DOCSLIB.ORG

Application of Nanosize Zeolite Molecular Sieves for Medical Oxygen Concentration

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Application of Nanosize Zeolite Molecular Sieves for Medical Oxygen Concentration nanomaterials Article Application of Nanosize Zeolite Molecular Sieves for Medical Oxygen Concentration Mingfei Pan, Hecham M. Omar and Sohrab Rohani * Department of Chemical and Biochemical Engineering, Faculty of Engineering, University of Western Ontario, London, ON N6A 5B9, Canada; [email protected] (M.P.); [email protected] (H.M.O.) * Correspondence: [email protected]; Tel.: +1-519-661-4116 Received: 19 June 2017; Accepted: 21 July 2017; Published: 25 July 2017 Abstract: The development of a portable oxygen concentrator is of prime significance for patients with respiratory problems. This paper presents a portable concentrator prototype design using the pressure/vacuum swing adsorption (PVSA) cycle with a deep evacuation step (−0.82 barg) instead of desorption with purge flow to simplify the oxygen production process. The output of the oxygen concentrator is a ~90 vol % enriched oxygen stream in a continuous adsorption and desorption cycle (cycle time ~90 s). The size of the adsorption column is 3 cm in diameter and 20 cm in length. A Li+ exchanged 13X nanosize zeolite is used as the adsorbent to selectively adsorb nitrogen from air. A dynamic model of the pressure and vacuum swing adsorption units was developed to study the pressurization and depressurization process inside the microporous area of nanosized zeolites. The describing equations were solved using COMSOL Multiphysics Chemical Engineering module. The output flow rate and oxygen concentration results from the simulation model were compared with the experimental data. Velocity and concentration profiles were obtained to study the adsorption process and optimize the operational parameters. Keywords: nanosize zeolite; microporous adsorption; bidisperison dynamic model; portable oxygen concentrator; COMSOL Multiphysics 1. Background Air pollution is becoming a worldwide problem particularly in heavily populated cities like Beijing, Los Angeles, and Mexico City. Air pollution leads to acute and chronic respiratory problems that are becoming a growing concern from both global and individual levels. Wearing disposable face masks has become a popular method to get some protection from exposure to pollutants. However, for people with poor autonomous respiration ability, like chronic obstructive pulmonary disease (COPD) patients, it is hard to breathe through disposable face masks. As a result, there is a growing need to address the health and quality of life through a light-weight and portable oxygen concentrator with a medical grade oxygen supply (O2 concentration: ~88–92 vol %). Currently, oxygen concentration techniques are based on air separation processes such as cryogenic technique, membrane separation and pressure swing adsorption (PSA) that can effectively produce enriched oxygen using ambient air as the source. Although cryogenic distillation acts as the leading process for air separation in an industrial oxygen plant, the pressure swing adsorption (PSA) technique has the advantage of reducing energy consumption for small production scales. Compared to the membrane separation technique, which requires higher pressure and expensive selective permeable materials, pressure swing adsorption using nanosize zeolite adsorbents is a more feasible solution for portable oxygen concentrator development. Due to the large microporous surface area inside the zeolite adsorbents, the portable oxygen concentrator using the PSA technique can adsorb nitrogen from air and output an enriched oxygen stream under high-pressure conditions. The concentrator can be regenerated by Nanomaterials 2017, 7, 195; doi:10.3390/nano7080195 www.mdpi.com/journal/nanomaterials Nanomaterials 2017, 7, 195 2 of 19 decreasing the pressure to release the adsorbed nitrogen. In this way, a continuous oxygen stream supply can be generated to assist an individual and increase the fraction of inspired oxygen. The oxygen concentration system is usually coupled with a filtration system to remove PM 2.5 and improve the quality of product gas stream. The pressure swing adsorption process was patented by Finlayson and Sharp in 1932 (GB Patent 365092) describing an air separation process with pressurization adsorption and depressurization desorption steps [1]. In 1958, two different