scholarly journals Recent Perspectives in Biochar Production, Characterization and Applications

2021 ◽  
Author(s):  
Asfaw Gezae Daful ◽  
Meegalla R. Chandraratne ◽  
Marie Loridon
Keyword(s):  
Physicochemical Properties ◽  
Process Parameters ◽  
Pyrolysis Temperature ◽  
High Surface ◽  
Molar Ratios ◽  
High Affinity ◽  
Surface Areas ◽  
C And N ◽  
Proximate And Ultimate Analysis

This chapter presents the most promising features and applications of biochar along with their optimal pyrolysis conditions. Biochars have a range of physicochemical properties depending on the feedstock and pyrolysis conditions, which greatly affect their wide applications. The biochar production and its characteristics, including the effect of feedstocks and different process-parameters on the properties and yield of biochar are thoroughly examined. The higher pyrolysis-temperature can give higher carbon-contents, pH, and surface-areas of biochars while volatiles and molar-ratios of O/C, H/C and N/C decrease with pyrolysis-temperature. Higher carbon-content and neutral-pH biochars have high affinity for organic pollutants due to high surface areas, making them attractive for adsorption and catalysis purposes. Biochars with higher-pH are preferred for soil application to correct soil-acidity. Thus, the pyrolysis temperature should be selected as per the final application of the biochar. Characterization of biochars of different feedstocks and pyrolysis conditions is reviewed and presented along with their proximate and ultimate analysis.

Synthesis and Characterization of Aerogel-derived Cation-substituted Hexaaluminates

1996 ◽  
Vol 457 ◽  
Author(s):  
Lin-chiuan Yan ◽  
Levi T. Thompson
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Catalytic Combustion ◽  
High Surface ◽  
High Surface Area ◽  
Synthesis And Characterization ◽  
New Methods ◽  
Surface Areas ◽  
Different Characteristics

ABSTRACTNew methods have been developed for the synthesis of high surface area cation-substituted hexaaluminates. These materials were prepared by calcining high temperature (ethanol extraction) or low temperature (CO2 extraction) aerogels at temperatures up to 1600°C. Cation-substituted hexaaluminates have emerged as promising catalysts for use in high temperature catalytic combustion. In comparing unsubstituted and cation-substituted hexaaluminates, we found that the phase transformations were much cleaner for the cation-substituted materials. BaCO3 and BaAl2O4 were intermediates during transformation of the unsubstituted materials, while the cation-substituted materials transformed directly from an amorphous phase to crystalline hexaaluminate. Moreover, the presence of substitution cations caused the transformation to occur at lower temperatures. Mn seems to be a better substitution cation than Co since the Mn-substituted materials exhibited higher surface areas and better heat resistances than the Co-substituted materials. The low temperature aerogel-derived materials possessed quite different characteristics from the high temperature aerogel-derived materials. For example, phase transformation pathways were different.

scholarly journals Comparative characterization of biochars produced at three selected pyrolysis temperatures from common woody and herbaceous waste streams

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6784 ◽  
Author(s):  
Matthew Askeland ◽  
Bradley Clarke ◽  
Jorge Paz-Ferreiro
Keyword(s):  
Carbon Capture ◽  
Management Strategy ◽  
Pyrolysis Temperature ◽  
Land Application ◽  
Waste Streams ◽  
Fixed Carbon ◽  
Surface Areas ◽  
Polycyclic Aromatic ◽  
Shed Light

Biochar, the product of biomass pyrolysis, has been explored as a soil amendment and carbon capture vessel. Recent literature has aligned biochar as a novel sorbent for a host of environmental contaminants. Through the variation of pyrolysis conditions, biochars can be engineered to have qualities desirable in sorbents whilst maintaining their agronomic benefits. This study focuses on identifying the effects that feedstock type and process temperature have on biochar characteristics which may in turn shed light on their potential environmental applications. Using this approach, six biochars were created from two waste biomasses. The biochars exhibited wide ranges of pH (5.6–11.1), surface area (16.2–397.4 m2/g), electrical conductivity (19–2,826 µS/cm), fixed carbon (72–97%), heavy metal and polycyclic aromatic hydrocarbons (PAHs). Statistically significant trends (P < 0.05) in biochar characteristics dependent upon increasing pyrolysis temperature and feedstock type were identified. Arsenic (>13 mg/kg), chromium (>93 mg/kg), copper (>143 mg/kg) and PAH (>6 mg/kg) concentrations presented themselves as obstacles to land application in a small number of biochars with respects to International Biochar Initiative (IBI) guidelines. However, it was demonstrated that these could be eliminated through employing pyrolysis processes which encompass higher temperatures (>500 °C) and ensuring the use of contaminant-free feedstocks. The variation in surface areas, carbonized fractions and surface functional groups achieved suggest that using the correct feedstock and process, biochar could be produced in Victoria (Australia) from common organic waste streams to the ends of acting as a sorbent, soil enhancer, and a waste management strategy.

