Catalytic Conversion Research Articles

Process simulation, optimization, and cost analysis of a proposed sulfur recovery unit by applying modified Claus technology

Removing sour gas from any suitable gas sweetening technology in a cost-effective and environmentally responsible manner is a major challenge. This paper discusses how to safely and economically dispose of small amounts of acid gases resulting from the amine sweetening process. A two-stage Claus desulfurization unit was studied and simulated to treat acid gases resulting from natural gas sweetening operations in Ras Gharib oil fields (Egypt). These acid gases are used as feedstock for the proposed plant to produce a valuable product, such as elemental sulfur, which is used as a raw material in many industries. Although many sulfur recovery techniques are available for various conditions and applications, the Claus process is a critical and widely used method for recovering elemental sulfur from gaseous hydrogen sulfide. This work represents the potential benefits of treating acid gases with high hydrogen sulfide content. In addition, operational variables that could affect sulfur production and sulfur recovery efficiency of the studied Claus unit were studied and optimized. Aspen HYSYS simulation software (version 9) was used to evaluate the economic aspects and optimize the operational parameters of the unit for producing sulfur from acid background gases. The results showed that the maximum sulfur production was achieved at a catalytic converter reactor temperature of 270 °C and 210 °C for the first and second catalytic reactor, respectively, with an air flow rate of 933.3 kg mol/h. The economic study of the proposed desulfurization unit showed that the Claus unit would be economically acceptable with an expected return on investment of approximately 10% and an average payback period of 10 years. Moreover, the introduced plant has a positive impact on the environment by reducing the concentration of hydrogen sulfide in the gas from 69.58 to 0.16%.

Selective Photoreforming of Waste Plastics into Diesel Olefins via Single Reactive Oxygen Species.

The accumulation of plastic waste poses a pressing environmental challenge. Catalytic conversion stands out as an ideal approach for plastics upcycling, particularly through solar-driven plastics photoreforming. However, due to the common effects of multiple reactive oxygen species (ROS), selectively generating high-value chemicals becomes challenging.In this study, we developed a universal strategy to achieve >85% selective production of diesel olefins (C15-C28) from polyolefin waste plasticsviasingle ROS.Using tetrakis (4-carboxyphenyl) porphyrin supramolecular (TCPP) with different central metals as an example to regulate single ROS generation, results show Ni-TCPP facilitates triplet exciton production, yielding1O2, while Zn-TCPP generates •O2-due to its strong built-in electric field (IEF).1O2directly dechlorinates polyvinyl chloride (PVC) due to the electro-negativity of chlorine atoms and the low dissociation energy of C-Cl bonds, while •O2-promotes direct dehydrogenation of polyethylene (PE) due to the electro-positivity of hydrogen atoms and the high dissociation energy of C-H bonds. This method is universally applicable to various single ROS systems.Installationexperiments further affirm the application potential, achieving the highest diesel olefin production of 76.1 μmol·h-1. Such a universally adaptive approach holds promise for addressing the global plastic pollution problem.

Catalytic converter theft: An examination of the elasticity of crime

Catalytic converter theft: An examination of the elasticity of crime

Structural basis of chorismate isomerization by Arabidopsis ISOCHORISMATE SYNTHASE1.

Salicylic acid (SA) plays a crucial role in plant defense against biotrophic and semi-biotrophic pathogens. In Arabidopsis (Arabidopsis thaliana), isochorismate synthase 1 (AtICS1) is a key enzyme for the pathogen-induced biosynthesis of SA via catalytic conversion of chorismate into isochorismate, an essential precursor for SA synthesis. Despite the extensive knowledge of ICS1-related menaquinone, siderophore, tryptophan (MST) enzymes in bacteria, the structural mechanisms for substrate binding and catalysis in plant isochorismate synthase (ICS) enzymes are unknown. This study reveals that plant ICS enzymes catalyze the isomerization of chorismate through a magnesium-dependent mechanism, with AtICS1 exhibiting the most substantial catalytic activity. Additionally, we present high-resolution crystal structures of apo AtICS1 and its complex with chorismate, offering detailed insights into the mechanisms of substrate recognition and catalysis. Importantly, our investigation indicates the existence of a potential substrate entrance channel and a gating mechanism regulating substrate into the catalytic site. Structural comparisons of AtICS1 with MST enzymes suggest a shared structural framework with conserved gating and catalytic mechanisms. This work provides valuable insights into the structural and regulatory mechanisms governing substrate delivery and catalysis in AtICS1, as well as other plant ICS enzymes.