pressure swing adsorption units were patented: one using fractional product purge flow for desorption step (Skarstrom, 1958) and the other using pressure vacuum adsorption (PVSA) step (Montgareuil and Domine, 1958) [2,3]. The selectivity for zeolite adsorbents to adsorb nitrogen compared to oxygen is due to the interaction between electrostatic field of the cationic zeolite and the quadrupole moment of the nitrogen and oxygen. The quadrupole of nitrogen is three times higher than that of oxygen, which leads to a selective adsorption onto the zeolite surface [4]. The most common type of commercial zeolite for oxygen concentration process is zeolite 13X due to its outstanding nitrogen to oxygen adsorption selectivity. However, 13X zeolite modified with Li+ exchange method exhibits a higher nitrogen adsorption capacity at the active cation sites of the zeolite framework [5–7]. JLOX-101 LiX zeolite provided by LUOYANG JIANLONG Chemical is designed specifically for a PVSA process with high oxygen selectivity [8]. The PSA system was first installed in industrial plants as a replacement for cryogenic separation plants due to lower capital and operating costs. Portable pressure swing adsorption oxygen concentrators have been designed and developed in the past two decades due to the synthesis of more effective zeolites with higher gas adsorption capacity and selectivity. The PSA oxygen concentrator is able to provide a continuous oxygen flow using the ambient air as the gas source. Two-bed or multi-bed PSA systems are utilized alternating adsorption and desorption operations of the zeolite columns to achieve continuous oxygen separation. For on-site medical grade oxygen production, a cylinder gas source or several powerful air compressors are usually installed for the rapid pressure swing adsorption process to maintain the productivity of high purity oxygen stream [9–11]. Considering the mobility of small-scale concentrators, a variety of simplified designs would be added to the pressure swing adsorption process for system miniaturization. In this paper, we compare the performance of a portable miniature PVSA oxygen concentrator unit with two adsorption columns, an air compressor, four solenoid valves and a back-pressure regulator (total weight less than 2 kg) built in our laboratory with the simulation results under modified Montgareuil and Domine cycle using COMSOL Multiphysics Chemical Engineering module. Compared to the conventional PSA cycle using purge flow with intermediate evacuation pressure (−0.6 barg) to regenerate the adsorption column, the deep vacuum (−0.82 barg) desorption step of the PVSA cycle reduces the column and compressor size from the perspective of industrial prototype design. A dual-head air compressor is selected to generate pressure and vacuum condition simultaneously for the dual-column adsorption unit, which simplifies the gas source generation. The oxygen concentrator unit can provide a ~90 vol % enriched oxygen stream to meet the concentration requirement of medical-grade oxygen. 2. Materials and Methods Figure1 shows the schematic of the oxygen concentrator using a two-column PVSA cycle. The concentrator consists of two adsorption zeolite columns, a dual-head air compressor (Parker Hannifin Corp., TTC IIS Miniature Diaphragm Pump, Hollis, NH, USA), five three-way solenoid valves (Parker Hannifin Corp., X-Valve, Hollis, NH, USA), a back-pressure regulator, an oxygen sensor (Teledyne GB300 Oxygen analyzer, Thousand Oaks, CA, USA), a surge tank, a pressure sensor (Freescale Semiconductor, MPXV7002DPT1CTND, Austin, TX, USA) and a cooling fan (avoiding the temperature rise of the air compressor) [12–15]. The oxygen sensor is an electrochemical transducer named Micro-fuel Cell calibrated by the Faraday type calibration method based on the product gas Nanomaterials 2017, 7, 195 3 of 19 from electrolysis of water [16]. The valve sequence is shown in Table1. The concentrator operation consists of four different steps. In step 1, column 1 is pressurized by the compressor while column 2 is connected to ambient air to decrease the pressure. In step 2, the pressure inside column 1 reaches the working pressure (1.79 barg) with enriched oxygen flowing out through the backpressure regulator (set at 1.79 barg) to the surge tank. Meanwhile the pressure in column 2 decreases to vacuum (set Nanomaterials 2017, 7, 195 3 of 19 at −0.82 barg) via the air compressor to regenerate the zeolite. In steps 3 and 4, the adsorption and desorptionthe working positions pressure of (1.79 column barg) 1with and enriched 2 are reversed oxygen toflowing regenerate out through the saturated the backpressure column 1 and pressurizeregulator the regenerated (set at 1.79 barg) column to the 2. Bysurge switching tank. Meanwhile the valve the sequence pressure (stepin column 1 ! 