Cu-based spinel-oxides CuB2O4 (B = Fe, Mn, Cr, Ga, Al, or Fe0.75Mn0.25) were synthesized via a sol-gel method and subsequent solid-state reaction. The spinels mechanically mixed with gamma-Al2O3 were ...evaluated for production of hydrogen from dimethyl ether steam reforming (DME SR). The reduction behavior and crystal property of these spinel-oxides, and the Cu oxidation state in spinel catalysts were investigated by temperature-programmed reduction, X-ray diffraction, and X-ray photoelectron spectroscopy techniques. The reduced phases of the Cu-based spinel catalysts that strongly affected the catalytic activity and durability were composed of metallic copper with metal oxides (MnO (B = Mn), Cr2O3 (B = Cr), and Al2O3 (B = Al)) or with spinels (CuGa2O4 (B = Ga), Fe3O4 (B = Fe), and MnFe2O4 (B = Fe0.75Mn0.25). The stability of B metal oxides and the interaction between copper species and B metal oxides significantly contributed to the reforming performance.
The nanostructured catalysts of copper hydrogen phosphate monohydrate and copper pyrophosphate were developed for catalyzing dehydration of fructose to 5-hydroxymethylfurfural under hot compressed ...water at 200°C. As evidenced by X-ray absorption fine structure, X-ray diffraction, SEM, and TEM analyses, the CuHPO4·H2O (as-synthesized) exhibits needle-like nanocrystals, while the samples calcined at 600°C and 900°C display α-Cu2P2O7 phases in rod-like nanostructure and irregularly shaped microcrystal, respectively. Each copper is distributed throughout the phosphate network. Among all samples, the Cu2P2O7 catalysts with weak acid strength (+3.3≤H0≤+4.8) was highly active and selective for 5-hydroxymethylfurfural production with a yield of 36% and maximum turnover number, while no metal leaching was observed after the reaction.
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► The copper phosphates catalyze dehydration of fructose to 5-hydroxymethylfurfural ► X-ray absorption fine structure, X-ray diffraction, acid–base titration, and TEM ► The CuHPO4.H2O exhibits needle-like nanocrystals. ► The α-Cu2P2O7 are in rod-like nanostructure and irregularly shaped microcrystal. ► No metal leaching was observed after the reaction.
Turning waste glycerol into a fundamental chemical used in the petrochemical industry offers an opportunity to reduce not only waste from biodiesel production but also the consumption of ...petroleum-based chemicals. In the present work, glycerol was converted to 1,3-propanediol over Pt-WO
x
/Al
2
O
3
catalysts, while focusing on the influence of W loading contents (10–20 wt.%) and catalyst pretreatment conditions, specifically the calcination temperatures of WO
x
/Al
2
O
3
(700–900 °C), calcination temperatures of Pt-WO
x
/Al
2
O
3
(350–450 °C) and reduction temperatures of Pt-WO
x
/Al
2
O
3
(300–400 °C). The characteristics of the catalysts were identified by applying N
2
-sorption, XRD, Raman, CO pulse chemisorption, NH
3
-TPD, H
2
-TPR, H
2
-TPD, SEM and TEM-EDS and XPS. The W loading contents and pretreatment conditions strongly affected the activity and products selectivity. The W content and calcination temperature of WO
x
/Al
2
O
3
at 15 wt.% and 800 °C, respectively, were evaluated as the most suitable in providing optimum W-O-W clusters to generate H
δ+
which was a key parameter for the generation of 1,3-propanediol. The calcination and reduction temperatures of Pt-WO
x
/Al
2
O
3
at 400 °C and 350 °C, respectively, were mandatory to sufficiently convert PtCl
2
to Pt
3
O
4
and Pt
3
O
4
to metallic Pt, respectively. The optimized Pt-WO
x
/Al
2
O
3
catalyst achieved a high glycerol conversion (44.7%) with high selectivity toward 1,3-propanediol (45.1%) under a reaction temperature and pressure of 220 °C and 60 bar, respectively.
