N2 Physisorption Research Articles

Synthesis of Ag-modified ZnO/MWCNT nanoparticles and their application as a catalyst in the degradation of methylene blue

Ag-ZnO/MWCNT composites were obtained by microwave-assisted, varying-charge synthesis of multiwalled carbon nanotubes (MWCNT). The structural, morphological and optical properties were characterized by: XRD, SEM, TEM, Physisorption of N2 and UVVis. The incorporation of Ag ions and MWNTC caused changes in the structure tension and in the average crystallite size of ZnO. The micrographs revealed that ZnO agglomerates were distributed on the MWNTC and that Ag particles were deposited on the surface of the heterostructure, thus the energy gap decreased. The percentages of degradation of methylene blue were 98 and 75% under ultraviolet and visible radiation, respectively, in the Ag-ZnO/CNT composites.

Glycerol Conversion into Allyl Alcohol Using a Coke‐tolerant ZnAl2O4‐β Zeolite Catalyst: Effect of Structural, Textural, and Acidic Properties on Catalytic Stability

AbstractCatalysts with different ZnAl2O4 contents impregnated in beta zeolite were synthesized and their catalytic activity in glycerol dehydration to allyl alcohol was investigated. The materials were characterized by XRD, XRF, FTIR, DRIFTS‐ pyridine, NH3‐TPD, and N2 physisorption. In addition, the surface electrostatic potential maps were generated by a molecular mechanics approach. The XRD patterns indicated a high dispersion of the ZnAl2O4, evidenced by the absence of reflections in the diffractograms, except for the sample containing the highest spinel content. The FTIR spectra indicated the presence of zinc aluminate spinel in the zeolite matrix. The DRIFTS‐pyridine and NH3‐TPD analyses indicated that the incorporation of ZnAl2O4 modifies the acidic properties of the zeolite concerning the number, type, and distribution of acid sites. The N2 physisorption tests showed the maintenance of the micro and mesoporous properties of H‐BEA after modification, despite the reduction of the specific area and pore volume values. The samples impregnated with the ZnAl2O4 phase showed larger mesopores sizes, which may favor its catalytic performance. The catalytic tests indicated the allyl alcohol production for the impregnated materials, which the best results were obtained by the sample containing 2 % of ZnAl2O4, with 90.65 % glycerol conversion and 37 % allyl alcohol selectivity due to appropriate tuning of the acidic and textural properties, as well as the presence of basic sites evidenced by CO2‐TPD analysis and electrostatic potential maps. The presence of acid‐base sites is essential to conduct hydrogen transfer, according to the proposed mechanism, generating allyl alcohol. Finally, the results with a longer reaction period showed greater stability for the sample impregnated with low spinel content, whose coke deposition was smaller, which may be related to the larger size of secondary mesopores.

Physisorption of SO2 by carbonaceous model adsorbents with tunable hierarchical pore configurations: Experiment and simulation

Adsorption removal of SO2 using activated carbons has attracted enormous attention due to its relatively low water consumption and environmental friendliness. The physisorption of SO2 is regarded as the prerequisite step of SO2 chemisorption (i.e., SO2 reacting with oxygen and moisture in the flue gas). In this study, a series of carbonaceous model adsorbents (i.e., activated carbons, ACs) with various pore hierarchy degrees and similar surface chemistry were synthesized by simply regulating the conditions of catalytic activation. The physical and chemical characteristics of the ACs were elucidated by N2 physisorption, XPS, TEM and SEM. Both dynamic breakthrough performances and isotherms of SO2 adsorption on ACs were investigated, presenting a negative correlation between pore hierarchy and SO2 saturated adsorption capacity. Compared with the fitting of semi-empirical isotherm models, classical molecular dynamic (MD) simulation can better demonstrate the spatial distribution and the local density of SO2 molecules in nanopores of ACs with diameters <2 nm.

