scholarly journals Insight into Relationship between Thermal Dissolution of Low-Rank Coals and Their Subsequent Oxidative Depolymerization

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 32
Author(s):  
Yugao Wang ◽  
Xiaochen Liu ◽  
Zhilei Wang ◽  
Chuan Dong ◽  
Jun Shen ◽  
...  
Keyword(s):  
Nitrogen Adsorption ◽  
Structural Features ◽  
Space Structure ◽  
Oxidation Products ◽  
Low Rank ◽  
Thermal Dissolution ◽  
Physico Chemical ◽  
Adsorption Desorption ◽  
The Relationship ◽  
Low Rank Coals

Oxidative depolymerization of low-rank coals is promising for obtaining benzene carboxylic acids (BCAs). However, it is hindered by the low yield of BCAs along with a large number of alphatic acids. Thermal dissolution could modify the physico-chemical structural features of low-rank coals, which is expected to improve the oxidation of LRCs. In this paper, lignite and subbituminous coal were firstly subjected to thermal dissolution with cyclohexane at 250 °C for 2 h. Then, the raw coal and the corresponding thermal insoluble portion (TIP) were oxidized by NaOCl under the same conditions. The residual yields of TIPs oxidation were both lower than those of raw coals oxidation, indicating that TIPs were more easily oxidized than the raw coals. The yield of BCAs obtained by TIPs oxidation was above 19% higher than that from the oxidation of raw coals. Meanwhile, the selectivity of BCAs was improved in the resulting oxidation products from TIPs compared with that from the raw coals. The relationship between BCAs generation and thermal dissolution of low rank coals was investigated by ultimate analysis, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption analysis. The results suggested that thermal dissolution could enrich aromatic portion in the remaining TIPs, resulting in an increasing of the yield and selectivity of BCAs. Simultaneously, thermal dissolution raised the specific surface area and expanded the looser space structure of TIPS, which were beneficial for the sufficient collision between aromatic structures and oxidant, facilitating the oxidative depolymerization of TIPs. This investigation would provide a novel route for promoting BCAs production by mild oxidative depolymerization of low-rank coals.

Preparation of Mesoporous Silica from Rice Husk Ash: Effect of Depolymerizing Agents on Physico-Chemical Properties

2010 ◽  
Vol 93-94 ◽  
pp. 664-667 ◽  
Author(s):  
Supakij Suttiruengwong ◽  
P. Puathawee ◽  
M. Chareonpanich
Keyword(s):  
Rice Husk ◽  
Rice Husk Ash ◽  
Chemical Properties ◽  
Nitrogen Adsorption ◽  
Mesoporous Silicas ◽  
Organic Residues ◽  
Hydrophobic Property ◽  
Carbon Chains ◽  
Physico Chemical ◽  
Adsorption Desorption

The aim of this work was to prepare mesoporous silicas derived from rice husk ash (RHA) using three different depolymerizing agents; glycerol, 1,3 propanediol and 1,4 butanediol. The reaction of RHA with different depolymerizing agents was carried out between 200-250°C for 2 hrs. The solution was then hydrolyzed with deionized water to obtain gels. After a few washing step, gels were oven-dried and calcined at 500 °C for 24 hrs. Prepared mesoporous silicas were then characterized using Nitrogen adsorption-desorption measurement, FTIR, TGA, SEM, XRD and XRF. The percent hydrophobicity was determined based on the amount of moisture absorbed using TGA. It was shown that RHA reacted with depolymerizing agents above 200°C to form gels, which, after hydrolysis and calcination, still maintained the mesoporous characteristics. The BET and SEM results indicated that the RHA reacted with 1,3 propanediol had highest pore volume (0.95 cm3/g) and specific surface area (129.30 m2/g) compared to RHA reacted with glycerol and 1,4 butanediol. The distribution of pores computed from BJH desorption branch was also more uniform. FTIR indicated that there was no significant change in the chemical structure of RHA reacted with different depolymerizing agents. The residual C-H bands were found in FTIR spectra for all prepared mesoporous silicas. TGA thermograms confirmed the existence of organic residues (below 2 %wt), which might result from incomplete elimination even after calcination. This was found to be an important factor affecting the hydrophobic property of the reacted RHA. The hydrophobicity of RHA may be tailored by controlling depolymerizing agents and organic residues. Depolymerizing agents with longer carbon chains also favoured the hydrophobic characteristics.