Preparation and characterization of highly active nanosized strontium-doped lanthanum cobaltate catalysts with high surface areas

2006 ◽  
Vol 51 (14) ◽  
pp. 1673-1681 ◽  
Author(s):  
Jianrong Niu ◽  
Wei Liu ◽  
Hongxing Dai ◽  
Hong He ◽  
Xuehong Zi ◽  
...  
Keyword(s):  
High Surface ◽  
Surface Areas ◽  
Highly Active

scholarly journals Catalytic Deactivation of HY Zeolites in the Dehydration of Glycerol to Acrolein

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 360
Author(s):  
Israel Pala-Rosas ◽  
José L. Contreras ◽  
José Salmones ◽  
Beatriz Zeifert ◽  
Ricardo López-Medina ◽  
...  
Keyword(s):  
Acid Sites ◽  
Molar Ratio ◽  
Lewis Acid Sites ◽  
Glycerol Conversion ◽  
Molar Ratios ◽  
Surface Areas ◽  
Large Mesopores ◽  
Hy Zeolites ◽  
Catalytic Deactivation

The study of the deactivation of HY zeolites in the dehydration reaction of glycerol to acrolein has represented a challenge for the design of new catalysts. HY zeolites with SiO2/Al2O3 molar ratios between 3.5 and 80 were studied. The solids were characterized by XRD, N2 physisorption, SEM-EDXS, Raman and UV-vis spectroscopies, infrared spectroscopy of pyridine (FTIR-Py) and catalytic activity tests from 250 °C to 325 °C. It was found that the total amount of acid sites per unit area of catalyst decreased as the SiO2/Al2O3 molar ratio increased from 3.5 to 80, resulting in the decrease in the initial glycerol conversion. The initial acrolein selectivity was promoted with the increase of the Brønsted/Lewis acid sites ratio at any reaction temperature. The deactivation tests showed that the catalyst lifetime depended on the pore structure, improving with the presence of large surface areas as evidenced by the deactivation rate constants. The characterization of the deactivated catalysts by XRD, N2 physisorption and thermogravimetric analysis indicated that the deposition of coke resulted in the total obstruction of micropores and the partial blockage of mesopores. Moreover, the presence of large mesopores and surface areas allowed the amount of coke deposited at the catalyst surface to be reduced.

scholarly journals Sulfidization of ferrihydrite in the presence of organic ligands

2021 ◽  
Author(s):  
Laurel K. ThomasArrigo ◽  
Sylvain Bouchet ◽  
Ralf Kaegi ◽  
Ruben Kretzschmar
Keyword(s):  
Trace Elements ◽  
High Surface ◽  
Organic Ligand ◽  
Organic Ligands ◽  
Molar Ratios ◽  
Iron Mineral ◽  
Surface Areas ◽  
Secondary Reactions ◽  
Mineral Components ◽  
The Impact

