Glycerol is an attractive bio-based platform chemical that can be converted to a variety of bio-based chemicals. We here report a catalytic co-conversion strategy where glycerol in combination with a second (bio-)feed (fatty acids, alcohols, alkanes) is used for the production of bio-based aromatics (BTX). Experiments were performed in a fixed bed reactor (10 g catalyst loading and WHSV of (co-)feed of 1 h-1) at 550 °C using a technical H-ZSM-5/Al2O3 catalyst. Synergistic effects of the co-feeding on the peak BTX carbon yield, product selectivity, total BTX productivity, catalyst life-time, and catalyst regenerability were observed and quantified. Best results were obtained for the co-conversion of glycerol and oleic acid (45/55 wt%), showing a peak BTX carbon yield of 26.7 C%. The distribution of C and H of the individual co-feeds in the BTX product was investigated using an integrated fast pyrolysis-GC-Orbitrap MS unit, showing that the aromatics are formed from both glycerol and the co-feed. The results of this study may be used to develop optimized co-feeding strategies for BTX formation. This journal is
The catalytic conversion of oleic acid to aromatics (benzene, toluene, and xylenes, BTX) over a granular H-ZSM-5/Al2O3 catalyst (ϕ 1.2–1.8 mm, 10 g loading) was investigated in a continuous bench-scale fixed-bed reactor (10 g oleic acid h–1). A peak carbon yield of aromatics of 27.4% was obtained at a catalyst bed temperature of 550 °C and atmospheric pressure. BTX was the major aromatics formed (peak carbon yield was 22.7%), and a total BTX production of 1000 mg g–1 catalyst was achieved within a catalyst lifetime of 6.5 h for the fresh catalyst. The catalyst was deactivated due to severe coke deposition (ca. 22.1 wt % on the catalyst). The used catalyst was reactivated by an ex situ oxidative regeneration at 680 °C in air for 12 h. The regenerated catalyst was subsequently recycled, and in total, 7 cycles of reaction-regeneration were performed. A gradual decrease in the peak carbon yield of BTX was observed with reaction-regeneration cycles (e.g., to 16.3% for the catalyst regenerated for 6 times). However, the catalyst lifetime was remarkably prolonged (e.g., >24 h), leading to a significantly enhanced total BTX production (e.g., 3000 mg g–1 catalyst in 24 h). The fresh, used, and regenerated catalysts were characterized by N2 and Ar physisorption, XRD, HR-TEM-EDX, 27Al, and 29Si MAS ssNMR, NH3-TPD, TGA, and CHN elemental analysis. Negligible changes in textural properties, crystalline structure, and framework occurred after one reaction-regeneration cycle, except for a slight decrease in acidity. However, dealumination of the H-ZSM-5 framework was observed after 7 cycles of reaction-regeneration, leading to a decrease in microporosity, crystallinity, and acidity. Apparently, these changes are not detrimental for catalyst activity, and actually, the lifetime of the catalyst increases, rationalized by considering that coke formation rates are retarded when the acidity is reduced.
The use of H-ZSM-5 with various binders (Al2O3, SiO2, and kaolinite, 10 wt% on catalyst formulation) for the catalytic conversion of glycerol to bio-based aromatics (GTA) was investigated in a continuous bench-scale unit at a pyrolysis temperature of 450 °C, catalytic upgrading temperature of 500 °C, WHSV of pure glycerol of 1 h−1, and atmospheric pressure, and their performance was compared to H-ZSM-5 (SiO2/Al2O3 molar ratio of 28). The latter gave a peak BTX carbon yield of ca. 31.1C.%, a life-time of ca. 220 min, and a total BTX productivity of ca. 312 mg BTX g−1H-ZSM-5. The introduction of binders affects catalyst performance, which is the most profound and promising for the H-ZSM-5/Al2O3 catalyst. It shows a prolonged catalyst life-time of ca. 320 min and a higher total BTX productivity of ca. 518 mg BTX g−1H-ZSM-5, compared to the H-ZSM-5 without a binder. Catalyst characterization studies show that the addition of the binder does not have a major effect on the specific surface area, total pore volume, and total acidity. Other relevant properties were affected, though, such as micropore volume (SiO2), a reduced Brønsted acidity (Al2O3, and SiO2), and reduced crystallinity (SiO2). Coke formation causes severe catalyst deactivation, ultimately leading to an inactive catalyst for BTX formation. Catalyst characterization studies after an oxidative regeneration showed that the textural properties of the regenerated catalysts were close to those of the original catalysts. However, some dealumination of H-ZSM-5 occurs, resulting in decreased crystallinity and acidity, causing irreversible deactivation, which needs attention in future catalyst development studies.