Integrated and Automated: Liquid Metal‐based System for Full Cycle CO2‐to‐Carbon Conversion

AbstractThe urgency for carbon neutrality is driving the need for cost‐effective Carbon Capture and Conversion (iCCC) technology, but the lack of a unified platform for capture, release, and the subsequent in situ catalytic conversion has hindered its widespread adoption. To address this gap, it have showcased the feasibility of achieving an energetically balanced design intertwining CO2 capture and in situ conversion through a continuous gas‐to‐solid reaction process on the customized liquid metal‐based reaction system. The system exhibits a remarkable carbon production capability, achieving a peak yield of 550.57 µmolC mmol CO2‐−1 accompanied by 100% carbon conversion rate. The vertically bottom‐up spiral reactor design introduces significant mass transfer enhancements, resulting in a higher conversion yield rate of 8658.3 µmol h−1 (323.24 µmolC mmolCO2‐−1) while requiring an energy input of only 30.79 GJ t−1 CO2 in a 1.508×10−3 m3 unit. The solid carbon produced in the continuous setup also holds the potential for high‐end application value, such as being a high‐performance material for wave adsorption or acting as an efficient photocatalyst. This research insights are poised to chart new pathway into refining the design strategy for CO2 solidification processes, particularly the seamless melding of carbon capture and in situ conversion.

Abstract PO2-18-08: Identification of novel genetic/therapeutic vulnerabilities in breast cancer

Abstract Background: Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer death among women worldwide. Triple negative breast cancer (TNBC) is an aggressive subtype that is defined by the lack of expression of estrogen and progesterone receptors in the absence of HER2 amplification or overexpression. TNBC represents 15-20% of all breast cancers and occurs more frequently in young premenopausal women. TNBC often ends with a poor clinical outcome due to high histological grade, rapid recurrence in many patients combined with few treatment options. These realities highlight the urgent need to identify novel therapeutics vulnerabilities that can be leveraged to improve TNBC patient outcomes. Methods: We utilized the publicly available DepMap and Kaplan Meier datasets to identify essential genes that were unique to TNBC cells and whose expression levels were associated with worse patient outcomes. siRNA based approaches were used to confirm the relevance of top hits in mediating cancer cell phenotypes including viability, cell-cycle profiles and induction of apoptosis among others. A novel drug currently being developed was identified for the top hit in these studies and was subsequently employed in multiple in vitro approaches to characterize the mechanisms of action in TNBC as well as initial efficacy studies using clinically relevant ex vivo patient derived models. Results: Using the DepMap database, we interrogated genome-wide sgRNA knockout screens conducted in over 40 breast cancer cell lines to identify specific genes whose expression was required for cell viability in TNBC cells, but not other breast cancer cell lines. This endeavor identified 6 genes (CTPS1, HUS1, PRKRA, RAD1, RAD9A and RHOA) that were preferentially essential in TNBC cells. Further profiling of these genes revealed that CTPS1 expression is higher in cancer relative to normal tissue and that its expression is further upregulated in chemotherapy- and PARPi-resistant models. Knockdown of CTPS1 in TNBC cells was shown to decrease cell proliferation and viability with no effects observed in estrogen receptor+ cell lines. Using a first-in-class, highly selective and orally bioavailable CTPS1 inhibitor (STP938) developed by Step-Pharma, we identified IC50s in the low nM range for many TNBC cell lines, including cell models that are resistant to existing standard-of-care therapies. Inhibition of CTPS1 was shown to arrest cells in S phase. Conclusions: Our studies have identified CTPS1 as an essential gene in TNBC. CTPS1 encodes an enzyme responsible for the catalytic conversion of UTP (uridine triphosphate) to CTP (cytidine triphosphate), an essential step in the biosynthesis of nucleic acids. These findings are timely in light of the recent and ongoing development of the first-in-class CTPS1 inhibitor, STP938, for which first-in-human studies are underway for refractory B- and T-cell lymphomas. Based on our initial studies using this drug, we provide pre-clinical evidence of its efficacy in multiple models of primary and advanced TNBC. Efforts are currently underway to move this work toward a clinical trial for TNBC patients. Citation Format: Xiyin Wang, Michael Emch, Lauren Voll, Rebecca Russell, Esther Rodman, Philip Beer, John Hawse. Identification of novel genetic/therapeutic vulnerabilities in breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-18-08.