42 !decreases1), a continuous to enrichedvacuum oxygen (set stream at −0.82 can barg) be obtainedvia the air fromcompressor the surge to regenerate tank. The the flow zeolite. directions In steps of 3 theand two4, the different adsorption and desorption positions of column 1 and 2 are reversed to regenerate the saturated types ofcolumn valves 1 (normallyand pressurize open the and regenerated distributor column three-way 2. By switching solenoid the valve valves) sequence are shown (step 1 in → Figure4
Load more

Recommended publications
  • Molecular Sieve
    Molecular Sieve Theory, Properties, and Process Optimization Hi Did you know that Molecular Sieves are… Type A • used in dehydration units or beds • also called zeolite and mole sieve • tiny, hollow crystals that separate smaller molecules from larger molecules • able to selectively adsorb Water Molecule size = 2.8A molecules due to pore diameter Molecular Sieve Pore size = 3A of the crystals Ethanol Molecule size = 3.6A You’ve probably ...this is seen its beaded or Molecular Sieve beaded form… in its crystal form Process of Making Molecular Sieve Sieve Purpose Why use Molecular Sieve • 3A Molecular Sieve breaks the ethanol/water azeotrope • Finishes dehydrating ethanol after distillation and removes final 5% of water • Allows ethanol to be used as a fuel additive Common Bed Layouts How to read a Specification Sheet How to read a Specification Sheet How to read a Specification Sheet How to read a Specification Sheet How to read a Specification Sheet THINGS TO LOOK FOR… TIME FOR A CHANGE • Frequent filter changes If you’re experiencing • Caused by dust in system these situations and you • Weak beads break and crack over time hope for improvement, • High regeneration proof you should talk to your • Caused by loss of adsorption capacity ethanol community for a • 3A can change back to 4A solution. • Rapid changes in Pressure Drop The opportunities for • Can be caused by wide bead optimization are endless. distribution • Broken and cracked beads cause irregularities • Reductions of Cycle Times Process Optimization WORKING CAPACITY • Capacity
    [Show full text]
  • Adsorption Basics: Part 2
    Back to Basics Adsorption Basics: Part 2 Alan Gabelman, P.E. This article focuses on adsorbents, including Gabelman Process Solutions, LLC activated carbon, zeolite molecular sieves, and polymeric adsorbents, as well as ion exchange resins. dsorption is a unit operation that exploits the attrac- batch mix tank, because the high pressure drop precludes its tion of solutes in a liquid or gas to a solid surface. use in a column. Spent powdered carbon must be removed AThis attraction allows the solutes to be removed, or by filtration, and regeneration is not practical. solutes with different affinities for the solid to be separated. Activated carbon is a highly versatile adsorbent, because The first article (1) of this two-part series presented the its performance characteristics can be tailored by varying fundamentals of adsorption, including equilibrium and mass- the precursor, roasting conditions, and activation method. transfer considerations, the mass-transfer zone concept, Consequently, products are available for a wide range of breakthrough, regeneration, and column sizing. This article, applications, for treating both gases and liquids. Liquid Part 2, covers the most widely used adsorbents — in order of applications include potable water treatment (discussed decreasing commercial importance (2, 3): activated carbon, later), groundwater remediation, industrial and municipal zeolite molecular sieves, silica gel, activated alumina, and wastewater treatment, sweetener decolorization, and chemi- polymeric adsorbents — with discussion of their physi- cal and pharmaceutical processing. Examples of gas appli- cal characteristics, suitable applications, and regeneration cations are removal of organics from waste gas, capture of requirements. Ion exchange, a process that is similar gasoline vapor emissions from automobiles, and adsorption to adsorption and is used to remove ions from solution, is of gaseous radionuclides from nuclear power plants.
