Crystal engineering has advanced the strategies of design and synthesis of organic solids with the main focus being on improving the properties of the developed materials. Research in this area has a significant impact on large-scale manufacturing as industrial processes may give rise, at various stages, to stress-induced transformations and product modification. This thesis investigates the solid-state properties at play in the case of the surface and structural reorganization which results from the stress within a crystal during the drying of labile multicomponent organic solids. Chapter 1 introduces various concepts in solid-state chemistry and explores their application in the manufacture of solid pharmaceuticals. The significance of stress-induced transformations during the drying process is illustrated by reactions associated with crystal decomposition processes such as dehydration, desolvation and sublimation. The chapter also introduces carbamazepine (CBZ) multicomponent materials as models for the studies of stress-induced transformations. Chapter 2 presents the experimental section of the work and describes the materials, methods and equipment used for the study. Chapter 3 presents the analysis of the various crystal structures of CBZ. The crystal forms are classified with an emphasis on a comparison of intermolecular interactions, coformer arrangement, crystal packing and the geometric parameters of slip/cleavage planes within the crystals. Chapter 4 details the experimental methods for preparation of the samples. Cooling solution crystallization was the standard method which has been selected, and crystal habit and surface variations have been studied as a function of the solution concentration and the crystallization environment. Attention is given, in particular, to the preparation of carbamazepine dihydrate and the specific cocrystals carbamazepine cocrystals formed with benzoquinone and oxalic acid. Chapter 5 is devoted to the dehydration of carbamazepine dihydrate for samples prepared and examined in approximate 1-gram laboratory scale quantities. It explores the effect of vacuum, temperature, humidity and seeding on the surface and bulk properties of the products. Chapter 6 presents the solid-state characterization results obtained for samples crystallized at a much larger scale (ca. kilogram quantities) with a particular emphasis placed on their mechanical properties. It explores the comparison of large scaled batches with laboratory scale samples in order to obtain a greater understanding of how small-scale laboratory studies may be extrapolated to more commercial processes. Chapter 7 present results on the stress-induced transformations of carbamazepine solvates and cocrystals. It details the effect of thermal decomposition on the surface and bulk properties of the products, possible seeding effects, and the interconversion between carbamazepine dihydrate and carbamazepine benzoquinone cocrystal. Chapter 8 combines the research findings concerning the structural analyses of the materials in the context of current literature. Limitations related to the use of carbamazepine as a model and to the experimental set-up are also explored. In the final chapter conclusions are presented which correlate observations made on the crystallization and decomposition of multicomponent materials operating at small-scale to effects appropriate to manufacturing of pharmaceuticals at large scale.

Two different research projects are described in this dissertation. The first one focuses on microwave-promoted iminyl radical cyclization for the formation of azaheterocycles which are embedded within numerous pharmaceuticals and biologically active natural products (such as clindamycin, eletriptan, moxiflaxin, etc.). We are quite interested in this project because of the significance of nitrogen-containing heterocycles as pharmaceuticals and organocatalysts combined with the need for safe, simple, and economical means of constructing them. We have successfully developed an efficient one-step synthesis of 2-acylpyrroles and diastereoselective dihydropyrroles from readily available oxime ether substrates. This remarkably efficient and environmentally friendly methodology should be useful for rapid and easy preparation of potent drugs containing pyrrolidine ring systems. The second project focuses on the total synthesis of yaku'amide A. The natural compound, isolated from a marine sponge in 2010, is a medium-sized peptide that contains bulky dehydroamino acids. It has an excellent IC50 value (14 ng/mL) against leukemia cells, making it a promising anticancer agent. Because of the unique anticancer profile, potent bioactivity, and limited supply, the natural product was attractive to us for an efficient synthesis and mechanistic investigation. We have devised more efficient strategies compared to Inoue's methods for the synthesis of bulky ∆AAs and their incorporation into peptides, which are innovative and will allow us to synthesize yaku'amide A rapidly and conveniently. A one-pot sequence consisting Martin sulfurane mediated anti dehydration, azide reduction, and O→N acyl transfer was developed for the construction of E- and Z-dehydroisoleucine-containing peptides. We also developed a three-step synthesis of N-terminal acyl group involving a one-pot indium-catalyzed cross-Claisen condensation/reduction from a known compound. The most hindered coupling reaction of pentapeptide acid and nanapeptide amine in the late stage is accomplished. Our total synthesis of yaku'amide A can be completed in 19 longest linear steps and 66 total steps. Further identification of yaku'amide A for elucidation of its biological target and mode of action will be explored, which will open up new avenues in the fight against cancer.

