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Dit eindwerk bevat het onderzoek naar en de opbouw van een onderhoudsplan. Dit onderhoudsplan heeft de naam 'emissiemetingen' meegekregen. Het onderhoudsplan omvat een meetprocedure om Janssen Pharmaceutica Geel met een regelmatige frequentie te controleren op het lekken van vluchtige organische componenten aan kranen, flenzen, afdichtingen, kleppen, ... Het eindwerk bestaat in grote delen uit de theoretische achtergrond over emissie en zijn reglementering, het opstellen van het onderhoudsplan en informatie over het meetinstrument. Na dit alles wordt een praktisch voorbeeld aangehaald en worden cijfers en uitbreidingen besproken. Bij de theoretische achtergrond worden de verschillende wetgevingen, meetprocedures, gevaarlijkheid van stoffen, de grenswaarden en het soort onderhoud besproken. Het gedeelte over het onderhoudsplan bevat onderhoudsbepalingen en algemeenheden over het onderhoudsplan. Het meetinstrument wordt ook even aangehaald met zijn werking, mogelijkheden en voor- en nade

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The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field. The chapter "Lignin‑Based Composite Materials for Photocatalysis and Photovoltaics" is available open access under a CC BY 4.0 License via link.springer.com.

Macromolecules --- Organic chemistry --- Environmental protection. Environmental technology --- Chemical technology --- organische chemie --- ecologie --- chemische technologie --- polymeren

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Shifting away from fossil resources constitutes an enormous challenge for our society. For energy purposes, alternatives like wind and solar power are becoming increasingly attractive options. For organic chemicals, materials and fuels, biomass could provide a renewable alternative. In this context, biorefineries are being developed, aimed at converting biomass ultimately into chemicals, materials and fuels.Lignocellulose, the most abundant form of biomass on earth, is an interesting feedstock for a biorefinery. Lignocellulose is the structural element of plant cell walls and consists of three biopolymers, viz. cellulose, hemicellulose and lignin. It is ubiquitous in the plant kingdom (e.g. wood, grasses, shrubs) and also present in residues from agriculture or forestry. As these residues are abundantly available at low cost, they constitute a favorable feedstock for a biorefinery.Tree bark is a major waste stream from wood processing industries, and a source of lignocellulose biomass. Currently, bark is mainly burned for energy recuperation or used as mulch in horticulture. Valorizing bark in a biorefinery thus presents an alluring possibility. In this respect, decent knowledge of the bark feedstock is indispensable. For that reason, the barks of six relevant species, viz. poplar, black locust, red oak, willow, Corsican pine and larch, were thoroughly characterized in this dissertation. Anatomical analysis illustrated the structural heterogeneity and various cell types in the different barks. Chemical compositional analyses highlighted the large differences between species. All barks had a substantial lignocellulose content, however, the fraction of (hemi)cellulosic carbohydrates was low (35-44 wt%). The lignin content was rather high (22-45 wt%), and it was found to have a low S/G ratio for hardwood barks (0.3-0.7), and a G type lignin for softwood barks. The fraction of suberin, an aliphatic polyester, was highest is black locust bark (10 wt%). Besides structural components, the studied barks had a high extractives content (14-30 wt%).As barks generally have a smaller carbohydrate fraction, typical carbohydrate-oriented lignocellulose biorefining strategies (e.g. second generation ethanol, pulp and paper) are less suited for barks. Such lignocellulose biorefining strategies aim at removing lignin as efficiently as possible. However, as lignin is prone to undergo repolymerization reactions, the resulting isolated lignin is highly condensed and unreactive, and thus less suited for further upgrading. To tackle this, lignin-first biorefining strategies that focus on lignin conversion prior to the carbohydrate fraction, have been developed. Such lignin-oriented lignocellulose biorefining could prove very useful for bark valorization, given their typically higher lignin content. One promising example of a lignin-first biorefining strategy is the 'Reductive Catalytic Fractionation' (RCF). In an RCF process, lignocellulose is contacted with an organic solvent (mixture), like methanol, at elevated temperature in presence of an heterogeneous redox catalyst (e.g. Pd/C, Ru/C) in a reducing environment. This effectuates the solvolytic extraction of lignin fragments from the lignocellulose matrix, its further depolymerization and, at the same time, chemical stabilization of the formed intermediates through reductive catalysis. The role of the metal catalyst is hereby crucial, as the reduction of lignin fragments effectively lowers their reactivity towards repolymerization reactions. The outcome of the RCF strategy is thus a low molecular weight lignin oil, amenable for subsequent conversion into chemicals, and a (hemi)cellulose pulp suited for further valorization.In contrast to this reductive strategy (i.e. RCF), also a review of the literature on oxidative lignin conversion was provided. Such oxidative pathways can provide an interesting tool for the formation of highly functionalized, valuable lignin products. The catalytic systems for the oxidative conversion of dimeric lignin model compounds and isolated lignins were summarized and critically discussed. Next, several challenges regarding the substrate, catalyst and operating conditions were highlighted, and a future perspective on lignin oxidation was offered. Finally, comparing reductive and oxidative lignin-first processing illustrated the advantages of the reductive process (i.e. RCF) for bark biorefining.In this dissertation, an evaluation was made of the RCF strategy when using bark as feedstock. First, the bark of black locust (Robinia pseudoacacia) was studied. Given the substantial suberin content in this bark, focus was put on both the lignin and the suberin fraction: RCF enabled the extraction and depolymerization of both biopolymers. The thus obtained oil phase contained lignin-derived phenolic mono-, di- and oligomers, as well as suberin-derived, long-chain (bifunctional) aliphatic monomers. The process severity (i.e. temperature and reaction time) was found to govern the extend of both suberin and lignin depolymerization. Parameters involving catalytic hydrogenation (i.e. catalyst type and loading, H2 pressure) did not influence the suberin depolymerization, but affected the stabilization of the lignin fragments and consequently the phenolic monomer yield. Comparing RCF of black locust bark with black locust wood, revealed the resistance to delignification and the lesser extent of lignin depolymerization in bark.Next, the substrate scope for the RCF biorefinery was expanded by evaluating the barks of ten different species under identical RCF conditions. By using both raw and extractive-free barks, it was found that the extractives minimally affect the lignin conversion. Between different species however, the product outcome varied strongly. The lignin monomer yield ranged from 2 to 19 wt% lignin, with a high selectivity towards 4-n-propanol-subtituted monomers. Next to lignin products, also catechols, resorcinols, pyrogallols and ring-opened flavonoids were observed, likely from the depolymerization of condensed tannins present in barks. Interestingly, the redox catalyst was found to be crucial not only for generating lignin monomers, but also for certain condensed tannins products, notably the ring-opened flavonoids.

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The continuous growth of world’s population and the increasing economic industrialization has led to an ever increasing demand to energy and goods. Simultaneously, we are confronted with a foreseeable depletion of cheap oil and sustainability issues for gas and coal conversion. These facts have stimulated the quest for renewable resources. Perhaps their major role as energy supplier may be questioned on the long term, but renewable feedstock for the manufacture of chemicals is not unrealistic. Keeping or using the original chemical functionality of the bio-based molecules may be advantageous in many cases, especially when the atom economy of the reaction to form the desired product is very high, or, in other words, when waste formation can be neglected. Besides the design and development of novel reaction technologies, chemo- and bio-catalysis will play a major role in that coming feedstock transition.This thesis focuses on the catalytic synthesis of short amines from renewable feedstock. Amines are a group of chemical compounds that contain nitrogen atoms. Their functionality such as polarity and nucleophilicity can be exploited in various ways, which is why they are produced on a large industrial scale. For instance, they are building blocks of polymers, surfactants, pharmaceuticals and agrochemicals, and they are used as CO2 absorbents or as catalysts, for instance for polyurethane synthesis. So far, industrial amines are produced from petrochemical resources like methanol (e.g. in case of MMA, DMA and TMA) and ethylene (e.g. in case of ethanolamines and ethylenediamines). Moreover, their synthesis procedures involve toxic, explosive and/or expensive chemicals and intermediates, therefore not in line with the green chemistry principles of tomorrows chemical industry.In this research, we looked for new, innovative catalytic processes for the safe and efficient production of short amines from carbohydrates. From a chemical point of view, these sugar structures are highly functional and therefore suitable as alternative carbon source for the production of chemicals. The cellulose building block, glucose, for instance contains one oxygen atom per carbon atom, comprising five alcohol groups and one carbonyl functional group. These C-O bonds, especially the carbonyl, are reactive towards a selectively transformation into C-N bonds via the different technologies that are available hereto. Catalysis plays a key role in achieving the reactions’ high selectively. Notwithstanding the undeniable importance of homogeneous catalysis in today’s chemical industry, solid catalysts offer several advantages, when compared to dissolved catalysts. They are separated more easily from the product mixture and allow for