Records with Subject: Reaction Engineering
Showing records 1 to 25 of 261. [First] Page: 1 2 3 4 5 Last
Microalgal Consortia for Waste Treatment and Valuable Bioproducts
Shousong Zhu, Lauren Higa, Antonia Barela, Caitlyn Lee, Yinhua Chen, Zhi-Yan Du
March 20, 2023 (v1)
Keywords: biofuel, biomass production, microalgal consortia, resource recovery, symbiosis, wastewater treatment
Microalgae have been considered a promising and sustainable candidate for wastewater treatment and valuable bioproducts, such as feedstocks for food, nutrients, and energy. However, many challenging bottlenecks, such as low biomass productivity, expensive biomass harvesting techniques, and inefficient extraction of biofuels restrict its large-scale commercial production. Symbiotic relationships between microalgae and bacteria, also known as microalgal consortia, have proven to be effective solutions for mitigating technical and economic limitations. The natural and artificial symbiotic microalgal consortia combine microorganisms with various metabolic activities, which leads to valuable biomass production and the removal of nutrients, pharmaceuticals, and personal care products (PPCP) from wastewater. Many microalgal consortia have been applied for various wastewater treatments with reduced energy costs and higher efficiency in recovering valuable resources. In this study we review the... [more]
Py-GC-MS Study on Catalytic Pyrolysis of Biocrude Obtained via HTL of Fruit Pomace
Mariusz Wądrzyk, Marek Plata, Kamila Zaborowska, Rafał Janus, Marek Lewandowski
March 7, 2023 (v1)
Keywords: bio-oil, biocrude, Biomass, bioproducts, blackcurrant pomace, fruit pomace, hydrothermal liquefaction, pyrolysis, Renewable and Sustainable Energy, upgrading
Herein, we proposed new two-stage processing of blackcurrant pomace toward a value-added, hydrocarbon-rich biocrude fraction. The approach consisted of thermochemical liquefaction of a wet-type organic matter into liquid biocrude followed by its upgrade by thermal and catalytic pyrolysis. Particularly, we put effort into investigating the effect of selected catalysts (ZSM-5 and HY zeolite) on the composition of the volatiles released during the pyrolysis of the biocrude. The latter was obtained through liquefaction of the raw material in the binary solvent system of water and isopropanol. The biocrude yield accounted for ca. 45 wt.% of the initial dry biomass. It was a complex mixture of various component groups with an abundant share of oxygenates, especially carboxylic acids and esters. Thereafter, the biocrude was subjected to a pyrolysis study performed by means of the microscale coupled pyrolysis-gas chromatography-mass spectrometry technique (Py-GC-MS). The dominant components id... [more]
Recent Achievements in Microalgal Photobiological Hydrogen Production
Eleftherios Touloupakis, Cecilia Faraloni, Ana Margarita Silva Benavides, Giuseppe Torzillo
March 7, 2023 (v1)
Keywords: biohydrogen, Chlamydomonas reinhardtii, Chlorella sp., light conversion efficiency, microalgae, photobioreactors
It is well known that over the last 60 years the trend of long-lived greenhouse gas emissions have shown a strong acceleration. There is an increasing concern and a mounting opposition by public opinion to continue with the use of fossil energy. Western countries are presently involved in a so-called energy transition with the objective of abandoning fossil energy for renewable sources. In this connection, hydrogen can play a central role. One of the sustainable ways to produce hydrogen is the use of microalgae which possess two important natural catalysts: photosystem II and hydrogenase, used to split water and to combine protons and electrons to generate gaseous hydrogen, respectively. For about 20 years of study on photobiological hydrogen production, our scientific hopes were based on the application of the sulfur protocol, which indisputably represented a very important advancement in the field of hydrogen production biotechnology. However, as reported in this review, there is inc... [more]
Microalgal Systems for Wastewater Treatment: Technological Trends and Challenges towards Waste Recovery