Drying with the help of sun and wind is one of the oldest methods of food preservation known to man, but artificial drying, or dehydration, has been developed and used extensively only during the last two decades. The problem in dehydration is that the water content must be decreased sufficiently to maintain the stability of the product by retarding the rates of deteriorative biochemical, microbiological, and enzymatic reactions during subsequent storage. At the same time irreversible changes should not be brought about.

La congélation des produits alimentaires est un procédé qui permet d'augmenter leur durée de conservation. Ceci est possible grâce à l'abaissement de la température mais surtout à la solidification de l'eau réduisant la disponibilité de l'eau nécessaire au développement des micro-organismes. Cependant, si les produits ne sont pas emballés ou si l'emballage n'est pas adhérent à leur surface pendant la congélation, un transfert d'eau a également lieu simultanément à la libération de chaleur. Ce transfert d'eau se traduit par la déshydratation des produits qui implique une perte de masse. Celle-ci a un impact direct sur la masse de produit congelé qui pourra être vendue et donc un coût économique pour les industriels.La cristallisation de l'eau est également un paramètre clé de la congélation. En effet, les caractéristiques des cristaux de glace formés pendant la congélation (nombre, taille et forme) peuvent provoquer des modifications de structure des aliments et des dommages irréversibles. Ceux-ci se traduisent par la modification des propriétés organoleptiques et nutritionnelles des produits une fois décongelés et une baisse de leur qualité.Que ce soit pour la déshydratation ou la cristallisation, les conditions opératoires de congélation (température, vitesse d'écoulement d'air et hygrométrie) ainsi que certaines caractéristiques des produits (température initiale, surface, épaisseur) ont une influence importante. L’objectif de la thèse est d’étudier et savoir estimer la perte en eau et les caractéristiques des cristaux formés dans un aliment non poreux en fonction des conditions opératoires afin de choisir une technologie de congélation adaptée.Le travail a été axé sur l'étude des transferts de chaleur et de matière (eau) à la surface et à l'intérieur du produit lors de la congélation à deux niveaux d'échelle : macroscopique pour la déshydratation et microscopique pour la cristallisation. Cette approche multi-échelles s’est appuyée à la fois sur l’expérimentation et sur la modélisation.Pour ce qui est de la déshydratation, un dispositif expérimental a été conçu à l’échelle du produit pour mesurer la variation de la masse et de la température de l’aliment au cours de sa congélation (conditions mécaniques ou cryogéniques).Parallèlement, un modèle (1D) de prédiction de la déshydratation et de la durée de congélation en fonction du produit (homogène et non poreux) et des conditions opératoires de congélation a été développé. Cette étude a été réalisée pour un produit modèle, le gel de méthyl-cellulose (Tylose®) et pour de la viande hachée de bœuf (5 % de matière grasse).Pour l’étude de la cristallisation, un modèle à l’échelle des cristaux (2D) a pour vocation de représenter les phénomènes liés au changement de phase de l’eau (apparition et croissance des cristaux) en fonction des conditions opératoires de congélation. Il simule la cristallisation de l’eau dans des solutions notamment en prenant en compte la diffusion des molécules de solutés dans la solution cryo-concentrée ainsi que la libération et la dissipation de la chaleur latente de solidification de l'eau.Des observations de la cristallisation au sein d'échantillons de viande hachée de bœuf ont été faites par micro-tomographie à rayon X et cryo-microscopie électronique à balayage sur des échantillons congelés mais aussi par microscopie électronique à balayage et microscopie optique sur des échantillons lyophilisés (après congélation en conditions mécaniques ou cryogéniques). / Freezing extends food shelf life by lowering the temperature and mainly thanks to water solidification which decreases water availability for micro-organism growth. Nevertheless, if the food is not packaged or if the packaging is not adherent to its surface, a water transfer occurs simultaneously with the heat transfer during freezing. This water transfer leads to product dehydration which means weight loss. Food dehydration during freezing has consequences on the product weight and so has an economic cost for industrials.Water crystallization is also an important parameter of the freezing process. Indeed, ice crystal characteristics (number, size and shape) may induce food structure changes and irreversible damages. These modifications can alter organoleptic properties and food quality after thawing.Freezing operating conditions (temperature, flow velocity, hygrometry) and some food