    [Show full text]
  • Tuning Carbon Molecular Sieve Membrane Performance for Challenging Gas Separations
    TUNING CARBON MOLECULAR SIEVE MEMBRANE PERFORMANCE FOR CHALLENGING GAS SEPARATIONS A Dissertation Presented to The Academic Faculty by Graham B. Wenz In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in Chemical Engineering Georgia Institute of Technology May 2017 COPYRIGHT © 2017 BY GRAHAM B. WENZ TUNING CARBON MOLECULAR SIEVE MEMBRANE PERFORMANCE FOR CHALLENGING GAS SEPARATIONS Approved by: Dr. William J. Koros, Advisor Dr. Ryan P. Lively School of Chemical and Biomolecular School of Chemical and Biomolecular Engineering Engineering Georgia Institute of Technology Georgia Institute of Technology Dr. Peter J. Ludovice Dr. Pradeep K. Agrawal School of Chemical and Biomolecular School of Chemical and Biomolecular Engineering Engineering Georgia Institute of Technology Georgia Institute of Technology Dr. Meisha L. Shofner School of Material Science and Engineering Georgia Institute of Technology Date Approved: April 3rd, 2017 This work is dedicated to my parents. ACKNOWLEDGEMENTS This has been a journey with many ups and downs, and would not have been possible without the support of many people. First and foremost, I have to express my sincere gratitude to my advisor, Dr. William J. Koros. I am almost certain that I will never meet another human being more dedicated to their work. His combination of endless energy (coffee probably helps here), depth of knowledge and desire to “push the boundaries” has been, and will continue to be, inspirational. I can certainly say that without his guidance and support, I would not have made it to this point. I would also like to thank my Ph.D. committee members: Dr. Pradeep K. Agrawal, Dr.
    [Show full text]
  • Sorption and Activation of Hydrocarbons by Molecular Sieves Johannes a Lercher* and Kulathuiyer Seshant
    57 Sorption and activation of hydrocarbons by molecular sieves Johannes A Lercher* and Kulathuiyer Seshant Substantial progress has been made recently in the report of the reactions and catalyst performance is not understanding of sorption and activation of alkanes. This attempted. progress reflects the emergence of new theoretical and experimental results, leading to a more quantitative picture Adsorption of hydrocarbons of the elementary steps involved in the ordering of alkanes Structural and energetic aspects of alkane adsorption in molecular sieves and their chemical interaction with the It is commonly accepted that alkanes are primarily acid site. Conversion of n-alkanes over various zeolites is now bound by dispersive interactions to the molecular sieve well understood to depend mainly upon the concentration walls, independently of the presence or absence of of reactants sorbed. The sorption enthalpy and entropy of Br6nsted or Lewis acids sites (see for example [1°]). these molecules are linearly related and this relationship is These dispersive interactions lead to a generally weak characteristic of a particular molecular sieve (compensation perturbation of the alkane C-H bonds; the perturbation effect). The interfacial chemistry that alkanes and alkenes has been experimentally observed by IR spectroscopy undergo involves ionic species only in their transition state, [Z',3]. whereas the stable intermediates are covalently bound. This leads to a description of the chemical transformations that The energy of interaction (e.g. represented by the heat resemble nucleophilic and electrophilic substitutions. of adsorption) between aikanes and molecular sieves in- creases with the number of carbon atoms of the adsorbate. For molecular sieves that constrain molecule-molecule Addresses interactions, this increase is a linear function of the University of Twente, Faculty of Chemical Technology, PO Box 217, 7500 AE Enschede, The Netherlands number of carbon atoms, for alkanes with similar structure *e-mail: [email protected] (e.g.
    [Show full text]
  • Integrated Testing of a 4-Bed Molecular Sieve and a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization
    041CES-299 Integrated Testing of a 4-Bed Molecular Sieve and a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization James C. Knox Marshall Space Flight Center, NASA Lila M. Mulloth, David L. Affleck Science Applications Intl.Corp. Copyright 0 2004 SAE International ABSTRACT ATMOSPHERE REVITALIZATION SUBSYSTEM Accumulation and subsequent compression of carbon As part of the International Space Station (ISS) growth to dioxide that is removed from space cabin are two support six to seven crewmembers, development is important processes involved in a closed-loop air underway of a Sabatier COS Reduction assembly. A revitalization scheme of the International Space Station 4BMS is currently on the ISS Destiny module for removal (ISS). The 4-Bed Molecular Sieve (4BMS) of ISS of metabolic COS. An identical 4BMS is being prepared currently operates in an open loop mode without a for Node 3. These and other elements of the Node 3 compressor. This paper reports the integrated 4BMS and environmental control and life support system (ECLSS) liquid-cooled TSAC testing conducted during the period are shown in Figure 1. Those elements pertaining to this of March 3 to April 18, 2003. The TSAC prototype was paper are described in the following paragraphs. developed at NASA Ames Research Center (ARC)'. The 4BMS was modified to a functionally flight-like pondition Air at NASA Marshall Space Flight Center (MSFC) . Testing was conducted at MSFC. The paper provides details of the TSAC operation at various COS loadings and corresponding performance of CDRA. INTRODUCTION The TSAC is a candidate technology to provide buffering of the carbon dioxide (C02) stream between the 4BMS and the Sabatier components, part of a closed loop atmosphere revitalization system (ARS).
