scholarly journals Metal Chlorides Grafted on SAPO-5 (MClx/SAPO-5) as Reusable and Superior Catalysts for Acylation of 2-Methylfuran Under Non-Microwave Instant Heating Condition

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 603
Author(s):  
Ismail Alhassan Auwal ◽  
Ka-Lun Wong ◽  
Tau Chuan Ling ◽  
Boon Seng Ooi ◽  
Eng-Poh Ng
Keyword(s):  
Thermochemical Treatment ◽  
Nitrogen Adsorption ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Homogeneous Distribution ◽  
Covalent Bonds ◽  
Metal Chlorides ◽  
Promising Alternative ◽  
Highly Active ◽  
Catalyst Reusability

Highly active metal chlorides grafted on silicoaluminophosphate number 5, MClx/SAPO-5 (M = Cu, Co, Sn, Fe and Zn) catalysts via simple grafting of respective metal chlorides (MClx) onto SAPO-5 are reported. The study shows that thermochemical treatment after grafting is essential to ensure the formation of chemical bondings between MClx and SAPO-5. In addition, the microscopy, XRD and nitrogen adsorption analyses reveal the homogeneous distribution of MClx species on the SAPO-5 surface. Furthermore, the elemental microanalysis confirms the formation of Si–O–M covalent bonds in ZnClx/SAPO-5, SnClx/SAPO-5 and FeClx/SAPO-5 whereas only dative bondings are formed in CoClx/SAPO-5 and CuClx/SAPO-5. The acidity of MClx/SAPO-5 is also affected by the type of metal chloride grafted. Thus, their catalytic behavior is evaluated in the acid-catalyzed acylation of 2-methylfuran under novel non-microwave instant heating conditions (90–110 °C, 0–20 min). ZnClx/SAPO-5, which has the largest amount of acidity (mainly Lewis acid sites), exhibits the best catalytic performance (94.5% conversion, 100% selective to 2-acetyl-5-methylfuran) among the MClx/SAPO-5 solids. Furthermore, the MClx/SAPO-5 solids, particularly SnClx/SAPO-5, FeClx/SAPO-5 and ZnClx/SAPO-5, also show more superior catalytic performance than common homogeneous acid catalysts (H2SO4, HNO3, CH3COOH, FeCl3, ZnCl2) with higher reactant conversion and catalyst reusability, thus offering a promising alternative for the replacement of hazardous homogeneous catalysts in Friedel–Crafts reactions.

scholarly journals Mesoporous bimetallic Fe/Co as highly active heterogeneous Fenton catalyst for the degradation of tetracycline hydrochlorides

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Junchao Li ◽  
Xuhua Li ◽  
Jindong Han ◽  
Fansheng Meng ◽  
Jinyuan Jiang ◽  
...  
Keyword(s):  
Bimetallic Catalyst ◽  
Removal Rate ◽  
Catalytic Efficiency ◽  
Nitrogen Adsorption ◽  
Catalytic Performance ◽  
Operating Parameters ◽  
Co Catalyst ◽  
Highly Active ◽  
Fenton Catalyst ◽  
Potential Applications

Abstract Mesoporous bimetallic Fe/Co was prepared as a Fenton-like catalyst to degrade the tetracycline hydrochlorides (TC). The nanocasting strategy with KIT-6 as a hard template was carried out to synthesize the mesoporous bimetallic catalyst. The mesoporous bimetallic Fe/Co catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherms, and Brunauer-Emmett-Teller (BET) method. The results showed that the catalyst has significant nanofeatures; the surface area, pore size, and particle size were 113.8 m2g−1, 4 nm, and 10 nm, respectively. In addition, the effects of the operating parameters, such as the iron-to-cobalt ratio, pH, H2O2, and initial TC concentrations on its catalytic performance were investigated. The best operating parameters were as follows: iron-to-cobalt ratio = 2:1 to 1:1, pH = 5–9, H2O2: 30 mmol, initial TC less than 30 mg/L. Furthermore, the mesoporous bimetallic Fe/Co showed a good performance for degrading TC, achieving a removal rate of 86% of TC after 3 h under the reaction conditions of H2O2 = 30 mmol, mesoporous bimetallic Fe/Co = 0.6 g/L, TC = 30 mg/L, pH = 7.0, and temperature = 25.5 °C. The mesoporous bimetallic Fe/Co catalyst shows good stability and reusability. This work demonstrated that mesoporous bimetallic Fe/Co has excellent catalytic efficiency, smaller amounts of leached ions, and wider pH range, which enhance its potential applications.

