m-Cresol methylation: Role of internal and external acid sites in the product distribution

Solid Acids for the Reaction of Bioderived Alcohols into Ethers for Fuel Applications

Catalysts ◽

10.3390/catal9020172 ◽

2019 ◽

Vol 9 (2) ◽

pp. 172 ◽

Cited By ~ 1

Author(s):

Federica Zaccheria ◽

Nicola Scotti ◽

Nicoletta Ravasio

Keyword(s):

Physical Properties ◽

Lignocellulosic Biomass ◽

Lewis Acid ◽

Product Distribution ◽

Acid Sites ◽

Solid Acids ◽

Lewis Acid Sites ◽

Hydroxymethyl Furfural ◽

Brønsted And Lewis Acid

The use of solids acids in the synthesis of ethers suitable to be used as fuels or fuel additives were reviewed in a critical way. In particular, the role of Brønsted and Lewis acid sites was highlighted to focus on the pivotal role of the acidity nature on the product distribution. Particular emphasis is given to the recently proposed ethers prepared starting from furfural and 5-hydroxymethyl furfural. Thus, they are very promising products that can be derived from lignocellulosic biomass and bioalcohols and possess very interesting chemical and physical properties for their use in the diesel sector.

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Prominent role of mesopore surface area and external acid sites for the synthesis of polyoxymethylene dimethyl ethers (OME) on a hierarchical H-ZSM-5 zeolite

Catalysis Science & Technology ◽

10.1039/c8cy02194e ◽

2019 ◽

Vol 9 (2) ◽

pp. 366-376 ◽

Cited By ~ 11

Author(s):

Christophe J. Baranowski ◽

Ali M. Bahmanpour ◽

Florent Héroguel ◽

Jeremy S. Luterbacher ◽

Oliver Kröcher

Keyword(s):

Surface Area ◽

Acid Site ◽

Acid Sites ◽

Internal Diffusion ◽

Mfi Zeolite ◽

External Acid Sites ◽

Polyoxymethylene Dimethyl Ethers ◽

Zeolite P

By varying acid site accessibility, we demonstrated that polyoxymethylene dimethyl ethers suffered from severe internal diffusion inside a MFI zeolite.

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The role of external acid sites of ZSM-5 in deactivation of hybrid CuZnAl/ZSM-5 catalyst for direct dimethyl ether synthesis from syngas

Applied Catalysis A General ◽

10.1016/j.apcata.2014.08.030 ◽

2014 ◽

Vol 486 ◽

pp. 266-275 ◽

Cited By ~ 38

Author(s):

V.V. Ordomsky ◽

M. Cai ◽

V. Sushkevich ◽

S. Moldovan ◽

O. Ersen ◽

...

Keyword(s):

Dimethyl Ether ◽

Acid Sites ◽

External Acid Sites ◽

Dimethyl Ether Synthesis ◽

Ether Synthesis

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Opening up ZSM-5 Hierarchical Zeolite’s Porosity through Sequential Treatments for Improved Low-Density Polyethylene Cracking

Molecules ◽

10.3390/molecules25122878 ◽

2020 ◽

Vol 25 (12) ◽

pp. 2878 ◽

Cited By ~ 1

Author(s):

Karolina A. Tarach ◽

Kamila Pyra ◽

Kinga Góra-Marek

Keyword(s):

Catalytic Cracking ◽

Product Distribution ◽

Acid Sites ◽

Limiting Factors ◽

Low Density Polyethylene ◽

Low Density ◽

Ft Ir ◽

Sequential Treatments ◽

Opening Up

An adequately tuned acid wash of hierarchical ZSM-5 zeolites offers a levelling up in the catalytic cracking of low-density polyethylene. Identification of crucial and limiting factors governing the activity of the zeolite was extended with studies about the accessibility of acid sites, nature of the realuminated layer and role of Lewis acid sites. The sequential treatment of a ZSM-5 zeolite offered enhanced activity in low-density polyethylene (LDPE) cracking at low and high conversions, as confirmed by a decrease in the temperatures needed to reach 20% and 80% conversion (T20 and T80, respectively). A linear dependence of the T80 on the coupled IHF (indexed hierarchy factor) and AFB (accessibility factor) highlighted the importance of the textural and acidic parameters in the catalytic cracking of LDPE. Operando FT-IR-GC studies confirmed a higher fraction of short-chain hydrocarbons (C3–C5) in the product distribution of hierarchical catalysts resulting from the effective polymer cracking in easily accessible pores.

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Promotional Effects of Rare-Earth Praseodymium (Pr) Modification over MCM-41 for Methyl Mercaptan Catalytic Decomposition

Processes ◽

10.3390/pr9020400 ◽

2021 ◽

Vol 9 (2) ◽

pp. 400

Author(s):

Xiaohua Cao ◽

Jichang Lu ◽

Yutong Zhao ◽

Rui Tian ◽

Wenjun Zhang ◽

...

