Incipient Wetness Impregnation Method Research Articles

Highly selective epoxidation of styrene at ambient temperature under photo-assisted condition over bimetallic Eu and Ti-doped amino-functionalized mesoporous molecular sieve

Mesoporous molecular sieves silica materials had been functionalized employing 3-aminopropyltriethoxysilane as the surface decoration agent by a post-synthesis method and Eu and Ti with different loading ratio were synchronously anchored on amino-functionalized silica framework by incipient wetness impregnation method, respectively. The structures of the synthesized samples were evaluated by means of X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectra, scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy and solid-state 29Si magic angle spinning nuclear magnetic resonance spectra. The results revealed that the highly ordered mesoporous two dimensional hexagonal structure and the mesoporous channel structure were well preserved and isolated tetrahedral surface Eu3+ and isolated [TiO4] or [HOTiO3] species were found to be grafted and highly dispersed in the amino-functionalized mesoporous framework. A significant enhancement in selectivity and conversion for the photocatalytic epoxidation of styrene has been achieved by synergistic effect based on surface ligand effect and electron density effect between Eu3+ and Ti4+ species on amino-functionalized mesoporous silica framework. The factors associated with the conversion of styrene and selectivity to styrene oxide such as the solvent, metal loading, the amount of NaOH, H2O2/Styrene, the amount of catalyst and reaction time were also investigated in details. The desired selectivity (84%) to styrene oxide and excellent conversion (32%) of styrene for the photocatalytic epoxidation of styrene with turnover frequency of 3.1 × 10−4s−1 were obtained using aqueous H2O2 as an oxidant in the presence of acetonitrile solvent under ambient temperature.

Bimetallic Ru–Pd supported on CeO2 for the catalytic partial oxidation of methane into syngas

A series of monometallic Ru, Pd, and bimetallic Ru–Pd catalysts loaded on CeO2 support have been prepared via mechanochemical and conventional incipient wetness impregnation methods and used in the partial oxidation of methane (POM) to obtain synthesis gas (H2 and CO). The influence of the preparation method, the order of addition of the metals, the Ru:Pd metal ratio, and the milling energy and time for samples prepared by the mechanochemical method, have been evaluated between 300 and 600 °C. The results revealed that bimetallic Ru–Pd/CeO2 catalysts outperform monometallic Ru–CeO2 and Pd–CeO2 for POM, both in terms of catalytic activity and stability. Additionally, the bimetallic Ru–Pd/CeO2 catalysts prepared by ball milling produced syngas at a much lower temperature compared to the conventional catalysts prepared by incipient wetness impregnation. Raman spectroscopy, temperature programmed reduction (H2–TPR), X–ray photoelectron spectroscopy (XPS) and high–resolution transmission electron microscopy (HRTEM) have been used to characterize the catalysts before and after reaction.

Influence of Cocatalysts (Ni, Co, and Cu) and Synthesis Method on the Photocatalytic Activity of Exfoliated Graphitic Carbon Nitride for Hydrogen Production.

Exfoliated graphitic carbon nitride (ex-g-CN) was synthesized and loaded with non-noble metals (Ni, Cu, and Co). The synthesized catalysts were tested for hydrogen production using a 300-W Xe lamp equipped with a 395 nm cutoff filter. A noncommercial double-walled quartz-glass reactor irradiated from the side was used with a 1 g/L catalyst in 20 mL of a 10 vol% triethanolamine aqueous solution. For preliminary screening, the metal-loaded ex-g-CN was synthesized using the incipient wetness impregnation method. The highest hydrogen production was observed on the Ni-loaded ex-g-CN, which was selected to assess the impact of the synthesis method on hydrogen production. Ni-loaded ex-g-CN was synthesized using different synthesis methods: incipient wetness impregnation, colloidal deposition, and precipitation deposition. The catalysts were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption using the Brunauer-Emmett-Teller method, and transmission electron microscopy. The Ni-loaded ex-g-CN synthesized using the colloidal method performed best with a hydrogen production rate of 43.6 µmol h-1 g-1. By contrast, the catalysts synthesized using the impregnation and precipitation methods were less active, with 28.2 and 10.1 µmol h-1 g-1, respectively. The hydrogen production performance of the suspended catalyst (440 µmol m-2 g-1) showed to be superior to that of the corresponding immobilized catalyst (236 µmol m-2 g-1).