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► The phosphates of calcium and strontium as the hydrolysis/dehydration catalysts. ► 5-HMF from fructose, glucose, and cellulose conversion under hot compressed water. ► The CaP2O6 ...and α-Sr(PO3)2 have proper acid strength (3.3⩽H0⩽4.8) for the reaction. ► The phosphates provided 5-HMF yields of 34–39% from fructose conversion. ► The total yield of glucose and 5-HMF (34%) from cellulose conversion over α-Sr (PO3)2.
The phosphates of alkaline earth metals (calcium and strontium) synthesized by precipitation process in acetone–water media system were used as catalysts for converting fructose, glucose, and cellulose to 5-hydroxymethylfurfural (HMF) under hot compressed water condition. It was found that the phosphates of calcium and strontium effectively catalyzed the HMF formation from fructose and glucose dehydration and cellulose hydrolysis/dehydration reaction, as compared with the non-catalytic system. The XRD analysis confirmed the CaP2O6 and α-Sr(PO3)2 crystalline phases of the catalyst samples, while acid strength of both catalysts was in a range of +3.3⩽H0⩽+4.8. From the study, CaP2O6 and α-Sr(PO3)2 showed similar catalytic performance toward the dehydration of sugars, providing the HMF yields of 20–21% and 34–39% from glucose and fructose, respectively; whereas the total yield of glucose and HMF from the hydrolysis/dehydration of cellulose over α-Sr(PO3)2 (34%) was higher than that over CaP2O6 (17.4%).
Porous carbon was successfully synthesized from palm male flowers (PMFs), using microwave-assisted potassium hydroxide (KOH) activation and was used as a catalyst support for the conversion of palm ...oil into bio-hydrocarbons, in fractions of green diesel and bio-jet fuel. Palm male flower-derived porous carbon (PC), consolidated with well dispersed cobalt phosphide (CoP) nanoparticles, was synthesized by simple wet-impregnation with subsequent thermal treatment. The physicochemical properties of the synthesized CoP/PC catalysts were evaluated by various techniques including proximate and ultimate elemental analysis, FTIR, XRD, N2 sorption, SEM, TEM–EDS, and NH3-temperature programmed desorption (TPD). The effects of the pyrolysis temperatures (600−900 °C), used for the impregnated samples before the reduction process, on catalyst properties and catalytic performance were investigated. Moreover, the effect of a liquid hourly space velocity of 0.5–1.5 h−1 and reaction temperatures of 340–420 °C was studied in the palm oil conversion. The catalyst pyrolyzed at 600 °C possessed the greatest particle dispersion and surface area, and showed the highest yield of liquid hydrocarbon product (C9–C18). We also found that the high pyrolysis temperature above 800 °C partially transformed the Co2P phase into CoP one which significantly exhibited higher cracking activity and bio-jet selectivity, due to the improved acidity of the catalyst.
Due to their interfacial defects between inorganic fillers and polymer matrices, research into mixed matrix membranes (MMMs) is challenging. In the application of CO2 separation, these defects can ...potentially jeopardize the performance of membranes. In this study, aminosilane functionalization is employed to improve the nano-sized zeolite Y (ZeY) particle dispersion and adhesion in polyether block amide (Pebax). The performance of CO2/CH4 separation of Pebax mixed matrix composite hollow fiber membranes, incorporated with ZeY and aminosilane-modified zeolite Y (Mo-ZeY), is investigated. The addition of the zeolite filler at a small loading at 5 wt.% has a positive impact on both gas permeability and separation factor. Due to the CO2-facilitated transport effect, the performance of MMMs is further improved by the amino-functional groups modified on the ZeY. When 5 wt.% of Mo-ZeY is incorporated, the gas permeability and CO2/CH4 separation factor of the Pebax membrane are enhanced by over 100% and 35%, respectively.
