Status and perspectives of CO2 conversion into fuels and chemicals by catalytic, photocatalytic and electrocatalytic processes

Alcohol Production from Carbon Dioxide: Methanol as a Fuel and Chemical Feedstock

This comprehensive review explores the potential of radio frequency (RF) induction heating in chemical reactions, explicitly focusing on magnetically induced catalysis using magnetic nanoparticles (NPs). We trace the recent historical progress of induction heating and highlight the advancements in liquid and gas‐phase reactions, particularly in its integration with heterogeneous catalysis. The review finds that induction heating profoundly impacts reaction kinetics, and selectivity, and can even reduce overpotentials in electrocatalytic processes. A final outlook unveils the challenges and opportunities associated with aspects such as fundamental research and reactor design, with a particular focus on expanding its use to higher pressures and necessary optimizations to improve energy efficiency. Moreover, it highlights the pressing need for standardized reporting in induction‐heated catalysis. The study underscores the significance of this brand‐new field in developing efficient and sustainable catalytic processes, which are essential for meeting the growing demand for clean energy and sustainable chemical production.

Chemical sciences and engineering have made outstanding contributions in fulfillment of the needs of our technological society and upliftment of the quality of human life by enabling critical technologies for processing and manufacturing of high-volume essential commodities such as detergents, creams, sanitizers, pharmaceuticals, textiles, plastics, rubbers and so on. The global models of chemical manufacturing have been continuously evolving since the colonial rule to adapt to the socio-economic and political climate. In the face of the twenty-first century, chemical manufacturing is experiencing global challenges of different kinds ranging from depletion of natural resources, climate change and growing population to sustainable living, environmental compliance, and personalized healthcare. Thus, a great need has been felt for reinvigoration of the chemical processing and manufacturing industry in response to which the philosophies of industry 4.0 and smart manufacturing have seen global acceptance and recognition. However, this transcendence from the existing state of chemical manufacturing to smart manufacturing heavily relies on the availability and development of advanced manufacturing and sophisticated equipment, process intensification and efficient micro reaction technologies. Study, design, and engineering of equipment to manipulate chemical and physical phenomenon is at the heart of chemical engineering since equipment and reactor design directly governs process and energy efficiencies, performance, and process economics. Conventional subtractive and casting based manufacturing technologies are proving inadequate to meet the needs of modern chemical engineering demanding capabilities to fabricate sophisticated equipment with complex internal geometries, rapid prototyping, and performance testing. These manufacturing related issues can be effective phased out with the adoption and integration of additive manufacturing with chemical processing and manufacturing industries. While the automotive, aerospace, engineering and biomedical industries have hastily adopted AM technologies for associated benefits, the chemical industries have been lagging behind in the uptake due to lack of agility and adaptability in industrial chemical processes. Integration of AM with chemical industry is anticipated to bring widespread process automation, improved feedstock and product inventories, digital process control and process intensification. Future chemical reactors will be complex tailor-made devices with design optimized for fluid and particle flow, heat and mass transport and reaction thermodynamics. When reactions are catalytic in nature, the performance of the reactor becomes critically dependent on several of the catalyst properties, both physical and chemical. While the intrinsic chemical properties in terms of selectivity and activity are dependent on the choice of catalyst, other important considerations related to reactor efficiencies and design, are related to the structural properties of the catalyst, i.e., on how the active phase of the catalyst is dispersed in the support, that influences the available surface area, porosity, heat, and mass transfer characteristics as well as the hydrodynamic pressure dissipations. This aspect of structured catalytic reactor design, that is based on a functional integration of the catalytic as well as reactor design steps, is also receiving increasing focus from an advanced manufacturing viewpoint towards achieving higher efficiencies and lower energy consumption. In this chapter the role of additive manufacturing in chemical reactor and equipment design ranging from simulation and reactor modelling to demonstrated examples of additively manufactured micro mixers, micro heat exchanges and microreactors are elaborated which distinctly project additive manufacturing as the future of green chemical engineering.KeywordsIndustry 4.0Smart manufacturingProcess intensificationMicro reaction technologyAdditive manufacturingGreen hydrogen