Etiele G. Morais, Nathana L. Cristofoli, Inês B. Maia, Tânia Magina, Paulo R. Cerqueira, Margarida Ribau Teixeira, João Varela, Luísa Barreira, Luísa Gouveia
March 6, 2023 (v1)
Keywords: agroindustrial wastewater, industrial wastewater, microalgal bioproducts, strain isolation, urban wastewater
Wastewater (WW) treatment using microalgae has become a growing trend due the economic and environmental benefits of the process. As microalgae need CO2, nitrogen, and phosphorus to grow, they remove these potential pollutants from wastewaters, making them able to replace energetically expensive treatment steps in conventional WW treatment. Unlike traditional sludge, biomass can be used to produce biofuels, biofertilizers, high value chemicals, and even next-generation growth media for “organically” grown microalgal biomass targeting zero-waste policies and contributing to a more sustainable circular bioeconomy. The main challenge in this technology is the techno-economic feasibility of the system. Alternatives such as the isolation of novel strains, the use of native consortia, and the design of new bioreactors have been studied to overcome this and aid the scale-up of microalgal systems. This review focuses on the treatment of urban, industrial, and agricultural wastewaters by microa... [more]
Quantifying Environmental and Economic Impacts of Highly Porous Activated Carbon from Lignocellulosic Biomass for High-Performance Supercapacitors
Yuxi Wang, Jingxin Wang, Xufeng Zhang, Debangsu Bhattacharyya, Edward M. Sabolsky
March 3, 2023 (v1)
Keywords: activated carbon, bioproducts, economic feasibility, environmental impacts, lignocellulosic biomass, supercapacitor electrodes
Activated carbons (AC) from lignocellulosic biomass feedstocks are used in a broad range of applications, especially for electrochemical devices such as supercapacitor electrodes. Limited studies of environmental and economic impacts for AC supercapacitor production have been conducted. Thus, this paper evaluated the environmental and economic impacts of AC produced from lignocellulosic biomass for energy-storage purposes. The life cycle assessment (LCA) was employed to quantify the potential environmental impacts associated with AC production via the proposed processes including feedstock establishment, harvest, transport, storage, and in-plant production. A techno-economic model was constructed to analyze the economic feasibility of AC production, which included the processes in the proposed technology, as well as the required facility installation and management. A base case, together with two alternative scenarios of KOH-reuse and steam processes for carbon activation, were evaluat... [more]
Taxonomic and Biochemical Characterization of Microalga Graesiella emersonii GEGS21 for Its Potential to Become Feedstock for Biofuels and Bioproducts
Nam Seon Kang, Kichul Cho, Sung Min An, Eun Song Kim, Hyunji Ki, Chung Hyeon Lee, Grace Choi, Ji Won Hong
February 24, 2023 (v1)
Keywords: Biofuels, fatty acids, Graesiella emersonii, lutein, microalgae, omega-6, pigments, taxonomy
is a commercially exploitable source of bioactive compounds and biofuels with potential applications in microalgae-based industries. Despite this, little taxonomical information is available. Therefore, proper identification and characterization are needed for the sustainable utilization of isolated microalgae. In this study, an axenically isolated unicellular green alga from the Geumgang Estuary, Korea was investigated for its morphological, molecular, and biochemical characteristics. The morphological characteristics were typical of G. emersonii. Molecular phylogenetic analysis of the 18S rDNA sequence verified that the isolate belonged to G. emersonii and was subsequently named G. emersonii GEGS21. It was isolated from brackish water, and its optimal growth temperature, salinity, and light intensity were at 28−32 °C, 0 M NaCl, and 130−160 µmol m−2 s−1, respectively. The strain thrived over a range of temperatures (5−40 °C) and withstood up to 0.5 M NaCl. The isolate was rich in omeg... [more]
The Role of Heterotrophic Microalgae in Waste Conversion to Biofuels and Bioproducts
Teresa Lopes da Silva, Patrícia Moniz, Carla Silva, Alberto Reis