Catalytic Steam-Reforming of Glycerol over LDHs-Derived Ni-Al Nanosheet Array Catalysts for Stable Hydrogen Production

In the present work, LDHs–derived Ni–Al nanosheet arrays (NiAl/NA) were successfully synthesized via a one–step hydrothermal method, and applied in the steam-reforming of glycerol reaction for enhanced and stable hydrogen production. The physicochemical properties of catalysts were characterized using various techniques, including XRD, SEM–EDS, XPS, N2–physisorption, Raman, and TG–DTG. The results indicate that smooth and cross–linked Ni–Al mixed metal oxide nanosheets were orderly and perpendicularly grown on the Ni foam substrate. The SEM line scan characterization reveals the metal concentration gradient from the bottom to the top of nanosheet, which leads to distinctly optimized Ni valence states and an optimized binding strength to oxygen species. Owing to the improved reducibility and more exposed active sites afforded by its array structures, the NiAl/NA catalyst shows enhanced glycerol conversion (83.1%) and a higher H2 yield (85.4%), as well as longer stability (1000 min), compared to the traditional Ni–Al nanosheet powder. According to the characterization results of spent catalysts and to density functional theory (DFT) calculations, coke deposition is effectively suppressed via array construction, with only 1.25 wt.% of amorphous carbons formed on NiAl/NA catalyst via CO disproportionation.

Fabrication of the coke-resistant and easily reducible Ni/SiC catalyst for CO2 methanation

The catalytic methanation of carbon dioxide, which is a promising process for CO2 to fuels, has been extensively investigated using Ni-based catalysts due to their high CH4 selectivity, high CO2 conversion, and affordability. However, owing to its highly exothermic nature, CO2 methanation can cause severe carbon deposition and sintering effects, resulting in catalyst deactivation. This is where high thermal conductivity SiC presents itself as a viable alternative support to enhance the performance of Ni-based catalysts. In this work, Ni catalysts supported on a cheap commercial SiC were prepared by wet impregnation method with different Ni loadings and calcination temperatures. The as-prepared and spent catalysts were characterized using N2 physisorption, X-ray diffraction, H2 temperature-programmed reduction (H2-TPR), temperature-programmed oxidation (TPO) and transmission electron microscopy. H2-TPR analysis revealed that reduction at 400 °C for 15 min is enough to convert most of NiO to active Ni0 to archive the highest activity toward CO2 methanation. The catalytic performance and long-term stability of the as-prepared Ni/SiC catalysts were evaluated for CO2 methanation at stoichiometric CO2/H2 ratio of 1/4, different gas hourly space velocities, reaction temperatures, and reduction conditions. Among the synthesized catalysts, the 10%Ni/SiC-500 exhibited highest CO2 conversion (70%) and CH4 selectivity (98%) as well as stable catalytic performance for 30 h on stream at a GHSV of 20,000 h−1 and reaction temperature of 400 °C.

Novel Sol-Gel Synthesis of TiO2 Spherical Porous Nanoparticles Assemblies with Photocatalytic Activity.

For this study, the synthesis of TiO2 nanomaterials was performed via a novel sol-gel method employing titanium butoxide as a metal precursor, Pluronic F127 as a templating agent, toluene as a swelling agent, and acidic water or ethanol as the reaction solvents. The method was designed by tailoring certain reaction parameters, such as the sequence of toluene addition, magnetic stirring, the type of reaction solvent, and the calcination conditions. Analysis of the specific surface area and porosity was carried out via N2 physisorption, whereas the morphological features of the solids were investigated via transmission electron microscopy. The crystalline structure of both the dried powders and the calcined materials was evaluated using X-ray diffraction analysis. It transpired that the different phase compositions of the solids are related to the specific synthesis medium employed. Under the adopted reaction conditions, ethanol, which was used as a reaction solvent, promoted the local arrangement of dispersed anatase particles, the specific arrangement of which does not lead to rutile transformation. Conversely, the use of water alone supported high-particle packing, evolving into a rutile phase. The photodegradation of Rhodamine B was used as a target reaction for testing the photocatalytic activity of the selected samples.

