Valorization of Biogenic and Not Biogenic Residuals/Byproducts from Thermochemical Processes: Diagnostic, Product Characterization, and Emissions Control

A special issue of Fuels (ISSN 2673-3994).

Deadline for manuscript submissions: closed (30 June 2024) | Viewed by 20550

Special Issue Editors


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Guest Editor
Istituto di Scienze e Tecnologie per l’Energia e la Mobilità Sostenibili (STEMS)–CNR–P.le V. Tecchio 80, 80125 Napoli, Italy
Interests: development and application of advanced diagnostic techniques for conventional and non-conventional pollutants; detection of combustion-generated fine and ultra-fine particulate from combustion systems and study of its formation mechanism and chemical-physical structure, strictly linked to its environmental and; characterization of heavy fossil fuels in terms of structure and pollutant emission in order to set-up chemical procedures for obtaining cleaner fuels; restructuring of carbon materials with thermal annealing by furnace and laser heating, and study of the heating-induced structural changes; relation between nanostructural properties and physico-chemical properties of nanocarbons

E-Mail Website
Guest Editor
Istituto di Scienze e Tecnologie per l'Energia e la Mobilità Sostenibili (STEMS)–CNR–P.le V. Tecchio 80, 80125 Napoli, Italy
Interests: catalyst; biomasses; torrefaction; gasification and co-gasification; pyrolysis; combustion; fluidized ad fixed bed reactor; tar abatement; pollution abatement

Special Issue Information

Dear Colleagues,

Energy transition and decarbonization toward cleaner energy require the utilization of new technologies and energy sources. Key issues are diversifying fuels, combining renewable with fossil sources, abatement and/or recovery and valorization of pollutant by-products. 

Thermochemical processes are well assessed approaches for biomass, waste and byproducts valorization, even if formation mechanisms of pollutants in combustion, gasification, and pyrolysis are still open concerns.  

Contributions regarding diagnostics for the study of pollutants formation in thermochemical processes of biogenic and not biogenic residuals/byproducts valorization (combustion, gasification), characterization of process products, strategies for the reduction of emissions as well as integrations of multiple processes or the enhancement of co-processes are issues closely linked to the focus of this Special Issue.

Dr. Barbara Apicella
Dr. Giovanna Ruoppolo
Guest Editors

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Published Papers (7 papers)