February 23, 2023 (v1)
Keywords: heterotrophic microalgae, high value-added products, wastes treatment
In the last few decades, microalgae have attracted attention from the scientific community worldwide, being considered a promising feedstock for renewable energy production, as well as for a wide range of high value-added products such as pigments and poly-unsaturated fatty acids for pharmaceutical, nutraceutical, food, and cosmetic markets. Despite the investments in microalgae biotechnology to date, the major obstacle to its wide commercialization is the high cost of microalgal biomass production and expensive product extraction steps. One way to reduce the microalgae production costs is the use of low-cost feedstock for microalgae production. Some wastes contain organic and inorganic components that may serve as nutrients for algal growth, decreasing the culture media cost and, thus, the overall process costs. Most of the research studies on microalgae waste treatment use autotrophic and mixotrophic microalgae growth. Research on heterotrophic microalgae to treat wastes is still sca... [more]
Solvothermal Liquefaction of Blackcurrant Pomace in the Water-Monohydroxy Alcohol Solvent System
Mariusz Wądrzyk, Łukasz Korzeniowski, Marek Plata, Rafał Janus, Marek Lewandowski, Grzegorz Borówka, Przemysław Maziarka
February 22, 2023 (v1)
Keywords: binary solvent system, biochar, biocrude, bioproducts, blackcurrant pomace, liquefaction, thermochemical conversion, waste valorization
Wet organic wastes are especially troublesome in valorization. Therefore, innovative solutions are still in demand to make valorization feasible. In this study, we tested a new transformation route of a blackcurrant pomace as a high-moisture industrial waste through a series of high-temperature and pressure solvothermal liquefaction experiments. The feedstock was directly converted under near-critical conditions of the binary solvent system (water/2-propanol). The goal was to examine the effect of conversion parameters (temperature, biomass-to-solvent ratio) on the change in the yield of resultant bioproducts, as well as the quality thereof. The experiments were conducted in a batch autoclave at a temperature between 250 and 300 °C. The main product of the transformation was liquid biocrude, which was obtained with the highest yield (ca. 52 wt.%) at 275 °C. The quality of biocrude was examined by ATR-FTIR, GC-MS, and elemental analysis. The ultimate biocrude was a viscous heterogeneous... [more]
A Temporal Evolution Perspective of Lipase Production by Yarrowia lipolytica in Solid-State Fermentation
Felipe Valle do Nascimento, Ailton Cesar Lemes, Aline Machado de Castro, Argimiro Resende Secchi, Maria Alice Zarur Coelho
February 21, 2023 (v1)
Keywords: agro-industrial residues, bioreactors, enzyme production, solid-state fermentation, Yarrowia lipolytica
Lipases are enzymes that, in aqueous or non-aqueous media, act on water-insoluble substrates, mainly catalyzing reactions on carboxyl ester bonds, such as hydrolysis, aminolysis, and (trans)esterification. Yarrowia lipolytica is a non-conventional yeast known for secreting lipases and other bioproducts; therefore, it is of great interest in various industrial fields. The production of lipases can be carried on solid-state fermentation (SSF) that utilizes solid substrates in the absence, or near absence, of free water and presents minimal problems with microbial contamination due to the low water contents in the medium. Moreover, SSF offers high volumetric productivity, targets concentrated compounds, high substrate concentration tolerance, and has less wastewater generation. In this sense, the present work provides a temporal evolution perspective regarding the main aspects of lipase production in SSF by Y. lipolytica, focusing on the most relevant aspects and presenting the potential... [more]
Transcriptome Analysis Reveals the Involvement of Alternative Splicing in the Nitrogen Starvation Response of Chlamydomonas reinhardtii
Xingcai Yang, Xiangyu Li, Jialin Zhao, Mingshi Xie, Xinyi Li, Bin Jia, Ying Huang
February 21, 2023 (v1)
Keywords: abiotic stress, alternative splice, C. reinhardtii, post-transcriptional regulation, spliceosome
