Addition Of Catalyst Research Articles

Studies on the Thermochemical Conversion of Waste Tyre Rubber—A Review

Waste from scrap tyres, due to its high volume (17 million Mg per year) and durability resulting from the physical and chemical properties, requires innovative approaches for efficient and environmentally friendly management. In many countries, the landfilling of waste tyres is banned (e.g., EU, USA, UK); however, waste tyres can be a source of valuable materials such as carbon black, pyrolysis oil, hydrogen-rich syngas, tyre char, as well as energy. The purpose of this article is to provide a synthesis of the state of knowledge regarding the thermal conversion of waste tyres by pyrolysis and gasification, taking into account the use of different measurement techniques and reactor types. These technologies are forward-looking and have a high degree of flexibility in terms of product sourcing, depending on the process conditions. The properties of waste from used tyres were analysed, i.e., the composition of the content of individual components and the main chemical substances. The results encompassed ultimate and proximate analyses of rubber from tyres, as well as the physical and chemical parameters of the tyre char obtained through pyrolysis. This article compiles available literature data regarding the impact of process and raw material parameters, such as temperature and time conditions, pressure, particle size, and catalyst addition on the pyrolysis and gasification processes. It also explores the influence of these factors on the yield and properties of the products, including pyrolysis oil, gas, synthesis gas, and tyre char.

Well‐defined poly(N,N‐dimethylacrylamide) from a fast Cu(0)‐mediated reversible‐deactivation radical polymerization in water

AbstractCopper‐catalyzed reversible deactivation radical polymerization (RDRP) of N,N‐dimethylacrylamide (DMA) has been a significant challenge, particularly in aqueous environments, such as low yields, broad molecular weight distribution (MWD), and ill‐controlled molecular weights (MWs). In this work, we report the synthesis of well‐defined poly(N,N‐dimethylacrylamide) (PDMA) via a facile Cu(0)‐mediated RDRP in water. The results show that, unlike other acrylamide monomers, for DMA with abundant tertiary amide groups, the sufficient deactivation—the key to realizing control in copper‐catalyzed RDRP—cannot be simply fulfilled by just increasing the amount of deactivator (i.e., CuII species). The enhanced deactivation must be appropriately determined by also considering and selecting other reaction parameters. It is demonstrated that the use of methyl 2‐chloropropionate (MCP) as initiator and copper(II) chloride (CuCl2) as the additional catalyst is an effective combination to simultaneously enhance the deactivation control and facilitate the chain growth in aqueous Cu(0)‐mediated RDRP of DMA. This strategy successfully achieved the fast and well‐controlled synthesis of PDMAs with high monomer conversion, narrow MWDs, and a range of predefined MWs, and the well‐controlled in situ chain extensions.

Electrochemical Selenylation‐Induced Annulation of Alkenyl Ureas to Access Cyclic Isoureas

AbstractA direct electrosynthesis of cyclic isoureas from N‐allyl ureas and diselenides has been described. This protocol proceeds without any additional catalyst and oxidant, at room temperature under air, providing the desired products in 71–91% yield. In addition, the synthesis of cyclic isoureas containing five to seven‐membered rings has also been achieved by the employment of this strategy. On the basis of the mechanism experiments and previous research works, a probable mechanism is proposed.

Metal-Free Oxidative Formation of Aryl Esters by Catalytic Coupling of Acyl and Sulfonyl Chlorides with Arylboronic Acids.

A practical and efficient synthesis of aryl esters was developed through metal-free oxidation. This reaction employs stable and readily available acyl or sulfonyl chlorides and arylboronic acids as the starting materials and proceeds under mild reaction conditions without additional precious metal catalysts. This new strategy exhibits broad substrate tolerance and operational simplicity and gives diverse aryl esters in moderate to high yields.

Analysis of Factors Affecting the Preparation of Mullite Whiskers from Silica-Rich Slag and Application Studies.

This paper presents an in-depth comparative study of the effects of different molten salt systems, catalyst additions, preparation temperatures, temperature rise rates, and holding times on the properties of mullite whiskers during their preparation process, as well as exploring the enhancement of the toughening effect of mullite whiskers on ceramics. The morphology, crystal structure, and composition of the whiskers were analyzed via SEM, XRD, TG, strength tests, etc. The results show that the best-performing mullite whisker was prepared with an aluminum sulfate molten salt system, with the addition of aluminum fluoride catalyst at 4%, a temperature increase rate of 5 °C, a temperature increase up to 850 °C, and a holding time of 5 h, and its aspect ratio reached 20.64. By adding different contents of mullite whiskers and comparing the toughness strengths and wear rates of the silicon carbide ceramics, it was found that the toughness strength of the ceramics was improved by more than 16.5% and the wear rate was lower than 0.4% when the addition of mullite whisker was more than 3%.

