Santi Kulprathipanja

• Chulalongkorn University

Effects of tetrahydrofuran (THF) concentration on the mixed methane hydrate formation, dissociation, and stability were investigated. The experiment was conducted at 286.2 K and 6 MPa in a quiescent reactor. The presence of THF below 2.5 mol% did not show the evidence of hydrate formation. However, the concentration above 2.5 mol% enhanced the meth...

This report reveals the success of the formation of mixed methane-THF hydrates at room temperature (298.2 K) and a pressure of 9.2 MPa equipped with a hybrid stirring in the presence of amino acids as kinetic promoters. Five different amino acids in increasing order of hydrophobicity: glutamic acid, valine, leucine, methionine, and tryptophan, were...

Effects of co-promoters on the mixed methane-THF hydrate formation in the presence of 3.5 wt% NaCl and 5.56 mol% THF solution were investigated at 8 MPa and 288.2 K in an unstirred reactor. The addition of NaCl resulted in the two-step hydrate formation, and it is the first stage that adversely affected the hydrate formation rate. However, the fina...

Solidified natural gas (SNG) via clathrate hydrates has been proposed as an alternative approach for natural gas storage and transportation. In this work, the roles of 5.56 mol% pyrrolidine were investigated for the methane hydrate formation in terms of thermodynamics and kinetics along with morphology. The results showed that pyrrolidine generally...

Application of amino acids to copromote methane hydrate formation with tetrahydrofuran (THF) and their effects on the dissociation were investigated at room temperature. Hydrophobic side chain amino acids (valine, leucine, and methionine) were experimented together with 5.56 mol% THF on the hydrate formation kinetics and morphology at 293.2 K and 8...

The influence of activated carbon (AC) particle size on the formation and dissociation of CO2 hydrates was investigated. ACs with different particle sizes (250-420 µm; 420-841 µm; larger than 841 µm) were employed in the hydrate formation experiment at 276.2 K and 3.6 MPa in the quiescent condition. The result showed that the large AC particle size...

Foam generation from the presence of sodium dodecyl sulfate (SDS) as a kinetic promoter in methane hydrate formation can be potentially reduced by using mixed surfactants. Mixtures of SDS with nonionic surfactants was proposed to solve this problem. Polyoxyethylene (n) lauryl ether (EO3 and EO5) and alkyl poly glycol ether (APG) were chosen to mix...

Two widely investigated methane hydrate promoters, tetra-n-butyl ammonium bromide (TBAB) and cyclopentane (CP), for methane hydrate formation and dissociation were comparatively investigated in the quiescent reactor at 2.5 °C and 8 MPa. The results indicated that the increase in the mass fraction TBAB decreased the induction time. However, it did n...

Solidified natural gas (SNG) technology via hydrates is a promising and potential method for storing natural gas. It offers a compact mode of natural gas storage with high degree of safety. In this work, we present the synergistic effects of tetrahydrofuran (THF), hollow silica (HS) and sodium dodecyl sulfate (SDS) in enhancing the kinetics of mixe...

Sodium dodecyl sulfate (SDS) markedly improved tetrahydrofuran (THF) - assisted methane hydrate formation. Firstly, methane hydrate formation with different THF amount, 1, 3, and 5.56 mol%, was studied. SDS with 1, 4, and 8 mM was then investigated for its roles on the methane hydrate formation with and without THF. The experiments were conducted i...

Effects of three different reduction environments on the preparation of Cu(I)X and Cu(I)Y zeolites and their adsorption selectivity towards propylene were investigated. Cu(I)X and Cu(I)Y zeolites were prepared by ion exchange of NaX and NaY zeolites with ammoniacal copper solution, which were reduced in ammonia (1 h and 2 h) or hydrogen flow. Resul...

CO2 adsorption of polybenzoxazine-modified activated carbon prepared by grafting various polybenzoxazine (PBZ) via ring-opening polymerization of different amine precursors was investigated. Benzoxazine monomer (BZ) was synthesized from phenol, paraformaldehyde, and hexamethylenediamie (HMDA) or triethylenetetramine (TETA). The PBZ loading was vari...

