Production Of Fine Chemicals Research Articles

Atomically Dispersed Dual Metal Sites Boost the Efficiency of Olefins Epoxidation in Tandem with CO2 Cycloaddition.

Tandem catalysis provides an economical and energy-efficient process for the production of fine chemicals. In this work, we demonstrate that a rationally synthesized carbon-based catalyst with atomically dispersed dual Fe-Al sites (ADD-Fe-Al) achieves superior catalytic activity for the one-pot oxidative carboxylation of olefins (conversion ∼97%, selectivity ∼91%), where the yield of target product over ADD-Fe-Al is at least 62% higher than that of monometallic counterparts. The kinetic results reveal that the excellent catalytic performance arises from the synergistic effect between Fe (oxidation site) and Al sites (cycloaddition site), where the efficient CO2 cycloaddition with epoxides in the presence of Al sites (3.91 wt %) positively shifts the oxidation equilibrium to olefin epoxidation over Fe sites (0.89 wt %). This work not only offers an advanced catalyst for oxidative carboxylation of olefins but also opens up an avenue for the rational design of multifunctional catalysts for tandem catalytic reactions in the future.

Isolation and evaluation of strong endogenous promoters for the heterologous expression of proteins in Pichia pastoris.

The heterologous expression of biosynthetic pathway genes for pharmaceutical or fine chemical production usually requires to express more than one gene in the host cells. In eukaryotes, the pathway flux is typically balanced by controlling the transcript levels of the genes involved. It is difficult to balance the stoichiometric fine-tuning of the reaction steps of the pathway by acting on one or two promoters. Furthermore, the promoter used should not be identical to avoid loss of inserted genes by recombination or dilute its transcription factors. Based on RNA-seq data, 18 candidate genes with the highest transcription levels at three carbon sources (glucose, glycerol and methanol) were selected and their promoter regions were isolated from GS115 genome. The performance of these promoters on the level of protein production was evaluated using LacZ and EGFP genes as the reporters, respectively. These isolated promoters all exhibited activity to express LacZ gene. Using LacZ as a reporter, of the 18 promoter candidates, 9 promoters showed higher expression levels for the reporter compare to pGAP, a strong promoter widely used for constitutive expression of heterologous proteins in Pichia pastoris. These promoters with high expression levels were further employed to evaluate secreted expression using EGFP as a reporter. 6 promoters exhibited stronger protein expression compare to pGAP. Interestingly, the protein expression driven by pFDH1 was slightly higher than that of commonly used pAOX1 at methanol, and methanol-induced expression of pFDH1 was not repressed by glycerol. The various promoters identified in this study could be used for heterologous expression of biosynthetic pathway genes for pharmaceutical or fine chemical production. the methanol-induced pFDH1 that is not repressed by glycerol is an attractive alternative to pAOX1 and may provide a novel way to produce heterologous proteins in Pichia pastoris.

Isophotonic reactor for the precise determination of quantum yields in gas, liquid, and multi-phase photoreactions

Photocatalytic processes are an emerging field with a multitude of potential applications ranging from waste and wastewater treatment over fine chemical production to artificial photosynthesis. Knowing the quantum yield in a photoreaction is thereby essential to both, the selection of suitable photocatalysts and the design of optimized photoreactors. Nevertheless, the precise determination of quantum yields as function of the operating conditions is still a challenge without standardized and reliable procedures and apparatuses. Herein a novel approach for the accurate determination of quantum yields based on a tailored, 3D-printable photoreactor and 3D optical modelling is reported. Besides wavelength, temperature, and reactant concentration control, the unique optical design of an isophotonic reactor enables the control of the local volumetric rate of photon absorption to be homogeneous throughout the reaction volume. The validity of the approach is demonstrated by determining the quantum yield of the standard potassium ferrioxalate actinometer. Further, the adaptability to any gas, liquid, or multi-phase photoreaction is outlined by showcasing the ability of the approach with an exemplary aerogel-supported titania-based methanol reforming photocatalyst. The revealed subtlety and complex nature of the quantum yield in the methanol reforming system highlights the need for meticulous analysis and standardization of the determination of quantum yields and thereby underlines the value of the proposed approach. Software tools and print files provided alongside the publication facilitate adaptation and further development of the approach by researchers in the field.

Oxidative C-C bond cleavage of lignin via electrocatalysis.

