Acid Ion Exchange Research Articles

Glycerol etherification over acid ion exchange resins: effect of catalyst concentration and reusability

AbstractBackgroundA study of the effect of different ion exchange resins, Amberlyst 15, Amberlite 200 and Amberlite IRC‐50, on glycerol etherification with tert‐butyl alcohol was performed. The best catalyst was selected based on the activity and selectivity values. The capability of reusing this catalyst after different pre‐treatments was analysed. A kinetic model was developed including the effect of catalyst concentration and temperature.ResultsAmberlyst 15 led to the highest glycerol conversion, the highest product yield, and it could be reused following proper pre‐treatment with methanol. The effect of catalyst concentration was evaluated and included in a previous kinetic model. Simulated results were found to be suitably fitted to the experimental ones.ConclusionsThe high activity value of Amberlyst 15 is related to its high acidity and better textural properties. Reuse of this catalyst was possible with an appropriate previous treatment. A kinetic model was validated including the effect of catalyst concentration and temperature on reactants conversion and products distribution. © 2013 Society of Chemical Industry

설폰화 활성탄 촉매를 이용한 솔비톨의 아이소소바이드로의 탈수반응

불균일계 고체산 촉매인 설폰기(Sulfonyl Group) 함유 활성탄 촉매를 이용하여 솔비톨(Sorbitol)의 아이소소바이드로(Isosorbide)의 탈수반응을 수행하였다. 설폰화 반응(Sulfonation)에 의해 제조된 설폰화 활성탄 물질에 대해 대표적인 상업용 산촉매인 설폰화 지르코니아(Sulfated <TEX>$ZrO_2$</TEX>)와 산성 이온교환수지 Amberlyst-36과 솔비톨 탈수반응의 촉매활성을 비교하였다. 설폰화 활성탄 촉매를 이용하여 423.15 K에서 솔비톨의 탈수 반응 결과, 100% 솔비톨 전환율과 52% 아이소소바이드 선택도를 얻었다. 설폰화 활성탄은 낮은 설폰기 농도(0.5 mmol/g)에도 불구하고 높은 표면적으로 인해 423.15 K에서 Amberlyst-36과 유사한 솔비톨 탈수 반응 특성을 보이며, Amberlyst-36 대비 473.15 K 이상 고온에서도 안정한 특성을 보이는 고체산 촉매로 판단되었다. 또한, 솔비톨 탈수반응 결과를 바탕으로 반응과 생성물의 분리를 동시에 할 수 있는 반응증류 공정에 설폰화 활성탄 촉매를 적용한 결과, 기존 황산 공정 대비 2배 이상 빠른 반응시간에 단위 설폰산 농도 기준으로 4배 이상 높은 아이소소바이드 수율을 얻을 수 있었다. A sulfonated activated carbon (AC-<TEX>$SO_3H$</TEX>) was used as a solid acid catalyst for dehydration of sorbitol to isosorbide and its catalytic performance was compared with the commercial solid acid such as acidic ion exchange resin, Amberlyst-36, and sulfated copper oxide. The catalytic performance with 100% sorbitol conversion and 52% isosorbide selectivity was obtained over AC-<TEX>$SO_3H$</TEX> at 423.15 K. Although AC-<TEX>$SO_3H$</TEX> possessed only 0.5 mmol/g of sulfur content, it showed the similar dehydration activity of sorbitol to isosorbide with Amberlyst-36 (5.4 mmol/g) at 423.15 K. Based on the high thermal and chemical stability of AC-<TEX>$SO_3H$</TEX>, one-step reactive distillation, where isosorbide separation can be carried out simultaneously with sorbitol dehydration, was tried to increase the recovery yield of isosobide from sorbitol. The reactive distillation process using AC-<TEX>$SO_3H$</TEX>, the turnover number of AC-<TEX>$SO_3H$</TEX> was 4 times higher than the conventional two-step process using sulfuric acid.

Preliminary crystallographic analysis of the kinase domain of SAD-1, a protein essential for presynaptic differentiation in Caenorhabditis elegans.