Solar photocatalytic degradation of polyethylene terephthalate nanoplastics: Evaluation of the applicability of the TiO2/MIL-100(Fe) composite material

For the first time, TiO2/MIL-100(Fe) photocatalysts supported on perlite mineral particles prepared by the solvothermal/microwave methods and post-annealing technique were tested in the degradation of polyethylene terephthalate nanoplastics (PET NPs). Powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy, N2 physisorption, photoluminescence emission spectroscopy, photocurrent response, and electrochemical impedance spectroscopy were used to characterize the as-prepared materials. The response surface methodology approach was used to study the effects: pH of the NPs suspension and incorporated amount of MIL-100(Fe) on the TiO2/MIL-100(Fe) catalyst to optimize the photocatalytic degradation of the PET NPs under simulated solar light. The degradation of the PET NPs was evaluated by measuring turbidity and carbonyl index (FTIR) changes. The total organic carbon (TOC) in the solution during the degradation of the PET NPs was assessed to measure NPs oxidation into water-soluble degradation by-products. The active species involved in the photocatalytic degradation of PET NPs by the TiO2/MIL-100(Fe) composite was further examined based on trapping experiments. The use of 12.5 wt% TiO2/MIL-100(Fe) catalyst showed improved photocatalytic efficacy in the oxidation of PET NPs at pH 3 under simulated sunlight compared to bare TiO2. The increase in the carbonyl index (CI = 0.99), the reduction in the turbidity ratio (0.454), and the increase in the content of TOC released (3.00 mg/L) were possible with 12.5 wt% TiO2/MIL-100(Fe) material. In contrast, the PET NPs were slowly degraded by TiO2-based photocatalysis (CI = 0.96, turbidity ratio = 0.539, released TOC = 2.12 mg/L). The mesoporous TiO2/MIL-100(Fe) composites with high specific surface area, capacity to absorb visible light, and effective separation of photogenerated electron-hole charges clearly demonstrated the enhancement of the photocatalytic performance in the PET NPs degradation under simulated solar light.

Bifunctional Pt Catalysts Supported on a Zeolite-Binder Matrix for the Hydrodeoxygenation of Isoeugenol for Renewable Jet Fuel Production

Hydrodeoxygenation (HDO) of isoeugenol was carried out at 200 °C and 30 bar of H2 in a batch reactor using a series of bifunctional catalysts consisting of platinum supported on zeolite H-Beta-25 or H-Beta-300 and Bindzil as a binder. The purpose of the matrix was to understand the effect of the binder on the reaction, emulating the components of industrial catalysts and therefore facilitating catalyst scale-up. The effect of the supports acid strength, the location of metal nanoparticles, and their proximity to acid sites was also studied. The catalysts were characterized by N2 physisorption, inductively coupled plasma atomic emission spectrometry, Fourier transform infrared spectroscopy of adsorbed pyridine and scanning and transmission electron microscopy. It was found that platinum supported only on the zeolite was more active compared to platinum located on the binder. High levels of isoeugenol conversion (ca. 100%), propylcyclohexane yield (56%) and the liquid-phase mass balance (68%) were obtained for the catalyst consisting of Pt supported on both zeolite H-Beta-25 and Bindzil.

Stable Sulfonic MCM-41 Catalyst for Furfural Production from Renewable Resources in a Biphasic System

An MCM-41-SO3H catalyst with 14 wt% S was successfully synthesized to be used in furfural production from xylose and hemicellulose in a biphasic n-butanol/water system. The precursor MCM-41 and the acid-functionalized MCM-41-SO3H catalyst were characterized by XRD, FTIR, TEM, N2 physisorption, ICP-MS, TPD-NH3, and XPS. The characterization results indicated that the sulfonic process partially decreased the ordered mesoporous structure and increased the acid strength of the initial MCM-41. The catalytic performance of the xylose conversion was evaluated in a batch-type reactor using different biphasic ecological and renewable n-butanol/water ratios (1:1, 1.5:1, 2:1, and 2.5:1) as dissolvent at 170 °C. The effect of the dissolvent mixture was clearly seen from the larger initial reaction rate and TOF values for the 1.5:1 ratio. This catalytic behavior indicated that a proper proportion of n-butanol/water dissolvent mixture enhanced the solubility of the substrate in the n-butanol-rich mixture and prevented the deactivation of acidic sulfonated surface groups. To achieve transformation of lignocellulosic raw material to value-added products, the MCM-41-SO3H catalyst was also used for the production of furfural. The recycling evaluation tests indicated that for the recovered catalyst submitted to a sulfonation process, the yield of furfural was closer to the fresh catalyst.