Lignin, which is an important component of biomass in nature and is constantly produced in industry, becomes potential raw material for sustainable production of fine chemicals and biofuels. Electrocatalysis has been extensively involved in the activation of simple molecules and cleavage-recasting of complex scaffolds in an elegant environment. As such, electrocatalytic cleavage of C−C(O) in β-O-4 model molecules of lignin to value-added chemicals has received much attention in recent years. This mini-review introduces various anodes (e.g., Pb, Pt, Ni, Co., and Ir) developed for electro-oxidative lignin degradation (EOLD) under mild conditions. Attention was placed to understand the conversion pathways and involved reaction mechanisms during EOLD, with emphasis on the product distribution caused by different electrodes.

Batching and scheduling in a continuous-discrete hybrid flowshop: Lagrangian relaxation-based heuristic algorithms

ABSTRACT We study a two-stage hybrid flow shop problem arising from a fine chemicals production facility, where the first stage is a continuous chemical reaction process and the second stage is a discrete filling-packaging process. The objective is to minimise the total weighted completion time through batching of the jobs and scheduling of the batches at first stage and scheduling of the jobs at second stage. We formulate the problem as a mixed integer programming model and develop a Lagrangian relaxation-based framework for solving it, where the original problem is decomposed into family-level subproblems, and each subproblem is transformed into a set-partitioning problem. The subproblems are solved to optimality via branch and price algorithm. We also propose two heuristic algorithms for reducing computational efforts without much loss of solution quality. Finally, we conduct computational experiments with both randomly generated and real data sets to test the performance of the three proposed algorithms and demonstrate that the algorithms perform efficiently.

Synthesis and Applications of Periodate for Fine Chemicals and Important Pharmaceuticals

An emerging interest for the application of periodate in the synthesis of active pharmaceutical ingredients (APIs) and for the valorization of renewable feedstock is eminent. However, periodate exhibits a high molecular mass, is expensive compared to other common bulk-oxidizers and is used only reluctantly in technical applications. Recently, a new and green electrochemical synthesis was established. The preparation and regeneration method for periodate lowers costs and enables the use of periodate in the synthesis of regulated products. This review will briefly introduce the key innovations in the electrochemical synthesis of periodate and will survey the most important applications of periodate in the production of fine chemicals.

An efficient electrochemical oxidation of C(sp3)-H bond for the synthesis of arylketones

An efficient electrochemical oxidation of C-H (sp3) bond was developed with carbon rod as the anode and platinum counter electrode as well as the routine tetrabutylammonium tetrafluoroborate as electrolyte in an undivided cell. Using water as both co-solvent and sole oxygen source, more than 20 examples of arylketones were facilely synthesized in good to excellent yields (up to 92%) in the air under the constant current of 6 mA without external oxidants, base or mediators. The possible electrochemical reaction mechanism was also proposed. And the key intermediate 2u of pharmaceutical dyclonine was highly efficiently prepared through applying this electrochemical method. This electrochemical driven oxidation reaction has the advantages of simple operation and mild reaction conditions, as will provide a sustainable approach for alkane oxidation to aldehyde or ketone. We envision that our method will be useful for applications in the future industrial production of fine organic chemicals.

Visible light enhanced photosynthesis of C-C bonds using PdO/Pd@PEDOT nanocomposite

Facile utilization of abundant and freely available solar energy in the production of fine chemicals is currently recognized as an effective strategy for sustainable chemical production. We are hereby reporting one of the best visible light active photocatalysts for C-C bond formation. The photocatalyst is a heterojunction nanocomposite of PdO/Pd with poly(3,4-ethylenedioxythiophene) (PdO/Pd@PEDOT HNC). It was synthesized via one pot chemical oxidative polymerization of EDOT with K2PdCl4. Uniform spherical morphology of the nanocomposite was achieved using a solvent assisted, and template free approach. PdO/Pd@PEDOT HNC consisted of very small Pd nanoparticles with dual oxidation states [here, Pd (II) and Pd (0)] embedded in the PEDOT matrix. It showed excellent electron-hole pair separation capabilities under visible light due to the formation of a straddling type of heterojunction between PdO and semiconducting PEDOT. PdO/Pd nanoparticles forms strong chemical interaction with PEDOT via Pd-O and Pd-S bonds in the HNC. These interactions make it a highly stable photocatalyst which can be recycled up to seven times without any significant loss of activities. Further, a novel route for the synthesis of uniform Pd4S nanostructures using a template free strategy could also be achieved.

