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•Transition metal oxide (TMO) on zeolite Y able to produce green diesel via deoxygenation.•The deoxygenation conducted without H2 and solvent.•Ni-Y show highest deoxygenation activity ...and product selectivity.•Ni-Y still maintains high deoxygenation activity after four consecutive runs.
H2-free deoxygenation is a very important process in producing high-quality biofuel without the use of H2 gas supply. Considering the costly price of the noble metals, transition metal (TM) based catalysts are more affordable, and the performance is comparable to the noble metal-based catalyst. In this study, TMO supported on zeolite Y catalysts (Ni-, Cu-, Co-, Zn- and Mn-Y) are prepared via wet-impregnation for deoxygenation of triolein, a model compound of non-edible oil under H2-free condition. The deoxygenation activity of TMO supported on zeolite Y is following the order of Ni-Y > Co-Y > Cu-Y > Mn-Y > Zn-Y. The nickel oxide supported on zeolite-Y (Ni-Y) shows the highest conversion up to 76.21 % with 84.28 % hydrocarbon selectivity after reacted at 380 °C for 2 h. Besides, the selectivity toward diesel range hydrocarbon is 92.61 %. The superior deoxygenation activity of Ni-Y can be related to synergistic effect between the reduced B/L and high hydrogenolysis ability of Ni that promote the decarboxylation reaction, suppress the cracking and polymerization of heavy hydrocarbon. Therefore, Ni-Y is a potential catalyst to obtain high quality green diesel from non-edible oil through catalytic deoxygenation without addition of external H2 source.
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•Mild dual-alkali treatment greatly enhanced the fast toluene adsorption of Y-ZLSP.•Y-ZLSP-NT(1/1) had a high qb of 112.1 mg/g for toluene in dynamic adsorption.•Controllable pore ...evolution and enriched functional groups contributed to the high adsorption capacity.•Y-ZLSP-NT(1/1) had good regenerability and robustness for toluene adsorption.
In this study, the dual-alkali treatment of the Y-ZLSP zeolite recycled from lithium-silicon powder (LSP) waste for enhanced adsorption removal of low-concentration toluene was systematically studied. The results revealed that a mild condition dual-alkali treatment of Y-ZLSP significantly improved its toluene adsorption performance, as well the regenerability and robustness. The Y-ZLSP-NT(1/1) that was obtained under the conditions of NaOH and TPAOH molar ratio at 1/1, total concentration of 0.0050 M, and treated at 55 °C for 0.5 h showed the best adsorption property, with a saturated adsorption capacity (qs) of 139.7 mg/g at 1000 mg/m3 inlet concentration. Importantly, it had an up to 112.1 mg/g high of breakthrough adsorption capacity (qb). Toluene adsorption on Y-ZLSP-NT(1/1) was governed by physical adsorption, primarily due to pore filling and hydrogen bonding. The dual-alkali treatment resulted in a controllable pore evolution and greatly enriched the surface acid functional groups of Y-ZLSP. The evolved microporosity provided more adsorption sites, the mesoporosity afforded mass transfer channels. The toluene adsorption on Y-ZLSP-NT(1/1) follows a pseudo-first-order model and is typically an entropy-driven exothermic process with ΔH, ΔG and ΔS of −1.98 kJ/mol, −8.29 kJ/mol and 34.50 J/(mol·K), respectively.
The development of new technologies that employ greenhouse gases, such as CO2 and CH4, is becoming more important in the fight against global warming. Catalytic methane dry reforming (MDR) is one ...straightforward way to reduce CO2 and CH4. In this study, the influence of nickel (Ni) loading on the catalytic performance of fibrous zeolite-Y catalysts (Ni/FHY) for MDR was explored. The study involved the synthesis and testing of Ni/FHY with varying Ni loadings (1 wt% to 10 wt%). The results demonstrate that the metal loading significantly affects the catalysts' performance through metal-support interaction. The catalytic activity showed that the performance of FHY increased with optimum metal loading of 5 wt% where the CO2 conversion increased to 90.3% from 82.2%, and CH4 conversion to 94.2% from 79.6%. The findings suggest that the 5 wt% optimal Ni loading showed the critical role of the metal-support interaction in shaping catalytic properties. Hence, this work provides insights into catalyst optimization for sustainable industrial processes, highlights the importance of the synergistic metal-support interaction, and provides insights into the relationship between Ni content and catalytic behavior. Thus, it offers a basis for optimizing catalysts in MDR and contributes to the advancement of sustainable industrial processes.
