Journal of the Taiwan Institute of Chemical Engineers最新文献

1) Background

2,6-xylenol and p-cresol are widely used in medicine synthesis, which are both important raw materials in chemical engineering. It is shown significant economic benefits to separate 2,6-xylenol and p-cresol. Owing to the extremely relative volatility between 2,6-xylenol and p-cresol, it is difficult to separate the two phenolic compounds through conventional distillation.

2) Methods

The results of vapor–liquid equilibrium analysis, COSMO-SAC and reduced density gradient result are used to investigate molecular interaction in the separation system, indicating diethylene glycol (DEG) as the optimal solvent. Accordingly, we propose an energy-saving extractive distillation process with DEG as an efficient entrainer for the separation of 2,6-xylenol and p-cresol. Total annual cost (TAC) and CO₂ emission are investigated for optimization and estimation of the proposed process. In addition, three energy-saving scenarios for further reductions in TAC and CO₂ emission are proposed.

3) Significant Findings

Compared with the benchmark process, the TAC and CO₂ emission of the energy-saving design vapor recompression heat pump assisted extractive distillation separation sequence B are reduced by 26.18 % and 49.18 %, respectively, which indicates that the considerable industrial potential of the proposed design.

Backgrounds

Bamboo leaves ash (BLA) is a cheap and sustainable silica source but under-utilized. In this work, mordenite zeolites with various morphologies synthesized from BLA are reported.

Methodology

Our strategy involves merely mixing of silicate and aluminate solutions where parametric crystallization study successfully captured three mordenite synthesis recipes. The prepared solids are then characterized with XRD, SEM, XRF, FTIR, TGA/DTG, N₂ sorption and TPD-NH₃ before their catalytic behavior is tested in acetalization .

Significant findings

Mordenites with three distinct shapes (nanostick, intergrown bulky ball, nanorod) are successfully synthesized via parametric crystallization study. Some mordenite zeolites contain hierarchical micro/mesoporosity which is beneficial in acetalization of benzaldehye and glycerol. The nanorod-like mordenite is the best catalyst (80.2 ± 2.4 % conversion, 54.4 ± 0.3 % selective towards 2-benzyl-4-hydroxymethyl-1,3-dioxolane) and its catalytic performance is better than those of classical homogeneous and zeolite catalysts with high recyclability.

Background

The treatment of dye residue water pollution is a hot research topic, so it is necessary to prepare a resin which can adsorb dye efficiently.

Methods

The sodium polystyrene sulfonate (PSSNa) were prepared by the sulfonation reaction of styrene resins with concentrated sulfuric acid and applied for Methylene Blue adsorption in wastewater. The structure of PSSNa was characterized by FT-IR, SEM, XPS and XRD.

Significant findings

The results show that the maximum adsorption capacity is 16.89 mg∙g⁻¹. The adsorption processes of Methylene Blue with PSSNa conforms to the pseudo-second-order kinetic model and the Langmuir isotherm adsorption model, which means that the adsorption process follows single-molecular layer adsorption mechanism. The characteristic group (–SO₃⁻) of the exchange resin interacts electrostatic with MB. Good desorption was achieved with 1 mol·L⁻¹ HCl solution, and the resin retained good adsorption capacity after 5 adsorption-desorption cycles. In practical applications, PSSNa exhibits a good removal efficiency for dyes containing MB in lake water. These results provide a reference for the treatment of printing and dyeing wastewater by resin adsorption materials.

Background

Direct production of light olefins (basic chemical raw materials in the industrials) from syngas using promoted catalysts demonstrates great potential, because of their upgraded performances.

Methods

In this study, a series of Fe-based catalysts promoted by Mn and Zr were prepared by hydrothermal and microemulsion methods and applied to the Fischer-Tropsch reaction. To optimize the catalysts, response surface methodology combined with the central composite design was applied to three independent parameters of the synthesis method, weight percent of Zr promoter (2th promoter) and reaction temperature. To clarify the relationship between the synthesis methods, the synergistic effect of Zr and Mn promoters, and catalyst performance, in detail, different characterization analyses were studied, including XRD, BET, SEM-EDS, FESEM, TEM, H₂-TPR, and CO-TPR.

