A simulator for internally heat integrated distillation columns (HIDiC) with a rate-based model was developed. Using a mass transfer correlation for structured packings and the Chilton-Colburn analogy, heat transfer coefficients for the liquid phase were obtained. Based on the simulation results, the overall heat transfer coefficient U for the internal heat exchange in the HIDiC was estimated. Since the overall heat transfer coefficient obtained was similar to that obtained from the small experimental plant, the simulation with the rate-based model is useful to predict the overall heat transfer coefficient with the mass transfer correlation.
Metal phosphides, including Ni2P, MoP, WP, and CoP, are novel active hydrotreating catalysts with high potential as high-performance catalysts due to their higher hydrogenation activity, which is essential in the hydrodesulfurization of bulky sulfur-containing molecules and in hydrodenitrogenation, compared to conventional Mo- and W-based metal sulfide catalysts. However, the preparation of metal phosphides is more challenging than that of metal sulfides. In the present study, three preparation methods, including in-situ reduction, H2-plasma reduction, and sulfidation-reduction, are introduced, and the effects of preparation conditions on the structure and catalytic performances in hydrodesulfurization are briefly discussed. In addition, H2S passivation is compared with O2 passivation for the preparation of Ni2P catalysts.
Highly active diesel oxidation catalyst for the oxidation of diesel hydrocarbons, with minimal use of platinum group metals, was developed. Pt/Al2O3 showed the highest activity for total oxidation of a mixture of n-decane and 1-methylnaphthalene as model fuel-originated hydrocarbons even after high temperature aging at 750 °C for 5 h in air. The surface density of acid sites on Al2O3 was found to be important to stabilize the Pt surface in the active metallic state, resulting in high hydrocarbon oxidation activity. The catalytic activity of Pt/Al2O3 was strongly dependent on the Pt dispersion. Based on the findings of in-situ FT-IR spectroscopy, a reaction mechanism was proposed, in which acrylate species as reaction intermediate formed on Pt migrates to the acid-base centers of the Al2O3 surface and then reacts with O2 to form CO2. On the basis of these findings, we successfully developed highly active diesel oxidation catalyst by the addition of Pd with Pt/Pd weight ratio of 3/1 and the use of Al2O3 support modified with acidic additives such as WO3.
Low-temperature CO oxidation mechanisms were investigated for size-selected Au nanoparticle catalyst and water-treated Pt/FeOx–Al2O3 catalyst. Both catalysts had high CO oxidation activity even below room temperature. Interestingly, CO oxidations over these catalysts involved important contributions from the metal–oxide interface. For the Au catalyst system, the effects of heat-treatment in air and H2/Ar were investigated on Au/titania-coated silica aerogel catalysts prepared through adsorption of size-selected thiol-capped Au nanoparticles (AuNPs). Change in the form of sulfuric compound lead to a step-wise change in catalytic activity without affecting activation energy, which was observed for both active (<D>Au = 2 nm) and inactive (<D>Au = 4.9 nm) catalysts. These observations strongly indicate that the Au-titania interfaces function as reaction sites in low temperature CO oxidation over a wide Au size range. For the Pt catalyst system, Pt/Fe-containing alumina catalysts treated with water could catalyze CO oxidation with a very low activation barrier (9.2 kJ/mol). Pt nanoparticles and iron oxides formed efficient contacts in the catalysts, probably because of the enhanced mobility of Pt species induced by water treatment. Active oxygen is probably generated at the Pt–FeOx boundary, synchronized with the Fe redox reaction.
In the last two decades, the level of investigation into low salinity water (LSW) flooding has sharply increased. LSW with adequate composition and salinity is injected into the reservoir, which changes the properties of the reservoir rock, thus improving oil recovery. However, for certain reservoirs there might be no improvement at all. This has led for further studies on what exactly governs the lack of improvement upon LSW injection in different reservoirs. Focus was placed on acidic and basic components present in crude oil. They are characterized by measuring total acid number (TAN) and total base number (TBN). This study investigates the wettability alteration of Berea sandstone rock with different crude oil acid and base numbers at specific LSW concentrations and compositions. For this purpose, the sessile drop method was used in specified times. Moreover, the experiments were conducted in two stages, which included crude oil A and B. The experimental results revealed that a significant change in wettability was experienced by the LSW composition of cations K+ and Na+ for the crude oil composition with lower acid number.
The counter diffusion method is a promising approach for the preparation of zeolitic imidazolate framework-8 (ZIF-8) membranes for propylene/propane separation. The effects of the reaction temperature on the structure and permeation properties of ZIF-8 membranes were evaluated to explore the mechanism of membrane formation. ZIF-8 membranes were prepared by the counter diffusion method using dimethylformamide as a solvent in order to control the reaction temperature within the range 25-125 °C. The ZIF-8 formation reaction and interdiffusion of the solutes are facilitated at higher reaction temperatures; the opposing effects of these factors strongly influence the membrane structure and permeation properties. The thickness of the ZIF-8 layer formed in the outermost section of the resultant ZIF-8 membranes decreased from 70 to 40 μm and was characterized by a definite layer structures with increasing reaction temperature. A propylene permeance of 2.2 × 10−9 mol m−2 s−1 Pa−1 with a propylene propane selectivity of around 10 was obtained in the binary gas permeation analysis of the ZIF-8 membrane prepared at 100 °C. The structure of the membranes and the effect of the total feed pressure, propylene fraction in the feed, and temperature dependence on the binary permeation properties were thoroughly characterized.
In this study, two types of plants based natural cationic surfactants, named Mulberry and Henna are introduced and the application of these natural surfactants in wettability alteration of reservoir rock and reducing the interfacial tension of water-oil system is investigated. For this purpose, two natural-based surfactants were extracted from the leaves of the trees of addressed plants and then the interfacial tension (IFT) values between oil and natural surfactant solution and also the contact angle values between natural surfactant solution and rock sample were measured. The results demonstrated that Mulberry extract was able to lower the interfacial tension between oil and distilled water from 43.9 to 4.01 mN/m, while Henna extract could reduce the IFT from 43.9 to 3.05 mN/m. These natural surfactants were also able to reduce the contact angle of rock/fluid system which shows the wettability is altering to water wet system and so it may increase recovery factor by reducing residual oil saturation and Henna extract could reduce the contact angle more than that of Mulberry leaf extract. According to these results in addition to the low price of generating natural surfactants, the feasibility of using these kinds of surfactants in future oil recovery processes is of major concern.
For utilization of kelp, which is produced abundantly in Japan, recovery of mannitol is important because mannitol is a main component of kelp. Mannitol can be recovered into liquid phase by hydrothermal pretreatment of kelp, but when treatment condition is too severe, decomposition of the product mannitol also takes place. To determine the optimum condition for hydrothermal pretreatment, determination of mannitol decomposition rate is indispensable. The purpose of this study is to determine decomposition rate parameters of mannitol under hydrothermal conditions for mannitol recovery from kelp without concomitant decomposition. The decomposition rate was successfully determined using a flow reactor, and the rate constant was expressed with a first-order Arrhenius rate equation with a pre-exponential factor of 3.23 s−1 and activation energy of 26.5 kJ/mol. The obtained reaction rate predicted the behavior of mannitol during hydrothermal pretreatment of kelp with average error of 4.6 %.