continuous processing. This research therefore focused on the exploration of heterogeneous catalytic processes.The first goal was to develop a new reaction route to produce short amines from carbohydrates. This process implies a cleavage of C-C bonds besides the formation of novel C-N bonds. Classic reaction types to split C-C bonds, like retro-aldol condensation and hydrogenolysis, are known to require a high reaction temperature, typically well above 200 °C, which leads to thermal degradation and thus low product selectivity. Inspired by the working mechanism of Aldolase enzymes, an efficient low-temperature chemocatalytic process was therefore developed. This process requires an amine (as the nitrogen source) and a metal catalyst and is carried out under hydrogen pressure at temperatures well below 150 °C. The amine is essential to cleave the C-C bond at the low temperature, while the metal activates hydrogen to hydrogenate unsaturated intermediates. This reductive aminolysis process thus converts reducing sugars efficiently into acyclic ethylenediamines, like N,N,N’,N’-tetramethylethylenediamine (TMEDA), and ethanolamines, like N,N-dimethylaminoethanol (DMAE). It was demonstrated that different primary and secondary amines reagents can be used in this novel catalytic process. The main reaction product was always the corresponding ethylenediamine. Selectivity up to 84% could be achieved at full sugar conversion, even in absence of solvent. As an example, one of the obtained ethylenediamines, viz. N,N’-bis(2-hydroxyethyl)-N,N’-dimethylethylenediamine (BHEDMEDA), was successfully esterified and quaternized. The resulting “diester diquat” surfactant has potential applications as detergent or fabric softener.The second part of this research unraveled the complex mechanism behind the reductive aminolysis process. The reaction mechanism was initially proposed, based on a kinetics and reactivity study and was further validated by a Density Functional Theory (DFT) study. The C-C cleavage that is observed occurs in a controlled fashion and is initiated after electron rearrangement within a zwitterionic iminium intermediate that is formed after nucleophilic amine attack at the reductive sugar end. DFT calculations confirmed that the reaction route involving the amine facilitated C-C scission is energetically the most favorable one. After scission, the commercial redox catalyst ensures an efficient hydrogenation of the resulting reactive, unsaturated retro-aldol fragments into stable short amines. This way, the thermodynamic equilibria are directed towards the desired intermediates and the targeted amines are ultimately obtained with high selectivity. To our delight, a (cheap) commercial silica supported nickel catalyst showed excellent performance to this end. Optimization of the process parameters afforded an excellent ethylenediamine product yield of 92% at full sugar conversion, using the supported nickel catalyst. The reductive aminolysis is impacted by a peculiar solvent effect. The ethylenediamine yield increased significantly when the reductive aminolysis was carried out in methanol instead of tetrahydrofuran. This observation was confirmed by DFT calculations, demonstrating that the presence of methanol considerably lowers the energy barriers of the desired reaction steps, resulting in a faster and thus more selective formation of the desired ethylenediamine product.Reductive aminolysis thus allows for the efficient conversion of reducing sugars into the corresponding ethylenediamine at low temperature. However, the formation of corresponding ethanolamines via a similar mechanism is difficult, since selective enaminol hydrogenation mainly led to the corresponding glucamine, instead of the ethanolamine. The use of stoichiometric amount of the amine reagent on the other hand lowered the selectivity of the process. In the third part of this research, we therefore aimed for the development of an alternative, selective route to produce DMAE from a renewable carbon source, viz. ethylene glycol (EG), by using heterogeneous transition metal (TM) catalysts. DMAE is currently produced on an industrial scale from the reaction of dimethylamine (DMA) with ethylene oxide (EO) for its use as a surfactant building block. There are recent reports that describe excellent progress in the direct synthesis of EG from glucose and even cellulose. This motivates the strategy to produce of DMAE from EG. Recent technologies for the amination of EG as described in research literature use (expensive) homogeneous TM complexes that are difficult to separate from the product mixture. The use of heterogeneous TM catalysts (in the gas phase) mostly requires high reaction temperatures (> 200 °C) in order to activate the unreactive EG substrate. This ultimately results in low selectivity towards the corresponding ethanolamine. This work therefore proposes the use of a base (KOH) to stimulate the dehydrogenation of EG, allowing the conversion of EG into DMAE with high selectivity (94%) at strongly reduced temperature, viz. 150 °C, using a commercial silica-alumina supported nickel catalyst. On top of the facilitation effect on dehydrogenation, the KOH directs the reaction to DMAE at the expense of TMEDA, resulting in the unique selectivity for this base-catalyzed process.