Significant findings

According to developed statistical equations, it was revealed that the synthesis method is the most influential parameter on CO% and O/P ratio. The experimental results indicated that Zr and Mn promoters had a negative synergistic effect on the CO% and O/P, but a positive one on the heavy hydrocarbons selectivities. The characterization results demonstrated that hydrothermal prepared FeMn catalyst, due to having uniform particle size distribution, cubic morphology, and better reduction at low temperature had highest CO%.

Background

The mechanics of blood flow via converging diverging conduits is an intriguing phenomenon that involves multiple fundamental principles of fluid dynamics. Blood arteries can diverge, which means they expand, or converge, which means they contract down. This specific structure is essential for controlling blood flow and preserving adequate circulation across the body. The theory of fluid mechanics is significant concept related to blood flow along converging/divergent channels. Elevated shear strains near the narrower artery throat can stimulate platelets, causing thrombosis that can completely or partially stop blood supply to the human brain or heart. This communication addresses the blood flow in convergent and diverging artery using fundamental concept of fluid mechanics. The Prandtl fluid model is considered as a blood, because of its viscoelastic nature. The influence of heat source, frictional dissipations and a chemical reaction are included.

Methods

The Jaffrey-Hamel flow in a converging and diverging conduits is generalized to Prandtl fluid model considering the purely radial flow through cylindrical pipe like artery with an arbitrary cross section. The governing equations are solved computationally using the Runge–Kutta-Fehlberg (RKF-4) method.

Significant finding

The rheological parameters ε and δ of blood show opposite tendencies for blood circulation. The Brownian and thermophoresis parameters has a significant effect on heat and mass transport rate. The presence of slip (semi blockage) produces flow reversal and higher drag forces at the arterial wall. Significant flow dynamics and heat-mass transport was reveled for diverging (wider) artery β > 0. The non-uniform heat source show similar trends for thermal profile and heat transfer rate.

Background

The depletion of fossil fuel supplies, along with ever-increasing energy needs, mandates the investigation of clean and renewable fuels. In this regard, the present investigation pursued to assess the suitability of response surface methodology (RSM) and machine learning strategy for optimising the process parameters of potato stalk (PS) pyrolysis.

Methods

The experiment was performed in a tubular reactor, and key process factors for example temperature (400 – 650°C), heating rate (50 – 100°C/min), and N₂ flow rate (150 – 200 ml/min) were optimised for maximum bio-oil yield. The key features of the produced liquid product (bio-oil) and solid product (biochar) were investigated.

Significant Findings

The PS physicochemical study demonstrated enormous bioenergy potential, with higher carbon content (45.82 %), calorific value (17.6 MJ/Kg), and lower moisture content (7.2 wt. %). The coefficient of variation for bio-oil biochar was 1.78 and 1.91 % (less than 10 %), indicating that the model is more reliable and reproducible. The artificial neural network (ANN) better forecasted the process yield; nevertheless, the RSM model successfully forecasted the pyrolysis factors interface and importance. The GCMS analysis of the bio-oil revealed 33.42 % hydrocarbons, 13.42 % esters, 4.62 % acids, 1.71 % ethers, 11.1 % ketones, 14.01 % alcohols, 2.34 % amides, 4.96 % nitrogen-containing substances, and 7.12 % phenols.

Background

Novel three-dimensional (3D) hydrated ceria-BTC (CeO₂–1,3,5-Benzenetricarboxylic-acid) is the important material due to its unique chemical and physical properties compared to the other materials. A novel 3D ceria nanostructure has been examined as a promising and feasible technique for methanol decomposition.

Methods

Novel 3D hydrated ceria-BTC microstructures were successfully synthesized via a hydrothermal route in an aqueous solution. Field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD) patterns show that a ceria-BTC framework diameter and length are approximately 1.45–2.4 and 5.5–6.5 µm, respectively, at 130 °C and with pH 2 for 72 h. The hexagonal ceria-BTC microrod comprises organic linkers, which are transformed into hierarchical ceria microrod in the presences of air at 400 °C was confirmed by Fourier transform infrared spectroscopy (FTIR).

