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Catalytic Valorisation of Biomass-Derived Levulinic Acid to Biofuel Additive γ-Valerolactone: Influence of Copper Loading on Silica Support 生物质衍生乙酰丙酸对生物燃料添加剂γ-戊内酯的催化增值:铜负载对二氧化硅载体的影响
Pub Date : 2023-09-05 DOI: 10.3390/reactions4030028
Rajender Boddula, Paramasivam Shanmugam, Rajesh K. Srivatsava, Nabila Tabassum, Ramyakrishna Pothu, R. Naik, Aditya Saran, B. Viswanadham, A. B. Radwan, N. Al-Qahtani
γ-valerolactone (GVL) is a crucial chemical feedstock used in the production of fuel additives, renewable fuels, and fine chemicals alternative to petroleum-based solvents and chemicals, supporting the transition to sustainable energy solutions. It is promptly acquired by hydrogenating levulinic acid (LA) in a gaseous or liquid phase with a homogeneous or heterogeneous catalyst using a variety of recognized catalytic processes. Herein, this work focuses on the use of silica-supported copper (Cu/SiO2) catalysts for the gas-phase hydrogenation of LA to GVL under mild reaction conditions. The study analyzes how copper loading can affect the catalytic activity of the Cu/SiO2, while the flow rate of LA, time-on-stream, reaction temperature, and LA concentration affect the catalytic efficiency. The SiO2 support’s various Cu loadings are crucial for adjusting the catalytic hydrogenation activity. One of the studied catalysts, a 5 wt% Cu/SiO2 catalyst, demonstrated ~81% GVL selectivity with ~78% LA conversion and demonstrated stability for ~8 h while operating at atmospheric pressure and temperature (265 °C) and 0.5 mL/h of LA flow rate. The ability to activate hydrogen, high amount of acidic sites, and surface area were all discovered to be advantageous for increased GVL selectivity.
γ-戊内酯(GVL)是一种重要的化学原料,用于生产燃料添加剂、可再生燃料和精细化学品,以替代石油基溶剂和化学品,支持向可持续能源解决方案的过渡。它是通过使用各种公认的催化过程,用均相或多相催化剂在气相或液相中加氢乙酰丙酸(LA)而迅速获得的。本文主要研究了在温和反应条件下,利用二氧化硅负载铜(Cu/SiO2)催化剂催化LA气相加氢制GVL。研究分析了载铜量对Cu/SiO2催化活性的影响,LA流量、流时间、反应温度和LA浓度对催化效率的影响。SiO2载体的各种Cu负载对调节催化加氢活性至关重要。其中一种催化剂,5 wt% Cu/SiO2催化剂,具有~81%的GVL选择性和~78%的LA转化率,并且在常压、常温(265℃)和0.5 mL/h LA流速下稳定运行~8 h。活化氢的能力、大量的酸性位点和表面积都被发现有利于提高GVL的选择性。
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引用次数: 1
One-Pot Synthesis of Stable Poly([c2]Daisy–chain Rotaxane) with Pseudo-Stopper via Metathesis Reaction and Thiol-Ene Reaction 通过复分解反应和巯基烯反应一锅合成具有伪塞的稳定聚([c2]菊链轮烷)
Pub Date : 2023-08-23 DOI: 10.3390/reactions4030027
Risako Kamoto, K. Onimura, K. Yamabuki
Rotaxanes, known as supramolecular compounds, are expected to find applications in functional materials due to their high degree of freedom. However, their synthesis requires multistep reactions, and there is a demand for more convenient methods to synthesize rotaxane materials. In this study, we aimed to investigate a simpler method for synthesizing highly functional rotaxane materials and explore the diversity of molecular designs. To achieve this, we successfully synthesized a host–guest conjugated compound that incorporates both crown ether as the host unit and secondary ammonium salts as the guest unit within the same molecule. Subsequently, the metathesis reaction of these compounds, which construct [c2]daisy-chain rotaxanes, enabled the one-pot synthesis of a topological polymer called “poly([c2]daisy-chain rotaxane)” with a pseudo-stopper. This methodology achieves the stabilization and polymerization of rotaxanes simultaneously, contributing to the easy materialization of rotaxanes. Furthermore, the thiol-ene reaction achieved the extension of the distance between rotaxane units and provided a useful approach to diversify the design of functional materials with rotaxane structures.