SO2 resistance of CeO2- and Co3O4-supported activated carbon during removal of mercury from flue gas: A comparative study

How to enhance the SO2 tolerance of transition metal oxide-supported activated carbon is one of the hottest issues in the field of mercury capture from flue gas. Addition of a foreign metal ion to prepare bimetallic adsorbent is a common method of improving the SO2 tolerance of adsorbent. However, this approach suffers from high cost and a complex preparation process. In this study, CeO2- and Co3O4-supported activated carbon (m%CeO2/AC and m%Co3O4/AC), with various loading values of active center, were prepared by an incipient wetness impregnation method, and their SO2 tolerances were compared. The mercury removal performance and SO2 tolerance of both CeO2/AC and Co3O4/AC could be remarkably improved through increasing the loading amount of the active center. Co3O4/AC exhibited high affinity with SO2, and the chemisorbed oxygen in Co3O4 would be largely consumed, when SO2 was present in the flue gas, resulting in a significant decrease of mercury removal efficiency. The mercury removal efficiencies of 20%CeO2/AC, 40%CeO2/AC and 60%CeO2/AC were 86.1%, 93.7% and 93.7%, respectively, during removal of mercury from flue gas at 150 °C in the presence of SO2. 20%CeO2/AC was the optimal adsorbent for mercury capture from flue gas, owing to its excellent mercury removal efficiency, strong SO2 tolerance and relatively lower cost. The mercury species formed over spent 20%CeO2/AC were HgO and HgSO4. The HgO was generated through the reaction of mercury and chemisorbed oxygen, while the formation of HgSO4 was due to the reaction between mercury, SO2 and chemisorbed oxygen. The regeneration investigation indicated that the activity of spent 20%CeO2/AC could be almost fully recovered through a temperature-programmed decomposition and desorption process. The present study showed that the SO2 tolerance of CeO2/AC could be easily improved through regulation of the loading amount of the active center.

PtMx/SBA-15 (M = Co, Cu, Ni and Zn) bimetallic catalysts for crotonaldehyde selective hydrogenation

Herein, a series of the Pt-based bimetallic catalysts (PtMx/SBA-15) are gained by using ultrasonic incipient wetness impregnation method (M = Co, Cu, Ni or Zn). The experimental results show that the catalytic performance (including catalytic activity (turnover frequency-TOF), selectivity to crotyl alcohol) of PtCox/SBA-15 for catalyzing crotonaldehyde selective hydrogenation is the best among PtMx/SBA-15. Additionally, the ratio of Pt/Co in the PtCox/SBA-15 catalysts is changed to successfully synthesize PtCo/SBA-15, PtCo2/SBA-15, PtCo5/SBA-15. It demonstrates that the selectivity of the PtCox/SBA-15 catalysts for crotonaldehyde selective hydrogenation to crotyl alcohol is significantly improved with the increase of the Co content. The PtCo5/SBA-15 catalyst provides 83.8% conversion of crotonaldehyde, 94.3% selectivity to crotyl alcohol and TOF of 910.5 h−1 under mild reaction conditions (3.0 MPa H2, 80 °C and 2.0 h). And PtCo5/SBA-15 has much better catalytic performance (higher catalytic activity and selectivity to crotyl alcohol) than PtCu5/SBA-15, PtNi5/SBA-15 and PtZn5/SBA-15. The reasons are as follows: (1) PtCo alloy forms, which is conducive to crotonaldehyde adsorption and activation; (2) there is an appropriate synergy effect between Pt and Co, greatly improving the capacity of the catalyst activating hydrogen under mild conditions; (3) the electron transfers from Co to Pt, resulting in the increase of Pt electron density and decrease of Co electron density, then the Co sites are advantageous to CO group adsorption and activation and Pt sites for H2 adsorbing and activating; (4) with the increase of the Co proportion in PtCox/SBA-15, the synergy effect between Pt and Co in PtCo alloy strengthens and thus increases the selectivity of CO group hydrogenation.

