Showing papers by "Motonobu Goto published in 2002"

Degradation kinetics of polyethylene terephthalate in supercritical methanol

Abstract: Degradation of polyethylene terephthalate (PET) in supercritical methanol was investigated to develop a chemical recycling process for waste plastics. Continuous kinetics analysis was applied to the experimental data. A batch reactor was used at 573 K under the estimated pressure of 20 MPa for a reaction time of 2-120 min. PET decomposed to its monomers, dimethyl terephthalate (DMT), and ethylene glycol (EG), by methanolysis in supercritical methanol. PET with a weight-average molecular weight of about 47,000 was converted to oligomer with that of 3,000 in 300 s and with that of 1,000 in 600 s. The largest yield of DMT was 80 mol % at 7,200 s and that of EG was 60 mol % at 3,600 s. Reaction products were analyzed with size exclusion chromatography, gas chromatography-mass spectrometry, and reversed phase liquid chromatography. The molecular-weight distribution (MWD) of the products was obtained as a function of reaction time. The yields of monomer components of the decomposition products, including byproducts, were measured. Continuous kinetics theory was developed to analyze the decomposition behavior. The theory includes MWD change of polymer by random and specific scissions and secondary reactions for monomer components. Change of MWD and monomers as a function of time was simulated by the continuous kinetics.

Depolymerization of polyethylene terephthalate in supercritical methanol

Abstract: The degradation of polyethylene terephthalate (PET) in supercritical methanol was investigated with the aim of developing a process for chemical recycling of waste plastics. A batch reactor was used at temperatures of 573–623 K under an estimated pressure of 20 MPa for a reaction time of 2–120 min. PET was decomposed to its monomers, dimethyl terephthalate and ethylene glycol, by methanolysis in supercritical methanol. The reaction products were analysed using size-exclusion chromatography, gas chromatography–mass spectrometry, and reversed-phase liquid chromatography. The molecular weight distribution of the products was obtained as a function of reaction time. The yields of monomer components of the decomposition products including by-products were measured. Continuous kinetics analysis was performed on the experimental data.

Semi-batch operation and countercurrent extraction by supercritical CO2 for the fractionation of lemon oil

Abstract: The supercritical fluid extraction of cold-pressed lemon oil was carried out in semi-batch and continuous countercurrent modes. In order to observe the extraction behavior of lemon oil, semi-batch extraction was performed using a rectification column, and the distribution curve for the main constituents of lemon oil was obtained. Separation was improved by applying an internal reflux induced by a temperature gradient along the column. The effects of the reflux on the extraction ratio, the separation selectivity, the concentration factor of each component and the recovery of oxygenated compounds were investigated for continuous operation at pressures of 8.8 and 9.8 MPa. Extraction combined with side-stream withdrawal was useful for lemon oil processing. The continuous operation with a linear temperature gradient from 313 to 333 K at 8.8 MPa showed the highest selectivity. Selectivity increased with the increase in solvent-to-feed (S/F) ratio.

On-line Extraction−Reaction of Canola Oil with Ethanol by Immobilized Lipase in SC-CO2

Abstract: On-line extraction−reaction was carried out in supercritical carbon dioxide (SC-CO2) in the temperature range from 308 to 328 K and the pressure range from 24 to 35 MPa. Fatty acid ethyl esters were synthesized from extracted canola oil with ethanol by using the immobilized lipase (Lipozyme IM). The effects of ethanol amount, enzyme load, and operational conditions on the amount of fatty acid esters (FAE), free fatty acids (FFA), and mono-, di-, and triglycerides (MG, DG, and TG, respectively) present in the product were investigated. The results show that it is possible to synthesize fatty acid ethyl esters efficiently at high temperature. Finally, a new process operating at different extractor and reactor temperatures was proposed.

