Production Of Specialty Chemicals Research Articles

A Comprehensive Review of Fine Chemical Production Using Metal-Modified and Acidic Microporous and Mesoporous Catalytic Materials

Fine chemicals are produced in small annual volume batch processes (often <10,000 tonnes per year), with a high associated price (usually >USD 10/kg). As a result of their usage in the production of speciality chemicals, in areas including agrochemicals, fragrances, and pharmaceuticals, the need for them will remain high for the foreseeable future. This review article assesses current methods used to produce fine chemicals with heterogeneous catalysts, including both well-established and newer experimental methods. A wide range of methods, utilising microporous and mesoporous catalysts, has been explored, including their preparation and modification before use in industry. Their potential drawbacks and benefits have been analysed, with their feasibility compared to newer, recently emerging catalysts. The field of heterogeneous catalysis for fine chemical production is a dynamic and ever-changing area of research. This deeper insight into catalytic behaviour and material properties will produce more efficient, selective, and sustainable processes in the fine chemical industry. The findings from this article will provide an excellent foundation for further exploration and a critical review in the field of fine chemical production using micro- and mesoporous heterogeneous catalysts.

Biological Upcycling of Plastics Waste.

Plastic wastes accumulate in the environment, impacting wildlife and human health and representing a significant pool of inexpensive waste carbon that could form feedstock for the sustainable production of commodity chemicals, monomers, and specialty chemicals. Current mechanical recycling technologies are not economically attractive due to the lower-quality plastics that are produced in each iteration. Thus, the development of a plastics economy requires a solution that can deconstruct plastics and generate value from the deconstruction products. Biological systems can provide such value by allowing for the processing of mixed plastics waste streams via enzymatic specificity and using engineered metabolic pathways to produce upcycling targets. We focus on the use of biological systems for waste plastics deconstruction and upcycling. We highlight documented and predicted mechanisms through which plastics are biologically deconstructed and assimilated and provide examples of upcycled products from biological systems. Additionally, we detail current challenges in the field, including the discovery and development of microorganisms and enzymes for deconstructing non-polyethylene terephthalate plastics, the selection of appropriate target molecules to incentivize development of a plastic bioeconomy, and the selection of microbial chassis for the valorization of deconstruction products.

Biosynthesis of Strained Amino Acids by a PLP‐Dependent Enzyme through Cryptic Halogenation

Amino acids (AAs) are modular building blocks which nature uses to synthesize both macromolecules, such as proteins, and small molecule natural products, such as alkaloids and non‐ribosomal peptides. While the 20 main proteinogenic AAs display relatively limited side chain diversity, a wide range of non‐canonical amino acids (ncAAs) exist that are not used by the ribosome for protein synthesis, but contain a broad array of structural features and functional groups. In this communication, we report the discovery of the biosynthetic pathway for a new ncAA, pazamine, which contains a cyclopropane ring formed in two steps. In the first step, a chlorine is added onto the C4 position of lysine by a radical halogenase, PazA. The cyclopropane ring is then formed in the next step by a pyridoxal‐5’‐phosphate‐dependent enzyme, PazB, via an SN2‐like attack at C4 to eliminate chloride. Genetic studies of this pathway in the native host, Pseudomonas azotoformans, show that pazamine potentially inhibits ethylene biosynthesis in growing plants based on alterations in the root phenotype of Arabidopsis thaliana seedlings. We further show that PazB can be utilized to make an alternative cyclobutane‐containing AA. These discoveries may lead to advances in biocatalytic production of specialty chemicals and agricultural biotechnology.

Biosynthesis of Strained Amino Acids by a PLP-Dependent Enzyme through Cryptic Halogenation.

