelluloses have been extensively studied in thermogravimetric apparatus (TGA) under both inert (N2) and oxidative (O2, H2O) environments to elucidate the weight loss as a function of temperature, particle size and time. It was found that the higher heating value and saturated water uptake of torrefied biomass were a strong function of weight loss, which represents the degree of torrefaction. When torrefied sawdust is compressed into torrefied pellets, more mechanical energy is consumed and higher die temperature is required to make torrefied pellets of similar density and hardness as regular pellets. Simple economics analyses based on laboratory scale experimental data showed that because of the potential savings from pellets transport, handling and storage logistics, the overall cost for torrefied pellets can be lower than regular pellets in European market for both European and Canadian pellets. The gasification could be improved in terms of both energy efficiency and syngas quality because of the removal of oxygenated volatile compounds from torrefied biomass.
Zr‐based porphyrin metal–organic framework (MOF‐525) nanocrystals with a crystal size of about 140 nm are synthesized and incorporated into perovskite solar cells. The morphology and crystallinity of ...the perovskite thin film are enhanced since the micropores of MOF‐525 allow the crystallization of perovskite to occur inside; this observation results in a higher cell efficiency of the obtained MOF/perovskite solar cell.
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•Applications of biomass using TG, FTIR, and their combination are summarized.•Thermal degradation of lignocellulosic and no-lignocellulosic biomass is addressed.•The evolved gases ...including CO2, CO, H2, CH4 during the conversion are summarized.•TG-FTIR is a promising analytical technique for co-pyrolysis and co-gasification.
Effective methods of biomass characterization are needed for energy production due to the increase in biomass to bioenergy conversion capacity and the availability of various biomass sources. The utilization of biomass has been enhanced through thermochemical conversion techniques such as torrefaction, pyrolysis, and gasification. The biomass analytical techniques have been developed to decrease the time and energy required for biomass conversion performance. Thermogravimetric analyzer (TG) and Fourier transform infrared spectroscopic (FTIR) analytical techniques facing several limitations when applied individually. Thus, TG coupled with FTIR (TG-FTIR) was used to analyze the main parameters of biomass and improved the energy crop growing developments. In addition, TG-FTIR can determine the suitable ratio for two different biomass or coal blending during the co-pyrolysis and co-gasification to achieve the optimum synergetic interaction. In this review, thermochemical conversion processes such as torrefaction, pyrolysis, and gasification are presented. The analysis of the thermochemical conversion of biomass with the use of TG and FTIR individually are then discussed. Lastly, this review aims to discuss the applications of TG-FTIR techniques that have been applied to the analysis of evolved gas from the thermochemical processing of biomass to biofuels.
Enriched PD-L1 expression in cancer stem-like cells (CSCs) contributes to CSC immune evasion. However, the mechanisms underlying PD-L1 enrichment in CSCs remain unclear. Here, we demonstrate that ...epithelial-mesenchymal transition (EMT) enriches PD-L1 in CSCs by the EMT/β-catenin/STT3/PD-L1 signaling axis, in which EMT transcriptionally induces N-glycosyltransferase STT3 through β-catenin, and subsequent STT3-dependent PD-L1 N-glycosylation stabilizes and upregulates PD-L1. The axis is also utilized by the general cancer cell population, but it has much more profound effect on CSCs as EMT induces more STT3 in CSCs than in non-CSCs. We further identify a non-canonical mesenchymal-epithelial transition (MET) activity of etoposide, which suppresses the EMT/β-catenin/STT3/PD-L1 axis through TOP2B degradation-dependent nuclear β-catenin reduction, leading to PD-L1 downregulation of CSCs and non-CSCs and sensitization of cancer cells to anti-Tim-3 therapy. Together, our results link MET to PD-L1 stabilization through glycosylation regulation and reveal it as a potential strategy to enhance cancer immunotherapy efficacy.
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•Eight conversion routes for waste residues using microwave-assisted heating are reviewed.•Microwaves’ high energy use was offset by shorter duration and better product ...quality.•MW-assisted pyrolysis is the most studied route while other routes are still undermined.•Catalysis and co-processing of two wastes are the recent trends with several routes.•MW-assisted pyrolysis in a vacuum environment is one of the most recent advancements.
