Sustainable Production Of Chemicals Research Articles

Merger of Single-Atom Catalysis and Photothermal Catalysis for Future Chemical Production.

Photothermal catalysis is an emerging field with significant potential for sustainable chemical production processes. The merger of single-atom catalysts (SACs) and photothermal catalysis has garnered widespread attention for its ability to achieve precise bond activation and superior catalytic performance. This review provides a comprehensive overview of the recent progress of SACs in photothermal catalysis, focusing on their underlying mechanisms and applications. The dynamic structural evolution of SACs during photothermal processes is highlighted, and the current advancements and future perspectives in the design, screening, and scaling up of SACs for photothermal processes are discussed. This review aims to provide insights into their continued development in this rapidly evolving field.

Dissociation extraction: Theoretical foundations and applications

Dissociation extraction (DE) is a separation method that has been known for many decades but is not yet widely used in industry. However, there are a number of applications for which DE may be applied, for example, for new biorefinery separations. To facilitate future applications, we derived a new shortcut method for DE processes and demonstrated its application in the conceptual design of a separation process for acidic and basic organic mixtures. The new method allows for the calculation of the minimum energy requirement and a fast comparison of dissociation extraction with other separation methods. The shortcut method was validated using experimental data from the literature and is easy to implement because it is based only on the physical distribution coefficients and dissociation constants of the acids or bases to be separated.In the second part of this paper, we identify several areas that require effective separation techniques, where dissociation extraction can have an impact. These include biorefinery separation, polymer recycling, and fatty acid fractionation.In conclusion, we hope to promote DE as a known but less-used separation method for difficult separation problems in both fossil-based and bio-based sustainable chemical products.

Structure-Reactivity- and Modelling-Relationships during Thermal Annealing in Biomass Entrained-Flow Gasification: The Effect of Temperature and Residence Time

Biomass entrained-flow gasification enables the sustainable production of chemicals and liquid fuels. For reliable and accurate gasifier operation and design, the analysis of biomass char reactivity represents one of the key studies. Therefore, the annealing-induced char reactivity loss needs to be investigated for biogenic feedstocks from microscopic to reactor level. In the present work, the influence of pyrolysis temperature and particle residence time on solid digestate char reactivity and structure is studied. Several char types are prepared in a pressurized entrained-flow reactor between 1200 °C and 1600 °C with varying residence times between 0.4–2.4 s. Isothermal char reactivity in O2 and CO2 atmosphere is measured by TGA and reactivities are determined. Strong char deactivation between 1200 °C and 1400 °C resulted from severe heat treatment, especially toward the CO2 reaction. At 1600 °C, the influence of residence time becomes less relevant since all measured reactivities are comparably low. Experimental data are fitted to a coal deactivation model and verified for biogenic residues with very good agreement. The results are further corroborated by char structure analysis using FT-IR, XRD, Raman spectroscopy, SEM-EDX and ETV-ICP-OES. The decrease in char reactivity is mainly attributed to graphitization and the formation of aromatic ring structures. Char deactivation is further promoted by the loss of catalytic mineral matter and by high concentrations of inhibiting elements like phosphorus.

Facet-dependent spatial separation of dual cocatalysts on MOF photocatalysts for H2O2 production coupling biomass oxidation with enhanced performance

Cooperative coupling of photocatalytic two-electron oxygen reduction reaction (2e-ORR) with oxidative organic synthesis holds great promise for sustainable production of valuable chemicals. To achieve high performance, the rational design of photocatalysts with effective electron-hole separation and redox capability is crucial. Herein, a MOF-based photocatalyst with crystal facet-dependent spatial separation of dual cocatalysts is constructed for photocatalytic 2e-ORR coupled with vanillyl alcohol oxidation reaction (VAOR). The facet-dependent growth of reductive Pd and oxidative CoOx cocatalysts respectively on the {100} and {001} facets of MIL-125-NH2 enables the directional migration of photogenerated carries, facilitating the charge separation for redox reactions. Additionally, the interaction between Pd and MIL-125-NH2 modulates the Pd sites into electron-sufficient state with upshifted d-band center, promoting the O2 activation and *OOH intermediate formation. The rationally designed composite photocatalyst delivers an excellent H2O2 yield of 74.8 mM g−1 h−1 and a high vanillic acid production rate of 80.9 mM h−1 g−1 with the conversion and selectivity of 96.8 % and 91.1 %, respectively.