Alternative splicing (AS) is a regulatory mechanism of post-transcriptional regulation that plays an important role in plant response to abiotic stresses. However, corresponding research involving the mechanism of AS in the nitrogen starvation response of C. reinhardtii is rare. This study performed a comprehensive and systematic analysis of AS events in C. reinhardtii at nine time points (0 h, 10 m, 30 m, 1 h, 6 h, 8 h, 24 h, and 48 h) under nitrogen starvation. It used STAR and rMATS tools to identify and quantify the probability of the AS event happening through the transcriptome high-throughput sequencing data. A total of 5806 AS events in 3500 genes were identified, and the retained intron and skipped exon were considered the main AS types. The genes related to the AS event in nitrogen starvation were mainly involved in spliceosome and transporter and enriched in the citrate cycle and fatty acid degradation pathways. These results suggested that AS may play an important role in th... [more]
Solid-State Fermentation from Organic Wastes: A New Generation of Bioproducts
Nicolás Oiza, Javier Moral-Vico, Antoni Sánchez, Edgar Ricardo Oviedo, Teresa Gea
February 21, 2023 (v1)
Keywords: biopesticide, bioproducts, biosurfactant, circular bioeconomy, organic waste, solid-state fermentation
Solid-state fermentation (SSF) is part of the pathway to consolidate waste as a relevant alternative for the valorization of organic waste. The objective of SSF is to produce one or several bioproducts of added value from solid substrates. Solid-state fermentation can use a wide variety of organic waste as substrates thus, it is an excellent candidate in the framework of the circular bioeconomy to change the status of waste from feedstock. The development of SSF was boosted in the previous decade by scientific efforts devoted to the production of hydrolytic enzymes. Nowadays, SSF has expanded to other valuable products: biosurfactants, biopesticides, aromas, pigments, and bio-flocculants, among others. This review explores the conditions to obtain the main emerging SSF products and highlight and discuss the challenges related to the scale-up of these processes and the bioproducts downstream, which hamper their further commercialization.
Morphology and Structure Controls of Single-Atom Fe−N−C Catalysts Synthesized Using FePc Powders as the Precursor
Ning Yan, Fan Liu, Xu Meng, Meng Qin, Guangqi Zhu, Luxia Bu, Zigeng Liu, Wei Wang
January 24, 2022 (v1)
Keywords: Fe–N–C, morphology, ORR
Understanding the origin of the high electrocatalytic activity of Fe−N−C electrocatalysts for oxygen reduction reaction is critical but still challenging for developing efficient sustainable nonprecious metal catalysts used in fuel cells. Although there are plenty of papers concerning the morphology on the surface Fe−N−C catalysts, there is very little work discussing how temperature and pressure control the growth of nanoparticles. In our lab, a unique organic vapor deposition technology was developed to investigate the effect of the temperature and pressure on catalysts. The results indicated that synthesized catalysts exhibited three kinds of morphology—nanorods, nanofibers, and nanogranules—corresponding to different synthesis processes. The growth of the crystal is the root cause of the difference in the surface morphology of the catalyst, which can reasonably explain the effect of the temperature and pressure. The oxygen reduction reaction current densities of the different catal... [more]
Case Study of Anaerobic Digestion Process Stability Detected by Dissolved Hydrogen Concentration
Daniela Platošová, Jiří Rusín, Jan Platoš, Kateřina Smutná, Roman Buryjan
January 24, 2022 (v1)
Keywords: amperometric sensor, anaerobic digestion, dissolved hydrogen, Fermentation, rotary bioreactor
