Records with Keyword: Catalysis
Showing records 1 to 25 of 32. [First] Page: 1 2 Last
Transition Metal Complexes with Amino Acids, Peptides and Carbohydrates in Catalytic Asymmetric Synthesis: A Short Review
Yuliya Titova
June 21, 2024 (v1)
Subject: Biosystems
Keywords: amino acid, asymmetric synthesis, carbohydrate, Catalysis, ligand, modified, organic catalytic synthesis, transition metal complex
The present review is devoted to the application of transition metal complexes with such ligands as amino acids, peptides and carbohydrates in catalysis. The literature published over the past 20 years is surveyed. Among the distinctive features of these ligands are their versatility, optical activity, stability and availability. Furthermore, depending on the specific synthetic task to be solved, these ligands open up almost infinite opportunity for modification. Largely thanks to their multifaceted reactivity, transition metal complexes with amino acids, peptides and carbohydrates can catalyze most of the known chemical reactions affording optically pure compounds. In this review, the emphasis is placed upon C(sp3)−H activation, cross-coupling and hydrogenation (including traditional hydrogenation in the presence of hydrogen gas and hydrogenation with hydrogen transfer) reactions. The choice is not accidental, since these reactions on the one hand display the catalytic versatility of... [more]
Xylose Hydrogenation Promoted by Ru/SiO2 Sol−Gel Catalyst: From Batch to Continuous Operation
Anna Barone, Benedetta Anna De Liso, Henrik Grénman, Kari Eränen, Francesco Taddeo, Claudio Imparato, Antonio Aronne, Vincenzo Russo, Martino Di Serio, Tapio Salmi
June 21, 2024 (v1)
Subject: Materials
Keywords: Catalysis, kinetics, scale-up, xylitol, xylose hydrogenation
Xylose is nowadays converted into xylitol, a popular special chemical sweetener. Xylitol can be used not only in the pharmaceutical and food industries, but also in cosmetics and synthetic resins because of its countless properties. Conventionally, xylitol is produced by slurry reactors operating in batch with dispersed or supported catalysts. Hydrogen is continuously fed to maintain a constant pressure. In this work, the kinetics of the reaction were investigated to find the optimal operating conditions to minimize the by-products obtained. Given the great performances shown by the new Ru/SiO2 sol−gel derived catalyst in glucose hydrogenation, in this work the mentioned catalyst was tested in the hydrogenation of xylose to xylitol both in batch and in continuous production to prove its stability and activity.
Experimental Study about Shale Acceleration on Methane Cracking
Jingkui Mi, Xianming Xiao, Jinhao Guo, Kun He, Xingzhi Ma
August 2, 2023 (v1)
Subject: Materials
Keywords: Catalysis, CH4 cracking experiment, maturity threshold, metal element, shale
The temperature or maturity limit of methane (CH4) cracking is very useful for the determination of the most depth or the highest maturity in natural gas exploration owing to the composition of over mature gas. In this work, three series of CH4 cracking experiments were conducted under different conditions of N2 + CH4, N2 + CH4 + montmorillonite and N2 + CH4 + shale, respectively, in a gold tube system. The experimental results show that some heavy gas with negative carbon isotope composition could be generated in the three series experiments and that shale has more intense catalysis for CH4 cracking than montmorillonite. The catalysis of metal elements distributed in the minerals of shale is attributed to CH4 cracking acceleration. The shale catalysis makes the maturity threshold of CH4 substantial cracking decrease from 6.0%Ro under no catalysis, to 4.5%Ro under a shale system in a geological setting. Nevertheless, we suggest not to lightly practice natural gas exploration in shale w... [more]
Parametric Study of Pt/C-Catalysed Hydrothermal Decarboxylation of Butyric Acid as a Potential Route for Biopropane Production
Iram Razaq, Keith E. Simons, Jude A. Onwudili
April 20, 2023 (v1)
Subject: Materials
Keywords: bioLPG, biopropane, butyric acid, Catalysis, hydrothermal decarboxylation, Pt/C
