Volume 22, Issue 11 - Special issue dedicated to the International Energy Conference (IEC 2023): Energy and Climate Change

This Special Issue of the International Journal of Chemical Reactor Engineering (IJCRE) presents selected manuscripts from the International Energy Conference 2023 (IEC 2023), which took place in Zacatecas, Mexico, from September 18 to 22, 2023. As a biennial event, the IEC fosters research and discussions on global energy challenges. The 2023 edition of the conference focused on the role of sustainable processes in addressing energy and climate change. Key topics included energy efficiency, life-cycle assessments, sustainability strategies, public policies, and energy awareness. Beyond these themes, the IEC 2023 provided a platform for knowledge exchange, critical discussions, and reflections on the influence of both fossil fuels and renewable energy sources on the global energy landscape.

Atrazine is a triazine organochlorine herbicide used commonly in some countries like Mexico, however it is hazardous for human, vegetable and animal life. Atrazine reaches groundwater drinking sources, causing serious illnesses in the population. Understanding the mineralized atrazine biodegradation process is a crucial issue in dealing with soils containing atrazine. Bioremediation of soil and water contamination involves a complex interplay between mass transport and biological processes. Soil adsorption, solubility, and interfacial transport limit the availability of contaminants to microorganisms. This review summarizes the recent studies about metabolic pathways and enzymes to degrade atrazine to carbon dioxide, ammonia, water and biomass carried out by some bacteria and fungi species. The biodegradation of atrazine was analyzed, considering the different metabolic pathways of bacteria and fungi. Biodegradation of atrazine by bacteria is well studied, but the fungal metabolism of this compound remains less clear. Some species of white-rot fungi can naturally biodegrade complex compounds, such as lignin, an aromatic polymer that is a major component of plant cell walls. The lignin has a polyphenolic structure that presents similarities with many aromatic pollutants and herbicides like atrazine. A deep understanding of the mechanisms involved is a successful tool for the design of new strategies for biodegrading. A comparison of the rates of degradation between physicochemical and biological processes is included, and some recommendations for the microorganism species and conditions.

The sustainable valorization of discarded resources remains a challenge, and their requirements are crucial for long-term development. In this sense, we characterize biofuels of the diesel range obtained with used vegetable oils subjected to hydrodeoxygenation with Ni supported on tire rubber carbon obtained by the pyrolysis of waste tires. Under optimal reaction conditions, the vegetable oil conversion was 81.2 % with a selectivity of 82.3 % to C 10 –C 18 alkanes, which is supported by the results of the catalyst characterization. A vertical direct injection engine was used to compare the behavior of the renewable biofuel and petroleum diesel blends. In comparison to petroleum diesel, the blends with renewable biofuel showed minimal power loss. In addition, the use of blends containing biofuels allowed a reduction of 25 % of CO and HC, as well as a decrease of 48 % is smoke compared to petroleum diesel, due to the fact that renewable biofuels improved evaporation after injection, reduced the density, and did not contain aromatic components.

In the context of thermochemical energy storage (TCES) for concentrating solar power (CSP) applications, metal carbonates’ reversible calcination and carbonation are gaining prominence, particularly in the SrCO 3 /SrO system. This system is notable for its high theoretical energy density of 10.61 GJ/m³ and operational temperatures up to 1,200 °C. However, like the CaCO 3 /CaO system, SrO experiences a significant drop in reactivity during cycling due to sintering and agglomeration of particles. In this work is proposed that the conversion effective will be improved by mixing the strontium carbonate with calcium carbonate. The best mix found was 80/20 SrCO 3 /CaCO 3 with the operating parameters of calcination-carbonation temperatures of 1,200 °C and 900 °C, respectively. This reaction has a notably better stable conversion rate than pure strontium carbonate. The study was carried out using thermogravimetry analysis. The mixture was subjected to 9 cycles, and for the ninth cycle, there was an effective conversion of 33.14 %, which, compared to pure SrCO 3 , was 2.33 %; that was improved noticeably during the carbonation process. There was an increase in the percentage effective conversion of 30.81 %. Volumetric energy density was reduced from 6.93 to 2.81 GJ/m 3 in the first and after nine cycles. The XRD analysis of the unprocessed mixture after 4 and 9 cycles showed no formation of new or secondary compounds, only the expected compounds: SrO, SrCO 3 , CaO, and CaCO 3 . This important change is explained during the carbonation looping because the CaO remains encapsulated in the SrCO 3 and does not react completely at 900 °C. As a hypothesis, this encapsulation delays the sintering of the SrCO 3 . Using a T carb  = 850 °C promotes the carbonation of CaO. By promoting CaO to react, the CaO encapsulated is released rapidly, and the material was sintering faster than the T carb  = 900 °C. Comparing the seventh cycle at a T carb  = 900 and 850 °C, it is observed that the effective conversion decreases from 0.4431 to 0.4202 and, in the same proportion, the volumetric energy density.

