Valorization of humin type byproducts from pyrolytic sugar conversions to biobased chemicals

The pyrolytic sugar fraction, obtained by an aqueous extraction of pyrolysis oil, is an attractive source for sugar-derived platform chemicals. However, solids (humin) formation occurs to a significant extent during hydrolysis and subsequent acid-catalyzed conversion processes. In this study, we report investigations on possible conversion routes (pyrolysis, liquefaction) of such humin byproducts to biobased chemicals. Experiments were carried out with a model humin made from a representative technical pyrolytic sugar and the product was characterized by elemental analysis, GPC, TGA, HPLC, GC-MS, FT-IR and NMR. The obtained humin sample is soluble in organic solvents (dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), and isopropanol (IPA)), in contrast to typical more condensed humins from glucose and fructose, allowing characterization using NMR and GPC. All analyses reveal that the humins are oligomeric in nature (M-w of about 900 g/mol) and consist of sugar and furanic fragments linked with among others (substituted) aliphatic, ester units and, in addition, phenolic fragments with methoxy groups. The humins were used as a feed for catalytic pyrolysis and catalytic liquefaction experiments. Catalytic pyrolysis experiments (mg scale, programmable temperature vaporizer (PTV)-GC-MS, 550 degrees C) with HZSM-5 50 as the catalyst gave benzene-toluene-xylene-naphthalene-ethylbenzene mixtures (BTXNE) in 5.1 wt% yield based on humin intake. Liquefaction experiments (batch reactor, 350 degrees C, 4 h, isopropanol as both the solvent and hydrogen donor and Pt/CeO2 (4.43 wt% Pt) catalyst) resulted in 80 wt% conversion of the humin feed to a product oil with considerable amounts of phenolics and aromatics (ca. 24.7 % based on GC detectables in the humin oil). These findings imply that the techno-economic viability of pyrolysis oil biorefineries can be improved by converting humin type byproducts to high value, low molecular weight biobased chemicals

Measurement of g-factor tensor in a quantum dot and disentanglement of exciton spins

We perform polarization-resolved magneto-optical measurements on single InAsP quantum dots embedded in an InP nanowire. In order to determine all elements of the electron and hole $g$-factor tensors, we measure in magnetic field with different orientations. The results of these measurements are in good agreement with a model based on exchange terms and Zeeman interaction. In our experiment, polarization analysis delivers a powerful tool that not only significantly increases the precision of the measurements, but also enables us to probe the exciton spin state evolution in magnetic fields. We propose a disentangling scheme of heavy-hole exciton spins enabling a measurement of the electron spin $T_2$ time

An improved catalytic pyrolysis concept for renewable aromatics from biomass involving a recycling strategy for co-produced polycyclic aromatic hydrocarbons

Catalytic pyrolysis of crude glycerol over a shaped H-ZSM-5 zeolite catalyst with (partial) recycling of the product oil was studied with the incentive to improve benzene, toluene, and xylene (BTX) yields. Recycling of the polycyclic aromatic hydrocarbon (PAH) fraction, after separation from BTX by distillation and co-feeding with the crude glycerol feed, was shown to have a positive effect on the BTX yield. Further improvements were achieved by hydrogenation of the PAH fraction using a Ru/C catalyst and hydrogen gas prior to co-pyrolysis, and BTX yields up to 16 wt% on feed were obtained. The concept was also shown to be beneficial to other biomass feeds such as e.g., Kraft lignin, cellulose, and Jatropha oil

Single-photon Resolved Cross-Kerr Interaction for Autonomous Stabilization of Photon-number States

Quantum states can be stabilized in the presence of intrinsic and environmental losses by either applying active feedback conditioned on an ancillary system or through reservoir engineering. Reservoir engineering maintains a desired quantum state through a combination of drives and designed entropy evacuation. We propose and implement a quantum reservoir engineering protocol that stabilizes Fock states in a microwave cavity. This protocol is realized with a circuit quantum electrodynamics platform where a Josephson junction provides direct, nonlinear coupling between two superconducting waveguide cavities. The nonlinear coupling results in a single photon resolved cross-Kerr effect between the two cavities enabling a photon number dependent coupling to a lossy environment. The quantum state of the microwave cavity is discussed in terms of a net polarization and is analyzed by a measurement of its steady state Wigner function.Comment: 8 pages, 6 figure