轮烷被称为超分子化合物,由于其高度的自由度,有望在功能材料中找到应用。然而,它们的合成需要多步反应,需要更方便的方法来合成轮烷材料。在本研究中,我们旨在探索一种更简单的方法来合成高功能轮烷材料,并探索分子设计的多样性。为了实现这一目标,我们成功地合成了一种主客体共轭化合物,该化合物在同一分子内将冠醚作为宿主单位和仲铵盐作为客体单位。随后,这些化合物的复合反应,构建了[c2]雏菊链轮烷,使得一锅合成一种具有伪塞的拓扑聚合物“聚([c2]雏菊链轮烷)”成为可能。该方法同时实现了轮烷的稳定和聚合,有利于轮烷的物化。此外,巯基烯反应实现了轮烷单元之间距离的延长,为具有轮烷结构的功能材料的多样化设计提供了有益的途径。
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引用次数: 0
Various Techniques for the Synthesis of 2-Nitrophenylamino-1,4-naphthoquinone Derivatives 2-硝基苯胺-1,4-萘醌衍生物的各种合成技术
Pub Date : 2023-08-21 DOI: 10.3390/reactions4030026
E. Leyva, Silvia E. Loredo-Carrillo, Johana Aguilar
Nitrated products are important since they are intermediates in the synthesis of other compounds, such as explosives, perfumes, dyes and plastics, among others, and they have an easy capacity to convert into other functional groups. The synthesis of compounds with biological activity that have a nitro group in their structure is relevant to improving and/or enhancing their effect. In this work, different methodologies for the nitration of naphthoquinone derivative compounds are presented. The nitration of 3-R-2-(phenylamino)-1,4-naphthoquinone derivatives was carried out with nitric acid and sulfuric acid; milder reaction conditions were also established by diluting the acids or performing the reaction with weaker acids. Other methodologies were tested using nitrate salts for mononitrate product synthesis. We used a solvent-free reaction with oxalic acid using 3-R-2-(phenylamino)-1,4-naphthoquinones (R=H, Br or Cl), noting that the electronegativity of the chlorine group is decisive for achieving nitration with good yields. Finally, a Michael addition was performed with some nitrated anilines. To obtain denitrated compounds in the ortho and para positions, the reaction with strong acids is feasible; however, for the formation of mononitrated products, the Michael-type addition is more convenient.
硝化产物很重要,因为它们是合成其他化合物(如炸药、香水、染料和塑料等)的中间体,而且它们很容易转化为其他官能团。结构中含有硝基的具有生物活性的化合物的合成与改善和/或增强其作用有关。本文介绍了萘醌衍生物的不同硝化方法。用硝酸和硫酸对3-R-2-(苯胺)-1,4-萘醌衍生物进行硝化反应;通过稀释酸或用较弱的酸进行反应,也建立了较温和的反应条件。用硝酸盐合成单硝酸盐产品测试了其他方法。我们使用3-R-2-(苯胺)-1,4-萘醌(R=H, Br或Cl)与草酸进行无溶剂反应,注意到氯基团的电负性是实现高收率硝化的决定性因素。最后,用一些硝化苯胺进行迈克尔加成。为了得到邻位和对位的脱硝化合物,强酸反应是可行的;而对于单硝化产物的形成,michael型加成更为方便。
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引用次数: 0
Insight into the Physicochemical Properties of Co-Based Catalysts in Fischer–Tropsch Synthesis 费托合成中co基催化剂的物理化学性质研究
Pub Date : 2023-08-04 DOI: 10.3390/reactions4030025
Nothando C. Shiba, Xinying Liu, Yali Yao
The effect of the different supports and catalyst-reducing agents on the Fischer–Tropsch (FT) reaction was investigated. The large surface area SiO2 support with a smaller pore volume deposited fine, evenly distributed Co3O4. Cubic-shaped Co3O4 appeared in clusters on the TiO2 support, whereas Co3O4 existed as single large particles on the Al2O3 support. The activity data obtained were discussed in terms of cluster size, particle size, particle shape, and mass transport limitations. The SiO2-supported catalysts showed a higher activity for the formation of paraffinic products when reduced in H2 at 250 °C. This is attributed to the formation of the CoO-Co active bond, which enhanced the activation of CO and the hydrogenation reactions. A higher activity was observed for the TiO2-supported catalyst at a higher reduction temperature (350 °C) when the mass of Co metal was higher. It afforded more paraffinic products due to enhanced secondary hydrogenation of olefins at higher reaction rates. The large Co3O4 supported on Al2O3 showed the least activity at both reduction temperatures due to strong metal-support interactions. The H2-reduced catalysts exhibited superior activity compared to all the syngas-reduced catalysts. Syngas reduction led to surface carbon deposition and the formation of surface carbides which suppressed the hydrogenation reactions and are selective to olefinic products.
