Manufacture Of Industrial Chemicals Research Articles

Optimized design of macro‐microreactor for scale‐up of liquid–liquid chemical processes

AbstractThe scale‐up of microreactor‐based flow chemical process represents a grand challenge in chemical engineering. The small characteristic size (<1000 μm) of a typical microreactor leads to not only microscale effect (process intensification) but also low throughput. Here, we report macro‐microreactor to achieve scale‐up of liquid–liquid chemical operation with process intensification. By incorporating the designed internals based on computational fluid dynamics, the characteristic size of the macro‐microreactor is expanded into 3000–4000 μm. The optimized design of macro‐microreactor with helical‐shaped internal exhibits both similar or even stronger microscale effect and high throughput in contrast to the typical microreactor. For the liquid–liquid chemical process, seven times higher mass transfer coefficient and about half reduction of the pressure drop are realized. These macro‐microreactors would find further applications in industrial chemical manufacturing.

Homologous Pairs of Low and High Temperature Originating Proteins Spanning the Known Prokaryotic Universe

Stability of proteins at high temperature has been a topic of interest for many years, as this attribute is favourable for applications ranging from therapeutics to industrial chemical manufacturing. Our current understanding and methods for designing high-temperature stability into target proteins are inadequate. To drive innovation in this space, we have curated a large dataset, learn2thermDB, of protein-temperature examples, totalling 24 million instances, and paired proteins across temperatures based on homology, yielding 69 million protein pairs - orders of magnitude larger than the current largest. This important step of pairing allows for study of high-temperature stability in a sequence-dependent manner in the big data era. The data pipeline is parameterized and open, allowing it to be tuned by downstream users. We further show that the data contains signal for deep learning. This data offers a new doorway towards thermal stability design models.

Why Should the Reaction Order of a Bimolecular Reaction be 2.33 Instead of 2?

Predicting the reaction kinetics, that is, how fast a reaction can happen in a solution, is essential information for many processes, such as industrial chemical manufacturing, refining, synthesis and separation of petroleum products, environmental processes in air and water, biological reactions in cells, biosensing, and drug delivery. Collision theory was originally developed to explain the reaction kinetics of gas reactions with no dilution. For a reaction in a diluted inert gas solution or a diluted liquid solution, diffusion often dominates the collision process. Thus, it is necessary to include diffusion in such a calculation. Traditionally, the classical Smoluchowski rate is used as a starting point to predict the collision frequency of two molecules in a diluted solution. In this report, a different collision model is derived from the adsorption of molecules on a flat surface. A surprising result is obtained, showing that the reaction order for bimolecular reactions should be 2 and 1/3 instead of 2, following a fractal reaction kinetics.

Electrochemical recycling of homogeneous catalysts.

Homogeneous catalysts have rapid kinetics and keen reaction selectivity. However, their widespread use for industrial catalysis has remained limited because of challenges in reusability. Here, we propose a redox-mediated electrochemical approach for catalyst recycling using metallopolymer-functionalized electrodes for binding and release. The redox platform was investigated for the separation of key platinum and palladium homogeneous catalysts used in organic synthesis and industrial chemical manufacturing. Noble metal catalysts for hydrosilylation, silane etherification, Suzuki cross-coupling, and Wacker oxidation were recycled electrochemically. The redox electrodes demonstrated high sorption uptake for platinum-based catalysts (Qmax up to 200 milligrams of platinum per gram of adsorbent) from product mixtures, with up to 99.5% recovery, while retaining full catalytic activity over multiple cycles. The combination of mechanistic studies and electronic structure calculations indicate that selective interactions with anionic intermediates during the catalytic cycle played a key role in the separations. Last, continuous flow cell studies support the scalability and favorable technoeconomics of electrochemical recycling.

Practical and Selective sp3 C-H Bond Chlorination via Aminium Radicals.

The introduction of chlorine atoms into organic molecules is fundamental to the manufacture of industrial chemicals, the elaboration of advanced synthetic intermediates and also the fine‐tuning of physicochemical and biological properties of drugs, agrochemicals and polymers. We report here a general and practical photochemical strategy enabling the site‐selective chlorination of sp3 C−H bonds. This process exploits the ability of protonated N‐chloroamines to serve as aminium radical precursors and also radical chlorinating agents. Upon photochemical initiation, an efficient radical‐chain propagation is established allowing the functionalization of a broad range of substrates due to the large number of compatible functionalities. The ability to synergistically maximize both polar and steric effects in the H‐atom transfer transition state through appropriate selection of the aminium radical has provided the highest known selectivity in radical sp3 C−H chlorination.