&lt;p&gt;In soils and sediments, short-range order (SRO) iron minerals constitute one of the most abundant and reactive mineral components. With high surface areas and points of zero charge near pH 7-8, SRO minerals like ferrihydrite (Fe&lt;sub&gt;10&lt;/sub&gt;O&lt;sub&gt;14&lt;/sub&gt;(OH)&lt;sub&gt;2&lt;/sub&gt;+mH&lt;sub&gt;2&lt;/sub&gt;O) are often linked to high adsorption of nutrients (C, N, P, S) and trace elements (e.g. As, Zn). However, under oxygen-limiting conditions, microbially derived sulfide (S(&amp;#8722;II)) may cause the rapid reductive dissolution of ferrihydrite and the release of associated nutrients and trace elements, thus influencing the biogeochemical cycling of trace elements and nutrients, particularly in redox dynamic environments.&lt;/p&gt;&lt;p&gt;Sulfidization of ferrihydrite occurs rapidly, whereby electron transfer between surface complexed sulfide and the ferrihydrite surface results in (partially) oxidized sulfur species and Fe(II). Depending on the S(-II):Fe molar ratios, secondary reactions then lead to mackinawite (FeS) or pyrite (FeS&lt;sub&gt;2&lt;/sub&gt;) precipitation. In nature, however, ferrihydrite is often found associated with natural organic matter (NOM). Because coprecipitation of ferrihydrite with NOM decreases particle size, alters the surface charge, and may block surface sorption sites, we speculated that kinetics and pathways of sulfidization of organic-associated ferrihydrite may differ from those of the pure mineral. Therefore, in this study, we followed iron mineral transformations and sulfur speciation during sulfidization of a pure ferrihydrite over one year and compared this to ferrihydrite coprecipitated with model organic ligands (polygalacturonic acid, galacturonic acid, and citric acid). Using a combination of solid- and aqueous phase Fe and S speciation techniques, we show that the impact of OM on ferrihydrite sulfidization kinetics and pathways varies with the chemical structure of the organic ligand, and that secondary reactions continue well past the initial rapid consumption of S(-II).&lt;/p&gt;

Synthesis and Characterization of Molecular Sieve SBA-15 and Catalysts Co/SBA-15 and Ru/Co/SBA-15

2014 ◽  
Vol 798-799 ◽  
pp. 100-105 ◽  
Author(s):  
Jocielys Jovelino Rodrigues ◽  
Liliane Andrade Lima ◽  
Gustavo Medeiros de Paula ◽  
Meiry Glaúcia Freire Rodrigues
Keyword(s):  
Molecular Sieve ◽  
High Surface ◽  
Nitrogen Adsorption ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Areas ◽  
Bet Method ◽  
Superficial Area

A series of mesoporous materials have been synthesized in an acid medium, with various structures, such as SBA-15. These materials have many properties which make them potential catalysts. Among these we highlight their high surface areas and pore walls relatively thick, resulting in a greater hydrothermal stability. This work aims at the synthesis and characterization of molecular sieve SBA-15 with molar composition: 1.0 TEOS: 0.017 P123: 5.7 HCl: 193 H2O and Co/SBA-15 and catalysts for the reaction of Ru/Co/SBA-15 Fischer Tropsch process. The materials were characterized by the techniques of X-ray diffraction (XRD), chemical analysis by X-ray spectrometry, energy dispersive (EDX) and Nitrogen adsorption (BET method). X-ray diffraction showed that the calcined cobalt catalyst did not modify the structure of SBA-15 and that Co was present under the form of Co3O4 in the catalyst. The addition of cobalt in the SBA-15 decreased the specific superficial area of the molecular sieve.

Synthesis, Characterization of Bimetallic V-Fe-SBA-15 and Its Catalytic Performance in the Hydroxylation of Phenol

2007 ◽  
Vol 7 (12) ◽  
pp. 4508-4514 ◽  
Author(s):  
Fei Gao ◽  
Yanhua Zhang ◽  
Chunling Wang ◽  
Cheng Wu ◽  
Yan Kong ◽  
...  
Keyword(s):  
Ph Value ◽  
High Surface ◽  
Mesoporous Structure ◽  
Catalytic Performance ◽  
Hydroxylation Of Phenol ◽  
Surface Areas ◽  
Hexagonal Arrangement ◽  
Ft Ir ◽  
Catalytic Performances

A series of V-Fe incorporated-SBA-15 has been synthesized by adjustment of the pH value of the gel mixtures and characterized by using XRD, N2-adsorption, ICP, FT-IR, Raman, and UV–vis techniques. Results indicated that all samples exhibited typical hexagonal arrangement of mesoporous structure with high surface areas and the heteroatoms were probably incorporated into the framework of SBA-15. Catalytic performances of the obtained materials were evaluated in the hydroxylation of phenol with H2O2, and the catalytic results revealed that the selectivity for catechol (CAT) and hydroquinone (HQ) could be controlled by adjusting the contents of V and Fe in the samples, and an appropriate nV/nFe mol ratio in SBA-15 could approach the optimal catalytic performance.

