Routes For Production Of Chemicals Research Articles

Towards a Structured Framework for Techno‐Economic Analyses of Chemical Recycling Technologies

AbstractThe role of chemical recycling (CR) as a valuable complementary strategy to mechanical recycling in closing the carbon cycle for carbon‐containing waste is currently being discussed in political, economic, and social spheres. However, CR deployment is hindered by uncertainties regarding its environmental impacts and costs compared to conventional waste treatment and chemical production routes. While methods for assessing CR's environmental impacts are the focus of socio‐political debates and investigations, techno‐economic analyses (TEA) to evaluate costs of CR remain scarce. To contribute to a standardized framework for assessing the economic viability of CR technologies, this article draws on life cycle assessment and TEA literature to develop a six‐stage TEA process for CR. A checklist is also presented to support transparent and comprehensive analyses.

Metabolic Engineering of Bacillus subtilis for Riboflavin Production: A Review.

Riboflavin (vitamin B2) is one of the essential vitamins that the human body needs to maintain normal metabolism. Its biosynthesis has become one of the successful models for gradual replacement of traditional chemical production routes. B. subtilis is characterized by its short fermentation time and high yield, which shows a huge competitive advantage in microbial fermentation for production of riboflavin. This review summarized the advancements of regulation on riboflavin production as well as the synthesis of two precursors of ribulose-5-phosphate riboflavin (Ru5P) and guanosine 5'-triphosphate (GTP) in B. subtilis. The different strategies to improve production of riboflavin by metabolic engineering were also reviewed.

Synthesis of Phthalimide Imine Derivatives as a Potential Anticancer Agent

The outstanding evidence of phthalimide pharmacophore in securing enhanced biological activities had encouraged further research and development into phthalimide-based derivatives as potential new drugs. In this study, phthalimide core was hybridized with aldehydes giving integrated imines displaying different types of functionalities and at alternating positions. The resulting compounds, therefore, provide an innovative window to explore possible differential biological effects as antioxidants and anticancer agents. A total of sixteen compounds were synthesized, and each was verified by FT-IR, H NMR, C NMR, and MS characterization. Herein, a facile single-step synthesis method was employed substituting the conventional two-step chemical production routes. Among the sixteen tested compounds, the H7 compound with hydroxyl phenolic group has shown an eminent antioxidant activity with a 19.52% decrease to the IC50 value compared to that of the control standard BHT antioxidant. On the other hand, the halogenated H6 Schiff base structure was successful in securing effective cancer inhibition to both colon and breast cancer cell lines, while maintaining selective action toward normal tissues. Results have collectively indicated the importance and impactful effects of functional groups position and types within similar basic structures, in directing different biological outcomes.

Fifteen Years of Supported Ionic Liquid Phase-Catalyzed Hydroformylation: Material and Process Developments

This review describes the development of supported ionic liquid phase (SILP) materials as novel hydroformylation catalysts. Ligand-modified rhodium catalysts can be immobilized in a thin film of ionic liquid, which itself is dispersed on a porous material. The solid SILP catalysts have been improved with respect to activity, selectivity, and stability. In addition, their applicability in continuous gas-phase processes opens new opportunities for improved chemical production routes.

Theoretical Insights into the Mechanism and Stereoselectivity of Olefin Cyclopropanation Catalyzed by Two Engineered Cytochrome P450 Enzymes.

Engineered P450s can catalyze some non-natural reactions with high efficiency and excellent selectivity, such as the carbine transfer, nitrene transfer, C-H insertion, and C-H amination, opening alternative routes for sustainable production of chemicals. Recent experiments revealed that two engineered cytochrome P450 enzymes (P450BM3-CIS and P411BM3-CIS) show different efficiencies and stereoselectivities in the olefin cyclopropanation, but key factors that affect the activity remain unclear. In this work, both quantum mechanics (QM) and QM/molecular mechanics (MM) methods were employed to explore the catalytic reactions and selectivity of these two engineered cytochrome P450 enzymes. On the basis of our results, the cyclopropanation of styrene is suggested to mainly occur on the open-shell singlet (OSS) and triplet state surfaces, which contain two elementary steps. The reactive iron(III)-porphyrin carbene (IPC) radical first attacks the terminal alkenyl group of styrene to form a C-radical intermediate, which then undergoes a cyclization reaction affording the cyclopropanation products. Importantly, it is found that the stereoselectivity of cyclopropanations is elucidated only if considering the real protein environment, and the stereoselectivity is determined by multiple factors, such as the relative orientation of IPC to styrene, the binding affinity of the substrate, and the reaction barriers of rate-limiting steps. It is the enzymatic environment that makes the reaction highly stereoselective, which provides useful clues for designing whole-cell catalysts for non-natural chemical reactions.

