Zeolite-catalysed esterification of biomass-derived acids into high-value esters products: Towards sustainable chemistry

Molecular volume-controlled shape-selective catalysis for synthesis of cinnamate over microporous zeolites

Platform chemicals—such as olefins, ammonia, aromatics, and methanol—serve as fundamental building blocks for the chemical industry. At the same time, they account for 4% of global CO2 emissions, highlighting the need for renewable feedstocks, renewable energy, or other alternative approaches to develop more sustainable production routes toward carbon neutrality. Despite substantial research output, we lack a holistic understanding of where innovation is heading. This gap leaves research planning and policy decisions without a quantitative basis for understanding the directions of innovation. A better understanding of how they differ between platform chemicals is critical for delineating policies and strategic plans toward a net-zero future. Our study addresses this gap by providing unprecedented clarity on global research trends in platform chemicals spanning the last three decades since the establishment of the Green Chemistry principles and other subsequent sustainability approaches for chemical systems, showing the rise, reign, and retreat of topics in this area. For this purpose, we develop a novel approach by integrating topic modelling, generative AI, and expert judgment to analyse >90 000 research articles from Scopus, identifying 62 distinct research topics and tracking their temporal and geographical trends. Our results reveal different innovation patterns across the four platform chemicals. Driven by the concepts of an ammonia or methanol economy, research output has increased for these platform chemicals by a factor of 17 and 6 between 2000 and 2024, respectively. This growth has been led by new strategies like photo- and electrochemical routes, which now account for approximately 65% of ammonia-related research. For olefins and aromatics, innovation patterns show less momentum as research has rather focused on optimising available technologies. Reliance on existing alternative routes (based on renewable methanol) and olefins and aromatics’ molecular complexity could explain this lower momentum. Our quantitative findings can help define research priorities for green chemistry and derive the implications of emerging technological trends on industrial systems regarding future electricity, biomass, and feedstock demand.

Synthesis, characterization and properties of Ni2+-doped ZnAl2O4-based spinel-type solid acid catalysts: SO42−/Zn1-xNixAl2O4

The European Green Deal sends a strong signal for a climate-friendly and CO2-neutral economy. An important aspect to support this is a sustainable and reduced use of resources as well as efficient and green conversion technologies for renewable value-added products. For this reason, electrosynthetic approaches become increasingly important, as electrochemistry fulfils several criteria of green chemistry and offers the possibility to directly use current from renewable energy sources [3]. However, electrolysis and electrosynthesis currently often require the use of platinum group metals (PGM) and need separators, which are mostly based on perfluorinated and polyfluorinated alkyl substances (PFSA). Classical water electrolysis for production of green hydrogen also requires high overvoltage’s, which is due to the oxygen evolution reaction (OER). This is where coupling systems come in, in which the sluggish OER is replaced by a thermodynamically more efficient reaction, such as the electrooxidation of organic substances (EOO). An example of this is the electrooxidation of biobased 5-HMF or various sugars (xylose, glucose) to platform chemicals. When coupled with the hydrogen evolution reaction (HER), the EOO of 5-HMF to 2,5-furandicarboxylicacid (FDCA) requires a theoretical cell voltage of 0.3 V. In contrast, theoretical cell voltages of 1.23 V are required for the OER/HER [5]. With the focus on sustainable and energy-efficient systems, the simultaneous production of platform chemicals and green H2 via paired electrolysis offers high potential. [1-7]Previous studies have mainly focused on electrode materials, morphology and its electrocatalytic activity in divided batch cells. A strongly alkaline environment is considered advantageous for the electro-organic oxidation reaction, while the HER is reported to be kinetically slower in alkaline than in acidic conditions. Overall, the coupled electrolysis of H2 and platform chemicals is described as a promising technology in the development stage. [5-7]In this context, the present research explores paired electrosynthesis of platform chemicals and H2 to advance sustainable and efficient energy sources. A central goal is the prototype development of an undivided flow reactor in TRL4. Particular attention will be paid to mild operating conditions (such as a mild-alkaline environment, low operating pressures and low temperatures), PGM-free catalysts and the elimination of PFSA materials. To achieve this goal, various milestones have been defined. Among them is the development of 3D electrodes with suitable and selective catalysts. These are to be electrochemically tested in a flow-through test cell on a laboratory scale. In order to create a basis for analysis, the electrode reactions were first investigated electrochemically in a typical divided H-cell and reference measurements were carried out on nickel-based materials. In this work, NiOOH sheet and foam electrodes were electrochemically produced and subsequently investigated by cyclic voltammetry (CV) followed by bulk electrolysis. On this basis, suitable analytics (HPLC, UV-VIS) were also determined to quantify and classify the derivatives of the electrosynthesis process. These pre-experiments form the basis for the ongoing development of initial concept ideas for a modular test cell that allows various materials and structures to be electrochemically investigated.Overall, this research contributes to advancing sustainable and efficient energy sources and enabling the production of platform chemicals from renewable raw materials. Acknowledgments The authors thank the European Union’s Horizon Europe research and innovation programme under grant agreement N° 101070856 ELOBIO (Electrolysis of Biomass) for funding.