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Research

13 pages, 2376 KiB  
Article
CFD Simulation of Hydrogen Sulfide (H2S) Desulfurization Using Ionic Liquids and Graphene Oxide Membrane
by Alon Davidy
Fuels 2023, 4(3), 363-375; https://doi.org/10.3390/fuels4030023 - 4 Sep 2023
Viewed by 2150
Abstract
Hydrogen sulfide (H2S) is considered a toxic and corrosive gas, commonly found in natural gas, crude oil, and other fossil fuels. This corrosive gas may lead to stress corrosion cracking (SCC). This phenomenon is caused by the combined influence of tensile [...] Read more.
Hydrogen sulfide (H2S) is considered a toxic and corrosive gas, commonly found in natural gas, crude oil, and other fossil fuels. This corrosive gas may lead to stress corrosion cracking (SCC). This phenomenon is caused by the combined influence of tensile stress and a corrosive environment. This may lead to the sudden failure of normally ductile metal alloys, especially at an elevated temperature. Desulfurization is the process of removing H2S from these fuels to reduce their harmful environmental and health impacts. Ionic liquids (ILs) have shown great potential for application as liquid absorbents for H2S extraction because of their advantages such as non-volatility, functionality, high carbon solubility and low energy requirements for regeneration. The proposed hydrogen sulfide extraction system consists of a tube, membrane and shell. 1-ethyl-3-methylimidazolium (emim)-based ionic liquids with bis-(trifluoromethyl) sulfonylimide (NTf2) anion has been selected due to its high H2S diffusion coefficient. Functionalized graphene oxide (GO) advanced membranes have been employed in this design. In this research, H2S extraction with ionic liquids has been numerically studied. The COMSOL finite element and multi-physics code has been employed to solve the continuity, turbulent fluid flow (k-ε model), and transient diffusion equations. For small time periods, there is sharp gradient in H2S concentration profile inside the shell section. This is because the diffusion coefficient of H2S in the ionic liquid is very small and the shell section is much thicker than the membrane. It has been determined that H2S is absorbed almost completely by ionic liquids after a time period of 30,000 s. Full article
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12 pages, 5981 KiB  
Article
2D and 3D TEM Characterisation of Benzene and Ethylene Soot
by Salvatore Lagana, Antonino La Rocca, Alasdair Cairns, Michael W. Fay, Barbara Apicella, Anna Ciajolo and Carmela Russo
Fuels 2023, 4(2), 174-185; https://doi.org/10.3390/fuels4020011 - 28 Apr 2023
Viewed by 2330
Abstract
Flame-generated soot particles from two different fuels, benzene (B) and ethylene (E), at different ageing conditions, were analysed to assess their morphological and structural features. Samples were collected at 6, 10 and 14 mm from the nozzle location. Traditional 2D transmission electron microscopy [...] Read more.
Flame-generated soot particles from two different fuels, benzene (B) and ethylene (E), at different ageing conditions, were analysed to assess their morphological and structural features. Samples were collected at 6, 10 and 14 mm from the nozzle location. Traditional 2D transmission electron microscopy (TEM) and a novel 3D TEM were used to investigate morphology variations. High-resolution TEM (HRTEM) was used to capture structural characteristics. Samples were then placed on lacey carbon microgrids. A field emission gun TEM was used to capture images of the agglomerates. Tilt series of ±60 degrees were acquired at 1-degree steps to perform the 3D reconstruction. IMOD software and backwards projection were used to reconstruct the tomogram from the tilt series. The 2D analysis revealed that soot particles’ agglomerations for both fuels change from a bundle to a chain-like structure as they “age”, i.e., extracted at a higher “flame height”. In B, the primary particle diameter increases as they get “older,” whereas in E, the opposite happens, and overall, E particles are bigger than B ones. The nanostructure presents ordered regions with parallel-stacked layers of carbon lamellae. This is more evident in the aged soot samples, with the difference that in E a thick amorphous layer is present at the edge of the particles, which is not observable for B. A nanostructure analysis suggests a trend of increasing fringes length as the soot ages, going from 1.04 nm of B6 to 1.22 nm of B10 to 1.05 nm of B14 and from 1.139 nm of E6 to 1.20 nm of E14 (±0.02 nm). The tortuosity does not vary greatly across all the samples, ranging between 1.132 and 1.149 (±0.004). Separation is also quite similar everywhere, with 0.404 nm of B6, 0.392 nm of B10, 0.399 nm of B14, 0.397 nm of E6 and 0.396 nm of E14 (±0.002 nm). Ring structures and particle overlaps, two examples of geometrical characteristics concealed in 2D, can be seen in the 3D reconstructions. Furthermore, the comparison between 3D and 2D volume and surface area raises questions about the reliability of those parameters as derived from 2D measurements. This study advances knowledge of how soot structure can be affected by the fuel type and emphasises the significance of how soot is investigated. Full article