Pd Nanoparticles Decorated CeZrOx for Enhanced Photocatalytic Hydrogenation of Biomass‐Derived Compounds

AbstractThe photocatalytic conversion of biomass‐derived compounds into value‐added chemicals presents a promising protocol for the sustainable production of renewable chemicals. Our study explores the hydrogenation of biomass model compounds under visible light illumination. Zr was incorporated into the CeO2 framework, forming a CeZrOx(1:0.5) solid solution, confirmed by powder X‐ray diffraction (PXRD) and X‐ray photoelectron spectroscopy (XPS) analyses. The light uptake capacity of the CeZrOx solid solution was characterized using UV–visible spectroscopy. Additionally, the band structure of the CeZrOx solid solution was assessed using valance band X‐ray photoelectron spectroscopy (VB‐XPS) and Ultraviolet photoelectron spectroscopy (UPS) analysis, revealing a Z‐Scheme, which was further confirmed by various control experiments. Upon decorating the CeZrOx(1:0.5) solid solution with 1 wt% palladium (Pd), the resulting 1Pd/CeZrOx(1:0.5) composite exhibited improved charge separation and enhanced visible light absorption capacity. This composite achieved ∼99% conversion of furfural to tetrahydrofurfuryl alcohol under a 15 W blue LED illumination and 0.2 MPa hydrogen. Similarly, it demonstrated ∼99% conversion of benzyl phenyl ether (BPE) to toluene and phenol under a 10 W blue LED illumination. Our findings elucidate the active sites and demonstrate the recyclability of mixed metal oxides for selective furfural hydrogenation and BPE hydrogenolysis under visible light.

Highly stable Co@BC catalysts encapsulated in biochar for efficient lignin hydrogenolysis to valuable monophenols

The development and utilization of renewable lignin from industrial crops to produce high-value bio-based chemicals and fuels is of great significance in reducing dependence on fossil resources and promoting green chemistry. However, conventional metal-supported catalysts often suffer from poor metal dispersion and particle agglomeration during lignin conversion, resulting in insufficient catalytic activity. To address these challenges, a novel biochar-encapsulated cobalt catalyst (Co@BC) was developed in this study for efficient lignin hydrogenolysis. The catalyst formed a unique thin carbon layer structure by encapsulating cobalt nanoparticles in biochar, which enhanced metal dispersion and prevented particle agglomeration. The performance of the catalysts was systematically evaluated at different calcination temperatures. Co@BC-650 showed the best results with a lignin liquefaction degree of 79.7 % and a monophenol yield of 19.1 wt%. This yield was significantly higher than that of the supported Co/BC-650 catalyst, which only reached 15.4 wt%. The thin carbon layer not only facilitated the reduction of cobalt species at 650 °C, but also provided antioxidant protection and maintained the stability of metallic cobalt, which was essential for H2 adsorption and activation. In addition, Co@BC-650 exhibited excellent stability with little loss of activity after 3 cycles. This study provides an efficient and sustainable method for the selective production of monophenols from renewable lignin from industrial crops, which has the potential to be widely applied for biomass conversion and large-scale sustainable chemical production.

