Victor Tulus Merlich

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Tulus Merlich

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Victor

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0000-0001-8774-9492

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Publications 1 - 10 of 21

Geminal-atom catalysis for cross-coupling
Hai, Xiao; Zheng, Yang; Yu, Qi; et al. (2023)
Nature
Single-atom catalysts (SACs) have well-defined active sites, making them of potential interest for organic synthesis 1–4. However, the architecture of these mononuclear metal species stabilized on solid supports may not be optimal for catalysing complex molecular transformations owing to restricted spatial environment and electronic quantum states 5,6. Here we report a class of heterogeneous geminal-atom catalysts (GACs), which pair single-atom sites in specific coordination and spatial proximity. Regularly separated nitrogen anchoring groups with delocalized π-bonding nature in a polymeric carbon nitride (PCN) host 7 permit the coordination of Cu geminal sites with a ground-state separation of about 4 Å at high metal density 8. The adaptable coordination of individual Cu sites in GACs enables a cooperative bridge-coupling pathway through dynamic Cu–Cu bonding for diverse C–X (X = C, N, O, S) cross-couplings with a low activation barrier. In situ characterization and quantum-theoretical studies show that such a dynamic process for cross-coupling is triggered by the adsorption of two different reactants at geminal metal sites, rendering homo-coupling unfeasible. These intrinsic advantages of GACs enable the assembly of heterocycles with several coordination sites, sterically congested scaffolds and pharmaceuticals with highly specific and stable activity. Scale-up experiments and translation to continuous flow suggest broad applicability for the manufacturing of fine chemicals.
PULPO: A framework for efficient integration of life cycle inventory models into life cycle product optimization
Lechtenberg, Fabian; Istrate, Robert; Tulus Merlich, Victor; et al. (2024)
Journal of Industrial Ecology
This work presents the PULPO (Python-based user-defined lifecycle product optimization) framework, developed to efficiently integrate life cycle inventory (LCI) models into life cycle product optimization. Life cycle optimization (LCO), which has found interest in both the process systems engineering and life cycle assessment (LCA)communities, leverages LCA data to go beyond simple assessments of a limited number of alternatives and identify the best possible product systems configuration subject to a manifold of choices, constraints, and objectives. However, typically, aggregated inventories are used to build the optimization problems. Contrary to existing frame-works, PULPO integrates whole LCI databases and user inventories as a backbone for the optimization problem, considering economy-wide feedback loops between fore-and background systems that would otherwise be omitted. The open-source implementation combines functions from Brightway2 for the manipulation of inventory data and pyomo for the formulation and solution of the optimization problem. The advantages of this approach are demonstrated in a case study focusing on the design of optimal future global green methanol production systems from captured CO2 and electrolytic H2. It is shown that the approach can be used to assess sector-coupling with multi-functional processes and prospective background databases that would otherwise be impractical to approach from a standalone LCA perspective. The use of PULPO is particularly appealing when evaluating large-scale decisions that have a strong impact on socioeconomic systems, resulting in changes in the technosphere on which the background system is based and which is often assumed constant in standard LCO approaches regardless of the decisions taken.
Absolute environmental sustainability assessment of renewable dimethyl ether fuelled heavy-duty trucks
Charalambous, Margarita Athanasia; Tulus Merlich, Victor; Ryberg, Morten W.; et al. (2023)
Sustainable Energy & Fuels
In recent years, liquid fuels from renewable carbon that can replace fossil ones with minimal infrastructure changes have attracted increasing interest in decarbonising the heavy-duty long-haul sector. Here we focus on dimethyl ether (DME), a promising alternative to diesel due to its high cetane number, oxygen content, and more efficient and cleaner propulsion that results in low particulate matter and sulphur oxide emissions. Going well beyond previous studies that quantified the environmental impact of DME, often in terms of global warming, here we evaluate DME use in heavy-duty trucks in the context of seven planetary boundaries, all essential for maintaining the Earth's stability. Focusing on several scenarios differing in the feedstock origin, we find that routes based on fossil carbon, either in the form of coal, natural gas, or captured CO2 from fossil plants, would increase the greenhouse gas emissions relative to the business-as-usual. Only scenarios based on renewable carbon could reduce the impacts on climate change, while hydrogen from biomass gasification coupled with carbon capture and storage (CCS) and DME from biomass gasification with CCS could enable an environmentally sustainable operation within all the planetary boundaries. Overall, our work opens up new avenues for the environmental assessment of fuels considering the finite capacity of the Earth system to guide research and policy-making more sensibly.
The environmental sustainability of digital content consumption