scholarly journals Surface Characteristics Change of Zinc Modified H-ZSM-5 Zeolites in Methanol to Hydrocarbons Transformation Process

2020 ◽  
Vol 6 (11) ◽  
pp. 23-30
Author(s):  
A. Sidorov ◽  
V. Molchanov ◽  
L. Mushinskii ◽  
R. Brovko
Keyword(s):  
Surface Properties ◽  
Catalyst Deactivation ◽  
Catalyst Activity ◽  
Nitrogen Adsorption ◽  
Surface Characteristics ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Transformation Process ◽  
Methanol To Hydrocarbons ◽  
Nitrogen Adsorption Isotherms

The t-plot method is a well-known method for determining the volumes of micro- and/or mesoporous materials and the specific surface area of a sample by comparison with a reference adsorption isotherm of a non-porous material having a similar surface chemical composition. The article describes the applicability of the t-graph method to the analysis of the surface properties of zinc modified samples of zeolite H-ZSM-5 before and after the reactions of methanol transformation into hydrocarbons occur on them. Zeolites are widely used as catalysts in the petrochemical and refining industries. These materials contain active Bronsted acid sites, distributed within the microporous structure of zeolites, which leads to selective catalysis due to the difference in the pore shape of the zeolites used. The size, shape of the zeolite catalyst determines the catalytic performance in terms of both product selectivity and catalyst deactivation. In most zeolite catalyzed hydrocarbon conversion reactions, catalyst activity is lost due to carbon deposition. In this connection, the determination of the surface properties of zeolites is an important task that contributes to the disclosure of the physicochemical essence of the process of deactivation of zeolites. The recalculation of nitrogen adsorption isotherms using the t-plot model made it possible to determine the volume of micro and mesopores. Based on the t-graph data, it can be concluded that during the transformation of methanol into hydrocarbons, carbon accumulates on the surface of the zeolite. In this case, the predominant deposition of carbon on the surface of mesopores, due to the fact that in the process of decontamination, from 61 to 73% of the volume of mesopores is lost. The number of micropores also decreases, but the share of losses is 42–54%, which is 10–15% lower compared to the loss of mesopore volume.

scholarly journals Insight into Active Centers and Anti-Coke Behavior of Niobium-Containing SBA-15 for Glycerol Dehydration

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 488
Author(s):  
Katarzyna Stawicka ◽  
Maciej Trejda ◽  
Maria Ziolek
Keyword(s):  
Coke Formation ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Silica Matrix ◽  
High Concentration ◽  
Active Centers ◽  
Acidic Sites ◽  
Glycerol Dehydration ◽  
Adsorption Desorption ◽  
Insight Into

