Category Archives: LIQUID, GASEOUS AND SOLID BIOFUELS — CONVERSION TECHNIQUES

Advantages of gas fermentation

The production of first generation biofuels relies on food crops such as sugar beet, sugar cane, corn, wheat and cassava as substrates for bioethanol; and vegetable oils and animal fats for bio­diesel. Although years of intense R&D have made methods of bioethanol production (typically using the yeast Saccharomyces cerevisiae) technologically mature, there remain some serious questions regarding its sustainability. The […]

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Preface

Biomass is a renewable, unevenly geographically distributed resource that can be consid­ered sustainable and carbon-neutral if properly managed. It can be converted to high-quali­fied gaseous, liquid and solid biofuels with many techniques. This book focuses on the latest conversion techniques for the production of liquid and gaseous biofuels that should be of interest to the chemical scientists and technologists.

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Fermentation of lignocellulosic substrates2

4.1. Ethanol fermentation Fermentation of lignocellulose hydrolysates is more complicated compared to fermentation of 1st generation feedstock (sugar cane juice, molasses, grains) for several reasons: a) pentose sugars (predominantly xylose) are present along with hexoses (mainly glucose, mannose, galactose) in the hydrolysate, b) toxic compounds released during pretreatment can influ­ence metabolic activity of the fermentation strain, c) low concentrations of […]

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Feedstock and gasification

Due to the flexibility of the microbes to ferment syngas with diverse composition, virtually any carbonaceous materials can be used as feedstock for gasification. Non-food biomass that can be employed as feedstock for gasification includes agricultural wastes, dedicated energy crops, forest residues, and municipal organic wastes, or even glycerol and feathers [16—20]. Biomass is available on a renewable basis, either […]

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ABE (acetone-butanol-ethanol) fermentation

Different, so-called solventogenic species of the genus Clostridium, like Clostridium acetobu — tylicum, Clostridium beijerinckii or Clostridium saccharoperbutylacetonicum, can be used for 1- butanol production by ABE fermentation. The fermentation usually proceeds in two steps; at first butyric and acetic acids, along with hydrogen and carbon dioxide, are formed and then metabolic switching leads to the formation of solvents (mainly […]

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Fixed bed gasifier

Depending on the direction of the flows of carbonaceous fuel and oxidant (air or steam), fixed bed gasifier can be further categorized into updraft or downdraft reactor. In the up­draft (counter-current) version of the fixed bed gasifier, biomass enters from the top while gasifying agent from the bottom. The biomass moves down the reactor through zones of drying (100oC), pyrolysis […]

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Conversion of xylose under an acid catalyst

1.1. The chemical pathway Either in cyclic or aliphatic form, xylose then tends to dehydrate thus leading to the produc­tion of furfural whilst losing three molecules of water. Although this approach could explain the formation of furfural, it is not the sole options and many detailed reports have shown, by correlating the intermediaries with the actual structure, could be formed […]

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Fluidized bed reactor

In fluidized bed reactor, the carbonaceous fuel is mixed together with inert bed material (e. g. silica sand) by forcing fluidization medium (e. g. air and/or steam) through the reactor. The inert bed facilitates better heat exchange between the fuel materials, resulting in nearly isothermal operation conditions and high feedstock conversion efficiencies [18, 22]. The maximum operating temperature of the […]

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