Carbon Resources Conversion最新文献

Regulation of gas–solid flow is crucial for optimizing the operation efficiency of dual-circulating fluidized beds that are considered to be the most appropriate type of chemical-looping reactors. Herein, a computational particle fluid dynamics method was employed to simulate the gas–solid flow in a 3-MW_th dual-circulating fluidized bed used for chemical-looping combustion and gasification. The influence of structural difference between units on particle residence time was determined. The multi-parameter control mechanism of pressure, particle circulation, and particle residence time in a whole-loop system was investigated. Results revealed that under stable particle circulation, the particle residence time in the fuel reactor is much longer than that in the air reactor. The axial forces on the particles are reduced upon increasing particle density and size, leading to particle accumulation in the dense-phase zone. When the particle properties are stable, increasing the fluidizing gas flow rates by the same proportion leads to identical pressure drops on the involved two loop seals, which cause symmetrical alterations in the particle circulation rate between the air and fuel reactors. The dual-circulating fluidized bed exhibits certain multi-condition adaptability, which is limited by the stock bin volume. Overall, this study is beneficial for effective and economical optimization of the operation of chemical-looping dual-circulating fluidized beds.

Carbon black (CB) is the most widely used reinforcing filler for rubber. Nowadays there are several concerns regarding this traditional petroleum-based filler: on one side its environmental footprint is enormous and its production process is no more sustainable and on the other side its price increases annually. For these reasons, sustainable alternative fillers are being studied. In the present research the main waste of the steel industry, namely the steel slag from electric arc furnace (EAF), is investigated as non-conventional filler for a nitrile butadiene rubber matrix (NBR). The slag has been characterized to ensure its safe reuse as filler according to the heavy metals leaching. The slag filled compounds have been characterized and compared to CB filled compounds, in terms of processability by rheometric parameters, mechanical properties, Payne effect, and physicochemical properties to investigate the filler-matrix interaction. From the obtained results, it was shown that EAF slag-filled NBRs are comparable to CB filled NBRs in terms of crosslink kinetics and, when compared at the same hardness level, are comparable in terms of viscosity, stiffness, and elongation at break, while when compared at the same filler volume fraction are similar in terms of compression set and stress relaxation.

Plastic waste is massively generated daily from households, mainly as packaging material, causing serious surrounding ecological problems. The development of plastic waste for higher value-added applications instead of landfilling and incineration has received consideration interest in bioenergy and material science research. Herein, a nanoporous carbon support of nickel phosphide catalyst for palm oil hydrotreating was developed from blended polystyrene waste and maize stover via the Co-hydrothermal carbonization (HTC) coupled with the KOH activation process. The Co-HTC parameters, such as temperature, reaction time, and PS percentage, were studied on the properties of co-hydrochar feedstocks for further activation using the Box behnken design. From the comprehensive characterization results, response surface methodology (RSM) results showed that the rising polystyrene proportion significantly exhibited the higher production yield and fixed carbon of co-hydrochar products, an essential characteristic for porous carbon manufacturing. After activation step, the final nanoporous carbon derived from the co-hydrochar (PMPC) exhibited the highest specific surface area of 1033.58 m²/g with total pore volume of 0.45 cm³/g. Moreover, the PCMC-supported nickel phosphide catalysts were successfully synthesized and tested for the catalytic hydrotreating of palm oil as alternative catalyst. The NiP-PMPC catalyst represents an impressive liquid hydrocarbon yield of 74.68 % with a high green diesel selectivity of 85.92 % at 100 % palm oil conversion. The findings of this study might help develop and utilize blended plastic waste and agricultural waste as an alternate catalytic support for various processes in biofuel and biochemical synthesis.