Robust salen-typed Ce-MOFs supported Fe(III) catalyst fabricated by metalloligand strategy for catalytic epoxides with alcohols

A salen-based Ce-MOFs contained rich uncoordinated imine (−CH=N−) groups (termed as N-Ce-salen) has been synthesized by using solution-diffusion method. Furthermore, the as-synthesized N-Ce-salen MOFs served as a “metalloligand” could coordinate with Fe(III) ions forming a MOFs supported Fe(III) ions catalyst via a coordination assisted preparation strategy (named as Fe-N@Ce-salen-CAP). The coordination between the uncoordinated imine (−CH=N−) and Fe(III) ions was characterized by 13C solid-state NMR, N 1s XPS, FT-IR and UV-Vis techniques. The developed Fe-N@Ce-salen-CAP catalyst delivers excellent performance for ring-opening of epoxides with alcohols reaction in comparison with that Ce-salen MOFs (using the same organic linker) without containing uncoordinated imine groups supported Fe(III) catalyst (named as Fe/Ce-salen-IWI) prepared by classic incipient wetness impregnation (IWI) method. Various characterization techniques, e.g. XPS, TEM, HADDF-STEM, were employed to reveal the origin of enhanced performance of Fe-N@Ce-salen-CAP catalyst for ring-opening of epoxides with alcohols. We anticipate that this coordination-assisted preparation strategy may provide a new avenue for synthesis of other highly efficient MOFs supported catalysts for other heterogeneous catalytic reactions.

MESOPOROUS SILICOALUMINATE MATERIALS (MCM-41, SBA-15 AND MCF) BY ATRANE ROUTE FOR COBALT CATALYST

In this work, the synthesis of mesoporous silicoaluminum supports synthesized by the atrane route was performed. The obtained supports presented high homogeneity of the aluminum dispersion, high surface area and narrow pore size distribution. The synthesized mesoporous supports were: MCM-41, SBA-15 and MCF with 10% of Al2 O3 in the matrix of SiO2 . Twelve percent of cobalt was added to these supports by the incipient wetness impregnation method. These materials were characterized by adsorption of Nitrogen (BET-BJH), Scanning Microscopy Electron (SEM), X-Ray Diffraction (XDR), H2 Temperature-Programmed Reduction (TPR) and NH3 Temperature-Programmed Desorption (TPD). According to their structural properties of these catalysts, a promising application in the Fischer- Tropsch syntheses (FTS) is identified.

Atomically dispersed SrOx species on exposed {2 2 2} facets of pyrochlore La2Zr2O7 nanocrystals for boosting low-temperature oxidative coupling of methane

The efficient catalysts of strontium oxide (SrOx) supported on exposed {222} facets of pyrochlore La2Zr2O7 nanocrystals (SrOx/LZO-Y) were elaborately synthesized by incipient wetness impregnation method. The introduction of atomically dispersed SrOx species on La2Zr2O7 surface can increase the amount of surface oxygen vacancies induced by Sr2+ substitution of La3+ cations, and the increasing of moderate surface alkaline sites are beneficial to enhance catalytic performance for oxidative coupling of methane (OCM). The SrOx/LZO-Y catalysts have super catalytic performance during low-temperature OCM reaction. SrOx/LZO-12 catalyst with the highest concentrations of O2– species exhibits the highest activity and the lowest apparent activation energy (84 kJ mol−1) during low-temperature OCM into C2H4 and C2H6 (C2) products, i.e., its CH4 conversion, selectivity and yield of C2 products at 600 °C are 30.5 %, 47.4 % and 14.5 %, respectively, and its ratio of C2H4/C2H6 products is 0.77. Based on the results of multiple experimental characterizations, the mechanism of SrOx/LZO-Y catalysts for OCM reaction is proposed: the surface alkaline active centers (O2–) induced by doping of Sr ions can promote the critical step of CH4 activation significantly during low-temperature OCM reaction. It is a new strategy to develop the low-temperature and high-activity catalysts for OCM in practical application.

