DOCSLIB.ORG

Tailoring the Surface Area and the Acid–Base Properties of Zro2 for Biodiesel Production from Nannochloropsis Sp

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Tailoring the Surface Area and the Acid–Base Properties of Zro2 for Biodiesel Production from Nannochloropsis Sp www.nature.com/scientificreports OPEN Tailoring the surface area and the acid–base properties of ZrO2 for biodiesel production from Nannochloropsis sp. Nurul Jannah Abd Rahman1, Anita Ramli1*, Khairulazhar Jumbri1,3 & Yoshimitsu Uemura2,3 Bifunctional heterogeneous catalysts have a great potential to overcome the shortcomings of homogeneous and enzymatic catalysts and simplify the biodiesel production processes using low-grade, high-free-fatty-acid feedstock. In this study, we developed ZrO2-based bifunctional heterogeneous catalysts for simultaneous esterifcation and transesterifcation of microalgae to biodiesel. To avoid the disadvantage of the low surface area of ZrO2, the catalysts were prepared via a surfactant-assisted sol-gel method, followed by hydrothermal treatments. The response surface methodology central composite design was employed to investigate various factors, like the surfactant/ Zr molar ratio, pH, aging time, and temperature on the ZrO2 surface area. The data were statistically analyzed to predict the optimal combination of factors, and further experiments were conducted for verifcation. Bi2O3 was supported on ZrO2 via the incipient wetness impregnation method. The catalysts were characterized by a variety of techniques, which disclosed that the surfactant-assisted ZrO2 nanoparticles possess higher surface area, better acid–base properties, and well-formed pore structures than bare ZrO2. The highest yield of fatty acid methyl esters (73.21%) was achieved using Bi2O3/ ZrO2(CTAB), and the catalytic activity of the developed catalysts was linearly correlated with the total densities of the acidic and basic sites. The mechanism of the simultaneous reactions was also discussed. Biodiesel is an attractive alternative source of energy owing to its renewability, biodegradability, sustainability, and non-toxicity1. It is produced by transesterifcation of vegetable oil or animal fat with short-chain alcohols in the pres- ence of suitable chemical catalysts (homogeneous/heterogeneous) or enzymatic biocatalysts2–4. Today, there has been growing research interest in using microalgae as biodiesel feedstock because of its rapid growth rate, high photosyn- thetic efciency, and high oil contents, as well as the minimum space needed for cultivation5,6. Industrially, conven- tional homogeneous catalysts are used in the transesterifcation process for the production of biodiesel2. However, the catalysts require extensive washing and purifcation steps, and they cause undesired saponifcation when dealing with high-free-fatty-acid (FFA) content feedstock7. Te enzymatic transesterifcation of lipases is commonly associated with high production cost and fast deactivation at severe reaction conditions that limit its application at an industrial scale8. An alternative method to overcome these challenges is the utilization of heterogeneous catalysts. Numerous studies have been reported on heterogeneous catalysis for biodiesel production. Te most common key features of efcient and active heterogeneous transesterifcation catalysts are high surface area9,10, adequate acidic11–13 and basic14–17 densities, good crystallinity14, and -well-formed pore structure10,12,13. Recent developments in this feld have led to renewed interest in bifunctional acid–base heterogeneous catalysts for simultaneous esterif- cation and transesterifcation of low-grade high-FFA model feedstock7,18,19, such as microalgae lipid. Heterogeneous acidic catalysts are commonly used for the esterifcation step as the reaction is less afected by the presence of water and FFA. Instead, heterogeneous basic catalysts are employed in the second transesterifcation step because they are more active than acidic catalysts, which require shorter reaction time and lower reaction temperature20. Some stud- ies have reported the use of bifunctional heterogeneous catalyst for biodiesel production18,19,21–23. However, reports on their application using microalgae lipid as the biodiesel feedstock are still limited. 1Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS, 32610, Seri Iskandar, Perak, Malaysia. 2Centre for Biofuel and Biochemical Research, Universiti Teknologi PETRONAS, 32610, Seri Iskandar, Perak, Malaysia. 3These authors contributed equally: Khairulazhar Jumbri and Yoshimitsu Uemura. *email: [email protected] SCIENTIFIC REPORTS | (2019) 9:16223 | https://doi.org/10.1038/s41598-019-52771-9 1 www.nature.com/scientificreports/ www.nature.com/scientificreports Zirconium dioxide (zirconia, ZrO2) is a well-known heterogeneous catalyst and catalyst support that exhibits unique characteristic of amphoteric nature which indicates its remarkable potential to perform simultaneous 19 esterifcation–transesterifcation reactions of high-FFA feedstock to biodiesel . ZrO2 has a high boiling point, high melting point, good thermal stability, and good corrosion resistance, making it an excellent heterogeneous 24,25 catalyst even under harsh reaction conditions . As a catalyst support, ZrO2 exhibits better chemical properties and higher stability than the traditional catalyst supports of γ-alumina and silica26. Among the common tech- 27,28 24,29 30 31,32 niques of synthesizing ZrO2 are sol-gel , precipitation , microwave-assisted , ultrasound-assisted , and emulsion33 methods. However, one of the biggest challenges that has limited its performance in practical applica- 24 tions so far is the development of a suitable synthetic route of ZrO2 with a high surface area, adequate acid–base properties, good crystalline structure, and well-developed porosity for the aforementioned purpose. Several attempts have been adopted to improve the surface area of heterogeneous catalysts through the syn- thesis of nanoscale materials by surfactant-assisted methodologies34,35. Te surfactant plays a decisive role in tailoring the properties of the heterogeneous catalysts, including its shape and size, which, in turn, depend on the nature of the surfactant, such as the length of the hydrophobic tail and the ions (cationic, anionic, or non-ionic) 36. Previous studies suggested the use of surfactant in the sol-gel technique because of its homogeneity and abil- ity to control the surface area, the pore volume, and the pore size distribution of the catalysts31,37. Te synthe- sis of surfactant-assisted ZrO2 catalyst is governed by a variety of parameters, including the surfactant type and the synthetic conditions that afect its overall quality. For instance, Eltejaei et al. used poly(ethylene gly- col)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG–PPG–PEG) as a non-ionic surfactant in the 34 synthesis of tetragonal ZrO2, employing the precipitation method at basic Ph . Alteration of the pH from 10 to 11 resulted in high surface area ZrO2 due to the increase in surface charge and nucleation that occurs at high pH values. In another study, Zhang et al. synthesized nano-sized tetragonal ZrO2 via hydrothermal treatment using cetrimonium bromide (CTAB) as the cationic surfactant. Hydrothermal energy, a non-conventional energy source for the synthesis of nanoparticles, prevents particle agglomeration and allows for uniform grain size and regular morphology38. In the present study, we developed an efective ZrO2-based bifunctional heterogeneous catalyst for simulta- neous esterifcation–transesterifcation of microalgae lipid to biodiesel. Te efect of several process parameters on the surface area of ZrO2 prepared by a surfactant-assisted sol-gel method