Paper Waste Hydrolysis with Stepwise Sulfuric Acid Catalyst

The need for paper results in a lot of paper waste. Paper waste, which is lignocellulosic, can be hydrolyzed using an acid catalyst to produce various cellulose degradation products. In this study, the effect of the sulfuric acid catalyst addition method on the waste paper hydrolysis process was investigated. The addition of the catalyst was carried out in three types. The Type-1 method was sulfuric acid addition in the 0th minute. The Type-2 method was sulfuric acid addition in the 0th and 30th minutes. The Type-3 method was sulfuric acid addition every 10 minutes. The results showed that the lowest residual mass of waste paper hydrolyzed was produced using the Type-3 method. This showed that the Type-3 method, sulfuric acid addition every 10 minutes, had an effect on the residual mass of the hydrolyzed sample. The Type-3 method was the most effective type of sulfuric acid catalyst addition compared to other types. On the other hand, variations in the concentration of the sulfuric acid catalyst affect the residual mass of the waste paper hydrolyzed sample, where higher sulfuric acid concentration will lower residual mass. The catalyst concentration of 2% sulfuric acid with The Type-3 addition method resulted in the highest conversion which was 38.27%.

An ultrafast gelation based on catechol-metal ion dual self-catalysis used for 3D-printed dual-strain coaxial yarn

Hydrogels have achieved remarkable applications in intelligent sensing for their excellent performance. However, the traditional fabrication of such gels always requires a complex process with external stimuli, such as high-temperature and additional catalysts, bringing inconvenience and restrictions in broadscale application promotion. Hence, a novel and ultrafast self-catalysis initiation system is established by the special redox equilibrium among tannin acid (TA), iron (Fe3+) and ammonium persulphate (APS) with multi-functional capabilities. Based on it, a dual-train coaxial hydrogel yarn was manufactured by the selective coaxial ink 3D printing method, with excellent mechanical properties, temperature sensitivity and conductivity. The gelation time and mechanical properties of the hydrogel can be changed by adjusting the quality of Fe3+. Moreover, by introducing N-isopropyl acrylamide (NIPAM) with a lower critical solution temperature, the hydrogel yarn may be used to monitor the environmental temperature through the temperature-conductivity responsiveness, which implies their potential as smart materials for real-time temperature sensor.

Biochar production from the pyrolysis of food waste: Characterization and implications for its use

Food waste (FW) represents a large group of wastes that impose several issues on their management, especially in terms of microbiological and leaching pollution, and greenhouse gas emissions. According to the EU circular economy vision, finding a new way for FW valorisation to obtain reusable materials or compounds represents a priority. Thermal treatment represents one of the suitable ways for FW processing, and pyrolysis in particular presents many advantages in producing solid carbonaceous biochar, reusable oil and gas. This paper analyses biochar that was produced via thermal pyrolysis of FW. The influence of an organic additive (wooden sawdust) and a catalyst (zeolite) on the pyrolytic process at 600 °C was investigated. The results highlight how the initial composition of the feedstock (FS) influenced the characteristics of the obtained biochar. The addition of organic additives and catalyst did not change significantly the Brunauer–Emmett–Teller surface area and the calorific value. For all the analysed parameters, all tested FS respected the guidelines proposed by International Biochar Initiative (IBI) and the European Biochar Certificate (EBC) for possible reuse in agriculture and urban areas. The results suggest that biochar from FW could be potentially used in agriculture and urban green infrastructure, but the authors suggest further studies, especially on the effect of high electrical conductivity due to the typical high concentration of salts in FW.

Hierarchical Porous Bimetallic FeMn Metal-Organic Framework Gel for Efficient Activation of Peracetic Acid in Antibiotic Degradation.