Amino acids (AAs) are modular building blocks which nature uses to synthesize both macromolecules, such as proteins, and small molecule natural products, such as alkaloids and non-ribosomal peptides. While the 20 main proteinogenic AAs display relatively limited side chain diversity, a wide range of non-canonical amino acids (ncAAs) exist that are not used by the ribosome for protein synthesis, but contain a broad array of structural features and functional groups. In this communication, we report the discovery of the biosynthetic pathway for a new ncAA, pazamine, which contains a cyclopropane ring formed in two steps. In the first step, a chlorine is added onto the C4 position of lysine by a radical halogenase, PazA. The cyclopropane ring is then formed in the next step by a pyridoxal-5'-phosphate-dependent enzyme, PazB, via an SN2-like attack at C4 to eliminate chloride. Genetic studies of this pathway in the native host, Pseudomonas azotoformans, show that pazamine potentially inhibits ethylene biosynthesis in growing plants based on alterations in the root phenotype of Arabidopsis thaliana seedlings. We further show that PazB can be utilized to make an alternative cyclobutane-containing AA. These discoveries may lead to advances in biocatalytic production of specialty chemicals and agricultural biotechnology.

OptMSP: A toolbox for designing optimal multi-stage (bio)processes

One central goal of bioprocess engineering is to maximize the production of specific chemicals using microbial cell factories. Many bioprocesses are one-stage (batch) processes (OSPs), in which growth and product synthesis are coupled. However, OSPs often exhibit low volumetric productivities due to the competition for substrate for biomass and product synthesis implying trade-offs between biomass and product yields. Two-stage or, more generally, multi-stage processes (MSPs) offer the potential to tackle this trade-off for improved efficiency of bioprocesses, for example, by separating growth and production. MSPs have recently gained much attention, also because of a rapidly growing toolbox for the dynamic control of metabolic fluxes. Despite these promising advancements, computational tools specifically tailored for the optimal design of MSPs in the field of biotechnology are still lacking.Here, we present OptMSP, a new Python-based toolbox for identifying optimal MSPs maximizing a user-defined process metrics (such as volumetric productivity, yield, and titer or combinations thereof) under given constraints. In contrast to other methods, our framework starts with a set of well-defined modules representing relevant stages or sub-processes. Experimentally determined parameters (such as growth rates, substrate uptake and product formation rates) are used to build suitable ODE models describing the dynamic behavior of each module. OptMSP finds then the optimal combination of those modules, which, together with the optimal switching time points, maximize a given objective function. We demonstrate the applicability and relevance of the approach with three different case studies, including the example of lactate production by E. coli in a batch setup, where an aerobic growth phase can be combined with anaerobic production phases with or without growth and with or without enhanced ATP turnover.

Tailored Fabrication of Plasmonic Film Light Filters for Enhanced Microalgal Growth and Biomass Composition.

Through plasmon resonance, silver and gold nanoparticles can selectively backscatter light within different regions of the visible electromagnetic spectrum. We engineered a plasmonic film technology that utilizes gold and silver nanoparticles to enhance light at the necessary wavelengths for microalgal photosynthetic activities. Nanoparticles were embedded in a polymeric matrix to fabricate millimeter-thin plasmonic films that can be used as light filters in microalgal photobioreactors. Experiments conducted with microalga Chlamydomonas reinhardtii proved that microalgal growth and photosynthetic pigment production can be increased by up to 50% and 78%, respectively, by using these plasmonic film light filters. This work provides a scalable strategy for the efficient production of specialty chemicals and biofuels from microalgae through irradiation control with plasmonic nanoparticles.

Design and engineering of artificial biosynthetic pathways-where do we stand and where do we go?

The production of commodity and specialty chemicals relies heavily on fossil fuels. The negative impact of this dependency on our environment and climate has spurred a rising demand for more sustainable methods to obtain such chemicals from renewable resources. Herein, biotransformations of these renewable resources facilitated by enzymes or (micro)organisms have gained significant attention, since they can occur under mild conditions and reduce waste. These biotransformations typically leverage natural metabolic processes, which limits the scope and production capacity of such processes. In this mini-review, we provide an overview of advancements made in the past 5 years to expand the repertoire of biotransformations in engineered microorganisms. This ranges from redesign of existing pathways driven by retrobiosynthesis and computational design to directed evolution of enzymes and de novo pathway design to unlock novel routes for the synthesis of desired chemicals. We highlight notable examples of pathway designs for the production of commodity and specialty chemicals, showcasing the potential of these approaches. Lastly, we provide an outlook on future pathway design approaches.

