Investigations and applications of renewable and sustainable energy have become central for addressing the issue of emissions of greenhouse gases from the use of fossil transportation fuels. ...Triglyceride-based liquid fuels have great potential as substitutes for petroleum and its derivatives. To date, the proven technologies for converting triglycerides into biofuels include transesterification, thermal cracking conversion, and hydrogenation. This paper presents an overview of recent research on these conversion technologies, employing homogeneous, heterogeneous, enzymatic, and photocatalytic catalysts. We focus on technical aspects critical to triglyceride conversion, including feedstock analysis, mechanism research, analysis of technological advantages and disadvantages, and catalyst development and selection. Biodiesel produced by the transesterification process must be blended with diesel before use due to its higher oxide content. The resultant “green diesel” has a broader range of applications, especially when its structure has been upgraded. Life cycle assessment (LCA) and greenhouse gas (GHG) emissions are reviewed to assess the renewability and sustainability of biofuels. We discuss the typical biodiesel production technologies with their development status, as well as the relevant policies and prospects for biofuels, mainly concerning biodiesel and aviation biofuel. It is hoped that our work will be of guiding significance for future biofuel research.
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•Overview of triglycerides biomass resources and their composition characteristics.•Overview of various possibilities conversion technologies for biofuel production are provided.•Overview of the composition characteristics of biodiesel and aviation biofuel and further upgraded for improving quality.•LCA and GHG emissions are reviewed to assess the renewability and sustainability of biofuels.
•Interpenetrating polymer network (IPN)-structured hydrogels were prepared.•Three different types of nanocellulose were incorporated into the hydrogels.•The hydrogels had an interconnected ...macro-porous structure.•The hydrogels could be utilized in multiple adsorption–desorption cycles.•The mechanical strength and adsorption capacity of hydrogels were enhanced by nanocellulose.
In this study, interpenetrating polymer network (IPN)-structured hydrogels were fabricated through the crosslinking of neutral polyacrylamide (PAM, the first flexible network) and the polyelectrolyte sodium alginate (SA, the second rigid network). Three types of nanocellulose, including cellulose nanocrystals (CNCs), bacterial cellulose fibers (BCs) and 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-oxidized cellulose nanofibers (TOCNs), were well-dispersed in the SA-PAM gel matrix. The hydrogels, obtained with a high water content (∼83%), exhibit a macroporous structure with a mean pore size of 60 ± 51 μm and high transparency. Comparative studies indicate that BCs are more effective for enhancing the hydrogels due to their higher aspect ratio, and the compressive strength of SA-PAM-BC hydrogel is 6.59 times higher than that of neat SA-PAM. Meanwhile, TOCNs are the best fillers for improving the adsorption capacity owing to the presence of a carboxyl group, and the adsorption capacity of SA-PAM-TOCN is more than 1.3-fold that in SA-PAM. Prepared hydrogels with high mechanical strength and adsorption capacity are advantageous for their applications in wastewater treatments.
A castor oil-derived diglycidyl ester plasticizer (C26-DGE) was prepared and incorporated into poly(vinyl chloride) (PVC) for the first time. The chemical structure of the product was characterized ...by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (
1
H-NMR), and carbon-13 nuclear magnetic resonance (
13
C-NMR). The plasticizing effects of C26-DGE as a primary or secondary plasticizer for the commercial plasticizer dioctyl phthalate (DOP) were studied. The mechanical properties, thermal stability, and migration stabilities of PVC films were investigated using dynamic mechanical analysis, thermogravimetric analysis (TGA), TGA-FTIR analysis, and PVC film surface analysis. Tensile, volatility, and extraction tests were also done. The castor oil-based plasticizer was found to endow the PVC matrix with enhanced compatibility and flexibility. With partially or completely substituted DOP, C26-DGE significantly increased the thermal stability of PVC blends. Furthermore, the volatility and extraction resistance of the novel plasticizers were generally superior to those of DOP. The interaction between the C26-DGE and PVC molecules and the thermal degradation process of PVC blends were also investigated.
Triglycerides obtained from animals and plants have attracted great attention from researchers for developing an environmental friendly and high-quality fuel, free of nitrogen and sulfur. In the ...present work, the production of biofuel by catalytic cracking of soybean oil over a basic catalyst in a continuous pyrolysis reactor at atmospheric pressure has been studied. Experiments were designed to study the effect of different types of catalysts on the yield and acid value of the diesel and gasoline fractions from the pyrolytic oil. It was found that basic catalyst gave a product with relatively low acid number. These pyrolytic oils were also further reacted with alcohol in order to decrease their acid value. After esterification, the physico-chemical properties of these biofuels were characterized, and compared with Chinese specifications for conventional diesel fuels. The results showed that esterification of pyrolytic oil from triglycerides represents an alternative technique for producing biofuels from soybean oils with characteristics similar to those of petroleum fuels.
