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 aim of this work was to develop new process for extracting and separating hydrophilic and hydrophobic compounds from coffee beans using supercritical CO2 in water. In this work, experiments and simulation of the process has been conducted. Chlorogenic acid and caffeine from coffee beans were used as model compounds of hydrophilic and hydrophobic compounds, respectively. Experiment was conducted in the semi-continuous flow extractor at various densities and ratios of coffee mass and water mass (C/W). Extracted compounds in SC-CO2 and in water were analyzed by HPLC-PDA detector, respectively. As expected, the extracted compound in SC-CO2 was containing 100% purity of caffeine. However, the extracted compound in water was containing caffeine and chlorogenic acid. It was due to the solubility of caffeine in water is higher than that in SC-CO2. Recovery of caffeine in SC-CO2 increased with increasing density and decreasing ratio of coffee mass and water mass (C/W). In addition, this process was also simulated using model based on mass transfer balance to estimate recovery of caffeine and to describe concentration profile inside of the extractor (both in SC-CO2 phase and water phase). Simulation was conducted using Visual Basic in Excel 2003. As in the experimental result, the recovery of caffeine in SC-CO2 increased with the increase in density. However, the effect of C/W on the recovery of caffeine in SC-CO2 yielded adversative result. In the simulation result, the recovery of caffeine in SC-CO2 decreased with decreasing C/W. The result can be explained that increasing mass of water caused increasing mass transfer rate of caffeine in water, thus the increasing mass transfer resistance in SC-CO2. Concentration profile of caffeine in SC-CO2 phase and in water phase inside of the extractor have also been simulated.

Caffeine and chlorogenic acid separation from raw coffee beans using supercritical CO2 in water

Pulsed discharge plasma produced in a gas/liquid environment has attracted much attention because of its low energy requirement and the generation of various radical species with high reactivity. In our previous work, a slug flow system was developed to produce gas/liquid plasma under atmospheric pressure, generating continuous bubbles and stable gas–liquid interfaces. Currently, meaningful results have also been obtained in the field of plasma under high-pressure conditions. Therefore, in this study, a slug flow system using gas/liquid discharge plasma was implemented under pressurized argon. The system pressure was controlled from 0.1 (atmospheric pressure) to 0.4 MPa, and the effect of pressure on the system was investigated. This system was also applied to the decomposition of methylene blue. The chemical reactivity was studied, and the energy of the system was calculated. The results showed that as the system pressure increased, the decomposition rate of methylene blue decreased, while the concentration of the total oxidation species increased. This can be explained by a decrease in the energy available for methylene blue decomposition owing to the steady input energy and increasing energy loss.

Gas/Liquid Pulsed Discharge Plasma in a Slug Flow Reactor under Pressurized Argon for Dye Decomposition

In this work, reactions of phenol were carried out in supercritical argon (critical temperature, Tc: 150.7 K, critical pressure, Pc: 4.8 MPa) with pulsed discharge plasma to understand reaction characteristics and to evaluate possibility that this technique will be applicable for a new “green” polymerization technique of functional polymeric materials. Experiments in subcritical water or in supercritical argon were conducted through the operation of a specially-designed SUS316 batchtype reactor (inner volume: 900 mL) at 373-523 K and 1-25 MPa, or at 303–373 K and 5 – 15 MPa, respectively. The electrode configuration consisted of a point (negative electrode) and a planar surface (positive electrode), which were made of tungsten and stainless steel, respectively. The distance between the two electrodes was fixed at 1 mm. Two kinds of power supply devices (BPFN and MPC) were employed. As results using a BPFN, it was found that reaction behavior in subcritical water at 373-523 K, 125 MPa with less than 4000 times pulsed discharges basically similar to that in supercritical argon, but polymerized products of phenol could be obtained under larger pulsed discharge times like 5000 times at identical conditions. In contrast, phenol could be converted into hydroquinone but no polymerized product could be confirmed in supercritical argon. On the surface of the electrode used, it was found that phenol could be converted into amorphous graphite oxide with pulsed discharge plasma treatment in supercritical argon. This finding will be expected as a new method for the carbon-based functional materials in supercritical argon.

