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A series of M/NiCo-Ferrite (M: Pt, Pd, Ru, and Rh) nanoparticles were successfully synthesized, through a facile sol–gel auto-combustion followed by impregnation-reduction approach, as a catalyst for hydrogen generation from hydrolysis of NaBH4. All synthesized samples were characterized by XRD, N2 adsorption–desorption method, ICP-OES, FE-SEM, and EDX analysis. Compared to the other samples, it was observed that the Rh/NiCo-Ferrite sample exhibited higher particle distribution and surface area. To evaluate the hydrogen generation rate, the hydrolysis was carried out at a temperature of 35 °C, with an aqueous solution containing 5 wt.% NaBH4 and 3 wt.% NaOH. The experimental findings indicate that the Rh/NiCo-Ferrite sample exhibited a superior rate of hydrogen generation, with an average value of 11,667 mL/min.gcat, compared to the other samples studied. Enhanced catalytic properties may be responsible for its high activity. In addition, the activation energy of hydrolysis of sodium borohydride over the Rh/NiCo-Ferrite sample was 54.5 kJ/mol which is lower than the activation energy of many Ferrite-based catalysts. Moreover, the re-usability test of the Rh/NiCo-Ferrite sample denoted a decline in the catalytic activity after 4 recycling experiments due to the alterations in morphology and the reduction in the quantity of active phase. [ABSTRACT FROM AUTHOR]

In this study, a bimetallic Co–Fe nanocatalyst supported on carbon quantum dots (CQDs) is introduced as an effective catalyst for promoting hydrogen generation upon hydrolysis of sodium borohydride. Hydrothermal synthesis routes were used to produce CQDs support. All samples were subjected to analysis using XRD, UV–Vis, Raman, FTIR, FESEM, EDX, and nitrogen adsorption-desorption techniques. Benefiting from the higher surface area (51 m 2 g r ), pore volume (0.200 m L g r ), and good dispersion of Co–Fe nanoparticles over the CQDs support, the CoFe/CQD spherical nanocatalysts with 5 wt.% iron content exhibited the highest catalytic activity of 20200 mL/min.g cat within only 1 min of reaction. The kinetics studies revealed a low activation energy of 48 kJ/mol over this optimum catalyst. In addition, it was found that the catalytic performance of this catalyst was decreased after 4 runs of recycling experiments. Catalyst degradation and leaching of the active phase were likely responsible for the decline in catalyst performance. [Display omitted] • Bimetallic Co–Fe nanocatalysts supported on carbon quantum dots CQDs were prepared. • The prepared catalysts were used for H 2 generation upon hydrolysis of NaBH 4. • CoFe/CQD with 5 wt% iron exhibited superior performance in the hydrolysis of NaBH 4. • CoFe/CQD with 5 wt% iron possessed a high hydrogen generation, 20200 mL/min.g cat. • The activation energy (E a) of this reaction was 49.5 kJ/mol over CoFe/CQD with 5 wt% iron. [ABSTRACT FROM AUTHOR]

In the present study, an easily-prepared binary metal supported on a magnetic nanocomposite of graphene oxide was synthesized with a particular focus on the sequence of metal introduction. Specifically, the Co/Ni/Fe 3 O 4 @GO, Ni/Co/Fe 3 O 4 @GO, and CoNi/Fe 3 O 4 @GO samples were synthesized, and subjected to a comprehensive characterization. Following the incorporation of nickel into the cobalt-based catalyst, the surface areas of the samples and the dispersion of the particles were notably enhanced. The positive effect of nickel introduction was found to be more pronounced in the CoNi/Fe 3 O 4 @GO nanocatalyst, which was synthesized via the simultaneous impregnation-reduction of cobalt and nickel nanoparticles. The prepared catalysts were found to be efficient catalysts in the sodium borohydride hydrolysis/methanolysis/ethanolysis process. Notably, the results revealed that the CoNi/Fe 3 O 4 @GO exhibited superior performance in the methanolysis reaction compared to the other catalysts. Impressively, this catalyst yielded a high hydrogen generation rate of 8200 mL/min.g cat. A thorough kinetic analysis of the catalyzed methanolysis reaction revealed a remarkably low activation energy of 21.45 kJ/mol. Furthermore, a thermodynamic study yielded an activation entropy (ΔS) of −97.75 J/K, which is indicative of a Langmuir-Hinshelwood-type mechanism for the methanolysis of sodium borohydride. [Display omitted] • Successful synthesis of CoNi/Fe 3 O 4 @GO was acheived by the impregnation-reduction method. • The simultaneous synthesis of CoNi/Fe 3 O 4 @GO displayed the best performance. • Addition of nickel nanoparticles in the Co/Fe 3 O 4 @GO structure improved the catalyst activity. • Low E a of 21.45 kJ/mol and high H 2 generation rate of 8200 mL/min.g cat were achieved. [ABSTRACT FROM AUTHOR]

