Dry reforming of methane (DRM) is a promising route for syngas production, especially over nanostructured catalysts. This study reports the synthesis of Ni-Co-Mg-Al-La mixed oxides derived from layered double hydroxides (LDHs) by two methods, conventional co-precipitation and a modified approach involving ultrasonic irradiation (US). The different compositions were characterized by XRD, TG/DTA, N2 adsorption-desorption, and SEM-EDX techniques. XRD and DTA results confirm that ultrasonic irradiation promotes the incorporation of lanthanum ions into the lamellar structure. Moreover, the specific surface areas of samples increase by 25% in the US. Due to the enhancement of physicochemical properties, catalysts prepared using ultrasound exhibited improved catalytic activity, with a 5.5% increase in CO2 conversion and a 4.7% increase in CH4 conversion. The characterization of spent catalysts (XRD, TG/DTA, SEM) revealed minimal carbon formation in the catalysts prepared with ultrasonic irradiation, demonstrating the promoting effect of sonication on the stability of catalysts against carbon deposition.

The toxicity of real biogas on human lung cells exposed at the air-liquid interface (ALI) was studied for the first time. Real biogases were sampled on site at two biomethanation centers, one in France and the other in Lebanon. Biogas was produced from the organic component of household municipal waste (i.e., food/kitchen waste and green waste). The chemical analysis was performed by Gas Chromatography (GC) or by online analyzers, in situ or further after collection of the samples in Tedlar bags or adsorption on Tenax tubes. The real biogases were composed of CH4 and CO2, NH3, H2S, and of some Volatile Organic Compounds, such as BTEX and terpenes. The main biogas components from the two selected biogas plants were closed due to the use of the same Valorga® process, whereas the concentrations of the secondary compounds depended on the origin and nature of waste and on the use of a biogas post-treatment. Green waste produced higher concentrations of terpenes. Moreover, the treatment by desulfurization and by activated charcoal decreased its content in sulfur compounds and BTEX, respectively. Then, the toxicity of the two biogases was investigated by RT-qPCR in human lung cell cultures (BEAS-2B) exposed using the ALI Vitrocell® exposure device. No cytotoxicity was detected in the exposed cells. A dose- and time-dependent induction of inflammation markers was observed at the gene level in relation to oxidative stress in BEAS-2B cells exposed to both biogases. These inductions were mainly higher after exposure to the biogas containing more secondary compounds, such as BTEX. In conclusion, this in vitro mechanistic study confirmed the importance of the post-treatment of the biogas to lower the concentration of secondary compounds. Indeed, elimination of some biogas impurities is essential to avoid high toxicity, for an ideal use of biogas for waste management and renewable energy production.

Carbon neutral energies and fine chemicals are urgently needed in the context of the accelerating global warming and associated extreme weather events. Here we review the conversion of biomass into fuels and chemical compounds with focus on biomass properties, mechanisms of biomass thermal decomposition, bio-oil composition and generation, reactor types, pyrolytic classifications, pyrolysis of pure biomass components, and pyrolysis of wood. The main biomass components, namely cellulose, hemicellulose and lignin, are determined by the Van Soest protocol. Biomass decomposition can be explained by the one-step global mechanism, independent competitive or parallel reactions, the multi-component mechanism, the Broido-Shafizadeh scheme, the secondary tar cracking model and the Ranzi scheme. Pyrolysis can be classified into slow, intermediate, fast, and flash pyrolysis. Reactors comprise fixed bed-, fluidized bed- and multistage reactors.