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•Methane dry reforming is highly influenced by Ni loadings (1-10 wt.%) onto FHY.•Different Ni loading onto FHY affects NiO dispersion and metal-support interaction.•5Ni/FHY: Optimal interaction, homogenous NiO dispersion, and minimal coke formation.•10Ni/FHY: NiO agglomeration, poor NiO dispersion, and high coke formation.
In this work, a study of the interzeolite transformation from a parent zeolite Y (FAU topology) into zeolite ZSM-5 (MFI topology) was carried out, without using organic structure directing agents, by ...addition of SiO2 to adjust the composition of the starting gel. Depending on the SiO2/Al2O3 molar ratio, zeolite Y can be present in amounts equivalent to those of seed-assisted syntheses. Zeolite Y was successfully transformed in ZSM-5, but a rigorous control of OH−/SiO2 and Na+/SiO2 molar ratios is necessary to avoid incomplete transformation and/or contamination by layered silicates, such as magadiite and kenyaite. For hydrothermal treatment duration lesser than 12 h, the phase dissolution of the Y zeolite is observed, resulting in amorphous phase after 24 h. From 48 h, nucleation and growth of ZSM-5 crystals, with increasing crystallinity up to 120 h, is observed. During the interzeolite transformation, FTIR spectra show the disappearance of the band at 568 cm−1 and the appearance of a band at 545 cm−1, assigned to the 5-membered double rings of ZSM-5. Scanning electron microscopy images suggest that the crystallites of zeolite Y condense and absorb silicate species from solution to form larger aggregates of ZSM-5 zeolite. These structural and morphological changes are accompanied by textural changes detected in nitrogen adsorption isotherms. These results suggested that a combined solution mediated and solid-state transformation mechanism is probably occurring. Since these zeolites do not possess any other structural features in common, RBU approach seems to be more adequate to describe this specific interzeolite transformation.
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•ZSM-5 was prepared by interzeolite transformation from zeolite Y without OSDAs.•Addition of SiO2 is necessary to have an adequate SiO2/Al2O3 molar ratio.•A rigorous control of Na+/SiO2 and OH−/SiO2 is needed to observe pure ZSM-5 phase.•The mechanism seems to occur by a combined solution and solid-state processes.•The RBU approach is more suitable to this specific interzeolite transformation.
In the current study, mesoporous MnO2@Zeolite-Y (MOZ) was synthesized using the ultrasonic method. Then, MOZ was utilized to enhance the electrochemical behavior of poly ortho-aminophenol (POAP) ...conducting polymer. The POAP/MnO2@Zeolite-Y (MOZ/POAP) composite was synthesized by electropolymerization over the zeolite-modified working electrode surface. To investigate and compare the electrochemical behavior of the synthesized materials, two electrodes of MOZ and MOZ/POAP were designed. Subsequently, the electrochemical characteristics of the two mentioned electroactive compounds were evaluated by galvanostatic charge/discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) tests in a three-electrode setup. The comparison of the results revealed that the MOZ/POAP electrode had a more significant performance and recorded a specific capacitance (Cs) of 422 F g−1 at 1 A g−1 and cyclic stability of 97.2 % over 10,000 cycles. After verifying this electrode's remarkable efficacy, a symmetric supercapacitor of MOZ/POAP was designed and analyzed by CV and GCD techniques in a two-electrode system. This electrode revealed a Cs of 184 F g−1 at 1 A g−1, energy density of 12.02 Wh kg−1, power density of 275 W kg−1, and cyclic stability of 95.7 % over 10,000 cycles. This impressive performance was due to the presence of the manganese metal in MOZ and nitrogen and oxygen species of POAP in improving the pseudocapacitance behavior, POAP as a conductive chemical and mesoporous zeolite-Y for enhancing the electrical double-layer behavior of the electrode by providing a medium for electrochemical reactions.