characteristics (initial temperature, surface, thickness) have an influence on both dehydration and water crystallization.The objective of this thesis is to study and to be able to estimate the water loss and crystal characteristics for non-porous food according to the freezing operating conditions in order to select the best freezing technology.The work was focused on the multi-scale study of heat and mass (water) transfers during freezing, at the product surface and throughout the product : on a macroscopic point of view for dehydration and on a microscopic point of view for crystallization. Each study is built on an experimental and a modelling work.For dehydration, an experimental device was developed to measure weight loss and product temperature kinetics during freezing (mechanical and cryogenic freezing conditions).Moreover, a predictive model (1D) was established for estimation of dehydration and freezing time according to the product and the freezing conditions. Dehydration was studied with a model material (methylcellulose gel-Tylose®) and with minced beef (5 % fat).For crystallization, a model at crystal scale (2D) aims to simulate phenomena related to the water phase change (nucleation and crystal growth) according to the freezing operating conditions. It takes into account water crystallization in solution considering the diffusion of the solute in the cryo-concentrated solution, the release and dissipation of the latent heat of water solidification.Crystallization observations were done in frozen samples of minced beef by X-ray micro-tomography and by cryo-scanning electron microscopy. Some visualizations were also carried out on freeze-dried samples by scanning electron microscopy and optical microscopy (after mechanical or cryogenic freezing).

<p>Kukuruzni plamenac,&nbsp;<em> Ostrinia nubilalis</em>Hb, je insekt umerenog klimatskog područja koji niske&nbsp; zimske temperature preživljava ulaskom u dijapauzu u stadijumu gusenice. Tokom dijapauze gusenice postaju otporne na hladnoću i sposobne&nbsp; da prežive vanćelijsko zamrzavanje telesne tečnosti.<br />Cilj ove teze je bio razumevanje mehanizama otpornosti na niske temperature gusenica&nbsp; <em>O. nubilalis </em>na ćelijskom i molekularnom nivou.<br />Istraživanja su rađena na letnjim, nedijapauzirajućim gusenicama kao i zimskim gusenicama koje su&nbsp; bile izlagane uticaju niskih temperatura u različitim periodima dijapauze. Određivan je režim telesne vode, sadržaj poliola i &scaron;ećera kao mogućih krioprotektora, kao i NMR metabolomički profili. Zbog pretpostavljene uloge atioksidativnog sistema za&scaron;tite (ADS) u procesima vezanim za otpornost na<br />hladnoću određivane su aktivnosti određenih antioksidativnih enzima kao i produkcija H₂O₂i melanina.<br />Rezultati ukazuju da je izlaganje niskim temperaturama kod dijapauzirajućih gusenica praćeno preraspodelom osmotski aktivne (OA) vode na nivou hemolimfe i masnog tela, pri čemu nivo OA&nbsp; opada u hemolimfi, a raste u masnom telu. Nivo osmotski neaktivne vode (OI) ostaje nepromenjen. Nivo glicerola je značajno veći kod dijapazirajućih u odnosu na nedijapauzirajuće gusenice, a njegov nivo se vi&scaron;estruko povećava pri izlaganju niskim temperaturama na sredini dijapauze ukazujući na njegov značaj kao glavnog krioprotektora u ovoj fazi dijapauze. Krajem dijapauze sa<br />niskim temperaturama vi&scaron;estruko se povećava nivo trehaloze, glukoze i fruktoze, a tek neznatnoglicerola.<br />NMR metabolomički profili su potvrdili značaj glicerola u otpornosti na hladnoću, ali i<br />aminokiselina alanina i prolina. U nedijapuzirajućim i dijapauzirajućim gusenicama na 5^oC registrovano je prisustvo putrescina, poznatog markera stresa, a&nbsp; njegova uloga, kao i moguća uloga njegovih daljih metabolita spermina i spermidina tek treba da se ispita. Odgovor ADS-a na niske temperature takođe je zavistan od perioda dijapauze. Na sredini dijapauze, na temperaturi od&nbsp; -3^oC, a ne i na&nbsp; -16^oC, dolazi do povećanja koncentracije H₂O_2&nbsp;i signala melanin radikala, dok aktivnost katalaze i CuZnSOD, ali ne i MnSOD, opada. Kako je glavni izvor H₂O₂mitohondrijalna MnSOD, ovaj enzim je verovatno uključen u regulaciju unutarćelijskog nivoa H₂O₂.<br />Produkcija melanina verovatno je u funkciji odbrane organizma od oksidativnog stresa zbog uklanjanja intracelularnog H₂O_2. Predpostavljamo da je temperatura od&nbsp; -3^oC ključna temperatura za pokretanje adaptivnih&nbsp; mehanizama za otpornost na hladnoću gusenica<em> O.nubilalis</em>. Promene u ADS sa izlaganjem niskim temperaturama nisu primećene na kraju dijapauze.<br />Rezultati ove teze ukazuju da je dijapauza dinamično stanje podeljeno na faze, a sama otpornost na hladnoću dobroregulisana i usklađena sa ukupnim metaboličkim potrebama tokom dijapauze.