The increasing rate of oil and gas production has contributed to a release of oil/water emulsion or mixtures to the environment, becoming a pressing issue. At the same time, pollution of the toxic ...cigarette butt has also become a growing concern. This study explored utilization of cigarette butt waste as a source of cellulose acetate-based (CA) polymer to develop a phase inverted membrane for treatment of oil/water emulsion and compare it with commercial polyvinylidene difluoride (PVDF) and polysulfone (PSF). Results show that the CA-based membrane from waste cigarette butt offers an eco-friendly material without compromising the separation efficiency, with a pore size range suitable for oil/water emulsion filtration with the rejection of >94.0%. The CA membrane poses good structural property similar to the established PVDF and PSF membranes with equally asymmetric morphology. It also poses hydrophilicity properties with a contact angle of 74.5°, lower than both PVDF and PSF membranes. The pore size of CA demonstrates that the CA is within the microfiltration range with a mean flow pore size of 0.17 µm. The developed CA membrane shows a promising oil/water emulsion permeability of 180 L m−2 h−1 bar−1 after five filtration cycles. However, it still suffers a high degree of irreversible fouling (>90.0%), suggesting potential future improvements in terms of membrane fouling management. Overall, this study demonstrates a sustainable approach to addressing oil/water emulsion pollution treated CA membrane from cigarette butt waste.
The durability of composite catalysts of CuFe
2O
4 and
γ-Al
2O
3 was investigated during steam reforming (SR) of dimethyl ether (DME). Partial degradation of the composites proceeded due to the ...concomitant effect of copper sintering and carbon formation. The catalyst degraded after SR for 1100 h was regenerated by calcination in air in the temperature range of 500–700 °C; redispersion of copper via spinel formation and simultaneous carbon burning were achieved. The apparent activation energy for DME SR over the catalyst was estimated to be in the range of 150–160 kJ mol
−1 and remained almost stable during the DME SR reaction test for 1100 h. Degradation of the catalyst was found to follow first-order kinetics with a deactivation rate constant of
0.95
×
10
−3
h
−1
.
Membrane distillation (MD) is an attractive technology for desalination, mainly because its performance that is almost independent of feed solute concentration as opposed to the reverse osmosis ...process. However, its widespread application is still limited by the low water flux, low wetting resistance and high scaling vulnerability. This study focuses on addressing those limitations by developing a novel corrugated polyvinylidene difluoride (PVDF) membrane via an improved imprinting technique for MD. Corrugations on the membrane surface are designed to offer an effective surface area and at the same time act as a turbulence promoter to induce hydrodynamic by reducing temperature polarization. Results show that imprinting of spacer could help to induce surface corrugation. Pore defect could be minimized by employing a dual layer membrane. In short term run experiment, the corrugated membrane shows a flux of 23.1 Lm
h
and a salt rejection of >99%, higher than the referenced flat membrane (flux of 18.0 Lm
h
and similar rejection). The flux advantage can be ascribed by the larger effective surface area of the membrane coupled with larger pore size. The flux advantage could be maintained in the long-term operation of 50 h at a value of 8.6 Lm
h
. However, the flux performance slightly deteriorates over time mainly due to wetting and scaling. An attempt to overcome this limitation should be a focus of the future study, especially by exploring the role of cross-flow velocity in combination with the corrugated surface in inducing local mixing and enhancing system performance.
Ethylene, a plant hormone, is a gas that plays a crucial role in fruit ripening and senescence. In this work, a novel ethylene scavenger was prepared from amorphous silica–alumina derived from sugar ...cane bagasse ash (SC-ASA) and used to prolong the shelf life of mango fruits during storage. KMnO4 at 2, 4, or 6 wt %/w was loaded on SC-ASA using an impregnation method. The results showed that 4% w/w KMnO4 loaded on SC-ASA (4KM/SC-ASA) was superior for ethylene removal at an initial ethylene concentration of 400 μL L–1 for 120 min under ambient conditions (25–27 °C and 70–75% relative humidity), resulting in 100% ethylene removal. The kinetic study of ethylene removal showed that the adsorption data were best fitted with a pseudo-first-order kinetic model. The effects of 4KM/SC-ASA as sachets on the quality changes of the mango fruits were investigated, with the results showing that mango fruits packed in cardboard boxes with 4KM/SC-ASA had significantly delayed ripening, low levels of ethylene production, respiration, and weight loss, high fruit firmness, low total soluble solids, and high acidity compared to those of the control treatment. These findings should contribute to developing an ethylene scavenger to extend the shelf life of fruits, reduce the waste of the sugar and ethanol industries, and make it a valuable material.
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