The present study numerically investigates the distinct combustion characteristics of a one-dimensional premixed laminar flame of gaseous ammonia under traditional, MILD, and high-temperature combustion regimes. Specifically, we examine the flames diluted by N₂ and H₂O, respectively, analyzing the flame structure, heat release rate, temperature, main species concentrations, and NO_x emissions. The fictitious gaseous diluents of FH₂O and FN₂ are applied to quantitatively distinguish physical and chemical effects. Results show that the chemical effect of dilution by N₂ is negligible while both physical and chemical effects by H₂O dilution significantly increase the flame thickness and hence reduce the heat release rate and temperature. Furthermore, both effects of H₂O dilution diminish as the burning regime transitions from MILD to traditional or high-temperature combustion. In particular, the H₂O dilution physically reduces the concentrations of the main species. On the other hand, the chemical effect raises the concentrations of H₂, OH, and NO in the traditional and high-temperature combustion, contrasting to that under the MILD regime. As for NO_x emissions, the H₂O dilution reduces NO emission in the MILD and high-temperature combustion but influences negligibly in traditional combustion. Additionally, the chemical effect of H₂O shows a contrasting influence on the NO emission under the MILD and high-temperature regimes. Comprehensive explanations are provided for the observed phenomena, shedding light on the intricate interplay of dilution and combustion.

Activated carbon (AC) possesses several versatile properties that make it a valuable material, including a higher surface area, high adsorption capacity, microporous structure, and increased surface reactivity. AC generation from pyrolysis of biomass can be economical and environmentally responsible using varied conversion technologies (thermochemical and biological processes). This review paper studied the effects of pre-treatment technology, activation process, and heating rates during the AC production stage. Also, the properties and abilities of AC generated from biomass were revealed. It also examined the catalytic performance of commercial compounds obtained from biomass and their combinations with other materials to improve bio-oil. Additionally, this paper deals with catalytic pyrolysis of biomass (phenol and hydrocarbon generation), adsorption of organic and pharmaceutical pollutants, and absorption of gases using AC. This comprehensive review offers a new perspective on creating biomass-derived activated carbon with superior characteristics for enhancing the absorption capacity of gases and organic and pharmaceutical pollutants.

The lignocellulose reinforced composites are commonly used sustainable materials with good mechanical and physical properties. Aiming to properly dispose and recover the potential value of discarded lignocellulose reinforced composites, the pyrolysis behaviour and kinetics of reed straw processing residual/polylactic acid (RSPR/PLA) composites, a typical 3D printing material, was investigated. Based on the TG-FTIR results, the synergistic effects between RSPR and PLA during the pyrolysis process were clarified. Compared with the FTIR spectra of PLA, the absorption peaks of CO and CO₂ disappear in the FTIR spectra of RSPR/PLA composite, which indicates RSPR provides additional free radicals for the free radical reaction of PLA, and further promoting the decomposition. The apparent activation energy of the RSPR/PLA composite pyrolysis was calculated by two iso-conversional methods including Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS). The average E_a of the RSPR/PLA composite (122.6 kJ mol⁻¹ (FWO) and 117.9 kJ mol⁻¹ (KAS)) was lower than that of solo pyrolysis of RSPR (138.5 kJ mol⁻¹ (FWO) and 135.4 kJ mol⁻¹ (KAS)) and the pure PLA (197.0 kJ mol⁻¹ (FWO) and 196.6 kJ mol⁻¹ (KAS)). The master plot method results suggested the pyrolysis of RSPR/PLA composite followed the one-dimensional (D1) diffusion model. This work provides an environmentally friendly strategy to effective thermo-chemical upgrading of the value of discarded lignocellulose reinforced composite material.