Keyword(s):

Dimethyl Sulfide ◽

Catalytic Decomposition ◽

Product Distribution ◽

Acid Sites ◽

Methyl Mercaptan ◽

Praseodymium Oxide ◽

X Ray ◽

Xps Characterization ◽

Temperature Programmed ◽

Mcm 41

Praseodymium (Pr)-promoted MCM-41 catalyst was investigated for the catalytic decomposition of methyl mercaptan (CH3SH). Various characterization techniques, such as X-ray diffraction (XRD), N2 adsorption–desorption, temperature-programmed desorption of ammonia (NH3-TPD) and carbon dioxide (CO2-TPD), hydrogen temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectrometer (XPS), were carried out to analyze the physicochemical properties of material. XPS characterization results showed that praseodymium was presented on the modified catalyst in the form of praseodymium oxide species, which can react with coke deposit to prolong the catalytic stability until 120 h. Meanwhile, the strong acid sites were proved to be the main active center over the 10% Pr/MCM-41 catalyst by NH3-TPD results during the catalytic elimination of methyl mercaptan. The possible reaction mechanism was proposed by analyzing the product distribution results. The final products were mainly small-molecule products, such as methane (CH4) and hydrogen sulfide (H2S). Dimethyl sulfide (CH3SCH3) was a reaction intermediate during the reaction. Therefore, this work contributes to the understanding of the reaction process of catalytic decomposition methyl mercaptan and the design of anti-carbon deposition catalysts.

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On the Role of Protonic Acid Sites in Cu Loaded FAU31 Zeolite as a Catalyst for the Catalytic Transformation of Furfural to Furan

Molecules ◽

10.3390/molecules26072015 ◽

2021 ◽

Vol 26 (7) ◽

pp. 2015

Author(s):

Łukasz Kuterasiński ◽

Małgorzata Smoliło-Utrata ◽

Joanna Kaim ◽

Wojciech Rojek ◽

Jerzy Podobiński ◽

...

Keyword(s):

Active Sites ◽

Acid Sites ◽

Bronsted Acid ◽

Brønsted Acid ◽

Brønsted Acid Sites ◽

Protonic Acid ◽

Brönsted Acid ◽

Brönsted Acid Sites ◽

Bronsted Acid Sites

The aim of the present paper is to study the speciation and the role of different active site types (copper species and Brønsted acid sites) in the direct synthesis of furan from furfural catalyzed by copper-exchanged FAU31 zeolite. Four series of samples were prepared by using different conditions of post-synthesis treatment, which exhibit none, one or two types of active sites. The catalysts were characterized by XRD, low-temperature sorption of nitrogen, SEM, H2-TPR, NMR and by means of IR spectroscopy with ammonia and CO sorption as probe molecules to assess the types of active sites. All catalyst underwent catalytic tests. The performed experiments allowed to propose the relation between the kind of active centers (Cu or Brønsted acid sites) and the type of detected products (2-metylfuran and furan) obtained in the studied reaction. It was found that the production of 2-methylfuran (in trace amounts) is determined by the presence of the redox-type centers, while the protonic acid sites are mainly responsible for the furan production and catalytic activity in the whole temperature range. All studied catalysts revealed very high susceptibility to coking due to polymerization of furfural.

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Catalytic role of assembled Ce Lewis acid sites over ceria for electrocatalytic conversion of dinitrogen to ammonia

Journal of Energy Chemistry ◽

10.1016/j.jechem.2021.01.016 ◽

2021 ◽

Vol 60 ◽

pp. 249-258

Author(s):

Jiamin Qi ◽

Shulan Zhou ◽

Ke Xie ◽

Sen Lin

Keyword(s):

Lewis Acid ◽

Acid Sites ◽

Lewis Acid Sites ◽

Catalytic Role

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Oxidation of Ethanol in Cu-Faujasites Studied by IR Spectroscopy

Molecules ◽

10.3390/molecules26092669 ◽

2021 ◽

Vol 26 (9) ◽

pp. 2669

Author(s):

Łukasz Kuterasiński ◽

Jerzy Podobiński ◽

Jerzy Datka

Keyword(s):

Ethanol Oxidation ◽

Produced Water ◽

Acid Sites ◽

No Adsorption ◽

Ir Studies ◽

Oxygen Donor ◽

Before And After ◽

Acetate Formation ◽

Back Donation

In this study, IR studies of the coadsorption of ethanol and CO on Cu+ cations evidenced the transfer of electrons from ethanol to Cu+, which caused the lowering of the frequency of the band attributed to CO bonded to the same Cu+ cation due to the more effective π back donation of d electrons of Cu to antibonding π* orbitals of CO. The reaction of ethanol with acid sites in zeolite HFAU above 370 K produced water and ethane, polymerizing to polyethylene. Ethanol adsorbed on zeolite Cu(2)HFAU containing acid sites and Cu+exch also produced ethene, but in this case, the ethene was bonded to Cu+ and did not polymerize. C=C stretching, which is IR non-active in the free ethene molecule, became IR active, and a weak IR band at 1538 cm−1 was present. The reaction of ethanol above 370 K in Cu(5)NaFAU zeolite (containing small amounts of Cu+exch and bigger amounts of Cu+ox, Cu2+exch and CuO) produced acetaldehyde, which was further oxidized to the acetate species (CH3COO-). As oxygen was not supplied, the donors of oxygen were the Cu species present in our zeolite. The CO and NO adsorption experiments performed in Cu-zeolite before and after ethanol reaction evidenced that both Cu+ox and Cu2+ (Cu2+exch and CuO) were consumed by the ethanol oxidation reaction. The studies of the considered reaction of bulk CuO and Cu2O as well as zeolites, in which the contribution of Cu+ox species was reduced by various treatments, suggest that ethanol was oxidized to acetaldehyde by Cu2+ox (the role of Cu+ox could not be elucidated), but Cu+ox was the oxygen donor in the acetate formation.

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