The paper presents the results of a laboratory experiment of mesophilic single-stage anaerobic digestion performed to verify the possibility of early detection of process instability and reactor overload by evaluating the course of dissolved hydrogen concentration of the main intermediate. The digestion process was run in a Terrafors IS rotary drum bioreactor for 230 days. The substrate dosed on weekdays was food leftovers from the university canteen. At an average temperature of 37 °C, an organic loading of volatiles of 0.858 kg m−3 day−1 and a theoretical retention time of 259 days, biogas production of 0.617 Nm3 kg VS−1 was achieved with a CH4 content of 51.7 vol. %. The values of the established FOS/TAC stability indicator ranged from 0.26 to 11.4. The highest value was reached when the reactor was overloaded. The dissolved hydrogen concentration measured by the amperometric microsensor ranged from 0.039−0.425 mg dm−3. Data were statistically processed using Pearson’s correlation c... [more]
Batch Mode Reactor for 3,5-Dinitrosalicylic Acid Degradation by Phanerochaete chrysosporium
Rafał Madaj, Witold Sroczyński, Michał Sójka, Tomasz P. Olejnik, Elżbieta Sobiecka
January 24, 2022 (v1)
Keywords: batch reactor, biodegradation, Phanerochaete chrysosporium, the 3,5-dinitrosalicylic acid
A new batch mode reactor was constructed to conduct continuous biodegradation of 3,5-dinitrosalicylic acid. Various types of matrices with immobilized Phanerochaete chrysosporium were immersed in a solution containing pollutant and mineral nutrients. Three parameters were chosen to optimize the process. The nitrate and nitrite ions concentrations and HPLC analysis were used to prove the biodegradation of 3,5-dinitrosalicylic acid, and the mixed effects model using one-factor ANOVA was used for statistical calculations. The results showed the correlation between the initial pH, a medium composition, and the process time. In pH = 6.5, the degradation effectiveness was estimated at 99% decrease in the substrate within 14 days, while an 80% decrease of acid concentration was indicated in pH = 3.5 after 28 days of the process duration.
Development of Carbonization and a Relatively High-Temperature Halogenation Process for the Removal of Radionuclides from Spent Ion Exchange Resins
Hee-Chul Yang, Hyeon-Oh Park, Kyu-Tae Park, Sung-Jun Kim, Hyung-Ju Kim, Hee-Chul Eun, Keunyoung Lee
January 24, 2022 (v1)
Keywords: carbonization, halogenation, kinetic analysis, numerical optimization, spent resin, thermodynamic analysis
This study investigated a two-step thermochemical treatment process consisting of carbonization and halogenation for the removal of radionuclides from spent cation-exchange resin (CER). Based on a thermal analysis of cation-exchange resins, we propose a two-step thermochemical treatment process involving the conversion of spent CER into pyrocarbon and then the removal of radioactive elements from the carbonized CER by converting them volatile halides at very high temperatures. The proposed process mainly consists of a carbonization and halogenation reactor, a UHC (unburned hydrocarbon) combustor, and wet scrubber. A step-by-step experimental and numerical optimization study was conducted with the carbonization and halogenation reactor and the UHC combustor. The optimum operating conditions could be established based on the results of a thermal analysis of the CER, a nonisothermal kinetic analysis, a numerical modeling study of a plug flow reactor (PFR)-type combustor, and a thermodynam... [more]
A Process for the Synthesis and Use of Highly Aromatic Organosilanes as Additives for Poly(Vinyl Chloride) Films
Safaa H. Mohamed, Ayad S. Hameed, Gamal A. El-Hiti, Dina S. Ahmed, Mohammed Kadhom, Mohammed A. Baashen, Muna Bufaroosha, Ahmed A. Ahmed, Emad Yousif
December 6, 2021 (v1)
Keywords: dehydrochlorination, organosilanes, photostability, Schiff’s bases, ultraviolet irradiation absorbers, weight and molecular weight loss
Three organosilanes were synthesized in good yields from the condensation of 4,4′,4″-((phenylsilanetriyl)tris(oxy))tribenzaldehyde and 4-substituted anilines under acidic conditions. The structure of the organosilanes was confirmed using a variety of techniques. Organosilanes were mixed with poly(vinyl chloride) (PVC) and homogenous films were produced. The effect of long-term irradiation on the films containing organosilanes was tested using various methods. Monitoring the infrared spectra of PVC films before, during and after irradiation processes showed the formation of side products comprising polyene, carbonyl and hydroxyl groups. The intensities of absorption bands due to these functional groups were much lower in the presence of organosilanes as compared to the blank film. Also, the decrease in the weight and molecular weight of PVC films after irradiation was lower in the presence of organosilanes. Additionally, there was a minimal surface change of irradiated PVC in the presen... [more]