Despite lignin nanoparticles (LNPs) being extensively employed as assistant agents to improve the UV-blocking performance of sunscreens, there is a lack of information addressing how and to what extent the chemical and structural features of these particles relate to the improvements observed in the Sun Protection Factors (SPF) of the sunscreens. In this study, lignin oligomers were prepared by a solvothermal extraction process of five typical biomasses in a water–acetone co-solvent without noticeable degradation of the cellulose fraction. Afterward, LNPs were produced from the self-assembly of these lignin oligomers via the solvent-shifting methodology. When incorporated into the sunscreen, these had different morphologies, and exerted different UV-blocking capacities. The effects of the chemical structure and size distribution of the LNPs were systematically studied and compared to those of the original lignin oligomers. LNPs exhibited better UV-blocking ability than soluble lignin oligomers due to the more exposed chromophore on the surface. Besides, compact LNPs with conjugating CO and β-O-4 linkages, as well as the presence of the syringyl unit rich in the methoxyl group in the structures, were beneficial in boosting the UV resistance of the sunscreens. Even though smaller LNPs with higher surface area favored the UV shielding performance, LNPs with widely distributed sizes could further help decrease the UV transmittance. These findings provide an excellent basis for using lignin-derived materials as sunscreen additives and pave the way to developing new environmentally friendly materials for the cosmetic industry.

In this study, we introduce a straightforward and effective approach to produce P-doped hard carbon using coffee grounds as the precursor, with H₃PO₄ serving as the doping agent. By varying the concentrations of H₃PO₄ (1 M, 2 M, and 3 M), we aimed to determine the optimal doping level for maximizing the incorporation of phosphorus ions into the carbon framework. Our investigation revealed that using 2 M of H₃PO₄ as the dopant material for hard carbon led to promising electrochemical performance when employed as an anode material for sodium-ion batteries. The P-doped hard carbon, carbonized at 1300 °C, exhibited an impressive reversible capacity of 341 mAh g⁻¹ at a current density of 20 mA g⁻¹, with an initial Coulombic efficiency (ICE) of 83 %. This outstanding electrochemical performance of P-doped hard carbon can be attributed to its unique properties, including a porous agglomerated structure, a significant interlayer spacing, and the formation of C–P bonds.

The present study reports a successful attempt to produce single cell oil (SCO), heterogeneous base catalyst and yeast-based biodiesel from durian peel as a promising carbon feedstock by means of the waste-to-energy concept. For this purpose, first, durian peel (DP) was hydrolyzed by dilute sulfuric acid to obtain xylose-rich DP hydrolysate (XDPH) and post-hydrolysis DP solid residue (DPS). Candida viswanathii PSY8, a newly isolated oleaginous yeast, showed high SCO accumulation (5.1 ± 0.1 g/L) and SCO content (35.3 ± 0.13 %) on undetoxified XDPH medium. A novel heterogeneous base catalyst (DPS-K) prepared from DPS by wet impregnation technique with KOH, exhibited considerable catalytic activity to convert SCO-rich wet yeast of C. viswanathii PSY8 into yeast-based biodiesel (FAME) via direct transesterification with a maximum FAME yield of 94.3 % under optimal conditions (6 wt% catalyst, 10:1 methanol to wet yeast ratio, 75 °C, and 2 h). Moreover, most of the yeast-based biodiesel properties obtained from the FAME profiles were correlated well with the biodiesel standards limit of Thai, ASTM D6751 and EN 14214. Additionally, the energy output of FAME produced about 37.5 MJ/kg was estimated. Thus, this present finding demonstrated the favorable strategy for sustainable and eco-friendly production of new generation biodiesel.

The pyrolysis behaviors and temperature evolution history of lignocellulosic biomass (Beech, BH) were characterized using a novel pyrolysis model—C-DAEM. The simulation results were validated through corresponding experimental data. Based on the simulation results, two distinct peaks were observed in the temperature difference between the surface and center (TDSC) curve, namely the thermal disturbance peak (TDP) and the pyrolysis reaction peak (PRP). The presence of TDP and PRP was confirmed by examining the heat flux ratio between the pyrolysis rate and the temperature rise rate. Moreover, the results indicated that three factors, namely heating temperature, particle size, and pyrolysis rate, influenced the relative intensity between TDP and PRP. By changing the values of each impact factor, conditions where TDP owns the same height with PRP were obtained under different working conditions. These findings have led to the development of a dimensionless number, naming the pyrolysis-heating surface-center number (PH_SC number). This number could provide a comprehensive indication of the collective impact of the aforementioned factors when TDP and PRP exhibit equal peak heights.