Effect of CNT over structural properties of SAPO-34 in MTO process: Experimental and molecular simulation studies

The hierarchical silicoaluminophosphate (SAPO-34) catalyst was synthesized using the mixtures of diethylamine (D) and butylamine (B) as a structure-directing agent (SDA), and carbon nanotube (CNT) as a secondary template in the hydrothermal method. The catalysts were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), N2 physisorption, and temperature-programmed desorption of ammonia (NH3-TPD) techniques and evaluated for the catalytic activity in the Methanol to Olefins (MTO) process. The results showed that the use of CNT as the secondary template improved the hierarchical structure of SAPO-34 due to increasing the external surface area and mesoporosity and decreasing the particle size and as a result, made better the performance of the prepared SAPO-34 zeolite in the MTO process. Among all the prepared samples, the CNT-B-D catalyst synthesized by mixing three templates displayed the highest ethylene and propylene selectivity of 49% and 34%, respectively. Also, using CNT in the synthesis of samples increased the catalytic stability. In addition, pure, binary, and ternary adsorption isotherms and diffusivities of the main products and reactants over the SAPO-34 were investigated by theoretical measurements, because sorption and diffusion affect the catalyst stability and C2–C3 selectivity in the MTO reaction. The higher diffusion rate of ethylene leads to following the aromatic-based cycle in the MTO process.

Application of ozone to enhance the defluoridation property of activated alumina: A novel approach

Drinking water containing high fluoride concentrations may lead to serious health problems. Thus, aiming at water defluoridation through adsorption, several adsorbent materials have been studied worldwide. Due to its low cost and selectivity for fluoride ions, activated alumina (AA) is one of the most applied materials. At the same time, AA has low adsorption capacity, the pH of the aqueous solution must be less than 6.0 for fluoride adsorption, and it requires a long contact time to reach adsorption equilibrium. This study investigated the use of ozone to enhance the defluoridation property of AA. For this purpose, AA was treated under various ozonation conditions. Subsequently, the ozone-treated AA (OAA) samples were applied to adsorb fluoride from an aqueous solution. The influence of some ozonation parameters (AA concentration, pH, and contact time) was evaluated by carrying out adsorption experiments under fixed conditions. As a result, by full-factorial central composite rotational design (CCRD) and response surface methodology (RSM), it was found that the effect of initial pH during the ozonation is negligible on improving the defluoridation property of AA. At the same time, the decrease of AA concentration in the ozonation system significantly enhances the defluoridation property of AA. For example, the ozonation of 10 g L−1 of AA at a pH of 7.0 increased the fluoride removal efficiency of this material from 77.4% to 98.3%. Finally, the analysis of the ozonation time (0–120 min) showed that 90 min are sufficient to promote a significant rise in the fluoride removal efficiency of AA (from 78.3% to 97.4%). AA was characterized by FTIR, SEM, EDX NMR, and N2 physisorption methods to elucidate factors responsible for the increased fluoride removal efficiency when the material is ozonized.

Synthesis of calcium carbonate-loaded mesoporous SBA-15 nanocomposites for removal of phosphate from solution.

Removal of phosphate from water is very crucial for protecting the ecological environment since massive phosphorus fertilizers have been widely used and caused serious water deterioration. Thus, we fabricated a series of calcium carbonate-loaded mesoporous SBA-15 nanocomposites with different Ca:Si molar ratio (CaAS-x) as phosphorus adsorbents via a simple wet-impregnation method. The multiply approaches including X-ray diffraction (XRD), N2 physisorption, thermogravimetric mass spectrometry (TG-MS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) were used to characterize the structure, morphology, and composition of mesoporous CaAS-x nanocomposites. The phosphate adsorption efficiency of the CaAS-x nanocomposites was studied through adsorption and desorption batch tests. Results showed that the increases of Ca:Si molar ratio (rCa:Si) improved the phosphate removal capacity of CaAS nanocomposites, especially CaAS with the optimum synthesis molar ratio of Ca:Si as 0.55 showed the high adsorption capacity of 92.0 mg·g-1 to high concentration of phosphate (> 200 mg·L-1). Note that the CaAS-0.55 had a fast exponentially increased adsorption capacity with increasing the phosphate concentration and correspondingly showed a much faster phosphate removal rate than pristine CaCO3. Apparently, mesoporous structure of SBA-15 contributed to high disperse of CaCO3 nanoparticles leading to the monolayer chemical adsorption complexation formation of phosphate calcium (i.e., =SPO4Ca, =CaHPO4-, and =CaPO4Ca0). Therefore, mesoporous CaAS-0.55 nanocomposite is an environmental-friendly adsorbent for effective removal of high concentration of phosphate in neutral contaminated wastewater.