Niobium containing SBA-15 was prepared by two methods: impregnation with different amounts of ammonium niobate(V) oxalate (Nb-15/SBA-15 and Nb-25/SBA-15 containing 15 wt.% and 25 wt.% of Nb, respectively) and mixing of mesoporous silica with Nb2O5 followed by heating at 500 °C (Nb2O5/SBA-15). The use of these two procedures allowed obtaining materials with different textural/surface properties determined by N2 adsorption/desorption isotherms, XRD, UV-Vis, pyridine, and NO adsorption combined with FTIR spectroscopy. Nb2O5/SBA-15 contained exclusively crystalline Nb2O5 on the SBA-15 surface, whereas the materials prepared by impregnation had both metal oxide and niobium incorporated into the silica matrix. The niobium species localized in silica framework generated Brønsted (BAS) and Lewis (LAS) acid sites. The inclusion of niobium into SBA-15 skeleton was crucial for the achievement of high catalytic performance. The strongest BAS were on Nb-25/SBA-15, whereas the highest concentration of BAS and LAS was on Nb-15/SBA-15 surface. Nb2O5/SBA-15 material possessed only weak LAS and BAS. The presence of the strongest BAS (Nb-25/SBA-15) resulted in the highest dehydration activity, whereas a high concentration of BAS was unfavorable. Silylation of niobium catalysts prepared by impregnation reduced the number of acidic sites and significantly increased acrolein yield and selectivity (from ca. 43% selectivity for Nb-25/SBA-15 to ca. 61% for silylated sample). This was accompanied by a considerable decrease in coke formation (from 47% selectivity for Nb-25/SBA-15 to 27% for silylated material).

scholarly journals Influence of Alumina Precursor Properties on Cu-Fe Alumina Supported Catalysts for Total Toluene Oxidation as a Model Volatile Organic Air Pollutant

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 252
Author(s):  
Tadej Žumbar ◽  
Alenka Ristić ◽  
Goran Dražić ◽  
Hristina Lazarova ◽  
Janez Volavšek ◽  
...  
Keyword(s):  
Surface Characterization ◽  
Iron Concentration ◽  
Catalytic Performance ◽  
Air Pollutant ◽  
Molar Ratio ◽  
Homogeneous Distribution ◽  
Total Oxidation ◽  
Alumina Support ◽  
Determining Factors ◽  
Volatile Organic

The structure–property relationship of catalytic supports for the deposition of redox-active transition metals is of great importance for improving the catalytic efficiency and reusability of the catalysts. In this work, the role of alumina support precursors of Cu-Fe/Al2O3 catalysts used for the total oxidation of toluene as a model volatile organic air pollutant is elucidated. Surface characterization of the catalysts revealed that the surface area, pore volume and acid site concentration of the alumina supports are important but not the determining factors for the catalytic activity of the studied catalysts for this type of reaction. The determining factors are the structural order of the support precursor, the homogeneous distribution of the catalytic sites and reducibility, which were elucidated by XRD, NMR, TEM and temperature programed reduction (TPR). Cu–Fe/Al2O3 prepared from bayerite and pseudoboehmite as highly ordered precursors showed better catalytic performance compared to Cu-Fe/Al2O3 derived from the amorphous alumina precursor and dawsonite. Homogeneous distribution of FexOy and CuOx with defined Cu/Fe molar ratio on the Al2O3 support is required for the efficient catalytic performance of the material. The study showed a beneficial effect of low iron concentration introduced into the alumina precursor during the alumina support synthesis procedure, which resulted in a homogeneous metal oxide distribution on the support.

scholarly journals Electron donation of non-oxide supports boosts O2 activation on nano-platinum catalysts

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tao Gan ◽  
Jingxiu Yang ◽  
David Morris ◽  
Xuefeng Chu ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Catalytic Oxidation ◽  
Pt Nanoparticles ◽  
Catalytic Performance ◽  
Nitrogen Vacancy ◽  
Innovative Strategy ◽  
Oxide Supports ◽  
Heterogeneous Catalytic ◽  
Highly Active ◽  
Electron Sink ◽  
Nitrogen Vacancies

AbstractActivation of O2 is a critical step in heterogeneous catalytic oxidation. Here, the concept of increased electron donors induced by nitrogen vacancy is adopted to propose an efficient strategy to develop highly active and stable catalysts for molecular O2 activation. Carbon nitride with nitrogen vacancies is prepared to serve as a support as well as electron sink to construct a synergistic catalyst with Pt nanoparticles. Extensive characterizations combined with the first-principles calculations reveal that nitrogen vacancies with excess electrons could effectively stabilize metallic Pt nanoparticles by strong p-d coupling. The Pt atoms and the dangling carbon atoms surround the vacancy can synergistically donate electrons to the antibonding orbital of the adsorbed O2. This synergistic catalyst shows great enhancement of catalytic performance and durability in toluene oxidation. The introduction of electron-rich non-oxide substrate is an innovative strategy to develop active Pt-based oxidation catalysts, which could be conceivably extended to a variety of metal-based catalysts for catalytic oxidation.