Household food waste conversion to biohydrogen via steam gasification over copper and nickel-loaded SBA-15 catalysts

Household food waste (FW) was converted into biohydrogen-rich gas via steam gasification over Ni and bimetallic Ni (Cu-Ni and Co-Ni) catalysts supported on mesoporous SBA-15. The effect of catalyst method on steam gasification efficiency of each catalyst was investigated using incipient wetness impregnation, deposition precipitation, and ethylenediaminetetraacetic acid metal complex impregnation methods. H2-TPR confirmed the synergistic interaction of the dopants (Co and Cu) and Ni. Furthermore, XRD and HR-TEM revealed that the size of the Ni particle varied depending on the method of catalyst synthesis, confirming the formation of solid solutions in Co– or Cu-doped Ni/SBA-15 catalysts due to dopant insertion into the Ni. Notably, the exceptional activity of the Cu-Ni/SBA-15-EMC catalyst in FW steam gasification was attributed to the fine distribution of the concise Ni nanoparticles (9 nm), which resulted in the highest hydrogen selectivity (62 vol%), gas yield (73.6 wt%). Likewise, Cu-Ni solid solution decreased coke to 0.08 wt%.

Evaluation of Synthesis Method of Fe Loaded Amorphous Silica on the Adsorption of Glyphosate

Amorphous silica from sugarcane bagasse ash (Si-BA) was extracted and used as a support for iron (Fe). The FeSO4 was loaded onto the Si-BA by 3 different methods consisting of refluxing (RF), incipient wetness impregnation (IWI) and physical mixing (PM) methods. The prepared materials used as glyphosate adsorbents were Fe/Si-BA-RF, Fe/Si-BA-IWI and Fe/SI-BA-PM. All adsorbents were further studied by several techniques. There were X-ray diffraction (XRD), energy dispersive X-ray fluorescence (ED-XRF), N2 adsorption-desorption, diffused reflected UV-Visible (DR-UV-Vis) techniques and pH Drift method. The Fe was highly dispersed onto the Si-BA with Fe loading of approximately 2.36-2.55%wt. The Fe/Si-BA-IWI and Fe/Si-BA-PM exhibited a large amount of FexOy oligomer and Fe2O3 species as compared to the Fe/Si-BA-RF. Then, the glyphosate adsorption kinetic was further studied over the Si-BA and all Fe loaded Si-BA. The adsorption kinetic of glyphosate could be described by pseudo-second order kinetic model for all adsorbents. Moreover, the Langmuir and Freundlich isotherm models were applied to study the adsorption isotherms. All adsorbents were fitted well with the Freundlich isotherm model. Based on the Freundlich isotherm, the relative adsorption capacity of the adsorbents could be determined from the Freundlich isotherm constant (KF). The Fe/Si-BA-IWI provided a higher KF value than Fe/Si-BA-PM, Fe/Si-BA-RF and Si-BA, respectively. As the results, the synthesis method of Fe loaded amorphous silica affected the glyphosate adsorption capacity. The highest capacity of Fe/Si-BA-IWI was attributed to its predominately observed FexOy oligomer and Fe2O3 species.

Chemical State of Potassium on the Surface of Iron Oxides: Effects of Potassium Precursor Concentration and Calcination Temperature.