Transformation of vegetable oils into green diesel over Ni-Mo catalysts supported on titania

Reduced NiMo catalysts supported on titania for transformation of vegetable oils to green diesel have been studied. A series of six catalysts with total metal content equal to 50% and various [Ni/(Ni+Mo)] atomic ratios was prepared following deposition-precipitation method, using urea as precipitating agent. The catalysts were characterized by N2 physisorption, XRD, XPS, H2-TPR, and NH3-TPD. They were evaluated for the transformation of various crude oils, namely sunflower oil, rapeseed oil, soybean oil and cardoon oil, to green diesel, in a high-pressure (40 bar) semi-batch reactor, at 310 °C and under solvent free conditions. A synergistic [Ni/(Ni+Mo)] atomic ratio equal to 0.99 was determined. The catalyst with this formulation exhibited high metallic nickel active surface in combination with high oxygen vacancies population provided by reduced Mo-species. Over this catalyst, the crude vegetable oils were transformed to green diesel achieving yields of 65 ± 2%.

Synthesis of acidic modified UiO‐66 by concentrated sulphation form and its application in the production of fatty acids ethyl esters

AbstractIn this article, UiO‐66 metal–organic frameworks containing structural modifications were synthesized and characterized to increase acidic surface behaviour for application in heterogeneous acid catalysis to produce fatty acid ethyl esters (FAEE) from degummed soybean oil. The solvothermal route synthesized UiO‐66, and the post‐synthesis acid modifications were done by sulphation reaction in strong acidic medium. The synthesized materials were characterized by physicochemical techniques such as X‐ray diffraction (XRD), C‐ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectrometer (FTIR), and N2 physisorption, observing a strong structural modification of the original UiO‐66, but no signal of sulphated ZrO2 was presented. However, the acidic characteristics on the material's surface were increased. A central compound centred on face 23 experiments design was carried out to evaluate three essential reaction variables: temperature, time, and alcohol/oil ratio, obtaining an optimized fit for the UiO‐66‐S35 of temperature at 140°C, time of 3 h, and molar ratio of 16. The optimized statistical adjustment was applied in the reuse cycles assays in three catalyst cycles, reaching the maximum yield of 95% in FAEE, keeping the catalyst active at the end of 3 cycles.

Plasma-catalytic synthesis of ammonia over Ru/BaTiO3-based bimetallic catalysts: Synergistic effect from dual-metal active sites

Plasma-catalytic synthesis of ammonia (NH3) was carried out using BaTiO3 supported Ru-M bimetallic catalysts (Ru-M/BaTiO3, M = Fe, Co and Ni) in a dielectric barrier discharge (DBD) reactor. The NH3 synthesis performance followed the order of Ru-Ni/BaTiO3 > Ru/BaTiO3 > Ru-Co/BaTiO3 > Ru-Fe/BaTiO3, with the highest NH3 concentration (3895 ppm) and energy yield (0.39 g kWh−1) achieved over Ru-Ni/BaTiO3 at 25 W and 10 W, respectively. To gain insights into the physio-chemical properties of the Ru-M/BaTiO3 catalysts, comprehensive catalyst characterizations were performed, including X-ray diffraction, N2 physisorption measurements, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), and temperature-programmed desorption of CO2 and N2 (CO2 and N2-TPD). The results indicated that the loading of Ni enhanced the basicity and N2 adsorption capacity of the catalyst, as well as the density of oxygen vacancy (OV) on the BaTiO3 surface, which facilitated the adsorption and activation of N2 on catalyst surface. These effects led to the enhanced NH3 synthesis, as excited N2 could be adsorbed on Ru-Ni/BaTiO3 from plasma region and stepwise hydrogenated to form NHx species and ultimately NH3.