followed by a hydrothermal treat- ment using non-ionic and cationic surfactants under basic conditions was investigated. Te optimization of the process parameters was achieved using response surface methodology central composite design (RSMCCD). Mathematical models were developed and validated to predict the maximum surface area of ZrO2. Te acidic and basic properties of ZrO2 were tailored afer modifcation with bismuth oxide (Bi2O3) via incipient wetness impregnation method. Te synthesized catalysts were found to be active towards the conversion of microalgae lipid to biodiesel. Results and Discussion Efect of the type of the surfactants and the reaction parameters on the surface area of ZrO 2 and optimization study. The maximum surface area of ZrO2 was achieved using poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic P123) and cetrimonium bromide (CTAB) as surfactants, yielding the ZrO2(P123) and ZrO2(CTAB) catalysts, respectively. Te optimization of the pro- cess parameters was conducted by employing RSMCCD, which maintained the experimental conditions within the desired range of independent parameters. According to the literature, the most important parameters afect- 39,40,41 ing the surface area of ZrO2 are the surfactant/Zr ratio (A), pH (B), aging time (C), and temperature (D) . Te specifc values of the independent parameters used in this study, along with the surface area obtained for ZrO2(P123) and ZrO2(CTAB) are cited in Supplementary Tables S1 and S2, respectively. Specifcally, among the 2 30 experimental RSMCCD runs, ZrO2(P123) displayed a maximum surface area of 79 m /g (Run 21), whereas 2 ZrO2(CTAB) exhibited a maximum surface area of 295 m /g (Run 20). Te relationship between the independent parameters and the surface area obtained using the analysis of variance (ANOVA) test for ZrO2(P123) and ZrO2(CTAB) are summarized in Supplementary Tables S3 and S4, respectively. By ftting the data to various polynomial models, the ANOVA result shows that both ZrO2(P123) and ZrO2(CTAB) were suitably
Load more

Recommended publications
  • Topic 5: Acids and Bases
    Topic 5: Acids And BAses Topic 5: Acids and Bases C12-5-01 Outline the historical development of acid-base theories. Include: the Arrhenius, Brønsted-Lowry, and Lewis theories C12-5-02 Write balanced acid-base chemical equations. Include: conjugate acid-base pairs and amphoteric behaviour C12-5-03 Describe the relationship between the hydronium and hydroxide ion concentrations in water. Include: the ion product of water, Kw C12-5-04 Perform a laboratory activity to formulate an operational definition of pH . C12-5-05 Describe how an acid-base indicator works in terms of colour shifts and Le Ch âtelier’s principle. C12-5-06 Solve problems involving pH. C12-5-07 Distinguish between strong and weak acids and bases. Include: electrolytes and non-electrolytes C12-5-08 Write the equilibrium expression ( Ka or Kb) from a balanced chemical equation. C12-5-09 Use Ka or Kb to solve problems for pH, percent dissociation, and concentration. C12-5-10 Perform a laboratory activity to determine the concentration of an unknown acid or base, using a standardized acid or base. C12-5-11 Predict whether an aqueous solution of a given ionic compound will be acidic, basic, or neutral, given the formula. suggested Time: 14 hours Grade 12 C hemistry • Topic 5: Acids and Bases SpeCifiC Learning OutCOmeS Topic 5: C12-5-01: Outline the historical development of acid-base theories. Acids and include: the arrhenius, Br ønsted-Lowry, and Lewis theories Bases C12-5-02: Write balanced acid-base chemical equations. include: conjugate acid-base pairs and amphoteric behaviour (2 hours) 1 2 uggesTions for nsTrucTion 0 0 s i - - 5 5 - - Entry-Level Knowledge 2 2 1 1 In Grade 10 Science (S2-2-08), students experimented to classify acids and bases C C : : according to their characteristics.
