There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

1.0. Introduction 4044 2.0. Biomass Chemistry and Growth Rates 4047 2.1. Lignocellulose and Starch-Based Plants 4047 2.2. Triglyceride-Producing Plants 4049 2.3. Algae 4050 2.4. Terpenes and Rubber-Producing Plants 4052 3.0. Biomass Gasification 4052 3.1. Gasification Chemistry 4052 3.2. Gasification Reactors 4054 3.3. Supercritical Gasification 4054 3.4. Solar Gasification 4055 3.5. Gas Conditioning 4055 4.0. Syn-Gas Utilization 4056 4.1. Hydrogen Production by Water−Gas Shift Reaction 4056

/pdf/synthesis-of-transportation-fuels-from-biomass-chemistry-3sckhzoqoz.pdf

Synthesis of transportation fuels from biomass: chemistry, catalysts, and engineering.

Sustainable production of renewable energy is being hotly debated globally since it is increasingly understood that first generation biofuels, primarily produced from food crops and mostly oil seeds are limited in their ability to achieve targets for biofuel production, climate change mitigation and economic growth. These concerns have increased the interest in developing second generation biofuels produced from non-food feedstocks such as microalgae, which potentially offer greatest opportunities in the longer term. This paper reviews the current status of microalgae use for biodiesel production, including their cultivation, harvesting, and processing. The microalgae species most used for biodiesel production are presented and their main advantages described in comparison with other available biodiesel feedstocks. The various aspects associated with the design of microalgae production units are described, giving an overview of the current state of development of algae cultivation systems (photo-bioreactors and open ponds). Other potential applications and products from microalgae are also presented such as for biological sequestration of CO 2 , wastewater treatment, in human health, as food additive, and for aquaculture.

/pdf/microalgae-for-biodiesel-production-and-other-applications-a-54vmwufrsu.pdf

Microalgae for biodiesel production and other applications: A review

Biomass is an important feedstock for the renewable production of fuels, chemicals, and energy. As of 2005, over 3% of the total energy consumption in the United States was supplied by biomass, and it recently surpassed hydroelectric energy as the largest domestic source of renewable energy. Similarly, the European Union received 66.1% of its renewable energy from biomass, which thus surpassed the total combined contribution from hydropower, wind power, geothermal energy, and solar power. In addition to energy, the production of chemicals from biomass is also essential; indeed, the only renewable source of liquid transportation fuels is currently obtained from biomass.

The Catalytic Valorization of Lignin for the Production of Renewable Chemicals

Biofuels produced from various lignocellulosic materials, such as wood, agricultural, or forest residues, have the potential to be a valuable substitute for, or complement to, gasoline. Many physicochemical structural and compositional factors hinder the hydrolysis of cellulose present in biomass to sugars and other organic compounds that can later be converted to fuels. The goal of pretreatment is to make the cellulose accessible to hydrolysis for conversion to fuels. Various pretreatment techniques change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates. During the past few years a large number of pretreatment methods have been developed, including alkali treatment, ammonia explosion, and others. Many methods have been shown to result in high sugar yields, above 90% of the theoretical yield for lignocellulosic biomasses such as woods, grasses, corn, and so on. In this review, we discuss the various pretreatment process methods and the recent literature that...

http://ucce.ucdavis.edu/files/datastore/234-1388.pdf

Methods for Pretreatment of Lignocellulosic Biomass for Efficient Hydrolysis and Biofuel Production

PROBLEM TO BE SOLVED: To provide a method for hydrolyzing a polysaccharide substance, by which saccharides such as glucose can selectively and efficiently be produced from a polysaccharide substance such as cellulose in semi-critical or supercritical water as a solvent. SOLUTION: This method for hydrolyzing the polysaccharide substance, comprising bringing the polysaccharide substance such as cellulose into contact with the semi-critical or supercritical water, is characterized by making a quinone compound coexistent in the reaction system. Thereby, the polysaccharide substance can selectively and quickly be hydrolyzed. COPYRIGHT: (C)2005,JPO&NCIPI