Coupling thermal and catalytic cracking of polymer wastes to boost carbon nanotubes production: Effects of HZSM-5 zeolites

The efficient synthesis of carbon nanotubes from polymer wastes has been considered one promising technology for the effective management of current environment crisis. In the two-stage reaction system, HZSM-5 zeolites were introduced into the two-stage reaction system between the upper and lower stages, which was expected to upgrade the pyrolysis gas from polymer wastes and boost the growth of carbon nanotubes on Fe-Al2O3 catalyst. The physicochemical properties of HZSM-5 zeolites, Fe-Al2O3 catalyst and the as-obtained carbon materials were systematically characterized by XRD, N2 physisorption, 27Al MAS NMR, NH3-TPD, H2-TPR, SEM, TEM, TG-DSC and Raman. It was found that the presence of HZSM-5 zeolites increased the length and yield, and narrowed the diameter of carbon nanotubes. In the absence of HZSM-5 zeolites, the yield of carbon nanotubes was 34 mg/g with an average diameter of 19 nm. The introduction of HZSM-5 and meso-HZSM-5 increased the yield of carbon nanotubes to 109 mg/g and 90 mg/g, and recduced the average diameter to 15 nm and 13 nm, respectively. The improvement of HZSM-5 zeolites on the synthesis of carbon nanotubes was observed for divrese polymer wastes inlcluding LDPE, HDPE and PP. It was attributed to the unique acidity and porosity of HZSM-5 zeolites, which enhanced the secondary cracking of the pyrolysis gas and the formation of light hydrocarbons.

Drug Delivery on Mg-MOF-74: The Effect of Drug Solubility on Pharmacokinetics.

Biocompatible metal-organic frameworks (MOFs) have emerged as potential nanocarriers for drug delivery applications owing to their tunable physiochemical properties. Specifically, Mg-MOF-74 with soluble metal centers has been shown to promote rapid pharmacokinetics for some drugs. In this work, we studied how the solubility of drug impacts the pharmacokinetic release rate and delivery efficiency by impregnating various amounts of ibuprofen, 5-fluorouracil, and curcumin onto Mg-MOF-74. The characterization of the drug-loaded samples via X-ray diffraction (XRD), N2 physisorption, and Fourier transform infrared (FTIR) confirmed the successful encapsulation of 30, 50, and 80 wt % of the three drugs within the MOF structure. Assessment of the drug delivery performances of the MOF under its various loadings via HPLC tests revealed that the release rate is a direct function of drug solubility and molecular size. Of the three drugs considered under fixed loading condition, the 5-fluorouracil-loaded MOF samples exhibited the highest release rate constants which was attributed to the highest degree of solubility and smallest molecular size of 5-fluorouracil relative to ibuprofen and curcumin. It was also noted that the release kinetics decreases with drug loading, due to a pharmacokinetic shift in release mechanism from singular to binary modes of compound diffusion. The findings of this study highlight the effects of drug's physical and chemical properties on the pharmacokinetic rates from MOF nanocarriers.

Hydro-co-processing of a jatropha oil and gas oil blend with a sulfided Ni–W catalyst supported on mesostructured materials Al(x)-SBA-15 type for cleaner hybrid diesel production: Effect of the Al/Si molar ratio

