Influence of nanoscale structuralisation on the catalytic performance of ZIF-8: a cautionary surface catalysis study

AbstractThe oxidation of soot over RuRe bimetallic nanoparticles (NPs) supported on γ-Al2O3 has been investigated. The catalysts were synthesized by a microwave-polyol method and characterized by ICP, BET, TEM, STEM-EDS, XRD and XPS techniques. The study revealed that the proper choice of the Re loading (0.4–2.0 wt%) is crucial for the catalytic behavior of the 2% Ru–Re/Al2O3 nano-catalysts.The best catalytic properties, in terms of overall activity and stability, were observed for the 2%Ru-0.8%Re/γ-Al2O3 nano-catalyst. The stability of all bimetallic 2% Ru–Re nano-catalysts in catalytic soot oxidation in the presence of oxygen is very high in contrast to the 2% Ru/γ-Al2O3 sample. The presence of rhenium in the catalytic system hinder the formation of large RuO2 agglomerates leading to a better dispersion of active ruthenium phase and a better catalytic performance. The relationship between the catalytic activity of Ru–Re/γ-Al2O3 and the synergetic roles of Ru and Re is discussed.

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Influence of the Reduction Temperature and the Nature of the Support on the Performance of Zirconia and Alumina-Supported Pt Catalysts for n-Dodecane Hydroisomerization

Catalysts ◽

10.3390/catal11010088 ◽

2021 ◽

Vol 11 (1) ◽

pp. 88

Author(s):

Diana García-Pérez ◽

Maria Consuelo Alvarez-Galvan ◽

Jose M. Campos-Martin ◽

Jose L. G. Fierro

Keyword(s):

Catalytic Activity ◽

Surface Area ◽

Catalytic Properties ◽

Catalytic Performance ◽

Major Influence ◽

Pt Catalysts ◽

Reduction Temperature ◽

Metal Dispersion ◽

Tungsten Oxides ◽

Supported Pt Catalysts

Catalysts based on zirconia- and alumina-supported tungsten oxides (15 wt % W) with a small loading of platinum (0.3 wt % Pt) were selected to study the influence of the reduction temperature and the nature of the support on the hydroisomerization of n-dodecane. The reduction temperature has a major influence on metal dispersion, which impacts the catalytic activity. In addition, alumina and zirconia supports show different catalytic properties (mainly acid site strength and surface area), which play an important role in the conversion. The NH3-TPD profiles indicate that the acidity in alumina-based catalysts is clearly higher than that in their zirconia counterparts; this acidity can be attributed to a stronger interaction of the WOx species with alumina. The PtW/Al catalyst was found to exhibit the best catalytic performance for the hydroisomerization of n-dodecane based on its higher acidity, which was ascribed to its larger surface area relative to that of its zirconia counterparts. The selectivity for different hydrocarbons (C7–10, C11 and i-C12) was very similar for all the catalysts studied, with branched C12 hydrocarbons being the main products obtained (~80%). The temperature of 350 °C was clearly the best reduction temperature for all the catalysts studied in a trickled-bed-mode reactor.

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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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PtPd nanoframes derived from Pd@PdPt core–shell rhombic dodecahedrals with excellent catalytic performance toward methanol oxidation

Inorganic Chemistry Frontiers ◽

10.1039/d1qi00081k ◽

2021 ◽

Author(s):

Yangyang Ren ◽

Chuanliang Li ◽

Baosong Li ◽

Fan Gao ◽

Xinghua Zhang ◽

...

Keyword(s):

Methanol Oxidation ◽

Catalytic Properties ◽

Catalytic Performance ◽

Core Shell ◽

Acid Environment ◽

Excellent Catalytic Performance

PtPd nanoframes with excellent catalytic properties were obtained by etching Pd@PdPt core–shell RDs with Fe3+ in an acid environment.