Sustainable fuel-range hydrocarbons can be produced via the catalytic decarboxylation of biomass-derived carboxylic acids without the need for hydrogen addition. In this present study, 5 wt% platinum on carbon (Pt/C) has been found to be an effective catalyst for hydrothermally decarboxylating butyric acid in order to produce mainly propane and carbon dioxide. However, optimisation of the reaction conditions is required to minimise secondary reactions and increase hydrocarbon selectivity towards propane. To do this, reactions using the catalyst with varying parameters such as reaction temperatures, residence times, feedstock loading and bulk catalyst loading were carried out in a batch reactor. The highest yield of propane obtained was 47 wt% (close to the theoretical decarboxylation yield of 50 wt% on butyric acid basis), corresponding to a 96% hydrocarbon selectivity towards propane. The results showed that the optimum parameters to produce the highest yield of propane, from the rang... [more]
Techno-Economic Analysis of ZnO Nanoparticles Pretreatments for Biogas Production from Barley Straw
Mohamed A. Hassaan, Antonio Pantaleo, Francesco Santoro, Marwa R. Elkatory, Giuseppe De Mastro, Amany El Sikaily, Safaa Ragab, Ahmed El Nemr
April 3, 2023 (v1)
Subject: Materials
Keywords: Antithamnion plumula, barley straw, biogas, Catalysis, cost-benefits analysis, green ZnO nanoparticles, kinetic models, levelized cost of energy
The aim of this study was to analyze the effect of ZnO nanoparticles (ZnO NPs) on the biogas production from mechanically treated barley straw and to perform a techno-economic analysis based on the costs assessment and on the results of biogas production. The structural changes of mechanically pretreated barley straw were observed using FTIR, XRD, TGA, and SEM. Additionally, both green ZnO NPs prepared from red alga (Antithamnion plumula) extract and chemically prepared ZnO NPs were characterized by FTIR, XRD, SEM, and TEM, surface area, and EDX. The results revealed that the biogas production was slightly improved by 14.9 and 13.2% when the barley straw of 0.4 mm was mechanically pretreated with 10 mg/L of both green and chemical ZnO NPs and produced 390.5 mL biogas/g VS and 385 mL biogas/g VS, respectively. On the other hand, the higher concentrations of ZnO NPs equal to 20 mg/L had an inhibitory effect on biogas production and decreased the biogas yield to 173 mL biogas/g VS, which... [more]
The Role of Nanodispersed Catalysts in Microwave Application during the Development of Unconventional Hydrocarbon Reserves: A Review of Potential Applications
Alexey V. Vakhin, Mohammed Amine Khelkhal, Arash Tajik, Marat R. Gafurov, Oleg G. Morozov, Aydar R. Nasybullin, Sergey A. Karandashov, Andrey A. Ponomarev, Tatiana O. Krapivnitskaia, Mikhail Yu. Glyavin, Olga V. Slavkina, Konstantin A. Shchekoldin
March 28, 2023 (v1)
Subject: Materials
Keywords: asphaltenes, Catalysis, electromagnetic heating, heavy oil, in-situ upgrading, microwave, nano-metal particles, transitional metals
Electromagnetic impact on oil reservoir manifests itself in various physical and chemical phenomena and attracts a significant scientific and technological interest. Microwave (MW) radiation heating can be more efficient for the oil recovery than heat transfer by convection or by thermal conduction. MW influence can also lead to significant changes in the physicochemical and rheological properties of oil caused by chemical processes of transformation of the oil high-molecular components such as resins and asphaltenes. The efficiency of transition-metal catalysts applied for the in-situ conversion of hydrocarbons directly in the reservoir might be significantly increased by exposing the oil formation to MW radiation. Actually, transition metals nanoparticles and their oxides are considered as active absorbers of MW radiation and; therefore, they can be used to intensify MW impact on the reservoir. Catalyst particles dispersed in the formation provide enhanced MW sweep. Taken together, t... [more]
Atomic {Pdn+-X} States at Nanointerfaces: Implications in Energy-Related Catalysis
