Search Results (475)

Tri-reforming of methane (TRM) has emerged as a promising pathway for low-carbon syngas production by integrating steam reforming, dry reforming, and partial oxidation within a single process. This coupling enables simultaneous CH₄ utilization and CO₂ valorization while enabling internal heat generation and flexible adjustment of the H₂/CO ratio for downstream synthesis. However, TRM performance cannot be adequately evaluated using conversion or energy efficiency alone, because the process involves complex interactions among competing reaction pathways, transport phenomena, catalyst stability, and thermodynamic irreversibility. This review provides a multiscale critical assessment of TRM from both first-law energy and second-law exergy perspectives, linking reaction-network fundamentals to reactor-level behavior and system-level performance. The literature evidence shows that although high temperatures and near-autothermal operation can enhance CH₄ conversion and reduce external heat demand, these conditions may simultaneously intensify deep oxidation, hotspot formation, carbon-forming tendencies, and exergy destruction. While equilibrium analyses help define feasible operating windows, they are insufficient without kinetic modeling and reactor-scale studies that capture spatial non-uniformities and pathway competition. Across reported TRM systems, exergy destruction is consistently concentrated within the reformer, identifying the reacting core as the dominant thermodynamic bottleneck. Accordingly, the key challenge in TRM is not simply to maximize conversion but to preserve chemical work potential while maintaining syngas quality and operational stability. Viewed from this perspective, TRM is better understood as an irreversibility-aware multiscale design problem in which optimal performance depends on the integrated optimization of catalyst functionality, reactor architecture, heat management, and system-level operation. Full article

The selective conversion of syngas (CO + H₂) to higher alcohols (C₂₊OH) via Fischer–Tropsch synthesis (FTS) is a strategically important but challenging process, requiring catalysts that can simultaneously sustain C–C chain growth and preserve C–O bonds in reactive intermediates. Over the past decade (2015–2025), perovskite-type complex oxides with the formula ABO₃ have emerged as powerful precatalysts for this application, with LaCoO₃ attracting particular attention due to its structural flexibility, controllable reducibility, and the unique catalytic role of the La₂O₃ phase formed upon reduction. This review systematically covers recent advances in synthesis strategies for LaCoO₃ and substituted perovskites, including sol–gel, co-precipitation, mechanochemical, and template-assisted (KIT-6, SBA-15) methods; effects of A-site (Sr) and B-site (Cu, Ga, Ni, Mn) substitution on reducibility, active phase dispersion, and product selectivity; alkali promotion and its interaction with the perovskite-derived active phase; mechanistic understanding of the alcohol-forming pathway, including the Co⁰/Co³⁺ bifunctional site concept, CO insertion mechanism, and the role of La₂O₃ in suppressing the Boudouard reaction; and catalyst stability and deactivation pathways under FTS conditions. Original data from LaCoO₃ catalysts prepared by co-precipitation with ethylene glycol (LCO-1: S_KOH = 90%, Y_KOH = 57 mg·g⁻¹·h⁻¹) and via citrate/KIT-6 template synthesis (LCO/KIT-6: Y_KOH = 80 mg·g⁻¹·h⁻¹, S_BET = 220 m²/g) at 240 °C and 2 MPa serve as the primary experimental reference throughout. Key challenges, including the surface area–selectivity trade-off, long-term stability under industrial conditions, and opportunities in CO₂ hydrogenation, are critically discussed. Full article

Dry reforming of methane (DRM) is a key reaction for syngas production and greenhouse gas utilisation, involving multiple interacting operating variables. In this work, an interpretable machine learning approach based on CatBoost regression coupled with SHapley Additive exPlanations (SHAP) is applied to a previously published DRM dataset to analyse the influence of reaction temperature, CH₄/CO₂ feed ratio, and Ni loading on CH₄ and CO₂ conversions and H₂ and CO yields. The objective of this study is methodological rather than experimental, focusing on the use of interpretable machine learning to extract variable importance hierarchies and conditional interaction effects from data-limited DRM studies. The analysis confirms that reaction temperature is the dominant controlling parameter, while feed ratio and Ni loading exhibit secondary, regime-dependent influences. No new catalytic mechanisms or experimental findings are proposed. The results illustrate how CatBoost–SHAP analysis can complement experimental DRM research by providing transparent, quantitative interpretation of published datasets under realistic data constraints. These findings are consistent with established DRM thermodynamic and kinetic behaviour, where temperature governs endothermic reforming reactions, while feed composition and metal loading influence carbon formation pathways and catalytic activity. Full article

