Asia-Pacific Journal of Chemical Engineering最新文献

The current investigation deals with improving the synthesis of cobalt-doped titanium dioxide (TiO₂) utilizing both ultrasound-assisted and conventional impregnation methods with an objective to obtain better catalyst characteristics. The impacts of process parameters such as sonication power, irradiation time, duty cycle and precursor doping on the catalyst characteristics have been analysed to optimize the catalyst characteristics including its particle size. Different characterization methods, including XRD, BET, TEM and FTIR have been used to compare the catalysts produced using both approaches under optimal conditions. Catalyst synthesized at 1 mol% doping, 90 min as irradiation time, 80 W as sonication power and 50% as duty cycle showed a minimum particle size of 231 nm and surface area of 9.2 m²/g. The catalyst obtained utilizing the ultrasound-assisted technique was obtained in significantly lesser time (90 min) compared to the catalyst obtained using the conventional approach (24 h). Photocatalytic oxidation tests carried out to determine the activity also showed that the Co-doped TiO₂ catalyst obtained ultrasonically showed maximum activity for degradation of Acid Violet 7 in conjunction with H₂O₂ at the optimal loading.

Liquid organic hydrogen carrier (LOHC) technology has unique advantages in hydrogen storage and transportation. However, the lack of research on the continuous dehydrogenation process of LOHCs has hindered the design and application of industrial dehydrogenation processes. In this work, a highly active dehydrogenation catalyst 1.5 wt% Pd/activated carbon (Pd/C) and a commercial catalyst 5 wt% Pd/Al₂O₃ were used for the continuous dehydrogenation of dodecahydro-N-ethylcarbazole (12H-NEC). Based on a tubular reactor and lab-scale apparatus, 1.5 wt% Pd/C catalyst achieved a maximum dehydrogenation conversion of 98.3% and a maximum NEC selectivity of 95.3%, while dehydrogenation conversion and NEC selectivity with 5 wt% Pd/Al₂O₃ were 98.3% and 97.6%, respectively. It showed the equally excellent performance between Pd/C and Pd/Al₂O₃, and the former has less Pd loading than the latter, with the potential of reducing the production cost of the dehydrogenation catalyst. The dehydrogenation results also indicated the difference in catalytic performance between the two kinds of catalysts. The obtained kinetics data were analyzed, and the dynamics of continuous dehydrogenation were studied to provide fundamental information for dehydrogenation scale-up.

The management and prevention of hydrates are crucial for the gas industry. This study delves into the intricate challenges associated with gas hydrate formation, with a specific focus on investigating the impact of corrosion by-products on prevention strategies. Employing a distinctive methodology, the sapphire pressure–volume temperature (PVT) cell was utilized. Experimental tests were conducted using sodium chloride (NaCl) concentrations of 1% and 3% to simulate brine solution levels at the wellhead, incorporating 3% filtrate and unfiltered iron carbonate (FeCO₃) as corrosion products associated with the production process. The 1% and 3% salt concentrations were chosen to encompass a broad range of temperature depressions, reflecting common industry standards for simulating realistic environmental conditions. PVT cell test conditions ranged from 80 to 200 bar, with increments of 40 bar. The experiments investigate the effects of common pipeline salts on a monoethylene glycol (MEG)/water mixture in the presence of methane gas at typical industry high-pressure conditions. The investigation uncovers that the introduction of salts to water, methane, and MEG solutions serves as a hydrate inhibitor, with inhibitory effects directly correlated to salt concentration. While generally hydrate growth inhibition is beneficial in natural gas pipelines, the findings indicate that elevated salt concentrations and lower pressure conditions contribute to the formation of larger hydrates, heightening the risk of surface adhesion and potentially introducing complications in piping equipment, despite the decreased temperature at which these hydrates form due to the inhibitory effects of the salts. In particular, the mixed condition of 3% NaCl and 3% FeCO₃ (filtered) has the strongest effect. Examination of hydrate formation temperature and macroscopic observations suggests that the existence of substantial precipitates, as evidenced in the unfiltered FeCO₃ sapphire cell experiment, may have the potential to enhance hydrate growth.

This research explored the characteristics of polymer composites reinforced with orange peel biochar. The composites were created using the hand lay-up method with different filler ratios, cured at ambient temperature, and analyzed with various analytical techniques, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and energy dispersive X-ray spectroscopy (EDX). SEM images showed that roughness increased with higher filler percentages. FTIR analysis detected functional groups like OH, COOH, and aromatic compounds in the composites, primarily inheriting these groups from the resin. Elemental analysis using EDX indicated that the composites contained carbon, oxygen, silicon, aluminum, and potassium. Among these elements, only the carbon concentration demonstrated a linear increase with rising filler levels, with the composite containing 40% biochar achieving the highest carbon content at 84%. Hardness testing showed that the physical strength of the composites increased as the polystyrene resin matrix was reinforced, with the 40% biochar composite exhibiting a maximum hardness value of 296 N. These results indicate that adding biochar not only enhanced the properties of polystyrene-based composites but also reduced their environmental impact.