Integration of adaptive syntheses in the sustainable production of biofuels and chiral fine chemicals

Integration of adaptive syntheses in the sustainable production of biofuels and chiral fine chemicals

Performic acid pre-treatment of poplar biomasses grown on a contaminated area for enhanced enzymatic digestibility: A viable route to obtain fine-products and recovery of contaminants

Biomasses obtained from green remediation strategies can represent a new valuable feedstock for obtaining fine chemicals and/or next generation liquid fuels. A sustainable chain of technologies for recovering chemicals from poplar grown in a multi-contaminated area is presented here in this work. A pre-treatment based on the use of performic acid (generated in situ from formic acid and hydrogen peroxide) was designed and tested. The effect of this pre-treatment was measured in terms of delignification, the increased enzymatic digestibility of the solid residues, and final destination of the mineral components initially present in poplar biomass. Upon treatment with performic acid at 1.75, 3.5 and 7 M, the content of lignin in the residual biomasses resulted as being significantly reduced: 28.5, 92.8 and 100% of initial lignin were removed and dissolved. After this pre-treatment, most of minerals initially present in poplar biomass were dissolved during the generated aqueous phase. In concomitance, a large part of the initial lignin and xylose were also dissolved. The solid residues obtained from the pre-treatment phase were then subjected to hydrolysis. Enzymatic digestibility was proven to be already effective on samples pre-treated with 3.5 M performic acid at 55 °C. Indeed, even when lignin was not completely removed (>75%), the cellulose in the residual biomasses was completely hydrolysed in glucose through a commercial cellulase (from Trichoderma reesei). Finally, the aqueous solution obtained from enzymatic hydrolysis was effectively reacted in presence of AlCl3·6H2O (1%) and sulphuric acid (0.5%) at 150 °C for 45 min. A final yield of 68.2% of levulinic acid and 4.8% of hydroxymethyl furfural were eventually obtained. Through this process, not only were the majority of metals coming from the plant-assisted bioremediation process/strategy confined to an aqueous solution, but also residual poplar biomasses were valorised by generating platform molecules which might find applications in the production of fine-chemicals.

Fast room-temperature hydrogenation of nitroaromatics on Pd nanocrystal-boron cluster/graphene oxide nanosheets

The reduction of nitroaromatics to aminoaromatics is essential for fine chemical production and effective sewage treatment. However, the activity of an external catalyst is essential for the reaction. In this study, Pd nanocrystals were anchored in situ on two-dimensional graphene oxide (GO), which acted as a catalyst support with high specific surface area. The oxygen-containing groups on the surface of GO bonded to the functionally rich boron clusters through hydrogen bonding interactions. A mildly reducible closed-dodecahydrododecaboric acid anion cluster (closo‑[B12H12]2–) was employed as the target site. The mild reducibility of closo‑[B12H12]2– resulted in a wide dispersion of ultrafine Pd nanocrystals on GO. Under ambient conditions, Pd/BGO rapidly hydrogenated nitroaromatics, such as 4-nitrophenol, to aminoaromatics with approximately 100% efficiency. Moreover, Pd/BGO retained its high catalytic activity for the hydrogenation/reduction of 4-nitrophenol after five catalytic cycles. Therefore, Pd/BGO could be a promising and economically viable candidate for various practical applications. The proposed innovative preparation strategy and highly efficient catalytic activity suggested the effective performance of closo‑[B12H12]2– as nanometal nucleation target sites. In addition to providing an alternate route for preparing supported nanometals, this study presents a stable and efficient catalyst for the hydrogenation of nitroaromatics.

Electrochemical Structure-Reactivity Relationships in NAD+ Mimetics: Towards Recyclable Cofactors for Protein-Catalyzed Reactions

The chemical engineering industry relies increasingly on enzyme-catalyzed reactions in the production of fine chemicals, value-added compounds, and commodity chemicals. However, many attractive transformations, such as the selective reduction of ketones and alkenes, depend on cofactors that are prohibitively expensive for application on an industrial scale. One such cofactor, nicotinamide adenine dinucleotide (NAD+/NADH), is utilized by >20% of all enzymes but is required in generally super-stoichiometric amounts and currently has no efficient means for recycling. Direct electrochemical reduction of NAD+ is an attractive approach for regeneration of the biological cofactor; however, electrolysis often results in relatively small amounts of biologically active NADH due to a parasitic dimerization. Recent work has demonstrated the ability of lower-cost NADH mimetics to exhibit enzymatic activity, sometimes exceeding that of NADH itself, although still required in at least stoichiometric amounts. Subsequently, we considered the possibility of designing NADH biomimetics to simultaneously maintain enzymatic activity and minimize deleterious side reactions, thereby allowing them to be electrochemically recycled. We will describe our recent progress in both measuring and modeling the electrochemical dimerization and regeneration rates of NADH mimetics. We have employed Electrochemical Impedance Spectroscopy to quantify rapid dimerization rates observed for electrochemically reduced NADH biomimetics. By combining this electroanalytical approach with density functional theory (DFT) modeling and machine learning algorithms, we are elucidating structure-function relationships to design more efficiently regenerable mimetics.