The interest in more sustainable energy sources has necessitated research in hydrogen production from various reliable pathways. This study investigates the potential of hydrogen production by ethanol-assisted CO₂ reforming over Al-MCM-41-supported Ni catalysts considering the effect on the catalytic performance and stability. The Ni/Al-MCM-41 catalysts were synthesized via wet impregnation method and characterized using different instruments and techniques. Evidence of the formation of well-crystallized Ni nanoparticles dispersed on the Al-MCM-41 support was confirmed by X-ray diffraction analysis and field emission scanning electron microscopy. The amount of Ni loading, which varied from 5 to 15%, was confirmed using energy-dispersive analysis, while the mesoporous nature of the Ni/Al-MCM-41 was ascertained using N₂ physisorption analysis. The performance of the Ni/Al-MCM-41 catalyst as a function of the ethanol conversion, CO₂ conversion, hydrogen and CO yield is strongly corrected with Ni loading and reaction temperature. The ethanol conversion and hydrogen yield increase with the increase in reaction temperature. At a reaction temperature of 550 °C the lowest ethanol conversion and hydrogen yield of 32.3% and 33.7% were obtained over the 5 wt% Ni/Al-MCM-41 catalyst, while the highest ethanol conversion of 87.4% and hydrogen yield of 75.5% were obtained over the 15% Ni/Al-MCM-41 at 700 °C. The 15 wt% catalyst achieves the most balanced syngas profile at 700 °C, where the H₂ and CO yields are optimized through the synergistic consumption of both ethanol and CO₂. It can be inferred that the reaction follows a bifunctional pathway whereby the Ni active sites are responsible for the ethanol dissociation while the CO₂ adsorption and activation are enhanced by the Al-MCM-41 support. Full article

Dry reforming of methane (DRM) converts the greenhouse gases methane (CH₄) and carbon dioxide (CO₂) into syngas (hydrogen (H₂) and carbon monoxide (CO)). Despite its numerous advantages, DRM has not yet been industrialized due to catalyst deactivation and competing side reactions. While Ni-based catalysts have been widely used, they are prone to increased carbon deposition and sintering, and although bimetallic systems and oxygen-based supports have shown promise, their effects on carbon deposition are yet to be fully understood. In this study, carbon nanotube (CNT)-supported Pt-Ni catalysts incorporating mixed oxides of CeZrO₂ and CeZrLaO₂ were investigated to evaluate the impact of support composition and metal–support interactions in DRM. The catalysts were synthesized and subsequently tested in DRM. Catalysts supported on CNTs displayed higher CH₄ and CO₂ conversions compared to conventional ceria–zirconia, highlighting the beneficial role of the carbon nanotube support in improving dispersion and accessibility of the metal active sites. Addition of Pt was found to promote reverse water–gas shift (RWGS) reaction, whereas the addition of La was found to decrease catalytic activity. Despite the formation of a Ni-Pt alloy, the obtained catalysts favored RWGS over DRM. These findings illustrate key limitations and design considerations for optimization of CNT-supported bimetallic catalysts in DRM. Full article

The rapid accumulation of plastic and biomass waste has emerged as a major environmental and resource management challenge, driven by increasing global consumption, low recycling efficiency, and the long-term persistence of waste in natural ecosystems. Conventional valorization routes such as pyrolysis, gasification, reforming, and fermentation provide promising pathways for converting waste into fuels and chemicals, yet their industrial deployment remains constrained by thermodynamic limitations, tar formation, catalyst deactivation, high energy demand, and complex downstream separation requirements. Despite increasing research activity, a comprehensive review that systematically addresses membrane reactor (MR) mechanisms, configurations, and their specific applications in the valorization of both plastic and biomass waste remains lacking in the current literature. In recent years, MR technology has attracted increasing attention as a platform for process intensification, integrating reaction and selective separation within a single unit. By enabling in situ product removal, MRs shift reaction equilibria toward higher conversion, selectivity improvement, and a reduction in separation severity and overall energy consumption. This critical review provides a unified and systematic assessment of MR technologies for the valorization of plastic and biomass waste. Reactor configurations, membrane materials, transport mechanisms, and catalytic systems are comprehensively examined, with particular emphasis on hydrogen-selective, oxygen-permeable, and water-selective membranes and their roles in reforming, tar mitigation, and syngas upgrading. The techno-economic and environmental implications of MR integration are critically discussed, together with current technology readiness levels (TRLs) and scale-up challenges. Overall, this review highlights MRs as a versatile and enabling platform for next-generation waste-to-value technologies and outlines their potential role in supporting the transition toward circular, low-carbon fuel and chemical production. Full article