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Effect of the ionizing radiation on the catalytic activity of the BASF K-3-10 catalyst in the low-temperature conversion of carbon monoxide by water vapour. Stability of the radiation catalytic effects

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19861571 ◽

1986 ◽

Vol 51 (8) ◽

pp. 1571-1578 ◽

Cited By ~ 26

Author(s):

Alois Motl

Keyword(s):

Carbon Monoxide ◽

Catalytic Activity ◽

Low Temperature ◽

Catalytic Effect ◽

Catalytic Properties ◽

Beta Radiation ◽

Fast Neutrons ◽

Time Interval ◽

The Stability ◽

Catalytic Effects

The radiation catalytic properties of the BASF K-3-10 catalyst were studied, namely the dependence of these effects on the time interval between the catalyst irradiation and the reaction itself and also on the length of the catalyst use. The catalytic effects decrease exponentially with the interval between the irradiation and the reaction if the catalyst is kept in the presence of air. The stability of effects induced by various types of radiations increases in the sequence beta radiation - gamma radiation - fast neutrons. The radiation catalytic effect stability in the reaction increases in the same sequence.

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Effect of Ions Substitution on Nanospace La-Fe-O Catalytic Properties for Simultaneous Removal of NOx and Soot

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.740.565 ◽

2013 ◽

Vol 740 ◽

pp. 565-569

Author(s):

Xiao Xiao Meng ◽

Mao Xiang Jing ◽

Feng Lin He ◽

Xiang Qian Shen

Keyword(s):

High Performance ◽

Catalytic Properties ◽

Catalytic Performance ◽

Dip Coating ◽

Exhaust Emission ◽

Simultaneous Removal ◽

Microstructural Characteristics ◽

Coating Method ◽

Citrate Gel Process ◽

Dip Coating Method

The catalysts La0.8K0.2FeO3(LKFO), La0.8K0.2Fe0.7Mn0.3O3(LKFMO) and La0.8K0.2Fe0.67Mn0.3Pt0.03O3(LKFMPO) were prepared by the citrate-gel process and the catalyst-coated honeycomb ceramic devices were prepared by the citrate-gel assisted dip-coating method. All the catalysts have a high performance on the simultaneous removal of NOxand soot at a temperature range of 200 to 400°C under the practical diesel exhaust emission. The obvious catalytic improvement is largely due to the effects of ions substitution, pore structure and microstructural characteristics of the catalysts. The catalytic performance order is LKFMPO > LKFMO > LKFO. Among them the LKFMPO catalyst shows the best catalytic properties, especially in the removal of NOx, with a maximum conversion rate of NOx(21.2%).

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Natural microbial polysaccharides as effective factors for modification of the catalytic properties of fungal cellobiose dehydrogenase

Archives of Microbiology ◽

10.1007/s00203-021-02424-1 ◽

2021 ◽

Author(s):

Justyna Sulej ◽

Magdalena Jaszek ◽

Monika Osińska-Jaroszuk ◽

Anna Matuszewska ◽

Renata Bancerz ◽

...

Keyword(s):

Catalytic Properties ◽

Cellobiose Dehydrogenase ◽

Pycnoporus Sanguineus ◽

Practical Applications ◽

Control Value ◽

Electrochemical Parameters ◽

Optimum Ph ◽

Stabilization Effect ◽

Fungal Polysaccharides ◽

The Stability

AbstractPolysaccharides are biopolymers composed of simple sugars like glucose, galactose, mannose, fructose, etc. The major natural sources for the production of polysaccharides include plants and microorganisms. In the present work, four bacterial and two fungal polysaccharides (PS or EPS) were used for the modification and preservation of Pycnoporus sanguineus cellobiose dehydrogenase (CDH) activity. It was found that the presence of polysaccharide preparations clearly enhanced the stability of cellobiose dehydrogenase compared to the control value (4 °C). The highest stabilization effect was observed for CDH modified with Rh110EPS. Changes in the optimum pH in the samples of CDH incubated with the chosen polysaccharide modifiers were evidenced as well. The most significant effect was observed for Rh24EPS and Cu139PS (pH 3.5). Cyclic voltammetry used for the analysis of electrochemical parameters of modified CDH showed the highest peak values after 30 days of incubation with polysaccharides at 4 °C. In summary, natural polysaccharides seem to be an effective biotechnological tool for the modification of CDH activity to increase the possibilities of its practical applications in many fields of industry.