Potassium is used extensively as a promoter with iron catalysts in Fisher–Tropsch synthesis, water–gas shift reactions, steam reforming, and alcohol synthesis. In this paper, the identification of potassium chemical states on the surface of iron catalysts is studied to improve our understanding of the catalytic system. Herein, potassium-doped iron oxide (α-Fe2O3) nanomaterials are synthesized under variable calcination temperatures (400–800 °C) using an incipient wetness impregnation method. The synthesis also varies the content of potassium nitrate deposited on superfine iron oxide with a diameter of 3 nm (Nanocat®) to reach atomic ratios of 100 Fe:x K (x = 0–5). The structure, composition, and properties of the synthesized materials are investigated by X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier-transform infrared, Raman spectroscopy, inductively coupled plasma-atomic emission spectroscopy, and X-ray photoelectron spectroscopy, as well as transmission electron microscopy, with energy-dispersive X-ray spectroscopy and selected area electron diffraction. The hematite phase of iron oxide retains its structure up to 700 °C without forming any new mixed phase. For compositions as high as 100 Fe:5 K, potassium nitrate remains stable up to 400 °C, but at 500 °C, it starts to decompose into nitrites and, at only 800 °C, it completely decomposes to potassium oxide (K2O) and a mixed phase, K2Fe22O34. The doping of potassium nitrate on the surface of α-Fe2O3 provides a new material with potential applications in Fisher–Tropsch catalysis, photocatalysis, and photoelectrochemical processes.

Study on CO2 adsorption capacity and kinetic mechanism of CO2 adsorbent prepared from fly ash

The use of fly ash from coal-fired power plants for CO2 adsorption can reduce CO2 emissions and CO2 capture costs while making efficient use of power plant solid waste. In this study, fly ash was used to prepare aerogel support with good microstructure, and the support was impregnated with an incipient wetness impregnation method to make CO2 adsorbent. Adsorption experiments of CO2 adsorbents were carried out in a self-designed small fixed-bed reactor to study the influence of reaction conditions on the adsorption capacity of adsorbents. The results showed that the aerogel support prepared from fly ash had good microscopic properties with specific surface area and specific pore volume were 400 m2/g and 1.9 cm3/g, respectively. The pore structure was uniform, and the proportion of mesopores reached more than 99%. Under the reaction condition of 60 °C reaction temperature, 15% water vapor concentration, 15% CO2 concentration and 500 mL/min total gas flow rate, the maximum adsorption capacity of KA-30 adsorbent was 2.02 mmol/g. Avrami fractional kinetics model was used to calculate the cumulative adsorption capacity to study the adsorption kinetics. Combined with mass transfer kinetic model and deactivation model, the experimental breakthrough curve was fitted to study the adsorption mechanism of the adsorbent.

Determination of Intrinsic Active Sites on CuO–CeO2–Al2O3 Catalysts for CO Oxidation and NO Reduction by CO: Differences and Connections

