Influence of aluminium incorporation in the preparation of zirconia-pillared clay and catalytic performance in the acetalization reaction

AbstractThe exchange reaction of Na-bentonite with zirconium pillars gives products which suffer from a loss of crystallinity, with basal spacing about 18 Å and surface area of 200 m2 g–1. Aluminium introduced in different amounts in the zirconium intercalated solution leads to an improvement in the stability and crystallinity of zirconia-pillared clays (Zr-PILCs) and creates pillared clays with new properties. Adding a small amount of Al (10 molar %) leads to an increase of d001 from 18 Å to 20.5 Å and an increase of the percentage of introduced zirconium from 16.71 to 21, expressed as ZrO2 wt.%, accompanied by an increase of the Brönsted and Lewis acidic sites. The acetalization of acetone with ethylene glycol was studied in order to compare the activity of PILCs. The results show that the yield of the aforementioned reaction depends strongly of the composition and acidity of the catalyst.

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Effect of Fe Additives on the Catalytic Performance of Ion-Exchanged CsX Zeolites for Side-Chain Alkylation of Toluene with Methanol

Catalysts ◽

10.3390/catal9100829 ◽

2019 ◽

Vol 9 (10) ◽

pp. 829 ◽

Cited By ~ 4

Author(s):

Zhang ◽

Yuan ◽

Miao ◽

Li ◽

Shan ◽

...

Keyword(s):

Catalytic Activity ◽

Catalytic Performance ◽

High Yield ◽

Side Chain ◽

Impregnation Method ◽

Basic Sites ◽

Lewis Acidic Sites ◽

X Zeolite ◽

Acidic Sites ◽

Negative Effect

The side-chain alkylation of toluene with methanol was investigated over some Fe-modified Cs ion-exchanged X zeolite (CsX) catalysts prepared via the impregnation method using different iron sources. The absorption/activation behaviors of the reactants on the surface of the catalysts were studied by in situ Fourier-transform infrared (FT-IR) spectroscopy and temperature programmed desorption (TPD) mass measurements. Modification of CsX with a small amount of FeCl3 could result in a considerable decrease in catalytic activity, due mainly to the remarkable decrease in the density of acidic and basic sites of the catalysts. Interestingly, the Fe(NO3)3-modified CsX with an optimum Fe loading of 0.15 wt.% shows improved catalytic activity and high yield compared to the side-chain alkylation products. Modification of CsX with Fe(NO3)3 could also result in a decrease in basic sites of the catalyst. However, such a change does not bring an obvious negative effect on the adsorption/activation of toluene, while it could effectively inhibit the generation of the undesired bidentate formate. Furthermore, the introduced FeOx species (derived from the decomposition of Fe(NO3)3) may also act as new Lewis acidic sites to participate in the activation of methanol and to stabilize the formed active intermediates (i.e., unidentate formate). Therefore, modification of CsX with a suitable amount of Fe(NO3)3 may adjust its adsorption/activation ability for reagents by changing the acid–base properties of the catalyst, which can finally enhance the catalytic performance for the side-chain alkylation of toluene with methanol.

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The Effect of Tourmaline on SCR Denitrification Activity of MnOx/TiO2 at Low Temperature

Catalysts ◽

10.3390/catal10091020 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1020

Author(s):

Yizhe Helian ◽

Suping Cui ◽

Xiaoyu Ma

Keyword(s):

Low Temperature ◽

Catalytic Reduction ◽

Catalytic Performance ◽

Scr Catalyst ◽

Highly Efficient ◽

Nh3 Scr ◽

Catalytic Material ◽

Acidic Sites ◽

Denitrification Activity ◽

The Stability

Selective catalytic reduction (SCR) technology is the most widely used flue gas denitration technology at present. The stability of a catalyst is the main factor limiting the development of this technology. In this study, an environmentally friendly and highly efficient NH3-SCR catalyst was prepared by coprecipitation method from acidolysis residue of industrial waste and tourmaline. We found that the addition of tourmaline has an important impact on the denitration activity of the catalytic material. The NOx conversion exceeded 97% at 200 °C with the dosage of 10% tourmaline, which is about 7% higher than that without doping. The improvement of catalytic performance was mostly attributed to the permanent electrodes of tourmaline, which effectively promotes the dispersion of MnOx/TiO2 catalytic materials, increases the number of acidic sites and changes the valence distribution of manganese ions in products, which speeds up the diffusion of protons and ions, resulting in the acceleration of redox reaction. These as-developed tourmaline-modified MnOx/TiO2 materials have been demonstrated to be promising as a new type of highly efficient low-temperature NH3-SCR catalyst.