研究了不同载体和还原剂对费托反应的影响。孔隙体积小、表面积大的SiO2载体沉积了细小、均匀的Co3O4。Co3O4在TiO2载体上呈立方状簇状存在,而在Al2O3载体上呈单个大颗粒存在。得到的活性数据从簇大小、颗粒大小、颗粒形状和质量输运限制等方面进行了讨论。sio2负载型催化剂在250℃的H2还原条件下,具有较高的石蜡产物生成活性。这是由于CO - CO活性键的形成,增强了CO的活化和加氢反应。在较高的还原温度(350℃)下,tio2负载型催化剂的活性越高,Co金属质量越高。在较高的反应速率下,烯烃的二次加氢反应增强,从而产生更多的石蜡产物。在两种还原温度下,由Al2O3支撑的大Co3O4表现出最低的活性,这是由于强的金属-载体相互作用。h2还原催化剂的活性优于所有合成气还原催化剂。合成气还原导致表面碳沉积和表面碳化物的形成,抑制了加氢反应,对烯烃产物有选择性。
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引用次数: 0
Kinetics and Mechanism of Electrochemical Reactions Occurring during the Chromium Electrodeposition from Electrolytes Based on Cr(III) Compounds: A Literature Review 基于Cr(III)化合物的电解液电沉积铬的电化学反应动力学和机理:文献综述
Pub Date : 2023-08-03 DOI: 10.3390/reactions4030024
V. Protsenko
A literature review was conducted to examine the current understanding of the kinetics and mechanism of electrochemical reactions occurring during the electrodeposition of chromium coatings from electrolytes based on trivalent chromium compounds. The research in this scientific field is crucial, as it addresses the pressing need for an alternative to chromium plating processes that rely on solutions containing highly toxic and harmful hexavalent chromium compounds. Numerous literature data on the kinetics and mechanism of the stepwise reduction process of Cr(III) complex ions were analyzed. The influence of various additives and surfactants on the reaction kinetics of the stepwise reduction of trivalent chromium ions was considered. Special attention was given to the kinetics of the stepwise discharge of trivalent chromium ions in ionic liquids and deep eutectic solvents.
本文综述了目前对三价铬化合物电解质电沉积铬涂层过程中电化学反应的动力学和机理的理解。这一科学领域的研究是至关重要的,因为它解决了迫切需要一种替代镀铬工艺的方法,这种工艺依赖于含有剧毒和有害的六价铬化合物的溶液。分析了Cr(III)络合物离子逐步还原过程的动力学和机理。研究了各种添加剂和表面活性剂对三价铬离子分步还原反应动力学的影响。特别注意了三价铬离子在离子液体和深共晶溶剂中逐步放电的动力学。
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引用次数: 1
The Formation of Small Amounts of Cyclopropane during Pulsed Pyrolysis of C4–C5 Acyclic Alkanes in the Adiabatic Compression Reactor 绝热压缩反应器中C4-C5无环烷烃脉冲热解过程中少量环丙烷的生成
Pub Date : 2023-07-19 DOI: 10.3390/reactions4030023
I. Bilera
During high-temperature pulse pyrolysis of acyclic butanes and pentanes under adiabatic compression conditions, cyclopropane, a stressed cyclic hydrocarbon, was found among the reaction products in small quantities for the first time. The analysis of the reaction products was performed by gas chromatography using three capillary columns of different polarity, selectivity and sufficient efficiency. The identification of reaction products, including cyclopropane, was performed using retention times of individual substances and model mixtures, as well as comparing chromatograms with reference chromatograms from the literature and the ScanView Application Database. It was shown that the chromatographic peak attributed to cyclopropane could not be a ghost peak. Additional confirmation of this conclusion was obtained in a series of experiments on the pyrolysis of n-butane at a reduced initial temperature of the adiabatic compression reactor (from 120 °C to 50 °C) and a modified mode of GC analysis. Cyclopropane yields as a function of maximum temperature have a bell-shaped asymmetric dependence. The maximum value of the yield of cyclopropane increases with the transition from normal alkanes to isoalkanes, and from pentanes to butanes; for n-pentane, 0.009 wt. %, and for isobutene, ≈0.017 wt. %. During the pulse pyrolysis of isobutane, n-butane, isopentane and n-pentane, cyclopropane is not a primary product. Further theoretical and experimental studies are needed to establish the mechanism of cyclopropane formation during pyrolysis of C4–C5 acyclic alkanes.