Hydrothermal liquefaction of diverse plastics using water and seawater

In this study, a variety of plastics are converted to their monomers, fuel range hydrocarbons and other platform chemicals using hydrothermal liquefaction (HTL) at sub-critical (350 °C), near-critical (400 °C) and super-critical (450 °C) temperatures. The effect of seawater as a medium on the HTL of plastics is also studied. Polymers like polycarbonate (PC), acrylonitrile–butadiene–styrene (ABS), polyamides (PA-6, PA-66), and polyoxymethylene (POM) liquefied effectively at 350 °C, while polyolefins like polyethylene (PE) and polypropylene (PP) required ≥ 400 °C. HTL of polystyrene (PS) resulted in the highest oil yield (93 wt%) and energy recovery from oil (93.5 %) at 450 °C. HTL of PC, PS and ABS led to the formation of phenols and benzene derivatives, while polyethylene terephthalate (PET) and PA-6 formed their monomers terephthalic acid and caprolactam, respectively. Crude oils from PP and PE contained fuel grade aliphatic hydrocarbons with carbon chain length ranging between C7 and C36. Highest calorific value was recorded for the oil from PP (46.3 MJ kg−1) at 400 °C. The use of seawater generally reduced the oil yields from all the plastics, except ABS, PET and PP. The production of benzoic acid from PET was enhanced, while the selectivity to caprolactam from PA-6 decreased when seawater was used, possibly due to the enhanced decarboxylation and aromatization reactions induced by the ions in the aqueous phase. In general, the crude oil from HTL of PC, PS, ABS and polyamides are suitable for sustainable production of specialty chemicals and monomers, while that from PE and PP are good candidates for sustainable transportation fuels.

Active Sites for CO2 Hydrogenation to Methanol: Mechanistic Insights and Reaction Control.

Catalytic CO2 conversion to methanol is a promising way to extenuate the adverse effects of CO2 emission, global warming and energy shortage. Understanding the fundamental features of CO2 activation and hydrogenation at the molecular level is essential for carbon utilization and sustainable chemical production in the current climate crisis. This review explores the recent advances in understanding the design of catalysts with desired active sites, including single-atom, dual-atom, interface, defects/vacancies and promoters/dopants. We focused on the design of various catalytic systems to enhance their catalytic performances by stabilizing active metal in a catalyst, identifying the unique structure of active species, and engineering coordination environments of active sites. Mechanistic insights provided by advanced operando and in situ spectroscopies were also discussed. Moreover, the review highlights the key factors affecting active sites and reaction mechanisms, such as local environments, oxidation states, and metal-support interactions. By integrating recent advancements and relating knowledge gaps, this review aims to endow an inclusive overview of the field and guide future research toward more efficient and selective catalysts for CO2 hydrogenation to methanol.

TM and P dual sites on polymeric carbon nitride enable highly selective CO reduction to C2 products with low potentials: A theoretical perspective.

The CO reduction reaction (CORR) for the production of high-value-added multi-carbon (C2+) products is currently being actively investigated, where searching for high-efficiency catalysts with moderate CO intermediate binding strength and low kinetic barrier for C-C coupling poses a significant challenge. In this study, we employed density functional theory computations to design four synergistic coupling dual sites catalysts for CORR to C2 products, namely, TM-P@melon, by co-doping transition metals (TM = Mn, Fe, Co, and Ni) and phosphorus (P) into the polymeric carbon nitride (i.e., melon-CN). Mn-P@melon and Ni-P@melon exhibit higher selectivity toward C2H5OH and C2H6, respectively, with limiting potentials (C-C coupling kinetic energy barriers) of -0.43V (0.52eV) and -0.17V (0.26eV), respectively. The introduction of TM and P atoms not only narrows the band gap of melon-CN but also favors the coupling of CO and *CHO, providing an active site for C-C coupling, thus facilitating the catalytic reaction. Our work provides rational insights for the design of stable, low-cost, and efficient CORR dual sites catalysts that facilitate the sustainable production of high-value C2 chemicals and fuels.