The efficient degradation of persistent organic pollutants such as lindane remains a major challenge for advanced oxidation processes (AOPs), particularly in heterogeneous Fenton systems where catalytic performance is often limited by nanoparticle aggregation, poor mass transfer, and iron leaching. In this work, we developed iron-based catalysts by embedding Fe2O3 nanoparticles within the intra-wall pores (IWPs) of SBA-15 mesoporous silica using a melt infiltration (MI) strategy applying time-controlled diffusion step. Physicochemical characterization (N-2 physisorption, XRD, HR-TEM, DR UV-Vis, synchrotron PDF analyses) revealed that prolonged infiltration enables the selective confinement of ultrafine hematite nanoparticles (<3 nm) exclusively in the IWPs, while preserving the ordered mesostructure and high surface area of the initial support. Catalytic tests in the Fenton-like oxidation of lindane demonstrated that confinement markedly enhances activity, with degradation efficiency rising from 54 % for external aggregates to 91 % for confined nanoparticles after 240 min at pH 3 and 50 degrees C. Despite higher dispersion promoting some iron release, leaching remained below 2 ppm, significantly lower than values reported for comparable systems. Control experiments confirmed that heterogeneous H2O2 activation at the solid-liquid interface dominates over homogeneous pathways, with confined nanoparticles ensuring efficient radical utilization. These findings establish spatial confinement within SBA-15 as a powerful design principle for stabilizing nanoscale iron oxide while simultaneously improving catalytic efficiency, offering a promising route to robust, next-generation heterogeneous Fenton catalysts for the removal of recalcitrant pollutants.

Dry reforming of methane (DRM) is one of the routes proposed to valorize the CO2 into high value molecules, such as syngas (H-2 + CO) by its reaction with methane. Due to thermodynamic limitation this reaction takes place at high temperatures, above 650 degrees C and in a presence of a catalyst. Ni and Co based catalysts are used in DRM, as Ni is showing good activities and Co is improving the selectivity. As the distribution of these two active sites is the key in achieving high conversions and good stability towards deactivation. In this work, bimetallic nanoparticles with various ratios (total loading of 20 wt%) were supported SBA-15 via phyllosilicate precursors. The Ni-Co bimetallic nanoparticles are obtained by activation in hydrogen. Ni-Co based materials were completely characterized in calcined and reduced phase by XRD, N2-physisorption, TPR, TEM, XPS). Only Ni and/or Co phyllosilicates are obtained indifferent of the ratio used, the deposition precipitation method is resulting in high specific surfaces of 300 m(2)g(-1). After the reduction at 700 degrees C Ni-Co NPs are obtained with sizes between 2 and 7 nm as showed by XRD, TPR with bimetallic distribution of 15Ni-5Co, 10NI-10Co and 5Ni-15Co within single NPs as analyzed by S/TEM-EDX mapping. The catalytic performances over DRM are showing the following tendency 20Ni-0Co = 15Ni-5Co > 10NI-10Co > 5Ni-15Co > 0Ni-20Co, while cobalt reach catalysts are rapidly deactivating after 2 h of reaction. Best results are showed by 15Ni-5Co with conversions of 74.5% and 79% for CH4 and CO2 respectively after 200 h of reaction. The spent catalyst showing only 29 wt% carbon and limited sintering with fewer Ni-Co NPs of similar to 13 nm observed. Such unforeseen stability is associated to the presence NPs with the shell composed majority of Ni active sites and with some Co atoms within the NPs in 15/5 catalyst formulation as shown by XPS and S/TEM-EELS mapping.

The use of biogas to produce hydrogen is currently gaining more attention. One of the drawbacks for the valorization of biogas is the presence of H2S, a hazardous molecule that can cause damage in the metallic internal structures of industries. In this study, the H2S-removal performance of a fungi-based biofilter was investigated. First, an H2S-resistant fungal species was isolated from an industrial digestate and identified as Trichoderma harzianum. The capacity of this microorganism to metabolize H2S in a mineral medium was confirmed. Then, a bioreactor was constructed and put in place to monitor the elimination of gaseous H2S. A mix of cardboard, perlite, woodchips, and wood pellets was used as filling. Microbial development and the outlet gas composition were monitored during a 60-day experimental process during which H2S was completely removed. 97% of the introduced sulphur was detected in the used filling material (fungal species + packing material) by elemental analysis. 24% of the detected sulphur was identified by ion-exchange chromatography as SO42-. Elemental analysis, gas chromatography, and ion-exchange chromatography were used to determine the bioreactor sulphur balance. Metagenomic analysis underlined that H2S elimination was due to the presence of Trichoderma harzianum with a H2S-specific bacterial consortium.