In this study, a series of cobalt-based spinel ferrites catalysts, including nickel, cobalt, zinc, and copper ferrites, were synthesized using the sol–gel auto-combustion method followed by a chemical reduction process. These catalysts were employed for accelerating hydrogen generation via the sodium borohydride hydrolysis process. A continuous stirred tank reactor was used to perform catalytic reactor tests. All samples were subjected to analysis using XRD, FESEM, EDX, FTIR, and nitrogen adsorption–desorption techniques. The results revealed that the cobalt-based copper ferrite sample, Co/Cu-Ferrite, exhibited superior particle distribution, and porosity characteristics, as it achieved a high hydrogen generation rate of 2937 mL/min.gcat. In addition, the higher electrical donating property of Cu-Ferrite which leads to the increase in the electron density of the cobalt active sites can account for its superior performance towards hydrolysis of NaBH4. Using the Arrhenius equation and the zero-order reaction calculation, activation energy for the sodium borohydride hydrolysis reaction on the Co/Cu-Ferrite catalyst was determined to be 18.12 kJ/mol. This low activation energy compared to other cobalt-based spinel ferrite catalysts confirms the catalyst's superior performance as well. Additionally, the outcomes from the recycling experiments revealed a gradual decline in the catalyst's performance after each cycle during 4 repetitive cycles. The aforementioned properties render the Co/Cu-Ferrite catalyst an efficient catalyst for hydrogen generation through NaBH4 hydrolysis. [ABSTRACT FROM AUTHOR]

In this study, cobalt nanocatalysts supported on the Fe 3 O 4 @GO were synthesized for boosting hydrogen generation upon hydrolysis of sodium borohydride. Co/Fe 3 O 4 @GO catalysts were synthesized through a facile co-precipitation method followed by a chemical reduction step. The prepared samples were characterized using various techniques including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Vibrating sample magnetometer (VSM), and Nitrogen adsorption–desorption (BET). Benefiting from the high crystallinity, good dispersion of Co nanoparticles over the Fe 3 O 4 @GO, and the synergistic effect between Co nanoparticles and Fe 3 O 4 @GO support, Co/Fe 3 O 4 @GO catalysts with 30 wt% cobalt loading showed the highest catalytic activity with high hydrogen generation rate of 4000 mL/min.g cat and relatively good stability. To investigate the effect of the parameters on hydrogen generation rate and optimal reaction conditions, the Box-Behnken design under response surface methodology (RSM) was applied. ANOVA results denoted that the temperature with the highest F-value and lowest P-value had the most effect on the hydrogen generation rate. Under the optimum conditions including a temperature of 39.83 °C, 17.74 mg of catalyst, and 5.135 wt% NaBH 4 concentration, Co(30%)/Fe 3 O 4 @GO exhibited a superior H 2 generation rate of 6005 mL/min.g cat and low activation energy of 44.4 kJ/mol. Therefore, the Co/Fe 3 O 4 @GO is a promising catalyst for NaBH 4 hydrolysis due to its easy preparation and separation method, high hydrogen generation rate, and low activation energy. [Display omitted] • Fe 3 O 4 /GO was synthesized as a support to promote the Co-based catalyst activity and reusability. • The highest performance was obtained over a catalyst containing 30 wt% of Co nanoparticles. • Response surface methodology (RSM) was carried out to optimize the hydrogen-generation rate reaction conditions. • Over the Co(30%)/Fe 3 O 4 @GO, the activation energy was calculated to be as low as 44.4 kJ/mol. • The maximum hydrogen generation rate (HGR) obtained at optimun condition was 6005 mL/min.g cat. [ABSTRACT FROM AUTHOR]

Desulfurization of fuels is a critical process in oil refining due to the destructive effects of sulfur compounds on human health and the environment. Naphtha is an important middle distillate product, which is utilized as an automobile, engine, and jet-B fuel or blended with other fuel fractions. Therefore, the quality of the produced naphtha is essential in terms of sulfur content. Nowadays, hydrodesulfurization (HDS) is widely used in many refineries to remove the sulfur compounds from fuels. This method needs high temperature and pressure, higher investment costs, and in-situ hydrogen sources. The oxidative desulfurization (ODS) is recommended as a suitable alternative or complementary process to HDS due to the mild reaction conditions and lack of hydrogen requirement. In recent years, the oxidative desulfurization of many real fuels such as diesel has been investigated. However, a few numbers of studies reported the oxidative desulfurization of naphtha fraction. Therefore, it is essential to address the ODS challenges for naphtha, especially in mini-refinery applications. In this study, the naphtha cuts and their compounds, the mechanism of ODS, classification and comparative analysis of different ODS methods, different types of oxidants/catalysts, and the kinetics of ODS reaction have been examined comprehensively. In addition, the effect of various parameters, such as temperature, pH, catalyst content, and oxidation time on the desulfurization efficiency is investigated. Finally, the research gaps in this field have been discussed, and suggestions for future studies in the field of oxidative desulfurization of naphtha have been proposed. [ABSTRACT FROM AUTHOR]