Paper sludge contains papermaking mineral additives and fibers, which could be reused or recycled, thus enhancing the circularity. One of the promising technologies is the fast pyrolysis of paper sludge, which is capable of recovering > 99 wt.% of the fine minerals in the paper sludge and also affording a bio-liquid. The fine minerals (e.g., ‘circular’ CaCO3) can be reused as filler in consumer products thereby reducing the required primary resources. However, the bio-liquid has a lower quality compared to fossil fuels, and only a limited application, e.g., for heat generation, has been applied. This could be significantly improved by catalytic upgrading of the fast pyrolysis vapor, known as an ex-situ catalytic pyrolysis approach. We have recently found that a high-quality bio-oil (mainly ‘bio-based’ paraffins and low-molecular-weight aromatics, carbon yield of 21%, and HHV of 41.1 MJ kg-1) was produced (Chem. Eng. J., 420 (2021), 129714). Nevertheless, catalyst deactivation occurred after a few hours’ of reaction. As such, catalyst stability and regenerability are of research interest and also of high relevance for industrial implementation. This project aims to study the potential of the add-on catalytic upgrading step to the industrial fast pyrolysis of paper sludge process. One important performance metric for sustainable catalysis in the industry is the level of catalyst consumption (kgcat tprod-1) for catalytic pyrolysis of paper sludge. Another important research topic is to establish the correlation between yield and selectivity of the bio-chemicals and the catalyst characteristics. For this, different types of catalysts (e.g., FCC-type E-Cat) will be tested and several reaction-regeneration cycles will be performed. These studies will determine under which conditions catalytic fast pyrolysis of paper sludge is technically and economically viable.
In the context of sustainability, the use of biocatalysis in organic synthesis is increasingly observed as an essential tool towards a modern and ‘green’ chemical industry. However, the lack of a diverse set of commercially available enzymes with a broad selectivity toward industrially-relevant substrates keeps hampering the widespread implementation of biocatalysis. Aminoverse B.V. aims to contribute to this challenge by developing enzymatic screening kits and identifying novel enzyme families with significant potential for biocatalysis. One of the most important, yet notoriously challenging reaction in organic synthesis is site-selective functionalization (e.g. hydroxylation) of inert C-H bonds. Interestingly, Fe(II)/α-ketoglutarate-dependent oxygenases (KGOs) have been found to perform C-H hydroxylation, as well as other oxyfunctionalization, spontaneously in nature. However, as KGOs are not commercially available, or even extensively studied in this context, their potential is not readily accessible to the chemical industry. This project aims to demonstrate the potential of KGOs in biocatalysis. In order to achieve this, the following challenges will be addressed: i) establishing an enzymatic screening methodology to study the activity and selectivity of recombinant KGOs towards industrially relevant substrates, ii) establishing analytical methods to characterize KGO-catalyzed substrate conversion and product formation. Eventually, the proof-of-principle demonstrated during this project will allow Aminoverse B.V. to develop a commercial biocatalysis kit comprised of KGO enzymes with a diverse activity profile, allowing their application in the sustainable production of either commodity, fine or speciality chemicals. The project consortium is composed of: i) Aminoverse B.V, a start-up company dedicated to facilitate chemical partners towards implementing biocatalysis in their chemical processes, and ii) Zuyd University, which will link Aminoverse B.V. with students and (bio)chemical professionals in creating a novel collaboration which will not only stimulate the development of (bio)chemical students, but also the translation of academic knowledge on KGOs towards a feasible biocatalytic application.
