Production Of Chemicals Research Articles

Reactive Passivation of Wide-Bandgap Organic-Inorganic Perovskites with Benzylamine.

While amines are widely used as additives in metal-halide perovskites, our understanding of the way amines in perovskite precursor solutions impact the resultant perovskite film is still limited. In this paper, we explore the multiple effects of benzylamine (BnAm), also referred to as phenylmethylamine, used to passivate both FA0.75Cs0.25Pb(I0.8Br0.2)3 and FA0.8Cs0.2PbI3 perovskite compositions. We show that, unlike benzylammonium (BnA+) halide salts, BnAm reacts rapidly with the formamidinium (FA+) cation, forming new chemical products in solution and these products passivate the perovskite crystal domains when processed into a thin film. In addition, when BnAm is used as a bulk additive, the average perovskite solar cell maximum power point tracked efficiency (for 30 s) increased to 19.3% compared to the control devices 16.8% for a 1.68 eV perovskite. Under combined full spectrum simulated sunlight and 65 °C temperature, the devices maintained a better T80 stability of close to 2500 h while the control devices have T80 stabilities of <100 h. We obtained similar results when presynthesizing the product BnFAI and adding it directly into the perovskite precursor solution. These findings highlight the mechanistic differences between amine and ammonium salt passivation, enabling the rational design of molecular strategies to improve the material quality and device performance of metal-halide perovskites.

Molecular Engineering of Poly(Ionic Liquid) for Direct and Continuous Production of Pure Formic Acid from Flue Gas.

Electrochemical CO2 reduction reaction (CO2RR) offers a promising approach to close the carbon cycle and reduce reliance on fossil fuels. However, traditional decoupled CO2RR processes involve energy-intensive CO2 capture, conversion, and product separation, which increases operational costs. Here, we report the development of a bismuth-poly(ionic liquid) (Bi-PIL) hybrid catalyst that exhibits exceptional electrocatalytic performance for CO2 conversion to formate. The Bi-PIL catalyst achieves over 90% Faradaic efficiency for formate over a wide potential range, even at low 15% v/v CO2 concentrations typical of industrial flue gas. The biphenyl in PIL backbone affords hydrophobicity while maintaining high ionic conductivity, effectively mitigating the flooding issues. The PIL layer plays a crucial role as a CO2 concentrator and co-catalyst that accelerates the CO2RR kinetics. Furthermore, we demonstrate the potential of Bi-PIL catalysts in a solid-state electrolyte (SSE) electrolyzer for the continuous and direct production of pure formic acid solutions from flue gas. Techno-economic analysis suggests that this integrated process can produce formic acid at a significantly reduced cost compared to the traditional decoupled approaches. This work presents a promising strategy to overcome the challenges associated with low-concentration CO2 utilization and streamline the production of valuable liquid fuels and chemicals from CO2.

A Multi-Method Approach to Assess the Adoption of Precision Agriculture Technology in Brazil

Precision Agriculture (PA) application aims to increase crop productivity while minimizing environmental impacts. We analyzed the topics most studied in the advancement of crop production in Brazil by applying the concepts of PA using the systematic literature review (SLR). A multi-method approach combined an SLR applying the PRISMA method and secondary data analysis. We found five clusters of technologies using the PA concept related to hardware development and four clusters related to applying technologies to software development in the PA concept. Most topics focused on using sensors to control water (soil and environment), soil electrical conductivity, and data communication. The focus on sustainability led researchers to reduce chemical products related to fertilizers and pesticides using Variable Rate Fertilizers (VRT) and reducing the environmental loading. According to the research results, it was evident that PA technology might help farmers make more accurate decisions about cultivation, production, harvest, and soil management. The availability of decision support systems powered by big data and artificial intelligence to select the best crop for a given season and soil might assist Brazil's sustainable growth of food production.