The growing global energy demand and the urgent need to decarbonize the energy sector are driving the search for renewable and low-impact energy sources. Within this context, the conversion of biomass into hydrogen represents a viable pathway to sustainable energy, enabling both carbon mitigation and circular use of agricultural residues. This research focuses on the simulation of an integrated system that converts viticulture residues, vine prunings and grape stalks into biogenic hydrogen through a combination of pretreatment, gasification, and upgrading stages. The analysis of four different supply scenarios shows that the integration of prunings and stalks ensures the highest hydrogen yield (6.61 × 10⁵ Nm³/year of H₂) and the highest energy self-sufficiency, with 25% of produced syngas used to partially cover internal energy demand. Gasification enables the process to be carbon-negative, saving 1.18 kgCO₂eq for Nm³ of H₂ produced, and economically competitive, with a break-even price of 3.81 €/kg and a return on investment of ten years. The study aligns with the decarbonization goals of the European energy transition, promoting local and circular valorization of agro-industrial waste. Full article

Producing single-cell protein (SCP) from syngas-derived ethanol and acetate offers a sustainable solution to global protein shortages, yet microbial utilization mechanisms for these mixtures remain underexplored. This study establishes a systematic bioconversion strategy using Cyberlindnera jadinii TU389. To mitigate acetaldehyde accumulation during ethanol metabolism, we engineered the strain TU546 to overexpress acylating acetaldehyde dehydrogenase (ADA6). TU546 achieved a maximum biomass of 46.7 g/L and a protein yield of 21.69 g/L, representing enhancements of 28.16% and 23.02% over the wild-type, respectively. Transcriptomic analysis revealed extensive metabolic reprogramming. In the C2 assimilation pathway, upregulated aldehyde dehydrogenase and acetyl-CoA Synthetase 1 accelerated acetate conversion to acetyl-CoA, while downregulated pyruvate decarboxylase and alcohol dehydrogenase minimized carbon flux loss. The upregulation of tricarboxylic acid cycle enzymes, the glyoxylate shunt, and acyl-coA oxidase improved carbon skeleton retention. Moreover, the upregulation of transaminases and N-acetylglutamate synthase, synergized with intensified cell proliferation signaling, redirected amino acid metabolism toward a synthesis-enhanced and degradation-controlled paradigm. This synergistic regulatory network drives the high-efficiency bioconversion of ethanol and acetate into SCP, establishing a molecular mechanistic foundation for the valorization of syngas-derived C2 substrates in biological macromolecule production. Full article

Biomass pyrolysis has emerged as a flexible platform for converting low-value residues into higher-value energy carriers (bio-oil, biochar and gas) and carbon-rich materials, with realistic potential for negative emissions when biochar is deployed in long-lived sinks. Over the last decade, three developments have driven the field forward: first, a finer mechanistic understanding of devolatilization and secondary reactions; second, major improvements in analytical techniques for characterising feedstocks and products; and third, more rigorous techno-economic and life-cycle assessments that place pyrolysis in a broader energy-system context. Recent experimental work on forestry and agro-industrial residues has clarified how biomass composition, ash chemistry and operating conditions jointly govern product yields, energy content and stability. Parallel advances in GC×GC–MS, high-resolution mass spectrometry, NMR and thermogravimetric methods have shifted the discussion from bulk “bio-oil” and “char” to families of molecules and well-defined structural domains, which can be deliberately targeted by reactor and catalyst design. Data-driven models, ranging from support vector machines applied to TGA curves to ANFIS and random forests for yield prediction, are now accurate enough to support process screening and multi-objective optimisation. At the system level, commercial fast pyrolysis biorefineries report overall useful energy efficiencies on the order of 80–86%, while slow pyrolysis configurations centred on biochar can be economically viable when carbon storage and co-products are appropriately valued. Thermodynamic analyses confirm that indirect gasification via fast-pyrolysis oil sacrifices some energy and exergy efficiency relative to direct solid-biomass gasification but may offer logistical and integration advantages. This review synthesises recent work on (i) feedstock and process characterisation; (ii) state-of-the-art analytical methods for bio-oil, biochar and gas; (iii) modelling and machine-learning tools; and (iv) energy-system deployment of pyrolysis products. Throughout, the emphasis is on how characterisation and modelling inform concrete design choices and on the trade-offs that arise when pyrolysis is considered as part of a wider decarbonisation portfolio. By integrating laboratory-scale characterisation with system-level modelling, this review aligns biomass pyrolysis with several United Nations Sustainable Development Goals (SDGs). The optimisation of thermochemical conversion pathways for forestry and agro-industrial residues directly supports SDG 7 (Affordable and Clean Energy) by enhancing the efficiency of bio-oil and syngas production. Furthermore, the deployment of biochar as a stable carbon sink for negative emissions and soil amendment addresses SDG 13 (Climate Action) and SDG 15 (Life on Land). By converting low-value waste streams into high-value energy carriers and chemicals within a circular bioeconomy framework, the research further contributes to SDG 12 (Responsible Consumption and Production) and SDG 9 (Industry, Innovation and Infrastructure). Full article