Obtaining cleaner hybrid diesel fractions by hydro-co-processing vegetable oil and gas oil blends requires tailoring intrinsic properties (metal content and acidity) of a solid catalyst. Such catalyst must promote the hydrodesulfurization (HDS), hydrodeoxygenation (HDO), and hydrocracking (HCK) reactions. In that sense, the present research work reports the synthesis (sol–gel and hydrothermal), characterization (N2 physisorption, XRD, HR-TEM, 27Al-MAS-NMR, Pyridine-FTIR, and RAMAN spectroscopy), and catalytic evaluation (6 MPa of H2 initial pressure, 360 °C, and 4 h) for Ni–W/Al(x)-SBA-15 sulfided catalysts during the hydroprocessing of a 20 vol% of Jatropha Curcas L. oil blend with a mixed gas oil (50 vol% LGO and 50 vol% HGO). Metal content of the catalysts was fixed at 2.5 wt% of NiO and 15 wt% of WO3, meanwhile, the Al/Si (x) molar ratio was adjusted in 0.1, 0.05, 0.033, 0.025, and 0.0 to study the effect of aluminum (Al) content during hydroprocessing. Liquid products were analyzed by FTIR, 1H NMR, ESI-MS, Simulated Distillation (ASTM D2887) and ASTM D4294 for S content. The effect of Al incorporation was mainly observed in the hydrotreating reactions (HDO and HDS) rather than HCK reactions. Intermediate Al/Si molar ratios (0.05, and 0.03) promoted the highest sulfur removal of about 13.1 % compared with the 10.7 % and 5.6 % for 0.1 and 0.025 Al/Si molar ratios, respectively. In addition, the highest content of Brønsted (0.05 mmol g−1) and Lewis (1.45 mmol g−1) acid sites was observed for the Ni–W/Al(0.05)-SBA-15 catalyst. Regarding HDO activity, it was the highest (57.3 %) for Ni–W/Al(0.1)-SBA-15 catalyst, and the lowest (30.9 %) for Ni–W/Al(0.025)-SBA-15, and Ni–W/Al(0.0)-SBA.15 sulfided catalysts. Finally, by comparing HDS and HCK activities of Ni–W/Al(0.05)-SBA-15 and Ni–W/Al(0.0)-SBA-15 sulfided catalysts, it was observed that HDS decreased 7.5 % and HCK increased 2.4 % when no Al was incorporated.

Reactive adsorption desulfurization of model FCC gasoline on Ni-based adsorbents: Effect of active phase dispersion on activity and HDS/HYD selectivity

A series of Ni/ZnO-Al2O3 and Ni/ZnO-SiO2 adsorptive-catalytic adsorbents differing in the support composition (the Al2O3, SiO2 and ZnO covered) and nickel surface content have been synthesized. Zinc oxide-based supports and Ni supported adsorbents were characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and N2 physisorption to study their structural properties and morphology. Desulfurization (HDS) and hydrogenation (HYD) activity of the synthesized systems, as well as the HDS/HYD selectivity factor (SF) were determined in the process of reactive adsorption of model FCC gasoline containing thiophene (1000 ppm of sulfur) and 1-hexene (20 wt%) on a fixed-bed flow-type laboratory unit. It has been established that an increase in the nickel surface content and average particle size of the active phase leads to an enhancement of the HDS/HYD selectivity factor regardless of the support used. The Ni/ZnO-SiO2 sample with 8 at Ni/nm2 exhibited the highest HDS/HYD selectivity at a high level of thiophene conversion (> 96%) in the chemisorption mode. The evolution of catalytic properties of Ni-Zn sorbents during FCC gasoline desulfurization process was estimated as well as characteristics of sulfurized samples. Relationships between the turnover frequency number in HDS and HYD reactions, HDS/HYD selectivity factor and size of Ni particles are discussed. DFT calculations of the adsorption thermodynamics were carried out for three model components and adsorption in the diffusion-controlled mode of the feedstock was studied for a series of nickel clusters. The results helped to explain the catalytic behavior of Ni-based sorbents in chemisorption and catalytic (after sulfur saturation) conditions.

Catalytic dehydration of fructose to 5-hydroxymethylfurfural over mesoporous Nb-W oxide solid acid catalyst

In this study, a mesoporous Nb-W oxide solid acid catalyst was synthesized and characterized in detail by TEM, N2 physisorption, and Py-FTIR. Effects of the calcination temperature on the pore structure and acid properties were investigated. The results showed that increasing calcination temperature from 400 °C to 600 °C remarkably affected the characteristics of mesoporous Nb-W oxides, with a decrease in specific surface area, pore volume, and acid amount, but an increase in pore size from 5.1 nm to 10.4 nm. Furthermore, a notable decrease was found in both the fructose conversion and HMF yield in the dehydration of fructose to HMF over Nb-W oxides when increasing the calcination temperature, and the catalyst could keep high catalytic activity and selectivity after recycling 4 times. Solvents also played a key role in the fructose dehydration to HMF over the Nb-W oxides, and DMSO was the optimized solvent. 1H NMR and 13C NMR experiments revealed that the key intermediate, 4-hydroxy-5-hydroxymethyl-4,5-dihydrofuran-2-carbaldehyde, could generate in DMSO but not in other solvents including NMP, DMF, DMAC, and EG.