Chemical Engineering Distilled

The performance of CO₂ electrolysers is often limited by poor transfer of reactants and products. Here the authors design a CO₂ electrolyser in which forced convection of the catholyte throughout a porous electrode addresses this issue and allows high current densities to be reached.

Two industrial chemicals are sustainably produced at large scale by microbial gas fermentation.

Metal–organic frameworks (MOFs) are promising candidates to store hydrogen for transportation, but less focus has been on their potential for storage in large-scale, stationary applications. Here Peng et al. perform techno-economic analysis and process modelling to evaluate the prospects of MOFs for back-up power.

An air purification strategy is presented that moves air in the form of bubbles through an ion-doped conjugated polymer-coated matrix, which captures larger particulate matter, infiltrated with a selected functional liquid, which captures smaller particulate matter.

An efficient and scalable direct seawater electrolysis method for hydrogen production that addresses the side-reaction and corrosion problems associated with using seawater instead of pure water is demonstrated.

Lignin conversion to higher value products is essential to the economic viability of lignocellulosic biorefineries. Here, the authors demonstrate the bioconversion of alkali pretreated lignin to itaconic acid by dynamic two stage fermentation using a signal-amplified nitrogen-limitation biosensor.

Coupling CO₂ capture and electrolysis offers new opportunities to reduce energy cost. Here, the authors identify that the integrated electrolyser must show similar performance to the gas-fed electrolyser to ensure an energy benefit of up to 44% versus sequential capture and conversion processes.

Here the authors design an electrolysis reactor to generate H₂O₂ which could be further catalytically activated by Cu single atoms to yield hydroxyl radicals. Combining the two reactions enables a system that could treat organic wastewater, providing a path toward sustainable advanced oxidation processes.

Three alternative CO₂ emission-mitigation pathways were analysed for the global plastics sector, covering their production to waste management. A circular bioeconomy strategy could achieve negative emissions in the long term, while at the same time allowing landfilling to be phased out and reducing resource consumption.

Low-temperature CO₂ electrolysis is a promising process for producing renewable chemicals and fuels. This work provides a systematic techno-economic assessment of four major products, prioritizing technological development, and proposes guidelines to facilitate market adoption.

Solar hydrogen production devices have demonstrated promising performance at the lab scale, but there are few large-scale on-sun demonstrations. Here the authors present a thermally integrated kilowatt-scale pilot plant, tested under real-world conditions, for the co-generation of hydrogen and heat.

A versatile solar-driven hybrid photoelectrochemical platform has been developed for the simultaneous conversion of greenhouse gas CO₂ and waste plastics into value-added fuels and chemicals with high efficiency and selectivity.

Sourcing rare earth elements (REEs) from unconventional feedstocks has substantial environmental and societal–economic benefits. Here the authors develop tools to evaluate the economic viability of unconventional REE feedstocks to facilitate the implementation of a sustainable REE supply.

The decarbonization of the global iron and steel industry is important for energy systems mitigation. Using a facility-level database, this Article presents cost-effective, region-specific strategies targeting plants with a large age-to-capacity ratio and/or high emissions intensity.

Chemical upcycling of polyolefin plastic waste over metal-based catalysts is crucial for the circular economy, but currently available methods are incompatible with chlorine-contaminated feedstocks. Here the authors propose a two-stage dechlorination–hydrogenolysis (or hydrocracking) upcycling strategy to tackle this problem.

Catalysts consisting of oxide-supported pair sites can enable bifunctional reaction mechanisms with high activity and selectivity for reactions and so overcome the limitations in industry imposed by the use of homogeneous catalysts.

The dynamic transformation of Cu ions during the selective catalytic reduction of NO_x on Cu zeolites is well documented, although the function of the zeolite framework has not been fully understood. Here the authors unravel the role of anionic Al sites in the zeolite framework in regulating the mobility and reactivity of Cu cations during catalysis.

An accurate evaluation of lithium-metal battery performance is challenging due to the excessive lithium that is often used at the anode. Here the authors report a methodology to assess the degradation mechanism and cycle life of practical lithium-metal batteries.

Carbon-neutral hydrogen can be produced through photocatalytic water splitting, as demonstrated here with a 100-m² array of panel reactors that reaches a maximum conversion efficiency of 0.76%.

Manipulating the properties of polymeric thin films independent of their chemistry is challenging. Now, a vapour solvation strategy is introduced to achieve targeted properties, including molecular weight, mechanical strength and film morphology, without the need for chemical modification.

Ni–Fe carbon monoxide dehydrogenases (CODHs) are able to oxidize CO with a high rate, but their O₂ sensitivity is a major drawback for their industrial application. This work shows that CODHs can be tailored for industrial or gas cleaning processes by engineering the selectivity of their gas channels.

