A high-surface-area silicoaluminophosphate material rich in Brönsted acid sites as a matrix in catalytic cracking

A series of mesoporous materials Sn-SBA-16 was prepared by one-step hydrothermal synthesis with F127, TEOS and SnCl4•5H2O as template, silica source and tin source, respectively, without mineral acid added. The samples were characterized by XRD, N2 sorption, TEM and UV–Vis. The acidity property of acidic sites in the surface of the samples was investigated by pyridine-absorbed FT-IR. The results indicate that the materials exhibit high surface area and uniform pore distribution. The samples contain both Lewis and Brönsted acid sites, moreover, the total concentration of both Lewis and Brönsted acid sites increases with the decrease of the ratio of Si to Sn. And Lewis acid site plays the dominate role.

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Dynamic and Steady State Evolution of Active Sites in H-ZSM5

Catalysts ◽

10.3390/catal10040425 ◽

2020 ◽

Vol 10 (4) ◽

pp. 425

Author(s):

Khalid A. Al-Majnouni ◽

Wojciech Supronowicz ◽

Talal Aldugman ◽

Nabil Al-Yassir ◽

Ahmed Al-Zenaidi ◽

...

Keyword(s):

Steady State ◽

Catalytic Cracking ◽

Active Sites ◽

Product Distribution ◽

Acid Sites ◽

Bronsted Acid ◽

Brønsted Acid ◽

Brønsted Acid Sites ◽

Brönsted Acid ◽

Brönsted Acid Sites

Catalytic cracking of hexane over steamed ZSM-5 is studied under steady state and dynamic conditions to elucidate the role of the active sites on the product distribution. The product distribution from the riser simulator representing the dynamic state of the catalyst cannot be resembled from monocracking or bimolecular reactions by Bronsted acid sites alone. The catalyst promotes the hydride transfer function which controls the hexane conversion at 460–500 °C that flips into methanation function at 550 °C with a propene to ethene ratio of 1.04. In addition, hydrogen induction is observed in the first two pulses. Steady state data obtained from a fixed bed reactor, on the other side, shows that the product distribution is controlled by monomolecular cracking with low yield of methane and high propene to ethene ratio ranging from 4.3 to 3.3 depending on the temperature and conversion. We are not able to explain these data by considering the Bronsted acid sites alone and suggest that Lewis acid sites with short-lived activity are not inactive in the carbon-carbon activation before fading by coke deactivation. The reported findings are of importance to academia and industry and are very relevant to fluid catalytic cracking (FCC) processes.

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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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