Composting as a Cleaner Production Strategy for the Soil Resource of Potato Crops in Choconta, Colombia

Choconta is the municipality in Colombia with the greatest prevalence of potato planting, representing 70.90% of the total territory. However, this crop has been affected by the presence of pests, diseases, and chemical contaminants from pesticides and chemical fertilizers that deteriorate the soil and, therefore, the quality of the final product. Compost (organic waste with specific characteristics and made from waste generated in Choconta) was studied as a sustainable production strategy to increase soil quality and thereby the quality of the local potato crop. For this purpose, a 3 × 2 experiment design was implemented with three treatments (0%, 25%, and 50% compost) and two variables (young potato and mature potato) in duplicate for 4 months. In this experiment, the use of compost led to an improved final product, which went from a floury texture to a dense and creamy texture. The use of compost also reduced the levels of heavy metals, such as lead, with a higher removal in treatment 3 (50% composting). The estimated direct cost of the composting process was USD 280.85, slightly lower than that of the application of fertilizers at USD 294.48. The use of fertilizers has a higher environmental impact due to the use of chemical products that have environmental and health implications. Using compost did not influence tuber harvest time but had a positive impact on tuber texture quality and on soil resources through the reduction in heavy metals, especially lead (16.40–18.03 ppm for treatment 1, 17.96–18.49 ppm for treatment 2, and 15.67–17.88 ppm for treatment 3). Using compost could be environmentally and economically beneficial for local farmers, and it promotes the circular economy and sustainable communities.

Two branches solutions for mixed convection flow of thermally Williamson nanofluid flow with heat transfer due to magnetized shrinking sheet

AbstractThe study of magnetohydrodynamics (MHD) and thermal radiation over‐stretching and shrinking sheets has significant applications in a wide range of fields, from chemical manufacturing to transport engine cooling systems, electronic chip cooling, plasma, the nuclear‐powered sector, saltwater, etc. The present study aims to numerically and theoretically analyze the movement of thermally magnetized Williamson nanofluid owing to an extended/contracting sheet. The regulating flow equations are converted to self‐similar equations through similarity transformation, and then numerically solved by bvp4c using MATLAB software. A comparison of the present numerical study with the published study is quite impressive. The investigation demonstrates that the self‐similar equations disclose the two branches for the limited shrinking factor range. For the stretching case, only one solution exists. As a result, the most fundamentally feasible solution has been determined by the linear assessment of temporal stability. For the aim of stability analysis, the lowest eigenvalue sign indicates the stability or instability of a solution. Through stability analysis, it is witnessed that the first solution (first branch) is stable. Due to the presence of the Lorentz force effect, it is perceived that the velocity curves decline in the whole channel. The point to be noted here is that the velocity of the lower branch compared to the upper branch is higher. The reduced Skin Friction is increased in the first branch and declines in the second branch for the two different values of magnetic factor.

Soybean biorefinery and technological forecasts based on a bibliometric analysis and network mapping

Global warming and increasing pollution have become critical global issues, and, coupled depletion of traditional energy sources, have accelerated the adoption of more sustainable production systems, such as biorefineries. Biorefineries possess the capacity to integrate technologies and processes within a single facility, thereby generating biofuels, high-value-added chemical products, and energy. The current study aims to evaluate various scenarios of soybean biorefineries by employing a bibliometric analysis and network mapping to facilitate and implement technological forecasting. To achieve this objective, eight methodological steps were undertaken. The majority of studies reviewed were primarily concerned with the utilization of soybean straw and hulls, motivated by the need to address environmental challenges related to the disposal of substantial volumes of these residues. Research on the application of soy whey also emerged as significant, mainly due to its connection with soy protein isolates. The seven most promising technological avenues identified were nanocomposites, peroxidases, ethanol, green composites, biochar, films, and biodiesel. Consequently, the findings provide a bibliographic foundation for future research on the integration of soybean-derived residues, processes, and products, which could foster innovation within the biorefinery framework and lead to crucial advancements in the processes.

Numerical Simulation and Response Surface Analysis of Esterification of Monobutyl Chlorophosphate with n-Butanol in a Microchannel Reactor

Microreactors are essential for microchemical reactions owing to their high mass transfer efficiency, precise control of reaction time, easy amplification, and good safety performance. These characteristics provide several advantages, including shortened reaction times and enhanced chemical reaction conversion rates, rendering microreactors particularly significant in chemical production. In this study, a finite-rate model was developed for the esterification of monobutyl chlorophosphate (MCP) and n-butanol in a microchannel reactor. This study investigates the impact of the microchannel’s length-to-diameter ratio, the mass ratio of n-butanol to MCP at the inlet, and the inlet flow ratio on the entire reaction system through numerical simulations. The findings indicate that increasing the length-to-diameter ratio and reducing the inlet flow rate effectively prolongs the residence time of materials in the microreactor, thereby enhancing the conversion rate of the reactants. Optimal results are achieved with a moderate n-butanol/MCP mass ratio, which facilitates MCP transformation. Moreover, this study employs response surface analysis to investigate the influence of independent factors, such as the microchannel’s length-to-diameter ratio, component ratio, and inlet velocity ratio, on MCP conversion rates. A prediction formula with conversion rate as the dependent variable and microchannel length-to-diameter ratio, component ratio, and inlet velocity ratio as independent variables was established.