Renewable biomass conversion may afford high-value products from common materials, but catalysts usually require expensive metals and exhibit poor selectivities. Here, authors employ nickel-iron oxide and nitride electrocatalysts to produce H₂ and to convert glucose to glucaric acid selectively.

A combination of electronic structure calculations and machine learning strategies is developed to predict structures of complex heterogeneous catalysts in realistic environments, yielding new opportunities for optimization for energy applications.

Plastic waste poses a serious economic, ecological and environmental threat. Here, non-recyclable, post-consumer microplastics are used as an electron feedstock for biosynthetic reactions in a photoelectrocatalytic system. The microplastics are simultaneously broken down into organic fuels, meaning that this system provides valuable chemicals at both the anodic and cathodic sites.

The performance of nanostructured metal catalysts in acetylene hydrochlorination is governed by an interplay of nuclearity, coordination and host effects. The central activity descriptor is identified as the acetylene adsorption energy.

A depolymerization method is described that uses electrified spatiotemporal heating to selectively generate monomers from the commodity plastics polypropylene and poly(ethylene terephthalate), allowing control over the pyrolysis of plastic waste and reducing the formation of side products.

Analysis of a large dataset of scanning transmission X-ray microscopy images of carbon-coated lithium iron phosphate nanoparticles shows that the heterogeneous reaction kinetics of battery materials can be learned from such videos pixel by pixel.

Spillover phenomena are crucial in heterogeneous catalysis, yet remain elusive to quantitative characterization. Here the authors measure the surface concentration of hydrogen spilling-over onto TiO₂ using Au/TiO₂ catalysts and explain the underlying factors governing the process.

We report a small-organic-molecule oscillator that catalyses an independent chemical reaction in situ without impairing its oscillating properties, allowing the construction of complex systems enhancing applications in automated synthesis and systems and polymerization chemistry.

Bisphenol A (BPA) is an essential building block for manufacturing plastics, but its adverse health effects have become a major concern. Here the authors show a zeolite-catalysed synthetitic route to bio-renewable BPA alternatives that feature excellent safety and preserve efficacy of function.

To overcome mass transport limitations in zeolite-catalysed reactions, scientists must often resort to hierarchical or nanosized zeolites; however, the synthesis of such materials remains challenging. Here the authors disclose a one-pot method for the preparation of Si-zoned MFI-type catalysts with improved diffusion properties for the methanol-to hydrocarbon reaction.

Semipermeable polymeric anion exchange membranes are essential for separation, filtration and energy conversion technologies such as fuel cells. Quasi-elastic neutron scattering is now used to disentangle water, polymer relaxation and OH⁻ diffusional dynamics in a commercially available membrane.

The demands of sustainable energy supply and clean water production continue to drive membrane development. Here the authors design graphene oxide membranes intercalated with polyaromatic cations that not only exhibit sustained nanofiltration performance under realistic conditions but also are scalable for industrial applications.

Modification of the internal and external surface chemistry of microporous zeolite and metal–organic framework nanocrystals leads to a generalizable strategy to aqueous porous liquids and impart high gas-carrying capacities to liquid water.

Membranes can be used not only for water filtration but also for solute–solute separation. Using the separation between lithium and magnesium, this analysis provides a platform for evaluating the performance of nanofiltration-based selective solute separation.

The practical optimizations of heterogeneous catalytic processes and reactor engineering are intertwined, but often what occurs inside the reactor remains elusive. Now, the molecular diffusion and carbon number of hydrocarbon products during Fischer–Tropsch synthesis on a Ru/TiO₂ catalyst are spatially resolved via magnetic resonance imaging in a pilot-scale fixed-bed reactor.

Carbon molecular sieves (CMS) are formed from pyrolysis of polymeric precursors, forming complex morphologies that enable gas separations. Here, by combining kinked and cross-linkable structures in the precursor, CMS membranes are reported that enable a broad spectrum of challenging gas separations.

The separation of butane isomers, raw materials in petrochemical industry, is challenging. Here the authors report the separation of n-butane and isobutane using a metal-organic framework slurry; the separation can be performed at large scale in a pilot-scale separation tower.

Theoretical and experimental analysis of the effect of grain shape in bed load sediment transport is performed and a shape-corrected sediment transport law that provides greater accuracy in predictions is proposed.

Electrochemical approaches to carbon capture have the advantages of operation under ambient conditions and modular design, but improved sorbent molecules are still needed. Here the authors present a library of redox-tunable Lewis bases, shedding light on molecular design guidelines to tune sorbent properties.