scholarly journals Ruling Factors in Cinnamaldehyde Hydrogenation: Activity and Selectivity of Pt-Mo Catalysts

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 362
Author(s):  
Marta Stucchi ◽  
Maela Manzoli ◽  
Filippo Bossola ◽  
Alberto Villa ◽  
Laura Prati
Keyword(s):  
Photoelectron Spectroscopy ◽  
Pt Nanoparticles ◽  
Carbon Support ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Hydrogenation Catalysts ◽  
Cinnamaldehyde Hydrogenation ◽  
Transmission Electron ◽  
Heat Treated ◽  
Heating Treatment

To obtain selective hydrogenation catalysts with low noble metal content, two carbon-supported Mo-Pt bimetallic catalysts have been synthesized from two different molybdenum precursors, i.e., Na2MoO4 and (NH4)6Mo7O24. The results obtained by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) combined with the presence and strength of acid sites clarified the different catalytic behavior toward cinnamaldehyde hydrogenation. After impregnating the carbon support with Mo precursors, each sample was used either as is or treated at 400 °C in N2 flow, as support for Pt nanoparticles (NPs). The heating treatment before Pt deposition had a positive effect on the catalytic performance. Indeed, TEM analyses showed very homogeneously dispersed Pt NPs only when they were deposited on the heat-treated Mo/C supports, and XPS analyses revealed an increase in both the exposure and reduction of Pt, which was probably tuned by different MoO3/MoO2 ratios. Moreover, the different acid properties of the catalysts resulted in different selectivity.

scholarly journals Influence of Sulfur-Containing Sodium Salt Poisoned V2O5–WO3/TiO2 Catalysts on SO2–SO3 Conversion and NO Removal

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 541 ◽  
Author(s):  
Haiping Xiao ◽  
Chaozong Dou ◽  
Hao Shi ◽  
Jinlin Ge ◽  
Li Cai
Keyword(s):  
Photoelectron Spectroscopy ◽  
No Reduction ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Impregnation Method ◽  
So2 Oxidation ◽  
Sodium Salts ◽  
X Ray ◽  
Temperature Programmed ◽  
Physical Features

A series of poisoned catalysts with various forms and contents of sodium salts (Na2SO4 and Na2S2O7) were prepared using the wet impregnation method. The influence of sodium salts poisoned catalysts on SO2 oxidation and NO reduction was investigated. The chemical and physical features of the catalysts were characterized via NH3-temperature programmed desorption (NH3-TPD), H2-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR). The results showed that sodium salts poisoned catalysts led to a decrease in the denitration efficiency. The 3.6% Na2SO4 poisoned catalyst was the most severely deactivated with denitration efficiency of only 50.97% at 350 °C. The introduction of SO42− and S2O72− created new Brønsted acid sites, which facilitated the adsorption of NH3 and NO reduction. The sodium salts poisoned catalysts significantly increased the conversion of SO2–SO3. 3.6%Na2S2O7 poisoned catalyst had the strongest effect on SO2 oxidation and the catalyst achieved a maximum SO2–SO3-conversion of 1.44% at 410 °C. Characterization results showed sodium salts poisoned catalysts consumed the active ingredient and lowered the V4+/V5+ ratio, which suppressed catalytic performance. However, they increased the content of chemically adsorbed oxygen and the strength of V5+=O bonds, which promoted SO2 oxidation.

scholarly journals Solid Acids from Persulphated and Perchlorated Physical Mixtures of Zirconium and Titanium Hydroxides