With drastic fossil fuel depletion and environmental deterioration concerns, a move towards a more sustainable bioenergy-based economy is essential. Lately, the application of microwave (MW) irradiation for waste processing has been attracting interest globally. MW-assisted heating possesses several advantages such as the provision of high microwave energy into dielectric materials with deeper penetration for internal heat generation, showing beneficial features in improving the heating rate and reducing the reaction time. Consequently, the most recent literature regarding the applications of MW-assisted heating for biomass pretreatment as well as biofuel and bioenergy production was reviewed and consolidated in this study. An impressive increase in the product yield and improvement of the product properties are reported, with the use of MW-assisted heating in several conversion routes to produce biofuels. Despite being a promising technology for biofuel production, some major fundamental data of MW-assisted heating have not been comprehensively identified. Therefore, the feasibility of this technology for large-scale implementation is still subpar. Understanding the interaction between the feedstock and the microwave electromagnetic field, and the optimization of several operational and mechanical parameters are the two main keystones that would propel the industrialization of MW heating in the near future. This provides key insights leading to increased feasibility and more advanced application of MW heating.
Methanol, a liquid hydrogen carrier, can produce high purity hydrogen when required. This review discusses and compares current mainstream production pathways of hydrogen from methanol. Recent ...research efforts in methanol steam reforming, partial oxidation, autothermal reforming, and methanol decomposition are addressed. Particular attention is paid to catalyst development and reactor technology. Copper-based catalysts are popular due to their high activity and selectivity towards CO2 over CO but are easily deactivated and have low stability. Attempts have been made using different metals like zinc, zirconia, ceria, chromium, and other transition metals. Catalysts with spinel structures can significantly improve activity and performance. Palladium-zinc alloy catalysts also have high selectivity towards H2 and CO2. For reactors, novel structures such as porous copper fiber sintered-felt are prefabricated and pre-coated before employment in microreactors. Monolith structures provide maximum surface area for catalyst coatings and lower pressure drops. Membrane reactors drive reactions forward to produce more H2. Swiss-roll reactors achieve heat recovery and energy saving in reactions. In summary, this comprehensive review of hydrogen production from methanol is conducive to the prospective development of a hydrogen-methanol economy.
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•Four main hydrogen production processes from methanol are reviewed.•Reaction mechanisms for methanol thermochemical conversion are discussed.•Recent progress in catalyst and reactor developments is reported.•A qualitative comparison between the processes is addressed.•Perspectives and challenges for hydrogen production from methanol are underlined.
In this study, environmentally-friendly nanocomposite hydrogels were fabricated. These hydrogels consisted of semi-interpenetrating networks of carboxymethyl cellulose (CMC) molecules grafted to ...polyacrylic acid (PAA), as an eco-friendly and non-toxic polymer with numerous carboxyl and hydroxyl functional groups, which were reinforced with different levels of graphene oxide particles (0.5, 1.5 or 3% wt). Field-emission electron scanning microscopy (FESEM) images indicated that the pore size of the nanocomposites decreased with increasing graphic oxide concentration. The presence of the graphic oxide increased the storage modulus and thermal stability of the nanocomposite hydrogels. The hydrogels had an adsorption capacity of 138 mg/g of a model cationic dye pollutant (methylene blue) after 250 min. Moreover, a reusability test showed that the adsorption capacity remained at around 90% after 9 cycles. Density functional theory (DFT) simulations suggested that the adsorption of methylene blue was mainly a result of π-π bonds, hydrogen bonds, and electrostatic interactions with graphene oxide. Our results indicated that the nanocomposite hydrogels fabricated in this study may be eco-friendly, stable, efficient, and reusable adsorbents for ionic pollutants in wastewater treatment.
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•Nanocomposite aerogels reinforced with graphene oxide were produced.•A porous 3D structure with SBET 42 mg/g was obtained for the aerogels.•An adsorption capacity of 138 mg/g was determined after 250 min•A high efficiency (90%) was detected after 9 cycles of adsorption-desorption.•Computer simulations showed π-π stacking was the main interaction between a model dye and graphene oxide.
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