Conversion of the greenhouse gas CO2 into carbon and useful carbon sources such as CO, HCOOH, HCHO, CH3OH, and CH4 is a potential method of solving energy and environmental problems. Photocatalytic conversion of manmade CO2 is attractive from the viewpoint of sustainable energy production and greenhouse gas reduction. Layered double hydroxides (LDH) are synthetic or natural crystalline clays that consist of brucite (Mg(OH)2)-like positively charged two-dimensional sheets in which some divalent cations such as Mg2+ are substituted by trivalent cations; further, water and exchangeable charge-compensating anions are present in the interlayer. In this study, we carried out the photocatalytic conversion of CO2 in H2O using various LDHs. Considerable amount of CO was obtained over various LDHs in the photocatalytic conversion of CO2 and photocatalytic H2 evolution from H2O competitively took place in all cases. Ni-Al LDH exhibited high selectivity to CO because the amount of H2 evolved was relatively low. Ni-Al LDH (Ni/Al = 4) which was aged for 20 h under hydrothermal condition at 383 K after coprecipitation showed the highest activity for the evolution of CO. GC/MS analysis for the photocatalytic conversion of 13C-labeled CO2 clarified that 13CO (m/z = 29) was evolved in priority to 12CO (m/z = 28). Accordingly, CO2 introduced in the gas phase was adsorbed on the surface of LDHs, and then reduced into CO in the photocatalytic conversion of CO2 in water.

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The pressing climate change issues have intensified the need for a rapid transition towards a bio-based circular carbon economy. Harnessing acetogenic bacteria as biocatalysts to convert C1 compounds such as CO2, CO, formate, or methanol into value-added multicarbon chemicals is a promising solution for both carbon capture and utilization, enabling sustainable and green chemical production. Recent advances in the metabolic engineering of acetogens have expanded the range of commodity chemicals and biofuels produced from C1 compounds. However, producing energy-demanding high-value chemicals on an industrial scale from C1 substrates remains challenging because of the inherent energetic limitations of acetogenic bacteria. Therefore, overcoming this hurdle is necessary to scale up the acetogenic C1 conversion process and realize a circular carbon economy. This review overviews the acetogenic bacteria and their potential as sustainable and green chemical production platforms. Recent efforts to address these challenges have focused on enhancing the ATP and redox availability of acetogens to improve their energetics and conversion performances. Furthermore, promising technologies that leverage low-cost, sustainable energy sources such as electricity and light are discussed to improve the sustainability of the overall process. Finally, we review emerging technologies that accelerate the development of high-performance acetogenic bacteria suitable for industrial-scale production and address the economic sustainability of acetogenic C1 conversion. Overall, harnessing acetogenic bacteria for C1 valorization offers a promising route toward sustainable and green chemical production, aligning with the circular economy concept.

Chapter 11 - Production of fine chemicals from renewable feedstocks through the engineering of artificial enzyme cascades

Assessing the potential of CO2 utilization with an integrated framework for producing power and chemicals

Review: 305 refs.

The transition from a fossil fuel-based economy to a bio-based economy necessitates the exploitation of synergies, scientific innovations and breakthroughs, and step changes in the infrastructure of chemical industry. Sustainable production of chemicals and biopolymers should be dependent entirely on renewable carbon. White biotechnology could provide the necessary tools for the evolution of microbial bioconversion into a key unit operation in future biorefineries. Waste and by-product streams from existing industrial sectors (e.g., food industry, pulp and paper industry, biodiesel and bioethanol production) could be used as renewable resources for both biorefinery development and production of nutrient-complete fermentation feedstocks. This review focuses on the potential of utilizing waste and by-product streams from current industrial activities for the production of chemicals and biopolymers via microbial bioconversion. The first part of this review presents the current status and prospects on fermentative production of important platform chemicals (i.e., selected C2-C6 metabolic products and single cell oil) and biopolymers (i.e., polyhydroxyalkanoates and bacterial cellulose). In the second part, the qualitative and quantitative characteristics of waste and by-product streams from existing industrial sectors are presented. In the third part, the techno-economic aspects of bioconversion processes are critically reviewed. Four case studies showing the potential of case-specific waste and by-product streams for the production of succinic acid and polyhydroxyalkanoates are presented. It is evident that fermentative production of chemicals and biopolymers via refining of waste and by-product streams is a highly important research area with significant prospects for industrial applications.

Bio-based production of industrially important chemicals and materials from non-edible and renewable biomass has become increasingly important to resolve the urgent worldwide issues including climate change. Also, bio-based production, instead of chemical synthesis, of food ingredients and natural products has gained ever increasing interest for health benefits. Systems metabolic engineering allows more efficient development of microbial cell factories capable of sustainable, green, and human-friendly production of diverse chemicals and materials. Escherichia coli is unarguably the most widely employed host strain for the bio-based production of chemicals and materials. In the present paper, we review the tools and strategies employed for systems metabolic engineering of E. coli. Next, representative examples and strategies for the production of chemicals including biofuels, bulk and specialty chemicals, and natural products are discussed, followed by discussion on materials including polyhydroxyalkanoates (PHAs), proteins, and nanomaterials. Lastly, future perspectives and challenges remaining for systems metabolic engineering of E. coli are discussed.