2002 ◽  
Vol 20 (10) ◽  
pp. 977-993
Author(s):  
Gamal M.S. El Shafei ◽  
Christine A. Philip
Keyword(s):  
Tetragonal Phase ◽  
Anatase Phase ◽  
Nitrogen Adsorption ◽  
Rutile Phase ◽  
Acid Sites ◽  
Solid Acids ◽  
Monoclinic Zirconia ◽  
Anion Adsorption ◽  
Physical Mixtures ◽  
Structural Aspects

Calcination at 650°C of a physical mixture of zirconium and titanium hydroxides led to the formation of the corresponding oxides, monoclinic zirconia and anatase. The adsorption of perchlorate or persulphate anions (as 0.05, 0.1, 0.2 or 0.4 M aqueous solutions) before calcination did not inhibit crystallization; however, perchlorate anions activated the formation of rutile in addition to the predominant anatase phase. Indeed, the adsorption of perchlorated anions prior to calcination allowed the thermodynamically less stable tetragonal phase of zirconia to be detected in addition to monoclinic zirconia at ambient temperature. In contrast, the adsorption of persulphate anions before calcination stabilized the tetragonal phase with no rutile phase being detected in this case. Infrared spectroscopy showed that adsorbed S2O82– anions were held more strongly by the solid than ClO4− anions which tended to decompose when the solid was calcined. The acidities of the solid acids produced because of S2O82– or ClO4−anion adsorption were studied via the adsorption of pyridine (pKa = 5.3) from cyclohexane solution. The amounts and strengths of the acid sites formed during persulphate treatment were higher than those resulting from perchlorate adsorption. The strength of the acid sites formed on samples calcined before loading with S2O82– or ClO4− anions showed no significant differences. Variations detected in the structural aspects arising from S2O82– or ClO4− anion adsorption were reflected in the texture as assessed by nitrogen adsorption at −196°C.

scholarly journals Honokiol and Magnolol: Insights into Their Antidermatophytic Effects

Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2522
Author(s):  
Adriana Trifan ◽  
Andra-Cristina Bostănaru ◽  
Simon Vlad Luca ◽  
Veronika Temml ◽  
Muhammad Akram ◽  
...  
Keyword(s):  
Negative Impact ◽  
Ex Vivo ◽  
Health Concern ◽  
Ergosterol Biosynthesis ◽  
Human Neutrophils ◽  
Traditional Use ◽  
Promising Alternative ◽  
Highly Active ◽  
Tnf Α ◽  
Significant Public Health

Dermatophyte infections represent a significant public health concern, with an alarming negative impact caused by unsuccessful therapeutic regimens. Natural products have been highlighted as a promising alternative, due to their long-standing traditional use and increasing scientific recognition. In this study, honokiol and magnolol, the main bioactives from Magnolia spp. bark, were investigated for their antidermatophytic activity. The antifungal screening was performed using dermatophyte standard strains and clinical isolates. The minimal inhibitory concentration (MIC) and the minimal fungicidal concentration (MFC) were determined in accordance with EUCAST-AFST guidelines, with minor modifications. The effects on ergosterol biosynthesis were assessed in Trichophyton rubrum cells by HPLC-DAD. Putative interactions with terbinafine against T. rubrum were evaluated by the checkerboard method. Their impact on cells’ viability and pro-inflammatory cytokines (IL-1β, IL-8 and TNF-α) was shown using an ex vivo human neutrophils model. Honokiol and magnolol were highly active against tested dermatophytes, with MIC and MFC values of 8 and 16 mg/L, respectively. The mechanism of action involved the inhibition of ergosterol biosynthesis, with accumulation of squalene in T. rubrum cells. Synergy was assessed for binary mixtures of magnolol with terbinafine (FICI = 0.50), while honokiol-terbinafine combinations displayed only additive effects (FICI = 0.56). In addition, magnolol displayed inhibitory effects towards IL-1β, IL-8 and TNF-α released from lipopolysaccharide (LPS)-stimulated human neutrophils, while honokiol only decreased IL-1β secretion, compared to the untreated control. Overall, honokiol and magnolol acted as fungicidal agents against dermatophytes, with impairment of ergosterol biosynthesis.

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