Engineering Chemistry Vol. 13

Abstract: CO₂ conversion to methanol via thermocatalytic hydrogenation is one of the viable alternatives to address climate change problem while producing a valuable industrial product. However, this comes with a challenge, i.e., predicting the performance of catalytic systems. In this work, we present a data-driven study to predict the performance of Cu-based catalyst based on a compiled dataset consisting of 15 features obtained from experiment data. Furthermore, we implement feature selection techniques such as univariate, RFE, and XGBoost to investigate how the performance of the prediction model changes with varied number of features. The results show that features selected by RFE method yields the best performance with 7 number of features, capable of even outperforms the baseline model in terms of accuracy and feasibilty. This suggests that feature selection technique is relevant in terms of constructing a machine learning model for predicting methanol production via CO₂ thermocatalytic hydrogenation.

Abstract: A promising approach to meet rising energy demands while mitigating environmental risks from greenhouse gases is the conversion of carbon dioxide into methanol through CO₂ hydrogenation. Previous studies have demonstrated that unsupported subnanometer Pd_x clusters exhibit excellent performance in this conversion. However, the influence of support materials on the activity of Pd clusters remains poorly understood. In this study, we compare the kinetics of CO₂ hydrogenation to methanol using unsupported Pd₇ clusters and those supported by metal oxides, specifically Pd₄/In₂O₃(110) and Pd₃/TiO₂(110). Microkinetic simulations, based on available energetic data from the literatures, reveal that Pd₄/In₂O₃(110) delivers superior kinetic performance, followed by Pd₇ and Pd₃/TiO₂(110). These findings demonstrate that the choice of support material plays a critical role in dictating the reaction pathway and rate for supported Pd cluster catalysts.

Abstract: The current study was carried out to measure the heat resulting from the spontaneous dissociation of some inorganic salts by using sodium chlorate and ammonium perchlorate salts (3gm), iron filings (22gm) with grain size (350 µ), sawdust (7gm) with a size of (200 µ), activated carbon (7gm), and distilled water (8ml), The speed of the reaction was measured and found it was second degree (n=2). Measurement of the heat of the reaction emitted was also studied in several ways, including the direct method from the Vant-Hoff equation and the calorimetric method, in addition to comparing it with the theoretical value of standard heat of formation which showed the dependence of the reaction temperature on the two salts. Moreover, classical methods were used to determine the amount of chlorate and perchlorate radicals by depositional gravimetric analysis and volatilization methods.

Abstract: The study involves treating various metal complexes in "gas phase" with the prepared ligands (2,6-bis (((1-octyl-1H-1,2,3-triazol-4-yl) methoxy) methyl) pyridine (L₁), 2,6-bis (((1-decyl-1H-1,2,3-triazol-4-yl) methoxy) methyl) pyridine (L₂) and 2,6-bis (((1-dodecyl-1H-1,2,3-triazol-4-yl) methoxy) methyl) pyridine (L₃). Two different types of programs, the Hyperchem-8 and Gaussian programs, were used to study the theory. The heat of formation (ΔH^of), binding energy (ΔEb), and dipole moment (µ) for free ligands and some metal complexes were calculated using semi-experimental and molecular mechanics in the Hyper-8 program using a variety of computational techniques including ZINDO/1, PM3, and AMBER methods at room temperature. The created complexes are discovered to be more stable than the free ligands. For proper location of the molecules, Hyperchem.-8 was used to determine the vibration frequencies for (FT-IR) and electronic transitions, as well as electrostatic potential, HOMO, and LUMO energy. The compatibility of the theoretical and experimental findings was highlighted. In order to calculate the geometry optimization, dipole moment (µ), total energy, electrostatic potential, LUMO, and HOMO, a Gaussian algorithm employing a semi-empirical (PM3) approach was utilized. "Vibration spectra of free ligands are calculated and noted that they agreed well with those values experimentally found" diagnosis with a higher level of capacity to effectively diagnose packages. Using a technique like ZINDO/S, the electronic transitions for the ligand were also computed.

Abstract: This work reports the structural and humidity-sensing properties of Tin (Sn)-doped Zinc Oxide (ZnO) nanostructures deposited on Aluminum-doped Zinc Oxide/Polyethylene Terephthalate (AZO/PET) substrates via the sol-gel immersion method. Accordingly, X-ray Diffraction (XRD) and FESEM analyses confirmed that low-level Sn incorporation (1 at.%) enhanced the (002) orientation and crystallinity, while higher doping introduced lattice distortion and defects. Meanwhile, humidity sensing measurements revealed that undoped ZnO exhibited the highest sensitivity (178.5), though it recorded a very slow response (231 s) and recovery (648 s). In contrast, 1 at.% Sn-doped ZnO achieved a balanced performance, combining high sensitivity (144.4) with much faster response (121 s) and recovery (411 s). These results demonstrate that controlled Sn doping optimizes ZnO nanostructures for flexible humidity-sensing applications. Overall, the findings provide valuable insight for developing real-time environmental and wearable sensing devices, with future work focusing on stability testing and mechanical flexibility evaluation.