SAD-1 is a serine/threonine kinase which plays an important role in the regulation of both neuronal polarity and synapse formation in Caenorhabditis elegans. The kinase domain of SAD-1 from C. elegans was overexpressed in Escherichia coli BL21 (DE3) cells and purified to homogeneity using nickel-nitrilotriacetic acid metal-affinity, ion-exchange and gel-filtration chromatography. Diffraction-quality crystals were grown using the sitting-drop vapour-diffusion technique from a condition consisting of 1 M CAPSO pH 9.6, 10%(w/v) polyethylene glycol 3350. The crystals belonged to the monoclinic space group C2, with unit-cell parameters a = 205.4, b = 57.1, c = 71.7 Å, β = 106.1°. X-ray diffraction data were recorded to 3.0 Å resolution from a single crystal using synchrotron radiation.

Synthesis and characterization of PVDF supported silica immobilized phosphotungstic acid (Si-PWA/PVDF) ion exchange membrane

An ion exchange membrane was synthesized by impregnating sub-micron sized silica-immobilized phosphotungstic acid (Si-PWA) particles on a porous (poly vinylidene fluoride) (PVDF) film. Surface morphology, crystalline nature and thermal stability of the membrane were studied. The membrane was found to have a defect free surface, which contained both crystalline and amorphous phases and was stable up to 350°C. Electrochemical properties (transport number) of membranes of two different PWA/TEOS (tetraethoxyorthosilicate) ratios were compared and the one with a higher ratio gave better properties. Ion exchange capacity (IEC) of 0.82meq/g and counter-ion transport number of 0.91 indicated good electrochemical properties of the membrane synthesized with sol of PWA/TEOS ratio of 1.5.

Hydration of ion exchangers: Thermodynamics and quantum chemistry calculations

Comparative studies of the state of water molecules in carboxylic acid resins were carried out using classic thermodynamics and ab initio quantum chemical calculation of the structure of representative fragments of their polymeric matrix in the presence of different amounts of water molecules. Water sorption isotherms were obtained for H+, Li+, Na+, K+ Mg2+, Ca2+ and Ba2+ forms of the carboxylic acid ion exchanger Lewatit S8227 using the isopiestic method. Quantum chemistry calculations were performed by the Firefly QC package, which is partially based on the GAMESS (US) source code, on the theory level RHF/MINI. Atomic structures of fragments of the resin interior containing 1–6 monomeric residues and 0–10 water molecules per functional group were computed. It has been shown that the water sorption isotherms are well described by the previously derived equation on the assumption of the presence in the swollen ion exchanger of one or two formal hydrates. Quantum chemistry calculations allow independent evaluation of the number of water molecules in the hydrates and in so doing reduce the number of fitting parameters needed for quantitative description of the water sorption isotherms. They also allow classifying the water molecules in the resin according to the type of interaction with fixed ion–counter-ion ion pair.

Recovery of vanadium, potassium and iron from a spent vanadium catalyst by oxalic acid solution leaching, precipitation and ion exchange processes

A spent vanadium catalyst was leached in an oxalic acid solution to recover vanadium, potassium and iron. The effects of time, temperature, acid concentration, phase ratio and catalyst particle size were studied. The results showed that for a 180–250μm catalyst leached for 4h at 323K in the presence of 2% oxalic acid solution at a liquid:solid ratio of 25:1, the extent of leaching of V, K and Fe was about 91%, 92% and 63%, respectively. Studies on the separation of vanadium from iron were conducted. The effect of pH on the concentration of the investigated compounds in post-leaching solution was presented. Additionally, separation of vanadium from such a solution was investigated by the ion exchange method. Three types of polymer strongly acidic ion exchangers were used. The ion exchange tests indicate that only potassium and iron were loaded from the post-leaching solution. On this basis a flowsheet for the proposed process of a complex utilization of spent vanadium catalyst is presented.