    [Show full text]
  • Molecular Sieve Adsorbents for Ethanol Processing Zeochem Products for the Ethanol Processing Industry Zeochem Products for the Ethanol Processing Industry
    Adsorption Technologies: our work – our life – our passion. Molecular Sieve Adsorbents for Ethanol Processing Zeochem Products for the Ethanol Processing Industry Zeochem Products for the Ethanol Processing Industry ZEOCHEM® Z3-03 for Ethanol Dehydration Zeochem, a manufacturer of high Zeochem is a world leader in quality molecular sieves and chroma- supplying molecular sieves for tography gels, was established more the ethanol dehydration market. than 190 years ago and its head- Over 70% of the ethanol plants quarters is still based at the original in the USA and Brazil have been location on Lake Zurich, Switzerland. supplied with our ZEOCHEM® Zeochem is a subsidiary of the Swiss Z3-03 molecular sieve. Through CPH Chemie+Papier Holding AG. the years and through our process of continuous improvements, With manufacturing facilities in ZEOCHEM® Z3-03 continues to Uetikon, Switzerland and Louisville, be the performance standard KY, USA, Zeochem provides coordinated for molecular sieves in ethanol global supply and support to all dehydration. molecular sieve adsorbent markets. This is particularly important today with complex plant requirements and services needed worldwide. High Quality Manufacturing ZEOCHEM® Z3-03 is the potassium The spherical shape of the product form of the A type zeolite structure ensures that all physical forces and has an effective pore opening of applied are compressive in nature. 3 angstroms (0.32 nm). This molecular Molecular sieve adsorbents are much sieve is designed for high water stronger under compressive forces content in the feed stream, elevated as compared to the tensile forces temperatures, and quick cycling — acting on extruded (rod or pellet) all factors inherent in the ethanol shapes.
    [Show full text]
  • Separation of Ethanol-Water Mixture Using Type-A Zeolite Molecular Sieve
    ISSN: 0973-4945; CODEN ECJHAO E-Journal of Chemistry http://www.e-journals.net 2010, 7(2), 483-495 Separation of Ethanol-Water Mixture Using Type-A Zeolite Molecular Sieve JUAN CAMILO DÍAZ, IVÁN DARÍO GIL-CHÁVEZ, LILIANA GIRALDO § and JUAN CARLOS MORENO-PIRAJÁN * Departamento de Ingeniería Química, Facultad de Ingeniería, Universidad de los Andes, Bogotá, Colombia. §Facultad de Ciencias, Departamento de Química, Universidad Nacional de Colombia. *Facultad de Ciencias, Departamento de Química, Grupo de Investigación en Sólidos Porosos y Calorimetría, Universidad de Los Andes, Bogotá, Colombia. Received 3 June 2009; Accepted 1 August 2009 Abstract: This paper presents an experimental procedure for the synthesis of a type-A zeolite molecular sieve, usable in the separation of an ethanol-water mixture. The type-A zeolite molecular sieve is obtained from a reactive mixture formed by a source of alumina, a source of silica and a promoter. Characterization of the molecular sieves obtained in this work was undertaken using X-ray diffraction (XRD), adsorption isotherms and scanning electron microscopy (SEM). The results from the characterization procedures showed that part of the product presented a pore diameter suitable for the separation of an ethanol-water mixture. Keywords : Molecular sieve, Adsorption, Zeolite, X-ray diffraction, Scanning electron microscopy. Introduction The great quantity of toxic gaseous emissions produced from combustion engines may cause diseases and contribute to the global warming of the planet. This fact, coupled with the decline in global oil reserves, has made necessary the research and use of alternative renewable energy sources in order to provide a solution to these problems.