Significant Findings

The Ce-O bonding of the hierarchical ceria microrod species has a bond distance and coordination number of 2.44 and 6.89, respectively, which attenuates the Extended X-ray absorption fine structure (EXAFS) spectra. Compared to the ceria powder, the hierarchical ceria microrods produced more oxygen vacancies and Ce³⁺as shown by the X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) analyses. The ceria microstructure exhibits excellent methanol decomposition activity.

Background

Securing critical metals is crucial for the transition from fossil fuels to renewable energies. In this regard, extracting metals from various sources and low-grade ores can lead to the sustainable production of metals. Manganese, as a strategic metal, can play a significant role in achieving this goal.

Methods

In this study, various reductants such as oxalic acid, citric acid, ascorbic acid, acetic acid, tannic acid, hydrogen peroxide, iron (II) sulfate, sodium thiosulfate, and DL-malic acid were used to evaluate the feasibility and comparison on the manganiferous iron ore leaching.

Significant findings

DL-malic acid was chosen as the main reductant to investigate other factors because it is novel (as a reductant), eco-friendly, cost-effective, accessible, and easily storable. Therefore, more detailed studies on the dissolution of manganiferous iron ore in the presence of DL-malic acid as the reductant were carried out considering different levels of temperature, particle size, acid concentrations, and leaching time. Increasing the temperature from 298 K to 348 K notably boosted the leaching recovery from 27.00 % to 70.11 %. It was observed that decreasing the ore particle size from -212 μm to -38 μm resulted in an enhancement of leaching recovery from 57.74 % to 70.11 %. Also, adding only 250 % stoichiometry of DL-malic acid notably increased the leaching recovery to 70.11 %, compared to just 5.32 % in a reductant-free medium. It should be noted that the concentration of sulfuric acid had a direct impact on leaching recovery, increasing by 28.28 % with a concentration of 0.5 M and by 93.08 % with a concentration of 4 M. In this research work, the kinetic of the leaching process was modeled using the modified shrinking core model (MSCM). The calculated activation energy was about 33 kJ/mole, which confirmed that the mixed mechanism controlled the reaction. Mn₃O₄ nanoparticles were synthesized using a pregnant leach solution (PLS) and through a multi-stage co-precipitation method. In this method, hydrogen peroxide was used to modify the manganese hydroxide phase as a more eco-friendly method than other heat treatment methods. The SEM and EDX analyses revealed an average particle size of 80 nm with spherical shapes and no impurities. The XRD pattern of the synthesized nanoparticles confirmed the Mn₃O₄ phase composition.

Background

Pollutants emitted from fuel combustion have become a global concern, prompting researchers to explore solutions like fuel formulation modification.

Methods

This study delved into enhancing gasoline fuel performance and octane number by incorporating varying proportions of 2-methyl-1-propanol, bioethanol, MTBE additives, tert‑butanol, and nanoparticles (ZnO, ZrO₂, and CNT). These compositions underwent assessment at different engine loads and speeds. Vapor pressure, a fundamental property of gasoline that signifies its volatility, was examined. Despite the utilization of diverse additives and enhancers, their impact on vapor pressure was minimal at relatively low concentrations.

Significant findings

As a result, flash point, octane number, and engine performance were evaluated for the developed fuels. The findings unveiled improved engine performance coupled with reduced emissions. The octane number demonstrated enhancement, approaching gasoline's, while the combustion point remained similar. Notably, pollutant levels exhibited significant reduction.

When comparing gasoline fuel at an engine speed of 1500 RPM and a throttle opening of 30 % with gasoline mixed with 2-methyl-1-propanol alcohol, MTBE, and zirconium dioxide under identical conditions, the results showed a reduction of 82.8 % in carbon monoxide emissions, carbon dioxide decreased by 54.05 %, unburnt hydrocarbons decreased approximately by 42.42 %, nitrogen oxides reduced by 22.97 %, engine power increased by 0.5 %, torque increased up to 164 %, and the octane number increased by 7.03 %.