Lithium mining is both energy and land intensive. The use of a 3D porous natural cellulose fibre structure enables an interfacial crystallization method for the selective extraction of lithium from both brine and seawater that can be a significant alternative to mining.

Turbulence can be reduced by more than 25% in ordinary pipe flow by unsteady, pulsatile driving specifically mimicking the cardiac cycle and extending this method to large Reynolds numbers.

The authors develop a strategy that allows the diffusion limit of ions in water to be approached for large-area, free-standing, synthetic membranes using covalently bonded polymer frameworks with rigidity-confined ion channels.

Although gas bubble dynamics during electrochemical processes dramatically affect performance, the fundamental understanding and manipulation of such dynamics have been limited. Now, electrolyte composition is found to be a key factor in inducing a solutal Marangoni instability that impacts both H₂ gas detachment and coalescence between H₂ microbubbles.

Atmospheric water harvesting is challenging due to the presence of airborne pollutants. The authors show a device design that enables fog capture with simultaneous pollutant decomposition powered by sunlight.

Enzymes for poly(ethylene terephthalate) (PET) deconstruction are of interest for plastics recycling, but reports on their directed evolution are missing. Now, an automated, high-throughput directed evolution platform is described, affording HotPETase that effectively achieves depolymerization above the glass transition temperature of PET.

Eukaryotic cytochrome P450s (P450s) are often required for the biosynthesis of natural products, but their performance in bacteria is usually reduced. Now, scaffold enzymes bring eukaryotic P450s and a reductase in close proximity for efficient electron channelling, increasing the production of natural products in Escherichia coli.

Wet-dry cycling is thought to have enabled the production of molecular building blocks of life. Here, the authors investigate the impact of dehydration/rehydration on RNA-containing complex coacervates, which are membraneless compartments formed by phase separation of polyelectrolyte solutions.

Muconic acid is a platform chemical with wide industrial applicability. Here, the authors report efficient muconate production from glucose and xylose by engineered Pseudomonas putida strain using adaptive laboratory evolution, metabolic modeling, and rational strain engineering strategies.

Organoids recapitulate many aspects of native tissues and even display tissue and organ-level functionality, although with limited control over morphogenesis. This Review describes an emerging framework, termed middle-out tissue engineering, that facilitates spatiotemporal control of tissue-specific cell niches to enable deterministic organoid self-organization and build more advanced in vitro tissue models.

Star-shaped, approximately 1-mm-wide ceramic particles, termed STAR particles, create micropores in the skin and, when added to topical formulations, enhance drug and vaccine delivery through the skin in mice.

Natural products are produced by living organisms practising nature’s chemical transformations. Now, an unnatural product has been generated by creating hybrid biosynthetic microorganisms. These microorganisms combine an unnatural chemical transformation—catalysis by an artificial metalloenzyme containing an iridium-based, unnatural cofactor—with a natural biosynthetic pathway within the same cell.

Viscoelasticity is a universal mechanical feature of the extracellular matrix. Here the authors show that the extracellular matrix viscoelasticity guides tissue growth and symmetry breaking, a fundamental process in morphogenesis and oncogenesis.

Biomolecular condensates with internal structure allow cells to further organise their processes. In this work the authors investigate how condensates can obtain an internal structure with droplets of dilute phase inside via kinetic, rather than purely thermodynamic driving forces.

Polyketide yields in Streptomyces are boosted by routing stored intracellular triacylglycerol into pathways that make industrially relevant products.

The rational design of out-of-equilibrium demixing transitions remains challenging. Active fluids are used to control the liquid–liquid phase separation of passive DNA nanostars and establish the activity-based control of the phase diagram.

Microbial production of oleochemicals involves strategies of expressing thioesterase to narrow the substrate pool for the termination enzyme at the expense of one ATP. Here, the authors developed an alternative energy-efficient strategy to use of an acyl-ACP transacylase to produce medium chain oleochemicals in E. coli.

Plastic pollution is rapidly increasing worldwide, causing adverse impacts on the environment, wildlife and human health. Here the authors present a synthetic microbial consortium that efficiently degrades polyethylene terephthalate hydrolysate and upcycles it to desired chemicals through cellular division of labor.

Two highly charged disordered human proteins phase-separate into viscous complex coacervates while retaining their rapid conformational dynamics through pico- to nanosecond exchange of short-lived side-chain interactions.

Adenosylcobalamin (AdoCbl) is an essential vitamin whose production is limited to bacterial fermentation. Here, the authors report an alternative method for the synthesis of AdoCbl based on a cell-free reaction system integrating more than 30 biocatalytic reactions to produce AdoCbl from 5-aminolevulinic acid.