Separation performance of supercritical carbon dioxide extraction column for the citrus oil processing: observation using simulator

Abstract: Phase behavior of limonene and linalyl acetate, which are principal constituents of terpenes and oxygenated compounds, respectively, in bergamot oil, with supercritical carbon dioxide (SC-CO2) was observed by use of process simulator (SIMSCI PRO/II). Solubility of each pure component in SC-CO2 was calculated by the Peng–Robinson equation of state. For a given calculating condition, the solubility of limonene was 2–5 times higher than that of linalyl acetate. Process flow diagram for the citrus oil processing by SC-CO2 extraction column was successfully constructed to evaluate the separation performance. The effects of feed composition, feed inlet position, reflux ratio, and stage number on the extraction ratio of limonene, separation selectivity, and recovery of linalyl acetate were studied at 333K and 8.8 MPa.

Method of collecting citrus oil and aurapten

Abstract: PROBLEM TO BE SOLVED: To provide a method of collecting citrus oil in a high yield without using any organic solvent, and to provide a method of collecting an aurapten without using any organic solvent. SOLUTION: In the method of collecting citrus oil, a citrus oil is collected by applying a centrifugal acceleration of 1×10 5 G or greater to a citrus squeezed liquid. The method of separating aurapten from the citrus oil is performed by a supercritical carbon dioxide chromatography. COPYRIGHT: (C)2004,JPO

Deterpenation of bergamot oil by pressure swing adsorption in supercritical carbon dioxide

Abstract: Bergamot oil is a kind of citrus oil which contains terpenes, oxygenated compounds, and waxes. Terpenes were removed conventionally by vacuum distillation or solvent extraction. Recently, supercritical carbon dioxide is focused as an alternative solvent for citrus oil processing. A fractionation process of bergamot oil was developed by using a pressure swing adsorption (PSA) concept in supercritical carbon dioxide. The objective of the fractionation is to separate oxygenated compounds from terpenes (deterpenation). The pressure swing operation between the adsorption step at a lower pressure and the desorption step at a higher pressure was carried out with silica gel as adsorbent. Oxygenated compounds were satisfactorily concentrated in the desorption step and the de-pressurization step. A mathematical model simulated the performance of the PSA process. An increase in the pressure ratio (desorption/adsorption) gave high purity, recovery and yield in the desorption step. The purity of 0.84 was obtained in the desorption step at a pressure ratio of 2.5. Model calculations agreed roughly with the experimental results, although the mathematical model was simple.

Performance and characteristics of a BaO2-MgO oxygen acceptor

Abstract: The performance and the characteristics of an oxygen acceptor prepared from barium peroxide and magnesium oxide were investigated for application to oxygen production. Reaction was run in an isothermal and isobaric condition, and the effects of temperature, oxygen pressure and the size of a sample pellet on the BaO-BaO2 equilibrium and reaction rate were investigated over a range of temperature 973–1173 K and oxygen pressure 0–0.3 MPa. It was found that both oxidation of barium oxide and reduction of barium peroxide are the first order reaction, and the BaO-BaO2 equilibrium and reaction rate vary markedly by the change of temperature and/or oxygen pressure but little affected by the size of a sample. Low temperature and high oxygen pressure are favorable to oxidation, and high temperature and low oxygen pressure are favorable to reduction. A reaction rate constant is independent of the starting BaO-BaO2 composition under fixed values of temperature and oxygen pressure. For a fixed equilibrium composition in oxidation or reduction, rate constants (ko + kr) at different temperatures are nearly the same. In the whole range of equilibrium composition, a rate constant ko increases with an increase in the mole fraction of barium peroxide at new equilibrium, while a rate constant kr increases with an increase in the mole fraction of barium oxide at new equilibrium.

Decomposition process development of Dioxins in the fly ash by improved supercritical water oxidation method

Abstract: Supercritical Carbon dioxide Extraction (SCE) technology was combined with Supercritical Water Oxidation (SCWO) technology in order to efficiently and perfectly decompose the dioxins which are thinly distributed in the fly ash from municipal waste incinerator. At first, Dioxins in the incineration fly ash was extracted using the supercritical carbon dioxide. In the condition of Pressure :60MPa, Temperature: 40°C, Extraction time: lhour, it was possible to extract dioxins over 99% from the incineration fly ash.Next, dioxins in incineration fly ash were decomposed using the sub-critical and supercritical water. It was possible to almost perfectly (99.9999%) decompose dioxins in incineration fly ash inthe sub-critical (10MPa, 15MPa, 600°C) and supercritical water(25MPa, 500°C, 600°C).