In situ formation of oxygen-deficient WO3-x nanosheets for enhanced photocatalytic activity in water splitting and plastic reforming

Photocatalytic pathways are essential for the sustainable production of chemicals and fuels, pivotal for achieving a pollution-free planet. Electron-hole recombination is a critical problem that has, so far, limited the efficiency of the photocatalytic materials. Here, oxygen-deficient WO3-x nanosheets were in situ grown in a polymeric carbon nitride (PCN) support during the thermal polycondensation of melamine. The introduction of defect in WO3-x, accompanied by spin polarization and the formed WO3-x/PCN heterostructure, greatly accelerated the charge separation and transfer. The synthesized WO3-x/PCN composite exhibited a tenfold increase in hydrogen generation activity than pure PCN under visible-light (420 ≤ λ ≤ 780 nm). The WO3-x/PCN also demonstrated consecutive 24 h and stable photocatalytic H2 production in the aqueous plastic-containing [poly(vinyl alcohol) (PVA), poly(ethylene terephthalate) (PET) and the PET bottle] solutions under visible light. The hydrogen production rates were determined to be 111.2, 50.5, and 7.8 μmol·h−1·g−1 in PVA, PET and PET bottle, respectively. In addition, the oxygen vacancies WO3 with their localized surface plasmon resonance effect, facilitated efficient utilization of NIR photon and the hydrogen evolution rate over WO3-x/PCN reached to 120 μmol h−1·g−1 under NIR light (700 ≤ λ ≤ 780 nm). This research not only advances the potential applications of WO3-x/PCN in sustainable energy production but also provides insights into environmental remediation through the conversion of plastic wastes.

Efficient Production of Platform Chemicals from Lignocellulosic Biomass by Using Nanocatalysts: A Review

This paper discusses significant advancements in using lignocellulosic biomass for the sustainable production of biofuels and chemicals. As fossil-based resources decline and environmental concerns rise, the paper emphasizes the role of integrated biorefineries in producing renewable liquid fuels and high-value chemicals from biomass. It highlights exploring various green pathways for biomass conversion, with a particular focus on nanocatalysis. Due to their large surface area-to-volume ratio, nanocatalysts provide enhanced catalytic activity and efficiency in biomass transformation processes. The review delves into the synthesis of value-added and furfural platform chemicals alongside the hydrogenolysis of 5-hydroxymethylfurfural (5-HMF) into biofuels like 2,5-dimethylfuran (DMF) and 2,5-dimethyltetrahydrofuran (DMTHF). The paper ultimately underscores the importance of nanotechnology in achieving high yield and selectivity in the biomass conversion process, positioning it as a promising approach for future sustainable energy and chemical production.

Metabolic Versatility of acetogens in syngas Fermentation: Responding to varying CO availability.

Syngas fermentation using acetogenic bacteria offers a promising route for sustainable chemical production. However, gas-liquid mass transfer limitations and efficient co-utilization of CO and H2 pose significant challenges. This study investigated the kinetics of syngas conversion to acetate by Acetobacterium wieringae and Clostridium species in batch conditions under varying initial CO partial pressures (19 - 110 kPa) in batch cultures. A. wieringae strains, exhibited superior growth in all gas compositions, with a maximum growth rate of 0.104 h-1. The distinct CO, H2, and CO2 consumption patterns revealed metabolic flexibility and adaptation to varying syngas compositions. Notably, A. wieringae strains and C. autoethanogenum achieved complete CO and H2 conversion, with C. autoethanogenum also exhibiting net CO2 uptake. These findings provide valuable insights into the distinct metabolic capabilities of these acetogens and contribute to the development of efficient and sustainable syngas fermentation processes.

Transcriptional response of Methanosarcina acetivorans to repression of the energy-conserving methanophenazine: CoM-CoB heterodisulfide reductase enzyme HdrED.