This study presents a fully integrated process for the flexible conversion of biogenic waste into synthetic natural gas (bio-SNG) and electricity centred on a 100 kWth dual concentric bubbling fluidised bed steam gasifier. The raw syngas is processed in a high-temperature gas cleaning section, and the resulting clean, H₂-rich syngas is directed to three alternative downstream configurations: (i) conventional methanation, (ii) enhanced methanation with external H₂ supplied by a reversible solid oxide cell (rSOC), and (iii) electricity generation via the same rSOC operating in fuel cell mode. The overall process is modelled in Aspen Plus, in which the gasification section is constrained by experimentally derived syngas data, while downstream units are described through thermodynamic and kinetics-based models. Methanation is simulated using a plug-flow reactor model based on validated kinetic expressions, while the rSOC operating in electrolysis and fuel cell mode is modelled using performance parameters of commercial stacks. A plant-wide heat integration strategy based on composite curve analysis is implemented to maximise internal heat recovery and minimise external utilities. The enhanced methanation configuration enables the production of bio-SNG with high methane content (up to 93.3 vol.% dry, N₂-free), with a yield 0.72 kg/kg_Biomass and a fuel efficiency of 70.1%. In electricity production mode, the system reaches an electrical efficiency of 43.1% with complete elimination of auxiliary fuel through thermal integration. These results demonstrate the capability of a single integrated plant to flexibly switch between fuel synthesis and power generation, enhancing adaptability to fluctuating electricity and methane market conditions while maintaining high efficiency. Full article

CuCo-based catalysts are promising candidates for higher alcohol synthesis from syngas, yet their performance is often limited by poor metal dispersion and insufficient Cu-Co synergy. In this work, a series of ordered mesoporous CuCoAl catalysts with varying Cu/Co atomic ratios were synthesized via the evaporation-induced self-assembly (EISA) method. The structural, electronic, and catalytic properties were systematically investigated using N₂ physisorption, XRD, TEM, H₂-TPR, CO-TPD, XPS, and fixed-bed reactor evaluation. The results show that all CuCoAl catalysts prepared by the EISA method possess well-ordered mesoporous structures with high surface areas (up to 235 m²/g) and narrow pore size distributions. The interaction between Cu and Co stabilizes the mesoporous framework, inhibits Cu particle growth, and induces electron transfer from Cu to Co as evidenced by XPS. Among the catalysts tested, Cu₁Co₁Al (Cu/Co = 1:1) exhibits the highest strong CO adsorption capacity (1.54 mmol/g) and surface hydroxyl content (63.29%), achieving a CO conversion of 32.9% with a C₂⁺ alcohol space–time yield of 20.5 mg·gcat⁻¹·h⁻¹. These findings establish clear structure–performance relationships for ordered mesoporous CuCoAl catalysts and provide fundamental guidance for the rational design of efficient catalysts for higher alcohol synthesis. Full article

Waste tyres, with their high carbon content and heating value that is greater than that of coal and biomass, present a potential feedstock for energy recovery. Similarly, automotive paint sludge (APS) is a hazardous waste rich in volatile and inorganics compounds, making it difficult to dispose of safely, but it also has potential for thermochemical conversion. Gasification is a thermochemical process which can turn such wastes into syngas, a mixture mainly composed of carbon monoxide and hydrogen that can be utilized to generate power and produce liquid fuels. To deal with challenges of single feedstock gasification, co-gasification combines two or more feedstocks, taking advantage of synergistic interactions to enhance syngas yield and overall efficiency. In this work, Aspen Plus simulation software is used to develop a model for the co-gasification of waste tyres and automotive paint sludge. Sensitivity analysis was performed with the aim of investigating and optimizing the overall process conditions of waste tyre and APS co-gasification. This study investigated the effect of air (ER) and water feed (SFR) and blend ratios on the adiabatic reaction temperature, product gas composition and heat value of the product syngas. Optimal operating ranges were identified as ER = 0.35–0.40 and SFR = 1.0–1.2 for tyre gasification, ER ≈ 0.50–0.55 for APS-only gasification, and ER = 0.40–0.48 with SFR = 0.8–1.0 for co-gasification blends. Adiabatic temperatures under recommended conditions were typically 700–800 °C. The LHV of syngas decreased with increasing ER, SFR, and APS fraction, falling from ~13 MJ/kg for tyre gasification to below 10 MJ/kg for APS-rich cases due to oxidation and dilution by CO₂ and ash. No positive synergistic effect in syngas quality was observed under thermodynamic equilibrium conditions. APS primarily acted as an ash-rich, low-carbon diluent, reducing CO concentration, heating value and adiabatic temperature. However, potential catalytic interactions from APS mineral matter, which are not represented in the equilibrium model, may produce synergistic effects in practical gasifiers. Full article