(Invited) Process Intensification of Electrochemical Systems for CO2 and Biomass Valorization

Valorization of CO2 and biomass waste streams via electrochemical conversions is a sustainable alternative for the production of fine chemicals and commodity chemicals. This topic has gained a lot of attention in the past decades and major research efforts have been put into it. Key advances has been achieved in the field of material development, where, novel catalysts have been synthesized, developed and have demonstrated to increase the efficiency and selectivity towards the targeted products. Relatively to the large number of studies focused on material development, limited studies are focused on process development, reactor optimization and product separation. Although material development is of paramount importance to achieve an adequate electrochemical reaction performance, it is only the first step needed in order to develop a competitive technology. Process development offers the possibility of enhancing the overall performance of the technology by looking not only at the reaction level, but finding engineering solutions to overcome critical limitations. Process development is essential in order to accelerate the technology towards its envisioned application and advance towards commercial realization. In this talk, we will present several optimization strategies (beyond material development) that helped increase the overall performance of several electrochemical conversion processes, as well as the economic profitability of the complete system.In addition, in order to advance the technology on the TRL scale and have a positive market potential, the technology needs to be evaluated in several aspects such as the scaling-up challenges, its cost competitiveness and its climate benefits. For this, it is crucial to consider the complete value chain, and evaluate not only the electrochemical reaction but also the upstream and the downstream processes. A complete system approach is paramount for the development of competitive technologies. In this talk we will also show several examples on different process intensification strategies and its benefits on the economic potential of them.

Solar‐Driven Overproduction of Biofuels in Microorganisms

AbstractMicrobial cell factories reinvigorate current industries by producing complex fine chemicals at low costs. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is the main reducing power to drive the biosynthetic pathways in microorganisms. However, insufficient intrinsic NADPH limits the productivity of microorganisms. Here, we report that supplying microorganisms with long‐lived electrons from persistent phosphor mesoporous Al2O3 (meso‐Al2O3) can elevate the NADPH level to facilitate efficient fine chemical production. The defects in meso‐Al2O3 were demonstrated to be highly efficient in prolonging electrons’ lifetime. The long‐lived electrons in meso‐Al2O3 can pass the material–microorganism interface and power the biosynthetic pathways of E. coli to produce jet fuel farnesene. This work represents a reliable strategy to design photo‐biosynthesis systems to improve the productivity of microorganisms with solar energy.

Solar-Driven Overproduction of Biofuels in Microorganisms.

Microbial cell factories reinvigorate current industries by producing complex fine chemicals at low costs. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is the main reducing power to drive the biosynthetic pathways in microorganisms. However, insufficient intrinsic NADPH limits the productivity of microorganisms. Here, we report that supplying microorganisms with long-lived electrons from persistent phosphor mesoporous Al2 O3 (meso-Al2 O3 ) can elevate the NADPH level to facilitate efficient fine chemical production. The defects in meso-Al2 O3 were demonstrated to be highly efficient in prolonging electrons' lifetime. The long-lived electrons in meso-Al2 O3 can pass the material-microorganism interface and power the biosynthetic pathways of E. coli to produce jet fuel farnesene. This work represents a reliable strategy to design photo-biosynthesis systems to improve the productivity of microorganisms with solar energy.

Control of selectivity in organic synthesis via heterogeneous photocatalysis under visible light

Organic synthesis driven by heterogeneous catalysis is a central research theme to both fundamental research and industrial production of fine chemicals. However, the employment of stoichiometric strong oxidizing or reducing reagents (e.g., K₂Cr₂O₇ and LiAlH₄) and harsh reaction conditions (e.g., high temperature and pressure) always leads to the products of overreaction and other by-product residues (e.g., salt and acid waste). Thus the poor control of product selectivity and tremendous energy consumption result in the urgent demand to develop novel technologies for heterogeneous catalysis. Given the current global theme of development in CO₂ reduction and sustainable energy utilization, one promising protocol is heterogeneous photocatalysis. It enables sustainable solar-to-chemical energy conversion under mild conditions (e.g., room temperature, ambient pressure, and air as the oxidant) and offers unique reaction pathways for improved selectivity control. To accurately tailor the selectivity of desired products, the electronic structure (e.g., positions of valence-band maximum and conduction-band minimum), geometric structure (e.g., nanorod, nanosheet, and porous morphology), and surface chemical micro-environment (e.g., vacancy sites and co-catalysts) of heterogeneous photocatalysts require rational design and construction. In this review, we will briefly analyze some effective photocatalytic systems with the excellent regulation ability of product selectivity in organic transformations (mainly oxidation and reduction types) under visible light irradiation, and put forward opinions on the optimal fabrication of nanostructured photocatalysts to realize selective organic synthesis.