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Directed Evolution of a Homodimeric Laccase from Cerrena unicolor BBP6 by Random Mutagenesis and In Vivo Assembly

International Journal of Molecular Sciences ◽

10.3390/ijms19102989 ◽

2018 ◽

Vol 19 (10) ◽

pp. 2989 ◽

Cited By ~ 3

Author(s):

Ji Zhang ◽

Fuying Ma ◽

Xiaoyu Zhang ◽

Anli Geng

Keyword(s):

Directed Evolution ◽

Laccase Activity ◽

Catalytic Properties ◽

Random Mutagenesis ◽

Catalytic Performance ◽

Industrial Applications ◽

Subunit Interaction ◽

Cerrena Unicolor ◽

Protein Model

Laccases have great potential for industrial applications due to their green catalytic properties and broad substrate specificities, and various studies have attempted to improve the catalytic performance of these enzymes. Here, to the best of our knowledge, we firstly report the directed evolution of a homodimeric laccase from Cerrena unicolor BBP6 fused with α-factor prepro-leader that was engineered through random mutagenesis followed by in vivo assembly in Saccharomyces cerevisiae. Three evolved fusion variants selected from ~3500 clones presented 31- to 37-fold increases in total laccase activity, with better thermostability and broader pH profiles. The evolved α-factor prepro-leader enhanced laccase expression levels by up to 2.4-fold. Protein model analysis of these variants reveals that the beneficial mutations have influences on protein pKa shift, subunit interaction, substrate entrance, and C-terminal function.

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Catalytic Performance of Nitrogen-Doped Activated Carbon Supported Pd Catalyst for Hydrodechlorination of 2,4-Dichlorophenol or Chloropentafluoroethane

Molecules ◽

10.3390/molecules24040674 ◽

2019 ◽

Vol 24 (4) ◽

pp. 674 ◽

Cited By ~ 2

Author(s):

Haodong Tang ◽

Bin Xu ◽

Meng Xiang ◽

Xinxin Chen ◽

Yao Wang ◽

...

Keyword(s):

Activated Carbon ◽

Liquid Phase ◽

Gas Phase ◽

Nitrogen Doping ◽

Catalyst Surface ◽

Catalytic Performance ◽

Atomic Ratio ◽

Pd Catalyst ◽

Nitrogen Doped ◽

The Stability

Nitrogen-doped activated carbon (N-AC) obtained through the thermal treatment of a mixture of HNO3-pretreated activated carbon (AC) and urea under N2 atmosphere at 600 °C was used as the carrier of Pd catalyst for both liquid-phase hydrodechlorination of 2,4-dichlorophenol (2,4-DCP) and gas-phase hydrodechlorination of chloropentafluoroethane (R-115). The effects of nitrogen doping on the dispersion and stability of Pd, atomic ratio of Pd/Pd2+ on the surface of the catalyzer, the catalyst’s hydrodechlorination activity, as well as the stability of N species in two different reaction systems were investigated. Our results suggest that, despite no improvement in the dispersion of Pd, nitrogen doping may significantly raise the atomic ratio of Pd/Pd2+ on the catalyst surface, with a value of 1.2 on Pd/AC but 2.2 on Pd/N-AC. Three types of N species, namely graphitic, pyridinic, and pyrrolic nitrogen, were observed on the surface of Pd/N-AC, and graphitic nitrogen was stable in both liquid-phase hydrodechlorination of 2,4-DCP and gas-phase hydrodechlorination of R-115, with pyridinic and pyrrolic nitrogen being unstable during gas-phase hydrodechlorination of R-115. As a result, the average size of Pd nanocrystals on Pd/N-AC was almost kept unchanged after liquid-phase hydrodechlorination of 2,4-DCP, whereas crystal growth of Pd was clearly observed on Pd/N-AC after gas-phase hydrodechlorination of R-115. The activity test revealed that Pd/N-AC exhibited a much better performance than Pd/AC in liquid-phase hydrodechlorination of 2,4-DCP, probably due to the enhanced stability of Pd exposed to the environment resulting from nitrogen doping as suggested by the higher atomic ratio of Pd/Pd2+ on the catalyst surface. In the gas-phase hydrodechlorination of R-115, however, a more rapid deactivation phenomenon occurred on Pd/N-AC than on Pd/AC despite a higher activity initially observed on Pd/N-AC, hinting that the stability of pyridinic and pyrrolic nitrogen plays an important role in the determination of catalytic performance of Pd/N-AC.

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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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