Combinatorial optimization of the hybrid cellulase complex structure designed from modular libraries.

Cellulase selectively recognizes cellulose surfaces and cleaves their β-1,4-glycosidic bonds. Combining hydrolysis using cellulase and fermentation can produce alternative fuels and chemical products. However, anaerobic bacteria produce only low levels of highly active cellulase complexes so-called cellulosomes. Therefore, we designed hybrid cellulase complexes from 49 biotinylated catalytic domain (CD) and 30 biotinylated cellulose-binding domain (CBD) libraries on streptavidin-conjugated nanoparticles to enhance cellulose hydrolysis by mimicking the cellulosome structure. The hybrid cellulase complex, incorporating both native CD and CBD, significantly improved reducing sugar production from cellulose compared to free native modular enzymes. The optimal CBD for each hybrid cellulase complex differed from that of the native enzyme. The most effective hybrid cellulase complex was observed with the combination of CD6-4 from Thermobifida fusca YX and CBD46 from the Bacillus halodurans C-125. The hybrid cellulase complex/CD6-4-CBD46 and -CD6-4-CBD2-5 combinations showed increased reducing sugar production. Similar results were also observed in microcrystalline cellulose degradation. Furthermore, clustering on nanoparticles enhanced enzyme thermostability. Our results demonstrate that hybrid cellulase complex structures improve enzyme function through synergistic effects and extend the lifespan of the enzyme.

Hierarchical Ag3VO4 Nanorods as an Excellent Visible Light Photocatalyst for CO2 Conversion to Solar Fuels

The potential of photocatalytic CO2 conversion is significant for the production of fuels and chemicals, while simultaneously mitigating CO2 emissions and addressing environmental concerns. Despite the current drawbacks of single metal-based photocatalysts, such as lower performance, uncontrollable selectivity, and instability, this study focuses on the synthesis of Ag3VO4 nanorods using the sol–gel method. The goal is to create a highly effective catalyst for visible light-responsive CO2 conversion. The successful synthesis of Ag3VO4 nanorods with a nanorod structure, functional under visible light, resulted in the highest yields of CH4 and dimethyl ether (DME) at 271 and 69 µmole/g-cat, respectively. The optimized Ag3VO4 nanorods demonstrated performance improvements, with CH4 and DME production 6.4 times and 4.5 times higher than when using V2O5 samples. This suggests that Ag3VO4 nanorods facilitate electron transfer to CO2, offer short pathways for electron transfer, and create empty spaces within the nanorods as electron reservoirs, enhancing the photoactivity. The prolonged stability of Ag3VO4 in the CO2 conversion system confirms that the nanorod structure provides controllable selectivity and stability. Therefore, the fabrication of nanorod structures holds promise in advancing high-performance photocatalysts in the field of photocatalytic CO2 conversion to solar fuels.

Source apportionment of Volatile Organic Compounds (VOCs) in the South Coast Air Basin (SoCAB) During RECAP-CA

Ozone (O3) concentrations in the South Coast Air Basin (SoCAB) surrounding Los Angeles remain at unhealthy levels despite multiple decades of control programs designed to reduce emissions of precursor Volatile Organic Compounds (VOCs). Here we report on comprehensive VOC measurements made at Redlands, which has the highest measured O3 concentrations in SoCAB, as part of the Re-Evaluating the Chemistry of Air Pollutants in California (RECAP-CA) field campaign (July–October 2021). Positive matrix factorization (PMF) analysis was applied to identify nine VOC factors. A photochemical chamber model initialized by field measurements was configured with a tagging technique to quantify the VOC factor contributions to O3 formation in Redlands. Biogenic VOCs (BVOCs) made the largest contribution (26.6%) to O3 formation, followed by traffic VOCs (21.2%), volatile chemical products (VCPs) (19%), and plant decomposition (14.9%). High O3 episodes were not driven by increased VOC emissions from any single source, but rather were associated with stagnation events that concentrated VOCs from all sources and high temperature days that enhanced O3 formation efficiency. This implies that VOC controls optimized to reduce O3 concentrations would look similar in both the NOx-limited and VOC-limited regimes that can occur at Redlands. These results suggest that control strategies that reduce VOC and NOx emissions from the on-road vehicle fleet, such as increasing electrification, may yield O3 reductions on days in both the NOx-limited and VOC-limited chemical regimes at Redlands.