    [Show full text]
  • Isomerization of Alpha-Pinene Oxide Over Solid Acid
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by ScholarBank@NUS ISOMERIZATION OF ALPHA-PINENE OXIDE OVER SOLID ACID CATALYSTS D. B. R. A. DE SILVA (B.Sc. (Hons.), UNIVERSITY OF PERADENIYA, SRI LANKA) A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF SCIENCE DEPARTMENT OF CHEMISTRY NATIONAL UNIVERSITY OF SINGAPORE 2003 Acknowledgements First and foremost, I would like to thank my supervisor A/P G.K. Chuah, for her constant encouragement, invaluable guidance, patience and understanding throughout the length of my candidature in NUS. I am also grateful to A/P Stephan Jaenicke, for his invaluable guidance. I would also like to thank all the other members of our research group for their kind help and encouragement during my candidature. Thanks are due to my parents and wife for their understanding, encouragement and support. Finally, I wish to express my gratitude to the National University of Singapore for awarding me a valuable research scholarship. i TABLE OF CONTENTS PAGE Acknowledgement i Table of Contents ii Summary v List of Tables vii List of Figures ix Chapter I Introduction 1.1 Mesoporous Molecular Sieves 1 1.1.1 Catalytic Application of Mesoporous Materials 2 1.1.2 Modification of Mesoporous Materials 2 1.1.3 Micro- and Mesoporous Materials 4 1.2 Environment Impact of Solid Catalysts 6 1.3 Solid Acid and Catalysts 8 1.4 Supported Oxide Catalysts 9 1.4.1 Metal Oxide Supported Boron Oxide 13 1.4.2 SiO2-Supported ZrO2 Catalysts 15 1.4.3 InCl3-Supported Solid Acid Catalysts 16 1.5 Methodology
    [Show full text]
  • Notes Acids and Bases
    Notes Acids and Bases Arrhenius Acid Base Theory: In 1884 Svante Arrhenius proposed the first theoretical model for acids and bases. Prior to that time, these chemically opposite substances were described in properties such as their taste; their effects on metals, carbonates, and dyes (called indicators); their feel to the touch, and their ability to react with each other. According to the Arrhenius theory , pure water dissociates to some extent to produce hydrogen ions, H + and hydroxide ions, OH -. When this occurs, equal amounts of H + and OH - ions are produced: + - H2O(l) H (aq) + OH (aq) An acid, according to Arrhenius, is any substance that liberates H + ions when placed in water. When the H + concentration is elevated the OH - concentration decreases, this solution is said to be acidic. Similarly, a base is defined as any substance that liberates OH - ions when placed in water. The resulting solution has a higher concentration of OH - ions than H + ions and is said to be basic, or alkaline. + - ACID: HCl (aq) H (aq) + Cl (aq) + - BASE: NaOH (aq) Na (aq) + OH (aq) Brønsted - Lowry Acid Base Theory: A more general and realistic theory was proposed by two chemists working independent of the other, Johannes Nicolaus Brønsted of Denmark and Thomas Martin Lowry of England. Both chemists are given credit; the theory is named the Brønsted-Lowry theory . Acids are defined as substances that donate H + ions, protons and therefore are called proton donators, while bases are substances that accept protons and are defined as proton acceptors. On this basis, the autoionization of water is given as follows: + - H2O(l) + H 2O(l) H3O (aq) + OH (aq) In this reaction, one water molecule donates a proton, H +, and behaves as an acid, while the other water molecule accepts the proton and behaves as a base.
    [Show full text]
  • Rational Design of Metal Oxide Solid Acids for Sugar Conversion
    catalysts Review Rational Design of Metal Oxide Solid Acids for Sugar Conversion Atsushi Takagaki Department of Applied Chemistry, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan; [email protected]; Tel.: +81-92-802-6711 Received: 15 October 2019; Accepted: 24 October 2019; Published: 29 October 2019 Abstract: Aqueous-phase acid-catalyzed reactions are essential for the conversion of cellulose-based biomass into chemicals. Brønsted acid and Lewis acid play important roles for these reactions, including hydrolysis of saccharides, isomerization and epimerization of aldoses, conversion of d-glucose into 5-hydroxymethylfurfural, cyclodehydration of sugar alcohols and conversion of trioses into lactic acid. A variety of metal oxide solid acids has been developed and applied for the conversion of sugars so far. The catalytic activity is mainly dependent on the structures and types of solid acids. Amorphous metal oxides possess coordinatively unsaturated metal sites that function as Lewis acid sites while some crystal metal oxides have strong Brønsted acid sites. This review introduces several types of metal oxide solid acids, such as layered metal oxides, metal oxide nanosheet aggregates, mesoporous metal oxides, amorphous metal oxides and supported metal oxides for sugar conversions. Keywords: Sugars; cellulose; glucose; 5-hydroxymethylfurfural; lactic acid; solid acid; Brønsted acid; Lewis acid; metal oxide; water-tolerant catalyst 1. Introduction The fundamental features of solid acid catalysts are the reusability of the catalysts, their easy separation from the products and solvents and unnecessary neutralization, which are beneficial to saving energy and cost. Besides these, special requirements of the catalysts for sugar conversion are high recognition ability of sugar molecules and high tolerance against water.
