Methyl lactate (MLA), a versatile biomass platform, was typically produced from the catalytic conversion of high-priced fructose. High fructose corn syrup (HFCS) is a mixture of glucose, fructose, ...water, etc., which is viewed as an economical substitute for fructose to produce MLA due to the much lower cost of separation and drying processes. However, the transformation of HFCS to MLA is still a challenge due to its complex components and the presence of water. In this work, the catalytic conversion of HFCS to MLA over CoO@silicalite-1 catalyst synthesized via a straightforward post citric acid treatment approach was reported. The maximum MLA yield reached 43.8% at 180 °C for 18 h after optimizing the reaction conditions and Co loading. Interestingly, adding extra 3% water could further increase the MLA yield, implying that our CoO@silicalite-1 catalyst is also capable for upgrading wet HFCS. As a result, the costly drying process of wet HFCS can be avoided. Moreover, the activity of CoO@silicalite-1 catalyst can be regenerated for at least four cycles via facile calcination in air. This study, therefore, will provide a new opportunity to not only solve the HFCS-overproduction issues but also produce value-added MLA.
Adsorption equilibria of CO2, CH4, N2, O2, and Ar were determined on three lab-synthesized ZSM-5 adsorbents and four commercially available high silica zeolites including HiSiv-3000, HSZ-980HOA, ...HSZ-890HOA, and HSZ-390HUA. The synthesized ZSM-5 samples have a similar pore textural property (Brunauer–Emmett–Teller (BET) surface area and pore volume) as that of HiSiv-3000. The BET surface areas and total pore volume of the ZSM-5 sample were found to be ∼300 m2·g–1 and 0.2 cm3·g–1, respectively. The synthesized materials have relatively higher adsorption capacities than those of HiSiv-3000 for the gases studied in this work. The order of adsorption capacities of CO2, CH4, N2, Ar, and O2 on each high silica zeolite follows the order of their polarizabilities. The selectivities of N2/O2 and Ar/O2 pairs are close to 1.0, suggesting that it is very difficult to separate them by equilibrium-based adsorption processes. HSZ-890HOA and synthesized DT-100 showed higher equilibrium selectivities for CO2 over N2 and CH4, implying that they are potential adsorbents for CO2 separation from flue gases as well as landfill gases.
Catalytic transfer hydrogenation (CTH) of biomass-derived furfural (FAL) to furfuryl alcohol is recognized as one of the most versatile techniques for biomass valorization. However, the irreversible ...sintering of metal sites under the high-temperature reaction or during the coke removal regeneration process poses a serious concern. Herein, we present a silicalite-1-confined ultrasmall CuO structure (CuO@silicalite-1) and then compared its catalytic efficiency against conventional surface-supported CuO structure (CuO/silicalite-1) toward CTF of FAL with alcohols. Characterization results revealed that CuO nanoparticles encapsulated within the silicalite-1 matrix are ∼1.3 nm in size in CuO@silicalite-1, exhibiting better dispersion as compared to that in the CuO/silicalite-1. The CuO@silicalite-1, as a result, exhibited nearly 100-fold higher Cu-mass-based activity than the CuO/silicalite-1 counterpart. More importantly, the activity of the CuO@silicalite-1 catalyst can be regenerated via facile calcination to remove the surface-bound carbon deposits, unlike the CuO/silicalite-1 that suffered severe deactivation after use and cannot be effectively regenerated.
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•Ultrasmall CuO NPs are encapsulated in silicalite-1 matrix for CTH of furfural•Encapsulated CuO catalyst shows impressive Cu-mass-based activity of ∼130 hr−1•Carbon deposits can be easily removed without the obvious increase in CuO size•Strong Cu-Si interactions exist in silicalite-1-encapsulated CuO structure
Chemistry; Inorganic chemistry; Chemical reaction; Catalysis; Materials science
Purpose
The behaviors of sea surface drag coefficient should be well understood for an accurate hurricane prediction. The speed of wind has been applied to characterize the spray production; however, ...this could result in inaccurate spray productions compared to the experimental or field data if the influence of wave state is not considered. This paper aims to integrate a new sea spray generation function, described by windsea Reynolds number, into the spray momentum flux formula to calculate the spray momentum.
Design/methodology/approach
On the basis of this spray momentum, this study proposes the new formulas of spray stress and drag coefficient when the wind speed is high.
Findings
Results of the revised formulas show that wave status had significant effects on the spray stress and sea surface drag coefficient. Also, wave age was found to be an important parameter that affects the drag coefficient. The drag coefficient decreased with the increasing wave age. Comparison between this study’s theoretical and observation values of drag coefficient shows that the study results are close to the measured values.
Research limitations/implications
The research findings can enhance the understanding of the behaviors of sea surface drag for an accurate hurricane prediction.
Originality/value
A new sea spray generation function, described by windsea Reynolds number, is integrated into the spray momentum flux formula to calculate the spray momentum. On the basis of this spray momentum, this study proposes the new formulas of spray stress and drag coefficient when the wind speed is high.
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•Polymeric adsorbent with predominant micropores and mesopores.•Demonstration of molecular sieving effect in the polymeric adsorbent.•Adsorption of 2-naphthol, berberine ...hydrochloride, and Congo red.•Effective separation of berberine hydrochloride and 2-naphthol.
