Over the past several decades, inorganic membranes composed of zeolite, silica, carbon, and metal/organic frameworks (MOF) have improved dramatically in terms of fabrication and application. Pure silica (SiO2) and organosilica membranes for use in molecular separation are the focus of this review. First, the fabrication of these silica-based membranes is outlined to highlight the great progress achieved in sol–gel and CVD processing. Then, applications in gas- and liquid-phase separations and an evaluation of pore sizes are summarized and future perspectives are discussed.
Thermochemical hydrogen production by the iodine-sulfur process decomposes water into hydrogen and oxygen by combining the chemical reactions of iodine (I) and sulfur (S). Two types of acids are produced through the Bunsen reaction (I2+SO2+H2O=2HI+H2SO4). To improve the performance of this reaction, ion-exchange membranes for the membrane Bunsen reaction should be developed. In the present study, a cation-exchange membrane was prepared using a radiation-graft polymerization method. It was found that a divinylbenzene crosslinking procedure was very effective in reducing water permeation through the membrane, and the membrane Bunsen reaction was successfully carried out by using the developed crosslinked membrane. Moreover, sulfur deposition during the membrane Bunsen reaction was low for the crosslinked membrane. Therefore, the developed crosslinked membrane is a potential candidate as a cation-exchange membrane for the membrane Bunsen reaction.
Silica-based membranes were prepared by atmospheric-pressure plasma-enhanced chemical vapor deposition. The effects of membrane preparation parameters such as thermal annealing temperature and precursor on their gas permeation properties were investigated by assessing the temperature dependence of their gas permeances. Thermal annealing was effective for the improvement of membrane performance owing to the formation of permselective pores via partial decomposition of organic components in the plasma-deposited layer. The membrane prepared using hexamethyldisiloxane (HMDSO) as a silicon precursor and annealed at 400°C in N2 showed a high H2 permeance of 1.6×10−6 mol m−2 s−1 Pa−1 with H2/N2 and H2/SF6 permeance ratios of 53 and 1,800, respectively, at 300°C. High carbon-content structures were obtained by plasma-deposition of HMDSO mixed with a second precursor (1,5-cyclooctadiene) or a carbon-rich silicon precursor (triethylsilane). Gas permeation measurements revealed that a higher the carbon content in the plasma-deposited layer leads to a higher activation energy of permeation.
The characteristics of three-phase (gas–liquid–solid) circulating fluidized beds (TPCFBs) are discussed in order to visualize the unique features and advantages thereof due to the intrinsic flow and contacting behaviors of multi-phases, providing a better understanding of the state of art of TPCFBs and their feasible applications as multi-phase reactors and contactors. The hydrodynamics such as individual phase holdups, bubbling flow behaviors, bubble properties and liquid phase dispersions, and heat and mass transfer characteristics in the riser were examined based on the previous investigations. Although the information in the riser of various kinds of TPCFBs deviated from each other depending on the solid circulation modes and experimental conditions, they were summarized and consociated for the elucidation of the present states and views of the investigations. Rational guides to predict the hydrodynamics and heat and mass transfer phenomena in the riser of the TPCFB were possible by analyzing and synthesizing the results reported in the literatures presently available. Especially, the effects of operating variables including gas (UG) and liquid (UL) velocities, properties of fluidized solid particles and continuous liquid media, and solid circulation rate (Gs) on the hydrodynamic parameters and the heat and mass transfer characteristics such as heat transfer coefficient (h) and resistance, volumetric mass transfer coefficient (kLa), gas–liquid interfacial area (a) and liquid side mass transfer coefficient (kL) were determined. The information on the heat and mass transfer, however, were extremely limited comparing with those of hydrodynamics. Some correlations were suggested to predict the hydrodynamic parameters, and the values of h, kLa, a, and kL in the riser of the TPCFBs to provide insights for the present and future studies. The mechanism of heat and mass transfer and their modeling should be conducted for the better prediction of the performance of the TPCFB-reactors and contactors in the future.
To investigate the energy potential of liquid foundry wastes, the co-firing of coal and two waste solvents with relative smaller heating value was studied in a bubbling fluidized bed combustor. The effects of the bed temperature, liquid fuel type, liquid ratio, and the particle size of coal on the co-firing characteristics and pollutant emissions characteristics were investigated. The results showed that the co-firing of coal and waste solvent can be adopted as an alternative for waste disposal, ensuring energy recovery and waste disposal in a single step. NO emissions are still dependent on the total nitrogen content in the fuel feeding material. For the two waste solvents, NO emission increases with liquid ratio, and the highest value was 447.5 ppm, which exceeds the NO emission requirement. Increased bed temperature had little effect on the co-firing characteristics of coal with waste solvents, but the NO emission significantly increased from 137 to 319 ppm as the bed temperature increased from 750 to 850°C. Decreasing the coal particle size increases the CO emission, which creates the proper atmosphere for NO reduction.
