MCM-22, MCM-36, and ITQ-2 Zeolites with Different Si/Al Molar Ratios as Effective Catalysts of Methanol and Ethanol Dehydration

MCM-22, MCM-36, and ITQ-2 zeolites with the intended Si/Al molar ratios of 15, 25, and 50 were synthetized and tested as catalysts for dehydration of methanol to dimethyl ether and dehydration of ethanol to diethyl ether and ethylene. The surface concentration of acid sites was regulated by the synthesis of zeolite precursors with different aluminum content in the zeolite framework, while the influence of porous structure on the overall efficiency of alcohol conversion was analyzed by application of zeolitic materials with different types of porosity—microporous MCM-22 as well as microporous-mesoporous MCM-36 and ITQ-2. The zeolitic samples were characterized with respect to their: chemical composition (ICP-OES), structure (XRD, FT-IR), texture (N2 sorption), and surface acidity (NH3-TPD). Comparison of the catalytic activity of the studied zeolitic catalysts with other reported catalytic systems, including zeolites with the similar Si/Al ratio as well as γ-Al2O3 (one of the commercial catalysts for methanol dehydration), shows a great potential of MCM-22, MCM-36, and ITQ-2 in the reactions of alcohols dehydration.

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Characterization and Catalytic Behaviour of Co3(PO4)2–AlPO4 Catalysts

Adsorption Science & Technology ◽

10.1177/026361749801600405 ◽

1998 ◽

Vol 16 (4) ◽

pp. 285-293 ◽

Cited By ~ 5

Author(s):

M.R. Mostafa ◽

F.Sh. Ahmed

Keyword(s):

Pore Radius ◽

Surface Acidity ◽

Total Pore Volume ◽

Textural Properties ◽

Acid Sites ◽

Adsorption Of Nitrogen ◽

Amorphous Structures ◽

Ft Ir ◽

Catalytic Behaviour ◽

The Mean

Co3(PO4)2, AlPO4 and the binary system Co3(PO4)2-AlPO4 with different compositions were prepared by the coprecipitation method. The structural properties of these samples were determined using XRD, DTA and FT-IR techniques. The textural properties were determined from the adsorption of nitrogen at 77 K. The surface acidity was measured by a calorimetric titration method. The samples were tested as catalysts in the dehydration of ethanol and isopropanol using a pulse microcatalytic technique. The data obtained from XRD and FT-IR indicate the amorphous structures of the prepared catalysts. An increase in Co3(PO4)2 content led to a decrease in the surface area and in the total pore volume and an increase in the mean pore radius. The surface acidity of the catalyst depends on the chemical composition; the surface acidity increased with an increase in the AlPO4 content. The dehydration temperature and the distribution of acid sites are important parameters in determining the selectivity and activity of the catalyst.

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Dehydration of Fructose to 5-Hydroxymethylfurfural: Effects of Acidity and Porosity of Different Catalysts in the Conversion, Selectivity, and Yield

Chemistry ◽

10.3390/chemistry3040087 ◽

2021 ◽

Vol 3 (4) ◽

pp. 1189-1202

Author(s):

João Pedro Vieira Lima ◽

Pablo Teles Aragão Campos ◽

Mateus Freitas Paiva ◽

José J. Linares ◽

Sílvia C. L. Dias ◽

...

Keyword(s):

Renewable Resources ◽

Acid Sites ◽

Pyridine Adsorption ◽

Key Factors ◽

Factors Affecting ◽

Acidic Sites ◽

General Order ◽

Ft Ir ◽

Niobic Acid ◽

N2 Sorption

There is a demand for renewable resources, such as biomass, to produce compounds considered as platform molecules. This study deals with dehydration of fructose for the formation of 5-hydroxymethylfurfural (HMF), a feedstock molecule. Different catalysts (aluminosilicates, niobic acid, 12-tungstophosphoric acid—HPW, and supported HPW/Niobia) were studied for this reaction in an aqueous medium. The catalysts were characterized by XRD, FT-IR, N2 sorption at −196 °C and pyridine adsorption. It was evident that the nature of the sites (Brønsted and Lewis), strength, quantity and accessibility to the acidic sites are critical to the conversion and yield results. A synergic effect of acidity and mesoporous area are key factors affecting the activity and selectivity of the solid acids. Niobic acid (Nb2O5·nH2O) revealed the best efficiency (highest TON, yield, selectivity and conversion). It was determined that the optimum acidity strength of catalysts should be between 80 to 100 kJ mol−1, with about 0.20 to 0.30 mmol g−1 of acid sites, density about 1 site nm−2 and mesoporous area about 100 m2 g−1. These values fit well within the general order of the observed selectivity (i.e., Nb2O5 > HZSM-5 > 20%HPW/Nb2O5 > SiO2-Al2O3 > HY > HBEA).

