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Patricia J. Kooyman

University of Cape Town

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Éric Prouzet

University of Waterloo

Emiel J. M. Hensen

Eindhoven University of Technology

Rutger A. van Santen

Eindhoven University of Technology

Stig Helveg

Technical University of Denmark

J.F. Creemer

Delft University of Technology

G. Marien Bremmer

Leiden University

H.W. Zandbergen

Delft University of Technology

H. van Bekkum

Delft University of Technology

Søren B. Vendelbo

Danish Technological Institute

A.D. van Langeveld

Delft University of Technology

Cooperative Institutions

Delft University of Technology

Centre National de la Recherche Scientifique

Eindhoven University of Technology

Institute of Catalysis and Petrochemistry

Utrecht University

École Nationale Supérieure de Chimie de Montpellier

Leiden University

Université de Montpellier

University of Cape Town

University of Amsterdam

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The Influence of pH on the Structure of Templated Mesoporous Silicas Prepared from Sodium Metasilicate

Collection of Czechoslovak Chemical Communications (2001)

Patricia J. Kooyman Markéta Slabová V. Bosáček Jiřı́ Čejka Jiřı́ Rathouský

A recently developed homogeneous precipitation method was used for the investigation of the influence of pH on the structure of mesoporous silicas prepared from sodium metasilicate in the presence of a quaternary alkyl ammonium surfactant as a structure directing agent. The rate of pH decrease affects the assembly of mesoscopically ordered composites and, consequently, the porous structure of mesoporous silicas prepared from them by calcination. Pure MCM-41 molecular sieve was prepared by controlling the pH decrease of the reaction mixture so as to achieve the final pH 7.8. The as-made material prepared at higher pH (final value 10.1) is characterized by a lower degree of silica polycondensation. Due to the shrinkage of this material during calcination, a less well-ordered silica with extraordinary large surface area was prepared. A large decrease in pH (final value 5.2) led to non-organized polycondensation of silica species besides the organized assembly of the ordered material, which resulted in the formation of silica with a bimodal mesoporous structure.

MCM-41

10.1135/cccc20010555

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In situ TEM observation of the Boudouard reaction: multi-layered graphene formation from CO on cobalt nanoparticles at atmospheric pressure

Faraday Discussions (2016)

G. Marien Bremmer Eirini Zacharaki Anja O. Sjåstad Violeta Navarro J.W.M. Frenken

Using a MEMS nanoreactor in combination with a specially designed in situ Transmission Electron Microscope (TEM) holder and gas supply system, we imaged the formation of multiple layers of graphene encapsulating a cobalt nanoparticle, at 1 bar CO : N₂ (1 : 1) and 500 °C. The cobalt nanoparticle was imaged live in a TEM during the Boudouard reaction. The in situ/operando TEM studies give insight into the behaviour of the catalyst at the nanometer-scale, under industrially relevant conditions. When switching from Fischer–Tropsch syngas conditions (CO : H₂ : N₂ 1 : 2 : 3 at 1 bar) to CO-rich conditions (CO : N₂ 1 : 1 at 1 bar), we observed the formation of multi-layered graphene on Co nanoparticles at 500 °C. Due to the high temperature, the surface of the Co nanoparticles facilitated the Boudouard reaction, causing CO dissociation and the formation of layers of graphene. After the formation of the first patches of graphene at the surface of the nanoparticle, more and more layers grew over the course of about 40 minutes. In its final state, around 10 layers of carbon capped the nanoparticle. During this process, the carbon shell caused mechanical stress in the nanoparticle, inducing permanent deformation.

Nanoreactor

Carbon fibers

10.1039/c6fd00185h

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Synthesis of large pore silica with a narrow pore size distribution

Microporous and Mesoporous Materials (2001)

Benedikt Lindlar Andreas Kogelbauer Patricia J. Kooyman R. Prins

Mesitylene

Specific surface area

10.1016/s1387-1811(01)00172-x

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A Study on Titanium-Silicalite-1 and Related Systems

Patricia J. Kooyman

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Citations (1)

Characterization of ex Situ Presulfided Ni/Al2O3 Catalysts for Pyrolysis Gasoline Hydrogenation

Journal of Catalysis (2002)

B.W Hoffer François Devred Patricia J. Kooyman A.D. van Langeveld Raimond L.C. Bonné

Sulfidation

Temperature-programmed reduction

Polysulfide

10.1006/jcat.2002.3633

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Citations (22)