A series of copper manganese mixed oxide catalysts Cu1−xMnx (x=0–1.0) with high surface area were synthesized by using the carbonate co-precipitation method and their performance in the catalytic combustion reaction of toluene was investigated by varying the mole ratio of Cu and Mn. TG, XRD, H2-TPR, DRIFT, XPS and N2 adsorption/desorption were used to characterize the structure and textural properties of catalysts. The resulting Cu1−xMnx catalyst showed higher catalytic activity than the mono-metal oxide catalyst, especially when a small amount of copper was doped into manganese oxide. With increasing the manganese content from 0 to 1.0, a volcanic tendency for catalytic activity was observed. Results of catalyst characterization revealed that the promoted catalytic activity can be associated with some interrelated factors, such as depressed crystallinity, highly dispersed oxide species onto the other, easier catalyst reducibility, more surface oxygen and enhanced surface area. It was difficult to attribute the promoted catalytic activity only to a single and specific factor. A synergistic effect between manganese and copper species was considered to be the most intrinsic reason.
With the aim of the efficient use of plant oils as alternative fuels, the deoxygenation of saturated and unsaturated triglycerides in a catalytic cracking process was investigated using a fluid catalytic cracking catalyst with enhanced hydrogen-transfer activity. The decomposition and deoxygenation of sunflower oil (unsaturated triglycerides) proceeded rapidly and produced a large amount of aromatic hydrocarbons, which are unsuitable for fuel applications. In contrast, the rate of deoxygenation of coconut oil (saturated triglycerides) was slow and some oxygen-containing species were observed as products. During the co-processing of saturated and unsaturated triglycerides, the deoxygenation of saturated triglycerides was accelerated and complete deoxygenation was achieved. The acceleration of the deoxygenation reaction was attributed to the rapid formation of hydrogen donors, such as olefins and naphthenes, from the decomposition of unsaturated triglycerides. The olefins and naphthenes released hydrogen species by cyclization and aromatization reactions. These hydrogen species then reacted with saturated triglycerides and their derivatives (fatty acids and aldehydes) in hydrogen-transfer reactions, accelerating the hydrodeoxygenation of saturated triglycerides. The hydrodeoxygenation of saturated triglycerides produced paraffins and olefins rather than aromatics. The increase in the amount of paraffins and olefins produced by the accelerated deoxygenation of saturated triglycerides was larger than the amount of aromatic hydrocarbons derived from unsaturated triglycerides. Thus, co-processing of saturated and unsaturated triglycerides was confirmed to be effective for simultaneously achieving both the acceleration of saturated triglyceride deoxygenation and the suppression of aromatic hydrocarbon formation.
For environmental sustainability, lignocellulose is substituted for crops as a renewable source for biofuel production. Because of the network of intra- and intermolecular hydrogen bond in the crystalline structure of cellulose, the rigid structure of cellulose is difficult to convert into sugars under mild conditions. Therefore, the efficient process of destroying the recalcitrant structure of biomass is the core technology for the conversion of biomass into sugars. The novel technique of lignocellulose hydrolysis in ionic solution, which comprises ZnCl2 and formic acid, is investigated. In this ionic solution, biomass can be efficiently dissolved and hydrolyzed into reducing sugars, with a nearly 96% yield of reducing sugar from cellulose and a 90–100% yield of reducing sugar from crude biomass. Through 7 extraction stages, formic acid and ZnCl2 was extracted by tributyl phosphate from the ionic solution with the separation rate of 99.8 and 95.5%. These results show that this ionic solution is an effective medium for lignocellulose hydrolysis and can be recovered by liquid-liquid extraction. All experiment conditions can be used accordingly to develop a new hydrolysis technique for cellulosic sugar production.
Porous silicon (Si) has lots of potential applications including anode in lithium-ion batteries, sensor, electronic, or biomedical field. The synthesis of porous Si usually involves the use of expensive precursors with complex methods, having difficulties in the application to scalable process. It is urgent to find a massive production method for the production of porous Si using inexpensive and abundant source. Here, we show that the cheap and abundant rice husk silica (RH-SiO2) can be converted into porous Si via magnesiothermic reduction in a self-propagating high temperature synthesis (SHS) approach. The SHS method is a simple and commercial method by pelletizing the powder reactants. The Si yield and physical properties were investigated varying temperatures in a range from 600 to 900°C and pelletizing pressure from 5 to 30 MPa in order to find the optimum process condition. The high temperature at 900°C increased the Si yield avoiding the unwanted by-product such as Mg2SiO4. And the pellet sample under pelletizing pressure of 10 MPa showed an efficient heat/mass transfer by sustaining an optimum proximity between particles. The meso- and micro-structured Si was observed in SEM/EDX analysis and battery test shows performance of 171.7 mA h/g was retained after 150 cyclic tests.