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Surface Characterization and Catalytic Activity of Alumina and Alumina-Supported ZnSO4 Catalysts Prepared from Different Alumina Sources

Adsorption Science & Technology ◽

10.1260/02636170260504378 ◽

2002 ◽

Vol 20 (7) ◽

pp. 695-705

Author(s):

Farid Sh. Mohamed

Keyword(s):

Catalytic Activity ◽

Surface Characterization ◽

Surface Acidity ◽

Catalyst Activity ◽

Total Pore Volume ◽

Acid Sites ◽

Aluminium Chloride ◽

Impregnation Method ◽

X Ray Diffraction ◽

Ft Ir

Three alumina samples were prepared from different sources including aluminium isopropoxide, aluminium chloride and aluminium nitrate, and were then used to prepare supported ZnSO4 catalysts via the impregnation method. The alumina and ZnSO4-supported samples were characterized by X-ray diffraction (XRD), FT-IR spectroscopy and nitrogen physisorption methods. Dehydration of 1-butanol and the cracking of cumene were undertaken over the prepared samples using a pulse microcatalytic technique. For a given alumina sample, the surface area and total pore volume decreased continuously with increasing ZnSO4 content. Loading alumina samples with ZnSO4 improved their dehydration and cracking activities. The source of alumina played a role in determining the surface acidity and catalyst activity of alumina and alumina-supported ZnSO4 catalysts. Impregnation of ZnSO4 on alumina samples resulted in an increase in the concentration of Lewis sites and the creation of Brönsted acid sites on their surfaces. The catalytic activity of the investigated catalysts was found to depend strongly on both the chemical composition and the type of acid site present on the catalyst surface.

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Analysis of the Pyrolytic Behaviour of Birch, Maple, and Rowan Leaves

Energies ◽

10.3390/en14082091 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2091

Author(s):

Valentina Zubkova ◽

Andrzej Strojwas ◽

Marcin Bielecki

Keyword(s):

Combustion Products ◽

Carbonyl Groups ◽

Chemical Parameters ◽

Chemical Reagents ◽

Urban Greenery ◽

Volatile Products ◽

Different Types ◽

Ft Ir ◽

Xrd Techniques ◽

Lower Contribution

A research study was conducted on the thermal behaviour of leaves of urban greenery (birch, maple, and rowan) and the products of their pyrolysis and extraction as assisted by microwaves. The obtained products of pyrolysis and extraction were investigated with the use of FT-IR and UV spectroscopies and XRD techniques. A contractive analysis of samples of chars, condensates, after-extraction residue, and extracts showed that the changes in structural-chemical parameters of leaves of different types of trees during pyrolysis and extraction take place in distinct ways. About 22% of material was removed from birch leaves during extraction, and more than 17% of material was extracted from maple and rowan leaves. It was determined that, during pyrolysis of after-extraction residue of leaves, many fewer PAH compounds with carbonyl groups along with alcohols and phenols are emitted than during pyrolysis of non-extracted leaves. Taking into account that pyrolysis is the first stage of combustion, a decrease in the amount of dangerous compounds in the volatile products of pyrolysis leads to a lower contribution of such compounds in combustion products. This indicates that leaves of urban greenery can be subjected to combustion after extraction, and the obtained extracts can be used as a source of phytochemicals and chemical reagents.

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Chlorine-Resistant Hollow Nanosphere-Like VOx/CeO2 Catalysts for Highly Selective and Stable Destruction of 1,2-Dichloroethane: Byproduct Inhibition and Reaction Mechanism

Processes ◽

10.3390/pr9010119 ◽

2021 ◽

Vol 9 (1) ◽

pp. 119

Author(s):

Yu Huang ◽

Shiyue Fang ◽

Mingjiao Tian ◽

Zeyu Jiang ◽

Yani Wu ◽

...