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An efficient Fe2O3/HY catalyst for Friedel–Crafts acylation of m-xylene with benzoyl chloride

RSC Advances ◽

10.1039/c4ra04984e ◽

2014 ◽

Vol 4 (70) ◽

pp. 36951-36958 ◽

Cited By ~ 16

Author(s):

Manman Mu ◽

Ligong Chen ◽

Yunlong Liu ◽

Wangwang Fang ◽

Yang Li

Keyword(s):

Catalytic Activity ◽

Iron Oxide ◽

Benzoyl Chloride ◽

Catalytic Performance ◽

Reaction Parameters ◽

Hy Zeolite ◽

Lewis Acidic Sites ◽

Acidic Sites ◽

Excellent Catalytic Performance

Iron oxide supported on HY zeolite was prepared and exhibited excellent catalytic performance in the acylation of m-xylene with benzoyl chloride. It was characterized by XRD, BET, XPS, NH3-TPD and Py-IR. The catalytic activity of Fe2O3/HY is enhanced with the increase of Lewis acidic sites. Furthermore, the reaction parameters were optimized. Finally, the catalyst was easily separated reused for five runs without appreciable loss of catalytic activity.

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Magnesium Hydrogen Phosphate: An Efficient Catalyst for Acrylic Acid Production from Biorenewable Lactic Acid

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19019 ◽

2021 ◽

Vol 21 (3) ◽

pp. 1537-1548

Author(s):

Nagaraju Nekkala ◽

Putrakumar Balla ◽

Srinivasarao Ginjupalli ◽

Harisekher Mitta ◽

S. K. Hussain ◽

...

Keyword(s):

Lactic Acid ◽

Acrylic Acid ◽

Biomass Conversion ◽

Catalytic Performance ◽

Hydrogen Phosphate ◽

Efficient Catalyst ◽

Synthetic Process ◽

Calcination Temperatures ◽

Lewis Acidic Sites ◽

Acidic Sites

A series of Magnesium hydrogen phosphate (MgHP) catalysts with different magnesium to phosphorous (Mg/P) mole ratios at varying calcination temperatures has been synthesised, bearing in mind the effectiveness as well as the stability of MgHP to catalyse acrylic acid (AA) production from biorenewable lactic acid (LA), a synthetic process applicable to biomass conversion. The physicochemical properties of the MgHP catalysts have been thoroughly characterised and the formation of Mg(NH4)PO4, MgHPO4 and Mg2P2O7 with different structural and acidic properties have been reported. The high catalytic performance of MgHP catalysts with high AA yields (100% conversion and 85% selectivity) at high space velocities (WHSVLA = 3.13 h−1) have been achieved at 360 °C. NH3-Temperature programmed desorption (TPD) and pyridine FTIR have shown that the effectiveness of a catalyst is accounted for not primarily by the actual strength of acidic sites, but is due to the presence of Lewis acidic sites compared to Bronsted sites.

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Keggin-Al13 Polycations: Influence of Synthesis and Intercalation Parameters on the Structural Properties of Al-Pillared Clays

Minerals ◽

10.3390/min11111211 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1211

Author(s):

Anderson Parodia ◽

Janaina A. Prasniski ◽

Francine Bertella ◽

Sibele B. C. Pergher

Keyword(s):