Impact of microalgal cell wall biology on downstream processing and nutrient removal for fuels and value-added products

The outlook of the production of advanced fuels and chemicals from integrated oil palm biomass biorefinery

Green chemistry is a pivotal discipline addressing the urgent need for sustainable and environmentally friendly chemical processes. This abstract highlights recent advances in the sustainable synthesis of novel organic compounds through green chemistry principles. Traditional chemical synthesis often relies on hazardous reagents, generates copious waste, and consumes substantial energy. In contrast, green chemistry promotes strategies that minimize these detrimental impacts while fostering innovation. Key advancements include the development of efficient catalytic processes, utilization of renewable feedstock’s, and the design of inherently safer chemical pathways. One notable breakthrough involves the utilization of catalysts such as enzymes, which enhance reaction selectivity and reduce energy consumption. Furthermore, the incorporation of renewable resources like biomass-derived feedstock’s not only mitigates the carbon footprint but also diversifies the sources of organic compounds. Additionally, the design of safer chemical routes with reduced toxicity and improved efficiency is gaining prominence. These sustainable approaches have led to the synthesis of novel organic compounds with applications ranging from pharmaceuticals to materials science. Green chemistry's impact extends beyond chemical synthesis, as it contributes to a cleaner environment, decreased resource depletion, and enhanced human health. As the world faces increasing environmental challenges, the pursuit of sustainable organic synthesis through green chemistry is crucial for a more sustainable and harmonious future

Abstract: Heterogeneous catalysis using continuous flow processing is one of the most demanding subjects from the viewpoint of manufacturing industrial-scale organic compounds. An amalgamation of the two areas of technology, i.e., heterogeneous catalysis and flow chemistry, has opened new avenues for green synthetic chemistry. These processes are particularly convenient in terms of short diffusion paths and improved mixing due to the sensing of high local concentration of catalytic species on solid catalytic surface when the liquid/ gaseous reagents pass through the column, ultimately resulting in quicker and more efficient reaction with increased reaction rates and higher turnover numbers. It imparts several key benefits over conventional batch systems, such as time and energy-saving methodologies, better productivity, reproducibility, economic viability, waste reduction, and ecofriendly nature. Also, it eradicates the need for any intermediate isolation, separation of catalysts, and use of excess reagents. The present review article focuses on heterogeneous catalysis under continuous flow conditions. Various key reactions, for instance, carbon-carbon bond formation, hydrogenation, condensation, and oxidation, are presented well, along with their recent developments in the manufacturing of active pharmaceutical ingredients and platform chemicals. Asymmetric catalysis has also been discussed with its applications in the synthesis of complex organic molecules. It is anticipated that the review article will proliferate significant interest in modernizing chemical syntheses through continuous flow processes.

Catalytic transformation of cellulose into short rod-like cellulose nanofibers and platform chemicals over lignin-based solid acid

Chapter 6 - Current role and future developments of biopolymers in green and sustainable chemistry and catalysis

Concerns over dwindling oil reserves, carbon dioxide emissions from fossil fuel sources and associated climate change is driving the need for clean, renewable energy supplies. If average global temperature rises induced by greenhouse gases are not to exceed 1.5 °C, then estimates indicate that a large proportion of crude oil, gas and coal reserves must remain untouched.1 Biomass, derived from agricultural and forestry residues, or non-food sources of triglycerides are a sustainable source of carbon that can provide low cost solutions for transportation fuels and organic chemicals. Akin to petroleum refining, biorefining will integrate biomass conversion processes to produce fuels, power, and chemicals, thereby increasing the economic viability of bio-derived processes. Indeed, the US DoE identified a range of sugar derived ‘Platform Chemicals’ produced via chemical or biochemical transformation of lignocellulosic biomass as potential targets for manufacture in biorefineries.2 Catalytic technologies played a critical role in the economic development of both the petrochemical industry and modern society, underpinning 90 % of chemical processes and contributing to over 20% of all industrial products. In a post-petroleum era, catalysis will underpin biorefinery technology, and researchers will need to rise to the challenge of synthesising chemical intermediates and advanced functional materials and fuels from such non-petroleum based feedstocks.3 This presentation will discuss the challenges faced in catalytic biomass processing, and highlight recent successes in catalyst design facilitated by advances in nanotechnology and careful tuning of catalyst formulation. Specific case studies will explore (i) how the effects of pore architecture and acid strength can impact upon process efficiency in biodiesel synthesis;4,5 (ii) how catalytic pre-treatments improve transportation fuel production from pyrolysis oil,6 and (iii) the role of bifunctional catalysts in the hydrodeoxygenation of phenolic components in bio-oils,7 and the aqueous phase processing of sugars to important platform chemicals and fuel precursors such as 5-HMF derivatives.8 References. 1. M. Jakob, J. Hilaire, Nature, 517 (2015) 150. 2. J.J. Bozell, G.R. Petersen, Green Chemistry, 12 (2010) 539. 3. K. Wilson, A. F. Lee Phil. Trans. R. Soc. A, 374 (2016) 20150081. 4. A.F. Lee, K Wilson, Catalysis Today, 242 (2015) 3. 5. M.A. Isaacs, C.M.A. Parlett, N. Robinson, L.J. Durndell, J.C. Manayil, S.K. Beaumont, S. Jiang, N.S. Hondow, A.C. Lamb, M.L. Johns, K. Wilson, A.F. Lee, Nature Catalysis, 3 (2020), 921. 6. L. Ciddor, J.A. Bennett, J.A. Hunns, K. Wilson, A.F. Lee J. Chem. Tech. Biotech., 90 (2015) 780. 7. A. Shivhare, J.A. Hunns, L.J. Durndell, C.M.A. Parlett, M.A. Isaacs, A.F. Lee, K. Wilson, ChemSusChem, 13 (2020), 4771. 8. A. Osatiashtiani, A.F. Lee, D.R. Brown, J.A. Melero, G. Morales, K. Wilson, Cat. Sci. Tech., 4 (2014), 333.