In various industrial applications, especially within the internal pipes of heat exchanger devices, there is a crucial need for surface coatings that offer both superhydrophobic properties and high thermal conductivity. Achieving the balance between these two characteristics is essential for optimizing heat transfer performance along metal pipe walls and mitigating the formation of water droplets on the surface. This research focuses on the development of polymer composite coatings to address these dual requirements, providing protection against humid environments, resistance to dew formation, and simultaneous enhancement of thermal conductivity. The key challenge lies in selecting a coating type that provides low surface energy and polarity, thereby achieving the desired hydrophobic properties while also maintaining adequate thermal conductivity. This study formulates polymer composite coatings utilizing laser-modified epoxy resin and strategically integrates graphite oxide particles. These graphite particles undergo modification through oxidation to enhance compatibility with epoxy. In conjunction with graphite oxide modification, the resulting laser-modified coatings exhibit super-hydrophobic characteristics with an enhanced water contact angle of 162° and a low contact angle hysteresis (<5°). Furthermore, the epoxy/graphite oxide composite coatings demonstrate improved thermal conductivity, marking a significant 261% increase compared to pure epoxy, elevating it from .234 to .846 W/mK.

The practical application of traditional data-driven techniques for process monitoring encounters significant challenges due to the inherent nonlinear and dynamic nature of most industrial processes. Aiming at the problem of nonlinear dynamic process monitoring, a novel fault detection method based on dynamic kernel principal component analysis combined with weighted structural difference (DKPCA-WSD) is proposed in this paper. Initially, the proposed method leverages a sophisticated nonlinear transformation to project the augmented matrix of the original input data into a high-dimensional feature space, thereby facilitating the establishment of a DKPCA model. Subsequently, the WSD statistic is computed, utilizing a widely known sliding window technique, to quantify the mean and standard deviation differences across data structures. Ultimately, the WSD statistic is utilized for fault detection, completing the process monitoring task. By integrating the capability of DKPCA to capture nonlinear dynamic characteristics with the effectiveness of the WSD statistic in mitigating the impact of non-Gaussian data distributions, DKPCA-WSD significantly enhances the monitoring performance of traditional DKPCA in nonlinear dynamic processes. The proposed method is evaluated through a numerical case exhibiting nonlinear dynamic behaviors and a simulation model of a continuous stirred tank reactor. A comparative analysis with conventional methods, including principal component analysis (PCA), dynamic principal component analysis, KPCA, PCA similarity factor (SPCA), DKPCA, and moving window KPCA (MWKPCA), demonstrates that DKPCA-WSD outperforms traditional fault detection techniques in nonlinear dynamic processes, offering a substantial improvement in monitoring performance.

The problem of nitrogen oxide (NO_x) emissions has attracted wide attention in the field of environmental protection. The effects of sodium hydroxide (NaOH), hydrogen peroxide (H₂O₂), phenol (C₆H₅OH) and ethanol (C₂H₆OH) on the denitration activity of selective non-catalytic reduction (SNCR) and the emission of secondary pollutants nitrous oxide (N₂O) and carbon monoxide (CO) were investigated. Results indicated that the addition of NaOH, phenol and ethanol can improve the denitration efficiency under low temperature by providing OH. From 650°C to 750°C, ethanol had the best effect, with the denitration efficiency of 30%. From 750°C to 850°C, the denitration efficiency of phenol was 40% ~ 50%. The introduction of phenol and ethanol would increase the N₂O and CO emissions. From 700°C to 800°C, hydrogen peroxide only caused a small amount of N₂O emissions and had no significant effect on CO.

Computational fluid dynamics (CFD) is a powerful tool to provide information on detailed turbulent flow in unit processes. For that reason, this study intends to reveal the flow structures in the horizontal pipe and biomass combustor. The simulation was aided by ANSYS Fluent employing standard $�k$-$�\epsilon$ model. The results show that a greater Reynolds number generates more turbulence. The pressure drop inside the pipe is also found steeper for small pipe diameters following Fanning's correlation. The fully developed flow for the laminar regime is found in locations where the ratio of entrance length to pipe diameter complies with Hagen–Poiseuille's rule. The sucking phenomenon in jet flow is also similar to the working principle of ejector. For the biomass combustor, the average combustion temperature is 356–696°C, and the maximum flame temperature is 1587–1697°C. Subsequently, air initially flows through the burner area and then moves to the outlet when enters the combustor chamber. Not so for particle flow, the particle experiences sedimentation in the burner area and then falls as it enters the combustor chamber. This study also convinces that secondary air supply can produce more circulating effects in the combustor.

Rolling oil sludge (ROS) is a type of solid waste produced during steel rolling; this waste contains not only a high iron content but also many harmful organic components and is a very attractive secondary resource. This paper introduces the sources and hazards of ROS, summarizes the recycling methods integrated with steel production, classifies traditional treatment technologies, and analyzes their advantages and disadvantages. Combined treatment is the main direction of ROS treatment methods in the future. The ROS recycling techniques applied in different industries are summarized. Finally, existing problems and future work are described to promote the remediation and resource utilization of ROS.

Feed spacers improve mixing and mass transfer in membrane modules. However, they also lead to foulant deposition in the vicinity of the spacer surface. In this paper, two hydrophilic monomers, namely, acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA), are respectively coated on the surface of a commercial feed spacer via a plasma-enhanced chemical vapor deposition (PECVD) method. The resulting modified spacers are then evaluated alongside with a reverse osmosis (RO) membrane for its solute rejection, water permeability, and antifouling properties. Results show that the surface hydrophilicity of feed spacers has been enhanced upon the AA and HEMA deposition. During filtration test, the HEMA-modified spacer demonstrates higher flux recovery rate (94.17%) and salt rejection (95.78%) for the RO membrane. In contrast, the membrane with the unmodified spacer only shows 89.44% and 92.46%, respectively. Additionally, the membrane with the HEMA-modified spacer has a thinner fouling layer (200 nm) compared to the unmodified spacer (700 nm). The HEMA-coated spacer outperforms all the tested spacers, demonstrating that feed spacer modification with a hydrophilic monomer via the PECVD method can effectively reduce membrane fouling.