Recent technologies in the production of chemicals and bio-materials products are focusing on lignocellulosic resources since it is the world’s most abundant material, low cost, as well as sustainable. Lignocellulosic biomass consists of three main compounds: cellulose, hemicellulose, and lignin. Productions of carbon fiber from lignin as its precursor are proposed to reduce the usage of fossil fuel based materials. However, the difficulties on recovering lignin from biomass are widely known. Therefore, several studies were conducted to explore possible technologies to isolate lignin from the complex lignocellulosic biomass in simple and minimal cost. One of the potential technologies is by using sub- and supercritical fluids. The polymer made of from phenylpropane units (p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol), the building block of lignin in plants can be converted to low molecular weight compounds using sub- and supercritical fluid technology with diverse applications including carbon fiber production. Hence, this paper aims to review on the lignin extraction from lignocellulosic biomass using sub- and supercritical fluid technology as precursor for carbon fiber production.
The utilization of renewable resource such as biomass in the production of green materials as an alternative to petrochemistry is increasing due to the depleting fossil resources and the increasing CO2 emission. The present study focused on the use of tetraethoxysilane (TEOS) and dodecyltriethoxysilane (DTES) to modify surface of nanocellulose. One-pot method provides a facile and convenient route for the fabrication of hydrophobic nanocellulose-silica film as a renewable material for the water resistant packaging application. Morphological characterization of the hydrophobic nanocellulose-silica (NC-SiO2-DTES) film showed well self-assembled DTES modified silica spherical nanoparticles with an average particle size of 126 nm over the nanocellulose film. The NCSiO2-DTES film exhibited hydrophobic and superoleophilic properties simultaneously. It also performed chemical durability with an excellent hydrophobic property over a wide range of pH values. This approach is an alternative way to improve the hydrophobicity of nanocellulose films and can be applied in water resistant packaging.
The environmental performance of hydrogen production via indirect gasification of Blue Tower including the use phase by a fuel cell (FC) cell phone was evaluated following a Life Cycle Assessment (LCA) approach. Foreground data for this study were provided mainly from process simulation in consideration of the adsorption and gasification experiments. Also, the problems in the whole system were clarified, and the countermeasures for them were proposed. In the production phase, it is necessary to reduce the auxiliary power by the installation of 2-step pressure swing adsorption (2-step PSA) unit and remove the contaminants of H2S. Here, it found that H2S would be able to be entirely removed at the storage. In the use phase, sufficient H2 storage capacity and stable power supply of a FC device, which has poor load-following operation due to large over-potentials, are absolutely required in order to meet various demands. Based on the specification of a FC-cell phone with electric double-layer capacitors (EDLCs), the Life Cycle CO2 (LCCO2) emission was estimated. Bio-H2 was generally found to be a promising hydrogen fuel, with reduced greenhouse gas emissions. Especially, the negative emission had significantly impact even if the direct emission was small in comparison with the direct one.
This study focused on the synthesis of copper/carbon (Cu/C) composites through hydrothermal treatment of copper (II) acetate in the presence of xylose. The effect of the Cu content in the Cu/C composite on its electrochemical properties was investigated. The reduction of Cu2+ (CuO) to Cu1+ (Cu2O) and Cu0 was observed during the hydrothermal reaction. The structure, surface morphology and metal dispersion of the Cu/C composites with and without carbonization treatment at 550 °C for 1 h were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, respectively. The electrochemical properties of the Cu/C composites, in terms of cyclic voltammograms and galvanic charge/discharge, were investigated. The Cu/C composite formed with a 10 wt.% Cu loading by the one-step hydrothermal treatment at 190 °C for 24 h presented a good Cu dispersion on the carbon surface, and displayed a good charge transfer and high specific capacitance of up to 370 F/g.
Oil palm fronds (OPF) are potential resources for production of biomass-based chemicals such as furfural, levulinic acid, and 5-HMF due to its large abundance. Although there are various conventional methods for biomass conversion, they suffer from low yields as well as extreme reaction severity due to the usage of mineral acids as catalyst. A new method using subcritical alcohol can be an alternative. Hence, the aim of this study is to determine the feasibility of using subcritical alcohol for furfural production from OPF. The study will also determine the effect of reaction parameters such as reaction temperature, time, and types of alcohol towards the yield. From the study, it is concluded that high furfural yield can be achieved at milder temperature and moderate reaction time under subcritical conditions. The yield obtained is comparable with other conventional methods indicating that subcritical alcohol technology has the potential for furfural production.