Panagiota Stathi, Maria Solakidou, Areti Zindrou, Loukas Belles, Yiannis Deligiannakis
March 20, 2023 (v1)
Subject: Materials
Keywords: Catalysis, HER, nanoclusters, ORR, palladium, photocatalysis, single-atom, subnanoclusters
Palladium is among the most versatile noble-metal atoms that, when dispersed on solid supports, can be stabilized in 0, +1, +2, +3 redox states. Moreover, despite its noble-metal character, Pd shows a considerable degree of chemical reactivity. In Pd Nanoparticles (NPs), atomic {Pdn+-X} states, where n = 0, 1, 2, 3, and X = atom or hydride, can play key roles in catalytic processes. Pd-oxygen moieties can be stabilized at nanointerfaces of Pd in contact with metal-oxides. These {Pdn+-X}s can be either isolated Pd atoms dispersed on the support, or, more interestingly, atomic states of Pd occurring on the Pd NPs. The present review focuses on the role of such {Pdn+-X} states in catalytic processes related to energy storage or energy conversion, with specific focus on photocatalysis, H2 production reaction (HRR), oxygen reduction reaction (ORR), and water-splitting. Synthesis of atomic {Pdn+-X} states and their detection methodology is among the current challenges. Herein, the chemistry... [more]
Examining Thermal Management Strategies for a Microcombustion Power Device
Bhanuprakash Reddy Guggilla, Jack Perelman Camins, Benjamin Taylor, Smitesh Bakrania
March 9, 2023 (v1)
Subject: Materials
Keywords: Catalysis, Methanol, microcombustion, nanoparticles, platinum, thermoelectric
Microcombustion attracts interest with its promise of energy dense power generation for electronics. Yet, challenges remain to develop this technology further. Thermal management of heat losses is a known hurdle. Simultaneously, non-uniformities in heat release within the reaction regions also affect the device performance. Therefore a combination of thermal management strategies are necessary for further performance enhancements. Here, a bench top platinum nanoparticle based microcombustion reactor, coupled with thermoelectric generators is used. Methanol-air mixtures achieve room temperature ignition within a catalytic cartridge. In the current study, the reactor design is modified to incorporate two traditional thermal management strategies. By limiting enthalpic losses through the exhaust and reactor sides, using multi-pass preheating channels and heat recirculation, expected improvements are achieved. The combined strategies doubled the power output to 1.01 W when compared to the... [more]
The System of Models and Optimization of Operating Modes of a Catalytic Reforming Unit Using Initial Fuzzy Information
Batyr Orazbayev, Ainur Zhumadillayeva, Kulman Orazbayeva, Sandugash Iskakova, Balbupe Utenova, Farit Gazizov, Svetlana Ilyashenko, Olga Afanaseva
March 2, 2023 (v1)
Subject: Materials
Keywords: Catalysis, decision-makers, fuzzy information, heuristic method, hydrogenated, installation of catalytic reforming, mathematical model, methods of fuzzy set theories, multicriteria optimization in a fuzzy environment
The study aims to develop a system of models and a method for optimizing the operating modes of a catalytic reforming unit using fuzzy information, which makes it possible to effectively control the reforming process of the object under study. The object of study of this work is a catalytic reforming unit that has been operating for more than half a century and is characterized by the lack of clarity of some part of the initial information. The research methods are methods of system analysis, mathematical modeling, multicriteria optimization, and expert assessments, as well as methods of theories of fuzzy set theories, which allows formalizing and using fuzzy information, as well as experimental-statistical methods. As a result of the conducted research, the following main results were obtained. Based on a systematic approach, an effective methodology has been developed for developing a system of models of interconnected plant units using various types of available information, includi... [more]
CO2—A Crisis or Novel Functionalization Opportunity?