Istrate, Robert; Tulus Merlich, Victor; Grass, Robert N.; et al. (2024)
Nature Communications
Internet access has reached 60% of the global population, with the average user spending over 40% of their waking life on the Internet, yet the environmental implications remain poorly understood. Here, we assess the environmental impacts of digital content consumption in relation to the Earth’s carrying capacity, finding that currently the global average consumption of web surfing, social media, video and music streaming, and video conferencing could account for approximately 40% of the per capita carbon budget consistent with limiting global warming to 1.5 °C, as well as around 55% of the per capita carrying capacity for mineral and metal resources use and over 10% for five other impact categories. Decarbonising electricity would substantially mitigate the climate impacts linked to Internet consumption, while the use of mineral and metal resources would remain of concern. A synergistic combination of rapid decarbonisation and additional measures aimed at reducing the use of fresh raw materials in electronic devices (e.g., lifetime extension) is paramount to prevent the growing Internet demand from exacerbating the pressure on the finite Earth’s carrying capacity.
Microalgae Biofuel for a Heavy-Duty Transport Sector within Planetary Boundaries
Cabrera-Jiménez, Richard; Tulus Merlich, Victor; Gavaldá, Jordi; et al. (2023)
ACS Sustainable Chemistry & Engineering
In this contribution, we study the extent to which 68 scenarios for microalgae biofuels could help the heavy-duty transport sector operate within planetary boundaries. The proposed scenarios are built considering a range of alternative configurations based on three types of fuel production processes (i.e., transesterification, hydrodeoxygenation, and hydrothermal liquefaction), different carbon sources (such as natural gas power plants and direct air capture), byproduct treatments, and two electricity mixes. Our results reveal that microalgae biofuels could significantly reduce the environmental and human health impacts of the business-as-usual (fossil-based) heavy-duty transport sector. Moreover, relative to standard biofuels that show large land-use requirements, we find that microalgae biofuels also decrease the damage on biosphere integrity substantially. Notably, pathways resorting to hydrodeoxygenation of microalgae oil and direct air capture and carbon storage could reduce the current impact induced globally on climate change by the heavy transport by 77%, while attaining six-fold reductions in biosphere integrity impacts, both relative to conventional biofuels.
Aiming for More Sustainable Cross-Coupling Chemistry by Employing Single-Atom Catalysis on Scale
Poier, Dario; Mitchell, Sharon; Tulus Merlich, Victor; et al. (2023)
Chimia
Scaling up syntheses from mg to kg quantities is a complex endeavor. Besides adapting laboratory protocols to industrial processes and equipment and thorough safety assessments, much attention is paid to the reduction of the process' environmental impact. For processes including transition metal catalyzed steps, e.g., cross-coupling chemistry, this impact strongly depends on the identity of the metal used. As such, a key approach is the replacement of single-use with reusable heterogeneous catalysts. Transition metal single-atom heterogeneous catalysts (SAC), a novel class of catalytic materials, might exhibit all the necessary properties to step up to this task. This article shall discuss current applications of SAC in cross-coupling chemistry from the point of a process chemist and shed light on the NCCR Catalysis contribution to the field. Investigations of the stability-activity-selectivity relationship of SACs in combination with early-stage life-cycle assessments (LCA) of potential processes lay the foundation for large-scale application tailored catalyst synthesis. Ultimately, prevailing challenges are highlighted, which need to be addressed in future research.
Integrating emerging technologies deployed at scale within prospective life cycle assessments
Charalambous, Margarita Athanasia; Sacchi, Romain; Tulus Merlich, Victor; et al. (2024)
Sustainable Production and Consumption
Climate policies will strongly affect future supply chains in ways that can be predicted using integrated assessment models (IAMs). The outcomes of IAMs are now being used to conduct prospective life cycle assessments (pLCA) where the background data reflects expected future changes in the economy. However, the technological representation of emerging technologies is often limited in IAMs, which cover a reduced number of routes, thus offering limited insights into their role in future scenarios. This study addresses this gap by integrating emerging technologies omitted in IAMs into future markets, providing a more robust foundation for pLCAs. Diesel, widely used in transportation, heating, and power systems, has established itself as an integral part of the world's infrastructure. Hence, to illustrate our approach, here we analyze the future environmental impacts of heavy-duty trucks fueled with synthetic Fischer-Tropsch e-diesel, incorporating our technology in the diesel market of the background system, through an integrated LCA approach. The standard non-integrated LCA would analyze these technologies in the foreground, assuming that the background is given. In contrast, our integrated LCA, which is particularly suited for cases where technologies in the foreground are deployed at scale, makes both systems consistent with each other. Our findings reveal mismatches in climate impacts depending on the climate pathway and technology of up to 35 % between the integrated and non-integrated approaches, which increase over time, particularly from 2020 to 2050, and are more pronounced when assessing highly carbon-negative or carbon-positive technologies. Overall, we stress the importance of having consistent foreground and background systems for performing more meaningful and accurate LCAs. Moreover, we provide detailed guidelines on implementing such integrated analysis in current software packages, aiming to enhance the reliability of pLCAs for emerging technologies.