Removal of Cationic Dyes by Polyphenylene Sulfide-Based Strong Acid Ion Exchange Fiber

PPS-based strong acid ion exchange fiber was used to absorb cationic dye basic fuchsin and methyl blue in solution. The experimental results showed that the amount of methylene blue and basic fuchsin absorbed increased respectively with increasing of initial concentration from 100 to 600 mg/L. The adsorption capacity of the fiber was up to 604.81mg/g of basic fuchsin and to 618.94mg/g of methylene blue. The removal rate of the methylene blue reached 99.9% from 100 to 500mg/L, but of basic fuchsin from 100 to 300mg/L. Adsorption kinetic equation for basic fuchsin can be expressed as a pseudo-second-order dynamic process. The fiber is to be perfect prospect for the wastewater treatment because of its high adsorptive capacity and diffusion rate.

Heterogeneously catalysed production of isosorbide tert-butyl ethers

Isosorbide tert-butyl ethers (ITBE) have been produced by the acidic ion exchange resin-catalysed etherification of biogenic isosorbide with tert-butanol as well as with isobutene, resulting in high boiling liquids.

Comparison between Ethanol and Diethyl Carbonate as Ethylating Agents for Ethyl Octyl Ether Synthesis over Acidic Ion-Exchange Resins

Direct addition of bioethanol to diesel reduces the quality of commercial blends. An alternative way to introduce bioethanol into diesel is as linear ether such as ethyl octyl ether (EOE). EOE synthesis by 1-octanol (OcOH) reaction with ethanol (EtOH) or diethyl carbonate (DEC) over acidic ion-exchange resins has been studied in a 100-mL batch reactor (130–150 °C, 25 bar). The main drawback for ethylating OcOH in both reaction systems is the loss of ethyl groups by diethyl ether formation. In OcOH excess, selectivity to EOE with respect to EtOH and to DEC was found to be similar (58–59%) when the ethylating agent was entirely consumed. However, the initial reaction rate of EOE formation from DEC is lower, due to the formation of ethyl octyl carbonate as reaction intermediate. Accordingly, EtOH showed to be more interesting ethylating agent to produce a synthetic biofuel such as EOE over acidic ion-exchange resins.

Adsorption and Desorption of Praseodymium (III) from Aqueous Solution Using D72 Resin

In this work, the feasibility of using a macroporous strong acid ion exchange resin (D72) as an adsorbent for praseodymium (III) was examined. The adsorption behavior and mechanism were investigated with various chemical methods and IR spectrometry. The results showed that the loading of Pr (III) ions was strongly dependent on pH of the medium and the optimal adsorption condition is in HAc-NaAc medium with pH value of 3.0. Adsorption kinetics of Pr (III) ions onto D72 resin could be best described by pseudo-second-order model. The maximum adsorption capacity of D72 for Pr (III) was evaluated to be 294 mgg−1 for the Langmuir model at 298K. The apparent activation energy, Ea, was 14.71 kJmol−1. The calculated data of thermodynamic parameters, ΔSΘ value of 100 Jmol−1K−1 and ΔHΘ value of 8.89 kJmol−1, indicate the endothermic nature of the adsorption process, while a decrease of ΔGΘ with increasing temperature indicates the spontaneous nature of the adsorption process. Finally, Pr (III) can be eluted by using 1.00 mol·L−1 HCl-0.50 mol·L−1 NaCl solution and the D72 resin can be regenerated and reused. Thomas model was successfully applied to experimental data to predict the breakthrough curves and to determine the characteristic parameters of the column useful for process design. The characterization before and after adsorption of Pr (III) ions on D72 resin was conformed by IR.

Selective Synthesis of 1‐O‐Alkyl(poly)glycerol Ethers by Catalytic Reductive Alkylation of Carboxylic Acids with a Recyclable Catalytic System

(Poly)glycerol monoethers were synthesized in good yield and selectivity by the catalytic reductive alkylation of glycerol, diglycerol, and triglycerol with readily available, cheap and/or bio-sourced carboxylic acids. The reaction was catalyzed by 1 mol % of Pd/C under 50 bar H(2) using an acid ion-exchange resin as a recyclable cocatalyst. The catalytic system was recycled several times, and a mechanism is proposed for this transformation.