Method for hydrolyzing polysaccharide substance

Various types of crystalline cellulose consisting of group I (cell I, IIII, IVI) and group II (cell II, IIIII, IVII) prepared from cotton linter were adjusted for their degree of polymerization (DP) as starting materials. These celluloses were then treated by semi-flow hot-compressed water (HCW) at 230–270 °C/10 MPa/2–15 min to study their decomposition behaviors. The treatments performed resulted in residues of celluloses and water-soluble (WS) portions. Consequently, the crystallinity of the residues was found to remain the same, but the DP was reduced as the temperature increased. Additionally, X-ray diffractometry and Fourier transform-infrared analyses demonstrated that crystallographic changes occurred for residues of cell IIII, IVI and IIIII. Despite these changes, the overall results of the residues showed that group I has higher resistance to decomposing than group II. As for the WS portions, the yields of the hydrolyzed and degraded products were higher in group II than group I, indicating that group II is less resistant to decomposition by HCW treatment. Results for both the residues and WS portions are in agreement with each other, showing that the degree of difficulty of decomposition was higher in group I than group II. Therefore, the decomposition behaviors of the celluloses are due to differences in the crystalline forms.

/pdf/decomposition-behaviors-of-various-crystalline-celluloses-as-13l8efeeh9.pdf

Decomposition behaviors of various crystalline celluloses as treated by semi-flow hot-compressed water

Supercritical fluid technology has been applied to convert lignocellulosics into bioenergy and chemicals. As a result, it was found that lignocellulosics could be separated into carbohydrate-derived and lignin-derived products by supercritical water treatment. A detailed study of these products revealed that useful products such as oligosaccharides and related substances could be achieved for subsequent ethanol fermentation. It was further found that the prolonged treatment could produce various organic acids for subsequent methanogen to produce methane and methanol. Based on these lines of research achievements, supercritical water technologies were proved to be powerful to produce useful bioproducts from lignocellulosics.

Useful Products from Lignocellulosics by Supercritical Water Technologies

The molecular arrangement of wood cell wall is described in relation to the physical and mechanical properties of wood. The chemical composition of wood is also summarized to illustrate the heterogeneity in distribution of cell wall constituents to use wood plup fibers judiciously as natural raw materials for cellulose acetate production.

2. The raw materials of CA 2.1 Wood as natural raw materials for cellulose acetate production

Gas-phase conversions of volatile intermediates from cellulose (AvicelPH-101)
 were studied using a two-stage experimental setup and compared with those of
 levoglucosan (1,6-anhydro-b-D-glucopyranose). Under N2or 7% O2/N2flow, vapors
 produced from the pyrolysis zone (500°C) degraded in the secondary reaction
 zone at 400,500, 600 or 900°C (residence time:0.8-1.4 s). The 69.3% (C-based)
 of levoglucosan was obtained at 400°C under N2flow along with
 1,6-anhydro-b-D-glucofuranose (8.3 %, C-based), indicating that these
 anhydrosugars are the major volatile intermediates from cellulose pyrolysis.
 Levoglucosan and other volatiles started to fragment at 600°C, and cellulose
 was completely gasified at 900°C. Most gas/tar formations are explained by
 gas-phase reactions of levoglucosan reported previously, except for some
 minor reactions originating from the molten-phase pyrolysis, which produced
 benzene, furans and 1,6-anhydro-b-D-glucofuranose. Synergetic effects of
 O2and volatiles accelerated fragmentation and cellulose gasification was
 completed at 600°C, which reduced benzene and hydrocarbon gas productions.
 The molecular mechanisms including the action of O2as a biradical are
 discussed. These lines of information provide insights into the development
 of tar-free clean gasification that maintains high efficiency.

/pdf/molecular-mechanisms-for-the-gas-phase-conversion-of-450x44cnox.pdf

Shiro Saka

Papers

Method for hydrolyzing polysaccharide substance

Decomposition behaviors of various crystalline celluloses as treated by semi-flow hot-compressed water

Useful Products from Lignocellulosics by Supercritical Water Technologies

2. The raw materials of CA 2.1 Wood as natural raw materials for cellulose acetate production

Molecular mechanisms for the gas-phase conversion of intermediates during cellulose gasification under nitrogen and oxygen/nitrogen