Daniel Lach, Jaroslaw Polanski, Maciej Kapkowski
March 2, 2023 (v1)
Subject: Materials
Keywords: carbon dioxide (CO2), carbon monoxide (CO), Catalysis, catalyst, catalyst design, CO2 feedstock, heterogenous catalysts database, methanation, photocatalysis, Power-to-Gas
The growing emission of carbon dioxide (CO2), combined with its ecotoxicity, is the reason for the intensification of research on the new technology of CO2 management. Currently, it is believed that it is not possible to eliminate whole CO2 emissions. However, a sustainable balance sheet is possible. The solution is technologies that use carbon dioxide as a raw material. Many of these methods are based on CO2 methanation, for example, projects such as Power-to-Gas, production of fuels, or polymers. This article presents the concept of using CO2 as a raw material, the catalytic conversion of carbon dioxide to methane, and consideration on CO2 methanation catalysts and their design.
The Route from Green H2 Production through Bioethanol Reforming to CO2 Catalytic Conversion: A Review
Eugenio Meloni, Marco Martino, Giuseppina Iervolino, Concetta Ruocco, Simona Renda, Giovanni Festa, Vincenzo Palma
March 1, 2023 (v1)
Subject: Materials
Keywords: bioethanol, carbon capture and storage, carbon capture and utilization, Catalysis, catalytic conversion of CO2, CO2 methanation, reforming, water–gas shift
Currently, a progressively different approach to the generation of power and the production of fuels for the automotive sector as well as for domestic applications is being taken. As a result, research on the feasibility of applying renewable energy sources to the present energy scenario has been progressively growing, aiming to reduce greenhouse gas emissions. Following more than one approach, the integration of renewables mainly involves the utilization of biomass-derived raw material and the combination of power generated via clean sources with conventional power generation systems. The aim of this review article is to provide a satisfactory overview of the most recent progress in the catalysis of hydrogen production through sustainable reforming and CO2 utilization. In particular, attention is focused on the route that, starting from bioethanol reforming for H2 production, leads to the use of the produced CO2 for different purposes and by means of different catalytic processes, pas... [more]
Recent Advances on the Valorization of Glycerol into Alcohols
Louise R. Smith, Mark Douthwaite, Karl Mugford, Nicholas F. Dummer, David J. Willock, Graham J. Hutchings, Stuart H. Taylor
February 27, 2023 (v1)
Subject: Materials
Keywords: Biomass, Catalysis, glycerol, liquid fuels, Methanol, Renewable and Sustainable Energy
Glycerol, a highly functionalised polyol, can be used as a platform molecule to produce a variety of high-value chemicals. As glycerol production is projected to increase over the coming years, it’s critically important that technology and infrastructure are developed to make use of the inevitable surplus. The catalytic production of ‘green’ mono alcohols from glycerol, in the absence of H2, is an emerging area of research that, in recent years, has generated significant industrial interest. Herein, we provide an update on recent advances in this field and discuss challenges which need to be overcome if this approach is to be considered viable industrially. The economic significance of using crude glycerol as a feedstock for glycerol valorisation strategies is also addressed and suggestions for improving the impact of research conducted in this field are proposed.