Influence of support ionicity on the hydrogen chemisorption of Pt particles dispersed in Y zeolite: consequences for Pt particle size determination using the H/M method

Journal of Catalysis (2005)

Yong Ji A VANDEREERDEN V KOOT Patricia J. Kooyman Johannes D. Meeldijk

Chemisorption

10.1016/j.jcat.2005.06.030

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Effect of ultrasound in enantioselective hydrogenation of 1-phenyl-1,2-propanedione: comparison of catalyst activation, solvents and supports

Ultrasonics Sonochemistry (2004)

B. Toukoniitty Esa Toukoniitty Päivi Mäki‐Arvela Jyri‐Pekka Mikkola Tapio Salmi

Sonication

Cinchonidine

Mesitylene

Sonochemistry

10.1016/j.ultsonch.2004.11.001

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Ultrafiltration Membrane Made with Mesoporous MSU-X Silica

Chemistry of Materials (2003)

Cédric Boissière Marco Antônio Utrera Martines Patricia J. Kooyman T.R. de Kruijff A. Larbot

A new membrane synthesized onto a commercial tubular support was prepared by the directed synthesis of ordered mesoporous MSU-type silica through an interfacial reaction between a silica condensation catalyst (NaF) and new hybrid micellar building units made of silica precursors and nonionic surfactants. This membrane exhibits a specific permeation behavior toward PEO polymers that can be explained by the porosity morphology and silica charge pH dependence.

Ultrafiltration (renal)

Nonionic surfactant

10.1021/cm021319g

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Citations (48)

Cobalt-Based Fischer–Tropsch Synthesis: A Kinetic Evaluation of Metal–Support Interactions Using an Inverse Model System

Catalysts (2019)

Anna P. Petersen Michael Claeys Patricia J. Kooyman Eric van Steen

Metal–support interactions in the cobalt–alumina system are evaluated using an inverse model system generated by impregnating Co3O4 with a solution of aluminum sec-butoxide in n-hexane. This results in the formation of nano-sized alumina islands on the surface of cobalt oxide. The activated model systems were kinetically evaluated for their activity and selectivity in the Fischer–Tropsch synthesis under industrially relevant conditions (220 °C, 20 bar). The kinetic measurements were complemented by H2-chemisorption, CO-TPR, and pyridine TPD. It is shown that the introduction of aluminum in the model system results in the formation of strong acid sites and enhanced CO dissociation, as evidenced in the CO-TPR. The incorporation of aluminum in the model systems led to a strong increase in the activity factor per surface atom of cobalt in the rate expression proposed by Botes et al. (2009). However, the addition of aluminum also resulted in a strong increase in the kinetic inhibition factor. This is accompanied by a strong decrease in the methane selectivity, and an increase in the desired C5+ selectivity. The observed activity and selectivity changes are attributed to the increase in the coverage of the surface with carbon with increasing aluminum content, due to the facilitation of CO dissociation in the presence of Lewis acid sites associated with the alumina islands on the catalytically active material.

Fischer–Tropsch process

Chemisorption

10.3390/catal9100794

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Shape of Cobalt and Platinum Nanoparticles Under a CO Atmosphere: A Combined In Situ TEM and Computational Catalysis Study

ACS Catalysis (2019)

Jenoff E. De Vrieze G. Marien Bremmer Mostafa Aly Violeta Navarro Joris Thybaut

The shape of metal nanoparticles can dramatically depend on reaction conditions. While Pt nanoparticles are known to dynamically respond to the partial pressure of CO, in situ TEM images show that, surprisingly, Co nanoparticles do not change their shape under a CO atmosphere despite going through several reconstructions. Detailed DFT calculations attribute this contrasting behavior to two factors: (1) CO adsorption has a higher stabilization effect on the high-index facets of Pt than on those of Co; (2) the Co surface energy is more sensitive to the coordination number, making high-index surfaces less stable relative to Pt. These two factors combined can affect the stability of high-index surfaces as is the case for Pt nanoparticles, which reconstruct already at low CO pressures. In the case of Co nanoparticles, the low-index surface remains the most stable even at high CO partial pressures. The robustness of the shape of Co nanoparticles challenges recent proposals that high-index facets, which facilitate direct CO dissociation, are present on Co nanoparticle catalysts under Fischer–Tropsch conditions.

Fischer–Tropsch process

10.1021/acscatal.9b01840

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Citations (23)

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