Influence of the Ni-Co/Al-Mg Catalyst Loading in the Continuous Aqueous Phase Reforming of the Bio-Oil Aqueous Fraction
Pablo Lozano, Ana I. Simón, Lucía García, Joaquín Ruiz, Miriam Oliva, Jesús Arauzo
October 14, 2021 (v1)
Keywords: acetic acid, acetol, aqueous fraction, aqueous phase reforming, bio-oil, Butanol, Ni catalyst
The effect of catalyst loading in the Aqueous Phase Reforming (APR) of bio-oil aqueous fraction has been studied with a Ni-Co/Al-Mg coprecipitated catalyst. Because of the high content of water in the bio-oil aqueous fraction, APR could be a useful process to convert this fraction into valuable products. Experiments of APR with continuous feeding of aqueous solution of acetol, butanol and acetic acid as the only compound, together with a simulated and a real aqueous fraction of bio-oil, were carried out. Liquid products in the liquid effluent of the APR model compounds were quantified and the reaction pathways were revised. The increase of catalyst loading produced an increase of gas production and a gas with higher alkanes content. Acetol was the compound with the highest reactivity while the conversion of acetic acid was very low. The presence of acetic acid in the feed caused catalyst deactivation.
Microemulsion vs. Precipitation: Which Is the Best Synthesis of Nickel−Ceria Catalysts for Ethanol Steam Reforming?
Cristina Pizzolitto, Federica Menegazzo, Elena Ghedini, Arturo Martínez Arias, Vicente Cortés Corberán, Michela Signoretto
October 14, 2021 (v1)
Keywords: coke resistance, ethanol steam reforming, lanthanum doping, microemulsion, Ni/CeO2
Ethanol steam reforming is one of the most promising ways to produce hydrogen from biomass, and the goal of this research is to investigate robust, selective and active catalysts for this reaction. In particular, this work is focused on the effect of the different ceria support preparation methods on the Ni active phase stabilization. Two synthetic approaches were evaluated: precipitation (with urea) and microemulsion. The effects of lanthanum doping were investigated too. All catalysts were characterized using N2-physisorption, temperature programmed reduction (TPR), XRD and SEM, to understand the influence of the synthetic approach on the morphological and structural features and their relationship with catalytic properties. Two synthesis methods gave strongly different features. Catalysts prepared by precipitation showed higher reducibility (which involves higher oxygen mobility) and a more homogeneous Ni particle size distribution. Catalytic tests (at 500 °C for 5 h using severe Ga... [more]
Investigation of Ni−Fe−Cu-Layered Double Hydroxide Catalysts in Steam Reforming of Toluene as a Model Compound of Biomass Tar
David Díez, Ana Urueña, Gregorio Antolín
October 14, 2021 (v1)
Keywords: gasification, hydrogen production, hydrotalcite, layered double hydroxide, Ni-based catalyst, tar, toluene steam reforming
This work focused on the synthesis of a catalyst based on layered double hydroxides with a molar cation concentration Ni/Cu/Fe/Mg/Al of 30/5/5/40/20 and its performance in the steam reforming of toluene as a model compound of biomass tar. Its performance at different temperatures (500, 600, 700, 800, and 900 °C) and steam/carbon molar ratios (S/C ratios) (1, 2, 4, 6, 8) was studied. The contact time used was 0.32 g h mol−1. The catalyst obtained allowed us to reach 98−99.87% gas conversion of toluene with a low carbon deposition on catalyst surface (1.4 wt %) at 800 °C and S/C = 4. In addition, conversions in the range of 600−700 °C were higher than 80% and 90%, respectively, and the type of carbon deposited on the catalyst was found to be filamentous, which did not significantly reduce the performance of the catalyst.
