Search

Your search keyword '"De Clercq, Jeriffa"' showing total 161 results
Start Over Author "De Clercq, Jeriffa"
161 results on '"De Clercq, Jeriffa"'

14. Recent advances in amine catalyzed aldol condensations.

Author

Biesemans, Bert, De Clercq, Jeriffa, Stevens, Christian V., Thybaut, Joris W., and Lauwaert, Jeroen

Subjects
*ALDOL condensation, *CATALYST supports, *AMINES, *HETEROGENEOUS catalysis, *HYDROGEN bonding
Abstract

During the past two decades, new insights have driven the development and optimization of aminated materials as aldol condensation catalysts. Amines, either primary or secondary, facilitate the reaction via an enamine mechanism. If the spatial placement with respect to the amine allows it, weak acid sites such as silanols or hydroxyls, can cooperate as hydrogen bond donors and aid in proton transfer steps. Furthermore, the reaction environment, i.e., support and solvent and their mutual interactions, is also a key determining factor. In particular, co-feeding small amounts of water suppresses the formation of inhibiting and site-blocking species. However, silica-based materials are susceptible to hydrolysis. This led to the development of water tolerant (bio)polymer supported amine catalysts which also exhibit selective component enrichment properties, opening up opportunities for further catalyst development. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

21. Insights Into Natural Organic Matter and Its Removal By Ion Exchange Resins

Author

Laforce, Elien, Stals, Ingeborg, Cornelissen, Emile R, Vermeir, Pieter, and De Clercq, Jeriffa

Abstract

Natural organic matter (NOM) is present in all surface and ground waters and originates from degradation and by-products of living organisms and plants. NOM can be separated by HPLC-Organic Carbon Detection into five fractions: biopolymers, humic substances, building blocks, low molecular weight acids and low molecular weight neutrals. Water quality is affected by the presence of NOM (fractions) and moreover it can cause several issues during water treatment processes. Therefore, its removal by a variety of technologies is widely studied. Anion exchange resins (AER) can effectively remove a major part of this NOM, but due to its complex nature, the process is still not completely understood and optimized. In this work, the removal of NOM by macroporous styrenic weak (WBA), strong (SBA) and combined weak/strong (W/SBA) base anion exchange resins is studied. The resins were used in two industrial relevant counter ion forms: the OH- or free base form for SBA and WBA resins respectively, using an NaOH conditioning solution as applied in water demineralisation units and a Cl- form using NaCl for SBA resins and HCl for the WBA and W/SBA resins, as seen in drinking water treatment and Dupont’s recently developed weak basic NOM scavenger resins respectively. The effect of this conditioning on the equilibrium pH and driving forces for NOM removal in batch mode experiments using synthetic water containing model compounds for the different NOM fractions was investigated. This study demonstrated that next to AER resin selection, the conditioning procedure is an important parameter to be considered in the design of NOM removal processes, especially when specific NOM fractions are targeted.

Published
2022
Full Text
View/download PDF

23. Valorizing Kraft Lignin by a Catalytic Reductive Depolymerization in Ethanol/Water with Formic Acid as a Supplementary H2 Donor.

Author

Jacobs, Bram, Van Nieuwenhove, Ine, Lauwaert, Jeroen, De Saegher, Tibo, Gracia-Vitoria, Jaime, Vanbroekhoven, Karolien, Renders, Tom, De Roo, Tony, De Clercq, Jeriffa, and Verberckmoes, An

Abstract

Lignin is a promising biopolymer to serve as a sustainable resource for a multitude of applications (e.g., thermoset materials, production of bulk chemicals) thereby substituting fossil-based carbon sources. In this work, the reductive depolymerization of Kraft lignin (KL) was studied in ethanol/water aided by formic acid (FA) as the way forward to valorize lignin. The effect of various process conditions was elucidated using 31P-NMR, pH, GPC, CHNSO, GC–MS and 2D-LC analyses. It is found that the addition of a small amount of FA (3.6 vol%) is beneficial for obtaining smaller lignin fragments with more phenolic OH (PhOH) functionalities upon depolymerization at 250 °C for 8 h. Besides, a higher FA concentration causes acid catalyzed lignin repolymerization and a longer reaction time results in only a limited reduction in molecular weight of the obtained lignin fragments. The addition of a supported Pd catalyst leads to a more pronounced depolymerization (smaller lignin fragments with more PhOH functionalities) as well as a stronger decrease in oxygen and sulfur content. Furthermore, several experiments and multiple analysis techniques support the hypothesis that FA acts as H2 donor under the investigated conditions in this study. In conclusion, KL (MW ~ 16,436 g mol−1 and 3.31 mmol g−1 PhOH) was successfully depolymerized into a low molecular weight lignin (MW ~ 3250 g mol−1) with more PhOH functionalities (5.29 mmol g−1). [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