Based on a CeO2–Al2O3 support (CA-T) prepared by two-step incipient wetness impregnation (T-IWI) method, an efficient CuO catalyst supported on CA-T (Cu/CA-T) was successfully developed, which showed better catalytic performance in CO oxidation and NO reduction by CO (NO + CO reaction) together with higher thermal stability than the CuO catalyst loaded on conventional CeO2–Al2O3 support (Cu/CA). Based on the results of HAADF-STEM, Raman spectra, electron paramagnetic resonance, X-ray absorption spectroscopy, ex situ and quasi in situ X-ray photoelectron spectroscopy, in situ diffuse reflectance infrared Fourier transform spectroscopy, and dynamic oxygen storage capacity (OSC) testing, etc., the microstructure of CuO–CeO2–Al2O3 catalysts, especially the state of Cu species, was systemically investigated. The mechanisms of CO oxidation and NO + CO reactions on Cu/CA and Cu/CA-T catalysts were collaboratively revealed. It was found that the CA-T support with smaller CeO2 particles could facilitate the formation of more highly dispersed CuOx clusters with better redox property. In CO oxidation, more active Cu+ species could be formed on Cu/CA-T under reaction conditions due to the higher reducibility of CuOx clusters on CeO2, which contributed to its superior CO removal efficiency. After aging, a significant decrease in CO oxidation activity was observed on Cu/CA catalyst, which was mainly resulted from the disappearance of highly dispersed CuOx clusters. In clear contrast, for aged Cu/CA-T catalyst, the highly dispersed CuOx clusters could be well preserved, well explaining its much higher catalytic activity and thermal stability than the aged Cu/CA counterpart as probed by the CO oxidation reaction. In NO + CO reaction, besides the formation of more Cu+ sites for CO adsorption and activation, much higher OSC function was also achieved on the Cu/CA-T catalyst. This was due to the higher concentration of surface oxygen vacancies and moderate strength of CuOx–CeO2 interaction on Cu/CA-T, which could effectively promote the NO dissociation into [N] for N2 formation and the transfer of dissociated [O] to CO@Cu+ sites to complete the CO depletion.

Catalytic one-pot conversion of biomass-derived furfural to ethyl levulinate over bifunctional Nb/Ni@OMC

As one of the important chemical feedstocks and biofuels, ethyl levulinate (EL) can be produced from biomass-derived furfural by consecutive hydrogenation, etherification and ring-opening reactions. However, this process normally requires two separate steps in different reaction systems, which is complex and energy consumption. Herein, Nb–Ni bifunctional ordered mesoporous carbons (Nb/Ni@OMCs) were synthesized by a two-step process where Ni@OMC was firstly synthesized by a solvent evaporation induced self-assembly (EISA) process using F127 as a template agent, polyphenol gallic acid as carbon precursor and Ni2+ as cross-linker, following with the supporting of Nb species in the Ni@OMC by an incipient wetness impregnation method. The as-synthesized Nb/Ni@OMC samples were applied for the one-pot catalytic transformation of furfural to EL, and exhibited good activity with the highest EL yield of 83% under an optimized condition. Two possible pathways for the one-pot production of EL were proposed according to two intermediates: (1) hydrogenation of furfural to form furfuryl alcohol (FFA) that is then etherified with ethanol to form 2-(ethoxymethyl)furan (2-EMF); and (2) acetalization and etherification of furfural with ethanol to produce 2-(diethoxymethyl)furan (2-DMF). Then both 2-DMF and 2-EMF are converted to EL through acid catalyzed ring opening reaction. The dominant reaction pathway varied with the properties of the catalyst and the applied reaction conditions.

Effect of Zn on performance of Ni/SiO2 for hydrodeoxygenation of anisole

Herein, SiO2 supported metallic Ni (Ni/SiO2) and bimetallic Ni-Zn (NixZn/SiO2) (x represents the Ni/Zn atomic ratio) catalysts were prepared by the incipient wetness impregnation method and their activities were tested in vapor phase hydrodeoxygenation (HDO) of anisole under 0.1 MPa. The characterization results show that Ni-Zn alloy forms in NixZn/SiO2 after reduction at 550 °C, and a suitable Ni/Zn atomic ratio (30) leads to smaller alloy particle size and consequently more H2 adsorption amount than others. In the HDO reaction, the formation of Ni-Zn alloy facilitates the direct deoxygenation pathway and suppresses CO methanation and C−C bond hydrogenolysis, which is ascribed to the isolation effect of the Ni atoms by the oxophilic Zn ones. Ni30Zn/SiO2 gives not only higher anisole conversion but also higher selectivity to benzene than Ni/SiO2. Therefore, the introduction of a suitable amount of oxophilic Zn in Ni/SiO2 promotes the HDO of anisole to benzene. Finally, we propose that the Ni30Zn/SiO2 deactivation is related to the oxidation of Ni-Zn alloy and carbon deposition on the catalyst surface.