</p> / <p>&nbsp;European corn borer, <em>Ostrinia nubilalisHb</em>, is insect species of the temperate zone that survives low winter temperatures as a diapausing larva. Diapausing larvae are cold hardy and tolerate the formation of extracellular ice crystals.</p><p>The aim of this thesis was to investigate the cellular and molecular basis of&nbsp; <em>O. nubilalis </em>cold&nbsp;hardiness.</p><p>Thus, our research was focused on the non-diapausing (ND) as well as the diapausing (D) larvae that&nbsp;were exposed to low temperatures during different &nbsp;diapausal phases. Body water management,&nbsp;content of polyols and sugars as well as &nbsp;metabolomic NMR profiles, were assessed. Because of the&nbsp;possible role of the antioxidant defence system (ADS) in insects&rsquo; cold hardiness, antioxidant&nbsp;enzymes activity as well as the content of H₂O_2&nbsp;and melanin was measured.</p><p>Results showed that the exposure of diapausing larvae to low temperatures provokes exchanges of&nbsp;osmotically active (OA) body water between hemolymph and fat body. With low temperatures, OA&nbsp;water was decreased in hemolymph, increased in fat body while the content of osmotically inactive&nbsp;(OI) water was constant.</p><p>The level of glycerol was higher in diapausing compared to non-diapausing larvae, and showed 2-fold increase with the exposure to low temperatures in mid-diapause. This confirmed that glycerol is&nbsp;O.nubilalismajor cryoprotectant in mid-diapause cold hardiness. On the other hand, at the end of&nbsp;the diapause, the content of trehalose, glucose and fructose, except the glycerol, was substantially&nbsp;increased.</p><p><br />NMR metabolic profiling confirmed the importance of glycerol in diapausal cold hardiness as well&nbsp;as implied the importance of alanine and proline. In addition to this, putrescine, a well-know stress&nbsp;marker, were detected in ND and D larvae at 5^oC suggesting that its metabolites, namely sperimine&nbsp;and spermidine, can have potential role in diapause.</p><p>The ADS response to low temperatures differs during diapause timescale. In mid-diapause,&nbsp;exposure of larvae to&nbsp; -3^oC,&nbsp; but not&nbsp; -16^oC, resulted in the elevation of H₂O_2&nbsp;concentration and&nbsp;melanin radical signal. On the other hand, the activity of catalase and CuZnSOD, but not of&nbsp;MnSOD, was decreased. Since the mitochondrial MnSOD is the main source of H₂O2, this enzyme&nbsp;probably regulates the intracellular level hydrogen peroxide. Melanin probably serves as a defence&nbsp;mechanism against oxidative stress while it reduces the level of intracellular H₂O₂. Temperature of -3^oC is probably the &lsquo;trigger temperature&rsquo; for mechanism in adaptation of larvae&nbsp; <em>O.nubilalisto </em>&nbsp;cold.&nbsp;There were no changes detected in ADS during exposure to cold in the end of diapausing period.</p><p>The results of this thesis suggested that the <em>O. nubilalis</em> diapause is rather dynamic state divided into&nbsp;different phases and that the cold hardiness is highly regulated and in accordance with the current&nbsp;metabolic demands of each diapausal phase.</p>

The petroleum industry is currently moving to meet the ever-rising demand for oil and gas production. As onshore fields become depleted and decline in production, exploration and production companies have started venturing further offshore. To support this activity, there is need for new subsea production technologies to develop deepwater and ultra deepwater fields.Woodside Hydrocarbon Research Facility (WHRF) at Curtin University of Technology is working on natural gas dehydration processing using gas hydrate technology. Through the studies, a novel gas dehydration process has been developed and now proposed for subsea application. Natural gas dehydration processes generate both a treated dry gas stream and a waste stream of condensate consisting of both hydrocarbons and water. This condensate can be reinjected to the reservoir formation but this is not always economic or practical. Availability of an alternative means of treatment and disposal of the condensate would be advantageous. This study aims to investigate and to provide a basis for the design of such an alternative scheme by constructing a floating separator for the treatment and disposal of waste condensate from subsea dehydration stage.A model was developed to simulate the process of evaporation of condensate from the proposed floating separator. The calculations were performed taken into account zero wind speed and an ambient temperature around 34 C. The simulation results showed that condensate skimming time was found to be 15 days for flowrate (Qin) of 100 bbd associated with specific separator diameter and total height dimensions. By considering the ratio of diameter to total height of 2.5, the floating separator was designed to enhance the evaporation rate and to get overall structure stability due to the mechanical restrictions that might be encountered in the sea.