Practical and Selective sp3C−H Bond Chlorination via Aminium Radicals

AbstractThe introduction of chlorine atoms into organic molecules is fundamental to the manufacture of industrial chemicals, the elaboration of advanced synthetic intermediates and also the fine‐tuning of physicochemical and biological properties of drugs, agrochemicals and polymers. We report here a general and practical photochemical strategy enabling the site‐selective chlorination of sp3C−H bonds. This process exploits the ability of protonatedN‐chloroamines to serve as aminium radical precursors and also radical chlorinating agents. Upon photochemical initiation, an efficient radical‐chain propagation is established allowing the functionalization of a broad range of substrates due to the large number of compatible functionalities. The ability to synergistically maximize both polar and steric effects in the H‐atom transfer transition state through appropriate selection of the aminium radical has provided the highest known selectivity in radical sp3C−H chlorination.

Effect of Fe2O3 loading on CuO/CNT photocatalyst for degradation of p-Chloroaniline

Chloroaniline and its derivatives are generated from industrial chemical manufacturing processes including agricultural chemical, azo dyes and pigments, pesticides and herbicides. These compounds are found to be toxic and dangerous to aquatic and human life. Hence, their discharge into the environment must be regulated. Photocatalytic degradation is one of a promising method to remove such compounds due to its safety, low energy consumption and high efficiency. In this study, the research focused on the effect of iron oxides (Fe2O3) loading (5-50 wt%) on copper-carbon nanotubes (CuO/CNT) photocatalyst for degradation of p-chloroaniline (PCA) under visible light irradiation. The synthesized catalysts were characterized using Fourier Transform Infrared Spectroscopy to analyze its functional groups. Besides Fe2O3 loading, various parameters such as effect of PCA pH solution (3-11), catalyst dosage (0.125- 0.625 g L−1) as well as PCA initial concentration (10-100 mg L−1) were investigated. It was found that the highest degradation (75 %) of 10 mg L−1 PCA was achieved using 0.325 g L−1 10 wt% Fe2O3/50 wt% CuO/CNT at pH 7. Kinetics study showed that the PCA photodegradation followed pseudo first-order Langmuir-Hinshelwood model. It is believed that the Fe2O3/CuO/CNT can be a potential photocatalyst for degrading organics pollutant efficiently.

Dust removal and purification of calcium carbide furnace off-gas

A large amount of CO contained in calcium carbide furnace off-gas can be recycled and used as an important raw material for C1 (one carbon) industrial chemical manufacturing. The key to the recovery is the removal of dust and gaseous impurities from the off-gas. For this purpose, an industrial device has been used for removing the dust. This consists of a laboratory-scale fixed-bed reactor with two kinds of adsorbents, prepared in our laboratory, for removing HCN and COS. The results show that the dust content after the dedusting process was less than 20mg/m3. The dust particles are composed of microspheres, with an obvious tendency to agglomerate, and with an average diameter of about 6.71μm. After adsorption, the outlet concentrations of both HCN and COS were less than 1mg/m3. In order to remove HCN, activated carbon (AC) was used, impregnated with 0.15mol/L Cu(CH3COO)2 solution. The optimum calcination temperature was 350°C. The AC, modified with Cu(CH3COO)2, was examined by means of N2-BET and X-ray photoelectron spectroscopy (XPS) before and after off-gas treatment. The results indicate that the chemisorption products were mainly present in the AC micropores and mesopores, with radius 0.81–1.51nm. After dust removal and purification, the calcium carbide furnace off-gas is fit for use as a raw material in the C1 chemical manufacturing industry.

The Comité Consultatif pour la Quantité de Matière: a brief review of its origin and present activities

International traceability to the SI is increasingly demanded for measurements in chemistry. These concern measurements made not only for industrial chemical manufacturing but also for checking the safety of a wide range of food and agricultural products, for environmental protection, for medicine, as well as for a multitude of regulatory purposes. This article outlines the role that the Comité Consultatif pour la Quantité de Matière (CCQM) can play in establishing traceability at the highest level for such measurements. A brief account is given of the actions taken so far by the Committee. These include the precise description of primary methods, the meaning of traceability for measurements in chemistry and the organization of some key international comparisons designed to test the procedures drawn up to guide them. Plans for future work are described.

Acrylate fermentations.

It is well recognized that non-renewable resources such as natural gas and oil are limited in availability. As a consequence, considerable effort is being expended to develop alternative technologies for the manufacture of industrial chemicals (ethanol, acetic acid, 2,3-butanediol, and acetone/butanol) which utilize renewable raw materials. It is in this context that we have sought to investigate the potential of microbially catalyzed reactions for the production of acrylic acid from a biomass which is one of renewable solar energy resources.KeywordsMethylene BlueAcrylic AcidPropionic AcidPropionate OxidationAnaerobic FermentationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.