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

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

Renewable Resources Robert-Jan van Putten,†,‡ Jan C. van der Waal,† Ed de Jong,*,† Carolus B. Rasrendra,‡,⊥ Hero J. Heeres,*,‡ and Johannes G. de Vries* †Avantium Chemicals, Zekeringstraat 29, 1014 BV Amsterdam, the Netherlands ‡Department of Chemical Engineering, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands DSM Innovative Synthesis BV, P.O. Box 18, 6160 MD Geleen, the Netherlands Department of Chemical Engineering, Institut Teknologi Bandung, Ganesha 10, Bandung 40132, Indonesia

Hydroxymethylfurfural, A Versatile Platform Chemical Made from Renewable Resources

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).

Conversion of biomass to selected chemical products

Various novel techniques including ultrasound-assisted extraction, microwave-assisted extraction, supercritical fluid extraction, and accelerated solvent extraction have been developed for the extraction of nutraceuticals from plants in order to shorten the extraction time, decrease the solvent consumption, increase the extraction yield, and enhance the quality of extracts. A critical review was conducted to introduce and compare the conventional Soxhlet extraction and the new alternative methods used for the extraction of nutraceuticals from plants. The practical issues of each extraction method were discussed. Potential uses of those methods for the extraction of nutraceuticals from plant materials was finally summarized.

Recent advances in extraction of nutraceuticals from plants

The crystalline TiO2 powders were prepared by highly reactive supercritical fluid with unique properties of both liquid and vapor phases. In this research, the effects of stirring and heating rates on the crystallization behavior of the TiO2 powders were investigated. The crystalline size of the TiO2 powders decreased from 90 to 60 nm as the stirring rate increased from 0 up to 150 rpm but increased to 160 nm with a further increase of the stirring rate to 400 rpm. The TiO2 crystals tend to develop into spherical shape at a stirring rate below 50 rpm. The morphology of the TiO2 particles changed from spherical to platelet shape as the stirring rate increased from 400 to 600 rpm. The particle size of the TiO2 powders increased from 200 to 400 nm as the heating rate increased from 3 to 12 °C/min, but the shape of the TiO2 powder became more spherical.

Effect of Stirring and Heating Rate on the Formation of TiO2 Powders Using Supercritical Fluid

Porcine aortic tissue was decellularized by subcritical dimethyl ether (DME) used as an alternative to the surfactant sodium dodecyl sulfate. The process included three steps. For the first step, lipids were extracted from the porcine aorta using subcritical DME at 23 °C with a DME pressure of 0.56 MPa. Next, DME was evaporated from the aorta under atmospheric pressure and temperature. The second step involved DNA fragmentation by DNase, which was primarily identical to the common method. For the third step, similar to the common method, DNA fragments were removed by washing with water and ethanol. After 3 days of DNase treatment, the amount of DNA remaining in the porcine aorta was 40 ng/dry-mg, which was lower than the standard value of 50 ng/mg-dry. Hematoxylin and eosin staining showed that most cell nuclei were removed from the aorta. These results demonstrate that subcritical DME eliminates the need to utilize surfactants.

Surfactant-Free Decellularization of Porcine Aortic Tissue by Subcritical Dimethyl Ether.

A new pressure swing adsorption process was proposed for treatment of low-VOC-concentration air streams. Feed gas is supplied to the high pressure column at some intermediate position to divide it into an enriching and a stripping sections. A part of air stream leaving the high pressure column is returned to the low pressure column as stripping reflux while air stream leaving the low pressure column is returned totally to the high pressure column as enriching reflux. With this dual reflux policy, VOC vapor can be enriched in the enriching section up to a concentration high enough to be condensed in liquid state as well as VOC free air is produced in the stripping section. High efficiency of the dual reflux PSA was confirmed experimentally in a lab-scale unit with a model system of ethanol-activated carbon for various parameters such as half cycle time, feed rate, feed inlet position etc. The optimum feed inlet position was found experimentally and its behavior was interpreted based on an analytical simulation by short cycle time approximation.

Dual Reflux PSA Process Applied to VOC Recovery as Liquid Condensate

The rates of thermal decomposition of cellulose from wood pulp in the presence of supercritical tert-butyl alcohol were measured dynamically in a continuous-flow system. The decomposition rate increased markedly with temperature. A kinetic model is presented for the supercritical thermal decomposition process. A three-reaction model, which consists of consecutive reactions to produce cellulose derivatives accompanying competitive char formation from the intermediate product, satisfactorily represents the data. The kinetic parameters for the reaction estimated from the model analysis were compared with pyrolysis results under vacuum. The rate of char formation for the supercritical process was typically smaller than that of pyrolysis

Supercritical thermal decomposition of cellulose: Experiments and modeling

Synergistic effects of utilizing subcritical water and supercritical carbon dioxide were investigated for the hydrolysis of hesperidin into more valuable compounds at a pressure range of 10–25 MPa and temperature of 110–140 °C. The effect of operating conditions such as pressure, temperature, reaction time, and addition of cosolvent such as ethanol were found to affect the hydrolysis rate. Higher yields were obtained at higher carbon dioxide pressure owing to an increase in formation of carbonic acid. Moreover, the rate of reaction was also found to increase with increasing temperature, obtaining higher yields of the main products, hesperetin-β-glucoside and hesperetin. Addition of ethanol as a cosolvent could increase solubility of hesperidin, however, it inhibited the reaction and formation of carbonic acid. At the maximum temperature of 140 °C and pressure of 25 MPa investigated in this work, the highest concentration of hesperetin-β-glucoside of 4.2 mol/L was obtained in a reaction time of 2 h, wherea...

Motonobu Goto

Papers

Effect of Stirring and Heating Rate on the Formation of TiO2 Powders Using Supercritical Fluid

Surfactant-Free Decellularization of Porcine Aortic Tissue by Subcritical Dimethyl Ether.

Dual Reflux PSA Process Applied to VOC Recovery as Liquid Condensate

Supercritical thermal decomposition of cellulose: Experiments and modeling

Hydrothermal Hydrolysis of Hesperidin Into More Valuable Compounds Under Supercritical Carbon Dioxide Condition