Deoxygenation and molecular structural modification is a critical step before the practical application of triglycerides in aviation biofuels. For low quality waste triglycerides with high viscosity, ...traditional way of direct hydrogenation usually has problems such as catalyst deactivation and pipe clogging. Herein, we demonstrate a facile catalytic biorefinery process for high viscosity waste triglycerides for the production of aviation biofuels via a two-step catalytic conversion. Several typical plant oils (soybean and rubber seed oils) and waste triglycerides (waste cooking and acidified plant oils) are tested, which indicate that this approach is widely applicable, and can be used to produce aviation range products, linear hydrocarbons, at high yields (55%–60%), accompanied by a diesel range fuel of 15%–40% by adjusting the operation parameters. The aviation range hydrocarbons are further catalyzed by an Ni/ZSM-5 catalyst to achieve aromatization and hydrogenation in a one-pot synthesis. Three dominant components existing in aviation fuels, including chain hydrocarbons, aromatics and cycloalkanes, can be obtained, which present the same physical-chemical properties and components as petroleum-based aviation fuels. The proportion of the three main components can be modified by the amount of molecular sieve catalyst and the initial pressure of H2, in order to meet the requirements of variable-grade aviation fuels. Overall, a catalytic refining process of decarboxylation and molecular structural modification of low quality waste triglycerides for the entire/total substitution of petroleum aviation fuels from waste triglyceride is reported.
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•Decarboxylation of waste triglycerides to hydrocarbons was reported.•Liner hydrocarbon to cyclane was catalyzed by Ni/ZSM-5 bi-functional catalyst.•An reaction pathway of waste triglycerides to aviation fuel was reported.
The sluggish reaction kinetics in oxygen reduction reaction (ORR) is one of the bottlenecks in next generation energy conversion systems. The integrated design strategy based on simultaneously ...constructing active sites and forming porous carbon network will address this concern by facilitating charge exchange, mass transfer and electron transportation. In this article, a three-dimensional integrated air electrode (Co-N@ACS) containing Co-N sites and hierarchically porous carbon is fabricated via growth of Co-doped ZIF-8 in activated wood substrate and synchronous pyrolysis. The optimized integrated air electrodes exhibit ultrahigh ORR activity (
E
1/2
= 0.86 V). Co-N sites provide outstanding ORR activity, and hierarchically porous structures facilitate oxygen diffusion and electrolyte penetration. Aqueous zinc-air battery assembled with Co-N@ACS possesses open-circuit voltage of 1.46 V, peak power density of 155 mW·cm
−
2
and long-term stability of 540 cycles (180 h). Solid-state zinc-air battery assembled with Co-N@ACS shows open-circuit voltage up to 1.36 V and low charge-discharge voltage gap (0.8 V). This design strategy paves the way for the conversion of wood biomass to integrated air electrodes and catalytically active carbon for next generation energy storage and conversion devices.
Converting agriculture and forestry lignocellulosic residues into high value-added liquid fuels (ethanol, butanol, etc.), chemicals (levulinic acid, furfural, etc.), and materials (aerogel, bioresin, ...etc.)
a bio-refinery process is an important way to utilize biomass energy resources. However, because of the dense and complex supermolecular structure of lignocelluloses, it is difficult for enzymes and chemical reagents to efficiently depolymerize lignocelluloses. Strikingly, the compact structure of lignocelluloses could be effectively decomposed with a proper pretreatment technology, followed by efficient separation of cellulose, hemicellulose and lignin, which improves the conversion and utilization efficiency of lignocelluloses. Based on a review of traditional pretreatment methods, this study focuses on the discussion of pretreatment process with recyclable and non-toxic/low-toxic green solvents, such as polar aprotic solvents, ionic liquids, and deep eutectic solvents, and provides an outlook of the industrial application prospects of solvent pretreatment.
Hydrogels have been widely used in water purification. However, there is not much discussion and comparison about the effects of different nanofillers on the reinforcement and adsorption performances ...of hydrogels, which can be subjected to rapid water flow and possess strong adsorption ability. In this work, polyacrylamide (PAAM)-sodium alginate (SA) interpenetrating polymer network-structured hydrogels were prepared by in situ polymerization. PAAM formed the first flexible network and SA constructed the second rigid network. Three kinds of inorganic nanoparticles including carbon nanotubes (CNTs), nanoclays (NCs), and nanosilicas (NSs) were incorporated into a PAAM-SA matrix via hydrogen bond. The obtained hydrogels exhibited a macroporous structure with low density (≈1.4 g/cm
) and high water content (≈83%). Compared with neat PAAM-SA, the hydrogels with inorganic nanoparticles possessed excellent mechanical strengths and elasticities, and the compression strength of PAAM-SA-NS reached up to 1.3 MPa at ε = 60% by adding only 0.036 g NS in a 30 g polymer matrix. However, CNT was the best filler to improve the adsorption capacity owing to its multi-walled hollow nanostructure, and the adsorption capacity of PAAM-SA-CNT was 1.28 times higher than that of PAAM-SA. The prepared hydrogels can be potential candidates for use as absorbents to treat wastewater.
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