The lack of centralized waste management infrastructure in certain regions makes plastic waste an escalating environmental and economic problem. This research investigates how modular portable pyrolysis systems function as sustainable decentralized solutions. A standard shipping container houses a custom-designed pyrolysis unit which demonstrates flexibility and adaptability. The system contains a batch rotary kiln reactor with a processing capacity of 750 kg per batch which is fed with urban plastic waste, to produce pyrolytic oil, syngas and char. The produced pyrolytic oil exhibits an energy content comparable to that of conventional diesel fuel. Additionally, the integration of biomass briquettes and recycled pyrolytic gas can reduce to a big extent the external energy requirements, improving the system’s overall energy autonomy. Therefore, the system becomes economically reliable due to its low operational expenses and the short cycle of approximately 7-h operation. The unit’s mobility enables on-site treatment operations which reduces both transportation emissions and expenses. The analysis includes technical design elements together with performance metrics for different plastics. This conceptual study demonstrates the feasibility of containerized pyrolysis as a practical method to enhance plastic waste chemical recycling rates while presenting a scalable framework for industrial symbiosis and local waste-to-energy conversion. Full article

Power-to-X technologies play a crucial role in accelerating the energy and material transition. A key opportunity lies in integrating these systems with existing bio-based infrastructures such as anaerobic digesters, providing a reliable source of biogenic carbon. Developing effective Power-to-Methanol (PtM) pathways requires a comprehensive understanding of process behavior through detailed simulation, including technical performance, economic feasibility, and environmental consequences. Despite growing interest, substantial variation remains in published levelized methanol costs, and many assessments insufficiently account for the full environmental footprint of production routes. This study evaluates the potential of PtM deployment in the Netherlands by comparing two pathways that utilize biogenic carbon sources: (i) hydrogenation of captured CO₂ using green hydrogen and (ii) dry methane reforming (DMR) of biogas, followed by catalytic syngas conversion to methanol. Results indicate that operational expenses—mainly driven by renewable electricity consumption—far outweigh capital investment. Both routes yield an LCoMeOH of approximately €2630 per tonne, about five times the cost of fossil-based methanol. Life cycle analysis shows that DMR performs more favorably overall, although elevated freshwater ecotoxicity and eutrophication result from digestate application as fertilizer. Continued improvements in renewable energy integration and nutrient recovery technologies are essential for enhancing future economic and environmental performance. Full article

Driven by the growing global energy demand and the pursuit of carbon utilization goals, dry reforming of methane (DRM) has attracted considerable attention for its ability to convert CO₂ and CH₄ into syngas. Biogas, an eco-friendly product of processes such as anaerobic digestion, is primarily composed of CO₂ and CH₄ and ideally meets the feedstock requirements for DRM. In practice, biogas is generated via anaerobic digestion of livestock manure and other organic waste, providing a stable and sustainable source for the DRM reaction and thus enabling waste valorization. Supported Ni⁰ catalysts have become a research focus in this field due to their high catalytic activity and moderate cost. Conventional particulate Ni⁰ catalysts, however, are prone to carbon coking in fixed-bed applications and are difficult to effectively recover and regenerate after the reaction; thus, they are often being discarded, leading to resource waste and environmental burden. To address these issues, this study has designed a novel metal-sintered fleece catalyst support and developed a corresponding reactor. The effects of the catalyst preparation method, activation conditions, and the support structure on DRM performance have been systematically investigated. The spent Ni-based catalyst could be regenerated via calcination to restore catalytic activity and enable multiple cycles of use, significantly extending the catalyst’s lifespan and offering both economic and environmental benefits. Experimental results have demonstrated that the reactor achieved a conversion rate exceeding 80% with near-complete product selectivity. Full article