Carbon Resources Conversion最新文献

A degradative solvent extraction method for upgrading low-rank coal was performed at 200–350 °C for 90 min to obtain a substance dissolved in the solvent at room temperature (Soluble). Because the resulting mixture exhibited a high carbon content without ash, it could be readily used as a fuel. Furthermore, deep eutectic solvents (DESs) have attracted attention for improving the Soluble yield and decreasing the oxygen content in Soluble. DES is known to cleave oxygen-containing functional groups in biomass and is considered effective for deoxidizing low-rank coal. Herein, DES was prepared by mixing choline chloride, FeCl₃·6H₂O, and Adaro subbituminous coal (AD) and then added to 1-methylnaphthalene (1-MN) in a non-polar solvent, followed by degradative solvent extraction in the range of 200–350 °C. The effects of reaction temperature and added DES amount on the product yield and the composition were evaluated. As the reaction temperature and amount of DES added increased, the Soluble yield and carbon content increased. It was also found that the thermal decomposition temperature and oxygen content decreased with the increasing DES amounts. This decrease indicates that DES promotes the deoxygenation and decomposition of AD and increases the soluble yield of the fuel source.

Combustion of herb residues (HRs) for heat recovery is a good way for their utilization, but there exists such a problem as high concentration NOx emission in flue gas. The alcohol extracted herb residue (AEHR), one special type of HRs, was chosen as the object and was subjected to immediate combustion in a fluidized bed reactor to investigate the characteristics of its resulting NOx emission. The results showed that, most of the NOx in the flue gas was produced from the char nitrogen (CN); as the fuel water content increased, the NOx emission concentration exhibited a trend of first decreasing and then increasing; and a properly low combustion temperature inhibited the NOx emission upon the premise of ensuring full combustion. Air staging combustion was adopted to effectively control NOx: the NOx emission concentration in the flue gas was reduced to 296 mg·m⁻³ and the NOx emission reduction rate reached 46.51 % compared to conventional combustion. Co-combustion by blending wasted activated coke (WAC) into the AEHR helped both stabilize the combustion state and reduce further the NOx emission. When the blending ratio of WAC fell within a proper range of 20–30 %, the NOx emission concentration in the flue gas was as low as 231.4 mg·m⁻³. In addition to the dilution effect of the combustion flue gas of the blended WAC, the local reducing atmosphere caused by its incomplete combustion as well as its strong absorbability and catalytical effect was accountable for the further decrease of the NOx emission concentration.

The structural evolution and gasification reactivity of biochar prepared from the pyrolysis of wheat straw were investigated by in-situ Raman spectroscopy and thermogravimetric analysis. The Raman spectra consisted of a combination of four Lorentzian bands (D1, D2, D4, G) and one Gaussian band (D3) in the first-order region. The experimental results showed that the addition of catalysts or the presence of ash could improve the CO₂ gasification reactivity of biochar and result in a larger I_D1/I_G ratio and a lower I_G/I_ALL ratio, meaning that the carbon structure was less ordered, and there were also more active sites such as amorphous carbon and cross-linked structures; Ca-based catalysts and K-based catalysts changed the evolution of biochar structure in a different way in CO₂ atmosphere, the I_D3/I_D1 of Ca-based biochar was close to the value of non-catalyst biochar and decreased slowly, indicating that the Ca-based catalysts can stabilize the aromatic rings, while the I_G/I_ALL of K-based biochar decreases significantly and the I_D3/I_D1 increased significantly, indicating the increase of carbon structure defects and the cracking of large aromatic rings in bio-char into small ones; a scheme of K and Ca reaction with biochar in CO₂ gasification process was proposed.

Studies of carbon nanomaterials (CNM) synthesized from lignocellulosic biomass, and natural and technical lignins were carried out. For the first time, we suggested using stems of Sosnovsky hogweed, one of the most aggressive and poisonous invasive plant species, to produce CNM. The influence of the choice of raw materials and synthesis conditions on the sorption and surface-porous characteristics of the samples was evaluated. The main regularities of adsorption processes from aqueous media with a low concentration (0.625 μg/ml) of uranium were established. We found that strong retention of uranium characterizes carbonized biopolymers (CBP) samples, a significant amount of which (67–70%) is not desorbed either by water or aqueous solutions of CH₃COONH₄ and HCI (1 M). In addition, we found out that the carbon nanomaterials we synthesized can adsorb mycotoxin T-2. The obtained results indicated a high innovative potential of CNM.

Combustion of agricultural organic solid waste (AOSW) was an ideal solution for their resource utilization in view of their massive annual production and great potential for reduction of fossil fuel utilization. However, high alkali and alkaline earth metals (AAEMs) content in the feedstock can arose severe fouling and slagging issues and thus prohibiting its vast utilization. In this study, a semi-continuous water washing method was proposed to preliminarily remove AAEMs from agricultural organic solid waste and its effects on the combustion behaviors of washed solid product were investigated. Results showed that the combustion index S were improved to 2.63 × 10^-6, over 68 % of the total ashes were removed from the cotton stalk, and 96.3 %, 89.0 % and 74.7 % of K, Na and Mg were effectively removed, respectively. Moreover, the softening temperature of low temperature ash from the washed sample was as high as 1450 °C, 538 °C higher than the low temperature ash from the original sample; the base acid ratio and fouling index were improved from high slagging and fouling risk (1.7 and 90.8) of the original organic solid waste to low and medium risk (0.4 and 3.5), respectively. All these results signified the contributing effect of proposed semi-continuous water washing method on the combustion of agricultural organic solid waste. In a word, this study provided a promising method for fouling and slagging inhibition during the agricultural organic solid waste combustion.

It is known that simple adding of wood allows one to accelerate the ignition of powder mixtures compared to the situation when pure coal is used. This study focuses on testing the hypothesis about the effect of co-milling coal and wood on their co-firing: is the case of composite powdered fuels should ensure the maximum possible efficiency of heat and mass transfer? Firstly, we will show that co-milling of coal and wood leads not independent size reduction of two materials but gives composite powder – coal-covered wood. For the composite fuel further reduction of the ignition delay time of air suspension and reduction of the limit volume concentration required for flame propagation have demonstrated. Obtained synergy also manifests in thermogravimetry. Here we propose a simple method for analyzing the mass loss curves. For any coal-to-wood sawdust ratio, combustion of the composites and mixtures both can be viewed as a weighted sum of the curves of individual components. But only in the case of composites calculated sawdust content is higher than the actual one: the mass loss is redistributed towards the stage occurring at lower temperatures due to geometry of wood/coal contact.

In this study, the energy-efficient advanced procedure for the production of oil from plum seeds was proposed. The optimization of ultrasound-assisted extraction (UAE) of oil was carried out using the response surface methodology with the Box-Behnken design. The microwave pretreatment (MWP) of 460 W for 3 min was also applied to reduce the total extraction time. The extraction time (15 – 45 min), liquid-to-solid ratio (4 – 10 mL g⁻¹), and extraction temperature (40 – 60 °C) were defined as the factors. The oil yield was considered a response in this optimization study. The ultrasonic bath of 150 W and 40 kHz was used for the production of cavitation energy during the extraction. The optimal conditions were the extraction time of 42 min, the liquid-to-solid ratio of 10 mL g⁻¹, and the extraction temperature of 50 °C. Based on quality analysis, it was concluded that the oil obtained by MWP-UAE had adequate physico-chemical properties. The MWP-UAE was an efficient extraction technique in terms of extraction time and energy consumption.