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Author

Ajay Kumar

Bio: Ajay Kumar is an academic researcher from Oklahoma State University–Stillwater. The author has contributed to research in topics: Biomass & Syngas. The author has an hindex of 26, co-authored 70 publications receiving 3311 citations. Previous affiliations of Ajay Kumar include University of Nebraska–Lincoln.
Topics: Biomass, Syngas, Tar, Wood gas generator, Char


Papers
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Journal ArticleDOI
21 Jul 2009-Energies
TL;DR: A review of thermochemical biomass gasification for producing biofuels, biopower and chemicals can be found in this paper, where the authors discuss the challenges with gasification are to understand the effects of operating conditions on gasification reactions for reliably predicting and optimizing the product compositions, and for obtaining maximal efficiencies.
Abstract: A review was conducted on the use of thermochemical biomass gasification for producing biofuels, biopower and chemicals. The upstream processes for gasification are similar to other biomass processing methods. However, challenges remain in the gasification and downstream processing for viable commercial applications. The challenges with gasification are to understand the effects of operating conditions on gasification reactions for reliably predicting and optimizing the product compositions, and for obtaining maximal efficiencies. Product gases can be converted to biofuels and chemicals such as Fischer-Tropsch fuels, green gasoline, hydrogen, dimethyl ether, ethanol, methanol, and higher alcohols. Processes and challenges for these conversions are also summarized.

740 citations

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TL;DR: In this article, the authors provide an overview of recent advances in several biochar utilizations including its use as catalyst, soil amendment, fuel cell, contaminant adsorbent, gas storage and activated carbon.
Abstract: Biomass thermochemical processes result in a common byproduct char. The char is also called biochar particularly when it is used as a soil amendment for soil health improvement. Effective utilization of biochar is critical for improving economic viability and environmental sustainability of biomass thermochemical technologies. Application of biochar for both agricultural and environmental benefits has been studied and reviewed extensively. However, there are limited reviews on other biochar applications, such as for catalysis and adsorption. This paper provides an overview of recent advances in several biochar utilizations including its use as catalyst, soil amendment, fuel cell, contaminant adsorbent, gas storage and activated carbon. Discussions on biochar production methods, properties and advanced characterization techniques are also provided. Biochar is a valuable resource, however, its effective utilization require further investigation of its structure and properties, and methods to modify those.

620 citations

Journal ArticleDOI
TL;DR: In this article, the performance of mathematical models to predict the product gas quality rely on characterization of feed materials and the reaction kinetics of their thermal degradation, and the authors determined selected physical and chemical properties of corn stover related to thermochemical conversion.
Abstract: Interest in generating energy from biomass has grown tremendously in recent years. Corn stover is an agricultural by-product, which is abundant in quantity. Gasification and pyrolysis are efficient methods of harnessing energy efficiently from corn stover. The performances of mathematical models to predict the product gas quality rely on characterization of feed materials and the reaction kinetics of their thermal degradation. The objective of this research was to determine selected physical and chemical properties of corn stover related to thermochemical conversion. Thermogravimetric analyses were performed at heating rates of 10, 30, and 50 °C min−1 in nitrogen (inert) and air (oxidizing) atmospheres. The parameters of the reaction kinetics were obtained and compared with other biomass. The weight losses of corn stover in both inert and oxidizing atmospheres were found to occur in three stages.

282 citations

Journal ArticleDOI
TL;DR: No significant difference was observed in the weight loss profiles of switchgrass, wheat straw and eastern redcedar even though their cellulose, hemicellulose and lignin contents were considerably different, but biomass composition did significantly affect gas evolution profiles.

260 citations

Journal ArticleDOI
TL;DR: Thermochemical biomass gasification was performed on a bench-scale fluidized-bed gasifier with steam and air as fluidizing and oxidizing agents and gasification temperature was found to be the most influential factor.

200 citations


Cited by
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Journal ArticleDOI
TL;DR: This critical review provides a survey illustrated by recent references of different strategies to achieve a sustainable conversion of biomass to bioproducts to examine critically the green character of conversion processes.
Abstract: This critical review provides a survey illustrated by recent references of different strategies to achieve a sustainable conversion of biomass to bioproducts. Because of the huge number of chemical products that can be potentially manufactured, a selection of starting materials and targeted chemicals has been done. Also, thermochemical conversion processes such as biomass pyrolysis or gasification as well as the synthesis of biofuels were not considered. The synthesis of chemicals by conversion of platform molecules obtained by depolymerisation and fermentation of biopolymers is presently the most widely envisioned approach. Successful catalytic conversion of these building blocks into intermediates, specialties and fine chemicals will be examined. However, the platform molecule value chain is in competition with well-optimised, cost-effective synthesis routes from fossil resources to produce chemicals that have already a market. The literature covering alternative value chains whereby biopolymers are converted in one or few steps to functional materials will be analysed. This approach which does not require the use of isolated, pure chemicals is well adapted to produce high tonnage products, such as paper additives, paints, resins, foams, surfactants, lubricants, and plasticisers. Another objective of the review was to examine critically the green character of conversion processes because using renewables as raw materials does not exempt from abiding by green chemistry principles (368 references).

2,077 citations

Journal ArticleDOI
TL;DR: A critical appraisal of different synthetic approaches to Cu and Cu-based nanoparticles and copper nanoparticles immobilized into or supported on various support materials (SiO2, magnetic support materials, etc.), along with their applications in catalysis.
Abstract: The applications of copper (Cu) and Cu-based nanoparticles, which are based on the earth-abundant and inexpensive copper metal, have generated a great deal of interest in recent years, especially in the field of catalysis. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. In addition, the design and development of novel support and/or multimetallic systems (e.g., alloys, etc.) has also made significant contributions to the field. In this comprehensive review, we report different synthetic approaches to Cu and Cu-based nanoparticles (metallic copper, copper oxides, and hybrid copper nanostructures) and copper nanoparticles immobilized into or supported on various support materials (SiO2, magnetic support materials, etc.), along with their applications i...

1,823 citations

Journal ArticleDOI
TL;DR: A broad review of the state-of-the-art biomass pyrolysis research can be found in this article, where three major components (cellulose, hemicellulose and lignin) are discussed in detail.

1,613 citations

Journal ArticleDOI
TL;DR: This review presents a comprehensive description of the current pathways for recycling of polymers, via both mechanical and chemical recycling, and discusses the main challenges and some potential remedies to these recycling strategies, thus providing an academic angle as well as an applied one.

1,352 citations

Journal ArticleDOI
TL;DR: This review summarizes the characteristics of biochar (e.g., surface area, porosity, pH, surface charge, functional groups, and mineral components) and main mechanisms governing sorption of As, Cr, Cd, Pb, and Hg by biochar and includes competitive sorption mechanisms of co-existing metals.

1,091 citations