Liquid-phase Selective Hydrogenation of Phenylacetylene on Palladium Nanoparticles Supported on Mesoporous Silica PDF Download
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Author:
Publisher:
ISBN:
Category : Palladium
Languages : en
Pages : 150
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Book Description
A series of palladium catalysts with ca. 1 wt% palladium supported on mesoporous silica with different pore sizes (MCM-41, SBA-15, and MCF) were prepared by deposition of colloidal Pd nanoparticles (Pd/X_col) and Pd(II)acetate solution (Pd/X_imp). MCM-41 and SBA-15 showed the XRD characteristic peaks indicating highly ordered hexagonal pore structure while MCF consisted of spherical cell and frame structure with average pore size of 2.7, 3.9, and 7.8 nm, respectively. Sizes of the colloidal Pd nanoparticles were about 2.3 nm. The supports pore structure did not affect the Pd particle size of Pd/X_col catalysts. For the Pd/X_imp, the Pd particle size was increased with increasing pore diameter of the supports. However, the largest Pd particle size was obtained on Pd/SBA-15_imp since the Pd particles were formed in a long cylindrical shape similar to SBA-15. The Pd/SBA-15_col exhibited the best catalyst performance in the liquid-phase selective hydrogenation of phenylacetylene under mild conditions (40 degress celsius, H2 pressure = 1-5 bar, 30 min). The appropriated pore structure and pore size of SBA-15 could provide a better encapsulation of Pd particles so that high styrene selectivity was attained at complete conversion of phenylacetylene. All the Pd/X_col catalysts exhibited no change in the catalyst activities/selectivity during the recyclability test for four cycles while the Pd/X_imp showed an increase of catalyst activity and lower styrene selectivity in some cases.
Author:
Publisher:
ISBN:
Category : Palladium
Languages : en
Pages : 150
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Book Description
A series of palladium catalysts with ca. 1 wt% palladium supported on mesoporous silica with different pore sizes (MCM-41, SBA-15, and MCF) were prepared by deposition of colloidal Pd nanoparticles (Pd/X_col) and Pd(II)acetate solution (Pd/X_imp). MCM-41 and SBA-15 showed the XRD characteristic peaks indicating highly ordered hexagonal pore structure while MCF consisted of spherical cell and frame structure with average pore size of 2.7, 3.9, and 7.8 nm, respectively. Sizes of the colloidal Pd nanoparticles were about 2.3 nm. The supports pore structure did not affect the Pd particle size of Pd/X_col catalysts. For the Pd/X_imp, the Pd particle size was increased with increasing pore diameter of the supports. However, the largest Pd particle size was obtained on Pd/SBA-15_imp since the Pd particles were formed in a long cylindrical shape similar to SBA-15. The Pd/SBA-15_col exhibited the best catalyst performance in the liquid-phase selective hydrogenation of phenylacetylene under mild conditions (40 degress celsius, H2 pressure = 1-5 bar, 30 min). The appropriated pore structure and pore size of SBA-15 could provide a better encapsulation of Pd particles so that high styrene selectivity was attained at complete conversion of phenylacetylene. All the Pd/X_col catalysts exhibited no change in the catalyst activities/selectivity during the recyclability test for four cycles while the Pd/X_imp showed an increase of catalyst activity and lower styrene selectivity in some cases.
Author: Douglas M. Dolan
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Book Description
Author: Jie S. Zhu
Publisher:
ISBN: 9781085564441
Category : Alkenes
Languages : en
Pages : 45
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Book Description
Abstract: The reactions of palladium are invaluable to modern academic and industrial research, and nanotechnology is the foundation on which the next generation of materials is built upon. Unsupported thiolate-capped palladium nanoparticles were found to be highly substrate selective for alkene hydrogenation and isomerization. A modified Brust-Schiffrin reaction enabled the facile and convenient synthesis of a diverse set of ultra-small thiolate-capped nanoparticles. The physical properties of these nanoparticles were highly tunable due to the widespread availability of ligand precursors. Mechanistic evidence and insights reveal that steric and electronic effects from the ligand environment on the nanoparticle surface controlled reactivity by influencing alkene adsorption via [pi] bond coordination or di-[sigma] bond formation. Only alkenes close enough to the metal surface of the nanoparticles underwent reaction. Dienes with good overlapping p orbitals could overcome these steric effects on the deactivated palladium nanoparticle surfaces. A mechanistic model was built from these completed studies, and this model can be used to predict the selectivity of hydrogenation or isomerization in multiple classes of alkenes with varied substitution patterns. These palladium nanoparticles were also found to be capable of chemoselective alkene hydrogenation in the presence of functional groups that are known to be labile towards reduction by palladium.