Effective techniques for eliminating antibiotics from water environments are in high demand. The peracetic acid (PAA)-based advanced oxidation process has recently drawn increasing attention for its effective antibiotic degrading capability. However, current applications of PAA-based techniques are limited and tend to have unsatisfactory performance. An additional catalyst for PAA activation could provide a promising solution to improve the performance of PAA. Bulky metal-organic framework gels (MOGs) stand out as ideal catalysts for PAA activation owing to their multiple advantages, including large surface areas, high porosity, and hierarchical pore systems. Herein, a bimetallic hierarchical porous structure, i.e., FeMn13BTC, was synthesized through a facile one-pot synthesis method and employed for PAA activation in ofloxacin (OFX) degradation. The optimized FeMn MOG/PAA system exhibited efficient catalytic performance, characterized by 81.85% OFX degradation achieved within 1 h owing to the specific hierarchical structure and synergistic effect between Fe and Mn ions, which greatly exceeded the performance of the only PAA-catalyzed system. Furthermore, the FeMn MOG/PAA system maintained >80% OFX degradation in natural water. Quenching experiments, electron spin resonance spectra, and model molecular degradation revealed that the primary reactive oxygen species responsible for the catalytic effect was R-O•, especially CH3C(=O)OO•, with minor contributions of •OH and 1O2. Overall, introduction of the MOG catalyst strategy for PAA activation achieved high antibiotic degradation performance, establishing a paradigm for the design of heterogeneous hierarchical systems to broaden the scope of catalyzed water treatment applications.

Analysis Of Isothermal Pyrolysis Process Of Municipal Waste Into Bio-Oil With The Addition Of Natural Catalyst (Zeolite) In Supporting National Energy Security

Conversion technology will continue to evolve. These developments started from the industrial revolution 1.0 to the industrial revolution 4.0, but in these developments even though technology solves a problem, it has the potential to cause new problems such as environmental problems. Environmental problems that can occur starting from energy conversion that is not environmentally friendly as well as the use of several technologies that cause pollutants that are quite dangerous if high intensity can even cause health problems, acid rain and climate change. The pyrolysis process has been proven capable of converting municipal solid waste (SPP) into bio-oil (BO) where most of the BO produced is hydrocarbon fuel with light oil (naphtha) and diesel types. Many studies have been carried out by various groups, but the raw materials used are single SPP components such as plastic, biomass, tire rubber, paper and not the real SPP. Therefore, this research was conducted to see the effect of using variations in zeolite catalyst concentration on the bio-oil produced. Variations in zeolite catalyst concentration are divided into concentrations of 0.25; 0.5; 0.75 and 1. For the pyrolysis test, it was carried out at a temperature of 400 ° C, with a reaction time of 60 minutes. From the results of experiments that have been carried out, the most ideal concentration for producing the most bio-oil products is at a concentration of 0.5. This indicates that the more catalysts are used in the pyrolysis process, the more syngas products will be produced. So the use of catalysts in the pyrolysis process can increase thermal efficiency and the pyrolysis process can be carried out at low temperatures for the production of bio-oil from mixed waste. If following national oil needs and these reserves continue to be exploited, Indonesia will only have oil reserves for the next 7-8 years or until 2028. Another problem is that the use of conventional fuel oil will produce large amounts of CO2 and will make a major contribution to climate change and global warming.

Rice Malt: A Solvent-Catalyst for the Synthesis of N-Substituted Pyrroles

Aim: The synthesis of diverse N-substituted pyrroles utilizing rice malt is identified. The reaction of hexane-2,5-dione with various primary amines develops the intriguing pyrrole scaffold in moderate to good yields. Methods: The reaction was carried out at room to ambient temperature in an extremely environmentally benign condition, without the need for any additional solvents or catalysts. Results: In the synthesis of N-derivatized pyrroles, several 1 amines, both cyclic and acyclic residue, have been accomplished. Conclusion: To the best of my knowledge, no study has been reported so far based on Paal-Knorr pyrrole synthesis utilizing rice malt as a catalyst and solvent.

Optimization of hydrothermal carbonization of food waste as sustainable energy conversion approach: Enhancing the properties of hydrochar by landfill leachate substitution as reaction medium and acetic acid catalyst addition

Optimization of hydrothermal carbonization of food waste as sustainable energy conversion approach: Enhancing the properties of hydrochar by landfill leachate substitution as reaction medium and acetic acid catalyst addition

VA Home Telehealth Program for Initiating and Optimizing Heart Failure Guideline-Directed Medical Therapy.