Bio-gasoline and bio-naphtha production from catalytic cracking of linseed oil methyl ester over iron- and zinc-modified HZSM-5 and γ-Al2O3 catalysts in a fixed double-beds reactor

This study investigates the catalytic cracking of linseed oil methyl ester in producing bio-naphtha and bio-gasoline fuels. The process was conducted over two beds of catalysts, including HZSM-5 (HZ) and γ-alumina (AL), in a continuous reactor. The support catalysts were modified by zinc and iron metals with various loadings (4 wt% and 8 wt%) through the incipient wetness impregnation method and characterized by XRD, XRF, FESEM-EDS, N2 adsorption-desorption, and NH3-TPD analyses. These analyses demonstrated that the existence of metals altered the textural properties and the acid site distribution of support catalysts. The experiments were carried out at the Cat. Ratio (mass ratio of AL catalyst to total mass of AL & HZ catalysts) = 0.75, WHSV = 3 h−1, T = 475 °C, P = 1 bara under N2 atmosphere. The aim was to discuss the synergistic effect of using two modified catalyst beds in production of bio-naphtha and bio-gasoline. With this respect, the general factorial design approach was employed for the statistical evaluation of the bio-naphtha and bio-gasoline production yields. The results revealed that bio-naphtha could be produced with the yield of 42.3 wt% over the double catalyst beds comprising 4ZnHZ and AL. By using 4FeHZ & AL in series, 39.0 wt% yield of bio-naphtha could be achieved. According to the bio-gasoline yield, Fe and Zn loading value of 4 wt% is the most suitable, i.e. 90.3 wt% yield on 4FeHZ-4FeAL, and 89.5 wt% yield on 4ZnHZ-4ZnAL can be obtained.

Toward n-Alkane Hydroisomerization Reactions: High-Performance Pt-Al2O3/SAPO-11 Single-Atom Catalysts with Nanoscale Separated Metal-Acid Centers and Ultralow Platinum Content.

Long-chain n-alkane hydroisomerization reaction plays a vital role in petrochemical and coal chemical industries, which could produce high-quality hydrocarbon fuels and lubricant base oils for modern transportation and mechanical drive. However, minimizing precious metal usage while maintaining the catalyst performance remains a great challenge. Herein, a novel bifunctional catalyst toward n-alkane hydroisomerization reactions, Pt-Al2O3/SAPO-11 (Pt-A/S11) featuring nanoscale separated metal-acid active centers has been synthesized via a simple two-step procedure. In detail, Pt species was first loaded on the nanometer-sized alumina matrices through an incipient wetness impregnation method and then mixed with SAPO-11 molecular sieve to form the composite catalyst. Importantly, 0.015Pt-A/S11 catalyst with the ever-reported lowest Pt loading amount of 0.015 wt % exhibits an extraordinarily high isomer yield of 85.8% compared to previous published results and the traditional Pt-SAPO-11/Al2O3 (Pt-S11/A) catalyst accompanying with the direct contact between metal and acid sites (65.6%). It has been confirmed that the Pt species in 0.015Pt-A/S11 samples exist in single-atom form, leading to an excellent hydroisomerization performance. The possible reaction processes have been discussed to elucidate the exemplary catalytic performance of the synthesized Pt-A/S11 catalysts with nanoscale intimacy of metal-acid sites.

