Chemical Engineering Research & Design最新文献

The valorisation of green hydrogen and captured CO₂ to produce chemicals or energy carriers holds immense potential to reduce GHG emissions. Among them, formic acid (FA) is an essential chemical with diverse applications and a growing market demand. Furthermore, due to liquidity at ambient conditions and its chemical stability, it is a promising hydrogen carrier. However, its direct thermochemical synthesis from CO₂ hydrogenation still faces significant challenges due to a high thermodynamic barrier. This study presents a novel and eco-efficient process design for a 50 kta FA production from CO₂ and green H₂. Initially, CO₂ is converted to CO as an intermediate compound that undergoes a carbonylation reaction with methanol to form methyl formate, which is then hydrolysed into FA. The major challenges of this new proposed process lie in the purification of CO and the energy-intensive downstream separation of FA. The former is addressed by using the COPure™ technology, which combines chemical and physical absorption, while the latter requires the use of process intensification techniques to minimize the energy and capital expenses. The newly designed process achieves high molar yields of 95 % for CO₂ and 96 % for H₂ with a specific energy intensity of 21.8 MJ/kg of FA. Notably, the CO₂ emissions can be reduced by almost half as compared to the existing FA synthesis from fossil fuels, coupled with a 64 % reduction in electricity usage and 20 % decrease in steam requirements.

Extremely high particle stiffness and very low hardness is a serious concern in various mechanical processes in pharmaceutical manufacturing. Here we report an exceptionally high Young’s modulus (E) of ∼ 18 GPa in a drug, isoniazid (INH). This is one of the highest experimentally determined values among all reported pharmaceutical molecular crystals, which we attribute to the presence of a strong three-dimensional (3D) hydrogen bonding network (HBN). Further, we successfully reduced the 3D HBN in INH to 2D in its cocrystal using a co-former, 3,4-dimethylbenzoic acid (DMBA), where its two hydrophobic groups act like protecting groups at supramolecular level and prevent the extension of HBN. This reduced the E in the 1:1 cocrystal, INH-DMBA, by many folds and markedly improved its powder tabletability. To the best of our knowledge, this is the first reliable molecular level approach to alter the stiffness of pharmaceutical crystals and tabletability improvement in a predictable manner, hence, is important in the context of crystal engineering.

A double coaxial tube configuration of atmospheric pressure plasma jet (APPJ) was compared with a single tube one for open air plasma polymerization. The effectiveness on minimizing the influence of ambient air during the deposition process was shown for a double tube APPJ i.e. Ar gas fed into the outer glass tube acted as a shielding gas. The inner tube, acted as the powered electrode was fed with a mixture of Ar gas with the precursor, i.e., toluene vapor, a non-oxygen containing precursor. The dynamics of gas flow and its dependence on composition was investigated with a Schlieren imaging system. Coatings obtained with both configurations were analyzed by fourier transform infra-red (FTIR) and x-ray photoelectron spectroscopy (XPS). The results show clearly that the argon shielding gas largely protects the diffusion of oxygen in the deposition zone, giving rise to polymers with much less oxygen incorporated in their structure, and a good retention of the aromatic rings of toluene. Furthermore, the area of the treated zone and the chemical composition of the coating deposited is highly localized (1 mm) in the double tube giving dense stable carbon films while the deposition in the single tube much bigger (6 mm), and the deposited coatings are unstable and easily washed away. Hence, the results obtained with this innovative system provide a new path in plasma polymerization and continuous treatments of large surfaces, with improved coating stability and chemical retention.

Natural gas liquefaction assisted by the nitrogen expansion process is a growing option for small-scale refineries. The liquefaction process is an energy-intensive process, so choosing a cost-effective main heat exchanger is vital. With the ever-increasing expansion of small-scale liquefaction refineries, printed circuit heat exchangers (PCHEs) are promising candidates with great efficiency due to their small dimensions and high pressure and temperature difference tolerance. In this study, to reduce the LNG temperature, curved channels with fillet corners have been replaced by straight channels. The effects of operation pressure, inclined angle (α), and pitch number (N) on thermohydraulic performance and entropy generation in methane and nitrogen channels were studied. With an increasing inclined angle, a 24.11 % reduction in total entropy generation in the methane channel and a 10.27 % decrease in the nitrogen channel occur at α=45^°and N=10. The closeness of Bijan number to 1 in the methane channel reveals the greater contribution of entropy generation due to heat transfer. For curvy channels, the performance evaluation criterion is greater than 1, which indicates that the structural change of the channel can reduce the negative effects of pressure drop. This research can make suitable steps for optimizing PCHEs in the natural gas liquefaction industry.

Nitrogen containing compounds in the liquid fuel are well-known to cause serious corrosive action on the engines and plugging of filters with the formation of gummy compounds. Hence, the removal of nitrogenated compounds from the liquid fuel is highly demanded. The current study focused on the efficient removal of indole and quinoline (as nitrogenated compounds) by Ca based metal organic framework. Formerly, Ca based metal organic framework was synthesized using eggshell wastes as source of Ca by Solvothermal [Ca-BTC (s)] and Microwave [Ca-BTC (m)] techniques. Flower and shell plates like crystals were observed under microscope for the synthesized Ca-BTC (s) and Ca-BTC (m), respectively. Purification of liquid fuel from indole and quinoline by the obtained Ca-BTC was systematically investigated. The adsorption of nitrogenated compounds followed the second order reaction and Langmuir isotherm. Microwave technique showed to be more preferable rather than solvothermal technique, for preparation of Ca-BTC with significantly higher adsorption capacity, whereas, and the affinity was higher towards quinoline compared to indole. Meanwhile, for Ca-BTC (m), the estimated maximum adsorption capacity of indole and quinoline was 490.7 mg/g and 583.4 mg/g, respectively. After 4 regeneration cycles, the adsorption capacity Ca-BTC (m) was lowered by 29 % for indole and 24 % for quinoline. The obtained results confirmed the successful using of eggshell wastes in preparation of Ca-BTC with remarkable efficiency in the liquid fuel purification with quite good recyclability.