Mapping of Alternative Oilseeds from the Brazilian Caatinga and Assessment of Catalytic Pathways toward Biofuels Production
Aline Scaramuzza Aquino, Milena Fernandes da Silva, Thiago Silva de Almeida, Filipe Neimaier Bilheri, Attilio Converti, James Correia de Melo
February 27, 2023 (v1)
Subject: Materials
Keywords: biodiesel, biodiversity, Biofuels, biojet, Brazilian tropical flora, Caatinga biome, Catalysis, feedstock, vegetable oils
Biofuels are increasingly important renewable resources in the world’s energy matrix that have challenged the scientific community as well as small and large farmers to develop alternatives to fossil fuels in order to achieve the aims of energy transition. In particular, Brazil’s proven competitiveness in agribusiness together with its rich biodiversity put the country in a key position in the biofuels market. The semiarid Caatinga of northeastern Brazil, an exclusive biome rich in many oilseed species suitable for potential energy purposes, is of particular interest in this field. Nowadays, soybeans are the main feedstock used for the production of biodiesel, but, due to the increasing demand for biofuels, the search for alternative sources of oil from tropical flora with high productivity is crucial. Under this premise, this systematic review focuses on mapping Caatinga’s vegetable oil crops that could be used as alternative raw materials for biofuels’ production in Brazil, in additi... [more]
Hydrogen Vortex Flow Impact on the Catalytic Wall
Vadim Lemanov, Vladimir Lukashov, Konstantin Sharov
February 23, 2023 (v1)
Subject: Materials
Keywords: Catalysis, Hydrogen, impinging jet, large vortex structure (puff)
An experimental study of a hydrogen-containing jet’s impact on a palladium-based catalyst in an air atmosphere was carried out. High-intensity temperature fluctuations on the catalyst surface are obtained in the case when large-scale vortex structures are contained in the jet. These superstructures have a longitudinal size of 20−30 initial jet diameters and a transverse size of about 3−4 diameters. To form such structures, it is necessary to use long, round tubes in the Reynolds number range of 2000−3000 as a source of the impinging jet when a laminar-turbulent transition occurs in the channel according to the intermittency scenario. This effect was obtained at a low hydrogen content in the mixture (XH2 = 3…15%) and a low initial temperature of the catalyst (180 °C). It is shown that the smallest temperature fluctuations are obtained for the laminar flow in the tube (<1.5%), and they are more significant (<4%) for the turbulent regime at low Reynolds numbers (Re < 6000). The g... [more]
Enhanced Hydrogen Storage Performance of MgH2 by the Catalysis of a Novel Intersected Y2O3/NiO Hybrid
Yushan Liu, Shun Wang, Zhenglong Li, Mingxia Gao, Yongfeng Liu, Wenping Sun, Hongge Pan
February 23, 2023 (v1)
Subject: Materials
Keywords: Catalysis, cyclic stability, hydrogen storage, kinetics, MgH2, Y2O3/NiO hybrid
MgH2 is one of the most promising hydrogen storage materials due to its high hydrogen storage capacity and favorable reversibility, but it suffers from stable thermodynamics and poor dynamics. In the present work, an intersected Y2O3/NiO hybrid with spherical hollow structure is synthesized. When introduced to MgH2 via ball-milling, the Y2O3/NiO hollow spheres are crushed into ultrafine particles, which are homogenously dispersed in MgH2, showing a highly effective catalysis. With an optimized addition of 10 wt% of the hybrid, the initial dehydrogenation peak temperature of MgH2 is reduced to 277 °C, lowered by 109 °C compared with that of the bare MgH2, which is further reduced to 261 °C in the second cycle. There is ca. 6.6 wt% H2 released at 275 °C within 60 min. For the fully dehydrogenation product, hydrogenation initiates at almost room temperature, and a hydrogenation capacity of 5.9 wt% is achieved at 150 °C within 150 min. There is still 5.2 wt% H2 desorbed after 50 cycles at... [more]
A Mini Review on Pyrolysis of Natural Algae for Bio-Fuel and Chemicals
Wei Xu, Keqiang Ding, Lihua Hu
February 23, 2023 (v1)
Subject: Materials
Keywords: bio-based chemicals, bio-fuel, Catalysis, natural algae, pyrolysis