ChemInform Abstract: Ca[PO2(NH)3(CO)2]2 — The First Biuretooxophosphate with a Divalent Cation.

AbstractThe title compound is synthesized by room temperature ion exchange of an aqueous solution of NH4[PO2(NH)3(CO)2] with CaCl2 followed by evaporation of the solvent (strongly acidic ion exchange resin Amberlyst 15 loaded with CaCl2, 74% yield).

Etherification of Glycerol by tert-Butyl Alcohol: Kinetic Model

The catalytic etherification of glycerol with tert-butyl alcohol over a strong acid ion-exchange commercial resin (Amberlyst 15) has been studied. The etherification reactions were carried out in a glass laboratory autoclave reactor with magnetic stirring without solvent at autogenous pressure. Experimental results were obtained at different temperatures (50–80 °C) and using an 8.5 wt % catalyst loading referred to the starting amount of glycerol. Four ethers (two monoethers and two diethers) and isobutylene were identified as the main products of glycerol etherification and tert-butyl alcohol dehydration (secondary reaction), respectively. Two simplified heterogeneus kinetic models are proposed to describe the process performance. The first model lumps the monoethers and diethers into the species M and D, respectively, and includes three reactions and the corresponding kinetic equations. The second model includes all of the species detected and six stoichiometric equations. Kinetic parameters for each ki...

Sorption of Ampholytes in Weakly Acidic Ion Exchangers: Effect of Resin Ionic Form on Betaine Uptake

In this article, sorption mechanisms of glycine betaine and some related compounds on a weak cation exchanger has been studied. The effect of resin ionic form on the distribution coefficients was measured and the results correlated with a model including ion exchange, specific adsorption, and non-specific partitioning. Model calculations suggest that the maximum in the betaine uptake curve is predominantly due to ion exchange. Adsorption of the protonated and zwitterionic forms of betaine was included to improve correlation with experimental data away from the maximum. Assumptions made in the model were tested against uptake data of other model compounds.

Purification of IgG and albumin from human plasma by aqueous two phase system fractionation

The current shortages in human plasma products at global levels justify the development of new, cost effective plasma fractionation methods. We have developed a fractionation process to obtain immunoglobulin G (IgG) and albumin-enriched fractions based on polymer-salt aqueous two phase system (ATPS). A small-scale (0.02 L) ATPS composed of polyethyleneglycol 3350 (PEG), potassium phosphate and sodium chloride, at pH 6.1, was evaluated and subjected to 50-fold scale-up (1 L). Further purification of the fractions was performed using caprylic acid precipitation and ion exchange chromatography. Similar yield and purity were obtained at both small and large scales. IgG precipitated in the PEG rich upper phase at 83% recovery and 2.75-fold purification factor. An 81% pure albumin fraction was obtained in the salt rich bottom phase with a 91% yield. After polishing, IgG was obtained at a recovery of 70% and a purity of 92%. Corresponding values for albumin were 91% and 90%. This IgG and albumin fractionation technology deserves further evaluation as it may represent a potential alternative to conventional plasma fractionation methods.

Metal catalysis with nanostructured metals supported inside strongly acidic cross-linked polymer frameworks: Influence of reduction conditions of AuIII-containing resins on metal nanoclusters formation in macroreticular and gel-type materials

Synthesis of gold nanoclusters inside strongly acidic ion exchangers, in beaded forms, is carried out under different conditions. After metallation with [Au(en)2]Cl3 and reduction with H2 in the absence of any added aqueous phase, Au0/▪-SO3H nanocomposites are produced that are compared with Au0/▪-SO3− Na+ ones obtained with NaBH4 as reductant in aqueous medium. Reduction conditions allow control of both distribution and size of the metal nanoclusters. Metal distribution inside the polymer beads appears to be quite homogeneous under the hydrogen reduction conditions and metal nanoclusters size turns out to be size-controlled in the 3–5nm range. In the case of the action of NaBH4 in water, metal distribution inside the polymer beads appears to be quite peripheral and the metal nanoclusters turn out to be size-controlled but definitely larger, 5–7nm, than those obtained by action of molecular hydrogen.