In the present work, the Fischer–Tropsch synthesis (FTS) is carried out through simulation. This reaction uses a gas mixture, called synthesis gas, composed of carbon monoxide rich in hydrogen (H 2 /CO > 2.5), to form medium and long chain hydrocarbons (C 5 + ). For the modeling of this system, a packed bed reactor with a cobalt-based catalyst has been considered, which promotes the polymerization of methylene species, selective to linear paraffins and 1-olefins. The objective of this work is evaluating the impact of operation variables, such as feed flows and temperature, coolant flow, system pressure, on the chain length distribution of the products. Current operating policies does not promote selectivity to the production of synthetic gasolines (C 5 –C 12 ), because of the drastic increase in the temperature inside the reactor as consequence of the high exothermicity of the reactions (ΔH = −170 kJ mol −1 ). It has been impossible to maintain these reactions within the appropriate temperature range (475–520 K) without the presence of an external agent that manages the available heat, for this project molten sales have been proposed as a cooling medium (KNO 3 –NaNO 3 ), based on its favorable heat transfer characteristics. By analyzing the system responses, the open loop model has allowed us to explore multiple hydrocarbon production scenarios, specifically highlighting the increasing of the yield of synthetic gasoline (48 wt%) in the products, from a defined molten salts (coolant) countercurrent flow range (7.05E-2 at 2.50E-1 m/h). It was noticed that this heat management allowed us to obtain a specific range of hydrocarbons, representing the opportunity to control the growth of the chain length. In conclusion, this analysis will lay the foundations for the design control policies, which help to increase current yields of synthetic gasoline, making it possible to achieve the desired quality for the immediate future.

In this article, state variable re-construction in continuous biodigester was investigated. We proposed a Robust Adaptive Observer to estimate biomass and substrate concentrations based on CO 2 and CH 4 measurement. The observer in question is a robust and adaptable model-based methodology, designed to accommodate uncertainties in model parameters, process variability, and in-line noisy measurements. The numerical results demonstrated superior performance of the Robust Adaptive Observer over traditional robust, reduced-order observers. Finally, observers were validated through a comparative analysis using Integral Absolute Error, Time-Weighted Absolute Error, and Integral Squared Error metrics. In this context, this study presents a novel alternative for advancing cutting-edge detection technologies and their integration into the monitoring of bioprocesses, aligning with the paradigms of Industry 5.0.

The amount of greenhouse gases has increased considerably in recent years. Additionally, the energy required by humanity for daily activities is also on the rise. The planet is facing one of its worst crises, characterized by the overexploitation of fossil fuels due to population growth. It is estimated that by 2050, the global population will exceed 9 billion inhabitants. Chemical looping combustion (CLC), offers a potential solution. This process involves usually two interconnected reactors, usually with a fluidized bed, where combustion takes place in an alternate way. In this process, the oxygen required for combustion is provided by a solid oxygen carrier, the capacity of this depends on the nature of the material and is crucial to define the most effective one by a comparative study. Moreover, methane emissions are a significant concern, as methane is a potent greenhouse gas with a 25 times greater impact on the atmosphere compared to carbon dioxide as greenhouse gases. To address this, methane reforming in chemical cycles, such as Steam Reforming Chemical Looping Combustion (SR-CLC) or chemical looping reforming (CLR), is proposed. Using a Gibbs reactor and oxygen carrier data reported in the literature, the analysis of NiWO 4 , FeMoO 4 , Fe 2 MnO 4 and FeZnO 4 , their operation, energy yield when exposed to a methane stream and the comparison between different forms of reforming schemes, as well as the estimation of the carrier needed for the process, are presented. Results indicate that after calculations, the g-carrier/g-fuel ratio for NiWO 4 is almost 100 % higher than the other carriers studied in this work. Water vapor reforming generates 30.0930 kW and a stream of pure hydrogen that can be separated while carbon dioxide reforming is a general endothermic process that requires 12.22 kW of energy for this process scheme. Once the ideal carrier has been analyzed, the proposed future work should focus on the optimal design of a reaction system that will allow it to operate efficiently under the conditions encountered. In addition, it will be necessary to find the replacement rate for the carrier that will allow us to operate our system continuously.

In this study, we investigated the performance of graphene oxide (GO)-based catalysts, including commercially available GO, GO synthesized via the All Kemie Sus method, and GO/TiO 2 composites, for CO 2 reduction under both UV and visible light irradiation. The catalysts were systematically characterized using XRD, SEM, FTIR, EDS, UV, and XPS techniques to elucidate their structural and chemical properties. Our findings reveal the remarkable versatility of these materials, demonstrating their ability to produce a diverse array of value-added products, including methane, ethane, formaldehyde, and methanol. Commercial GO achieved the highest ethane yield of 2.25 × 10 2  µmol and an initial reaction rate of 2.7 × 10 4   μ m o l g c a t h $\frac{\mu mol}{{g}_{cat}h}$ followed by GO/TiO 2 with a yield of 4.16 µmol an initial reaction rate of 4.99 × 10 2   μ m o l g c a t h $\frac{\mu mol}{{g}_{cat}h}$ . Notably, the GO/TiO 2 composite was only tested due to its promising potential for enhancing charge separation and catalytic efficiency, however, further studies are recommended. Moreover, the greener synthesis methods employed for GO All Kemie Sus highlight the importance of sustainable approaches in catalyst development. Overall, this study provides valuable insights into the performance and potential applications of GO-based catalysts for CO 2 photocatalytic reduction, laying the foundation for further advancements in this research area towards sustainable energy technologies and environmental conservation.