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•Acid site density of HY influences the guaiacol conversion and product distribution.•Presence of acetic acid and cyclopentanone did not affect the conversion of guaiacol.•Furfural ...reduced the guaiacol conversion and selectivity to deoxygenated products.•Ring-opening of furan is a crucial step in the conversion of furfural for effective HDO.•Experimental observations are aligned with adsorption energy calculations using DFT.
In this study, a systematic analysis of the effect of three biomass pyrolysis oxygenates, viz., acetic acid, cyclopentanone and furfural, on the hydrodeoxygenation (HDO) of guaiacol is performed. Bifunctional Pt/HY catalysts with different Si/Al ratios were screened for the HDO of guaiacol. Guaiacol conversion and the cyclohexane yield increased with the concentration of acid sites in the zeolites. The presence of acetic acid and cyclopentanone did not affect the guaiacol conversion and the product selectivity, while guaiacol conversion decreased significantly in the presence of furfural. The effects of temperature, reaction time, and the guaiacol-furfural molar ratio on the HDO of guaiacol were studied. The time evolution of products showed that the furan ring opening influences the conversion of guaiacol.Quantum chemicaldensity functional theorycalculations using individual and binary model compounds revealed the decrease in adsorption energy of guaiacol over Pt (111) in the presence of furfural.
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•Nanocomposites of zeolite Y with metal oxide were successfully synthesized via a procedure comprising.•Nanocomposites based zeolite Y have shown to be excellent candidates for ...desulfurization of diesel.•Optimum condition for adsorbtivedesulfurization experiment investigated.•The aim of this work is sulfur removal to acceptable levels by using a selective adsorptive desulfurization process.
A series of metal oxides (CuO, ZnO, CeO2)-modified zeolite Y nanocomposites were successfully synthesized via procedure comprising (i) ion-exchange (ii) precipitation and (iii) calcination method. Structural analysis of the products confirmed the nanoscale formation of nanocomposites. This study focused on hydrodesulfurization (HDS) of crude oil fraction (isodiesel) in a single reactor loaded with nanocomposites of metal oxide with high specific area and high reactivity under various operating factors such as temperature (350–390 °C), pressure (1–4 MPa), catalyst dosage (0.7–1.3 g) and weight hour space velocity (1–2 h−1) to achieve high quality of diesel. Nanocomposites could efficiently reduce sulfur compound concentration from 2000 ppm to less than 10 ppm according Euro-5 standard. High levels of sulfur compounds (98%) were removed using ZnO-zeolite Y nanocomposite under determined conditions (1 g catalyst, H2/oil mole ratio = 500, LHSV = 1 h−1, temperature = 370 °C). We could recycle ZnO-zeolite Y, 5 times without a significant decrease in catalyst activity that is useful for industrial application. Furthermore, Power Low model confirms that the HDS reaction is irreversible in fixed-bed reactor.
The figure illustrates the removal of pertechnetate from contaminated groundwater using surfactant-modified zeolite.
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•Modification of zeolite with hexadecyltrimethylammonium enhance ...anion-binding.•Modified zeolite demonstrated fast kinetics and significant sorption capacity for TcO4−.•Pertechnetate is incorporated into modified zeolite as an inner-sphere complex.•Sorbents provide a low-cost approach to binding pertechnetate under oxidized conditions.