    [Show full text]
  • High Diversity of Microplankton Surrounds Deepwater Coral Reef In
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by ResearchOnline at James Cook University RESEARCH ARTICLE High diversity of microplankton surrounds deep-water coral reef in the Norwegian Sea Sigmund Jensen1, David G. Bourne2, Martin Hovland3,4 & J. Colin Murrell5 1Department of Biology, University of Bergen, Bergen, Norway; 2Australian Institute of Marine Science, Townsville, Qld, Australia; 3Centre for Geobiology, University of Bergen, Bergen, Norway; 4Ambio ASA, Stavanger, Norway; and 5School of Environmental Sciences, University of East Anglia, Norwich, UK Correspondence: Sigmund Jensen, Abstract Department of Biology, University of Bergen, Norway. Tel.: +4755584400; fax: Coral reefs that exist in the depths of the oceans are surrounded by Eukarya, +4755584450; e-mail: Archaea and bacterial communities that may play an important role in the [email protected] nutrition and health of the reef. The first interdomain community structure of planktonic organisms in seawater from a deep-water coral reef is described. Received 20 January 2012; revised 24 April Community profiling and analysis of ribosomal RNA gene sequences from a 2012; accepted 6 May 2012. coral reef system at 350 m depth in the Norwegian Sea revealed a rich diversity Final version published online 25 June 2012. of Eukarya and Bacteria and a moderate diversity of Archaea. Most sequences DOI: 10.1111/j.1574-6941.2012.01408.x affiliated with marine microplankton from deep-sea to cold-surface regions, with many sequences being similar to those described in studies of mesopelagic Editor: Gary King and oxygen minimum zones. Dominant phylotypes belonged to the Alveolata (group I, II, dinoflagellates), Stramenopiles (silicoflagellates), Alphaproteobacteria Keywords (Pelagibacter ubique), Gammaproteobacteria (ARCTIC96BD-19), Bacteroidetes deep-water coral reef; microplankton; (Flavobacteria) and mesophilic Crenarchaeota (Nitrosopumilus maritimus).
    [Show full text]
  • PRESSURE SWING ADSORPTION in the UNIT OPERATIONS LABORATORY Jason C
    ChE laboratory PRESSURE SWING ADSORPTION IN THE UNIT OPERATIONS LABORATORY Jason C. Ganley Colorado School of Mines • Golden, CO 80401 ressure swing adsorption (PSA) is an industrial process adsorption occurs. The selection of a particular type of ad- typically used for the bulk separation of gas mixtures. sorbent may allow one component of a gas mixture to be An outgrowth of temperature swing adsorption, PSA preferentially adsorbed, the nature of surface and/or pore dif- Pis one of only a few gas-surface adsorption processes that fusion effects may vary for each gas in the mixture, and so on. allows for the separation of mixtures of gaseous species or PSA is a cyclic operation, and generally involves separa- vapors that exist in relatively high (non-trace) concentra- tion of a gas mixture by taking advantage of differences in tions in respect to one another. PSA has also been coupled adsorption thermodynamics or in diffusion rates that exist for to distillation processes for the separation of alcohol-water its various components. Cycling between higher and lower [1] vapor azeotropes. pressures allows components of the gas mixture to be removed It is interesting to note that, despite serving an important from (and later released to) the gas phase over designated pe- role for many decades in the chemical process industry, PSA riods of time. Students in the Unit Operations Laboratory may is not a central topic discussed in most chemical engineering consider the PSA cycle primarily as a mass transfer (rather educational resources, which instead focus on mass transfer than heat transfer) experiment.