This work develops a 2D numerical simulation of a chemical looping combustion (CLC) system, which utilizes syngas (CO + H 2 ) as fuel and natural ilmenite as the oxygen carrier, with a particle diameter of 150 µm. The CLC process consists of two interconnected fluidized bed reactors: the “air reactor (AR),” where oxygen carrier oxidation reactions occur in the presence of air, and the “fuel reactor (FR),” where fuel combustion takes place using oxygen from the carrier, in the absence of air. The theoretical result is the complete combustion of the fuel, which occurs in two independent reactors that only communicate through interconnecting pipes transporting the oxygen carrier material; however, in practice, some studies show incomplete combustion of the fuel. The interest in understanding and modeling this process is based on its feasibility as an alternative to prevent the emission of CO 2 mixed with N 2 into the atmosphere, as occurs in conventional combustion. In this process, both gases are emitted in separate reactors; that is, CO 2 is released mixed only with water vapor, which can be easily condensed. This approach helps avoid the high costs associated with separating CO 2 from N 2 . Computational Fluid Dynamics (CFD) simulated the CLC system in a 2D domain. Using the Eulerian multiphase model, the behavior of oxygen carrier particles and the corresponding heterogeneous reactions were simulated in both the FR and the AR. The aim was to analyze the functioning and performance of the reactor, as well as the oxidation (combustion) of CO and H 2 . These results were validated with previously published data. The details of the particle motion reveal that the particles remain in a regime of bubble fluidization as the chemical reactions take place. The results also indicate that exploring new configurations, operating conditions, or boundary conditions in future studies to promote fuel oxidation and achieve complete combustion may be possible.

Photocatalytic properties of the magnetic fraction (MF) from a black sand sample, were evaluated to produce hydrogen by heterogeneous photocatalysis, using formic acid as hole scavenger. MF is mainly composed of ilmenite (FeTiO 3 ), hematite (α-Fe 2 O 3 ), maghemite (γ-Fe 2 O 3 ), and magnesioferrite (MgFe 2 O 4 ), as detected by X-ray analysis. MF particles are rugose with irregular morphology, smooth surface (without porous), and coarse surface. Also, Energy Dispersive X-ray Spectroscopy (EDS) microanalysis indicated the presence of major elements such as Fe, Ti, Si, Al, Mg, Ni, Cr, Ca, Na, K. MF sample absorbed from 200 to 2,500 nm wavelengths with several absorption edge energies due to indirect transitions and interactions, probably of FeTiO 3 and its interaction with the other semiconductors. The value obtained for the main absorption edge for Band gap (indirect transitions) of the MF was 3.5 eV. An experimental design (2 k ) was carried out to examine the influence of the initial concentration of formic acid (1–20 v/v %), the photocatalyst dose (0.1–1 g/L), and reaction time (2–8 h) on the amount of produced hydrogen and the residual Total Organic Carbon (TOC) content in the liquid phase. The greatest hydrogen production (150.97 μmol/L) was obtained using 20 % v/v formic acid and 1 g/L of photocatalyst after 8 h of irradiation.

Carbon dioxide (CO 2 ) is a major greenhouse gas produced by anthropogenic activities, such as industrial processes and energy consumption. This study focuses on CO 2 adsorption, a widely used industrial method, specifically dynamic CO 2 capture from the atmosphere using ammonia-modified granular activated carbon (OXA-GAC). The research integrates experimental investigations with mathematical modeling to optimize the adsorption process. A numerical solution for mass balance equations, formulated from partial differential equations (PDEs), was implemented using the method of lines (MOL). To simulate the CO 2 breakthrough profile in the adsorption column, three kinetic models were employed: pseudo-first-order, pseudo-second-order, and Avrami. Among these, the Avrami model demonstrated the best fit, exhibiting the highest correlation factor with experimental kinetic data at 30 °C, 45 °C, and 60 °C. Furthermore, two equilibrium adsorption isotherms, Toth and Langmuir, were evaluated. For low CO 2 concentrations, the Yoon-Nelson model outperformed the Thomas model, particularly at 30 °C and 45 °C across all C/C 0 ratios. At 60 °C, the adsorption performance in the column was accurately represented by these models for C/C 0 ratios below 0.7. This study contributes to the advancement of CO 2 capture technologies by optimizing dynamic CO 2 adsorption using OXA-GAC. It provides valuable insights into process optimization under varying temperature and concentration conditions, supporting the development of more efficient and sustainable carbon capture systems.