Separation of pertechnetate (99TcO4−) from contaminated groundwater and nuclear waste streams remains a technical challenge for the long-term management of 99TcO4− released to the environment. Herein, a siliceous zeolite Y phases(s) were modified with cationic surfactant and subsequently used to sequester TcO4− from acidic aqueous solution containing competing ions. Pristine and modified zeolite Y phase(s) were characterized with X-ray diffraction, X-ray absorption spectroscopy (XAS), sorption isotherms, zeta potential, and BET surface area measurements. Measured TcO4− sorption capacity of the modified zeolite Y (MSAV) was 337 mg/g, which was in good agreement with modeled estimates, 357 mg/g. The Langmuir and the pseudo-second-order models adequately described the sorption of TcO4−on the modified zeolite Y phases. Kinetic data suggest that liquid film diffusion and intraparticle diffusion were the rate-limiting steps governing TcO4− sorption. Analyses of the XAS spectra data revealed that ReO4−, a chemical analogue for TcO4−, was associated with the modified zeolite Y phase(s) as an inner-sphere complex of ReO4− possibly incorporated into a structural cavity, and there was no evidence of the reduced form of Re(IV). The modified zeolite Y exhibited fast sorption kinetics, significant sorption capacity, and robust uptake performance in acidic conditions (pH 3–5) and in the presence of high concentrations of competing anions. An important attribute of this remediation technology is that it sequesters TcO4− (Tc oxidized form) that exists naturally in most surface environments and waste streams, and it provides an effective alternative to the existing reductive precipitation technologies that have limited long-term environmental applications.
•Adsorption of Ag+, Cu2+, and Co2+ ions on faujasite-type zeolite Y was analyzed.•Physicochemical interpretation of adsorption mechanism was obtained via a physical model.•Characterization of the ...adsorption interactions was performed with DFT and statistical physics.
This work evaluated the potential of a synthesized faujasite-type zeolite Y as an adsorbent for the removal of relevant heavy metals such as silver (Ag+), copper (Cu2+), and cobalt (Co2+). The adsorption data of Ag+, Cu2+, and Co2+ ions were determined experimentally at pH 6 and temperatures of 298, 308, and 318 K. Two theoretical approaches have been applied based on statistical physics modeling and density functional theory (DFT) to understand and characterize the ion exchanges involved in the removal of all metals. Results showed that this zeolite was more efficient for the adsorption of Ag+ via cation-exchange. Based on the physical modelling, the removal of heavy metals on this zeolite was mono and multi-ionic (simple and multi-interactions), where the ions interacted via one and two adsorption sites. It was also noted that the temperature increment generated more available functional groups of the zeolite, facilitating the access to the smaller cavities and the interactions with the adsorbent. Adsorption energies for removing these metals with tested zeolite were slightly endothermic and were consistent with the typical values reported for ion exchange systems of heavy metals + zeolites. DFT results demonstrated that these cationic exchange energies depend on the nature of precursor salt, but with the same ranking. Both statistical and DFT approaches agreed that exchange Ag+ in zeolite Y was easier than Cu2+ and Co2+. Overall, the application of both theoretical approaches provided a reliable interpretation of the adsorption mechanism.
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•CH4/N2 adsorbents were prepared by simple zeolite Y ion-exchange with amine cations.•CH4 uptakes of decorated zeolite Y increased greatly whereas the N2 uptakes decreased.•CH4/N2 ...separation performances of decorated zeolite Y were greatly improved.•Resulting decorated zeolite Y also exhibited good regenerability and stability.
Adsorption based process for CH4/N2 separation is promising and attractive while it remains a challenge endeavor due to the lack of efficient adsorbents. In this work, amine ion-exchanged Y zeolites were developed for CH4/N2 separation. By simple ion-exchanged with tetramethylammonium cation (TMA+) and choline cation (Ch+), CH4 adsorption amounts of the resulting adsorbents were obviously increased while their N2 adsorption amounts were significantly decreased. Consequently, CH4/N2 separation performances of resulted samples were greatly improved compared to pristine NaY. CH4/N2 selectivities of resulting sample TMAY and ChY were up to 6.32 and 6.50, respectively, at 25 °C and 100 kPa. Monte Carlo calculations were used to study the interaction affinity for CH4 and N2 on the adsorbents. Breakthrough experiments were further confirmed the excellent separation performances of TMAY and ChY. The excellent separation performances of the resulting adsorbents verified the efficiency of the simple ion-exchange strategy and the application potential of the adsorbents.
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