Hydrogen desorption/absorption of the LiBH4/MgH2 mixture milled for 5 h was investigated with different initial pressures. The results showed that the initial pressure played an important role in the reversibility of the LiBH4/MgH2 mixture. The stability of the hydrogen capacity in the subsequent desorption was improved with a higher initial pressu...

BACKGROUND Polybenzoxazine (PBZ) membranes have caught great attention for serving as a high performance membrane for pervaporation process owing to their high mechanical properties, high chemical resistance, high thermal stability, and low synthesis cost. This study aims to develop PBZ membrane and NaA-PBZ mixed matrix membrane (MMM) for purificat...

A method for separating a xylene from a feed mixture by contacting the feed mixture with a bed of adsorbent comprising metal organic framework crystals selective to the xylene.

Effects of H2SO4 and KOH treated activated carbon and tetrahydrofuran (THF) on methane hydrate formation kinetics were investigated in a fixed volume crystallizer at 6 and 8 MPa and 277.15 K. The addition of the untreated activated carbon enhanced the kinetics of the hydrate formation at 8 MPa, while adding the carbon treated by H2SO4 and KOH incre...

A thorough investigation on hydrogen desorption of MgH2 and its reversibility with the focus on effects of a catalyst (TiCl3, TiO2, ZrCl4, and ZrO2) were reported. The experiments were carried out using a Sievert's type apparatus. The reaction kinetics and the phase transformation behaviours were examined using a differential scanning calorimeter (...

This study compared the methane adsorption on activated carbon with and without the treatment with sulphuric acid (H2SO4) and potassium hydroxide (KOH) and metal organic frameworks (MOFs)-Basolite C300 and Basolite Z1200. In the experiment, methane gas was pressurized up to 500 psia and the temperature was set at 303 K. The results showed that, gra...

This work studied the effects of activated carbon and tetrathydrofuran (5.56 mol % THF) on methane hydrate phase equilibrium and hydrate dissociation. The hydrate formation was carried out in the quiescent condition and close system at 4 °C. After completion of hydrate formation, the hydrate dissociation was observed by thermal stimulation. The pre...

Effects of different polyethyleneimine (PEI) molecular weights on CO2 adsorption on activated carbon (AC) were investigated. The PEI loading was varied using different PEI initial concentrations from 1 to 5 g/L. CO2 adsorption isotherms were investigated at 30 and 75 °C. Adsorbents were characterized by TG-DTA, FTIR, and surface area and pore size...

SUMMARY TiCl3 has been considered as the best catalyst for the hydrogen desorption/re-absorption of NaAlH4 in terms of kinetic enhancement. However, the formation of NaCl as a by-product leads to the decrease in the reversible hydrogen capacity of NaAlH4. In this work, TiO2 and metallic Ti were selected as catalysts for the reaction to avoid the fo...

This paper examines the effect of metal loading (Zr-, V-, Ti-, and K-compounds) on the hydrogen storage property of mechanically milled graphite. The hydrogen adsorption took place at room temperature and 11 MPa measured by thermal volumetric analysis. The results showed that the graphite loaded with ZrCl4 provided a maximum hydrogen storage capaci...

A mixed matrix adsorbent is found for use in the removal of light alkanes from a gasoline stream. The mixed matrix comprises two adsorbents with one adsorbent having an LTA type structure and the other adsorbent having an MFI structure.

Conventional azeotropic distillation, consuming very high energy, is mostly used to produce high purity ethanol for renewable energy usage. In this study, the techno-economic comparison between azeotropic distillation (distillation followed by practical azeotropic distillation) and hybrid system (distillation followed by pervaporation system) for p...

Among the tested carbons, only carbon aerogels (CAs) had significant effects on the hydrogen desorption behavior of LiAlH4. Adding 15 wt % CAs decreased the desorption temperature, while, with 5 wt % CAs, the desorption temperature was still the same. The desorption kinetics of the hydride with 15 wt % CAs, however, did not improve but adding 5 wt...