scholarly journals Adsorption of Paracetamol and Acetylsalicylic Acid onto Commercial Activated Carbons

2008 ◽  
Vol 26 (9) ◽  
pp. 721-734 ◽  
Author(s):  
Sabina Beninati ◽  
Domenica Semeraro ◽  
Marina Mastragostino
Keyword(s):  
Acetylsalicylic Acid ◽  
Activated Carbons ◽  
High Surface ◽  
High Surface Area ◽  
Adsorption Behaviour ◽  
Actual Surface ◽  
Ph Values ◽  
Surface Areas ◽  
Molecular Sizes

The adsorption of paracetamol (PAR) and acetylsalicylic acid (ASA) onto high-surface-area, commercial activated carbons was investigated at 26°C via adsorption isotherms at different pH values, including pH 1.5 to simulate conditions existing in the stomach. A wide-ranging characterization of the carbons, including analysis of their morphology and surface chemistry, was undertaken, with the actual surface areas of the carbons available for PAR and ASA adsorption being estimated by taking the molecular sizes of the drugs into account. This provided an understanding of the differences in the drug adsorption behaviour of the carbons.

Rheological Idiosyncrasies of Elastomer/Clay Nanocomposites

2008 ◽  
Vol 18 (5) ◽  
pp. 54894-1-54894-10 ◽  
Author(s):  
Zoran Susteric ◽  
Tomaz Kos
Keyword(s):  
High Surface ◽  
Clay Nanocomposites ◽  
Rheological Characterization ◽  
Melt Mixing ◽  
Mixing Processes ◽  
Rheological Analysis ◽  
Clay Particles ◽  
Surface Areas ◽  
Montmorillonite Clays

Abstract Rheological properties of elastomeric nanocomposites with organically modified Montmorillonite clays, as possible replacements or supplements to classical active fillers, such as carbon black or silica, have been intensively studied in recent years. Possessing large specific surface areas acquired through the melt-mixing processes of elastomeric intercalation and subsequent filler exfoliation, the clay particles have indeed proved to be highly eligible reinforcing and thermally stabilizing ingredients for application in elastomers. In fact, their performance has shown to be in many respects superior to that of classical fillers, particularly owing to some unusual, though beneficial, exhibited properties. Namely, apart from uncommonly high surface activity, manifested by creation of a host of van der Waals type secondary linkages with elastomer molecules, the main curiosity of clay filler is its dissipative action. Using dynamic mechanical functions under different deformational and temperature conditions, as means for rheological characterization of nanocomposites, the foregoing nano-scale traits are clearly reflected in substantial stiffness at low strains and, unexpectedly, dwindling energy loss with increasig filler content and/or decreasing temperature. Besides, rheological analysis of this kind, together with appropriate theoretical grounds, has enabled elucidation of peculiar conduct, as well as macroscopic insight into the very nature of secondary interactions in elastomers.

Characterization of Wet Impregnation Method for Catalytic Microcombustor by Using Platinum

2014 ◽  
Vol 699 ◽  
pp. 163-168
Author(s):  
Nazri Murat Muhamad ◽  
Azman Miskam Muhamad ◽  
Ahmad Mohd Azmier ◽  
Zainal Alimuddin Zainal Alauddin ◽  
Zulfikar Ishak Mohammad
Keyword(s):  
High Surface ◽  
Catalyst Support ◽  
Propargyl Alcohol ◽  
Support Surface ◽  
Impregnation Method ◽  
Surface Porosity ◽  
Wet Impregnation ◽  
Surface Areas ◽  
Wet Impregnation Method

The wet impregnation method for catalytic microcombustor was characterized by using platinum as a catalyst. The main purpose of this study is to increase the surface porosity of the catalyst support. A high surface porosity indicates that a high amount of catalyst was deposited within the surface areas. The performance of the catalytic microcombustor improves with increasing catalytic surface area. The stainless steel catalyst support was treated with sulfuric acid solution containing polyvinyl (3.89 wt%) and propargyl alcohol (1.48 wt%). Combustion test was performed using LPG-air to test the performance of the catalyst. The surface support treated with polyvinyl (PVA) showed a higher surface porosity and combustion blow-out limit compared with propargyl alcohol. The combustion mode changes from surface to submerged combustion after the catalyst was deposited in the support surface.

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