    [Show full text]
  • Acid-Base Catalysis Application of Solid Acid-Base Catalysts
    Modern Methods in Heterogeneous Catalysis Research Acid-Base Catalysis Application of Solid Acid-Base Catalysts Annette Trunschke 18 February 2005 Outline 1. Introduction - basic principles 2. Substrates and products 3. Kinds of acid / base catalysts - examples 4. Characterization of surface acidity / basicity - examples 5. Acid catalyzed reactions 6. Base catalyzed reactions 7. Acid-base bifunctional catalysis 8. Summary and outlook Modern Methods in Heterogeneous Catalysis Research : 18/02/2005 2 1. Introduction - Basic definitions concept acid base - + Brønsted H2O OH + H - - Lewis FeCl3 + Cl [FeCl4] Hydrogen transfer reactions intermediates acid-catalyzed + H+ carbenium ions base-catalyzed + H+ carbanions Modern Methods in Heterogeneous Catalysis Research : 18/02/2005 3 1. Introduction - Basic definitions specific acid / base general acid / base catalysis catalysis + - active H3O or OH undissociated acid or base species groups; a variety of species may be simultaneously active reaction •in solution •gas phase reactions medium / •on the surface of •high reaction temperatures conditions a hydrated solid Advantages of solid acid-base catalysts: • Easier separation from the product • Possible reuse and regeneration • Fewer disposal problems • Non-corrosive and environmentally friendly (but not always!) Modern Methods in Heterogeneous Catalysis Research : 18/02/2005 4 2. Substrates and products solid acid catalysis solid base catalysis substrates •Alkanes, aromatics •Alkenes (components of crude •Alkynes petrolium) •Alkyl aromatics •Alkenes (products of •Carbonyl compounds petrolium cracking (FCC, steam cracking)) products •Gasoline components •Chemical intermediates •Chemical intermediates •Fine chemicals •Fine chemicals Industrial processes in 1999: 103 solid acids worldwide production by catalytic cracking: 500x106 tonnes/y 10 solid bases 14 solid acid-base bifunctional catalysts K.Tanabe, W.F.Hölderich, Applied Catalysis A 181 (1999) 399.
    [Show full text]
  • Efficient Biodiesel Production Via Solid Superacid Catalysis
    RSC Advances REVIEW Efficient biodiesel production via solid superacid catalysis: a critical review on recent breakthrough Cite this: RSC Adv.,2016,6,78351 Peter Adeniyi Alaba,*a Yahaya Muhammad Sanib and Wan Mohd Ashri Wan Daud*a Biodiesel produced from triglycerides and/or free fatty acids (FFAs) by transesterification and esterification has attracted immense attention during the past decades as a biodegradable, renewable and sustainable fuel. Currently, the use of solid superacid catalysts has proved a more efficient and “green” approach due to avoidance of environmental and corrosion problems and reduced product purification procedures. However, it is less viable economically because the reusability is low due to the lack of a hydrophilic/ hydrophobic balance in the reactions that involve the use of inedible feedstock with a high water content. Therefore, this study gives a critical review on recent strategies towards efficient and “green” production of biodiesel via solid superacid catalysis. The strategies discussed include alkyl-bridged Received 1st April 2016 organosilica moieties functionalized hybrid catalysis to improve the hydrothermal stability of superacid Accepted 2nd August 2016 catalysts, pre- and in situ water removal, and process intensification via temperature profile reduction. DOI: 10.1039/c6ra08399d The strategies enabled well-defined porosity and an excellent hydrophobicity/hydrophilicity balance, www.rsc.org/advances which suppressed deactivation by water and glycerol. 1. Introduction posed by fossil diesel. Some studies have revealed that biodiesel has become the most interesting alternative.1–3 The two major There is urgent need for alternative sources of energy due to the precursors of biodiesel are triglycerides and free fatty acids unrenewability, unsustainability and environmental threat (FFAs), which are obtained from edible oil, nonedible oil,4,5 animal fats and used vegetable oils.6 Previously, the most popular biodiesel produced was from edible oil.
