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51.
Muhammad Nor Omar Humphrey A. Moynihan Richard J. Hamilton 《European Journal of Lipid Science and Technology》2003,105(1):43-44
The asymmetric Sharpless epoxidation of methyl 13S‐hydroxy‐9Z, 11E‐octadeca‐dienoate (13S‐HODE, 1 ) with tert‐butyl hydroperoxide (TBHP) catalysed by titanium tetraisopropoxide {Ti(iOPr)4} in the presence of L(+)‐diisopropyl tartrate (L‐DIPT) gave methyl 13S‐hydroxy‐11S, 12S‐epoxy‐9Z‐octadecenoate 2 (erythro isomer) in 84% diastereomeric excess (de). The epoxidation of 1 with TBHP catalysed by Ti(iOPr)4 in the presence of D(‐)‐DIPT yielded methyl 13S‐hydroxy‐11RR12R‐epoxy‐9Z‐octadecenoate (threo isomer) 3 in 76% de. 相似文献
52.
Polyvinyl alcohol (PVA) is a synthetic commercial polymer with the inherent hydrophilicity, thermal and chemical resistance, ecofriendly, and a high anti-fouling potential making it an attractive choice for water treatment applications, but has been less studied for oil and gas industry applications. On the other hands, nowadays nanotechnology has gained an important space within most core areas in upstream oil and gas operations. The present work, first PVA at various concentrations, was added to 5 wt% NaCl solution and then, crosslinked by formaldehyde 37% at two different concentration ratios. To compare, a nanocomposite hydrogel was fabricated in the same way with 1 wt% silica nanoparticles (NPs). Contact angle and filtration test were performed to confirm the ability of PVA hydrogel and nanocomposite hydrogel for oil and water adsorption. Following this, a rheology measurement was made to realize the gelation time of samples and their performance for water shutoff applications. Finally, an experimental flooding setup was designed to inject the fluids into carbonate plugs in order to estimate of oil and water effective permeability, and oil recovery factor (RF) before and after the PVA hydrogel and nanocomposite hydrogel injection. Both samples wettability tests showed a super-hydrophilic state for brine droplets and neutral state for synthetic oil droplets by using nanocomposite hydrogel. The flooding tests revealed that the PVA hydrogel was clogged the plug with blocking efficiency of 32.83% for water effective permeability and 14.60% for oil effective permeability. This value was calculated to be 50.37% for water effective permeability and 31.36% for oil effective permeability in the case of nanocomposite hydrogel injection. Oil RF was also reported to be 64.58% after injecting PVA hydrogel which was higher than nanocomposite hydrogel injection with RF of 52.08%. 相似文献
53.
Isabel Martínez Ramon Murillo Gemma Grasa Jose R. Fernández Juan Carlos Abanades 《American Institute of Chemical Engineers》2013,59(8):2780-2794
The integration in a natural gas combined cycle (NGCC) of a novel process for H2 production using a chemical Ca–Cu loop was proposed. This process is based on the sorption‐enhanced reforming process for H2 production from natural gas with a CaO/CaCO3 chemical loop, but including a second Cu/CuO loop to regenerate the Ca‐sorbent. An integration of this system into a NGCC was proposed and a full process simulation exercise of different cases was carried out. Optimizing the operating conditions in the Ca–Cu looping process, 8.1% points of efficiency penalty with respect to a state‐of‐the‐art NGCC are obtained with a CO2 capture efficiency of 90%. It was demonstrated that the new process can yield power generation efficiencies as high as any other emerging and commercial concepts for power generation from NGCC with CO2 capture, but maintaining competing advantages of process simplification and compact pressurized reactor design inherent to the Ca–Cu looping system. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2780–2794, 2013 相似文献
54.
Altaf H. Basta Omar El-Hadi Camilia El-Dewiny 《Polymer-Plastics Technology and Engineering》2013,52(11):1074-1080
The use of rice straw waste (RS) as a substrate for the preparation of metal adsorbents hydrogels has been demonstrated. Four types of RS-based hydrogels were prepared, and evaluated for their effectiveness on purification of wastewater loaded with Cu(II), Fe(II), Zn(II) and Mn(II). Freundlich and Langmuir adsorption equations were used for estimating the adsorption capacities. The results indicated that the hydrogels have significant effect on removing the metal ions from wastewater. The removal efficiency exceeded 95% for Cu(II) and Mn (II) ions and 85 for Fe (II) and Zn (II) ions. 相似文献
55.