The hydrogen desorption/absorption behaviors of LiAlH4/LiBH4 with a focus on the effects of catalysts, namely TiCl3, TiO2, VCl3, and ZrCl4, were investigated using a thermal-volumetric apparatus. The hydrogen desorption was performed from room temperature to 300 °C with a heating rate of 2 °C min⁻¹. The LiAlH4–LiBH4 mixture with a molar ratio of 2:...

Membrane separation process using NaA zeolite membrane is a good alternative process for ethanol production in terms of both energy consumption and environmental friendliness. However, the highest cost for the membrane separation process is from the membrane production step. The reduction of the membrane production cost by optimization of the synth...

The performance of sodium A (NaA) zeolite membranes with a surface area of 4.91cm2, synthesized on an alumina support via microwaving (MW) and autoclaving (AC, or conventional heating) using the recycle-continuous pervaporation of a water–ethanol mixture (10:90vol.%), was studied. It was found that the process could produce ethanol having a concent...

The hydrogen desorption/absorption of the 2:1 mole ratio of LiBH4 and MgH2 with and without a catalyst was investigated. In the case of the uncatalyzed LiBH4/MgH2 mixture, the first hydrogen desorption started at 50 °C. The amount of released hydrogen was 8.6 wt% at the first hydrogen desorption and dramatically reduced to 1.8 wt% at the tenth hydr...

Sodium aluminum hydride or sodium alanate (NaAlH4) has been considered as a potential material for hydrogen storage. Although its theoretical hydrogen storage capacity is 5.5wt.% at 250°C, the material still has its drawback in the regeneration issue. With the use of certain catalysts, the regeneration problem can somewhat be alleviated with added...

The present invention relates to a membrane contactor assisted extn. system and method for extg. a single phase species from multi-phase working solns. More specifically one preferred embodiment of the invention relates to a method and system for membrane contactor assisted water (MCAWE) extn. of hydrogen peroxide (H2O2) from a working soln. [on Sc...

IntroductionImpacts of Adsorptive Separation Versus Other Separation ProcessesLiquid Phase AdsorptionModes of OperationZeolite Separation ProcessesSummaryAcknowledgmentsReferences

The effect of Ti compounds on H2 desorption/absorption of LiNH2/LiAlH4/MgH2 was investigated. The formation of NH3 from the decomposition of LiNH2 was suppressed by adding LiAlH4 and MgH2 to LiNH2. In addition, the onset desorption temperature of LiNH2/LiAlH4/MgH2 was lower than that of pure LiNH2, whose onset desorption temperature is approximatel...

This work presents the synthesis and characterization of multi-walled carbon nanotubes (multi-walled CNTs) deposited with Pd or V and their hydrogen storage capacity measured by Sievert's volumetric apparatus. The CNTs were grown by the CVD method using LPG and LaNi5 as the carbon source and catalyst, respectively. Pd was impregnated on the CNTs by...

Chloronitrobenzenes (CNBs) are important organic intermediates that are used practically for azos, sulfur dyes, pesticides, fungicides, and in rubber chemical industries. Many separation and purification techniques, such as distillation, crystallization, and adsorption, have been investigated to achieve the highest purity and conversion of CNB. In...

In general, hydrophilic NaA zeolite membranes are used for dehydration of organic solvent. The membranes can be synthesized on alumina support by three different heating methods, namely, microwave, electrophotoresis and autoclave (or conventional heating). Performance and the formation of this zeolite membrane were analyzed using pervaporation tech...

Solid hydrogen storage materials have been investigated as hydrogen carriers due to their safety in hydrogen applications. In contrast, they also have some disadvantages, such as a low hydrogen capacity, very high desorption/adsorption temperature, low kinetic rate, and low reversibility. Many attempts have been made to improve and identify materia...

Mixed matrix membranes (MMMs) have been considered as an alternative gas separation technique due to their low energy consumption and high selectivity. In previous studies, it was found that silicon rubber MMMs incorporated with polyethylene glycol (PEG) and some diol isomers such as 1,2-, 1,3-, 1,4- and 2,3-butanediol can improve the selectivity a...