A gasification technology, that utilizes partial oxidation (using O2 and H2O as gasifying agents) and implementation of a new high calorie gasification (using only H2O as a gasifying agent) technology, has been developed and focuses on perfect gasification of various biomass feedstocks at 900-1,000 °C with less production of soot or tar. The result of this technology is the production of a superior mixture of biogases for producing liquid biofuels through a synthetic reaction with Zn/Cu-based catalyst; or the generation of electricity through a generator. The first test plant, named “Norin Green No. 1”, began operation on April 18, 2002. A second plant named “Norin Biomass No. 3” having a new high calorie gasification technology, began operation on March in 2004. In 2009, with the support of Ministry of Agriculture, Forestry and Fisheries (MAFF), a large commercial plant was established in Nagasaki to utilize discarded woods for potentially capable of producing biomethanol (100 L/hr). The future of these technologies and the practical plants, production and utilization of the mixture of gases from the technologies within these plants is discussed.
The environmental footprint for microalgae based biofuel can be reduced by coupling the microalgae cultivation with wastewater treatment. In the present study, the nutrients source for microalga Chlorella vulgaris was replaced by municipal wastewater from wastewater treatment plant located at USM Engineering Campus, Penang. All cultivation experiments were conducted in 5 L photobioreactors (PBRs) under indoor condition with illumination from artificial lights and compressed-air aeration. The growth performances of microalga C. vulgaris and nutrients uptake from wastewater were monitored throughout a 13-day cultivation period. The nutrients removal efficiency (NRE) for total nitrogen (TN) and total phosphorus (TP) by microalgae are 72.1 wt% and 89.7 wt%, respectively under the optimum cultivation conditions. Subsequently, microalgae biomass was collected by flocculation method, followed by extraction of lipid and transesterified to biodiesel. It was found that the biomass collected under optimum cultivation conditions achieved a maximum biomass dry weight density (N) of 0.76 g/L (or an equivalent biomass daily productivity, P of 58.6 mg/(L･d)).
Biomass-derived hydrogen (Bio-H2) has been attracting much attention as a low environmental load type of hydrogen. Among the potential applications of Bio-H2, use as a fuel for polymer electrolyte membrane fuel cells (PEMFCs) would require the removal of contaminants. Therefore, we propose the use of metal hydride for the purification and storage of Bio-H2. Metal hydride can store a larger volumetric amount of hydrogen than that under high-pressure or liquefied, and the hydrogenate is processed at near atmospheric pressure and room temperature. In addition, by exploiting the selective hydrogen absorption properties of metal hydride, we have successfully reduced the concentration of methane as well as carbon monoxide and carbon dioxide in the hydrogen using a lanthanumrich mischmetal alloy, the storage performance of which was evaluated in our previous study. Pressure swing adsorption was used to reduce the contaminant concentration, which was measured as 3% methane. For practical application, the influence of methane on the hydrogen absorption performance of the metal hydride is examined and the hydrogen recovery rate over the hydrogen absorption and desorption processes is evaluated.
Viscosity of a solution is a convenient method to indirectly estimate the size of the solute in the solution. The current work investigates the viscosity of the solutions with different vegetable oil concentrations in two solvents, i.e., methyl ethyl ketone and tetrahydrofuran. The Huggins equation has been then applied to determine the intrinsic viscosity and the Huggins constant which are related to the size of the solute and the intermolecular interaction of solute in the solution, respectively. According to the results, intrinsic viscosities of vegetable oils increase following the order coconut oil (CO), sunflower oil (SF), and palm oil (PO). However, the intermolecular interaction is following the reverse order. This result is in accordance with our previous research on the relationship between molecular weight of triglyceride and its transesterification reaction rate in methyl ethyl ketone.
A small scale demonstration plant was designed to produce upgraded wood fuel by torrefaction. Before starting continuous production, we conducted preliminary torrefaction and pelletization of Japanese cedar. Then combustion test of the torrefied fuel was done using a commercial pellet stove. The main characteristics, such as bulk density, moisture content, and mechanical durability, met the ISO TS 17225-8 guidelines. No time delay and less smoke during ignition were observed when operating the stove using torrefied pellets.
