Total hydrogenation of furfural and 5-hydroxymethylfurfural (HMF), both of which are important platform chemicals from biomass, produces tetrahydrofurfuryl alcohol (THFA) and 2,5-bis(hydroxymethyl)tetrahydrofuran (BHTHF), respectively, and these products can be used as solvent or raw material of resin. Ni catalysts can give good yields in these reactions; however the low activity and stability are problems. Supported monometallic Pd and Ru catalysts have been reported to be also active in hydrogenation, although the selectivity for total hydrogenation tends to be lower. Other monometallic catalysts such as Cu and Pt generally have low activity in furan ring hydrogenation of furfuryl alcohol (FOL) and 2,5-bis(hydroxymethyl)furan intermediates. We explored various multicomponent catalysts and found that Ni–Pd/SiO2, Pd–Ir/SiO2 and Rh–Ir–ReOx/SiO2 give good yield of THFA or BHTHF with much higher activity than the mixture of each component supported on SiO2.
Photocatalytic water splitting is a potential next generation hydrogen production process which can directly convert light energy to chemical energy without greenhouse gas emission. The effects of dye-modification on the water splitting activity of inorganic semiconductor photocatalysts were investigated to utilize visible light energy for solar energy conversion. The photocatalytic activities of metal oxides, sulfides, oxysulfides, and oxynitrides were improved by dye-modification, because the charge recombination of photogenerated electrons and holes in inorganic semiconductors was effectively suppressed. The charge transfer mechanism of the dye-modified photocatalyst is a two-step excitation process, which is similar to that of photosynthesis. This study revealed that dye-modification is a very effective method to enhance the photoabsorption of visible light and improve the water splitting activity of inorganic semiconductor photocatalysts.
Killing pills of high strength composite hydrogel were prepared by polyacrylamide, chromium acetate crosslinker and silica nanoparticles reinforcer. The killing performance of composite hydrogel depended on its viscoelasticity and compression strength, which were both influenced by polymer content, ratio of polymer to chromium acetate and nano silica content. In this work, the effect of these altering factors on strength of composite hydrogel were evaluated, results showed that elastic moduli (G′), viscous moduli (G″) and compression strength all increased as polymer content increased, ascribing to close entanglement among polymer chains and increasing crosslinking density. G′ was proportional to the ratio of polymer to chromium acetate, whereas G″ and compression strength experienced initial increase then decrease, indicating an optimal ratio existed to achieve the strength peak of composite hydrogel. Silica nanoparticles contributed significantly to viscoelasticity and compression strength of hydrogel. From SEM images, we can see silica nanoparticles attached onto network branches and filled into the network pores in aggregation, in this dispersion form to strengthen the microstructure further to enhance the strength of composite hydrogel. Moreover, the polymer/nmSiO2 composite system is shear-thinning fluid, which promises its pumpability as killing fluid during killing operation.
Predictive methodology was developed for water-hydrocarbon systems under high temperature and pressure conditions based on reported phase equilibrium data using the Peng-Robinson equation of state (EOS) for vapor-liquid equilibrium (VLE) and liquid-liquid equilibrium (LLE). The available experimental data for hydrocarbons with low molecular weight and interaction parameter, kij, with/without a size parameter, lij, included in the Peng-Robinson EOS were fitted to experimental data and accumulated for constructing a predictive equation for hydrocarbons with high molecular weight. As a result, lij was found to be negligible for VLE in water-hydrocarbon systems, and only the fitting parameter kij was necessary in some hydrocarbon and water systems. Consequently, prediction of VLE diagrams was possible using the estimated kij in the Peng-Robinson EOS for water-hydrocarbon systems under high temperature and pressure conditions.
The gasification characteristics of aminobutyric acid and serine were determined under supercritical water conditions using a tubular flow reactor. A 1.0 wt% aqueous solution of these two amino acids was gasified at temperatures ranging from 400 to 650 °C and a pressure of 25 MPa with residence time of 86-222 s. The products were identified and quantified by gas chromatography, and the total organic carbon in the aqueous phase was also determined. The gasification characteristics were compared with those of glycine and alanine. The carbon gasification efficiency increased with higher reaction temperature. The gasification rate followed first order kinetics and was explained well by the Arrhenius equation. The gasification rate of aminobutyric acid was similar to that of glycine and alanine but the gasification rate of serine is faster. The oxygen in the hydroxyl group of serine is highly electronegative, so serine is more reactive than glycine and alanine.
The value of information (VOI) analysis has been recognized as a useful tool for measuring how much the expected monetary value can be increased as a result of an information-gathering activity. The VOI analysis is usually applied in the context of decision making under geological uncertainty, where only a relatively small number of decision alternatives are taken into account. In this paper we discuss possible applications of the VOI analysis in optimization of reservoir development under geological uncertainty. More precisely, by means of the VOI analysis, we evaluate how much an information-gathering activity provides an increase of the maximized expected monetary value, where the maximization is considered in a probabilistic sense to account for geological uncertainty. In this application we often need to deal with a quite large or even infinite number of candidate solutions within an optimization problem, which may cause trouble for an efficient implementation of the VOI analysis. After introducing a general methodology to estimate the VOI in our context, we validate our methodology through a toy problem, and moreover apply to a simple waterflooding problem. We find out that the VOI analysis can be conducted efficiently even in optimization under geological uncertainty by specializing our methodology properly.
Dehydrogenation of formic acid using half-sandwich iridium complexes with bidentate nitrogen ligands has high potential for hydrogen production, because hydrogen is formed in water without organic additive under mild reaction conditions with no CO contamination. Formic acid can be produced by hydrogenation of CO2, and therefore formic acid as hydrogen carrier leads to CO2 utilization. A series of complexes containing various diazole (imidazole and pyrazole) moieties as ligands were comprehensively evaluated as catalysts for the dehydrogenation of formic acid in water. Complexes with bidiazole without any substituent outperformed the complexes with dihydroxylbipyridine reported previously. Introduction of a methyl group as an electron-donating substituent into the diazole moiety enhanced the catalytic activity. The catalyst properties for practical use were also investigated. Simple biimidazole complexes retained their activity for at least one week at 70 °C in a concentrated formic acid solution. Moreover, the complex with 4,4’-biimidazole mixed with FA in a closed vessel produced high-pressure gas without significant decrease of catalytic activity, in comparison with the same reaction under atmospheric pressure. The diazole moiety on the ligand enables effective hydrogen production and is a promising basic ligand structure.
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