28. List of Contributors

Author

Abbasalizadeh, Aida, primary, Aggelatou, Vassiliki, additional, Agioutantis, Zacharias, additional, Altenberger, Uwe, additional, Antrekowitsch, Helmut, additional, Balomenos, Efthymios, additional, Barakos, George, additional, Barnes, Gregory B., additional, Barteková, Eva, additional, Boesche, Nina K., additional, Borges de Lima, Ismar, additional, Bourbos, E., additional, Brell, Maximilian, additional, Davris, Panagiotis, additional, De Canck, Els, additional, De Clercq, Jeriffa, additional, De Decker, Jeroen, additional, Enkhzul, Bayarmagnai, additional, Ferrari, Andrea, additional, Giannopoulou, I., additional, Grundfelt, Bertil, additional, Guo, X., additional, Gutzmer, Jens, additional, Herrmann, Sabrina, additional, Höglund, Lars Olof, additional, Kamenopoulos, Sotiris N., additional, Karantonis, A., additional, Kaya, S., additional, Keith-Roach, Miranda, additional, Kennedy, James C., additional, Komnitsas, Kostas, additional, Körting, Friederike, additional, Kousa, Anne, additional, Laukkanen, Jukka, additional, Leal Filho, Walter, additional, Li, Ling Zhi, additional, Lkhagvasuren, Batzorig, additional, Lubitz, Christin, additional, Luidold, Stefan, additional, Magistrati, Paloma, additional, Mancheri, Nabeel A., additional, Margai, Delgermaa, additional, Mielke, Christian, additional, Mischo, Helmut, additional, Olivieri, Nicolò, additional, Panias, Dimitrios, additional, Papenfuß, Anne, additional, Paspaliaris, Ioannis, additional, Peelman, Sebastiaan, additional, Pohjolainen, Esa, additional, Poscher, Alexander, additional, Prakash, V., additional, Rogass, Christian, additional, Santos, Roberto V., additional, Schnideritsch, Holger, additional, Schønwandt, Hans K., additional, Seetharaman, Seshadri, additional, Shields, Deborah, additional, Sietsma, Jilt, additional, Silveira, Francisco V., additional, Sun, Zhi H.I., additional, Takehara, Lucy, additional, Teng, Lidong, additional, Tonn, Sabine, additional, Topkaya, Y.A., additional, Torppa, Akseli, additional, Ulrich, Thomas, additional, Van Der Voort, Pascal, additional, Yang, Xiaosheng, additional, Yang, Yongxiang, additional, and Zepf, Volker, additional

Published
2016
Full Text
View/download PDF

46. Nanotechnology in catalysis: the force awakens

Author

Van Vaerenbergh, Beau, Lauwaert, Jeroen, De Clercq, Jeriffa, Vermeir, Pieter, and Thybaut, Joris

Subjects
Chemistry, Heterogeneous catalysis, Suzuki reaction, Metal-support interactions, Hydrogen production, Nanotechnology, Nanoparticle size effects
Abstract

Nanotechnology - defined as Key Enabling Technology in Europe - plays an important role in our society, e.g., in medicine, in sports, in water treatment applications, in energy devices and is now also emerging in the field of catalysis. It strongly encompasses research and development to synthesize, control, and manipulate catalytic systems of enhanced or even novel properties. These properties can be attributed to the size of the nanomaterial which is ranged in one or more external dimensions from approximately 1 to 100 nm.

Published
2018

Catalog

Books, media, physical & digital resources
See catalog results