Loading in 2 Seconds...
Loading in 2 Seconds...
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Patent Pending Report of Research Progress In 2003 Dr. Junhang Dong (PI) Dr. Robert Lee (Manager) Mr. Liangxiong Li (Ph.D. student) Dr. Xuehong Gu (Postdoc) Petroleum Recovery Research Center (PRRC) New Mexico Institute of Mining and Technology
ACKNOWLEDGEMENTS New Mexico Tech: the president’s office provided $100K for equipment DOE: funding through the NPTO in NETL under contract No. DE-FC26-00BC15326
PRRC/NM Tech:Delivery is our Job #1 • A research arm of New Mexico oil and gas industry, only for oil and gas industry, dedicated to industry’s interests alone. • PRRC/NM Tech research directions are governed by its advisory board members including: (1) New Mexico Oil & Gas Association (NMOGA) (2) Independent Producers Association (IPANM) (3) New Mexico Oil Conservation Division (NMOCD) (4) New Mexico State Land Office (NMSLO) • NMOGA, IPANM, NMOCD, and SLO are policy-making organizations but PRRC/NM Tech is for research only.
Acknowledgement • NPTO/NETL/DOE • State of New Mexico (Governor, Senators, Representatives) • NM Tech President Office (Dr. Lopez) • NMOGA, IPANM, NMOCD, and SLO • (Bob Gallagher, Deborah Seligman, Jeff Harvard, • Tucker Bayless, Lori Wrotenbery, and Jami Baily) • PRRC Separation group members: • Dr. Junhang Dong (group leader) • Ashlee Ryan • Xuehong Gu • Aditi Majumdar • Katsuya Sugimoto • Amber Woodyatt • Liangxiong Li
Presentation Plan • PART I: Desalination of Produced Water • Supported clay membranes • Zeolite membranes • PART II: CO2 Separation By Clay Membranes • Development of PILC membranes for high temperature CO2 capture • Preliminary results on plain clay membranes • PART III: Nonoxidative CH4 Conversion • Concept of the new catalytic membrane • Proof of concept
PART I Desalination of Produced Water • Supported Clay Membranes • Zeolite Membranes
Previous Work 1. Compacted bentonite membranes as thin as 60mm were prepared. 2. Desalination was demonstrated on compacted clay membranes. 3. Problems: — Not suitable for produced water due to the rapidly diminishing ion rejection with increasing ion concentration. — Too brittle to be practical. — Extremely low flux due to thickness. Stainless steel mold for mounting the compacted clay membrane • For practical applications, • supported, thin membranes must • be developed Schematic showing the mechanism of desalination on clay membranes
Membrane Synthesis Route 1. Dispersion 2. Washing & centrifuging 3. Freeze drying Refining of clay nanoparticles (dia.< 50 nm) from commercial powders Redispersion of nanoparticles PVA Binder Dip-coating or slip-casting pH control Controlled drying: 40oC, ~60%RH Colloidal suspension for membrane coating: 0.7 wt% clay + 0.05 wt% PVA pH = ~7.5 Calcination: 0.5oC/min; 450 - 600oC
SEM Pictures of the Alumina-Supported Clay Membrane Cross-section Surface Membrane thickness = 2 ~ 3 mm BET surface area = ~ 60 m2g-1 Mesopore volume = ~ 0.075 cm3g-1 Mean pore size = 5 ~ 9 nm
Material Characterizations TEM image of the clay membrane particle size: dia. < 50 nm XRD patterns. A – a-alumina substrate, B – refined powders fired at 600°C, C – a-alumina-supported clay membrane fired at 600°C
The RO Desalination System The I.C. The cell
Results of RO Desalination for a 0.1M NaCl Solution Rejection: pf is the applied pressure.