Evaluation of Novel Bio-Based Amino Curing Agent Systems for Epoxy Resins: Effect of Tryptophan and Guanine
Stefano Merighi, Laura Mazzocchetti, Tiziana Benelli, Loris Giorgini
September 22, 2021 (v1)
Keywords: DSC, epoxy resin, guanine, hardener system, renewable material, tryptophan
In order to obtain an environmentally friendly epoxy system, L-tryptophan and guanine were investigated as novel green curing agents for the cross-link of diglycidyl ether of Bisphenol A (DGEBA) as a generic epoxy resin model of synthetic and analogous bio-based precursors. In particular, L-tryptophan, which displays high reaction temperature with DGEBA, was used in combination with various bio-based molecules such as urea, theobromine, theophylline, and melamine in order to increase the thermal properties of the epoxy resin and to reduce the crosslinking reaction temperature. Later, in order to obtain similar properties using a single product, guanine, a totally heterocyclic molecule displaying amine functional groups, was tested as hardener for DGEBA. The thermal behavior of the precursor mixtures was evaluated by dynamic differential scanning calorimetry (DSC) leading to a preliminary screening of different hardening systems which offered a number of interesting hints in terms of bi... [more]
Lumped Kinetic Modeling of Polypropylene and Polyethylene Co-Pyrolysis in Tubular Reactors
Andreas E. Lechleitner, Teresa Schubert, Wolfgang Hofer, Markus Lehner
September 22, 2021 (v1)
Keywords: feedstock recycling, kinetic modeling, lumped modeling, plastic pyrolysis, ReOil
The recycling rates, especially those from plastic packaging waste, have to be increased according to the European Union directive in the next years. Besides many other technologies, the pyrolysis of plastic wastes seems to be an efficient supplementary opportunity to treat mixed and unpurified plastic streams. For this reason, a pyrolysis process was developed for the chemical recycling of hydrocarbons from waste polyolefins. The obtained products can be further processed and upgraded in crude oil refineries, so that also monomers can be recovered, which are used for the plastic polymerization again. However, to achieve a scale up to a demo plant, a kinetic model for predicting the yields of the plastic pyrolysis in a tubular reactor is needed. For this reason, a pilot plant was built, in which different plastics and carrier fluids can be tested. Based on the data generated at the pilot plant, a very practical and suitable model was found to describe the plastic co-pyrolysis of the ca... [more]
Insights into Thermal Degradation Behaviors and Reaction Kinetics of Medical Waste Infusion Bag and Nasal Oxygen Cannula
Lifan Zhang, Jiajia Jiang, Tengkun Ma, Yong Pan, Yanjun Wang, Juncheng Jiang
September 21, 2021 (v1)
Keywords: activation energy, medical plastic waste, reaction mechanism, thermal degradation, thermogravimetric
The thermal degradation behaviors and reaction kinetics of medical waste infusion bag (IB) and nasal oxygen cannula (NOC) were investigated under inert atmosphere with the heating rates of 5, 10, 15, and 25 K·min−1. Ozawa−Flynn−Wall (OFW), Kissinger−Akahira−Sunose (KAS), and Friedman were employed to estimate the activation energy. Coats−Redfern and Kennedy−Clark methods were adopted to predict the possible reaction mechanism. The results suggested that the reaction mechanism of IB pyrolysis was zero-order, and that of NOC pyrolysis was concluded that zero-order for the first stage and three-dimensional diffusion Jander equation for the second stage. Based on the kinetic compensation effect, the reconstructed reaction models for IB and NOC pyrolysis were elaborated by introducing adjustment functions. The results indicated that the reconstructed model fitted well with the experimental data. The results are helpful as a reference and provide guidance for the determination of IB and NOC... [more]