https://www.jstage.jst.go.jp/article/tmrsj/35/3/35_607/_pdf

Pulsed Discharge Plasma Treatment of Phenol in Sub-critical and Supercritical Fluids for Polymer Synthesis

A set of differential equations of material balance for a twin column, two-step PSA (Pressure Swing Adsorption) was expanded into a power series of small value of half cycle time t
 c
 . The effect of finite value of cycle time on the time average product concentration CA1 started with the second order term and was interpreted by an additional resistance of mass transfer due to the difference in adsorbed amount between adsorption and desorption steps. Finally the column height L or NTU(N
 A
 = K
 A
 amL/u) required to obtain a given concentration of product gas CA1 was given by the following closed form equation for both linear and nonlinear isotherms $$\bigg\{{\frac{1}{N_A} + \frac{u_A}{u_D}\frac{1}{N_D} + \frac{1}{\nu _\Delta}} \bigg\}^{- 1} = \int_{C_{A1}}^{_ 1} {\frac{dC_A}{G(C_A) - G(C_D)},}\quad \hbox{with}\quad C_D = \frac{p_D}{p_A}C_{A1} + \frac{u_D}{u_A}(C_A - C_{A1})$$
 in which parameters Ka, L, m, p and u are overall volumetric mass transfer coefficient, column length, adsorption coefficient, pressure and superficial gas velocity, respectively. Subscript A and D refer to adsorption and desorption steps. The function G(C) is a dimensionless adsorption isotherm and the term 1/νΔ is the above mentioned additional mass transfer resistance proportional to square of t
 c
 . The performance prediction by the equation agreed well with more rigorous numerical solutions over a wide range of cycle time by introducing the additional resistance 1/νΔ. The concentration swing Δ CA1, i.e. concentration difference during a half cycle time, was also discussed in a frame of the same concept.

Extended Short Cycle Time Analysis of Pressure Swing Adsorption with Nonlinear Adsorption Isotherm

The kinetics of polyethylene terephthalate (PET) depolymerization in supercritical methanol was investigated to develop a chemical recycling process for post-consumer PET bottles. PET with a high molecular weight of IV 0.84 was depolymerized in a batch reactor at temperatures between 553 and 593 K under estimated pressures of 13 15 MPa. In addition to PET with high molecular weight, PET with low molecular weight, such as its oligomer, bis-hydroxyethyl terephthalate (BHET) and methyl-(2-hydroxyethyl) terephthalate (MHET) was used as a model reactant to clarify the depolymerization scheme of polyethylene terephthalate in supercritical methanol. The reaction products were analyzed with size exclusion chromatography, high performance liquid chromatography, and high performance liquid chromatography-mass spectrometry. The main products of each reaction were the monomers, dimethyl terephthalate (DMT) and ethylene glycol (EG). The depolymerization of high molecular weight PET to its oligomer was faster than that of oligomer to its monomer. PET was depolymerized into DMT and EG through MHET. The molecular-weight distribution showed that the depolymerization of PET proceed consecutively where the step of the oligomer to its monomer would be a rate-determining step. MHET is a relatively stable intermediate in the depolymerization. The rate constants were estimated with simple reaction models.

Motonobu Goto

Papers

Caffeine and chlorogenic acid separation from raw coffee beans using supercritical CO2 in water

Gas/Liquid Pulsed Discharge Plasma in a Slug Flow Reactor under Pressurized Argon for Dye Decomposition

Pulsed Discharge Plasma Treatment of Phenol in Sub-critical and Supercritical Fluids for Polymer Synthesis

Extended Short Cycle Time Analysis of Pressure Swing Adsorption with Nonlinear Adsorption Isotherm

Kinetic Study of Polyethylene Terephthalate Depolymerization in Supercritical Methanol