In this study, we have investigated the effect of water co-feeds on products distribution and coking behavior of a new composite catalyst in the MTG process. A novel ZSM-5/Beta bi-phase composite catalysts were synthesized via a hydrothermal crystallization method. Catalysts were all characterized by considering their crystallinity (XRD analysis), morphology (FE-SEM analysis), surface area, pore volume (N 2 adsorption/desorption technique), and acidity (NH 3 -TPD analysis). The catalytic performance of the synthesized catalysts was tested by the MTG reaction in WHSV of 20 h−1, the temperature of 400 °C, atmospheric pressure, and water content of 0, 10, and 20%. Over the ZSM-5/Beta composite catalyst, the methanol diluted with 10% water resulted in a 29% yield of gasoline compared with 21% over ZSM-5 and 66% selectivity to alkylated aromatics compared with 45% over ZSM-5. Adding water to the methanol had a key role in improving catalysts lifetime so that by using the feed with 10 wt% water, a lifetime about two times longer than pure methanol was observed. The higher activity over the ZSM-5/Beta sample co-feed with 10% water, was ascribed to overcoming the diffusion limitations and retarding catalyst deactivation in the presence of water. [ABSTRACT FROM AUTHOR]

A new composite zeolite, ZSM-5/Beta, was developed by incorporating Beta zeolite into the synthesis gel of ZSM-5 zeolite. Beta and ZSM-5 zeolite have been prepared from rice husk ash without using an organic template. First, the effect of synthesis temperature and seeding agent on structural properties of Beta zeolite was investigated. Then, prepared Beta zeolite was added to the ZSM-5 structure with the hydrothermal method. The prepared samples were characterized by X-ray diffraction, field emission scanning electron microscopy, N 2 physical adsorption, and temperature-programmed ammonia desorption techniques. Results indicated that the synthesis at a temperature of 150 °C and using Na-Beta seeds showed suitable crystallinity as well as textural properties. Furthermore, the crystalline structure of ZSM-5 wasn't damaged by the addition of Beta zeolite. The incorporation of Beta zeolite into the ZSM-5 structure increased the total pore volume by 45%. The micropore volume and the mesopore volume also increased by 2% and 300%, respectively. Using composite zeolite led to tuning the catalyst acidity. The catalytic activity of this new ZSM-5/Beta composite structure was evaluated in the MTG process at 400 °C, WHSV of 20 h−1 and atmospheric pressure. The results illustrated that over this composite catalyst, the selectivity to alkylated aromatics increased by almost 13% compared to the initial ZSM-5 zeolite. Furthermore, gasoline production yield and catalyst lifetime also increased by 9% and 61% respectively compared to the initial ZSM-5 zeolite. The better performance of the composite zeolite can be ascribed to its higher mesoporous volume and lower acidity. The composite catalyst has a lower number of acid sites, especially the number of strong acid sites that are one of the main factors in coke deposition. Beta zeolite was synthesized using rice husk ash as a silica source and using a template free method. Beta zeolite was incorporated into the ZSM-5 structure which improved the quality of produced gasoline in the MTG process. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Beta zeolite was incorporated into the framework of ZSM-5 zeolite. • Rice husk ash was used for synthesis of this composite catalyst. • Synergetic effects of textural properties and acidity of the ZSM-5/Beta composite was shown. • The quality of produced gasoline was improved over the ZSM-5/Beta composite. • The highest catalytic activity was obtained over a catalyst containing 30 wt% of Beta zeolite. A new type of host–guest composite catalyst, ZSM-5/Beta, with a hierarchical pore system were synthesized by incorporating Beta zeolite into the structure of ZSM-5 zeolite. The crystalline, structural, textural and acid properties of the composite zeolites, as well as the parent ZSM-5, were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), nitrogen adsorption/desorption analyses (BET) and temperature programmed desorption of ammonia (NH 3 -TPD) techniques. The solid product was employed as a catalyst for methanol to gasoline reaction. Results showed that the binary structure of these catalysts, not only integrates the pore characteristics of ZSM-5 and Beta zeolites but also changes the acid properties and creating new active sites that lead to higher activity. The highest activity, gasoline yield and longer lifetime were obtained over a sample with 30 wt% Beta zeolite due to improved textural and acid properties. Over the optimized sample, selectivity to alkylated aromatics as an octane number boosters increased about 15%, gasoline yield increased by an average of 9% and 65% increase in catalyst lifetime compared to reference ZSM-5 was obtained. In addition, the decline in unfavorable durene selectivity compared to the pristine ZSM-5, from 0.98% to 0.85%, verifies the improvement in gasoline quality. [ABSTRACT FROM AUTHOR]