A hypercrosslinked poly(styrene-co-divinylbenzene) resin (TEPA) was synthesized and characterized as a specific polymeric adsorbent for concentrating berberine hydrochloride from aqueous solutions. Three organic molecules of different sizes (2-naphthol, berberine hydrochloride, and Congo red) were used as target molecules to elucidate the molecular sieving effect of the TEPA adsorbent. Because the TEPA adsorbent has a pore structure consisting mainly of micropores and mesopores, the adsorption of 2-naphthol from aqueous solutions is very efficient due to the micropore filling effect. The adsorption of berberine hydrochloride mostly takes place in the mesopores as well as macropores, while the adsorption of Congo red mainly occurs in the macropores. The smaller adsorbate molecule (2-naphthol) reaches the adsorption equilibrium much faster than the larger ones (berberine hydrochloride and Congo red). An adsorption breakthrough experiment with an aqueous solution containing 2-naphthol and berberine hydrochloride demonstrated that the TEPA adsorbent could effectively remove 2-naphthol from berberine hydrochloride at 0–107 BV (bed volume, 1 BV=10ml), and the berberine hydrochloride concentration was increased from 66.7% to 99.4%, suggesting that this polymeric adsorbent is promising for purifying berberine hydrochloride and similar alkaloids from herbal plant extracts.
•An on-line sample pretreatment IC system is used to determine Cr(VI).•The method relies on valve-switching technique.•A polymer-based reversed-phase column is used as a pretreatment column.•The ...matrix in Colla corii asini can be eliminated via on-line pretreatment.
An ion chromatography (IC) system with on-line sample pretreatment using valve-switching technique was developed for the determination of hexavalent chromium (Cr(VI)) in Colla corii asini. Colla corii asini is a complicated sample with organics as main matrix. In this work, a polymer-based reversed-phase column was used as a pretreatment column. Via valve-switching technique, sample solution with target ions were eluted from a collection loop to analytical columns, with matrix eliminated on-line. Under the optimized separation conditions, the method showed good linearity (r=0.9998) in the range of 0.004–1.0mg/L and satisfactory repeatability (RSD<3%, n=6). The limit of detection (LOD) was 1.4μg/L (S/N=3). The average spiked recoveries of Cr(VI) were 93.4–102.0%. The result showed that the on-line sample pretreatment IC system was convenient and practical for the determination of trace Cr(VI) in Colla corii asini samples
Four organic Lewis acids, samarium(III), aluminum(III), yttrium(III), and indium(III) trifluoromethanesulfonates were combined with four organic Brønsted acids, benzenesulfonic, toluene-p-sulfonic, ...trichloroacetic, and oxalic acids to synergistically catalyze the decomposition of glucose to produce levulinic acid (LA). The combination of aluminum trifluoro-methanesulfonate (Al(CF3SO3)3) and oxalic acid (H2C2O4) exhibited a strong synergic activity for the decomposition of glucose to LA. The effects of the mole fraction of Al(CF3SO3)3 in the Al(CF3SO3)3-H2C2O4 system on the decompositions of glucose, fructose, and 5-hydroxymethylfurfural (5-HMF) were investigated. The mixed-acid system showed the strongest synergic catalytic activity for glucose, fructose, and 5-HMF decompositions at the Al(CF3SO3)3 mole fraction of 0.33. The effect of temperature on the decomposition of glucose in the Al(CF3SO3)3-H2C2O4 system was also investigated. Based on the results obtained in this contribution and previous work, synergy in catalytic systems was demonstrated.
Transition-metal-catalyzed transfer hydrogenation with an in situ hydrogen donor has received a great deal of attention from both academia and industry as an alternative to the traditional ...high-pressure-hydrogen process, owing to its better efficiency, atom economy, and sustainability features. Hydrogen stored in the chemical bonds of formic acid (FA), a promising hydrogen storage compound that could be derived from biomass or reduction of CO2, can be extracted selectively and used for diverse catalytic transformations. This Review summarizes and compares recent progress in catalytic transfer hydrogenation (CTH) via heterogeneous hydrogen transfer from FA. Transformations of biomass-derived platform chemicals (e.g., aromatic units, C5 and C6 sugars, furans, glycerol, fatty acids, levulinic acid (LA)), nitrogen-containing compounds (e.g., nitroarenes, quinolines), and organochlorinated compounds via transfer hydrogenation, hydrogenolysis, and hydrodechlorination (HDC) are outlined. Synthesis strategies of the heterogeneous metal catalysts (e.g., metal and support type, metal–support interaction, single-atom, alloy effect, and confinement effect) and optimization of the reaction conditions (e.g., temperature, solvents, additives, and FA dosages) for enhancing the catalytic activity and regulating the product distribution are presented. Structure–activity relationships based on both dehydrogenation and hydrogenation of metal catalysts as well as the mechanistic interpretation of CTH with FA are also highlighted. Finally, current challenges and outlook for the future development of the field are discussed.
Under microwave irradiation, 12-tungstophosphoric acid (HPW) could be successfully synthesized in situ and encapsulated in the supercage of ultra stable Y (USY) in several minutes. But the framework ...of USY collapsed easily in traditional hydrothermal synthesis routine.
31P MAS NMR, transmission electron microscopy (HR-TEM), N
2 adsorption, inductively coupled plasma (ICP) and X-ray diffraction (XRD) characterizations found that the formed HPW molecule located separately in the supercage of USY. Temperature-programmed desorption of NH
3 (NH
3-TPD) showed that HPW-USY exhibited stronger acidity than that of pure USY, and adsorbed pyridine infrared (Py-IR) disclosed that the concentration of Brönsted acid sites was enhanced. This hybrid solid acid exhibited higher activity in the synthesis of 4,4′-dimethyldiphenylmethane via toluene and formaldehyde and could be utilized as a solid acid catalyst in aqueous solutions.
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