Contrasting platinum trajectories in three major French rivers using dated sediment cores (1910–2021): From geochemical baseline to emerging source signals

Platinum (Pt) is a Technology Critical Element (TCE) which, since the 1990s, has been mainly used in the industry in catalytic converters for automobile emission control. Previous studies have shown Pt contamination of road-side sediments and surface sediments in urban rivers and lakes but few of them have addressed temporal variations. The present work presents historical Pt concentration trends in 137Cs-dated sediment cores from floodplains or secondary channels at the outlets of three major French watersheds (Loire, Rhone, and Seine Rivers) covering the past ~110 years, i.e., from the 1910s to 2021. Platinum baseline levels in the sediment were estimated for the Loire River (0.76 ± 0.22 μg kg−1 for the period ~1910-~1955) and the Rhone River (1.64 ± 0.41 μg kg−1), and historical Pt variations seem to reflect variations in hydrodynamics and grain size composition. Since the early 2000s, Pt concentrations in the Loire and the Rhone River sediments tend to increase (>2.5 μg kg−1) and were attributed to the use of car catalytic converters, an emerging technology since the 1990s using >50 % of European Pt demand. High and variable historical Pt concentrations (up to 14.6 μg kg−1) in the Seine River sediments may reflect legacy Pt sources due to former anthropogenic activities in this watershed, such as the use of Pt-based catalysts for petroleum refinery since the end of the 1940s, coal handling and precious metals refining, probably concealing the likely presence of an emerging traffic-related Pt signal. This first comparison of historical Pt concentration trends in sediments from contrasting watersheds allows to distinguish signals originating from different natural and anthropogenic sources (background level, historical sources, road traffic).

Constructing surface oxygen defects at CuO–Co3O4 interface to boost toluene oxidation over CuO/Co3O4 catalysts

As a typical heterogeneous catalytic process, the catalytic combustion of toluene over Co3O4-based catalysts is strongly depends on the surface properties of catalysts, especially the concentration of surface oxygen defects. Here, a novel way was proposed to construct chemically bonded CuO–Co3O4 interface by chemical deposition of CuO onto Co3O4 nanoflowers. The interfacial refinement effect between CuO and Co3O4 support disrupted the ordered atomic arrangement and created countless unsaturated coordination sites at CuO–Co3O4 interface, inducing a significant generation of surface oxygen defects. Surface-rich oxygen vacancies enhanced the capacity of 20 %CuO/Co3O4–R to adsorb and activate oxygen species. Benefiting from this, 90 % toluene conversion was reached at 228 °C over 20 %CuO/Co3O4–R, which was much lower than that over 20 %CuO/Co3O4–S prepared by impregnation method and CuO/Co3O4-mix obtained by mechanically mixing way. In-situ DRIFTS analysis revealed that toluene could be directly decomposed into benzaldehyde at the highly defective CuO–Co3O4 interface, leading to toluene oxidation following the path of toluene → benzaldehyde → benzoate → maleic anhydride → water and carbon dioxide over 20 %CuO/Co3O4–R, which was significantly different from decomposition mechanism over 20 %CuO/Co3O4–S. Additionally, 20 %CuO/Co3O4–R displayed terrific recyclability and outstanding stability, showing good application potential.