Acrolein is an indispensable chemical intermediate with a rising demand in recent years. The concern of the increase of propylene prices due to the shrinking supply of nonrenewable crude oil makes the acid-catalyzed gas-phase glycerol dehydration to acrolein a prime candidate for research. Our analysis showed that the sustainable acrolein production from glycerol was both technically and economically viable. Alumina2700® (Al) and Silica1252® (Si) loaded with silicotungstic acid (HSiW) possessed distinct features while provided equally good acrolein yield (73.86mol% and 74.05mol%, respectively) optimally. Due to the unique non-equilibrium characteristics, non-thermal plasma (NTP) could promote a variety of chemical reactions; however, its application in a dehydration process remained blank. This study used the reaction of glycerol dehydration to acrolein to probe whether NTP could 1) improve acrolein yield during dehydration, 2) suppress the coke formation and regenerate the catalyst, and 3) modify the properties of the catalyst. The dielectric barrier discharge configuration was used to generate NTP; various NTP field strengths and also their interaction with temperature and the catalyst were investigated. The results showed that NTP improved the glycerol conversion and that NTP with a proper field strength increased acrolein selectivity. The optimal acrolein yields of 83.6 mol% and 83.1 mol% were achieved with 3.78 kV/cm NTP and 4.58 kV/cm NTP at 275°C for HSiW-Al and HSiW-Si, respectively. The application of NTP-O2 (5% oxygen in argon, 4.58 kV/cm) during glycerol dehydration significantly suppressed coke formation on HSiW-Si. NTP-O2 could regenerate the deactivated HSiW-Si at low temperatures by removing both soft and hard coke at various rates. NTP-O2 with higher field strength, at medium operation temperature (150ºC) and in argon atmosphere was more effective for coke removal/catalyst regeneration. Applying NTP to the catalyst fabrication showed some capabilities in modifying catalyst properties, including enlarging surface area, preserving mesopores, increasing acid strength and Brønsted acidity. NTP with argon as the discharge gas performed better in these modifications than NTP with air as the discharge gas.

The study on dehydration of frozen saskatoon berries and the need for dried fruits has been strategically identified in the prairies. Our motivation was to find a suitable method for dehydration in order to extend saskatoon berry shelf life for preservation. Microwave, convection and microwave-convection combination drying processes were identified to finish-dry saskatoon berries after osmotic dehydration using sucrose and high fructose corn syrup (HFCS) sugar solutions. Osmotic dehydration removes moisture in small quantities and also introduces solutes into the fruit that acts as a preservative and also reduces the total drying time. <p>Due to the very short harvesting season of saskatoon berries, an accelerated process like microwave combination drying can bring down the moisture to safe storage level, immediately after harvest. Untreated and osmotically dehydrated berries were subjected to convection (control), microwave and microwave-convection combination drying conditions at different product drying temperatures (60, 70 and 80C) until final moisture content was 25% dry basis. A laboratory-scale microwave combination dryer was developed, built with temperature and moisture loss data acquisition systems using LabView 6i software. Thin-layer cross flow dryer was used for convection-only drying and for comparison. <p>Drying kinetics of the drying processes were studied and curve fitting with five empirical equations including Page equation, was carried to determine drying constant, R2 and standard error values. The microwave-combination drying method proved to be the best for drying saskatoon berries. Dehydrated product quality analysis by means of color changes, rehydration ratio measurements and observed structural changes with scanning electron microscope technique were the factors in drying method selection for saskatoon berries.<p> This research was instrumental in the modification and development of a novel drying system for high-moisture agricultural materials. Microwave-convection combination drying at 70oC, yields good results with higher drying rates and better end-product quality.