在绝热压缩条件下对无环丁烷和戊烷进行高温脉冲热解时,首次在反应产物中少量发现了应力环烃环丙烷。用三根极性、选择性和效率不同的毛细管柱对反应产物进行气相色谱分析。通过单个物质和模型混合物的保留时间,以及将色谱图与文献和ScanView应用数据库中的参考色谱图进行比较,对包括环丙烷在内的反应产物进行了鉴定。结果表明,环丙烷色谱峰不可能是鬼峰。通过降低绝热压缩反应器初始温度(从120℃降至50℃)和改进的GC分析模式对正丁烷的热解进行了一系列实验,进一步证实了这一结论。环丙烷产率与最高温度呈钟形不对称关系。环丙烷产率最大值随着正构烷烃向异构烷烃、戊烷向丁烷的过渡而增大;正戊烷≈0.009 wt. %,异丁烯≈0.017 wt. %。在异丁烷、正丁烷、异戊烷和正戊烷的脉冲热解过程中,环丙烷不是主要产物。C4-C5无环烷烃热解生成环丙烷的机理有待进一步的理论和实验研究。
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引用次数: 0
Zeolite-Containing Co Catalysts for Fischer–Tropsch Synthesis with Tailor-Made Molecular-Weight Distribution of Hydrocarbons 含Co分子筛的费托合成催化剂及其对烃类分子质量的影响
Pub Date : 2023-07-15 DOI: 10.3390/reactions4030022
L. Sineva, V. Mordkovich, E. Asalieva, V.Ye. Smirnova
The review is dedicated to the topical field of research aimed at creating catalysts combining several types of active sites. At the same time, the composition of Fischer–Tropsch synthesis (FTS) products can be controlled by changing the strength and concentration of the active sites and inter-site distances. A comparative analysis of the literature data allows to formulate the main principles of catalytic particles formation active in FTS and acid-catalyzed transformations of hydrocarbons: (1) the presence of weak Bronsted acid sites to control the cracking depth, (2) an availability of Bronsted acid sites for re-adsorption hydrocarbons and (3) weak Co-zeolite interaction to reduce methane formation.