Effects of catalysts (Ti, TiO2, and TiCl3) on hydrogen desorption of a 2:1 molar ratio of LiBH4:MgH2 and its reversibility were investigated. 3 mol% of a Ti-compound were added as a catalyst in the hydride mixture using mechanical ball-milling for one hour as a mixing means. Hydrogen desorption was carried out under atmospheric pressure with the te...

The segregation of bulk Al after the hydrogen desorption may be one of many reasons why there is the incomplete hydrogen re-absorption and the need for higher desorption temperature in subsequent desorption of HfCl4- and TiO2-doped NaAlH4. In this work, we attempted to improve hydrogen storage capacity of 4 mol% HfCl4- and 4 mol% TiO2-doped NaAlH4...

The concept of fabricating hollow fibers with double-layer mixed-matrix materials using the same polymeric matrix has been demonstrated for gas separation. Polyethersulfone (PES)–beta zeolite/PES–Al2O3 dual-layer mixed-matrix hollow fiber membranes with enhanced separation performance have been fabricated. This study presents an innovative approach...

Influences of seven solvents – benzene, toluene, ethylbenzene (EB), p-diethylbenzene (pDEB), o-xylene, m-xylene, and p-xylene – on the production of high purity 2,6-dimethylnaphthalene (DMN) via catalytic isomerization and adsorptive separation of the 2,6-triad DMNs were investigated. The solvents act as a reaction media for the isomerization and a...

IntroductionLiquid-Phase Adsorption Versus Other Separation ProcessesLiquid-Phase Adsorption MechanismsAdsorbentsSurvey of Liquid SeparationModes of OperationCommercial Liquid-Separation ProcessesFuture Developments

Recently, zeolite membranes on porous supports have been extensively studied in the ethanol–water separation process for further use for gasohol production. This work focuses on a NaA membrane synthesized on an α-Al2O3 support via microwave hydrothermal treatment. Synthesis temperature and time, type of substrate, seed amount and seeding time for t...

In this study, an alternative non-energy intensive system for the production of 2,6-DMN (catalytic isomerization in a solvent media and adsorptive purification) was investigated using the pulse test technique. The integrations of the isomerization to the adsorption were accomplished in two different approaches; subsequent adsorption after the isome...

The main objective of this work was to investigate the effect of two transition metals (0–9 mol% ZrCl4 and HfCl4) on hydrogen desorption/absorption of NaAlH4 and LiAlH4. The hydrogen desorption was carried out over a wide temperature range of 25– while the hydrogen absorption took place at and between 50– for NaAlH4 and LiAlH4, respectively, with t...

Effects of tin incorporation in titanium silicalite-1 (TS-1) on the kinetic modelling of phenol hydroxylation to dihydroxybenzenes with aqueous hydrogen peroxide have been investigated. The modelling of the hydroxylation reaction was from the results of a batch reactor, minimizing mass transfer conditions. The kinetic analysis indicates that under...

Gas separation by selective transport through polymeric membranes is one of the fastest growing branches of membrane technology. However, the existing polymeric membrane materials are inadequate to fully exploit the application opportunities on industrial scale; the improvement in permeability is at the expense of selectivity, and vice versa. A new...

A novel silver ion-exchange treatment of zeolite was introduced in this work to change the physical and chemical adsorption properties of penetrants in the zeolite. EDX data confirm the complete replacement of sodium ion in zeolite NaA by silver ion, whereas XRD patterns and BET results show no changes in some physical properties of zeolite after t...

The main objective of this work was to investigate the different effects of transition metals (TiO2, VCl3, HfCl4) on the hydrogen desorption/absorption of NaAlH4. The HfCl4 doped NaAlH4 showed the lowest temperature of the first desorption at 85 °C, while the one doped with VCl3 or TiO2 desorbed at 135 °C and 155 °C, respectively. Interestingly, th...

Nano-sized Na A zeolite was successfully synthesized via the sol–gel process and microwave techniques. The synthesis parameters, such as hydroxide ion concentration, seed amount, as well as heating time and temperature, were studied to obtain the most uniform and very small sized NaA zeolite using the composition of SiO2:Al2O3:xNa2O:410H2O; 3 ≤ x ≤...