    [Show full text]
  • Acid Strength Measurements of Amberlyst 15 Resin, P-Xylene-2
    Reaction Kinetics, Mechanisms and Catalysis https://doi.org/10.1007/s11144-019-01551-7 Acid strength measurements of Amberlyst 15 resin, p‑xylene‑2‑sulfonic acid and chlorosulfonic and sulfuric acid treated SiO2, Al2O3, TiO2 and MgO Marek Marczewski1 · Monika Aleksandrowicz1 · Ewelina Brzezińska1 · Maja Podlewska1 · Mateusz Rychlik1 · Sandra Żmuda1 · Urszula Ulkowska1 · Marek Gliński1 · Osazuwa Osawaru2 Received: 22 November 2018 / Accepted: 11 February 2019 © The Author(s) 2019 Abstract The measurements of the minimum acid strength (H Omin) required for the ini- tiation of cis-stilbene at 303 K and tert-butylbenzene at 313 K, 323 K and 333 K have enabled the establishment of a much more precise acid strength scale based on test reactions. HOmin values obtained were: − 9.0 (cis-stilbene, 303 K), − 9.3, − 9.5 and − 9.9 (tert-butylbenzene, 313 K, 323 K, 333 K). The updated method was used for the determination of the acid strength of diferent catalysts obtained in the reaction of chlorosulfonic and sulfuric acid on diferent oxide carriers. It was found that the acid strength values depended on the basicity of the studied supports. For the supports treated with chlorosulfonic acid the values of acid strength were: − 11.5 < HO ≤ − 10.8 in the case of the less basic SiO 2 and − 9.3 < HO ≤ − 9.0 for the more basic TiO2, Al2O3 and MgO. For the supports treated with sulfuric acid the acid strength was: -9.3 < HO ≤ -9.0 for the less basic SiO2 and TiO2, − 9.0 < HO ≤ − 7.9 for the more basic Al 2O3 and − 7.9 < HO ≤ − 6.9 for the most basic MgO.
    [Show full text]
  • Brønsted and Lewis Solid Acid Catalysts in the Valorization of Citronellal
    catalysts Article Brønsted and Lewis Solid Acid Catalysts in the Valorization of Citronellal Federica Zaccheria 1, Federica Santoro 1, Elvina Dhiaul Iftitah 2 and Nicoletta Ravasio 1,* 1 CNR Institute of Molecular Science and Technology, Via Golgi 19, 20133 Milano, Italy; [email protected] (F.Z.); [email protected] (F.S.) 2 Chemistry Department Faculty of Science, Brawijaya University Jl. Veteran, Malang 65145, Indonesia; [email protected] * Correspondence: [email protected]; Tel.: +39-02-5031-4382 Received: 30 July 2018; Accepted: 12 September 2018; Published: 22 September 2018 Abstract: Terpenes are valuable starting materials for the synthesis of molecules that are of interest to the flavor, fragrance, and pharmaceutical industries. However, most processes involve the use of mineral acids or homogeneous Lewis acid catalysts. Here, we report results obtained in the liquid-phase reaction of citronellal with anilines under heterogeneous catalysis conditions to give tricyclic compounds with interesting pharmacological activity. The terpenic aldehyde could be converted into octahydroacridines with a 92% yield through an intramolecular imino Diels–Alder reaction of the imine initially formed in the presence of an acidic clay such as Montmorillonite KSF. Selectivity to the desired product strongly depended on the acid sites distribution, with Brønsted acids favoring selectivity to octahydroacridine and formation of the cis isomer. Pure Lewis acids such as silica–alumina with a very low amount of alumina gave excellent results with electron-rich anilines like toluidine and p-anisidine. This protocol can be applied starting directly from essential oils such as kaffir lime oil, which has a high citronellal content.