The objective of the present study was to analyze the gasification process for the simultaneous exposure to a multi-component gasifying mixture. In a real scenario of the gasification process, char pellets from the pyrolysis zone undergo multiple non-catalytic gas-solid reactions in combustion and gasification zones. A single-char pellet gasification and combustion is studied in this study. This was done by developing a mathematical formulation, based on a grain model, for multiple reactions that also incorporated transient and non-isothermal behaviors, structural changes, and porosity changes. The developed model was validated against experimental data from the literature and was in good agreement. The variation of conversion, gasification reactivity, species’ effectiveness factor, and reactions’ effectiveness factor for various parameters were analyzed. Out of these parameters, bulk temperature, initial condition for temperature, pellet radius, and diffusivity of the gases were found to have a profound impact on the effectiveness factor of the species.

The investigation of the interactions between particles resulting from long-range hydrophobic forces has been thoroughly studied in the literature. The hydrophobic force is most likely a result of capillary forces that may occur when nanobubbles merge and create capillary bridges. Recent studies show that fine particle collection can be enhanced by introducing nanobubbles, which seems to be a positive indication of the existence of such capillary bridges. There has been a significant interest in nanobubble research in the past two decades due to their excellent stability and multitude of applications. Although this is an interesting research area, there is still a great debate about the extraordinary stability of nanobubbles. Arguably, much less is known about the underlying mechanisms responsible for their role in bubble–particle and particle–particle interactions that can potentially augment a wide range of separation processes. In this review article, we aim to examine the underlying mechanisms of nanobubble interactions with particles and bubbles that can be conveniently utilized to explain the improved particle separation efficacy. This article also discusses the current understanding of the origin of nanobubbles, including their characterization methods, existing debates, and possible reconciliation of different theories. Finally, the review discusses areas that require further research to clarify some existing issues and provides a direction where further research in the area should be headed.

The Z-scheme Fe₃O₄/BiOBr/BiOI heterojunction with magnetic recyclability was developed by a simple solvothermal approach, effectively targeting and degrading tetracycline pollutants in water that were difficult for the environment to naturally break down. The meticulously produced samples were thoroughly examined for their morphology, structural integrity, microscopic composition, chemical properties, and magnetic characteristics using a variety of analytical techniques. The tripartite Fe₃O₄/BiOBr/BiOI ensemble demonstrated exceptional photocatalytic degradation ability (87 %) towards tetracycline (TC) when guided by simulated sunlight, significantly outperforming the capabilities of pure BiOBr and BiOI. Radical trapping tests revealed that superoxide radicals (·O₂^-) and holes (h⁺) were the main components responsible for photodegradation. Fe₃O₄/BiOBr/BiOI showed increased photocatalytic efficiency, mainly because of the Z-scheme heterojunction creation that allowed for the effective separation of charge carriers generated by photosynthesis. Moreover, Fe₃O₄/BiOBr/BiOI showed remarkable stability and recyclable properties while maintaining high photocatalytic activity. The successful creation of Z-scheme heterojunction photocatalysts with magnetic recycling for the breakdown of pollutants was predicted to be made possible by this work.

Deep learning models possess limited flexibility in computational burden in model adaptation owing to the conventional use of backpropagation for model training. To address this problem, we propose an alternate training methodology inspired by the forward–forward algorithm originally designed for classification tasks. We extend this concept through a kernel-based modification, enabling its application to regression tasks, which are commonly encountered in process system modeling. Our proposed Kernel-based Forward Propagating Neural Network (K-FP-NN) eliminates backpropagation, using layer-wise updates for better adaptability. We introduce a real-time (RT) updating framework, RT-K-FP-NN, to continuously refine model parameters with new data. Results indicate that when applied to model predictive control of a continuous stirred tank reactor (CSTR) system, our approach updates the model within 100 s, achieving better performance metrics compared to backpropagation-based real-time models, which require 326 s. This framework can be applied to various dynamic systems, enhancing real-time decision-making by improving predictive accuracy and system adaptability.

As an environmental pollutant with low olfactory threshold, mercaptan foul-smelling substances have caused great harm to human production and life. Among the existing mercaptan treatment technologies, adsorption method has been widely studied and applied because of the advantages of high efficiency and renewable adsorbents. In this paper, the adsorption mechanisms of mercaptan on zeolite molecular sieves, carbon-based materials, metal-organic frameworks and metal oxides are reviewed, and it is concluded that the main mechanisms for their adsorption of mercaptan are micropore filling and chemical bonding, but some of the adsorbents also have mechanisms such as sieve effects, free radical reactions and π-π interactions. It is also pointed out that the green and low-cost modification of zeolite molecular sieves and the maintenance of the structural stability of metal-organic frameworks are the bottlenecks that need to be solved for the future development of efficient adsorption of thiols materials, and the development of composite materials of nanocarbon and metal oxides is the trend for the future development of high-efficiency adsorbents. The aim of this paper is to provide a theoretical reference for the in-depth study of the mechanism of mercaptan adsorption and the construction of new efficient mercaptan adsorbents.