Integrated batch production planning and scheduling with machine-learning based production capacity region considering wind energy system

Continued greenhouse gas emission has led to increased global warming. Towards the goal of carbon emissions reduction and environmental sustainability, replacing high-polluting fossil fuel by clean energy has become a top priority in the decision-making of the current chemical industry. This work presents an optimization framework to address the integration of batch chemical production planning and scheduling considering energy consumption, which is a vital operational problem in chemical production. Assisting the linkage between planning layer and scheduling layer, a novel linear support vector machine based production capacity region calculation method is proposed to identify feasible regions of the scheduling layer. Uncertain factors in both the production system and the energy system are considered, including demand volatility of chemical products, energy supply fluctuations and time-varying energy market prices. To evaluate each strategy and the proposed model, simulation experiments are performed in three representative case studies. The results reveal that the integrated model considering energy consumption shows superior performance in different energy configurations, with or without wind energy generation and battery storage systems.

Reaction kinetics of Ni-Fe oxygen carriers with high performance for chemical looping hydrogen production

The chemical looping hydrogen production (CLHP) process utilizing iron-based oxygen carriers holds promise for practical hydrogen generation applications. However, challenges persist in developing iron-based carriers that are easy to prepare and demonstrate effective reactivity. Our research focuses on evaluating the CLHP reaction performance using bimetallic Ni-Fe oxygen carrier particles, synthesized by a scalable mechanical mixing method. This study unravels the role of Ni in bimetallic Ni-Fe oxygen carriers and investigates the influence of varying nickel-doping ratios on enhancing the reduction reactivity of iron-based oxygen carriers. Compared to the undoped sample, the 20 wt% nickel-doped Fe2O3/Al2O3 (20NiFe) particles enabled a reduction in the reaction temperature by at least 50 K. With the dopant, the methane conversion rate at 923 K is 500% higher than that of carriers without the dopant. Heterogeneous kinetic analysis demonstrates that the global reduction reaction data for the Ni-Fe oxygen carriers fit with the nucleation-nuclei growth model. Through redox reactivity tests and reduction kinetic analysis, 20NiFe shows the lowest apparent activation energy at 53.93 kJ/mol. Furthermore, the kinetic study and quasi in-situ XRD analysis aid in proposing the evolution process of methane reduction reaction for nickel-doped iron-based oxygen carriers, clarifying the role of doping in improving chemical looping reactivity from a kinetic perspective. This work provides valuable guidance for the design and optimization of oxygen carriers, thus accelerating the readiness for industrial deployment of hydrogen production via chemical looping process.

Roles of network topology in the relaxation dynamics of simple chemical reaction network models

Understanding the relationship between the structure of chemical reaction networks and their reaction dynamics is essential for unveiling the design principles of living organisms. However, while some network-structural features are known to relate to the steady-state characteristics of chemical reaction networks, mathematical frameworks describing the links between out-of-steady-state dynamics and network structure are still underdeveloped. Here, we characterize the out-of-steady-state behavior of a class of artificial chemical reaction networks consisting of the ligation and splitting reactions of polymers. Within this class, we examine minimal networks that can convert a given set of sources (e.g., nutrients) to a specified set of targets (e.g., biomass precursors). By exploring the dynamics of the models with a simple setup, we find three distinct types of relaxation dynamics after perturbation from a steady-state: exponential-, power-law-, and plateau-dominated. We computationally show that we can predict this out-of-steady-state dynamical behavior from just three features computed from the network’s stoichiometric matrix, namely, (1) the rank gap, determining the existence of a steady-state; (2) the left null-space, being related to conserved quantities in the dynamics; and (3) the stoichiometric cone, dictating the range of achievable chemical concentrations. We further demonstrate that these three quantities relates to the type of relaxation dynamics of combinations of our minimal networks, larger networks with many redundant pathways, and a real example of a metabolic network. The relationship between the topological features of reaction networks and the relaxation dynamics presented here are useful clues for understanding the design of metabolic reaction networks as well as industrially useful chemical production pathways.