Effect of Ni(NO3)2 Pretreatment on the Pyrolysis of Organsolv Lignin Derived from Corncob Residue
Wenli Wang, Yichen Liu, Yue Wang, Longfei Liu, Changwei Hu
September 21, 2021 (v1)
Keywords: bio-oil, lignin, Ni(NO3)26H2O, pretreatment, pyrolysis
The thermal degradation of lignin for value-added fuels and chemicals is important for environment improvement and sustainable development. The impact of pretreatment and catalysis of Ni(NO3)2 on the pyrolysis behavior of organsolv lignin were studied in the present work. Samples were pyrolyzed at 500 ∘C with an upward fixed bed, and the characteristics of bio-oil were determined. After pretreatment by Ni(NO3)2, the yield of monophenols increased from 23.3 wt.% to 30.2 wt.% in “Ni-washed” and decreased slightly from 23.3 wt.% to 20.3 wt.% in “Ni-unwashed”. Meanwhile, the selective formation of vinyl-monophenols was promoted in “Ni-unwashed”, which indicated that the existence of nickel species promoted the dehydration of C-OH and breakage of C-C in pyrolysis. In comparison with “Water”, HHV of bio-oil derived from “Ni-unwashed” slightly increased from 27.94 mJ/kg to 28.46 mJ/kg, suggesting that the lowering of oxygen content in bio-oil is associated with improved quality. Furthermore,... [more]
Iron-Based Catalytically Active Complexes in Preparation of Functional Materials
Katarzyna Rydel-Ciszek, Tomasz Pacześniak, Izabela Zaborniak, Paweł Błoniarz, Karolina Surmacz, Andrzej Sobkowiak, Paweł Chmielarz
July 29, 2021 (v1)
Keywords: “green” oxidants, controlled radical polymerization, heterogeneous catalysis, homogeneous catalysis, iron-based catalysts, oxidation processes
Iron complexes are particularly interesting as catalyst systems over the other transition metals (including noble metals) due to iron’s high natural abundance and mediation in important biological processes, therefore making them non-toxic, cost-effective, and biocompatible. Both homogeneous and heterogeneous catalysis mediated by iron as a transition metal have found applications in many industries, including oxidation, C-C bond formation, hydrocarboxylation and dehydration, hydrogenation and reduction reactions of low molecular weight molecules. These processes provided substrates for industrial-scale use, e.g., switchable materials, sustainable and scalable energy storage technologies, drugs for the treatment of cancer, and high molecular weight polymer materials with a predetermined structure through controlled radical polymerization techniques. This review provides a detailed statement of the utilization of homogeneous and heterogeneous iron-based catalysts for the synthesis of bo... [more]
Methanol Synthesis with Steel-Mill Gases: Simulation and Practical Testing of Selected Gas Utilization Scenarios
Kai Girod, Heiko Lohmann, Stefan Schlüter, Stefan Kaluza
July 29, 2021 (v1)
Keywords: Carbon2Chem®, gas recirculation, MegaMax®800, methanol synthesis, process simulation, steel-mill gases
The utilization of CO2-containing steel-mill gases for synthesis of methanol was investigated. Four different scenarios with syngas derived from steel-mill gases were considered. A process model for an industrial methanol production including gas recirculation was applied to provide realistic conditions for catalyst performance tests. A long-term test series was performed in a close-to-practice setup to demonstrate the stability of the catalyst. In addition, the experimental results were used to discuss the quality of the simulation results. Kinetic parameters of the reactor model were fitted. A comparison of two different kinetic approaches and the experimental results revealed which approach better fits CO-rich or CO2-rich steel-mill gases.
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