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16 pages, 3507 KiB  
Article
Investigating the Effect of Volatiles on Sub-23 nm Particle Number Measurements for a Downsized GDI Engine with a Catalytic Stripper and Digital Filtering
by Sebastian A. Pfau, Ephraim Haffner-Staton, Antonino La Rocca and Alasdair Cairns
Fuels 2022, 3(4), 682-697; https://doi.org/10.3390/fuels3040041 - 21 Nov 2022
Viewed by 2272
Abstract
Recent efforts of both researchers and regulators regarding particulate emissions have focused on the contribution and presence of sub-23 nm particulates. Despite being previously excluded from emissions legislation with the particle measurement programme (PMP), the latest regulatory proposals suggest lowering the cut-off sizes [...] Read more.
Recent efforts of both researchers and regulators regarding particulate emissions have focused on the contribution and presence of sub-23 nm particulates. Despite being previously excluded from emissions legislation with the particle measurement programme (PMP), the latest regulatory proposals suggest lowering the cut-off sizes for counting efficiencies and the use of catalytic strippers to include solid particles in this size range. This work investigated particulate emissions of a 1.0 L gasoline direct injection (GDI) engine using a differential mobility spectrometer (DMS) in combination with a catalytic stripper. Direct comparison of measurements taken with and without the catalytic stripper reveals that the catalytic stripper noticeably reduced variability in sub-23 nm particle concentration measurements. A significant portion of particles in this size regime remained (58–92%), suggesting a non-volatile nature for these particles. Digital filtering functions for imposing defined counting efficiencies were assessed with datasets acquired with the catalytic stripper; i.e., particle size distributions (PSDs) with removed volatiles. An updated filtering function for counting efficiency thresholds of d65 = 10 nm and d90 = 15 nm showed an increase in particulate numbers between 1.5% and up to 11.2%, compared to the closest previous digital filtering function. However, this increase is highly dependent on the underlying PSD. For a matrix of operating conditions (1250 to 2250 rpm and fast-idle to 40 Nm brake torque), the highest emissions occurred at fast-idle 1250 rpm with 1.93 × 108 #/cm3 using the updated filtering function and catalytic stripper. This setup showed an increase in particulate number of +27% to +390% over the test matrix when compared to DMS measurements without the catalytic stripper and applied counting efficiency thresholds of d50 = 23 nm and d90 = 41. Full article
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10 pages, 1533 KiB  
Article
Characterization Techniques Coupled with Mathematical Tools for Deepening Asphaltene Structure
by Barbara Apicella, Anna Ciajolo, Andrea Carpentieri, Ciprian Popa and Carmela Russo
Fuels 2022, 3(1), 75-84; https://doi.org/10.3390/fuels3010005 - 27 Jan 2022
Cited by 3 | Viewed by 2552
Abstract
Asphaltenes are the heavy fraction of fossil fuels, whose characterization remains a very difficult and challenging issue due to the still-persisting uncertainties about their structure and/or composition and molecular weight. Asphaltene components are highly condensed aromatic molecules having some heteroatoms and aliphatic functionalities. [...] Read more.
Asphaltenes are the heavy fraction of fossil fuels, whose characterization remains a very difficult and challenging issue due to the still-persisting uncertainties about their structure and/or composition and molecular weight. Asphaltene components are highly condensed aromatic molecules having some heteroatoms and aliphatic functionalities. Their molecular weights distribution spans in a wide range, from hundreds to millions of mass units, depending on the diagnostic used, which is mainly due to the occurrence of self-aggregation. In the present work, mass spectrometry along with size exclusion chromatography and X-ray diffraction analysis have been applied to asphaltenes for giving some further insights into their molecular weight distribution and structural characteristics. Relatively small polycyclic aromatic hydrocarbons (PAHs) with a significant degree of aliphaticity were individuated by applying fast Fourier transform (FFT) and double bond equivalent (DBE) number analysis to the mass spectra. X-ray diffraction (XRD) confirmed some aliphaticity, showing peaks specific of aliphatic functionalities. Size exclusion chromatography indicated higher molecular weight, probably due to the aliphatic substituents. Mass spectrometry at high laser power enabled observing a downward shift of molecular masses corresponding to the loss of about 10 carbon atoms, suggesting the occurrence of aryl-linked core structures assumed to feature asphaltenes along with island and archipelago structures. Full article
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10 pages, 2852 KiB  
Article
Towards Biomass Gasification Enhanced by Structured Iron-Based Catalysts
by Giovanna Ruoppolo and Gianluca Landi
Fuels 2021, 2(4), 546-555; https://doi.org/10.3390/fuels2040032 - 6 Dec 2021
Viewed by 2603
Abstract