Catalytic etherification of glycerol to produce biofuels over novel spherical silica supported Hyflon® catalysts

Etherification of glycerol (GLY) with isobutylene (IB) to produce biofuels was investigated in liquid phase using spherical silica supported Hyflon® catalysts (SSHC). As reference catalyst, Amberlyst® 15 (A-15) acid ion-exchange resin was used. Experiments were carried out in batch mode at a reaction temperature ranging from 323 to 343K. SSHC were found to be very effective systems in etherification of glycerol with IB, providing cumulative di- and tri-ethers yields higher than that obtained by using A-15 catalyst. Furthermore, such catalysts were stable and easily reusable; no leaching of active phase was observed. The formation of poly-substituted ethers, suitable additives for conventional fuels, was favored by operating at an isobutylene/glycerol molar ratio >3 and low reaction time (<6h); however, the concentration of mono-ether reached values lower than 3wt.% only when SSHC catalyst was used. Turnover frequency of glycerol (TOFGLY) highlighted that SSHC systems were much more active than A-15 catalyst: the accessibility and nature of active sites and the surface properties of catalysts were indicated as the main factors affecting the catalytic behavior. A lower acid site density of SSHC than that of A-15 catalyst was decisive in preventing the occurrence of oligomerization reaction which leads to the formation of di-isobutylene (DIB), precursors of gummy products.

Removal of free fatty acids in Pongamia Pinnata (Karanja) oil using divinylbenzene-styrene copolymer resins for biodiesel production

Recently biodiesel is produced from refined/edible oils using methanol and alkaline catalyst. However, wide range of non-edible oils are available, the alkaline transesterification of these oils is difficult due the presence of large amount of free fatty acids (FFA). Hence these free fatty acids form soap with alkali, it is mandatory to reduce FFA present in non-edible oils. Acidic ion exchange resins can be used to decrease FFA level. In this study, activities of resins (Amberlite IR 120 H, Amberjet 1200 H) in direct esterification of FFA present in Karanja oil were examined; the acid value was reduced ≤2 mg/KOH. The optimum conditions of esterification such as catalyst amount, methanol to oil ratio, and reaction time are chosen as 0.8% (w/w), 1:6 and 25 min for Amberlite IR 120 H and 1% (w/w), 1:6, and 25 min for Amberjet 1200 H. This pretreatment reduces the complexity of the process and the production cost of biodiesel by alkaline catalyzed transesterification.

Ion exchange membranes as electrolyte for high performance Li-ion batteries

High ionic conductivity exceeding 10−3 S cm−1 at room temperature is achieved with lithiated perfluorinated sulfonic acid (PFSA-Li) ion exchange membranes by swelling in nonaqueous organic solvents. The dependence of ionic conductivity on the membrane equivalent weight, solvent uptake, solvent properties including viscosity and dielectric constant and temperature is investigated for PFSA-Li membranes. The high performance of Li-ion battery using the PFSA-Li membranes as both electrolyte and separator is demonstrated. This new battery shows very good thermal stability and cyclic performance as compared to conventional Li-ion battery using organic liquid electrolytes. At 55 °C, this battery shows less than 3% discharge capacity loss over 120 cycles, however battery with liquid electrolyte decreased to 76% of the initial capacity after 80 cycles.

Cation Exchange Equilibria with Chromium (III) Species by Strong Acid Ion Exchangers

The exchange of hydrogen ions for trivalent chromium species with strongly acidic exchange resins has been investigated. The experiments comprised of systems with chromium chloride and basic chromium sulphate which are applied in leather tanning. Exchange equilibria at ambient temperature were investigated as a function of pH and total chromium concentration. Exchange strongly depends on the speciation in each system. As can be expected, with chromium chloride solutions a strong preference of chromium species occurs. However, a complete pattern is found for systems with basic chromium sulphate where chromium species are not fully preferred.