Bifunctional Ni–CaO catalysts modified with CeO2 and inert Ca12Al14O33 for sorption-enhanced steam reforming of ethanol

In this work, sorption-enhanced steam reforming of ethanol (SE-SRE) process was studied using Ni–CaO-based bifunctional catalysts modified with Ca12Al14O33 (mayenite) and CeO2. The CaO and CaO/Ca12Al14O33 sorbents were synthesized by a sol-gel method and, subsequently, CeO2 and Ni were added by the incipient wetness impregnation method. These materials were characterized by BET surface area, thermogravimetric analysis (TGA), in situ X-ray diffraction (XRD), and in situ X-ray absorption near edge structuare (XANES). In addition, the catalysts were tested on 10 cycles of SE-SRE reaction and regeneration. In general, the characterization results revealed an inverse relationship between average crystallite size of CaO and CO2 sorption capacity. By the in situ XRD/XANES, the addition of the mayenite reduced by half the average crystallite size of CaO and increased the interaction between support and active phase. As a consequence, the catalyst containing mayenite (NiCaAl) showed the best CO2 capture uptake and stability, which could be justified mitigation of the CaO sintering effect by the inert material presence. Great stability was also observed in the catalytic tests, since the duration of the pre-breakthrough stage for NiCaAl and for the catalyst containing maynite and ceria (NiCaAlCe) remained constant over the reaction cycles. In terms of hydrogen production, NiCaAl catalyst showed the highest H2 molar fraction during the pre- (90%) and post-breakthrough. The CeO2 addition slightly favored the methane formation, although did not bring significant benefits in the CO2 capture and catalytic performance. Therefore, NiCaAl showed the best CO2 capture capacity and stability, which led to the best SE-SRE performance.

Promoting a well-dispersion of MoO3 nanoparticles on fibrous silica catalyst via one-pot synthesis for enhanced photoredox environmental pollutants efficiency

The coexistence of pharmaceutical compounds and heavy metals in the aquatic environment has resulted in complications in the treatment process and thus, causing uproar among the citizens. The radical-based photocatalysis technology has aroused as an excellent method to eliminate both heavy metal and pharmaceutical compounds in the water. Herein, reported the utilization of the microemulsion technique for the preparation of nanoporous fibrous silica-molybdenum oxide (FSMo) towards simultaneous photocatalytic abatement of hexavalent chromium (Cr(VI)) and tetracycline (TC). The FESEM analysis showed the spherical morphology of the FSMo catalyst with dendrimeric silica fiber. The synthesized FSMo catalyst exhibited narrowed bandgap, high crystallinity, and well Mo element dispersion for enhanced photo-redox of Cr(VI) and TC. Remarkably, simultaneous remediation of the Cr(VI) and TC over FSMo demonstrated superior photocatalytic efficiency, 69% and 75%, respectively, than in the individual system, possibly due to the effective separation of photoinduced charges. The introduction of the Mo element to the silica framework via microemulsion technique demonstrated better dispersion of Mo compared to the incipient wetness impregnation method and thus, yielded higher photocatalytic activity towards simultaneous removal of TC and Cr(VI). Besides, quenching experiments revealed the electrons and holes as the active species that play a dominant role in the simultaneous photo-redox of Cr(VI) and TC. Lastly, the FSMo catalyst demonstrated high stability after four continuous cycles of simultaneous photocatalysis reactions, implying its potential as a suitable material for practical wastewater treatments.

Semi-Hydrogenation of Acetylene to Ethylene Catalyzed by Bimetallic CuNi/ZSM-12 Catalysts

The purpose of this work is to develop a low-cost and high-performance catalyst for the selective catalytic hydrogenation of acetylene to ethylene. Non-precious metals Cu and Ni were selected as active ingredients for this study. Using ZSM-12 as a carrier, Cu-Ni bimetallic catalysts of CuNix/ZSM-12 (x = 5, 7, 9, 11) with different Ni/Cu ratios were prepared by incipient wetness impregnation method. The total Cu and Ni loading were 2 wt%. Under the optimal reaction conditions, the acetylene conversion was 100%, and the ethylene selectivity was 82.48%. The CuNi7/ZSM-12 prepared in this work exhibits good performance in the semi-hydrogenation of acetylene to ethylene with low cost and has potential for industrial application.