METHODOLOGICAL APPROACH TO THE ASSESSMENT OF FACTORS OF CHEMICAL PRODUCTION (ON THE EXAMPLE OF THE CARBON DIOXIDE MARKET)

Since the activity of industrial enterprises is influenced by many factors, it becomes necessary to assess this influence by methods of statistical analysis and economic and mathematical modeling. To take into account the many factors that affect the activities of chemical companies, it is advisable to use the methods of multiple correlation and regression analysis, which allows us to evaluate not only internal and external causeand-effect relationships, but also to study the development features and trends in the development of chemical companies and the resulting attribute. When constructing a correlation-regression model, the following requirements were met in the work: required number of factors that have a quantitative assessment for the analyzed market has a monthly distribution for January. 2019-Oct.2020; a sufficient amount of factor signs (the number of observations is almost 3 times higher than the number of factors); the totality of the studied factor characteristics is homogeneous. The purpose of this article is to develop a methodological approach to assessing the factors of production of chemical products. The article presents a step-by-step description of the algorithm, with the help of which it is proposed to evaluate the factors influencing the performance of chemical products. The following stages of the algorithm for assessing the factors of production of chemical products are identified: the formation of an information base for the study, the construction of a correlation matrix, the compilation of a predictive regression equation, the assessment of the statistical significance of the parameters of the obtained regression equation, and the development of proposals for achieving the predictive values of the resultant attribute. The research methodology proposed in the article makes it possible to identify factors in the development of specific chemical products, as well as to predict key indicators that affect the production of products. The practical significance of the study lies in the fact that the considered approach to forecasting the development of the market for chemical products makes it possible to determine the specific values of quantitative indicators that affect the volume of production of a particular type of chemical product. Approbation of the proposed approach was carried out on the example of the carbon dioxide (carbon dioxide) market. The results obtained confirm that the constructed model can be used to analyze and predict the main performance indicators of chemical companies.

Small-Scale Solids Production Plant with Cooling Crystallization, Washing, and Drying in a Modular, Continuous Plant

Small-scale continuous apparatuses for solid product manufacturing are receiving increasing interest due to the demand for the fast market availability of specialty chemical products manufactured in integrated and modular processing plants. Relevant unit operations span from crystallization over solid–liquid separation and filter cake washing to drying. For this purpose, the quasi-continuous filter belt crystallizer (QCFBC) was developed and is presented here. The newly integrated unit operations with positive pressure filtration (Δpmax = 0.8 bar), filter cake washing (V˙wash = 55 mL·min−1), and convection drying (Tdry = 60 °C) have been individually characterized and integrated into the filter apparatus that has been modified for continuous operation. They were synchronized with the flexible cooling crystallization, enabling for a seamless production process. Sucrose in water was used as model substance system. Long-term operations of up to 14 h were successfully performed with dry product filter cakes (22.64 g ± 1.64 g·h−1) of constant quality attributes (x50,3 = 216.095 ± 14.766, span = 0.347 ± 0.109, Yrel. = 69.9% ± 5%, XRM = 1.64 mg·g−1 ± 1.38 mg·g−1).

Valorization of biomass using deep eutectic solvent: a short review

The current rise in global energy demand has led to environmental concerns such as resource depletion and pollution. This has steered researchers towards exploring different renewable sources to achieve a sustainable circular bio-economy. Interestingly, the abundant nature of lignocellulose biomass (LCB) has attracted a lot of attention in the production of various specialty chemicals and fuels. The valorization of LCB requires that the recalcitrant structure of the biomass be broken down. However, the high capital cost, operating temperature, and several constraints that accompanythe pretreatment process make most of the pretreatment process economically unviable. Therefore, the quest for an environmentally benign pretreatment process led to the discovery of deep eutectic solvents (DES). They are classified as green solvents due to their biodegradable properties, lowcosts, eco-friendliness, enzyme compatibility, facile methods of synthesis, and recyclability. This review aims at giving information on LCB, Ionic liquids (ILs), and DES, the valorization of biomass to produce biofuel, and the recyclability of DES.