Boosting Catalytic Combustion of Diesel Soot Particles over Potassium-Promoted CoMn-Co3O4 Dual Spinel Structure Catalyst

Catalytic oxidation is an effective method to remove soot particles from diesel exhaust, and the key aspect of this technology is to develop highly effective catalysts. In this work, a potassium-promoted dual spinel structure was prepared for soot elimination with the self-sacrificing template strategy. The highest activity was presented by the CoMn-0.2H-10%K catalyst under a loose contact mode, with the temperature of soot conversion reaching 90% and turnover frequency value of 365 °C and 3.76×10-3s-1, respectively. The catalyst was found to have a high content of oxygen vacancy and a superior ability for lattice oxygen migration, which led to elevated performance for soot combustion. The formation of K-OMS-2 at the interface between the CoMn spinel and the Co3O4 spinel was one of the reasons for the elevated lattice oxygen migration at low temperatures. This work provides an effective way to prepare transition metal catalysts for soot combustion.

Silica-assisted Pt1/CeO2 single-atom catalyst for enhancing the catalytic combustion performance of VOCs by inducing H2O activation

Silica-assisted Pt1/CeO2 single-atom catalyst for enhancing the catalytic combustion performance of VOCs by inducing H2O activation

Electrochemical and Catalytic Conversion of CO2 into Formic Acid on Cu-InO2 Nano alloy Decorated on Reduced Graphene Oxide (Cu-InO2@rGO)

Electrochemical and Catalytic Conversion of CO2 into Formic Acid on Cu-InO2 Nano alloy Decorated on Reduced Graphene Oxide (Cu-InO2@rGO)

Effects of various pyrolysis temperatures on the physicochemical characteristics of crop straw-derived biochars and their application in tar reforming

As a by-product of the rapid pyrolysis of biomass, biochar not only plays an important role in the biomass conversion process but also holds significant potential value in the catalytic conversion field. This study aimed to evaluate the physicochemical properties changes of biochars at different pyrolysis temperatures and their potential application in tar reforming. Biochars derived from three feedstocks of maize straw (MS), rice husk (RH), and cotton straw (CS) were achieved by fast pyrolysis within a broad temperature range of 300~900 °C, respectively. The results showed that the pyrolysis temperature exerted a pronounced influence on the structural characteristics of biochar. With increasing temperature, the H/C and O/C ratios progressively decreased, accompanied by a significant reduction in oxygen-containing structures. In addition, elevated pyrolysis temperatures contributed favorably to the formation of the crystalline structure of biochar. Raman analysis unveiled a correlation between the fused aromatic ring system and H/C ratios, validating the aromatization progress of biochar. In the tar catalytic reforming process, the three representative biochars, under the effect of MS-600 (standing for MS biochar derived at 600 °C), RH-600, and CS-600 catalysts, exhibited outstanding catalytic performance with tar conversion efficiencies of 73.26%, 68.51%, and 71.43%, respectively. This study provided systematic support for the high-value use of biochar from crop straw.

Efficiency Enhancement in Automotive Catalytic Converters: Recent Developments and Future Directions

Efficiency Enhancement in Automotive Catalytic Converters: Recent Developments and Future Directions

Design and synthesis of SO3H-based ionic liquids for direct catalytic conversion of straw to levulinic acid

The utilization of ionic liquids (ILs) in the conversion of lignocellulose to levulinic acid (LA) is a significant pathway in the field of bio-refinery. In this study, a series of sulfonic-based ILs with elongated alkyl chains were synthesized using density functional theory. These ILs were then utilized for the conversion of straw into LA in a single reaction vessel. The yield of LA was compared between a single solvent (water) and a biphasic system comprising water and methyl isobutyl ketone (MIBK). Among the investigated ILs, [C3SO3HEim]Cl exhibited a higher yield of LA, reaching up to 11.3 wt% in the aqueous phase and 17.8 wt% in the MIBK-water biphasic system. Furthermore, [C3SO3HEim]Cl displayed a high catalytic efficiency (90.4%) and a yield of LA (16.3 wt%) after 5 cycles. These findings suggest that the elongation of alkyl side chains in ILs enhances the solubility of cellulose and increases the yield of LA. The MIBK-water biphasic system promotes the rehydration of hydroxymethylfurfural (HMF) and reduces the residence time of LA in the aqueous phase, thereby optimizing its yield. This innovative approach involving ILs and the MIBK-water biphasic system presents a novel perspective for the production of LA from biomass.