Author: Mark E. Davis
Publisher:
ISBN:
Category : SCIENCE
Languages : en
Pages : 432
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Book Description
Discusses recent research and provides tutorial chapters on enhancing selectivity in catalysis through stereoselectivity, reaction pathway control, shape selectivity, and alloys and clusters. Presents an interdisciplinary approach to increasing selectivity in homogeneous and heterogeneous catalysis research. Includes an overview chapter that discusses the current state of the field and offers a perspective on future directions.
Author: Kristine Jang
Publisher:
ISBN:
Category : Acetylene
Languages : en
Pages : 142
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Book Description
Author: Michael Walker
Publisher:
ISBN:
Category : University of Ottawa theses
Languages : en
Pages :
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Book Description
The removal of trace amounts of acetylene in ethylene streams is a high-volume industrial process that must possess high selectivity of alkyne hydrogenation over hydrogenation of alkenes. Current technology uses metallic nanoparticles, typically palladium or platinum, for acetylene removal. However, problems arise due to the deactivation of the catalysts at high temperatures as well as low selectivities at high conversions. Pore expanded MCM-41 is synthesized via a two-step strategy in which MCM-41 was prepared via cetyltrimethylammonium bromide (CTMABr) followed by the hydrothermal treatment with N,N-dimethyldecylamine (DMDA). This material was washed with ethanol to remove DMDA, or calcined to remove both surfactants. PE-MCM-41 based materials were impregnated with palladium, gold, and palladium-gold nanoparticles. The removal of DMDA had an effect on both the conversion and selectivity, in which they were found to drop significantly. However, by using the bimetallic PdAu catalysts, higher selectivity could be achieved due to increased electron density.
Author: Karine Philippot
Publisher: John Wiley & Sons
ISBN: 3527346074
Category : Technology & Engineering
Languages : en
Pages : 384
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Book Description
Nanoparticles in Catalysis Discover an essential overview of recent advances and trends in nanoparticle catalysis Catalysis in the presence of metal nanoparticles is an important and rapidly developing research field at the frontier of homogeneous and heterogeneous catalysis. In Nanoparticles in Catalysis, accomplished chemists and authors Karine Philippot and Alain Roucoux deliver a comprehensive guide to the key aspects of nanoparticle catalysis, ranging from synthesis, activation methodology, characterization, and theoretical modeling, to application in important catalytic reactions, like hydrogen production and biomass conversion. The book offers readers a review of modern and efficient tools for the synthesis of nanoparticles in solution or onto supports. It emphasizes the application of metal nanoparticles in important catalytic reactions and includes chapters on activation methodology and supported nanoclusters. Written by an international team of leading voices in the field, Nanoparticles in Catalysis is an indispensable resource for researchers and professionals in academia and industry alike. Readers will also benefit from the inclusion of: A thorough introduction to New Trends in the Design of Metal Nanoparticles and Derived Nanomaterials for Catalysis An exploration of Dynamic Catalysis and the Interface Between Molecular and Heterogeneous Catalysts A practical discussion of Metal Nanoparticles in Water: A Relevant Toolbox for Green Catalysis Organometallic Metal Nanoparticles for Catalysis A concise treatment of the opportunities and challenges of CO2 Hydrogenation to Oxygenated Chemicals Over Supported Nanoparticle Catalysts Perfect for catalytic, organic, inorganic, and physical chemists, Nanoparticles in Catalysis will also earn a place in the libraries of chemists working with organometallics and materials scientists seeking a one-stop resource with expert knowledge on the synthesis and characterization of nanoparticle catalysis.
Author: Ting Zhou
Publisher:
ISBN:
Category : Acetylene
Languages : en
Pages : 164
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Book Description
Author:
Publisher:
ISBN: 9789745313880
Category : Acetylene
Languages : en
Pages :
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Book Description
Author: Rafael Luque
Publisher: Royal Society of Chemistry
ISBN: 1849734283
Category : Nature
Languages : en
Pages : 243
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Book Description
This timely publication bridges and presents the latest trends and updates in three hot topics of current and future society: nanomaterials, energy and environment. It provides the state-of-the-art as well as current challenges and advances in the sustainable preparation of metal nanoparticles and their applications. The book fills a critical gap in a multidisciplinary area of high economic, social and environmental importance. Currently, there are no books published that deal with these ever increasing important topics, as most books in this area focus on a particular topic (eg. nanomaterials or catalysis or energy or environment). This is the first multidisciplinary edited book covering the very basics to the more advanced, trendy developments, containing a unique blend of nano, green, renewable and bio.