Composite Photoelectrocatalysts for Tempo-mediated Alcohol Oxidations

The transformation of primary alcohols to higher valuable carbonyls or acids has attached enormous attention from both academic and industrial viewpoints, but typically requires stoichiometric oxidants, which are costly and generate potentially toxic waste. Previously, we have studied selective electrocatalytic oxidation of biomass-derived alcohols and 5-hydroxymethylfurfural (HMF) on noble metal catalysts.[1-3] Electroactive homogeneous catalysts such as (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) represent an alternative to expensive metal catalysts.[4] Conversion of biorenewable feedstock in a photoelectrochemical cell (PEC) [5] is potentially one of the most environmentally-friendly chemical production routes available, which takes advantage of renewable carbon sources from the earth, renewable photons from the sun, and renewable electrons from wind, geothermal, or photovoltaic sources. However, there is a need to develop new composite materials which can simultaneously facilitate light absorption, charge separation, charge transport, and electrochemical reactions. We have investigated the use of composite photoanodes for efficient TEMPO-mediated oxidations. Bismuth vanadate (BiVO4) semiconductor films modified with an earth-abundant cobalt phosphate (Co-Pi) layer facilitated TEMPO oxidation at overpotentials almost 500 mV lower than unmodified BiVO4, while simultaneously suppressing the undesired oxygen evolution reaction. The photoanode materials were characterized using XRD, XPS, SEM, EDS, UV/vis and photoelectrochemical measurements. The composite photoanodes achieved complete oxidation of HMF to 2,5-furandicarboxylic acid (FDCA) with 88% yield, whereas an unmodified BiVO4 only reached partial oxidation intermediates (FDCA yield <1%) under the same conditions. Transient photocurrents revealed the role of Co-Pi for promoted TEMPO oxidation is two-fold: (1) to efficiently remove photogenerated charges from the semiconductor and (2) promote charge transfer across the catalyst-electrolyte interface for TEMPO oxidations.

Perspective tendencies in development of small scale processing of gas resources

Abstract This paper analyses alternative routes for production of chemicals from different hydrocarbon gases by their direct, without syngas production, oxidative conversion to oxygenates or ethylene. Main of these routes are direct oxidation of methane to methanol (DMTM) and selective oxy-cracking of heavier natural or associated petroleum gas components which can be used for production of high value-added petrochemicals (in combination with carbonylation processes) and fuel gases, useful for gas piston engines. The advantages and practical capabilities of such technologies are discussed.

Rational engineering of diol dehydratase enables 1,4-butanediol biosynthesis from xylose

Establishing novel synthetic routes for microbial production of chemicals often requires overcoming pathway bottlenecks by tailoring enzymes to enhance bio-catalysis or even achieve non-native catalysis. Diol dehydratases have been extensively studied for their interactions with C2 and C3 diols. However, attempts on utilizing these insights to enable catalysis on non-native substrates with more than two hydroxyl groups have been plagued with low efficiencies. Here, we rationally engineered the Klebsiella oxytoca diol dehydratase to enable and enhance catalytic activity toward a non-native C4 triol, 1,2,4-butanetriol. We analyzed dehydratase's interaction with 1,2-propanediol and glycerol, which led us to develop rationally conceived hypotheses. An in silico approach was then developed to identify and screen candidate mutants with desired activity. This led to an engineered diol dehydratase with nearly 5 fold higher catalytic activity toward 1,2,4-butanetriol than the wild type as determined by in vitro assays. Based on this result, we then expanded the 1,2,4-butanetriol pathway to establish a novel 1,4-butanediol production platform. We engineered Escherichia coli's xylose catabolism to enhance the biosynthesis of 1,2,4-butanetriol from 224mg/L to 1506mg/L. By introducing the complete pathway in the engineered strain we achieve de novo biosynthesis of 1,4-butanediol at 209mg/L from xylose. This work expands the repertoire of substrates catalyzed by diol dehydratases and serves as an elucidation to establish novel biosynthetic pathways involving dehydratase based biocatalysis.

Mapping the patent landscape of synthetic biology for fine chemical production pathways.

SummaryA goal of synthetic biology bio‐foundries is to innovate through an iterative design/build/test/learn pipeline. In assessing the value of new chemical production routes, the intellectual property (IP) novelty of the pathway is important. Exploratory studies can be carried using knowledge of the patent/IP landscape for synthetic biology and metabolic engineering. In this paper, we perform an assessment of pathways as potential targets for chemical production across the full catalogue of reachable chemicals in the extended metabolic space of chassis organisms, as computed by the retrosynthesis‐based algorithm RetroPath. Our database for reactions processed by sequences in heterologous pathways was screened against the PatSeq database, a comprehensive collection of more than 150M sequences present in patent grants and applications. We also examine related patent families using Derwent Innovations. This large‐scale computational study provides useful insights into the IP landscape of synthetic biology for fine and specialty chemicals production.