Heart failure (HF) is a chronic, progressive medical condition. Evidence suggests that guideline-directed medical therapy improves both morbidity and mortality in patients with HF with reduced ejection fraction when properly optimized. Unfortunately, many patients do not receive optimized therapy, highlighting the need to optimize clinicians' methods to more effectively and efficiently initiate and titrate medical therapy. This single-center, retrospective study evaluated the rates of drug interventions prompted by the home telehealth monitoring program for veterans with HF with reduced ejection fraction. Rates of drug interventions were evaluated among those who enrolled and those who did not enroll in the program. There were 20 drug-related interventions in the home telehealth group compared with 11 interventions for the control group. One HF-related hospitalization occurred in the home telehealth program group compared with 6 in the control group. This study demonstrates the potential of home telehealth to optimize veterans' medication regimens and to reduce HF-related hospitalizations. It also provides an additional catalyst to further develop home telehealth services specifically targeted at drug therapy initiation and optimization in patients with HF with reduced ejection fraction.

Tetrameric cubane Al 9Ln 7 (Ln = Ce, Pr, Nd) clusters as aldol addition catalysts

Tetrameric cubane Al ₉Ln ₇ (Ln = Ce, Pr, Nd) clusters as aldol addition catalysts

Interfacial nanoarchitectonics of nickel phosphide supported on activated carbon for transfer hydrogenation of nitroarenes under mild conditions

Metal phosphides are promising catalysts for hydrogenation reactions due to their unique ability to generate active hydrogen species which are essential for desired reactions. In this work, the hydrogenation potential of nickel phosphide (Ni2P) is explored for the transfer hydrogenation of aromatic nitro compounds using hydrazine hydrate as hydrogen source. The Ni2P was supported on activated carbon (AC) to facilitate highly exposed active reaction sites. The as-synthesized Ni2P-AC catalyst showed excellent catalytic potential for the hydrogenation of nitro compounds to corresponding amines with 100% conversion efficiency and resulted in excellent yields. The reaction conditions were optimized by varying different reaction parameters, such as time, temperature, solvents, catalyst amount and hydrogen sources. The developed reaction protocol is highly selective for nitro compounds having reduction susceptible functional groups like -Cl, -Br, –CHO, etc. The structure–activity relationship of the Ni2P-AC was also examined which suggested that both acidic and basic sites present in Ni2P-AC catalyst plays crucial role in hydrogenation reaction. Besides, an in-depth insight into the reaction mechanism illustrates that the reaction proceeds via N-phenyl hydroxylamine as the reaction intermediate. In addition, decent recyclability and stability of Ni2P-AC catalyst demonstrates its highly versatile nature for potential large-scale applications. The use of highly efficient Ni2P-AC catalyst for hydrogenation reactions can lead the way towards sustainable and effective industrial organic catalysis.

Core-dependent post-translational modifications guide the biosynthesis of a new class of hypermodified peptides

The ribosomally synthesized and post-translationally modified peptide (RiPPs) class of natural products has undergone significant expansion due to the rapid growth in genome sequencing data. Using a bioinformatics approach, we identify the dehydrazoles, a novel class of hypermodified RiPPs that contain both side chain dehydration of Ser residues, and backbone heterocyclization at Ser, Thr, and Cys residues to the corresponding azol(in)es. Structure elucidation of the hypermodified peptide carnazolamide, a representative class member, shows that 18 post-translational modifications are installed by just five enzymes. Complete biosynthetic reconstitution demonstrates that dehydration is carried out by an unusual DUF4135 dehydration domain fused to a zinc-independent cyclase domain (CcaM). We demonstrate that CcaM only modifies Ser residues that precede an azole in the core peptide. As heterocyclization removes the carbonyl following the Ser residue, CcaM likely catalyzes dehydration without generating an enolate intermediate. Additionally, CcaM does not require the leader peptide, and this core-dependence effectively sets the order for the biosynthetic reactions. Biophysical studies demonstrate direct binding of azoles to CcaM consistent with this azole moiety-dependent dehydration. Bioinformatic analysis reveals more than 50 related biosynthetic gene clusters that contain additional catalysts that may produce structurally diverse scaffolds.

Photocatalytic Scheme with External Magnetic Field on Coffee Waste in Hydrogen Production

Photocatalytic is considered a deadlock-breaking technology for renewable energy and lowering environmental pollutants. Photocatalytic efficiency efforts are improved by activating the photocatalyst to introduce an external magnetic field. This review highlights recent breakthroughs by comparing original coffee waste, activation of coffee waste with the addition of catalysts, and manipulation of spin electrons by applying external magnets. Characterization was done with FTIR to look at chemical bonds, UV-Vis with Tauc's Relation approach to measure bandgap, and material morphology using SEM EDX. The increase in photocatalyst activation aligns with the decrease in bandgap value. The rate of decline in bandgap is in line with the rate of acceleration of hydrogen production. Adding an external magnetic increases hydrogen production up to 1.5 times greater than the original photocatalytic.