Nanopositioning of a diamond nanocrystal containing a single NV defect center

Precise control over the position of a single quantum object is important for many experiments in quantum science and nanotechnology. We report on a technique for high-accuracy positioning of individual diamond nanocrystals. The positioning is done with a home-built nanomanipulator under real-time scanning electron imaging, yielding an accuracy of a few nanometers. This technique is applied to pick up, move and position a single NV defect center contained in a diamond nanocrystal. We verify that the unique optical and spin properties of the NV center are conserved by the positioning process.Comment: 3 pages, 3 figures; high-resolution version available at http://www.ns.tudelft.nl/q

Deterministic nano-assembly of a coupled quantum emitter - photonic crystal cavity system

The interaction of a single quantum emitter with its environment is a central theme in quantum optics. When placed in highly confined optical fields, such as those created in optical cavities or plasmonic structures, the optical properties of the emitter can change drastically. In particular, photonic crystal (PC) cavities show high quality factors combined with an extremely small mode volume. Efficiently coupling a single quantum emitter to a PC cavity is challenging because of the required positioning accuracy. Here, we demonstrate deterministic coupling of single Nitrogen-Vacancy (NV) centers to high-quality gallium phosphide PC cavities, by deterministically positioning their 50 nm-sized host nanocrystals into the cavity mode maximum with few-nanometer accuracy. The coupling results in a 25-fold enhancement of NV center emission at the cavity wavelength. With this technique, the NV center photoluminescence spectrum can be reshaped allowing for efficient generation of coherent photons, providing new opportunities for quantum science.Comment: 13 pages, 4 figure

Ozone mediated depolymerization and solvolysis of technical lignins under ambient conditions in ethanol

Technical lignins are highly available and inexpensive feedstocks derived from current large scale biomass utilizing industries. Their valorization represents a bottleneck in the development of biorefineries, as the inherently complex lignin structure often suffers severe condensation during isolation, leading to their current application as low value fuel. Processes able to depolymerize technical lignins into value-added (intermediate) molecules are of great interest for the development of integrated, viable routes aiming at the full valorization of lignocellulosic biomass. Here, we report an effective ozone mediated depolymerization of four technical lignins (Indulin-AT Kraft, ball-milled Indulin-AT Kraft, Alcell organosolv and Fabiola organosolv) in ethanol under ambient conditions without the need for catalysts. 52–87 wt% of these nearly ethanol insoluble lignins was broken down into soluble fragments upon ozone exposure. The average molecular weight of the soluble fragments was shown to have decreased by 40–75% compared to the parent materials. A range of (di)carboxylic acids and (di)ethyl esters was identified, accounting for up to 40 wt% of the ozonated lignin oils. These products are the result of phenol ring-opening reactions as well as oxidative cleavage of unsaturated linking motifs followed by partial esterification. Reactivity varied substantially among the lignin feedstocks. For instance, lower particle sizes and higher degradation of the native lignin structure were shown to be beneficial for the effective action of the ozone. Our results show that a straightforward ozonation process under ambient conditions can depolymerize recalcitrant lignins into oxygenated fragments and low molecular weight products soluble in ethanol. These can potentially be used for the synthesis of high-value drop-in chemicals

Biogrondstoffen; van fossiel naar biomassa

Er is een oneindige voorraad planten dankzij de straling van de zon. Er zijn op aarde voldoende grond en biologische afvalstromen beschikbaar om een groot deel van de wereldbehoefte aan energie te vervullen en zo te komen tot een biobased economy. Het cahier Biogrondstoffen beschrijft de mogelijkheden en technieken om biomassa te verkrijgen en om te zetten in bruikbare en commercieel toepasbare biogrondstoffen. Het cahier besteedt ook aandacht aan de belemmeringen voor een dergelijke groene economie. Een duurzame productie van biomassa en biobrandstoffen op grote schaal vereist goede voorwaarden, zodat de omstandigheden van mensen in arme landen en het milieu niet verslechteren, maar juist verbeteren. Met die gedachte en gezien de ontwikkelingen in de technologie, is de redactie van het cahier voorzichtig optimistisch over de toekomst van een groene, mede op biomassa georiënteerde, economie