Structural features of low-rank coals

1990 ◽  
Vol 3 (2-3) ◽  
pp. 111-123 ◽  
Author(s):  
Harold H. Schobert
Keyword(s):  
Structural Features ◽  
Low Rank ◽  
Low Rank Coals

Physico-chemical properties of low-rank coals

2004 ◽  
Vol 148 (1) ◽  
pp. 38-42 ◽  
Author(s):  
V. Gómez-Serrano ◽  
M.C. Fernández-González ◽  
E.M. Cuerda-Correa ◽  
A. Macías-García ◽  
M.F. Alexandre-Franco ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Low Rank ◽  
Physico Chemical ◽  
Low Rank Coals

scholarly journals Pore size distributions and pore multifractal characteristics of medium and low-rank coals

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Bin Sun ◽  
Qing Yang ◽  
Jie Zhu ◽  
Tangsha Shao ◽  
Yuhang Yang ◽  
...  
Keyword(s):  
Pore Size ◽  
Pore Volume ◽  
Nitrogen Adsorption ◽  
Low Rank ◽  
Size Distributions ◽  
Confining Stress ◽  
Mercury Intrusion ◽  
Pore Size Distributions ◽  
Porosity And Permeability ◽  
Low Rank Coals

AbstractIt is of great significance to study the porosity and permeability properties of medium and low-rank coal. The porosity and permeability in confining stress experiments were used to simulate the porosity and permeability variations of coal samples under different depth conditions. The pore structure of Baoqing coal samples is greatly affected by the confining pressure, and the pores and micro cracks are more easily compressed. Based on the experimental data of mercury intrusion porosimetry (MIP) and nitrogen adsorption (NA), the pore size distributions (PSDs) of medium and low-rank coals were studied. High mercury intrusion pressure would lead to coal matrix compression. Therefore, the pore volume calculated by MIP data was corrected by NA data. The PSDs characteristics of Jixi (JX) coal and Baoqing (BQ) coal samples are obtained from the revised pore volume, and the dominant pores of medium and low-rank coals are obtained. The results show that JX coal has higher spatial heterogeneity, connectivity and pore autocorrelation. Micro fractures have an influence on the autocorrelation and heterogeneity of coal samples, especially for BQ coal samples.

scholarly journals Characterization of carbon fibrous material from platanus achenes as platinum catalysts support

10.30544/588 ◽  
2020 ◽  
Vol 26 (4) ◽  
pp. 375-383
Author(s):  
Branka V. Kaludjerovic ◽  
Vladislava M. Jovanovic ◽  
Sanja I Stevanovic ◽  
Zarko D. Bogdanov ◽  
Sanja S. Krstic ◽  
...  
Keyword(s):  
Carbon Materials ◽  
Platinum Catalysts ◽  
Nitrogen Adsorption ◽  
Carbon Support ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physico Chemical ◽  
Substrate Properties ◽  
Adsorption Desorption

Carbon materials with developed porosity are usually used as supports for platinum catalysts. Physico-chemical characteristics of the support influence the properties of platinum deposited and its catalytic activity. In our studies, we deposited platinum on carbon fibrous like materials obtained from platanus seeds - achenes. The precursor was chemically activated with different reagents: NaOH, pyrogallol, and H2O2, before the carbonization process. Platinum was deposited on all substrates to study the influence of the substrate properties on the activity of the catalyst. Carbon materials were characterized by nitrogen adsorption/desorption isotherms measurements, X-ray diffraction, and scanning electron microscopy. It was noticed that the adsorption characteristics of carbon support affected the structure of platinum deposits and thus their activity.

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