Quantifying the intrinsic value of algal biomass based on a multi-product biorefining strategy

Microalgal biomass is poised to become an important feedstock in the quest to decarbonize the fuels and chemical industries. In this way, it is imperative that researchers prioritize efforts for increased chances of economic viability of the microalgae biomass supply chain. This work applies a sequential techno-economic assessment (TEA) methodology to compare the economic trade-offs between microalgae growth and compositional shift while solving for an alternative economic metric: intrinsic algal biomass value, i.e., the revenue obtained from processing and converting the main components of algae biomass - carbohydrates, lipids, and protein - to a portfolio of products. The framework relies on data derived from small-scale cultivations to initially determine the maximum economic potential of different product portfolios as obtained in multiple biorefining setups. The approach further downselects the number of possible strains to undergo an in-depth TEA in order to quantify the value of transitioning from nutrient-replete to nutrient-deplete cultivations. Among the 13 permutations of strains and cultivation strategies analyzed, this study demonstrated an increase in intrinsic biomass value for four strains after the compositional shift: Chlorella sorokiniana DOE1412, Chlorella sorokiniana DOE1116, Scenedesmus obliquus UTEX393, and Scenedesmus obliquus DOE0152.Z. While product selection is critical in the exploitation of microalgal biomass, the four mentioned strains at least double their intrinsic biomass values, reaching up to $264/ton in net margins above minimum biomass selling prices. This is attainable without considering the production of small market size specialty chemicals, instead targeting markets with scalability potential and/or with currently large sizes. Two other strains, namely Picochlorum celeri WT-CSM/EMRE and Tetraselmis striata LANL1001, should have their biomass productivities increased by around 5 g/m2/day in nutrient-deplete cultivations to achieve economic viability. The concept of implementing an objective comparison between different portfolio configurations detailed herein is an innovative approach towards the economic assessment of microalgae valorization strategies.

Cover Feature: Continuous Flow Single‐Atom Catalysis: A Viable Organic Process Technology? (ChemCatChem 21/2022)

The Cover Feature shows a flow reactor employing a single-atom catalyst schematically represented. In their Perspective, M. Pagliaro, C. Della Pina and R. Ciriminna try to answer the question: “Is single-atom catalysis under continuous flow conditions a technically and economically viable organic process technology?” Early results actually suggest valuable insight en route to its industrial uptake in the production of fine and specialty chemicals. Reviewing selected examples of the first utilization of single-atom catalysts (SACs) under continuous-flow conditions, the authors provide evidence that SACs are not different from state-of-the-art supported metal nanoparticle catalysts in affording significantly higher TOFs than the same catalysts in batch reactor conversions. Furthermore, continuous flow conditions enhance the lot-to-lot consistency and dramatically lowers production time thug improving customer delivery. More information can be found in the Perspective by M. Pagliaro, C. Della Pina and R. Ciriminna.

Continuous Flow Single‐Atom Catalysis: A Viable Organic Process Technology?**

AbstractHeterogeneous catalysis under continuous flow conditions is increasingly used by the chemical industry to synthesize fine chemicals. Is single‐atom catalysis under flow a technically and economically viable organic process technology? Early results suggest valuable insight en route to the industrial uptake of single‐atom catalysis in the production of fine and specialty chemicals.