The polymer–zeolite mixed matrix membranes were fabricated by incorporating nanosized or microsized zeolite 4A into polyethersulfone. A comparison of zeolite 4A nanocrystals and microcrystals was made by using SEM, XRD, N2 adsorption–desorption measurements. Zeolite particles were well-distributed in the polymer phase, as reflected by the SEM image...

Catalytic isomerization of 1,5- to 2,6-dimethylnaphthalene (DMN) over H-beta zeolite was carried out in a continuous flow fixed bed system by using toluene as a solvent in this study. Feed flow rates, reaction temperatures and feed concentrations were varied to investigate their effect on the isomerization in the presence of the solvent. Interestin...

Adsorption of the equilibrium mixture of 1,5-, 1,6- and 2,6-dimethylnaphthalene (DMN) was investigated on a series of alkaline and alkaline earth ion-exchanged faujasite zeolites using pulse test and breakthrough techniques. It was found that the adsorption of the DMNs would proceed through a complex mechanism governing by at least molecular diffus...

Without Abstract

It has been demonstrated that a novel p-xylenediamine/methanol soaking method could efficiently remove the polymer–zeolite interface defects of the mixed-matrix structure. In this work, the mixed-matrix structure is in the form of an ultrathin (1.5–3 μm) polysulfone/zeolite beta mixed-matrix layer that is supported by a neat Matrimid® layer in dual...

Dual-layer PES/P84 hollow fiber membranes with a PES–zeolite beta mixed matrix dense-selective layer of 0.55μm have been successfully fabricated in this study by adjusting the ratio of outer layer flow rate to inner layer flow rate during the spinning with the aid of heat-treatment at 235°C and two-step coating. To our best knowledge, this is the t...

Hollow fibers with a thin zeolite beta-polysulfone mixed matrix selective layer and enhanced selectivity for He/N2 and O2/N2 separation have been developed in this study. It is believed that the heat treatment and the coating processes combine to bring out the separation properties of zeolite beta imbedded in the polymer matrix. The fibers were ini...

In this study, a series of three-layer zeolite-embedded poly(vinyl alcohol) (PVA) composite membranes have been successfully fabricated with a casting machine. Zeolites, examined with a loading of 20 wt%, include 3A, 4A, 5A, NaX, NaY, silicalite and beta. These hydrophilic composite membranes have been evaluated in the dehydration of ethanol aqueou...

Effect of light intensity on the phenol hydroxylation using hydrogen peroxide (H2O2) as an oxidant and titanium silicalite-1 (TS-1) as a catalyst was studied. Three different levels of light intensity were examined; without light, 18 and 500W light intensity. At 60°C under the 500W light intensity, phenol conversion significantly increased and reac...

A novel silane coupling agent, (3-aminopropyl)-diethoxymethyl silane (APDEMS) was used in this work to modify zeolite surface for mixed matrix membranes (MMMs). Both elementary analysis and XPS spectra confirm the chemical modification, while BET measurements show no changes in zeolite surface area and total pore volume after the modification. Poly...

We have developed multilayer mixed matrix membranes (MMMMs) consisting of a selective mixed matrix membrane (MMM) top layer, a porous poly(acrylonitrile-co-methyl acrylate) [poly(AN-co-MA)] intermediate layer and a polyphenylene sulfide (PPS) nonwoven fabrics substrate. The selective MMM layer was formed by incorporating KA zeolite in poly(vinyl al...

To alleviate the problem that the release of hydrogen from NaAlH 4 is not up to what has been expected, some transition metals have been added into the medium in order to increase the hydrogen absorption capacity and speed up the kinetics of hydrogen desorption from NaAlH 4. In this project, NaAlH 4 was purified by dissolving in THF and was precipi...

Study on liquid phase isomerization of 1,5- to 2,6-dimethylnaphthalene (DMN) was conducted in a batch reactor using acidic zolite catalysts. The effect of catalyst amount, catalyst type, and reaction temperature were investigated before thermodynamic study. The results showed that H-beta zolite was the best catalyst for the reaction. Interestingly,...