The main drawback for the development of biomass gasification technology is tar conversion. Among the various methods for tar abatement, the use of catalysts has been proposed in the literature. Most of the works reported in the literature on catalytic systems for biomass [...] Read more.
The main drawback for the development of biomass gasification technology is tar conversion. Among the various methods for tar abatement, the use of catalysts has been proposed in the literature. Most of the works reported in the literature on catalytic systems for biomass tar conversion refers to catalysts in the form of powder; however, deactivation occurs by fast clogging with particulates deriving from biomass gasification. The integration of catalytic filter element for particle and tar removal directly integrated into the freeboard of the reactor is a new concept recently proposed and patented. In this context, this paper evaluates the possibility to integrate a structured iron-based catalytic monolith in the freeboard of a fluidized bed gasifier to enhance biomass gasification. The effectiveness of using a monolith for gas conditioning has been preliminarily verified. The limited effect on the gas production and composition seems to be related to the limited range of operating conditions explored in this work rather than to the low activity of the iron-based catalyst. Further studies to optimize the performance and to assess the possible deactivation of the catalyst due to coke deposition must be carried out. Full article
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11 pages, 720 KiB  
Article
Quantitative and Sensitive Mid-Infrared Frequency Modulation Detection of HCN behind Shock Waves
by Michael Stuhr, Sebastian Hesse and Gernot Friedrichs
Fuels 2021, 2(4), 437-447; https://doi.org/10.3390/fuels2040025 - 29 Oct 2021
Cited by 8 | Viewed by 3098
Abstract
Despite its key role for the study and modeling of nitrogen chemistry and NOx formation in combustion processes, HCN has only rarely been detected under high-temperature conditions. Here, we demonstrate quantitative detection of HCN behind incident and reflected shock waves using a [...] Read more.
Despite its key role for the study and modeling of nitrogen chemistry and NOx formation in combustion processes, HCN has only rarely been detected under high-temperature conditions. Here, we demonstrate quantitative detection of HCN behind incident and reflected shock waves using a novel sensitive single-tone mid-infrared frequency modulation (mid-IR-FM) detection scheme. The temperature-dependent pressure broadening of the P(26) line in the fundamental CH stretch vibration band was investigated in the temperature range 670KT1460K, yielding a pressure broadening coefficient for argon of 2γAr296K=(0.093±0.007)cm1atm1 and a temperature exponent of nAr=0.67±0.07. The sensitivity of the detection scheme was characterized by means of an Allan analysis, showing that HCN detection on the ppm mixing ratio level is possible at typical shock wave conditions. In order to demonstrate the capability of mid-IR-FM spectroscopy for future high-temperature reaction kinetic studies, we also report the first successful measurement of a reactive HCN decay profile induced by its reaction with oxygen atoms. Full article
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10 pages, 2702 KiB  
Article
On the Application of Electron Energy-Loss Spectroscopy for Investigating Nanostructure of Soot from Different Fuels
by Carmela Russo, Miroslawa Pawlyta, Anna Ewa Tomiczek, Anna Ciajolo and Barbara Apicella
Fuels 2021, 2(3), 367-375; https://doi.org/10.3390/fuels2030021 - 16 Sep 2021
Cited by 4 | Viewed by 3725
Abstract
Soot is characterized by a multiscale structural organization; the only diagnostic tool that can give access to it is the transmission electron microscope (TEM). However, as it is a diffraction-based technique, TEM images only conjugate aromatic systems and, thus, it is particularly useful [...] Read more.
Soot is characterized by a multiscale structural organization; the only diagnostic tool that can give access to it is the transmission electron microscope (TEM). However, as it is a diffraction-based technique, TEM images only conjugate aromatic systems and, thus, it is particularly useful to combine it with electron energy-loss spectroscopy (EELS), which is able to provide quantitative information about the relative abundance of sp3 and sp2 hybridized carbon. In this paper, a method for the EELS spectrum analysis of carbonaceous materials, recently developed for electron-irradiated graphite and glassy carbon composition analysis, has been applied for the first time on soot samples, in order to test its performance in soot nanostructure study in combination with TEM and high-resolution TEM (HRTEM). Soot samples analyzed were collected in the soot inception region of premixed flames of different hydrocarbon fuels. EELS, in agreement with TEM and HRTEM, showed a quite disordered and heterogeneous structure for young soot, with a relatively low sp2 content and slight presence of fullerene-like structures, more evident in the case of methane soot hinting to the effect of more saturated aliphatic fuels on soot characteristics at soot inception. Full article
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