    [Show full text]
  • Optimization of Salix Carbonation Solid Acid Catalysts for One-Step Synthesis by Response Surface Method
    applied sciences Article Optimization of Salix Carbonation Solid Acid Catalysts for One-Step Synthesis by Response Surface Method Ping Lu 1, Kebing Wang 1,* and Juhui Gong 2 1 College of Science, Inner Mongolia Agricultural University, Huhhot 010018, China; [email protected] 2 School of Chemistry and Chemical Engineering, Inner Mongolia University, Huhhot 010018, China; [email protected] * Correspondence: [email protected] Received: 16 March 2019; Accepted: 8 April 2019; Published: 12 April 2019 Featured Application: One of the major problems which we faced in this century was energy shortage, Salix carbon-based solid acid catalyst is a promising method for preparing biodiesel with low-cost catalysts to alleviate the energy crisis. Abstract: Salix carboniferous solid acid catalysts were successfully obtained via one-step carbonization and sulfonation of Salix psammophila in the presence of concentrated sulfuric acid, which was then used in the esterification reaction between oleic acid and methanol to prepare the biodiesel. The esterification rate of the catalyst obtained from the reaction indicated the catalytic performance of the catalyst. Afterwards, the recycling performance of the catalyst was optimized and characterized based on Fourier transform infrared spectrometer. The catalyst performance was examined and optimized through the response surface method, and the catalyst was determined and characterized based on scanning electron microscope (SEM), elemental analysis, thermogravimetric analysis, and infrared analysis. The results suggested that the optimal preparation conditions were as follows: reaction temperature of 125 ◦C, reaction time of 102 min, solid–liquid ratio of 17 g/100 mL, standing time of 30 min, and the highest conversion level of 94.15%.
    [Show full text]
  • A Porous Brønsted Superacid As an Efficient and Durable Solid Catalyst
    Journal of Materials Chemistry A PAPER View Article Online View Journal | View Issue A porous Brønsted superacid as an efficient and durable solid catalyst† Cite this: J. Mater. Chem. A,2018,6, 18712 Qi Sun,‡*a Kewei Hu,‡a Kunyue Leng,b Xianfeng Yi,c Briana Aguila, d Yinyong Sun, c Anmin Zheng, c Xiangju Meng,a Shengqian Mad and Feng-Shou Xiao ‡*a The development of catalysts able to assist industrial chemical transformations is a topic of high importance. In view of the versatile catalytic capabilities of acid catalysts, extensive research efforts are being made to develop porous superacid materials with a high density of accessible active sites to replace molecular acid catalysts. Herein, we report the rational development of a porous Brønsted superacid by combining important elements that target high strength acidity into one material, as demonstrated by grafting the sulfonic acid group onto a highly fluorinated porous framework, where the acid strength and stability are greatly enhanced by an electron-withdrawing environment provided by the polymer backbone, reminiscent of that seen in Nafion® resin. In addition, the densely arranged acid groups that are confined in the three-dimensional nanospace facilitate the transfer of hydrons, thereby further increasing the acidity. By virtue of the pore structure and strong acidity, this system exhibits Received 7th July 2018 excellent performance for a wide range of reactions, far outperforming commercial acid resins under Accepted 12th September 2018 repeated batch and flow reaction conditions. Our findings demonstrate how this synthetic approach may DOI: 10.1039/c8ta06516k instruct the future design of heterogeneous acid catalysts with advantageous reaction capabilities and rsc.li/materials-a stability.