Extraction, quantification and characterization of lignin extracted from bamboo biomass

Lignin, a heterogeneous polymer that presents about 20–30% in lignocellulose emerged as a promising feedstock for the production of specialty chemicals. After cellulose, Lignin is the second most abundant natural polymer. Lignin is a three-dimensional, highly cross-linked macromolecule composed of three types of substituted phenols, which include coniferyl, sinapyl, and p-coumaryl alcohols having a vast number of functional groups and linkages. The properties of lignin are dependent upon the type of extraction method used. This work-study was carried out focusing on the properties of lignin extracted from bamboo (Bambusa Polymorpha) using acid treatment, alkali treatment and sequential organosolv treatment. Isolated lignins were characterized by Fourier transform infrared spectroscopy (FTIR), UV analysis, Thermogravimetric analysis (TGA) to compare thermal and chemical composition. It was found that lignin obtained from organosolv method provided the greatest yield of the various extraction methods. FTIR spectral studies showed the characteristics peaks of lignin and it was found that the bamboo lignin is unique and it is HGS type lignin. The type of extraction method used was seen to affect the thermal properties. It was found that lignin extracted from acid treatment has the greatest thermal stability and purity.

Compact NMR Spectroscopy in the Field: A Versatile PAT Tool for Production of Specialty Chemicals

Compact NMR Spectroscopy in the Field: A Versatile PAT Tool for Production of Specialty Chemicals

Characterizing Photosynthetic Biofuel Production: Isotopically Non-Stationary 13C Metabolic Flux Analysis on Limonene Producing Synechococcus sp. PCC 7002

Synechococcus sp. PCC 7002 is a unicellular cyanobacterium capable of fast growth and tolerance to high light intensity and high salinity. These attributes along with genetic tractability make Synechococcus sp. PCC 7002 an attractive candidate for industrial scale production of specialty and commodity chemicals. Synechococcus sp. PCC 7002 LS (Davies et al., Front Bioeng Biotechnol, 2014, 2, 21–11) produces limonene, an energy dense diesel jet fuel drop-in additive, at a titer of 4 mg/L over a 4-day incubation period. In this study, we use the state-of-the-art whole-cell characterization tool, isotopically non-stationary 13C metabolic flux analysis (INST-13CMFA) to determine intracellular fluxes through the pathways of central metabolism for the limonene producing strain and wild type strain of Synechococcus sp. PCC 7002. We find similar flux distribution in the Calvin-Benson-Bassham cycle, photorespiration, oxidative pentose phosphate pathway, and oxidative tricarboxylic acid cycle. The key difference between strains is observed in the production of pyruvate. The limonene producing strain displays significantly higher flux through the amphibolic pathways of phosphoenolpyruvate carboxylase and the malic enzyme to synthesize pyruvate, while the wild type strain uses pyruvate kinase in a single step. Our findings suggest that this flux distribution is a mechanism to recover a physiologically optimal ratio of ATP to NADPH. The upregulation of this amphibolic pathway may act to restore the physiological ATP:NADPH ratio that has been disturbed by limonene biosynthesis. This study demonstrates the value of INST-13CMFA as a tool for cyanobacterial strain engineering and provides new avenues of research for improving limonene production in Synechococcus.

Strategies to enhance enzymatic hydrolysis of lignocellulosic biomass for biorefinery applications: A review

Global interest in lignocellulosic biorefineries has increased in the recent past due to technological advancements in sustainable and cost-effective production of numerous commodity and speciality chemicals and fuels from renewable lignocellulosic biomass (LCB). As a result, the market value of biorefinery products has also increased over the time, with an estimated worth of USD 867.7 billion by 2025. However, biorefinery operations, especially enzymatic hydrolysis, suffer from many challenges that limits the cost-effectiveness of conversion of LCB. Therefore, it is essential to understand and address these challenges in future biorefineries. The paper focuses on recent trends and challenges in enzymatic hydrolysis of LCB during lignocellulosic biorefinery operation for greener synthesis of energy, fuels, chemicals and other high-value products. Insights into the gaps in knowledge and technological challenges have also been addressed together with focus on future research needs and perspectives of enzymatic hydrolysis of LCB for biorefinery applications.