    [Show full text]
  • Comparison of Water-Removal Efficiency of Molecular Sieves
    fermentation Article Comparison of Water-Removal Efficiency of Molecular Sieves Vibrating by Rotary Shaking and Electromagnetic Stirring from Feedstock Oil for Biofuel Production Cherng-Yuan Lin * and Lei Ma Department of Marine Engineering, National Taiwan Ocean University, Keelung 202, Taiwan; [email protected] * Correspondence: [email protected] Abstract: Adequate water-removal techniques are requisite to remain superior biofuel quality. The effects of vibrating types and operating time on the water-removal efficiency of molecular sieves were experimentally studied. Molecular sieves of 3 Å pore size own excellent hydrophilic characteristics and hardly absorb molecules other than water. Molecular sieves of 3 Å accompanied by two different vibrating types, rotary shaking and electromagnetic stirring, were used to remove initial water from the reactant mixture of feedstock oil in order to prevent excessive growth or breeding of microorganisms in the biofuel product. The physical structure of about 66% molecular sieves was significantly damaged due to shattered collision between the magnetic bar and molecular sieves during electromagnetic stirring for 1 h. The molecular sieves vibrated by the rotary shaker appeared to have relatively higher water-removal efficiency than those by the electromagnetic stirrer and by keeping the reactant mixture motionless by 6 and 5 wt.%, respectively. The structure of the molecular sieves vibrated by an electromagnetic stirrer and thereafter being dehydrated appeared much more Citation: Lin, C.-Y.; Ma, L. irregular and damaged, and the weight loss accounted for as high as 19 wt.%. In contrast, the Comparison of Water-Removal Efficiency of Molecular Sieves structure of the molecular sieves vibrated by a rotary shaker almost remained original ball-shaped, Vibrating by Rotary Shaking and and the weight loss was much less after regenerative treatment for those molecular sieves.
    [Show full text]
  • Properties of Molecular Sieve Membranes
    : LICENTIATE T H E SI S Properties of Molecular Sieve Membranes Charlotte Andersson Luleå University of Technology Department of Chemical Engineering and Geosciences, Division of Chemical Technology :|: -|: - -- ⁄ -- Properties of Molecular Sieve Membranes Charlotte Andersson Division of Chemical Technology Department of Chemical Engineering and Geosciences Luleå University of Technology November 2004 Abstract Zeolites are crystalline aluminosilicates with molecular sieving properties and are widely used in industry for catalysis, sorption and ion-exchange applications. Zeolite membranes are commercially interesting since this technology may be employed for continuous separation of molecules under severe conditions. MFI zeolite has suitable pore diameter for many applications and relatively high thermal and chemical stability. Zeolite films in membranes must be thin, to obtain a high flux and free from defects for high selectivity. Many parameters are affecting the properties of zeolite films and in this thesis some of them are investigated. MFI zeolite membranes were prepared using seed crystals and hydrothermal synthesis and characterized with scanning electron microscopy, single gas permeation measurements, porosimetry and separation experiments. Membranes grown in one or several steps with seeding in-between the synthesis steps were compared. It was observed that membranes comprised of small crystals and consequently high concentration of grain boundaries had low separation performance. Grain boundaries could also be opened by extensive
    [Show full text]
  • Separation of High Purity Nitrogen from Air by Pressure Swing Adsorption on Carbon Molecular Sieves
    International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 3 Issue 3, March - 2014 Separation of High Purity Nitrogen from Air by Pressure Swing Adsorption on Carbon Molecular Sieves Snehal V. Patel Dr. J. M. Patel P.G. Student, Mechanical Dept. Associate Professor in Cryogenics Dept. L.D.College of Engineering, L.D.College of Engineering, Ahmedabad, India. Ahmedabad, India. Abstract— Nitrogen is produced mainly from its most The main criteria for choosing suitable process of air abundant source, the air, using three processes: membrane, separation are: selection between O2 or N2 as the main pressure swing adsorption (PSA) and cryogenic distillation. By product, process operating conditions (flow rate, high or low considering the operating conditions, flow rate and purity of pressure, desired phase of product (gas or liquid)), purity of Nitrogen, the most economic technology for separation of product, and energy cost. For several years, nitrogen was Nitrogen from the air can be chosen. Of course for some values of produced from air by cryogenic distillation, and more recently purity and flow rate, more than one technology can be selected. In these ranges, other parameters such as economic value of by- by pressure swing adsorption (PSA). Often, the latter products phase of delivered product fluid (liquid or gaseous) and technology involves the use of carbon molecular sieve (CMS) the product applications should be taken into account. Onsite adsorbents packed in two beds [5]. nitrogen generators, such as pressure swing adsorption (PSA) or membrane systems, can be more cost effective than traditional The original idea of using pressure swing to separate air cryogenic distillation or stored liquid nitrogen, particularly if an was disclosed in a patent by Skarstrom and independently, in a extremely high purity (e.g., 99.9999%) is not required.
    [Show full text]