Life cycle indicator comparison of copper, silver, zinc and aluminum nanoparticle production through electric arc evaporation or chemical reduction

Ways to produce metallic nanoparticles and the scale-up of these processes have seen increased interest as the industrial application of nanoparticles continues to grow. Their feasibility from an environmental point of view can be assessed by means of life cycle analysis (LCA). In this work two methods of metallic nanoparticle production, by evaporation/condensation of metal using electrical arc discharge reactors or by chemical reduction of metal salts in aqueous solutions or dry solid/solid mixtures, are evaluated based on the life cycle indicators. The evaporation of metal using electrical discharge reactors is a method studied in the European Commission 7th Framework Program “BUONAPART-E.” The environmental impact of the two different nanoparticle production approaches is here compared for four metals: copper, silver, zinc and aluminum. The chemical routes of producing nanoparticles require several different chemicals and reactions, while the electrical discharge routes use electricity to evaporate metal in a reactor under inert atmosphere. The nanoparticle production processes were modeled using “SimaPro” LCA software. Data for both the chemical production routes and the arc routes were taken from the literature. The choice of the best route for the production of each metal is strongly dependent on the final yield of the metallic nanoparticles. The yields for the chemical processes are not reported in the open literature, and therefore the comparisons have to be made with varying yields. At similar yields the electrical process has in general a lower environmental footprint than the studied chemical routes. The step or chemical with the greatest environmental impact varies significantly depending on process and metal being studied.

ChemInform Abstract: Rhenium‐Catalyzed Dehydration and Deoxydehydration of Alcohols and Polyols: Opportunities for the Formation of Olefins from Biomass

AbstractReview: 96 refs.

Rhenium-Catalyzed Dehydration and Deoxydehydration of Alcohols and Polyols: Opportunities for the Formation of Olefins from Biomass

In view of the depletion of petroleum oils, new synthetic routes for the sustainable production of chemicals, fuels, and energy from renewable biomass sources are currently widely investigated. In particular, nonedible sugars and polyols are promising starting materials to produce olefins by dehydration, deoxygenation, or deoxydehydration (DODH) of these poly vicinal alcohols. In this perspective, we highlight the recent evolution of rhenium-catalyzed dehydration and DODH of biomass-derived alcohols and polyols to obtain olefins. Improving over the classical acid-catalyzed dehydration reaction, rhenium-mediated systems are very selective and more active to provide high yields of olefin products, but dehydration alone cannot be used to fully defunctionalize sugars. This issue is addressed by a growing research effort in the field of Re-catalyzed DODH, which allows complete dehydroxylation to form olefins in high yield. Recent developments in this field include the development of new molecular rhenium catal...

An industrial view of process intensification

An integrated approach in chemical research and development, and chemical engineering is currently re-emerging under the label process intensification in academia as well as in industry. The promise of process intensification, as already expressed in the late 1970s, is to significantly increase the economic and ecological efficiency of chemical production routes. However, the rate of adoption in the chemical industry has been generally low and only a few examples have been reported since then. This paper addresses micro process technology, which is recognized as one important approach for process intensification in the chemical and process industry. It is particularly well suited for fast and extremely exothermic reactions enabling almost perfect process control. This feature could pave the way for considerable process improvements with regard to specific applications. A brief illustration of the advantages for gas-phase reactions is given. The incorporation of appropriately designed microstructured catalytic wall reactors within conventional partial oxidation production plants is presented.

Chemical fixation of CO 2 in carbonates: Routes to valuable products and long-term storage

Carbon dioxide emissions to the atmosphere can be reduced by chemical fixation in organic or inorganic carbonates. Many compounds can be commercially produced on an industrial scale using CO 2, allowing for turning a (nowadays problematic) waste gas into economic profit. Besides this, the carbonation of magnesium silicates and calcium silicates is an option for long-term storage of CO 2 at a capacity that exceeds that of other options for CO 2 storage by several orders of magnitude, with the inherent benefit that post-storage monitoring of the stored CO 2 is not necessary. The first part of this paper gives an overview of commercial carbonate chemical production routes that do (or in a near future can) make use of the CO 2 that is produced at a large scale from human activities. The second part addresses the process technology, market potential and other aspects of mineral carbonation for long-term CO 2 storage as an alternative for, for example, storage in underground aquifers.