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 design of clean, efficient and environmentally friendly routes that reduce the waste production and fuel emissions of pollutants into the atmosphere, produce clean, affordable, and renewable energy sources to lessen energy consumption and toxicity on the environment, has become a central issue of chemical research both in industry and academia. One of the approaches being used in green chemistry practices is to use water as a solvent and reaction medium where possible. Much of this work deals with liquid water at temperatures exceeding the normal boiling point which is denoted as sub-critical water. Electrochemical reaction, usually operated at atmospheric condition in water, is generally slow, although it has advantages over chemical reaction such as suppression of side reaction by tuning operating conditions. Since sub-critical water (7 MPa and 250 °C) has remarkable properties such as high ion product and low dielectric constant, it could be a suitable reaction media. We have been studying electrolysis of organic compounds in sub-critical water as waste treatment and molecular degradation technologies. Electrolysis in sub-critical water could degrade harmful and thermally stable organic compounds into innocuous compounds such as hydrogen and water. In this research, we focused on the investigation of the electrochemical reactions of alcohols in sub-critical water to evaluate possibility for the selective production of hydrogen and value-added chemicals. Electrochemical reactions were carried out in sub-critical water using a specially designed autoclave made of SS 316 with a volume of 500 mL. For comparison, thermal degradation experiments of alcohols were also conducted without any direct current loading at identical conditions. Here we employed glycerol and 1-butanol as model compounds of alcohols. As a result of 1-butanol experiments, butanal and butyric acid were produced via partial oxidation at 250 °C and by applying 1-3 A of direct current while no oxidation products were observed at the hydrothermal degradation run. As a gaseous product, hydrogen gas was generated according to the electrochemical reaction mechanism. In the case of glycerol experiments, the main gaseous product was hydrogen gas, whereas glycolaldehyde, lactic acid, and formic acid were generated as the main liquid products at 280 °C. Results indicated that greater than 92% of the glycerol could be decomposed under optimum conditions by hydrothermal electrolysis technique. This presented research will help to degrade stable organic materials in an environmentally friendly way and without need for secondary treatment processes. It will also address the need for novel more efficient techniques for the degradation of stable organic compounds in aqueous conditions and it will advance the use of water as a reaction medium in an efficient way without any organic solvent.

/pdf/electrolysis-of-alcohols-in-high-temperature-high-pressure-3enswim3ac.pdf

Electrolysis of alcohols in high temperature-high pressure water

Precious metal recovery was realized in this study using the electrowinning technique under subcritical water conditions. The experiments were performed in a batch system at temperatures of 110–200 °C with reaction times of 60–300 min. Electric currents of 1–3 A were applied to an electrolyte solution containing Co and Li as target elements via stainless steel (SUS) electrodes. SEM/EDS and XRD analyses indicated that the metallic elements in the deposited metal on the cathode cell surface comprised Co as the primary element. Inductively coupled plasma atomic emission spectroscopy suggested that the Co yield independently increased with increases in operating parameters such as reaction time, reaction temperature, and applied electric current. The Co yield approached 56.2% when the experiment was conducted at 200 °C with an applied electric current of 1.0 A for 300 min. The technique described herein is innovative and practical for advanced precious-metal recovery based on the use of electric current in a one-step process. • Leaching and electrowinning were performed under subcritical water conditions. • Changing operating parameters affect the deposited chemical composition product. • This process is an innovative and applicable method for precious metal recovery. 

http://manuscript.elsevier.com/S0896844621003430/pdf/S0896844621003430.pdf

Subcritical water electrolysis for cobalt recovery from spent lithium-ion batteries in an acidic environment

In this paper, we introduce novel findings that we have obtained through the several experimental techniques with high-voltage pulsed power in high-density fluids (such as subcritical water, supercritical carbon dioxide or supercritical argon). In laser ablation in supercritical carbon dioxide, we succeeded in the synthesis of gold nanoparticles from gold substrate. Next, we were able to produce hard amorphous carbon thin film from typical organic chemicals such as phenol and aniline. Furthermore, by using a novel technique ``electro-spinning in supercritical carbon dioxide'', we succeeded to prepare unique morphology fibers such as hollow or balloon-like structures in one step. [pulsed power, pulsed discharge, supercritical fluids, amorphous carbon, laser ablation, nanoparticles, electrospinning, nanofibers]

Preparation of Nano-Sized Materials with Pulsed Power Irradiation in Supercritical Fluids

Isothiocyanate-functionalized silica as an efficient heterogeneous catalyst for carotenoid isomerization.

Fine particles comprising Curcuma xanthorrhiza Roxb (C. xanthorrhiza) rhizome extract were successfully generated using a supercritical carbon dioxide (SCCO2) antisolvent technique. The SCCO2 antisolvent process was performed at 40 °C with 8–16 MPa operating pressures. The CO2 and feed solution flow rates were 15 and 0.25 mL min–1, respectively. The mixture of C. xanthorrhiza rhizome extract and a polyvinylpyrrolidone (PVP) polymer in acetone–ethanol was used as a feed solution. The collected particle products seemed to possess spherical and spherical-like morphologies with a diameter of less than 500 nm. The infrared spectroscopy analysis showed that the structural properties of C. xanthorrhiza rhizome extract did not change after treatment with the SCCO2 antisolvent. Furthermore, the addition of the PVP polymer in the C. xanthorrhiza rhizome extract particle products may improve their dissolution significantly in an aqueous solution medium.

https://pubs.acs.org/doi/pdf/10.1021/acsomega.1c06911

Motonobu Goto

Papers

Electrolysis of alcohols in high temperature-high pressure water

Subcritical water electrolysis for cobalt recovery from spent lithium-ion batteries in an acidic environment

Preparation of Nano-Sized Materials with Pulsed Power Irradiation in Supercritical Fluids

Isothiocyanate-functionalized silica as an efficient heterogeneous catalyst for carotenoid isomerization.

Enhancement of Curcuma xanthorrhiza Roxb Phytochemical Dissolution via Micronization Using a Supercritical Antisolvent Technique