Research in the field of photochemistry, including photocatalysis and photoelectrocatalysis, has been revitalized due to the potential that photochemical reactions show in the sustainable production of chemicals. Therefore, there is a need for flexible photoreactor equipment that allows for the evaluation of the geometry, light wavelength, and intensity of the vessel, along with the fluid flow in various photochemical reactions. Light emitting diodes (LEDs) have narrow emission spectra and can be either pulsed or run continuously; being flexible, they can be arranged to fit the dimensions of various types of the reactor vessel, depending on the application. This study presents a 3D printed photoreactor with the ability to adjust distances easily and switch between high-power LED light sources. The reactor design utilizes customized printed circuit boards to mount varying numbers and types of LEDs, which enables multiple wavelengths to be used simultaneously. These LED modules, comprised of heat sinks and cooling fans, fulfill the higher heat dissipation requirements of high-power LEDs. The flexibility of the reactor design is useful for optimizing the reaction geometry, flow conditions, wavelength, and intensity of photochemical reactions on a small scale. The estimates for incident light intensity under five possible reactor configurations using ferrioxalate actinometry are reported so that comparisons with other photoreactors can be made. The performance of the photoreactor for differing vessel sizes and distances, in both the flow and batch modes, is given for a photochemical reaction on 2-benzyloxyphenol-a model substance for lignin and applicable in the production of biobased chemicals.

HI-Light: A Glass-Waveguide-Based "Shell-and-Tube" Photothermal Reactor Platform for Converting CO2 to Fuels.

Over the past decade, great efforts have been devoted in the field of biomass valorization to the development of reductive processes for the sustainable production of bio-fuel and chemicals. Catalytic transfer hydrogenation, which uses alcohols as the hydrogen source, offers an interesting approach that avoids the use of both high H2 pressure and precious metal catalysts. In this work, the vapour-phase production of furfuryl alcohol (FAL) and 2-methylfuran (MF) from biomass-derived furfural (FU), using methanol as the H-transfer agent was studied. Two class of catalysts were employed: basic-based systems such as MgO, Mg/Fe/O, Mg/Al/O and CaO; and a mixed iron-vanadium oxide FeVO4. With the latter at the temperature of 320°C it was possible to achieve 80% yield to 2-methylfuran, with small amounts of 2,5-dimethylfuran (DMF) and 2-vinylfuran (VINFU) as by-products. The study of the reaction network permitted us to infer on the relative contribution of H-transfer and hydrogenation, to 2-methylfuran formation. On the other hand, with the basic-base catalysts, it was demonstrated that both the pristine systems MgO and CaO were totally selective towards the formation of the unsaturated alcohol FAL as the only reduction product of FU at mild temperature condition, thus allowing selective H-transfer from methanol to the substrate. Conversely, the distribution of compounds obtained with Mg/Fe/O was significantly different, with 2-methylfuran formation prevailing when the reaction was carried out between 300 and 400 °C. Furthermore the use of different hydrogen sources such as 2-propanol, acetone, acetaldehyde, formaldehyde and molecular hydrogen allow to identify the complete reaction network for the vapor-phase transformation of FU, demonstrating that both the in-situ produced molecular hydrogen and formaldehyde played a direct role in MF formation. The reported results indicate the potential application of the catalytic transfer hydrogenation reaction as an efficient process for the selective de-oxygenation of biomass-derived molecules.

The emergence of single atom sites as a frontier research area in catalysis has sparked extensive academic and industrial interest, especially for energy, environmental and chemicals production processes. Single atom catalysts (SACs) have shown remarkable performance in a variety of catalytic reactions, demonstrating high selectivity to the products of interest, long lifespan, high stability and more importantly high atomic metal utilization efficiency. In this review, we unveil in depth insights on development and achievements of SACs, including (a) Chronological progress on SACs development, (b) Recent advances in SACs synthesis, (c) Spatial and temporal SACs characterization techniques, (d) Application of SACs in different energy and chemical production, (e) Environmental and economic aspects of SACs, and (f) Current challenges, promising ideas and future prospects for SACs. On a whole, this review serves to enlighten scientists and engineers in developing fundamental catalytic understanding that can be applied into the future, both for academia or valorizing chemical processes.