A Career in Catalysis: Avelino Corma

As one of the most influential scientists in the field of heterogeneous catalysis and materials science, Prof. Avelino Corma has made significant contributions in many diverse fields, spanning over solid catalysts for petrochemistry, solid catalysts for production of fine chemicals, synthesis of microporous and mesoporous materials, development of inorganic–organic hybrid materials, supported metal catalysts (from isolated metal atoms to nanoclusters and nanoparticles) and photochemistry with solid materials. These experimental approaches are complemented with characterization of solid materials with advanced spectroscopy and microscopy techniques as well as theoretical calculations/modeling. The aim of this Account is to overview Avelino’s distinguished scientific career and highlight the most remarkable achievements made in his research activities during >40 years. We attempt to show the evolution of Avelino’s research topics in his group throughout his career and the approaches that Avelino has chosen to tackle the challenges encountered. The research paradigm developed by Avelino and his team can be inspiring to the researchers in the field of materials science who are striving to translate the knowledge generated in fundamental studies into practical applications for addressing the new scientific challenges encountered in building a sustainable world.

A highly sulfur resistant and stable heterogeneous catalyst for liquid-phase hydrogenation

Developing sulfur resistant and stable hydrogenation catalysts with a high activity is of great economic and environmental interest for the production of value-added fine chemicals, as it allows the use of crude industrial level raw materials as reactant, prevents environmental unfriendly stoichiometric reduction and cuts down energy-intensive separation/purification procedures. Here we show the metallic Ni nanoparticle well-enclosed in multilayer N doped graphene shells for the catalytic hydrogenation of nitrobenzene derivatives. The nickel core promoted multilayer N doped graphene shell not only maintains the hydrogenation ability but also create a differentiate surface electronic state preventing the poisoning of vulnerable metal by S impurities. The catalytic performance has met the product requirement of hydrogenation of industrial raw materials including 4.00 wt% inorganic/organic sulfur poisoning substances, excessive acid residue and concentrated salts.

Analysis of the Existing Problems and Countermeasures of Fine Chemical Production Management

Analysis of the Existing Problems and Countermeasures of Fine Chemical Production Management

The importance of Brønsted acid sites on C[sbnd]O bond rupture selectivities during hydrogenation and hydrogenolysis of esters

Esters represent an important class of reagents and intermediates for the production of fine chemicals and polymers. In prior studies of homogeneous catalysis, molecular complexes have been reported to selectively cleave either carbonyl CO or acyl CO bonds of ester to ether or alcohols, respectively. In contrast, reactions of esters and H2 upon heterogeneous catalysts typically cleave acyl CO bonds and produce alcohols. Here, we demonstrate that the proximity of Brønsted acid sites to Pd nanoparticles and the thermodynamic strength of these Brønsted acid sites influence the rates and selectivities toward CO bond cleavage pathways either to ethers or alcohols during reactions of esters over bifunctional solid catalysts. The combined results from rate measurements as functions of H2 pressure, ester conversion, and methods to combine Pd nanoparticles and acidic supports; kinetic isotope effects; in situ Brønsted acid site titrations; and calorimetric assessments of Brønsted acid strength provide evidence for bifunctional pathways that require proximity between Brønsted acid sites and Pd atoms to form ethers. These findings suggest that Brønsted acid sites near Pd nanoparticles and with lower deprotonation energies promote the direct reduction of esters to ethers by cleaving the carbonyl CO bond. Taken together, these data indicate that direct reduction of esters to ethers involves the hydrogenation of the ester reactant to form hemiacetal at Pd nanoparticles, followed by dehydration of the hemiacetal at proximal acid sites, and subsequent hydrogenation of the enol ether. In comparison, hydrogenolysis of acyl CO bonds of the ester reactant involves the reaction of a hydrogenated intermediate (plausibly hemiacetal) upon Pd nanoparticles to form the corresponding alcohol and aldehyde products. Among the materials examined, Pd nanoparticles supported on WO3 catalyze the direct reduction of esters and lactones to corresponding ethers and remain stable over extended periods of time on stream (∼42 h). These findings offer a foundation for further design and improvement of heterogeneous catalysts for the selective reduction of esters and other challenging hydrogenations.