Iron Tetrasulfonatophthalocyanine-Catalyzed Starch Oxidation Using H2O2: Interplay between Catalyst Activity, Selectivity, and Stability

1995 ◽

Vol 60 (4) ◽

pp. 568-575

Author(s):

Karel Sporka ◽

Jiří Hanika ◽

Vladimír Jůn

Keyword(s):

Aqueous Solutions ◽

Active Component ◽

Catalyst Activity ◽

Gas Oil ◽

Gamma Alumina ◽

Molybdenum Sulfides ◽

Hydrodesulfurization Catalysts ◽

Hds Catalysts ◽

Kinetics Of ◽

Preparation And Evaluation

Preparation of skeletal Co-Mo catalysts by controlled impregnation of aluminosilicate skeletons containing deposited gamma-alumina with aqueous solutions of active component precursors has been investigated. The activity of the laboratory catalysts in gas oil hydrodesulfurization has been determined. Kinetics of impregnation of skeletal supports, the effect of their type, and the dependence of catalyst activity on the content of cobalt and molybdenum sulfides are reported. HDS skeletal catalysts prepared were compared with the extruded types. It was found that skeletal HDS catalysts show the higher activity (related to the content of alumina and Co-Mo sulfides) than the extruded ones due to the less significant effect of internal diffusion. However, if the activity is related to the same volume of catalyst bed, the activity of skeletal catalysts is only one fourth of that of the extruded types.

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Kinetics of carbon monoxide methanation on a Ni/SiO2 catalyst

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19901678 ◽

1990 ◽

Vol 55 (7) ◽

pp. 1678-1685

Author(s):

Vladimír Stuchlý ◽

Karel Klusáček

Keyword(s):

Carbon Monoxide ◽

Reaction Rate ◽

Catalyst Activity ◽

Adsorbed Hydrogen ◽

Reaction Products ◽

Co Methanation ◽

Molar Ratios ◽

Rate Determining Step ◽

Higher Temperature ◽

Kinetics Of

Kinetics of CO methanation on a commercial Ni/SiO2 catalyst was evaluated at atmospheric pressure, between 528 and 550 K and for hydrogen to carbon monoxide molar ratios ranging from 3 : 1 to 200 : 1. The effect of reaction products on the reaction rate was also examined. Below 550 K, only methane was selectively formed. Above this temperature, the formation of carbon dioxide was also observed. The experimental data could be described by two modified Langmuir-Hinshelwood kinetic models, based on hydrogenation of surface CO by molecularly or by dissociatively adsorbed hydrogen in the rate-determining step. Water reversibly lowered catalyst activity and its effect was more pronounced at higher temperature.

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Glycerol Hydrogenolysis with In Situ Hydrogen Produced via Methanol Steam Reforming: The Promoting Effect of Pd on a Cu/ZnO/Al2O3 Catalyst

Catalysts ◽

10.3390/catal11010110 ◽

2021 ◽

Vol 11 (1) ◽

pp. 110

Author(s):

Yuanqing Liu ◽

Chau T. Q. Mai ◽

Flora T. T. Ng

Keyword(s):

Steam Reforming ◽

Catalyst Activity ◽

Promoting Effect ◽

Glycerol Conversion ◽

Glycerol Hydrogenolysis ◽

Glycerol Dehydration ◽

Effect Of Pd ◽

Al2o3 Catalyst ◽

Reaction Equilibrium

The glycerol hydrogenolysis to produce 1,2-propanediol without using externally supplied hydrogen was investigated using methanol present in crude glycerol to provide in situ hydrogen via its steam reforming reaction. This paper focuses on the promoting effect of Pd on the reactivity of a Cu/Zn/Al2O3 catalyst. Adding 2 wt% Pd onto a Cu/ZnO/Al2O3 catalyst significantly improved the selectivity to 1,2-propanediol from 63.0% to 82.4% and the glycerol conversion from 70.2% to 99.4%. This enhancement on the catalytic activity by Pd is mainly due to the improved hydrogenation of acetol, which is the intermediate formed during the glycerol dehydration. The rapid hydrogenation of acetol can shift the reaction equilibrium of glycerol dehydration forward resulting in a higher glycerol conversion. The improved reducibility of the catalyst by Pd allows the catalyst to be reduced in situ during the reaction preventing any loss of catalyst activity due to any potential oxidation of the catalyst. The catalyst was slightly deactivated when it was firstly recycled resulting in a 5.4% loss of glycerol conversion due to the aggregation of Cu and the deactivation became less noticeable upon further recycling.

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Bio-DEE Synthesis and Dehydrogenation Coupling of Bio-Ethanol to Bio-Butanol over Multicomponent Mixed Metal Oxide Catalysts

Catalysts ◽

10.3390/catal11060660 ◽

2021 ◽

Vol 11 (6) ◽

pp. 660

Author(s):

Izabela S. Pieta ◽

Alicja Michalik ◽

Elka Kraleva ◽

Dusan Mrdenovic ◽

Alicja Sek ◽

...