Cooling Crystallization with Complex Temperature Profiles on a Quasi-Continuous and Modular Plant

Volatile markets and increasing demands for quality and fast availability of specialty chemical products have motivated the rise of small-scale, integrated, and modular continuous processing plants. As a significant unit operation used for product isolation and purification, cooling crystallization is part of this trend. Here, the small-scale and integrated quasi-continuous filter belt crystallizer (QCFBC) combines cooling crystallization, solid-liquid separation, and drying on a single apparatus. This contribution shows the general working principle, different operation modes, and possibilities of temperature control with the modular setup. For precise temperature control in cooling crystallization, Peltier elements show promising results in a systematic study of different operation parameters. Sucrose/water was used as a model substance system. The results confirm that seed crystal properties are the most important parameter in crystallization processes. Additionally, an oscillating temperature profile has a narrowing effect on the crystal size distribution (CSD). The integrated, small-scale, and modular setup of the QCFBC offers high degrees of flexibility, process control, and adaptability to cope with future market demands.

Coordinated markets for furfural and levulinic acid from residual biomass: A case study in Guanajuato, Mexico

Combustion of residual (waste) biomass represents an environmental hazard and a lost economic opportunity. The production of specialty chemicals provides a more attractive pathway to dispose of residual biomass; however, a problem that arises in recovering products from waste is that there are currently no well-established markets that bring together all stakeholders involved (e.g., biomass production, collection, transportation, and processing). In this context, coordination is essential as all the stakeholders in the supply chain (SC) depend on the revenue generated from the derived products. In this work, we propose a market coordination framework for the production of levulinic acid and furfural from lignocellulosic biomass (obtained from agricultural residues). Coordination brings a number of important economic benefits that would be difficult to achieve under existing markets (which are uncoordinated and based on peer-to-peer transactions). We demonstrate insights provided by our framework by using a case study for the State of Guanajuato in Mexico. Our results indicate that production of 330,000 tonnes per year of levulinic acid and 394,000 tonnes per year of furfural can be achieved. This constitutes 3% of the annual global demand for methyltetrahydrofuran. The SC is designed around a single biorefinery and the SC creates a total value of 3.57 billion USD per year and draws 64.65% of the available biomass supply. Our results also indicate that this market would avoid the generation of 850,000 tonnes of CO2 annually (corresponding to a 34% reduction in emissions from the combustion of agricultural residues). As such, the deployment of such a market can bring both economic and environmental benefits.

Acetic acid conversion to ketene on Cu2O(1 0 0): Reaction mechanism deduced from experimental observations and theoretical computations

Ketene, a versatile reagent in production of fine and specialty chemicals, is produced from acetic acid. We investigate the synthesis of ketene from acetic acid over the (3,0;1,1) surface of Cu2O(100) through analysis of the adsorption and desorption characteristics of formic and acetic acids. The results allow us to establish a reaction mechanism for ketene formation. Observations from x-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy, and temperature programmed desorption (TPD), supported by a comparison with formic acid results, suggest that acetic acid reacts with Cu2O through deprotonation to form acetate species coordinated to copper sites and hydroxylation of nearby surface oxygen sites. For formic acid the decomposition of adsorbed formate species results in desorption of CO2 and CO while, for acetic acid, high yields of ketene are observed at temperature >500 K. Modeling by density functional theory (DFT) confirms the strong interaction of acetic acid with the (3,0;1,1) surface and the spontaneous dissociation into adsorbed acetate and hydrogen atom species, the latter forming an OH-group. In an identified reaction intermediate ketene binds via all C and O atoms to Cu surface sites, in agreement with interpretations from XPS. In the vicinity of the adsorbate the surface experiences a local reorganization into a c(2 × 2) reconstruction. The total computed energy barrier for ketene formation is 1.81 eV in good agreement with the 1.74 eV obtained from TPD analysis. Our experimental observations and mechanistic DFT studies suggests that Cu2O can operate as an efficient catalyst for the green generation of ketene from acetic acid.