Methane-producing archaea are key organisms in the anaerobic carbon cycle. These organisms, also called methanogens, grow by converting substrate to methane gas in a process called methanogenesis. Previous research showed that the reduction of the terminal electron acceptor is the rate-limiting step in methanogenesis by Methanosarcina acetivorans. In order to gain insight into how the cells sense and respond to the availability of the terminal electron acceptor, we designed an experiment to deplete cells of the essential terminal oxidase enzyme, HdrED. We found that the depletion of HdrED in vivo results in a higher abundance of transcripts for methyltransferases (mtaC2, mtaB3, mtaC3), coenzyme B biosynthesis, C1 metabolism, and pyrimidine compounds. In most cases, these changes were distinct from transcript abundance changes observed during the transition from exponential growth to stationary phase cultures. These data implicate the methylotrophic methanogenesis regulator MsrC (MA4383) in CoM-S-S-CoB heterodisulfide sensing and indicate cells have a specific mechanism to sense intracellular ratio of CoM-S-S-CoB, coenzyme M, and coenzyme B thiols and further suggest transcripts encoding translation and methanogenesis functions are controlled by feed-forward regulation depending on substrate availability.IMPORTANCEMethanosarcina is an emerging model archaeon and synthetic biology platform for the production of renewable energy and sustainable chemicals to reduce dependence on petroleum. Research into metabolic networks and gene regulation in this organism and other methanogens will inform genome-scale metabolic modeling and microbial function prediction in uncultured or non-model anaerobes and archaea. This study suggests methanogens use unknown mechanisms to efficiently couple methanogenesis to gene regulation via CoM-S-S-CoB and ATP availability.

Pd EnCat™ 30 Recycling in Suzuki Cross-Coupling Reactions

Pd EnCat™ 30 is a palladium catalyst broadly used in several hydrogenation and cross-coupling reactions. It is known for its numerous beneficial features, which include high-yielding performance, easy recovery, and reusability. However, the available data regarding its recyclability in Suzuki coupling reactions are limited to a few reaction cycles and, therefore, fail to explore its full potential. Our work focuses on investigating the extent of Pd EnCat™ 30 reusability in Suzuki cross-coupling reactions by measuring its performance according to isolated yields of product. Our findings demonstrate that Pd EnCat™ 30 can be reused over a minimum of 30 reaction cycles, which is advantageous in terms of cost reduction and more sustainable chemical production.

Optimizing macroalgal biochar-based catalysts for monophenols recovery during wood dust catalytic pyrolysis: A comparative study using response surface methodology and artificial neural network

This study aimed to explore the optimization of macroalgal biochar-based catalysts (MBBCs) for enhanced monophenolic production in biomass pyrolysis. By utilizing response surface methodology (RSM) and artificial neural network (ANN), key variables in the activation process during preparation of MBBCs were identified including activation temperature, activator ratio, and CO2 residence time. The results showed that the ANN model, with an R2 of 0.9816, accurately predicted optimal catalyst activation conditions, closely matching the experimentally determined optimal conditions (ENPC800-1:2–30). The bio-oil yield decreased under ENPC800-1:2–30 catalyst, but the monophenolic content increased significantly, reaching a relative content of 60 %, with a total concentration of phenol, cresols, and ethylphenol amounting to 35.54 mg/gbio-oil. The present study revealed significant changes in non-condensable gas composition, including increased hydrogen and carbon monoxide which aid in enhancing their energy applications. Thus, the optimized MBBCs greatly help in improving the bio-oil and non-condensable gas quality and thereby providing vital insights over sustainable chemical production through biomass pyrolysis.

Universal high-efficiency electrocatalytic olefin epoxidation via a surface-confined radical promotion

Production of epoxides via selective oxidation of olefins affords a fundamental source of key intermediates for the industrial manufacture of diverse chemical stocks and materials. Current oxidation strategy generally works under harsh conditions including high temperature, high pressure, and/or request for potentially hazardous oxidants, leading to substantial challenges in sustainability and energy efficiency. To this end, direct electrocatalytic epoxidation poses as a promising solution to these issues, yet their industrial applications are limited by the low selectivity, low yield, and poor stability of the electrocatalysts. Here we report a universal electrochemical epoxidation approach via a kinetically confined surface radical pathway. High epoxidation efficiency can be achieved under mild working conditions (e.g., >99% selectivity, >80% yield and >80% Faraday efficiency for cyclohexene-to-cyclohexene oxide conversion), which can be extended to broad scope of olefin substrates. The catalytic performance originated from a surface bimolecular (L-H) reaction mechanism involving formation and surface confinement of bromine radicals due to kinetic restriction, which effectively activates inert C=C bonds while avoiding the homogenous radical side reactions. With the use of renewable energy and water as green oxygen source, successful implementation of this approach will pave the way for more sustainable chemical production and manufacturing.