This work reports on the ultrasonic synthesis of layered double hydroxides (LDH), also known as hydrotalcite-type materials. We have studied the influence of ultrasonic irradiation parameters (power, time, temperature) on the physicochemical properties of Ni2Mg4Al1.8La0.2 hydrotalcite-type precursors and related mixed oxides (MO). The low-frequency acoustic cavitation (22 kHz) was applied during the precipitation and aging steps of co-precipitation synthesis and the results were compared to the classical preparation route. The materials were characterized by ATR-FTIR, XRD, N2 adsorption–desorption, SEM-EDX, S/TEM-HAADF, and XPS. Using the combination of acoustic cavitation-assisted precipitation and aging steps, XRD experiments show a higher purity hydrotalcite phase and a better incorporation of lanthanum ions into the LDH structure. As expected, morphological characterization shows a reduction in average crystallite size and an increase in surface area and pore volume, combined with a drastic reduction in synthesis time (45 min at room temperature versus 19 h at 60 °C in conventional synthesis). The insertion of a larger quantity of La is observed by S/TEM-EDSX mapping which also shows a better distribution of lanthanum atoms within the LDH and mixed oxide structures.

The physico-chemical properties of Ni, Ru, Ru-Ni monoclinic ZrO2 catalysts were studied and their catalytic activities in the glycerol steam reforming reaction (GSR) were compared. The cata-lysts were prepared by the wet impregnation method, calcined at 600 degrees C and characterized using XRD, BET, H2-TPR and CO2-TPD techniques. The XRD analyses revealed varying crystallite sizes depending on the active phase nature and composition. The H2-TPR analyses demonstrated that the reducibility of the active metal oxide species and its dispersion were affected by the active phase composition. The CO2-TPD analyses revealed that surface modification following impreg-nation modified the basic properties of the catalysts. The catalytic activity tests (T = 400-700 degrees C, WGFR 9:1, flow rate of 0.025 mL/min) showed that the nickel based catalysts were active while the ruthenium based catalyst was inactive. Combining ruthenium and nickel over zirconia led to smaller Ni particle sizes and a better metal dispersion both of which con-tributed to higher H2 yields and an increased coke resistance. During 24 h on stream, the com-bined Ru-Ni/ZrO2 catalyst maintained a higher total glycerol conversion compared to the Ni/ZrO2 catalyst. Only filamentous coke was identified on the spent catalysts after the stability tests. For a higher water to glycerol feed ratio (WGFR 46:1), encapsulating coke was formed over Ru-Ni/ZrO2 leading to the blockage of active sites and a more rapid catalyst deactivation.

Layered double hydroxides (LDHs) are promising because of some of their several interesting characteristics. LDHs can be synthesized using different preparation methods. The application of ultrasounds (US) in the preparation method leads to reduced synthesis times and better dispersion of particles characterized by small size and narrower particle size distribution. Consequently, the specific surface area is higher in US-prepared samples compared to materials prepared by classical methods. These modified characteristics are responsible for improving the performances of LDHs used as catalyst precursors, adsorbents of dyes and heavy metals, fire suppressants, and other applications.

The sustainable production of biodiesel from waste materials has become of utmost importance in recent years. In this study, cheap CaO catalysts were prepared by calcination of waste scallop seashells (Noble Pectin). The seashells were thermally treated at different temperatures (600-1000 degrees C) and then used in the transesterification of sunflower oil for biodiesel production. The catalysts were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and simultaneous Thermal Gravimetric-Differential Scanning Calorimetry (TG-DSC) tech-niques. The highest Fatty Acid Methyl Esters (FAME) yield (97%) was obtained in the presence of the catalyst calcined at 700 degrees C under the following conditions: a methanol-to-oil molar ratio (MOMR) of 12:1, a catalyst-to -oil ratio (CTOR) of 10 wt%, a stirring rate of 700 rpm, a reaction temperature of 65 degrees C and a reaction time of 4 h. The seashell-derived catalyst was practically stable for at least 4 consecutive runs in the reusability study, maintaining a high FAME yield (>92%). The reaction followed pseudo-first order kinetics, with an activation energy (Ea) of 133.57 kJ/mol and a pre-exponential factor (A) of 4.025 x 1018 min-1. This catalyst additionally exhibited a very high activity in the transesterification of waste cooking oil, with a similar FAME yield of 97%. This shows that this catalyst is promising for potential biodiesel production scale-up schemes and industrial applications.