Ockwig NW Delgado-Friedrichs O O'Keeffe M Yaghi OM 《Accounts of chemical research》2005,38(3):176-182
The structures of all 1127 three-periodic extended metal-organic frameworks (MOFs) reported in the Cambridge Structure Database have been analyzed, and their underlying topology has been determined. It is remarkable that among the almost infinite number of net topologies that are available for MOFs to adopt, only a handful of nets are actually observed. The discovery of this inversion between expected and observed nets led us to deduce a system of classification "taxonomy" for interpreting and rationalizing known MOF structures, as well as those that will be made in future. The origin of this inversion is attributed to the different modes with which MOF synthesis has been approached. Specifically, three levels of complexity are defined that embody rules "grammar" for the design of MOFs and other extended structures. This system accounts for the present proliferation of MOF structures of high symmetry nets, but more importantly, it provides the basis for designing a building block that "codes" for a specific structure and, indeed, only that structure. 相似文献
56.
Grigori M. Sisoev Omar K. Matar Christopher J. Lawrence 《Chemical engineering science》2005,60(3):827-838
In this work, we present results of a study of gas absorption into a falling film on a vertical substrate. The film flow is accompanied by the formation of nonlinear waves which strongly influence the diffusion layer that develops from the film surface. As a result, significant enhancement of mass transfer has been observed in experiments. We use recent advances in modelling of the hydrodynamics and solve a two-dimensional convective-diffusion equation for the solute concentration. Numerical solutions for the finite-amplitude wave regimes and associated integral absorption rates are obtained for a range of flow conditions. Our results show clearly the influence of waves on the development of the diffusion layer and, in particular, the enhancement of absorption due to the waves; the existence of optimal conditions for maximizing the absorption rate is also demonstrated. 相似文献
57.
María Dolores López‐Ramírez Ulises Miguel García‐Ventura Fabricio Omar Barroso‐Muñoz Juan Gabriel Segovia‐Hernández Salvador Hernández 《化学工程与技术》2016,39(2):271-275
The esterification of oleic acid and methanol using sulfuric acid as a homogeneous catalyst is studied in reactive‐separation systems. The conversion of the free fatty acid was investigated in two different experiments with the molar ratio of methanol/oleic acid, amount of catalyst, temperature, and reaction time as variables. The conversion of the free fatty acid was found to depend strongly on the molar ratio of methanol/oleic acid. The reaction time had a direct effect on the conversion of the free fatty acid, and this conversion decreased with higher temperature. These results were valuable for a preliminary study on biodiesel production, using an acid homogeneous catalyst in a reactive dividing‐wall distillation column. 相似文献
58.
Cornelius B. Bavoh Bhajan Lal Omar Nashed Muhammad S. Khan Lau K. Keong Mohd. Azmi Bustam 《中国化学工程学报》2016,24(11):1619-1624
Recently ionic liquids(ILs) are introduced as novel dual function gas hydrate inhibitors. However, no desired gas hydrate inhibition has been reported due to poor IL selection and/or tuning method. Trial error as well as selection based on existing literature are the methods currently employed for selecting and/or tuning ILs. These methods are probabilistic, time consuming, expensive and may not result in selecting high performance ILs for gas hydrate mitigation. In this work, COSMO-RS is considered as a prescreening tool of ILs for gas hydrate mitigation by predicting the hydrogen bonding energies(E_(HB)) of studied IL inhibitors and comparing the predicted E_(HB) to the depression temperature(?) and induction time. Results show that, predicted EHBand chain length of ILs strongly relate and significantly affect the gas hydrate inhibition depression temperature but correlate moderately(R = 0.70) with average induction time in literature. It is deduced from the results that, ? increases with increasing IL EHBand/or decreases with increasing chain length. However, the cation–anion pairing of ILs also affects IL gas hydrate inhibition performance. Furthermore, a visual and better understanding of IL/water behavior for gas hydrate inhibition in terms of hydrogen bond donor and acceptor interaction analysis is also presented by determining the sigma profile and sigma potential of studied IL cations and anions used for gas hydrate mitigation for easy IL selection. 相似文献
59.
Catalysis Letters - Herein, polyphenol oxidase (PPO) was purified from Coleus forskohlii via a three-step process involving precipitation by (NH4)2SO4, ion exchange chromatography and gel... 相似文献
60.
Patrick Ryan Omar K. Farha Linda J. Broadbelt Randall Q. Snurr 《American Institute of Chemical Engineers》2011,57(7):1759-1766
A variety of metal‐organic frameworks (MOFs) with varying linkers, topologies, pore sizes, and metal atoms were screened for xenon/krypton separation using grand canonical Monte Carlo (GCMC) simulations. The results indicate that small pores with strong adsorption sites are desired to preferentially adsorb xenon over krypton in multicomponent adsorption. However, if the pore size is too small, it can significantly limit overall gas uptake, which is undesirable. Based on our simulations, MOF‐505 was identified as a promising material due to its increased xenon selectivity over a wider pressure range compared with other MOFs investigated. © 2010 American Institute of Chemical Engineers AIChE J, 2011 相似文献