This study discusses the status of mercury (Hg) emissions and distribution from major anthropogenic sources and the future trend of Hg emissions by activity changes and application of Best Available Technologies (BATs) in South Korea. Atmospheric Hg emission from major anthropogenic sources, based on Annex D of the Minamata Convention, was estimated at approximately 4.48 t in 2014. Emission ratios of Hg by cement clinker production, coal-fired power plants, waste incineration, and non-ferrous metal smelting were 59.8%, 26.6%, 13.8%, and 0.22%, respectively. For this reason, the high Hg emission regions are characterized by the presence of cement clinker production facilities and coal-fired power plants. The future activities of such emission sources were predicted using linear regression with moving averages of the previous activities. The predicted results reveal that the Hg emissions from major sources will increase to 6.06 t in 2022. In addition, the amount of Hg emitted into the atmosphere could be reduced by applying BATs resulting in a decrease to 2.66 t in 2022. In this scenario, the Hg emissions from coal-fired power plants and cement clinkers facilities are expected to decrease significantly.
Biofuel from microalgae is an alternative to petroleum because growth rate of microalgae is high and also microalgae contain lots of lipids. In this study an attempt is made to optimize both heat and power consumption of the hexane recovery section after lipid extraction by introducing mechanical vapor recompression (MVR) or self-heat recuperation (SHR) technology. We evaluated primary energy consumption in the base case, MVR and SHR models of the distillation process with heat recovery by using a commercial process simulator Aspen Plus® ver. 8.6. We also evaluated its capital and operating costs of the process with Aspen Process Economic Analyzer® ver. 8.4 and literature data. Results show primary energy consumption of the base case was 46.24 kW when 99.75% of hexane was separated from the feed that consists of hexane 330.15 kg/h and lipid (tripalmitin, C51H98O6) 11.30 kg/h. In MVR and SHR models, the primary energy consumption can be reduced to 20.91 and 19.70 kW by enhancing heat recovery of the heat of the separated hexane vapor at the optimum split ratio of the feed stream and compressor discharge pressure. It was found the capital cost of compressor was much higher than that of other units. The utility cost slightly decreased in MVR and SHR models compared with the base case model. Total oil-production cost was in base case was 1.50×103 JPY/kg-oil and that in MVR and SHR models increased to 1.99×103 and 2.51×103 JPY/kg-oil, respectively. By 10 times scale up of this process, the total oil-production cost can be reduced to 178, 217 and 270 JPY/kg-oil in base case, MVR and SHR models, respectively because of insignificant increase in capital cost, General and Administrative (G and A) expense, and maintenance expense by the scale up.
Integrating basic research and technology into business is a critical factor in corporate competitive strategy. It has been proposed to describe problems in the research and development of companies, and the “Boost Gate (hereafter BG)” method as a method to overcome them. It is suggested that the use of this method leads to invigorated fundamental research activities within corporate R&D. Existing research on BG has provided certain details on the type of advice provided at each gate. Yet, these details have not provided methods for handling promising topics that still did not meet decision criteria, including whether to revert these topics or clear them to the next gate after advice is provided. Further, there are limited cases available for reference wherein BG has been implemented. This paper outlines the advising method for topics that do not meet a gate’s decision criteria in BG. It also provides a reference for leveraging BG in corporate R&D by presenting an actual implementation case of that method.
Although numerous official development assistance (ODA) projects have been conducted, some cannot sustain and do not create value, especially when tackling social issues with many stakeholders. To improve this situation, by applying the Project and Program Management (P2M) theory, this paper examines important factors for profiling and implementing ODA programs/projects using case studies in Vietnam, and suggests the necessity for program basis stakeholder management and an approach for sustainable value creation.
The internet of things (IoT) has accelerated the attempts to strengthen Japan’s domestic manufacturing industry. The same is true of the chemical engineering industry. To fully exploit the IoT, which facilitates a rapid and flexible response to changes in markets and technologies, it is important to achieve both trans-organization and trans-industry cooperation. To take advantage of the IoT in the chemical engineering industry, this paper proposes an agile program management model.