该综述致力于研究旨在创造结合几种类型活性位点的催化剂的主题领域。同时,可以通过改变活性位点的强度和浓度以及位点间距离来控制费托合成产物的组成。通过对文献数据的对比分析,可以得出催化颗粒形成在FTS和酸催化烃类转化中活跃的主要原理:(1)弱Bronsted酸位点的存在控制裂解深度;(2)对烃类再吸附的Bronsted酸位点的可用性;(3)弱co -沸石相互作用减少甲烷生成。
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引用次数: 1
Okra Micro-Cellulose Crystal (MCC) and Micro-Clay Composites for the Remediation of Copper, Nickel, and Dye (Basic Yellow II) from Wastewater 秋葵微纤维素晶体(MCC)和微粘土复合材料对废水中铜、镍和染料(碱性黄II)的修复研究
Pub Date : 2023-07-04 DOI: 10.3390/reactions4030021
A. A. Mohana, M. Rahman, Md. Hafezur Rahaman, M. Maniruzzaman, S. Farhad, Md Meftaul Islam, Md. Sirajul Islam Khan, Md. Zahid Parvez
Water pollution by contaminants such as toxic metals and dyes is now a major concern due to their high toxicity and persistence in the environment. Advances in nanotechnology have enabled the use of micro/nanomaterials to treat and purify water in various industries. In this study, Bijoypur clay was modified with ethyldiamine and incorporated into an okra fiber (Abelmoschus esculentus) micro-cellulose crystal (MCC) to produce a composite that could absorb copper (Cu), nickel (Ni), and dyes like basic yellow (II) from industrial wastewater. Composites were prepared using different percentages of MCC and clay. Atomic absorption spectroscopy (AAS) was used to determine the concentrations of Cu and Ni whereas a UV–Visible spectrophotometer measured the absorbance of basic yellow (II). The synthesized composites were extensively characterized using a range of techniques including thermogravimetry (TG) and differential thermogravimetry (DTG), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Results show that both the MCC and clay could absorb Cu, Ni, and basic yellow (II) from the contaminated wastewater. The MCC and clay composite showed the maximum efficiency of metals removal, which was up to 95% (24 mg/g) for Cu at pH 6, 20 min contact time, 2 g/L adsorbent dose, and 100% (31 mg/g) for Ni at pH 8, 60 min contact time, and 2 g/L adsorbent dose, respectively, at the initial concentration of 50 mg/L. The maximum dye uptake capacity of 85% (19 mg/g) was observed by the MCC and clay composite under optimized conditions at the initial concentration of 50 mg/L, pH 8, 30 min contact time, and 1 g/L adsorbent dose compared to the pure clay, which had an efficiency up to 26% for Cu and 24% for dye removal. All of the results indicate that incorporating clay into MCC increases the absorption capacity of contaminants from wastewater, which could be more effective for environmental applications compared to untreated cellulose.
由于有毒金属和染料等污染物的高毒性和在环境中的持久性,水污染现在是一个主要问题。纳米技术的进步使微/纳米材料能够在各种工业中处理和净化水。在这项研究中,Bijoypur粘土用乙二胺改性,并加入到秋葵纤维(Abelmoschus esculentus)微纤维素晶体(MCC)中,生产出一种复合材料,可以吸收工业废水中的铜(Cu)、镍(Ni)和碱性黄(II)等染料。采用不同比例的MCC和粘土制备复合材料。原子吸收光谱(AAS)测定了Cu和Ni的浓度,紫外可见分光光度计测定了碱性黄(II)的吸光度。利用热重法(TG)和差热重法(DTG)、傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)和x射线衍射(XRD)等一系列技术对合成的复合材料进行了广泛的表征。结果表明,MCC和粘土均能吸附废水中的Cu、Ni和碱性黄(II)。MCC和粘土复合材料对金属的去除率最高,当pH为6、接触时间为20 min、吸附剂剂量为2g /L时,Cu的去除率为95% (24 mg/g);当pH为8、接触时间为60 min、吸附剂剂量为2g /L时,Ni的去除率为100% (31 mg/g),初始浓度为50 mg/L。在初始浓度为50 mg/L、pH为8、接触时间为30 min、吸附剂剂量为1 g/L的条件下,与纯粘土相比,MCC和粘土复合材料对染料的最大吸收率为85% (19 mg/g),对铜的去除率为26%,对染料的去除率为24%。所有结果表明,在MCC中加入粘土增加了对废水中污染物的吸收能力,与未经处理的纤维素相比,这可能更有效地用于环境应用。
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引用次数: 1
BCG vaccine 卡介苗
Pub Date : 2023-07-01 DOI: 10.1007/s40278-023-42179-7
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引用次数: 0
Nitrous oxide 一氧化二氮
Pub Date : 2023-07-01 DOI: 10.1007/s40278-023-43353-2
{"title":"Nitrous oxide","authors":"","doi":"10.1007/s40278-023-43353-2","DOIUrl":"https://doi.org/10.1007/s40278-023-43353-2","url":null,"abstract":"","PeriodicalId":20873,"journal":{"name":"Reactions","volume":"54 1","pages":"10"},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91144299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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