The study on dehydration of frozen saskatoon berries and the need for dried fruits has been strategically identified in the prairies. Our motivation was to find a suitable method for dehydration in order to extend saskatoon berry shelf life for preservation. Microwave, convection and microwave-convection combination drying processes were identified to finish-dry saskatoon berries after osmotic dehydration using sucrose and high fructose corn syrup (HFCS) sugar solutions. Osmotic dehydration removes moisture in small quantities and also introduces solutes into the fruit that acts as a preservative and also reduces the total drying time. <p>Due to the very short harvesting season of saskatoon berries, an accelerated process like microwave combination drying can bring down the moisture to safe storage level, immediately after harvest. Untreated and osmotically dehydrated berries were subjected to convection (control), microwave and microwave-convection combination drying conditions at different product drying temperatures (60, 70 and 80C) until final moisture content was 25% dry basis. A laboratory-scale microwave combination dryer was developed, built with temperature and moisture loss data acquisition systems using LabView 6i software. Thin-layer cross flow dryer was used for convection-only drying and for comparison. <p>Drying kinetics of the drying processes were studied and curve fitting with five empirical equations including Page equation, was carried to determine drying constant, R2 and standard error values. The microwave-combination drying method proved to be the best for drying saskatoon berries. Dehydrated product quality analysis by means of color changes, rehydration ratio measurements and observed structural changes with scanning electron microscope technique were the factors in drying method selection for saskatoon berries.<p> This research was instrumental in the modification and development of a novel drying system for high-moisture agricultural materials. Microwave-convection combination drying at 70oC, yields good results with higher drying rates and better end-product quality.

Due to overconsumption, fossil reserves are rapidly being depleted and various sources predict that they will not last until the end of 21st century. Moreover, the increase in the rate of global warming and the polluting matter emitted by the vehicles consuming fossil fuels has increased the search for renewable and clean energy sources. Alcohols and ethers, which contain fewer pollutants and have better burning properties, are commonly thought among clean fuel alternatives. Among the potential clean energy sources, dimethyl-ether is already in use in the automotive industries of many countries such as China and Japan, due to its low NOx and CO2 emissions, high cetane rating and efficient combustion characteristics, especially in diesel engines. In this work, dimethyl-ether synthesis is achieved using methanol dehydration reaction over solid acid catalysts. For this purpose, three different mesoporous MCM-41 type aluminum silicates have been synthesized with direct hydrothermal synthesis method and aluminum is added to the synthesized SBA-15 catalyst using impregnation method. Apart from the catalysts synthesized, different commercial catalysts such as aluminum oxide in different forms (&amp / #945 / and &amp / #947 / ), Nafion NR-50 and Nafion SAC-13 have also been tested in this reaction. These materials were characterized by methods such as XRD, EDS, SEM, and N2 physical adsorption and DRIFTS were also investigated in terms of paramters such as the conversion of methanol to products, selectivity and yield. The analyses have shown that AlSi1 is the most active of all the aluminum silicates synthesized in both 0.136 and 0.27 s.g/cm3 space times, with up to 80% methanol conversion in all temperatures tested. AlSi1 also has low by-product formation and similar to other aluminum silicates, its dimethyl-ether selectivity approaches 1 at 4000C. Among all synthesized catalysts, the dimethyl-ether yield was seen to be the highest for Al-SBA-15, which approaches 0.5 at 4000C for both space times. For all aluminum silicates synthesized, about 40% dimethyl-ether yield was obtained at the same temperature and space times. Among the aluminum oxides, &amp / #945 / -alumina was seen to be superior to others in &amp / #947 / forms in terms of conversion selectivity and yield, especially at low temperatures. As to Nafion catalysts, due to its much higher surface area and high Bronsted acidity, Nafion SAC-13 has shown higher activity compared to Nafion NR-50 for all temperatures and space times tested.