Unspecific peroxygenase enabled formation of azoxy compounds

Enzymes are making a significant impact on chemical synthesis. However, the range of chemical products achievable through biocatalysis is still limited compared to the vast array of products possible with organic synthesis. For instance, azoxy products have rarely been synthesized using enzyme catalysts. In this study, we discovered that fungal unspecific peroxygenases are promising catalysts for synthesizing azoxy products from simple aniline starting materials. The catalytic features (up to 48,450 turnovers and a turnover frequency of 6.7 s–1) and substrate transformations (up to 99% conversion with 98% chemoselectivity) highlight the synthetic potential. We propose a mechanism where peroxygenase-derived hydroxylamine and nitroso compounds spontaneously (non-enzymatically) form the desired azoxy products. This work expands the reactivity repertoire of biocatalytic transformations in the underexplored field of azoxy compound formation reactions.

Constructing Highly Efficient Catalysts for the 1‐Butene Epoxidation

AbstractEpoxides are high‐valued intermediates in the production of chemicals, pharmaceuticals, perfumes, and polymers. Given the growing demand for epoxides, it is imperative to develop more environmental friendly and sustainable routes instead of the chlorohydrin process. Notably, the direct utilization of hydrogen peroxide (H2O2) for the epoxidation reaction presents significant advantages from both environmental and economic perspectives. The review provides insights into both homogeneous and heterogeneous catalysts employed in the 1‐butene epoxidation using the green oxidant H2O2. Among the diverse range of catalysts, titanosilicate‐1 (TS‐1) has garnered extensive attention due to its exceptional selectivity and high oxygen atom utilization. The aim of this review is to illustrate various strategies for TS‐1 catalysts preparation that can lead to more versatile, higher‐performance, and greener epoxidation processes. Additionally, various potential approaches to enhance the catalyst performance of TS‐1 are highlighted, including (i) constructing specific coordination modes of Ti sites, (ii) regulating the microenvironment around Ti sites, and (iii) improving the accessibility of Ti sites. Furthermore, advances in molding TS‐1 catalysts are also introduced from the perspective of the industrialization. Finally, future research directions are discussed with emphasis on the application scope of TS‐1 to gain deeper insights into epoxidation process.

Labor share decline across US manufacturing sectors: 1979–2019

ABSTRACT This paper studies the sectoral contributions to aggregate manufacturing labour share decline in the US between 1979 and 2019. Using the Log Mean Divisia index (LMDI) decomposition, the decline in the manufacturing sector’s labour share is decomposed into contributions from real wage growth, labour productivity growth, changes in employment shares, and relative prices arising from the constituent sectors across three business cycles. The primary findings of the paper suggest that the downward decoupling of real wages from labour productivity is the primary contributor to the labour share decline in manufacturing. Moreover, low labour share sectors (especially chemical products, food and beverage and tobacco products, and petroleum and coal products) have experienced an increase in their employment shares, contributing negatively to aggregate manufacturing labour share. This paper advances insights related to sectoral heterogeneity and possible mechanisms behind the decline in aggregate manufacturing labour share.

Fibrous catalyst based on atomic Pd and N-doped holey graphene functionalized cotton fiber for continuous-flow reaction

Continuous-flow catalysis bridges the gap between bench-scale laboratories and production-scale factories and thus should be a green and promising technology for the manufacture of value-added chemicals. Here, we present the construction of a continuous-flow catalytic system by integrating a tubular reactor with novel catalytic fibers, which are comprised of single-atomic Pd (Pd1) and nitrogen-doped holey graphene (NHG) functionalized cotton fibers (CFs). Due to the loosely packed structure, highly exposed dual-active sites (i.e., single-atomic PdN4 sites and activated C sites in the NHG carbocatalyst) of the CF@(Pd1/NHG) catalytic fibers, the corresponding flowing system exhibites remarkably high catalytic performance (activity and durability) and processing rate in organic reactions, including oxidative hydroxylation of phenylboronic acid and reduction of nitroarenes. Typically, the processing rate of the catalytic system toward 4-nitrophenol (a representative nitroarene) reduction can reach up to 2.46 × 10−3 mmol·mg−1·min−1, significantly higher than that of those packing catalysts reported in recent years.

