| 1. |
- Carlson, Johan E., et al.
(författare)
-
Estimation of dielectric properties of crude oils based on IR spectroscopy
- 2014
-
Ingår i: Chemometrics and Intelligent Laboratory Systems. - : Elsevier BV. - 0169-7439 .- 1873-3239. ; 139, s. 1-5
-
Tidskriftsartikel (refereegranskat)abstract
- Dielectric properties of crude oils play an important role in characterization and quality control. Measuring permittivity accurately over a wide range of frequencies is, however, a time-consuming task and existing measurement methods are not easily adapted for real-time diagnostics. IR spectroscopy, on the other hand, provides rapid measurements of fundamental molecular properties.In this paper we show that by using multivariate calibration tools such as PLS regression, it is possible to extract dielectric properties of crude oils directly from IR spectra, in addition to conventional interpretation of the spectra, hence reducing the need for direct electrical measurements. Results on 16 different oil samples show that the dielectric parameters obtained with the proposed method agree well with those obtained using direct permittivity measurements. The PLS regression method has also been extended with Monte-Carlo simulation capabilities to account for uncertainties in the data
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Gellerstedt, Göran, et al.
(författare)
-
Chemical Structures Present in Biofuel Obtained from Lignin
- 2008
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 22:6, s. 4240-4244
-
Tidskriftsartikel (refereegranskat)abstract
- Technical lignins from various sources can be converted into bio-oil with a low O/C ratio by pyrolysis in the presence of formic acid and an alcohol. By application of different analytical techniques, such as Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS), and size-exclusion chromatography (SEC), it has been shown that a complete degradation of the lignin takes place irrespective of the origin. The resulting bio-oil has a low-molecular-mass distribution with a preponderance of aliphatic hydrocarbon structures. A substantial number of phenolic compounds are, however, also present, and some of these also contain carboxyl groups. The results clearly show that formic acid is a powerful supplier of atomic hydrogen. By further optimization of the pyrolysis reaction, it should be possible to further reduce the content of aromatic structures.
|
|
| 5. |
- Ghoreishi, Solmaz, et al.
(författare)
-
Identification and quantification of valuable platform chemicals in aqueous product streams from a preliminary study of a large pilot-scale steam explosion of woody biomass using quantitative nuclear magnetic resonance spectroscopy
- 2024
-
Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media Deutschland GmbH. - 2190-6815 .- 2190-6823. ; 14, s. 3331-
-
Tidskriftsartikel (refereegranskat)abstract
- Steam explosion breaks down the polymeric matrix and enables the recovery of valuable compounds from lignocellulosic feedstock. In the steam explosion process, biomass is treated with high-pressure steam which subsequently generates large quantities of a condensed aqueous liquid (process effluent) and a filtered aqueous liquid (filtrate) that contain furfural, 5-hydroxymethylfurfural, 5-methylfurfural, methanol, and acetic acid as major constituents. This study addresses the identification and quantification of value-added chemicals in the aqueous product streams using quantitative analytical nuclear magnetic resonance spectroscopy with water suppression. This work reports a screening study for two different types of sawdust (Norway spruce and birch) at two different scales (4 L and 10 L reactors) using different reaction temperatures (190–223 °C) and corresponding pressures (13–24 bar), with and without the addition of SO2 gas. The duration of all experiments was 8 min. The process effluents contained acetic acid, methanol, formic acid, 5-methylfurfural, and furfural. Acetic acid (0.5 g/kg dry input biomass) and furfural (1.0 g/kg dry input biomass) were more abundant than methanol, formic acid, and 5-methylfurfural for both feedstocks. The addition of SO2 increased the furfural yields, indicating more efficient hydrolysis of hemicelluloses under acidic conditions. Filtrate samples also contained 5-hydroxymethylfurfural, with the highest concentrations (5.7–6.0 g/kg dry input biomass) in the filtrates from spruce. The different feedstocks and steam explosion temperatures strongly influenced the overall yields of the target compounds, in some cases tripling the concentrations. The results can be used to improve the profit margins in a pellets and chemicals biorefinery, as demonstrated in the ArbaOne pellets plant. © 2022, The Author(s).
|
|
| 6. |
- Hao, Wenming, et al.