    [Show full text]
  • Studies of Acids, Bases, and Salts by EMF, Conductance, Optical And
    Bureau ol not to ^^' (1 Reference Desk < .brary, taken iry. OCT 4 1965 NBS technical ^2©te 271 ELECTROCHEMICAL ANALYSIS: STUDIES OF ACIDS, BASES, AND SALTS BY EMF, CONDUCTANCE, OPTICAL AND KINETIC METHODS JULY 1964 TO JUNE 1965 Edited by Roger G. Bates I. S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS , NATIONAL BUREAU OF STANDARDS Technical Note 271 ISSUED SEPTEMBER 6, 1965 ELECTROCHEMICAL ANALYSIS: STUDIES OF ACIDS, BASES, AND SALTS BY EMF, CONDUCTANCE OPTICAL AND KINETIC METHODS JULY 1964 TO JUNE 1965 Edited by Roger G. Bates Electrochemical Analysis Section Analytical Chemistry Division Institute for Materials Research NBS Technical Notes are designed to supplement the Bu- reau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be listed or referred to in the open literature. For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C., 20402 - Price 60 cents FOREWORD The Analytical Chemistry Division was established as a .separate division at the National Bureau of Standards on September 1, 1963, and became part of the Institute for Materials Research in the February 1, 1964, reorganization. It consists at present of seven sections and about 85 tech- nical personnel encompassing some 50 different analytical competences from activation analysis and atomic absorption to vacuum fusion and x-ray spectroscopy. These competences, and in turn the sections which they comprise, are charged with research at the forefront of analysis as well as aware- ness of the practical sample, be it standard reference material or service analysis.
    [Show full text]
  • Catalytic Applications of Solid Acid/Base Catalyst for the Benign Synthesis of Fine Chemicals
    CATALYTIC APPLICATIONS OF SOLID ACID/BASE CATALYST FOR THE BENIGN SYNTHESIS OF FINE CHEMICALS A THESIS SUBMITTED TO THE UNIVERSITY OF PUNE FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN CHEMISTRY BY LALITA B. KUNDE UNDER THE GUIDANCE OF Dr. S. P. GUPTE AT CHEMICAL ENGINEERING AND PROCESS DEVELOPMENT DIVISION NATIONAL CHEMICAL LABORATORY PUNE-411 008, INDIA SEPTEMBER 2011 CERTIFICATE This is to certify that, the work incorporated in the thesis entitled “CATALYTIC APPLICATIONS OF SOLID ACID/BASE CATALYST FOR THE BENIGN SYNTHESIS OF FINE CHEMICALS” submitted by Ms. Lalita B. Kunde, for the degree of Doctor of Philosophy, was carried out by the candidate under my supervision, in the Chemical Engineering and Process Development Division, National Chemical Laboratory, Pune-411008, India. Such material as has been obtained from other sources has been duly acknowledged in the thesis. Dr. S.P.Gupte September 2011 (Research Guide) Pune Declaration by the candidate I hereby declare that the thesis entitled “Catalytic Applications of Solid Acid/Base Catalyst for the Benign Synthesis of Fine Chemicals’’ submitted by me for the degree of Doctor of Philosophy, to the University of Pune, is the record of work carried out by me under the guidance of Dr. S. P. Gupte and has not formed the basis for the award of any degree, diploma, associateship, fellowship, titles in this or any other University or other institution of higher learning. I further declare that the material obtained from other sources has been duly acknowledged in this thesis. Lalita B. Kunde September 2011 (Candidate) Pune Dedicated to My Parents Acknowledgement There are many people who have actively helped me during the tenure of my Ph.D.
    [Show full text]