Keyword(s):

Active Sites ◽

Internal Combustion Engines ◽

Mixed Oxides ◽

Catalyst Activity ◽

Product Distribution ◽

Coke Deposition ◽

Precipitation Method ◽

Mixed Metal Oxide ◽

Low Carbon ◽

Municipal Solid Wastes

Within the Waste2Fuel project, innovative, high-performance, and cost-effective fuel production methods from municipal solid wastes (MSWs) are sought for application as energy carriers or direct drop-in fuels/chemicals in the near-future low-carbon power generation systems and internal combustion engines. Among the studied energy vectors, C1-C2 alcohols and ethers are mainly addressed. This study presents a potential bio-derived ethanol oxidative coupling in the gas phase in multicomponent systems derived from hydrotalcite-containing precursors. The reaction of alcohol coupling to ethers has great importance due to their uses in different fields. The samples have been synthesized by the co-precipitation method via layered double hydroxide (LDH) material synthesis, with a controlled pH, where the M(II)/M(III) ≈ 0.35. The chemical composition and topology of the sample surface play essential roles in catalyst activity and product distribution. The multiple redox couples Ni2+/Ni3+, Cr2+/Cr3+, Mn2+/Mn3+, and the oxygen-vacant sites were considered as the main active sites. The introduction of Cr (Cr3+/Cr4+) and Mn (Mn3+/Mn4+) into the crystal lattice could enhance the number of oxygen vacancies and affect the acid/base properties of derived mixed oxides, which are considered as crucial parameters for process selectivity towards bio-DEE and bio-butanol, preventing long CH chain formation and coke deposition at the same time.

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Kinetic Modelling of Low Temperature Direct Coal Liquefaction: Consideration of Dynamic Catalyst Activity

South African Journal of Chemical Engineering ◽

10.1016/j.sajce.2021.04.001 ◽

2021 ◽

Author(s):

Ethan Gabriel Hammond ◽

Shaheen Amed Faizal Moonsamy ◽

David Lokhat ◽

Milan Carsky

Keyword(s):

Low Temperature ◽

Kinetic Modelling ◽

Catalyst Activity ◽

Coal Liquefaction ◽

Direct Coal Liquefaction

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Proline/arginine dipeptide repeat polymers derail protein folding in amyotrophic lateral sclerosis

Nature Communications ◽

10.1038/s41467-021-23691-y ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Maria Babu ◽

Filippo Favretto ◽

Alain Ibáñez de Opakua ◽

Marija Rankovic ◽

Stefan Becker ◽

...

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Protein Folding ◽

Neurodegenerative Diseases ◽

Catalyst Activity ◽

Coding Region ◽

Prolyl Isomerase ◽

X Ray Crystallography ◽

Hexanucleotide Repeat ◽

Lateral Sclerosis ◽

Dipeptide Repeat

AbstractAmyotrophic lateral sclerosis and frontotemporal dementia are two neurodegenerative diseases with overlapping clinical features and the pathological hallmark of cytoplasmic deposits of misfolded proteins. The most frequent cause of familial forms of these diseases is a hexanucleotide repeat expansion in the non-coding region of the C9ORF72 gene that is translated into dipeptide repeat polymers. Here we show that proline/arginine repeat polymers derail protein folding by sequestering molecular chaperones. We demonstrate that proline/arginine repeat polymers inhibit the folding catalyst activity of PPIA, an abundant molecular chaperone and prolyl isomerase in the brain that is altered in amyotrophic lateral sclerosis. NMR spectroscopy reveals that proline/arginine repeat polymers bind to the active site of PPIA. X-ray crystallography determines the atomic structure of a proline/arginine repeat polymer in complex with the prolyl isomerase and defines the molecular basis for the specificity of disease-associated proline/arginine polymer interactions. The combined data establish a toxic mechanism that is specific for proline/arginine dipeptide repeat polymers and leads to derailed protein homeostasis in C9orf72-associated neurodegenerative diseases.

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Modeling of a Real-Life Industrial Reactor for Hydrogenation of Benzene Process

Catalysts ◽

10.3390/catal11040412 ◽

2021 ◽

Vol 11 (4) ◽

pp. 412

Author(s):

Mirosław K. Szukiewicz ◽

Krzysztof Kaczmarski

Keyword(s):

Catalyst Activity ◽

Real Life ◽

Operating Conditions ◽

Reactor Operation ◽

Reactor Model ◽

High Scale ◽

Industrial Reactor ◽

Knowledge Based ◽

Operation Conditions ◽

Insight Into

A dynamic model of the hydrogenation of benzene to cyclohexane reaction in a real-life industrial reactor is elaborated. Transformations of the model leading to satisfactory results are presented and discussed. Operating conditions accepted in the simulations are identical to those observed in the chemical plant. Under those conditions, some components of the reaction mixture vanish, and the diffusion coefficients of the components vary along the reactor (they are strongly concentration-dependent). We came up with a final reactor model predicting with reasonable accuracy the reaction mixture’s outlet composition and temperature profile throughout the process. Additionally, the model enables the anticipation of catalyst activity and the remaining deactivated catalyst lifetime. Conclusions concerning reactor operation conditions resulting from the simulations are presented as well. Since the model provides deep insight into the process of simulating, it allows us to make knowledge-based decisions. It should be pointed out that improvements in the process run, related to operating conditions, or catalyst application, or both on account of the high scale of the process and its expected growth, will remarkably influence both the profits and environmental protection.

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