(författare)
-
High-Performance Magnetic Activated Carbon from Solid Waste from Lignin Conversion Processes. 1. Their Use As Adsorbents for CO2
- 2017
-
Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 5:4, s. 3087-3095
-
Tidskriftsartikel (refereegranskat)abstract
- Lignin is naturally abundant and a renewable [GRAPHICS] precursor with the potential to be used in the production of both chemicals and materials. As many lignin conversion processes suffer from a significant production of solid wastes in the form of hydrochars, this study focused on transforming hydrochars into magnetic activated carbons (MAC). The hydrochars were produced via hydrothermal treatment of lignins together with formic acid. The activation of the hydrochars was performed chemically with KOH with a focus on the optimization of the MACs as adsorbents for CO2. MACs are potentially relevant to carbon capture and storage (CCS) and gas purification processes. In general, the MACs had high specific surface areas (up to 2875 m(2)/g), high specific pore volumes, and CO2 adsorption capacities of up to 6.0 mmol/g (I atm, 0 degrees C). The textual properties of the MACs depended on the temperature of the activation. MACs activated at a temperature of 700 degrees C had very high ultramicropore volumes, which are relevant for potential adsorption-driven separation of CO2 from N-2. Activation at 800 degrees C led to MACs with larger pores and very high specific surface areas. This temperature-dependent optimization option, combined with the magnetic properties, provided numerous potential applications of the MACs besides those of CCS. The hydrochar was derived from eucalyptus lignin, and the corresponding MACs displayed soft magnetic behavior with coercivities of <100 Oe and saturation magnetization values of 1-10 emu/g.
|
|
| 7. |
- Hermundsgård, Dag Helge, et al.
(författare)
-
Investigating solids present in the aqueous stream during STEX condensate upgrading—a case study
- 2022
-
Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media Deutschland GmbH. - 2190-6815 .- 2190-6823.
-
Tidskriftsartikel (refereegranskat)abstract
- Steam explosion (STEX) of woody biomass is an efficient pretreatment method in the production of water-resistant wood pellets. The STEX process also generates an aqueous condensate stream containing dissolved organic compounds, with furfural as the most abundant and valuable component. An industrial-scale recovery process for furfural and other organic by-products is therefore in the process of being developed and built. One challenge in the process has turned out to be the formation of solid particulate matter that can clog filters in the process unit. We have analyzed both the solid deposits and the fluids present at different points in the process unit to try to identify the origin of the particles using spectroscopic and chromatographic analysis, elemental analysis, and scanning electron microscopy. The aqueous fluids deriving from condensed steam contain furfural and other small organic molecules, with a separate low-density organic layer occurring at some points. This layer largely consists of wood extractives, typically terpenoids. In addition, a heavy organic phase comprising mostly furfural was found at one sampling point. The particles comprise a black, largely insoluble material with a H/C ratio of 0.88 and an O/C ratio of 0.26 and a very low ash content. IR spectra show a low content of C–H functional groups, and chromatographic analysis supports an interpretation that the particles are dominantly furfural-sourced humin-like polymers with adsorbed or co-polymerized terpenoids. Particle formation has been reproduced in a laboratory setting with conditions similar to those in the full-scale process. © 2022, The Author(s).
|
|
| 8. |
- Oregui-Bengoechea, Mikel, et al.
(författare)
-
High-Performance Magnetic Activated Carbon from Solid Waste from Lignin Conversion Processes. 2. Their Use as NiMo Catalyst Supports for Lignin Conversion
- 2017
-
Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 5:12, s. 11226-11237
-
Tidskriftsartikel (refereegranskat)abstract
- Lignin conversion processes produce carbon-rich residues [Oregui-Bengoechea et al. J. Anal. Appl. Pyrolysis 2015, 113, 713-722; Zakzeski et al. Chem. Rev. 2010, 110, 3552-3599] that can be converted into valuable materials such as magnetic activated carbons (MACs). Such lignin derived MACs can be further used as functional substrates for hydrotreating NiMo catalysts. In this work, we studied the activity of different NiMo-MACs for the catalytic conversion of lignin in a formic acid/ethanol media (lignin-to-liquid, LtL, process). Two KOH-activated LtL hydrochars from eucalyptus (MACE) and Norwegian spruce (MACS) lignins were used as catalyst supports. In addition, the activity of the resulting NiMo-MACs, namely, C-MACE and C-MACS, was compared with a NiMo catalyst supported on a commercial activated carbon (AC). At reaction conditions of 340 degrees C and 6 h, the best result was obtained for the NiMo-MACS with a yield of 72.2 wt % of oil and 21.1 wt % of organic solids. At 300 degrees C and 10 h, both NiMo-MAC catalysts displayed higher hydrodeoxygenation (HDO) activities than their commercial counterpart, yielding considerably higher oil yields. The higher HDO activities are tentatively assigned to the formation of NiFe species on the catalytic surfaces of the NiMo-MAC catalysts. In addition, the magnetism exhibited by the C-MACS made it easy to recover the catalyst. However, a considerable loss of activity was observed upon recycling due to a chemical modification of the catalyst surface.
|
|
| 9. |
|
|