A REVIEW ON THE EFFECTS OF DIETHYL ETHER ON THE CYCLIC VARIATIONS IN DIESEL ENGINES

This review study was compiled from the results of various researches regarding the use of diethyl ether as a fuel or fuel additive in diesel engines. Three techniques are employed for decreasing the hazardous exhaust emissions of diesel engines. The first technique for reducing harmful emissions involves improving combustion by modifying the engine design and fuel injection system; however, this process is both costly and time consuming. The second technique entails using various exhaust gas devices, such as a catalytic converter and diesel particulate filter. However, these devices can have a negative impact on the performance of diesel engines. The last way of reducing emissions and improving diesel engine performance is to use different alternative fuels or fuel additives. Diesel engines primarily release two major pollutants into the atmosphere: oxides of nitrogen (NOx) and particulate matter (PM). It is very difficult to reduce both NOx and PM at the same time in practice. The most research indicates that the most effective way to reduce emissions is to use alternative fuels such as natural gas, biogas, biodiesel, or adding additives to either alternative fuels or conventional diesel fuel. On the other hand, the fuel used has a significant influence on the cycle variations, which in turn has a major effect on the engine performance characteristics, fuel consumption, and exhaust emissions. It is thus essential to comprehensively assess the results of various investigations of alternative fuels or fuel additives before implementation. This study particularly focuses on the use of diethyl ether in diesel engines as fuel or fuel additive in different diesel engine fuels. This review study investigates the effects of the addition of diethyl ether on the cyclic variations, according to the literature.

Polyoxomolybdate-Based Metal-Organic Framework-Derived Cu-Embedded Molybdenum Dioxide Hybrid Nanoparticles as Highly Efficient Electrocatalysts for Al-S Batteries.

High-performance rechargeable aluminum-sulfur batteries (RASB) have great potential for various applications owing to their high theoretical capacity, abundant sulfur resources, and good safety. Nevertheless, the practical application of RASB still faces several challenges, including the polysulfide shuttle phenomenon and low sulfur utilization efficiency. Here, we first developed a synergistic copper heterogeneous metal oxide MoO2 derived from polymolybdate-based metal-organic framework as an efficient catalyst for mitigating polysulfide diffusion. This composite enhances sulfur utilization and electrical conductivity of the cathode. DFT calculations and experimental results reveal the catalyst Cu/MoO2@C not only effectively anchors aluminum polysulfides (AlPSs) to mitigate the shuttle effect, but also significantly promotes the catalytic conversion of AlPSs on the sulfur cathode side during charging and discharging. The unique nanostructure contains abundant electrocatalytic active sites of oxide nanoparticles and Cu clusters, resulting in excellent electrochemical performance. Consequently, the established RASB exhibits an initial capacity of 875 mAh g-1 at 500 mA g-1 and maintains a capacity of 967 mAh g-1 even at a high temperature of 50 °C.

A DFT Study of CO Hydrogenation on Graphene Oxide: Effects of Adding Mn on Fischer–Tropsch Synthesis

The hydrogenation of carbon monoxide (CO) offers a promising avenue for reducing air pollution and promoting a cleaner environment. Moreover, by using suitable catalysts, CO can be transformed into valuable hydrocarbons. In this study, we elucidate the mechanistic aspects of the catalytic conversion of CO to hydrocarbons on the surface of manganese-doped graphene oxide (Mn-doped GO), where the GO surface includes one OH group next to one Mn adatom. To gain insight into this process, we have employed calculations based on the density functional theory (DFT) to explore both the thermodynamic properties and reaction energy barriers. The Mn adatoms were found to significantly activate the catalyst surface by providing stronger adsorption geometries. Our study concentrated on two mechanisms for CO hydrogenation, resulting in either CH4 production via the reaction sequence CO → HCO → CH2O → CH2OH → CH2 → CH3 → CH4 or CH3OH formation through the CO → HCO → CH2O → CH2OH → CH3OH pathway. The results reveal that both products are likely to be formed on the Mn-doped GO surface on both thermodynamic grounds and considering the reaction energy barriers. Furthermore, the activation energies associated with each stage of the synthesis show that the conversion reactions of CH2 + OH → CH3 + O and CH2O + OH → CH2OH + O with energy barriers of 0.36 and 3.86 eV are the fastest and slowest reactions, respectively. The results also indicate that the reactions: CH2OH + OH → CH2 + O+H2O and CH2OH + OH → CH3OH + O are the most exothermic and endothermic reactions with reaction energies of −0.18 and 1.21 eV, respectively, in the catalytic pathways.