The disposal and use of natural algae have recently been the subject of great interest, due to increasing concern for environmental protection and resource utilization. In this paper, a mini review of recent research on the pyrolysis of natural algae, especially the algae from water blooms, is presented. The chemical compositions of the natural algae are summarized, and the pyrolysis properties of different compositions are reviewed. Non-catalytic, catalytic, and integrated catalytic processes are reviewed. Different ideas and methods for the production of bio-fuel or chemicals are discussed. Apparently, deoxygenation and denitrogenation are highly necessary for algae-based bio-fuel and catalysts play an important role in these processes. In addition, the integrated catalytic process, which involves catalysis and other operation conditions aside from the thermal treatment under inert atmosphere, shows potential for the valorization of algae-based bio-oil. Based on the recent concept an... [more]
Catalytic Decomposition of n-C7 Asphaltenes Using Tungsten Oxides−Functionalized SiO2 Nanoparticles in Steam/Air Atmospheres
Karen M. Cerón, Daniela Arias-Madrid, Jaime Gallego, Oscar E. Medina, Lidia E. Chinchilla, Farid B. Cortés, Camilo A. Franco
February 21, 2023 (v1)
Subject: Materials
Keywords: asphaltenes, Catalysis, nanomaterials, silica, sodium tungstate, tungsten oxide, wet combustion
A wide range of technologies are being developed to increase oil recovery, reserves, and perform in situ upgrading of heavy crude oils. In this study, supported tungsten oxide nanoparticles were synthesized, characterized, and evaluated for adsorption and catalytic performance during wet in situ combustion (6% of steam in the air, in volumetric fraction) of n-C7 asphaltenes. Silica nanoparticles of 30 nm in diameter were synthesized using a sol−gel methodology and functionalized with tungsten oxides, using three different concentrations and calcination temperatures: 1%, 3%, 5% (mass fraction), and 350 °C, 450 °C, and 650 °C, respectively. Equilibrium batch adsorption experiments were carried out at 25 ℃ with model solutions of n-C7 asphaltenes diluted in toluene at concentrations from 100 mg·L−1 to 2000 mg·L−1, and catalytic wet in situ combustion of adsorbed heavy fractions was carried out by thermogravimetric analysis coupled to FT-IR. The results showed improvements of asphaltenes d... [more]
A Comprehensive Review of Layered Double Hydroxide-Based Carbon Composites as an Environmental Multifunctional Material for Wastewater Treatment
Yongxiang Huang, Chongmin Liu, Saeed Rad, Huijun He, Litang Qin
February 21, 2023 (v1)
Subject: Materials
Keywords: Adsorption, Carbon, Catalysis, LDH, LDH–C materials, removal mechanism
As is well known, hydrotalcite-like compounds, such as layered-double-hydroxide (LDH) materials, have shown great potential applications in many fields owing to their unique characteristics, including a higher anion exchange capacity, a structure memory effect, low costs, and remarkable recyclability. While the lower surface area and leaching of metal ions from LDH composites reduce the process efficiency of the catalyst, combining LDH materials with other materials can improve the surface properties of the composites and enhance the catalytic performance. Among organic compounds, carbon materials can be used as synergistic materials to overcome the defects of LDHs and provide better performance for environmental functional materials, including adsorption materials, electrode materials, photocatalytic materials, and separation materials. Therefore, this article comprehensively reviews recent works on the preparation and application of layered double-hydroxide-based carbon (LDH−C) compo... [more]
Thermogravimetric Study on Peat Catalytic Pyrolysis for Potential Hydrocarbon Generation
Mohammed A. Khelkhal, Semen E. Lapuk, Aleksey V. Buzyurov, Tatiana O. Krapivnitskaya, Nikolay Yu. Peskov, Andrey N. Denisenko, Alexey V. Vakhin
February 21, 2023 (v1)
Subject: Materials
Keywords: activation energy, Catalysis, enthalpy, entropy, Friedman, Gibbs free energy, KAS, peat, TG, transition metals