Keyword(s):

Oxygen Vacancies ◽

Acid Sites ◽

Strong Interactions ◽

Hollow Nanosphere ◽

Efficient Removal ◽

Chlorinated Volatile Organic Compounds ◽

Molar Ratios ◽

Volatile Organic ◽

Redox Ability ◽

Species Mobility

Developing economical and robust catalysts for the highly selective and stable destruction of chlorinated volatile organic compounds (CVOCs) is a great challenge. Here, hollow nanosphere-like VOx/CeO2 catalysts with different V/Ce molar ratios were fabricated and adopted for the destruction of1,2–dichloroethane (1,2–DCE). The V0.05Ce catalyst possessed superior catalytic activity, reaction selectivity, and chlorine resistance owing to a large number of oxygen vacancies, excellent low-temperature redox ability, and chemically adsorbed oxygen (O− and O2−) species mobility. Typical chlorinated byproducts (CHCl3, CCl4, C2HCl3, and C2H3Cl3) derived from the cleavage of C–Cl and C–C bonds of 1,2–DCE were detected, which could be effectively inhibited by the abundant acid sites and the strong interactions of VOx species with CeO2. The presence of water vapor benefited the activation and deep destruction of 1,2–DCE over V0.05Ce owing to the efficient removal of Cl species from the catalyst surface.

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Effect of surface acidity on the catalytic activity and deactivation of supported sulfonic acids during dehydration of methanol to DME

New Journal of Chemistry ◽

10.1039/d0nj00229a ◽

2020 ◽

Vol 44 (39) ◽

pp. 16810-16820

Author(s):

Rosanna Viscardi ◽

Vincenzo Barbarossa ◽

Daniele Mirabile Gattia ◽

Raimondo Maggi ◽

Giovanni Maestri ◽

...

Keyword(s):

Catalytic Activity ◽

Sulfonic Acid ◽

Water Resistance ◽

Surface Acidity ◽

Acid Catalyst ◽

Acid Sites ◽

Sulfonic Acids ◽

Effect Of Surface

Superiorty of the supported sulfonic acid catalyst in terms of the water resistance and efficiency of the acid sites compared to the commercial reference.

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Synthesis of Uniform Mesoporous Zeolite ZSM-5 Catalyst for Friedel-Crafts Acylation

ChemEngineering ◽

10.3390/chemengineering3020035 ◽

2019 ◽

Vol 3 (2) ◽

pp. 35 ◽

Cited By ~ 10

Author(s):

Heman Smail ◽

Mohammad Rehan ◽

Kafia Shareef ◽

Zainab Ramli ◽

Abdul-Sattar Nizami ◽

...

Keyword(s):

Surface Area ◽

Surface Acidity ◽

Analytical Techniques ◽

Acid Sites ◽

Zeolite Catalysts ◽

Gas Chromatography Mass Spectrometry ◽

Crystallographic Structure ◽

Mesoporous Zeolite ◽

Mesoporous Zeolites ◽

Surfactant Templates

This work highlights how the treatment of ZSM-5 (parent Zeolite Socony Mobil–5, Si/Al = 23) with different surfactant templates and alkaline solution, improved the catalytic performance in the Friedel-Crafts acylation of anisole with a propionic anhydride to obtain p-methoxypropiophenone. The modified microporous to mesoporous zeolite catalysts were characterized using different analytical techniques, including X-ray diffraction (XRD), nitrogen porosimetry, Fourier-transform infrared spectroscopy (FT-IR), temperature-programmed desorption (ammonia-TPD) and field emission scanning electron microscopy (FE-SEM) to analyze the crystallographic structure, surface acidity, surface area, porosity, morphology, and particle size. The results showed that the formed mesoporous zeolite by NaOH solution had smaller mesopores (ca. 3.7 nm) as compared to the mesoporous zeolites obtained by surfactant templates, such as, CTAB (ca. 14.9 nm), TPAOH (ca. 11.1 nm) and mixture of CTAB/TPAOH (ca. 15.2 nm). The catalytic acylation reaction was conducted in a batch glass reactor at various temperatures and the products were analyzed using off-line gas chromatography–mass spectrometry (GC-MS). It was found that the activity of treated ZSM-5 with mixed surfactant templates (CTAB/TPAOH) exhibited enhanced selectivity towards the main product (p-methoxypropiophenone) by a factor 1.7 or higher than unmodified ZSM-5 due to its increased surface area by 1.5 times and enhanced acid sites.