Recently, Rubber Seed Oil (RSO) has been considered as a promising potential oil source for biodiesel production. However, like other non-edible feedstocks, RSO contains a significant amount of high free fatty acids which affect the process of biodiesel production. In the present work, microwave-assisted esterification process was conducted as a pre-treatment step to reduce the high free fatty acid (FFA) content of RSO from 40.14% to less than 1%. Response surface methodology (RSM) involving central composite design (CCD) was employed in the design of experiments (DOE) and the optimization of esterification reaction. The optimum conditions were found at 60 °C, with methanol to oil molar ratio of 19.94:1, H2SO4 catalyst of 7.93 wt% and reaction time of 23 min. The result shows that methanol to oil molar ratio was the most influencing parameter towards the FFA reduction followed by temperature, whereas the catalyst loading and the reaction time both were observed to be insignificantly effective.
Liquefaction of oil palm trunk (OPT) in ethylene glycol and glycerol, with H2SO4 as a catalyst, at a temperature of 150 °C was conducted based on Design of Experiment (DoE) aided by software Stat-Ease Inc., Design-Expert® Version 7. A 24-1 fractional factorial design was used. The results showed that factors such as types of solvents, percentage of H2SO4 catalyst and liquefaction time influenced the final liquefaction yield. Liquefaction of OPT in glycerol gave higher amount of liquefied yield. Besides, higher percentage of H2SO4 catalyst and longer liquefaction time also gave higher liquefaction yields.
Preparation, characteristic, and activity of CuO/γ-Al2O3 as re-generable SO2 adsorbent have been studied. The model gas containing SO2 of about 2,500 mg/m3 (700 mmHg, and 27 °C) was made to simulate the flue gas from combustion of algae biomass: Enteromorpha and Chlorella. Experiments were carried out in a tubular reactor electrically heated to maintain adsorption temperature of 300, 350, 400 or 450 °C. Amount of adsorbent was 1, 2, 4, or 8 g, and the gas flow rate was set at 1.21 L/min (700 mmHg, and 27 °C). Adsorbent with CuO content of about 7.5%-mass could adsorb SO2 successfully and release the outlet gas with a SO2 concentration to meet the national standard of SO2 emission of 750 mg/Nm3. Naturally, the more amount of adsorbent in the reactor, the more complete conversion of SO2 and the lower utilization of CuO.
Spherical silica nanoparticles were fabricated from sodium metasilicate solution using urea as a precipitant. Homogeneity of the silica particles was improved by adjusting the ratio of sodium metasilicate to urea, and their size was adjusted between 20 and 1600 nm by adjusting the amount of sodium metasilicate and urea. Supported ruthenium catalysts were prepared by impregnation method using the silica spheres as a support of the catalysts. The amount of supported ruthenium depended on the ruthenium concentration during the impregnation process. The catalytic activity for hydrogenation of carbon dioxide into formic acid increased with increasing their ruthenium contents. The activity did not significantly depend on the particle size of the silica supports; however, the amount of ruthenium deposited on the particles depended on the particle size of the silica supports, with a larger amount of ruthenium being immobilized on the silica supports with a smaller particle size.
Methanol is an important industrial material for the production of medicines, fuels, and resins. Methanol is generally synthesized under catalyst by reacting CO and H2 through steam reforming of methane. This process is, however, energy consuming. Hence, a direct methanol synthesis method, which is less energy consuming, should be developed. The authors conducted flow-type partial oxidation of methane using the Fenton reaction under hydrothermal conditions for the direct synthesis of methanol from methane. Parameter variation included reaction temperatures of 100-250 °C, reaction times of 2-31 s, and initial H2O2/CH4 molar flow rate ratios of 0.5-2.0. The methane conversion using the Fenton reaction was higher than that of the catalyst-free conversion at temperatures of less than 200 °C. The methane conversion reached the highest value of 6.04% at T = 200 °C, τ = 31 s, and H2O2/CH4 = 2.0. Hence, it can be concluded that the Fenton reaction prompted the formation of hydroxyl radicals, reactive species. However, the methane conversion by the Fenton reaction decreased rapidly at T = 250 °C, resulting in a lower conversion value than that of the catalyst-free reaction.