Peat has attracted considerable interest as a potential source of alternative fuel in terms of improving hydrocarbons production and satisfying market demand. The next decade is likely to witness a raise in its exploitation. Nevertheless, the characteristics of peat pyrolysis process, via which many experts expect a considerable generation of hydrocarbons, have not been dealt with in depth. In the present study we have applied thermal analysis combined with isoconversional and model methods for clarifying the kinetic and thermodynamic aspects of the process of generating hydrocarbons from peat via pyrolysis in the absence and presence of iron tallates as a catalytic agent. The obtained results showed a positive effect of the opted catalyst on the process of peat pyrolysis. It has been shown that the catalyst is able to reduce the energy of activation of peat pyrolysis process. Moreover, the Gibbs energy, enthalpy and entropy of complex formation values have been found lower in the pres... [more]
Investigation of Catalytic and Photocatalytic Degradation of Methyl Orange Using Doped LaMnO3 Compounds
Paula Sfirloaga, Madalina-Gabriela Ivanovici, Maria Poienar, Catalin Ianasi, Paulina Vlazan
February 21, 2023 (v1)
Subject: Materials
Keywords: Catalysis, doping, kinetic parameters, MO degradation, perovskite
LaMnO3 and 1% Pd-, Ag-, or Y-doped perovskite type nanomaterials were prepared by the sol-gel method, followed by heat treatment at a low temperature (600 °C for 6 h). The investigation through X-ray diffraction and FT-IR spectroscopy indicated that all samples were well crystallized, without secondary phases, and that the transition metal doping changed the crystal structure from the R-3c space group for the undoped LaMnO3 to the Pm-3m space group for the doped perovskite compounds. In this research paper, the efficiencies of the perovskite LaMnO3 materials for methyl orange removal were analyzed, wherein the effect of the doping ions and of the pH on the catalytic activity were studied together with a kinetic approach for the LaMnO3 materials at different values of the pH. Moreover, in the catalytic activity, it should be noted that a slightly better performance was obtained for the Ag-doped materials compared to the Y- and Pd-doped perovskite samples. The results presented for the p... [more]
Catalytic Pyrolysis of Waste Plastics over Industrial Organic Solid-Waste-Derived Activated Carbon: Impacts of Activation Agents
Kezhen Qian, Wenmin Tian, Wentao Li, Shutong Wu, Dezhen Chen, Yuheng Feng
February 21, 2023 (v1)
Subject: Materials
Keywords: Carbon, Catalysis, industrial organic solid waste, pyrolysis of plastics
Renewable source-derived carbon is found to be a green alternative catalyst to zeolite for the pyrolysis of plastics. However, only polyethylene (PE) catalytic pyrolysis over biomass-derived carbon has been extensively studied. In this work, carbon was produced from industrial organic solid waste using different activation agents, and their catalytic performance on the thermal degradation of typical polymers, namely PE, polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) were investigated. The degradation mechanisms and the roles of different active sites of the carbons are discussed. Steam failed to activate the carbon, which has a low specific surface area (6.7 m2/g). Chemical activation using H3PO4 and ZnCl2 produces carbons with higher specific surface area and more porosity. The pyrolysis characteristics of LDPE, PP, PS, and PET catalyzed by the carbons were studied using TGA and a fixed-bed reactor. The thermogravimetric results indicate that all three carb... [more]
Incorporated Metal−Organic Framework Hybrid Materials for Gas Separation, Catalysis and Wastewater Treatment
Zahirah Jaffar, Normawati M. Yunus, Maizatul Shima Shaharun, Muhammad Faizadmesa Allim, Asyraf Hanim Ab Rahim
February 21, 2023 (v1)
Subject: Materials
Keywords: Catalysis, gas separation, hybrid, incorporated, MOF, Wastewater
The special features of metal−organic frameworks (MOFs), namely, tunable porosity, exceptional structure, high surface area and high adsorption capability enable them to be widely studied in many applications including carbon capture and storage (CCS), biomedical engineering, catalysis and pollutant treatment. Despite these remarkable properties, MOFs are known to be moisture-sensitive, hardly recyclable and expensive in fabrication cost which limits their breakthrough performance in more efficient uses. Recently, extensive studies have been devoted to counter those shortcomings by embedding MOFs with support materials using various series of synthetic designs to yield incorporated MOF hybrid materials to counter their limitations. In view of this interest, this review summarizes the latest developments of incorporated MOFs with various materials, namely, ionic liquids (ILs), membranes and metal species. Pre-synthetic and post-synthetic synthesis methods are also discussed. This review... [more]