Structural Properties ◽

Exchange Process ◽

Micropore Volume ◽

Pillared Clay ◽

Pillared Clays ◽

Basal Spacing ◽

Synthesis Conditions ◽

Adsorption Processes ◽

Natural Clays ◽

Pillaring Solution

Pillared clays are interesting materials with applications in catalysis and adsorption processes. To obtain these materials, several preparation procedures are necessary and must be optimized to tune the final properties of the resulting pillared clay. Therefore, this article reports the influence of synthesis parameters (temperature and concentration) of Keggin-Al13 polycations and different intercalation times (0.5 up to 72 h) on the structural properties of Al-pillared clays. The natural clays are from Brazil, and they are composed mainly of montmorillonite. By XRD, N2 sorption, XRF and 27Al NMR results of the Al-PILCs, we verified that the pillaring solution could be prepared at room temperature with an aging time of 24 h. For the cation exchange process, a period of at least 2 h is necessary to ensure the formation of pillared materials. The concentration of the Keggin-Al13 polycations was evaluated by using diluted pillaring solutions followed by applying re-pillaring procedures. After submitting the pillared clay to another pillaring process, the number of pillars in the interlamellar space increased; however, the micropore volume decreased concomitantly. Thus, by optimizing the synthesis conditions of the Keggin-Al13 polycations, Al-PILCs could be obtained with good values of basal spacing and specific surface area.

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Removal of organic matter from wastewater using M/Al-pillared clays (M = Fe or Mn) as coagulants

Water Science & Technology ◽

10.2166/wst.2018.321 ◽

2018 ◽

Vol 78 (3) ◽

pp. 534-544

Author(s):

Khadidja Gouttal ◽

Abderrezak Benghalem ◽

Goussem Mimanne ◽

Benhabib Karim

Keyword(s):

Organic Matter ◽

Water Oxidation ◽

Removal Rate ◽

Oxygen Demand ◽

Pillared Clay ◽

Pillared Clays ◽

Point Of Zero Charge ◽

Strong Interactions ◽

Basal Spacing ◽

Adsorption Sites

Abstract This work is about organic matter removal from Sidi Bel Abbes wastewater plant (Algeria) by coagulation on pillared clays (PILCs) under pH and PZC (point of zero charge), conditions. Two pillared clays, M/Al-PILCs (M = Fe or Mn), were synthesized, characterized, and studied as coagulants. Results showed that Fe/Al-pillared clay exhibits superior efficiency, with 18% higher removal rate than the common coagulants alum (AS) and ferric chloride (FCl), and that sedimentation time has positive effect on turbidity removal, with 95.85% removal rate during 30 min. Moreover PILCs will not cause pH go down too low, which is an advantage for achieving the best overall treatment. The IR and UV bands' reduction reveals the breakdown fragmentation of high molecular weight organic substances into smaller units. The highest total organic carbon (supercritical water oxidation analysis) and chemical oxygen demand adsorption capacities (48.52% and 61.85% respectively) obtained for Fe/Al-PILC can be related to increased basal spacing between adjacent layers, creating favorable adsorption sites in the microporous system. The suggested adsorption mechanism involves strong interactions between pollutants and PILCs leading to PILC–pollutant complex formation.

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

Catalysts ◽

10.3390/catal11040488 ◽

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).

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Copper Phyllosilicates-Derived Catalysts in the Production of Alcohols from Hydrogenation of Carboxylates, Carboxylic Acids, Carbonates, Formyls, and CO2: A Review

Catalysts ◽

10.3390/catal11020255 ◽

2021 ◽

Vol 11 (2) ◽

pp. 255

Author(s):

Dien-Thien To ◽

Yu-Chuan Lin

Keyword(s):

Carboxylic Acids ◽

Catalytic Performance ◽

Spatial Effect ◽

Synthesis Methods ◽

The Past ◽

Surface Areas ◽

Preparation Conditions ◽

Remedial Actions ◽

The Stability ◽

Size Interaction

Copper phyllosilicates-derived catalysts (CuPS-cats) have been intensively explored in the past two decades due to their promising activity in carbonyls hydrogenation. However, CuPS-cats have not been completely reviewed. This paper focuses on the aspects concerning CuPS-cats from synthesis methods, effects of preparation conditions, and dopant to catalytic applications of CuPS-cats. The applications of CuPS-cats include the hydrogenation of carboxylates, carboxylic acids, carbonates, formyls, and CO2 to their respective alcohols. Besides, important factors such as the Cu dispersion, Cu+ and Cu0 surface areas, particles size, interaction between Cu and supports and dopants, morphologies, and spatial effect on catalytic performance of CuPS-cats are discussed. The deactivation and remedial actions to improve the stability of CuPS-cats are summarized. It ends up with the challenges and prospective by using this type of catalyst.

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