In Situ Electrochemical Conversion of Biomass-Derived 5-Hydroxymethylfurfural into 2,5-Furandicarboxylic Acid by Time-Controlled Aerosol-Assisted Chemical Vapor Deposited FeNi Catalyst.

The conversion of 5-hydroxymethylfurfural (HMF) into valuable chemicals, such as 2,5-furandicarboxylic acid (FDCA), is pivotal for sustainable chemical production, offering a renewable pathway to biodegradable plastics and high-value organic compounds. This pioneering study explores the synthesis of FeNi nanostructures via aerosol-assisted chemical vapor deposition (AACVD) for the electrochemical oxidation of HMF to FDCA. By adjusting the deposition time, we developed two distinct nanostructures: FeNi-40, which features nanowires with spherical terminations, and FeNi-80, which features aggregated spherical structures. X-ray diffraction (XRD) confirmed that both nanostructures possess a phase-pure face-centered cubic (FCC) crystal structure. Electrochemical tests conducted using FeNi nanocatalysts on Ni foam revealed that FeNi-40 requires a significantly lower onset potential for HMF oxidation (1.32 V vs RHE) compared to FeNi-80 (1.40 V vs RHE). This difference is attributed to the unique nanowire morphology of FeNi-40, which provides a higher density of active sites and a larger electrochemically active surface area, thereby enhancing the efficiency of the electrochemical process. When tested in an H-type electrolyzer with a Nafion membrane, FeNi-40 demonstrated a remarkable Faradaic efficiency of 96.42% and a high product yield, underscoring the potential of morphology-controlled FeNi nanostructures to enhance the efficiency of sustainable electrochemical processes significantly.

Magnetic Nanoparticles and Radio Frequency Induction: From Specific Heating to Magnetically Induced Catalysis

AbstractThis 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.

Cobalt-Catalyzed Divergence in C(sp3)-H Functionalization of 9H-Fluorene: A Streamlined Approach Utilizing Alcohols.

Sustainable chemical production demands the creation of innovative catalysts and catalytic technologies. While the development of coherent and robust catalytic systems using earth-abundant transition metals is essential, it remains a significant challenge. Herein, an expedient divergence strategy for tandem dehydrogenative C(sp3)-H alkylation and cyclization reactions of 9H-fluorene using a newly developed N,N-bidentate cobalt catalytic system is developed. This method capitalizes on the use of abundant and readily accessible alcohol. Demonstrating wide-ranging applicability, the catalytic protocol successfully integrated a diverse array of fluorenes and alcohols. This includes benzylic, heteroaromatic, and aliphatic primary and secondary alcohols, amassing a total of 75 distinct examples. When applied to sterically bulky alcohols, the reaction preferentially undergoes alkenylation, yielding a tetrasubstituted olefin as the main product. In the case of diols, the expected outcome is Dual-fluorescence at both terminal positions. This process leads to difluorination, followed by a cyclization step, culminating in the formation of a relatively unprecedented spiro compound. The scalability of this method has been validated through gram-scale synthesis. Control experiments have shed light on the reaction mechanism, indicating that it progresses through an unsaturated intermediate and adheres to the borrowing hydrogen pathway.

An Overview of Different Water Electrolyzer Types for Hydrogen Production

While fossil fuels continue to be used and to increase air pollution across the world, hydrogen gas has been proposed as an alternative energy source and a carrier for the future by scientists. Water electrolysis is a renewable and sustainable chemical energy production method among other hydrogen production methods. Hydrogen production via water electrolysis is a popular and expensive method that meets the high energy requirements of most industrial electrolyzers. Scientists are investigating how to reduce the price of water electrolytes with different methods and materials. The electrolysis structure, equations and thermodynamics are first explored in this paper. Water electrolysis systems are mainly classified as high- and low-temperature electrolysis systems. Alkaline, PEM-type and solid oxide electrolyzers are well known today. These electrolyzer materials for electrode types, electrolyte solutions and membrane systems are investigated in this research. This research aims to shed light on the water electrolysis process and materials developments.