Hydrogen, an energy carrier identified as the future of power generation and transportation, can be produced by the coupling of the biomass pyrolysis and catalytic reforming of the pyrolysis volatiles. In our study, this process was performed in a two-stage reactor with the pyrolysis of oak wood realized at 700 °C in the first reactor and the catalytic reforming in the second one with the temperature varied from 700 to 800 °C. Three bulk catalysts on the bases of Nickel, Cobalt and Cobalt–Nickel were used. Their effects were investigated on the main products distribution and the gases emitted. It was found that the optimal reforming temperature favoring the syngas formation would be above 750 °C. The reforming with Cobalt–Nickel at 800 °C produced the largest gases yields (43 wt.

Valorization of flax shives biomass is investigated through pyrolysis and in-line catalytic hybrid reforming. We demonstrate that this approach enables the conversion of the biomass into three valuable products namely syngas, biochar, and bio-oil while reducing the emissions of greenhouse gases (CH4 and CO2). Given the increasing attention to syngas and especially hydrogen, pyrolysis and reforming reactor parameters were adjusted to enhance syngas production. Analyzed biochar properties such as contents of carbon (>82

The synthesis method is definitive to tune the physicochemical properties for catalytic materials. In this work, the preparation of Ni-Co-Mg-Al-La mixed oxide derived from layered doubles hydroxides (LDH) phases is reported. The synthesis of Ni-Co-Mg-Al-La (LDH) was studied by co-precipitation and under sonication media. X-ray patterns of the samples prepared by ultrasound showed the incorporation of lanthanum ions within the hydrotalcite based structure, while the specific surface areas of samples prepared by the ultrasound method are showing an increasing with 25 % by comparison with the classic procedure. Due to the better textural and structural properties, the catalysts prepared by ultrasound shows an enhancement of the catalytic activity (CO2 of 90% and CH4 of 87%) toward dry reforming of methane.

The catalytic dry reforming of plastic waste is conducted in two-stage fixed bed reactors. The pyrolysis of polypropylene plastics occurs in the first reactor, and the pyrolyzed gases undergo a reforming reaction with carbon dioxide over a catalyst in the second reactor. The wet impregnation method is used to synthesize Ru-Ni/Al2O3 catalysts, which are then calcined and reduced at 800 degrees C. The results show that as the nickel loading increases, the syngas production increases. Promoting the catalyst with a small quantity of ruthenium significantly improves the plastic conversion into syngas. The dry reforming of poly-propylene over 1Ru15Ni/Al2O3 catalyst resulted in the maximum syngas yield (159 mmolsyngas/gPP) at a 2:1 plastic to catalyst ratio. The catalytic dry reforming of plastics is promising for the production of synthesis gas. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

The catalytic dry reforming of plastic waste is performed in a two-stage fixed bed reactor set-up for synthesis gas production. The pyrolysis of plastics occurs in the first stage, while the dry reforming of the pyrolysates over a synthesized catalyst occurs in the second stage in the presence of carbon dioxide. The plastic used is polypropylene, which is simulating the most produced type of plastic. 25NiAl 2 O 3 and 1Ru25NiAl 2 O 3 are the studied catalysts, synthesized via wet impregnation. The effect of the catalyst’s calcination temperature on its performance is investigated. The results show that a lower calcination temperature revealed improved catalytic performance. The catalyst promoted with ruthenium did not show any deactivation during several consecutive runs. The calcination temperature and the metal promoter play a critical role in determining the stability and activity of the Ni-based catalysts during the dry reforming of polypropylene.