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Polymerization of n-butyl methylacrylate using bis(β- ketoamino)nickel(II)/MAO catalytic systems

e-Polymers ◽

10.1515/epoly.2008.8.1.967 ◽

2008 ◽

Vol 8 (1) ◽

Author(s):

Xiaohui He ◽

Yiwang Chen ◽

Yongming Liu ◽

Muqing Chen ◽

Shuxian Yu ◽

...

Keyword(s):

Molecular Weight ◽

Monomer Concentration ◽

Polymerization Temperature ◽

Moderate Activity ◽

Polymerization Time ◽

Catalytic Systems ◽

Molecular Weights ◽

Molar Ratios ◽

Broad Molecular Weight Distribution ◽

C Nmr

AbstractThe polymerizations of n-butyl methylacrylate (nBMA) were carried out using bis(β-ketoamino)nickel(II) complexes (Ni[CH3C(O)CHC(NR)CH3]2: R = phenyl, 1; R = naphthyl, 2) in combination with methylaluminoxane (MAO) in toluene. The effect of parameters such as polymerization temperature, Al/Ni molar ratios, polymerization time, and monomer concentration, on catalytic polymerization activity and polymer molecular weights, were examined in detail. Both of the nickel(II) catalytic systems exhibited moderate activity, and produced P(nBMA) with high molecular weight and relatively broad molecular weight distribution (Mw/Mn=2.0~3.0. The obtained polymer has been characterized by means of FTIR, 1H NMR, 13C NMR, DSC, and WAXD technique and was confirmed to be syndio-rich stereospecific P(nBMA).

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Oxidative Desulfurization of Tire Pyrolysis Oil over Molybdenum Heteropolyacid Loaded Mesoporous Catalysts

Reactions ◽

10.3390/reactions2040029 ◽

2021 ◽

Vol 2 (4) ◽

pp. 457-472

Author(s):

Jasmine Kaur ◽

Sundaramurthy Vedachalam ◽

Philip Boahene ◽

Ajay K. Dalai

Keyword(s):

Sulfur Content ◽

Photoelectron Spectroscopy ◽

Supported Catalysts ◽

Surface Acidity ◽

Oxidative Desulfurization ◽

Acid Catalyst ◽

Acid Sites ◽

Process Conditions ◽

Pyrolysis Oil ◽

X Ray

Pyrolysis oil derived from waste tires consists of sulfur content in the range of 7000 to 9000 ppm. For use in diesel engines, its sulfur content must be lowered to 10 to 15 ppm. Though conventional hydrodesulfurization is suitable for the removal of sulfur from tire pyrolysis oil, its high cost provides an avenue for alternative desulfurization technologies to be explored. In this study, oxidative desulfurization (ODS), a low-cost technology, was explored for the desulfurization of tire pyrolysis oil. Two categories of titanium-incorporated mesoporous supports with 20 wt% loaded heteropoly molybdic acid catalyst (HPMo/Ti-Al2O3 and HPMo/Ti-TUD-1) were developed and tested for ODS of tire pyrolysis oil at mild process conditions. Catalysts were characterized by X-ray diffraction, BET-N2 physisorption, and X-ray photoelectron spectroscopy (XPS). The incorporation of Ti into Al2O3 and TUD-1 frameworks was confirmed by XPS. The surface acidity of catalysts was studied by the temperature-programmed desorption of NH3 and pyridine FTIR analyses. HPMo/Ti-Al2O3 and HPMo/Ti-TUD-1 catalysts contained both Lewis and Brønsted acid sites. The presence of titanium in catalysts was found to promote the ODS activity of phosphomolybdic acid. The Ti-TUD-1-supported catalysts performed better than the Ti-Al2O3-supported catalysts for the ODS of tire pyrolysis oil. Hydrogen peroxide and cumene peroxide were found to be better oxidants than tert-butyl hydroperoxide for oxidizing sulfur compounds of tire pyrolysis oil. Process parameter optimization by the design of experiments was conducted with an optimal catalyst along with the catalyst regeneration study. An ANOVA statistical analysis demonstrated that the oxidant/sulfur and catalyst/oil ratios were more significant than the reaction temperature for the ODS of tire pyrolysis oil. It followed the pseudo-first-order kinetics over HPMo/Ti-TUD-1.

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