The ionic liquids upon perchlorate to promote the C-C/C-O bonds cleavage in alkali lignin under photothermal synergism

Transforming lignin into aromatic monomers is critically attractive to develop green and sustainable energy supplies. However, the usage of the additional catalysts like metal or base/acid is commonly limited by the caused repolymerized and environmental issues. The key step is to mediate electron transfer in lignin to trigger lignin C-C/C-O bonds cleavage without the catalysts mentioned above. Here, we report that the ionic liquids [BMim][ClO4] was found to trigger lignin electron transfer to cleave the C-C/C-O bonds for aromatic monomers without any additional catalyst. The proton transfer from [BMim]+ to [ClO4]− could polarize the anion and decrease its structure stability, upon which the active hydroxyl radical generated and induced lignin C-C/C-O bonds fragmentation via free radical-mediated routes with the assistance of photothermal synergism. About 4.4 wt% yields of aromatic monomers, mainly composed of vanillin and acetosyringone, are afforded in [BMim][ClO4] under UV-light irradiation in the air at 80 °C. This work opens the way to produce value-added aromatic monomers from lignin using an eco-friendly, energy-efficient, and simple route that may contribute to the sustainable utilization of renewable natural resources.

Catalytic steam gasification of bituminous coal for syngas production with catalyst derived from calcium-rich construction demolition waste

A disposable Ca-containing catalyst was generated from a sort of calcium-rich construction demolition waste and utilized in the steam gasification of a bituminous coal in a fixed bed reactor. The effects of catalyst loading amount, gasifying temperature and catalyst loading method on steam gasification with respect to the production of syngas with high H2/CO mole ratio and CH4 content were investigated. The H2 and CO molar yields as well as carbon conversion increased noticeably with the increase of catalyst loading amount despite there was a saturation quantity. After loading 6.0 wt% catalyst into coal by kneading method, the carbon conversion and total gas molar yield increased from 52.56% and 136.06 mmol/g-C to 62.77% and 160.23 mmol/g-C, respectively. At low temperature, kneading method displayed superiority over mechanical mixing method in steam gasification performance of bituminous coal while they had approximately the same catalytic effect on coal steam gasification at high temperature. Characterization of SEM images and Raman spectroscopy of coal chars derived from catalytic pyrolysis confirmed that addition of catalyst changed the micro-crystal structure and formed more defects and amorphous structures. Overall, the catalyst showed satisfactory catalytic effect in steam gasification of bituminous coal and could be used as a suitable alternative of CaO for syngas production.

Catalytic stepwise pyrolysis for dechlorination and chemical recycling of PVC-containing mixed plastic wastes: Influence of temperature, heating rate, and catalyst

The viability of pyrolysis technology for chemical recycling of plastics is challenged by the presence of PVC in real-world mixed plastic wastes. This study aims to investigate catalytic stepwise pyrolysis as a pretreatment step to remove chlorine from PVC-containing plastic wastes prior to further processing. TG-FTIR and Py-GCMS analysis as well as experiments on a lab-scale pyrolysis system were conducted to study the influence of key processing parameters on the pretreatment including temperature, heating rate, and catalysts. Py-GCMS results indicated 300 °C to be the best pretreatment temperature in terms of balancing Cl removal and avoidance of organochloride formation. Metal oxides, i.e., CaO and Fe2O3, mainly acted as adsorbents of HCl gases with little cracking effect, and their adsorption effects are positively correlated with alkalinity. ZSM-5 catalysts promoted the release of HCl, and the dechlorination effect was more pronounced with ZSM-5 of higher acidity. In contrast, in the lab-scale pyrolysis system, 350 °C pretreatment achieved the highest HCl generation ratio, i.e., 43.60 %. The addition of zeolite catalyst significantly reduced the content of organochloride in the pyrolysis oil in contrast to the performance of metal oxides, but also absorbed most HCl instead of promoting HCl release as in Py-GCMS tests. Mass balance analyses revealed that the majority of chlorine was retained in the solid residues following the catalytic stepwise pyrolysis process, with the notable exception of Fe2O3. ZSM-5(25) catalyst combined with 350 °C pretreatment temperature and 550 °C final pyrolysis achieved the lowest chlorine content in the pyrolysis oil, i.e., 20 ppm, among different process conditions.