The polyethersulfone (PES)-zeolite 3A, 4A and 5A mixed matrix membranes (MMMs) were fabricated with a modified solution-casting procedure at high temperatures close to the glass transition temperatures (Tg) of polymer materials. The effects of membrane preparation methodology, zeolite loading and pore size of zeolite on the gas separation performan...

The preparation of carbon-zeolite composite membranes for gas separation, was analyzed using the pyrolysis of polymer-zeolite mixed matrix membranes (MMM). A zeolite-filled MMM was prepared through the incorporation of zeolite into a Matrimid polyimide matrix. It was observed that the selectivity and permeability of carbon-zeolite composite membran...

Although hydrogen has a great potential as clean energy, safe practical storage of hydrogen for applications such as fuel cells has been a major challenge. NaAlH4 is one of the metal hydrides, which are candidates for hydrogen storage in vehicles. However, the rather slow absorption/desorption kinetics is still a significant drawback. To alleviate...

We have revealed, for the first time, the evolution of nano-particle distribution and the mechanisms of nano-particle movement during the formation of single-layer and dual- membranes. Both single-layer and dual-layer mixed matrix hollow fibers have been fabricated using nano-size zeolite beta. It is found that three factors play important roles in...

Phenol hydroxylation with TS‐1 was studied in a chromatographic reactor. TS‐1 not only acts as the catalyst for the reaction but also the adsorbent for the separation. The reaction/separation was carried out at 60°C with water and 0.2 wt% of aqueous H2O2 as the desorbent. Separation of hydroquinone (HQ) can be achieved in all cases. With water as t...

We have developed almost defect-free Matrimid/polyethersulfone (PES) dual-layer hollow fibers with an ultra-thin outer layer of about 10 × 10−6 m (10 μm), studied the effects of spinneret and coagulant temperatures and dope flow rates on membrane morphology and separation performance, and highlighted the process similarities and differences between...

New bimetallic framework and non-framework titanium and tin silicalite have been investigated for phenol hydroxylation with H2O2 in different solvents, and the optimized catalyst composition showed 26% higher initial rate than reference TS-1.

Two types of mixed matrix membranes were developed by UOP in the late 1980s. The first type includes adsorbent polymers, such as silicalite-cellulose acetate (CA), NaX-CA, and AgX-CA mixed matrix membranes. The silicalite-CA has a CO(2)/H(2) selectivity of 5.15 +/- 2.2. In contrast, the CA membrane has a CO(2)/H(2) selectivity of 0.77 +/- 0.06. The...

Of the radioactive analogs of potassium, is one of the most attractive, particularly in institutions with positron detection devices. This is the case primarily because it is available as a radionuclide generator product by decay of its long-lived parent and, as such, does not require in-house cyclotron production. Considerable effort elsewhere has...

Several agents are currently available for blood-pool imaging with positron scintigraphy. Haemoglobin may be labelled with either by administration of 11CCO by inhalation or by intravenous administration of a sample of the subject's whole blood previously labelled by exposure to 11CCO. Since labelling with 11C requires a particle accelerator, alt...

Aus dem Ketol (I) entsteht nach verschiedenen Verfahren das Cyanhydrin (II), dessen Ausbeuten optimiert werden.

A novel method is presented for the separation of aluminum from strontium by anion exchange in the hydroxide form. When added in acidic solution, aluminum forms Al(OH) 4 − and is retained while strontium is eluted as the neutral Sr(OH)2. The procedure has been used to purify spallation-produced82Sr for use in the82Sr−82Rb radionuclide generator. It...

The influence of pH and citrate concentration on radio labeled gallium citrate has been investigated in vitro and in vivo as an aid to understanding the behavior of this radiopharmaceutical. Using paper chromatography, we have shown that a competition for gallium exists between hydroxyl and citrate ions in solution such that effective chelation occ...

The 191Os191mIr decay is suitable for construction of an ultra short lived radionuclide generator. The long lived parent ( 15.3 day) may be loaded on some column support such that the short lived daughter ( 4.9 sec) may be selectively removed and used in radionuclide angiographic applications. In work related to the development of this generator,...