In silico modelling of radiative efficiencies of anthropogenic greenhouse gases

Radiative efficiency (RE) is a climate metric adopted in international reports on climate change to quantify the greenhouse capacity of gases, and hence to guide decision-making processes and drive transitions in the production and utilization of chemicals in different application fields. Key quantities for the determination of the RE of a gas are the atmospheric irradiance profile and the infrared (IR) absorption cross section spectrum. The latter is usually measured experimentally, even though acquiring high-quality IR spectra can pose severe challenges, sometimes limiting the accuracy or the accessible spectral range. While computational quantum chemistry methods have emerged as valuable tools to simulate IR absorption properties, their application to REs estimation is still limited to the use of the double-harmonic approximation, which presents fundamental limitations. In this work, a cost-effective quantum chemical (QC) workflow including non-empirical anharmonic contributions to spectral properties and an automatic identification of conformer distribution is presented for the accurate evaluation of REs using a range of atmospheric irradiance profiles. Different levels of theory are considered, according to the current state-of-the-art, and the accuracy of the QC RE tool is demonstrated with reference to a number of representative halocarbons widely used in refrigeration, manufacturing, and pharmaceutical fields. The results show that REs can be computed with an average accuracy of 5% using double-hybrid functionals, which overshoot the widely used B3LYP method. Finally, the QC methodology is applied to determine the REs of selected halocarbons for which data is limited, or to address some contradictory results appeared in the literature for some species. The outcomes of this work demonstrate that QC anharmonic IR cross section spectra can be used to estimate REs with an accuracy on par with that of experimental measurements, hence applicable to challenging cases for providing data for policymakers as well for screening purposes when seeking new replacement compounds.

A CO2-emission free direct methanol fuel cell for simultaneous production of electrical energy and value-added chemicals

It remains challenges to efficiently convert carbon-based fuels such as methanol from CO2 into electrical energy while without CO2 greenhouse gas emission. Herein, a CO2-emission free direct methanol fuel cell (DMFC) has been realized through using unique Pt-CoOOH/nickel foam anode with high electro-catalytical selectivity, activity and stability. The DMFCs demonstrate simultaneous production of 18 mol of formate for every 1 kWh of electricity output with peak power density of 49.3 mW cm−2 and high selectivity of formate value-added chemicals up to 96 %. Moreover, this simple procedure does not consume energy while output electricity compared to the traditional formate production. It either does not use the toxic feedstock of CO and the reaction conditions are very mild. The in-situ Raman test indicates that CoOOH acts as an auxiliary active site to promote the conversion of *HCO to *HCOOH and improve the selectivity of formate. In-situ IR tests and density functional theory (DFT) calculations confirm that methanol tends to be oxidized selectively into formate rather than complete-oxidizing into CO2. This study achieves clean and efficient utilization of carbon-based fuels to co-generate electrical energy and value-added chemicals while no CO2 greenhouse emission, even realize the “negative carbon” cycle.

Electrified reformer for syngas production – Additive manufacturing of coated microchannel monolithic reactor

Here, an electrified reformer with a bespoke design of catalyst-coated and additively manufactured monoliths with 3-D pore architecture is presented. The 2D-pore architecture of the hexagonal honeycomb monolith was compared against the 3D-pore architecture of three broad classifications - triply periodic minimal surface (Gyroid), strut-based (Octet) and stochastic lattice (Voronoi). Gyroid structured reactor, coated with NiO/Ce0.8Gd0.2O2-δ catalyst and heated to 900 °C achieved >99 % conversion of CO2 and CH4 at WHSV = 11,000 L.h−1.kgcat−1, while remaining active for >42 h with no evidence of coke deposition. Whereas Octet and Voronoi reactors showed slightly lower conversions, with 6-fold and 4-fold higher pressure drops, respectively. This study combines Computational Fluid Dynamics and experimental evidence to reveal that the Gyroid lattice provides high catalyst deposition and catalytic activity at low pressure drops. This study demonstrates the feasibility of renewable energy-powered structured reactors to provide a pathway for low carbon footprint chemical production.