The need for environmentally benign reactions is very important in view of today's eco-friendly conscious attitude. “Benign by Design” represents the 12 principles of Green Chemistry as articulated by John Warner and Paul Anastas (Green Chemistry: Theory and Practice, Oxford University Press, New York, 1998, p. 30) These principles have given chemists a framework for the evaluation of the chemical procedures and help chemists to develop synthetic procedures which are more efficient, create less waste, use and produce less toxic substances. Many chemists already considered some of these principles without giving much attention. The difference between traditional chemistry and green chemistry is that the green chemistry demands issues of sustainability and environmental impact; in essence we design chemicals that are inherently more benign. In recent years, the use of solid acid catalysts such as zeolites and zeotype molecular sieve (D. W. Breck, Zeolite Molecular Sieves, Wiley, New York, 1974; A. Dyer, An Introduction to Zeolite Molecular Sieves, John Wiley & Sons, Chichester, 1988) catalysts in the manufacture of fine chemicals, chemical intermediates, drugs and drug intermediates has attracted increasing interest as green catalysts. Owing to the special features of zeolites such as shape selectivity, thermal stability, controlled variability, reusability and eco-friendly nature, these catalysts are most sought after in green chemistry. This perspective particularly illustrates the application of zeolites and zeotype catalysts for the synthesis of various N-heterocyclic compounds. For proposed reaction mechanisms see ESI.

Phase-transfer catalysis has been recognized as a powerful method for establishing practical protocols for organic synthesis, because it offers several advantages, such as operational simplicity, mild reaction conditions, suitability for large-scale synthesis, and the environmentally benign nature of the reaction system. Since the pioneering studies on highly enantioselective alkylations promoted by chiral phase-transfer catalysts, this research field has served as an attractive area for the pursuit of "green" sustainable chemistry. A wide variety of asymmetric transformations catalyzed by chiral onium salts and crown ethers have been developed for the synthesis of valuable organic compounds in the past several decades, especially in recent years.

The non-energetic valorisation of renewable resources using efficient and eco-friendly methodologies is the central axis of the “green chemistry” concept. In particular, the chemical and chemo-enzymatical transformation of carbohydrates arising from the hydrolysis of nonedible vegetal feedstock (i.e., lignocellulosic biomass) is a widely explored thematic for the production of new high-added value materials, synthons, and platform chemicals (Bozell, 2010). The use of mono-, diand polysaccharides for the production of new chemicals constitutes thus a subject of special relevance from both academic and industrial points of view (Lichtenthaler, 2004). Amongst the 12 principles defining this “green chemistry” concept, the development of new effective synthetic protocols, minimising wastes and energy-consumption while enhancing purity of the final product, is the corner stone (Anastas, 1998). In this regard, the use of microwaves as a non-conventional heating method has progressively gained attention due to commonly observed acceleration in reactions rates and improved (regioand chemo-) selectivities and yields in synthetic organic transformations (Kappe, 2004; Caddick, 2009). The claimed cleaner reaction profiles of microwave-assisted processes have thus rapidly projected this kind of heating as a popular method in chemistry, which often replaces the “classical” heating ones. Numerous organic reactions are nowadays fully depicted in the peer-reviewed literature and books. They concern typical synthetic organic approaches (substitutions, alkylations, cycloadditions, esterifications, cyclisations, etc.), organometallic reactions, oxidations and reductions, or polymerisation reactions (Bogdal, 2006).

Biorefineries are becoming increasingly important in providing sustainable routes for chemical industry processes. The establishment of bio-economic models, based on biorefineries for the creation of innovative products with high added value, such as biochemicals and bioplastics, allows the development of “green chemistry” methods in synergy with traditional chemistry. This reduces the heavy dependence on imports and assists the development of economically and environmentally sustainable production processes, that accommodate the huge investments, research and innovation efforts. This book explores the most effective or promising catalytic processes for the conversion of biobased components into high added value products, as platform chemicals and intermediates. With a focus on heterogeneous catalysis, this book is ideal for researchers working in catalysis and in green chemistry.