On Catalytic Kinetics of Enzymes
Jianshu Dong
October 31, 2022 (v1)
Subject: Other
Keywords: biological macro-substrate, Catalysis, catalytic coefficient, catalytic efficiency, catalytic step, enzyme, kinetics, macromolecule, time
Classical enzyme kinetic theories are summarized and linked with modern discoveries here. The sequential catalytic events along time axis by enzyme are analyzed at the molecular level, and by using master equations, this writing tries to connect the microscopic molecular behavior of enzyme to kinetic data (like velocity and catalytic coefficient k) obtained in experiment: 1/k = t equals to the sum of the times taken by the constituent individual steps. The relationships between catalytic coefficient k, catalytic rate or velocity, the amount of time taken by each step and physical or biochemical conditions of the system are discussed, and the perspective and hypothetic equations proposed here regarding diffusion, conformational change, chemical conversion, product release steps and the whole catalytic cycle provide an interpretation of previous experimental observations and can be testified by future experiments.
Nano-Intermediate of Magnetite Nanoparticles Supported on Activated Carbon from Spent Coffee Grounds for Treatment of Wastewater from Oil Industry and Energy Production
Laura Acosta, Dahiana Galeano-Caro, Oscar E. Medina, Farid B. Cortés, Camilo A. Franco
October 14, 2021 (v1)
Keywords: activated carbon, Adsorption, Catalysis, coffee residue, crude oil, magnetite nanoparticles
This work focused on evaluating the adsorptive removal of crude oil using a nano-intermediate based on magnetite nanoparticles supported on activated carbon synthesized from spent coffee grounds and the subsequent catalytic oil decomposition to recover by-products and regenerate the support material. The magnetite nanoparticles were synthesized by the co-precipitation method and were used as active phases on prepared activated carbon. The amount of crude oil adsorbed was determined by adsorption isotherms. In addition, dynamic tests were performed on a packed bed to evaluate the efficiency of the removal process. Thermogravimetric analysis and mass spectrometry were used to evaluate the catalytic powder and the quantification of by-products. Contrasting the results with commercial carbon, the one synthesized from the coffee residue showed a greater affinity for the oil. Likewise, the adsorption capacity increased by doping activated carbon with magnetite nanoparticles, obtaining an eff... [more]
Economic and Environmental Assessment of Catalytic and Thermal Pyrolysis Routes for Fuel Production from Lignocellulosic Biomass
Akshay D. Patel, Masoud Zabeti, K. Seshan, Martin K. Patel
July 19, 2021 (v1)
Keywords: abatement cost, biofuel, Catalysis, economics, lifecycle environmental impacts, lignocellulosic biomass, pyrolysis, Renewable and Sustainable Energy
Meeting the transport needs of a growing world population makes it imperative to develop renewable and sustainable routes to production of liquid fuels. With a market-driven economic structure and pressing environmental issues, it is essential that these new routes provide environmental benefits while being economically viable. Conversion of second-generation lignocellulosic biomass resources to fuels via pyrolysis represents an important technological route. In this article, we report comparative assessment of the economic and lifecycle environmental aspects for catalytic and thermal pyrolysis. The goal of this assessment is two-fold: one is to understand the potential of this conversion route via the catalytic and thermal processes and second is to provide feedback for further development of catalysts for various stages of this conversion. The complete assessment is interdisciplinary in nature and connects the laboratory experiments with contextual sustainability assessment. Three ca... [more]
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