Promoting effect and kinetic analysis of Fe-Co bimetallic doping on the LaMnO3 catalytic activity for methane combustion

To enhance the catalyst’s properties, a modified sol–gel method is developed in this study, and a unique perovskite catalyst, LaMnxFeyCo1-x-yO3, is successfully synthesized by doping Fe-Co into the lattice of LaMnO3. The catalytic activity of the synthesized catalysts is initially determined by applying them to methane oxidation. Then, the structural, chemical, and surface properties of these catalysts are systematically evaluated utilizing XRD, BET, O2-TPD, H2-TPR, SEM, and XPS analyses. The modified LaMn0.8Fe0.15Co0.05O3 is shown to exhibit excellent activity (T90 at 486.5 ℃) in methane catalytic combustion, comparable to several standard noble metal materials. Experimental findings indicate that such perovskite structures have a larger specific surface area, an elevated molar ratio of Mn4+, desirable low-temperature reducibility, and excellent oxygen mobility relative to the original LaMnO3. Meanwhile, more efficient electron transfer from Mn4+/Mn3+ redox cycles, as well as the emergence of oxygen defects, significantly contribute to the robust interaction between Fe-Co and LaMnO3. Further reaction kinetic analysis is conducted to determine changes in species components and identify possible catalytic pathways. Notably, Fe-Co co-doping leads to an improvement in the increase of lattice oxygen and CH4 adsorption. In addition, the MVK kinetic mechanism governs methane combustion over LaMn0.8Fe0.15Co0.05O3. This study provides new insights into enhancing energy conversion performance and efficient utilization of ventilation air methane (VAM) through the implementation of highly efficient perovskites.

Assessment of CH4 Emissions in a Compressed Natural Gas-Adapted Engine in the Context of Changes in the Equivalence Ratio

The results of diagnostic tests under steady-state speed conditions of an unloaded engine do not fully reflect the emissivity of vehicles adapted to run on natural gas. Therefore, it is reasonable to pay attention to the emissions performance of these vehicles under dynamic conditions. In this regard, the tests were carried out on a chassis dynamometer with the engine fueled by gasoline and natural gas. Due to the area of operation of natural gas vehicles being usually limited to urban areas, the urban phases of the NEDC (New European Driving Cycle) and WLTC (Worldwide harmonized Light-duty vehicles Test Cycle) were adapted. While CO2 emissions are lower when fueled by natural gas, CH4 emissions can be high, which is related to momentary changes in the composition of the combustible mixture. Although CH4 emissions are higher when the engine runs on natural gas, the CO2eq value is, depending on the driving cycle, about 15–25% lower than when running on petrol. Additionally, studies have shown that in engines adapted to run on CNG (compressed natural gas), it is advisable to consider the use of catalytic converters optimized to run on natural gas, as is the case with vehicles which are factory–adapted to run on CNG.

ПРОГНОЗИРОВАНИЕ ТЕХНОГЕННЫХ ОПАСНОСТЕЙ, ОБУСЛОВЛЕННЫХ ВЫБРОСАМИ ДВУХКОЛЕСНЫХ МОТОТРАНСПОРТНЫХ СРЕДСТВ

The paper analyzes and summarizes data on the emission rates of pollutants by motorcycles and mopeds equipped with internal combustion engines. As a result, it was found that 2-stroke and 4-stroke engines not equipped with an exhaust gas neutralizer demonstrate emissions rates of CO varying in the range of 6,6–32,8 g/km, CH – 0,62–19,26 g/km, NOX – 0,010–0,38 g/km; 2-stroke and 4-strokestroke engines equipped with a catalytic converter, demonstrate emission rates of CO ranging from 0,68 to 12,21 g/km; CH – from 0,10 to 4,06 g/km; NOX – from 0,10 to 0,28 g/km. The results obtained will be used to improve the method for forecasting hazards caused by vehicle emissions.