Abstract: Essential oils are volatile bioactive compounds widely used in pharmaceuticals, food preservation, cosmetics, and aromatherapy. Conventional hydrodistillation and steam distillation remain the primary recovery methods but suffer from long extraction times, moderate yields, and thermal degradation. Mechanical and physicochemical pretreatments address these limits by disrupting secretory structures, shortening diffusion paths, and enhancing mass transfer. From a chemical engineering perspective, this review synthesizes evidence published between 2010 and 2025 on particle-size reduction, ultrasound-assisted hydrodistillation, microwave-assisted hydrodistillation, steam explosion, instant controlled pressure drop, and cold pressing of citrus peels. Outcomes vary by matrix: in seeds such as celery, ultrasound-assisted hydrodistillation increases yield by nearly 50% compared with conventional hydrodistillation; in citrus peels, steam explosion accelerates extraction up to eightfold but reduces composition to limonene, while cold pressing preserves thermolabile aldehydes and esters crucial for fragrance. Instant controlled pressure drop applied to hyssop and Tagetes enhances yield, accelerates kinetics, and improves antioxidant indices through microstructural expansion confirmed by microscopy. In leaves and flowers including rosemary and lavandin, ultrasound- and microwave-based methods consistently shorten cycles while maintaining comparable chemical and sensory profiles. The addition of low-cost modifiers such as sodium chloride and optimized water-to-solid ratios further improves rosemary hydrodistillation without compromising oil quality. These findings highlight trade-offs among rate, yield, and composition. Standardized reporting of particle size, moisture content, and kinetic parameters is recommended to ensure reproducibility and cross-study comparison. Mechanical pretreatments thus provide a flexible framework to optimize essential oil extraction across industrial and bioengineering applications.

Abstract: Palm Kernell Shell (PKS), a form of biomass waste can be transformed into higher-value products. In this study, PKS underwent pyrolysis process at various temperatures using a macro-thermogravimetry fixed-bed reactor. The research focuses on biochar production through slow pyrolysis and assesses the life cycle impact of biochar as a substitute for commercial fertilizer. The aim is to assess the effect of temperature variation on biochar properties and compare greenhouse gas (GHG) emissions between biochar-based and conventional fertilizers. The OpenLCA software was employed to conduct the life cycle assessment (LCA). The optimal temperature for biochar production through a slow pyrolysis process was identified as 450°C, yielding a carbon-to-nitrogen (C/N) ratio of 19.4. The study also investigated GHG emissions throughout the PKS lifecycle, involving oil palm cultivation, crude palm oil (CPO) milling, and biochar production through slow pyrolysis (cradle-to-gate). Substituting commercial NPK fertilizers with biochar in oil palm cultivation demonstrated significant reduction in GHG-related impacts, including global warming potential, acidification, eutrophication, and ecotoxicity by 3.6%, 20.7%, 10.7%, and 2.7% respectively.

Abstract: Co-firing Refuse Derived Fuel (RDF) from Municipal Solid Waste (MSW) with coal presents a promising approach to urban waste management and reduction of fossil fuel dependency. This study primarily investigates the optimal co-firing ratio of RDF MSW and coal, alongside other operational parameters, in a laboratory-scale fluidized bed reactor. Experiments were conducted with variations in RDF MSW to coal ratio (5%, 10%, 15%), operating temperature (750°C, 850°C, 950°C), and excess air (15%, 20%, 25%, 30%) in a reactor with a combustion chamber volume of 1000 cm³. Results demonstrate that the co-firing ratio significantly influences combustion efficiency and overall performance. The optimal ratio was found to be 10% RDF MSW with 90% coal, yielding a peak combustion efficiency of 95.89% and a minimum Specific Fuel Consumption (SFC) of 0.19260 kg/kWh. This optimal ratio balances the benefits of RDF's higher volatile content with coal's stable combustion characteristics. Additionally, an operating temperature of 750°C and excess air of 20% complemented this optimal ratio, further enhancing stability and efficiency. SEM analysis and chemical composition studies of agglomerates revealed the role of Ca, K, Na, and Mg in deposit formation, providing insights into the interaction between RDF and coal during co-firing. This research offers valuable guidance for optimizing co-firing ratios in industrial applications, supporting the development of more efficient and environmentally friendly waste-to-energy solutions.

Abstract: This research discusses the biomass gasification process for hydrogen production, integrated with a carbon capture process for product purification. A new simulation model was developed in Aspen Plus, incorporating a gasifier, a water–gas shift (WGS) reactor, and a carbon capture unit. Oil palm empty fruit bunches were selected as the biomass feedstock. The simulation investigated the effects of different gasification agents (O₂, air, and steam) and gasifier operating temperatures on hydrogen yield. It also evaluated the influence of MDEA solvent flow rate on CO₂ capture efficiency. Results showed that using a mixture of O₂ and steam with a ratio of 0.5 at 800 °C produced favorable outcomes, with negligible impurities. The addition of steam in the WGS reactor enhanced hydrogen production, with the highest yield achieved at a steam ratio of 0.6. A 2:1 molar ratio of MDEA to CO₂ resulted in up to 99.9% carbon dioxide removal.

Abstract: Given the importance of enhance the performance of oil separators in production field, this research study the separation process through simulations based on a real field data, WQ-2 south of Iraq-Basra. By implementing both dynamic and steady-state approaches in Aspen HYSYS V.14, the optimization was carried out for each approach for comparison. Results from the steady-state simulation revealed limited improvement, with closely converging iterations and changes applied to only one variable at a time. In contrast, the dynamic simulation given more realistic and favorable results, as manual adjustments were applied in a real-time response to the actual field dynamics range and conditions. The result shows that the maximum OVFR=15050 m³/h and CO=0.1999099 at T= 60 °C and P= 15 barg for static model, while the OVFR=1580.9 m³/h, CO=0.0093 at P=14 barg, T=76 °C where the operation time 120 min for dynamic. Compared to the static approach, the dynamic approach was efficient to reach better performance when the selected parameters were optimized and that led to a substantial improvement in the separation efficiency. Therefore, the dynamic simulation could be considered a mandatory approach when the overall separator efficiency need to be enhanced.