Planetary Boundaries Analysis of Low-Carbon Ammonia Production Routes
D'Angelo, Sebastiano Carlo; Cobo Gutiérrez, Selene; Tulus Merlich, Victor; et al. (2021)
ACS Sustainable Chemistry & Engineering
At present, the synthesis of ammonia through the Haber-Bosch (HB) process accounts for 1.2% of the global carbon emissions, representing roughly one-fourth of the global fossil consumption from the chemical industry, which creates a pressing need for alternative low-carbon synthesis routes. Analyzing seven essential planetary boundaries (PBs) for the safe operation of our planet, we find that the standard HB process is unsustainable as it vastly transgresses the climate change PB. In order to identify more responsible strategies from this integrated perspective, we assess the absolute sustainability level of 34 alternative routes where hydrogen (H-2) is supplied by steam methane reforming with carbon capture and storage, biomass gasification, or water electrolysis powered by various energy sources. We found that some of these scenarios could substantially reduce the global impact of fossil HB, yet alleviating the impact on climate change could critically exacerbate the impacts on other Earth-system processes. Furthermore, we identify that reducing the cost of electrolytic H-2 is the main avenue toward the economic appeal of the most sustainable routes. Our work highlights the need to embrace global impacts beyond climate change in the assessment of decarbonization routes of fossil chemicals. This approach enabled us to identify more suitable alternatives and associated challenges toward environmental and economically attractive ammonia synthesis.
Optimising fuel supply chains within planetary boundaries: A case study of hydrogen for road transport in the UK
Ehrenstein, Michael; Galán Martín, Ángel; Tulus Merlich, Victor; et al. (2020)
Applied Energy
The world-wide sustainability implications of transport technologies remain unclear because their assessment often relies on metrics that are hard to interpret from a global perspective. To contribute to filling this gap, here we apply the concept of planetary boundaries (PBs), i.e., a set of biophysical limits critical for operating the planet safely, to address the optimal design of sustainable fuel supply chains (SCs) focusing on hydrogen for vehicle use. By incorporating PBs into a mixed-integer linear programming model (MILP), we identify SC configurations that satisfy a given transport demand while minimising the PBs transgression level, i.e., while reducing the risk of surpassing the ecological capacity of the Earth. On applying this methodology to the UK, we find that the current fossil-based sector is unsustainable as it transgresses the energy imbalance, CO2 concentration, and ocean acidification PBs heavily, i.e., five to 55-fold depending on the downscale principle. The move to hydrogen would help to reduce current transgression levels substantially, i.e., reductions of 9–86% depending on the case. However, it would be insufficient to operate entirely within all the PBs concurrently. The minimum impact SCs would produce hydrogen via water electrolysis powered by wind and nuclear energy and store it in compressed form followed by distribution via rail, which would require as much as 37 TWh of electricity per year. Our work unfolds new avenues for the incorporation of PBs in the assessment and optimisation of energy systems to arrive at sustainable solutions that are entirely consistent with the carrying capacity of the planet. © 2020 Elsevier Ltd.
Level of decoupling between economic growth and environmental pressure on Earth-system processes
Vázquez, Daniel; Galán Martín, Ángel; Tulus Merlich, Victor; et al. (2023)
Sustainable Production and Consumption
Ensuring economic growth without challenging the Earth's resiliency is crucial to achieving sustainable development. Capitalizing on the planetary boundaries framework as the limits to growing safely, here we present a temporal assessment of the link between economic growth and pressure exerted on the environment using the Exiobase database. By studying the degree of decoupling between absolute sustainability metrics and economic indicators, we find that strong decoupling at a global scale has not occurred in any planetary boundary, with the impact on the planetary boundaries increasing at a slower pace than the global gross domestic product but not decreasing in the studied period (1995 to 2019). Our results also reveal that some countries shifted burdens overseas, thereby exhibiting lower decoupling rates on a production-based basis (vs. consumption-based). Moreover, we found that countries responsible for exerting the highest stress on the planetary boundaries tend to transgress their downscaled safe operating space and present weak decoupling. Considering future economic growth, tailored strategies will be needed to operate within the limits of the Earth, including complementing the gross domestic product with additional indicators to drive human development sustainably.

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