Comparison Between Supported Membrane and Compacted Membranes * CP – compacted membrane; SP – supported membrane
Conclusions for Clay Membranes 1. Supported mesoporous clay membranes have been synthesized for the first time 2. The supported thin membranes is superior to the compacted membrane: - Mechanical strength - Rejection comparable to the compacted - High flux and low operation pressure 3. Clay membranes are less likely to succeed in the real world - Structurally unstable in aqueous conditions (swelling) - Rejection lost in high concentration solution 4. Potentially excellent for CO2 and other gas separation 5. Need new membrane with separation mechanisms not inhibited by high concentration
Film formation Nucleation Crystal growth Zeolite Membranes • Separation mechanisms • Molecular sieving • Selective adsorption • Diffusion • Current synthesis methods • In situ crystallization • Seeding/secondary growth • Vapor-phase transport • Extensively studied for gas separations • Not explored for RO desalination MFI dp: 5.6Å
Computer simulation showed 100% Na+ rejection on • zeolite-A perfect membranes • RO test for EtOH/water separation on A-type zeolite • membrane Two types of pores in polycrystalline membranes: (1) Intracrystal pore (zeolitic) and (2) intercrystal pores Rejection of hydrated ion by molecular sieving effect through intracrystal pores Rejection by overlapping double layers in intercrystal pores
MFI Membranes Synthesized by Different Methods MFI membrane synthesized by in situ crystallization method (templated). 5 mm MFI membrane synthesized by seeding-secondary growth. No template used
Microstructure Evolution for Supported MFI Membranes During Template Removal Illustration of an intercrystal pore Mismatch of thermal expansion between the MFI layer and substrates Strong bonding between zeolite layer and support formed prior to H.T. (e.g. on alumina)
Water Flux and Na+ Rejection as Functions of OR Operation Time for the 0.1M NaCl Solution Flux 50% higher than supported clay membranes Rejection almost twice as high as that on supported clay membranes
Ion Rejection as a Function of Operation Time for a Multicomponent Feed Solution Feed composition NaCl 0.1M KCl 0.1M NH4Cl 0.1M CaCl2 0.1M MgCl2 0.1M (Total ~ 80,000ppm) Overall rejection (stabilized) ~ 80% Stabilized water flux ~ 0.6 - 0.12 kg/m2 h
New Synthesis Method: Wet Gel VPT-Seeding and Secondary Growth Step 1 Wet gel VPT Step 2 Secondary growth 5 mm
Summary for Zeolite Membranes 1. First demonstration of RO desalination on zeolite membranes 2. Highly stable structure and unique separation mechanism - Can handle high concentration (produced water) - Can tolerate organic materials - High rejection and flux 3. Issues that need further investigation - Zeolite with different pore size - Minimize intercrystal pores and thickness - Better understanding of separation mechanism and effects of operation conditions - Tests with real produced water - Finding cheap way to fabricate membrane 4. Promising results obtained on a new synthesis method of VPT and secondary growth - Better reproducibilty - Higher success ratio (low cost)
PART II CO2 Separation with Clay Membranes • A new type of PILC membrane for high • temperature CO2 separation • Preliminary results on plain bentonite • membranes
Current Status • High temperature CO2 capture is the key to realizing CO2 • sequestration strategies. • Current industrial methods are not economical. • Membrane approach is energy-saving, thus the future direction. • - Polymeric membrane for T<150oC • - Organic-inorganic composite membrane for • T<300oC but has low permeability • - Ceramic membranes for T>300oC but has very low selectivity, S<2 • Challenge: developing highly CO2-selective, porous • inorganic membranes
Requirements for A Porous Ceramic Membrane — Theoretical Analysis ASSUMPTIONS: i) Chemisorption of CO2 and negligible N2 adsorption; ii) Single layer adsorption, q = Kp. iii) CO2 transport via surface diffusion with minimized Knudsen flow THEORETICAL MODEL CO2 permeability of surface diffusion (Ps) Permeability of Knudsen diffusion (PK) Selectivity (Sc) of CO2/N2 for a 50/50 feed
Calculated CO2/N2 separation on mesoporous membranes (dp=10nm, thickness=10mm) — influence of adsorbing strength (assuming negligible viscous flow) * Based on data of Horiuchi et al., 1996.
Requirements for A Porous Ceramic Membrane (1) Pore diameter < 1 nm to inhibit Knudsen diffusion and increase the selectivity. (2) Optimal CO2 adsorbing strength to maximize the permeability and selectivity. (3) Large microporous surface area to enhance the surface diffusion permeability Ideal scenario of adsorption-diffusion membrane separation
The Proposed Microporous PILC Membrane (1) Established membrane synthesis method. (2) Controllable pore size between 4Å to 30Å by adjusting pillaring materials. (3) Adjustable surface adsorbing strength, from physical adsorption to chemisorption, by ion-doping and pillaring. Surface modification by alkali metal oxides
Test of CO2 Separation on Plain Clay Membrane (1) Weak adsorption — adsorption heat: 15 - 33 kJ/mol. (2) Mesoporous (6-9nm) — Knudsen flow is significant. (3) Adsorption of CO2 on the pore surface slows down the transport of CO2. (4) Membrane in good quality — indicated by selectivity greater than Knudsen factor. (5) Microporous PILC membranes needs to be developed. Separation of a 50(CO2)/50(N2) mixture on the mesoporous bentonite membrane
PART III Novel Catalytic Membrane for CH4 Conversion to C2+ and H2 • Concept • Catalytic membranes synthesis • Preliminary results
Background 1. DOE and the energy industry seek more efficient and cleaner new technology for natural gas conversion to H2 and C2+ 2. Oxidative membrane reactor — membrane instability, low conversion at high selectivity; emission of CO2, high reaction temperature >850oC … 3. Direct CH4 conversion Advantages: - 100% selectivity - Low operation temperature, 250~450oC - Zero CO2 emission … Disadvantages: - Thermodynamically limited two-step process - Endothermic and very low equilibrium conversion
Principle of Nonoxidative CH4 Conversion Pulse Feed Reactor A new membrane reactor must be developed to overcome the two-step limitation and the thermodynamic barrier
Mechanism of the New Catalytic Membrane Feed side Membrane Permeate side Illustration of continuous operation of single-step CH4 conversion through a zeolitic channel
The Experimental System MS Pt-Co/NaY NaY only Reactor
Proof of Concept Results of CH4 conversion on Pt-Co/NaY Membrane A: The main product of conversion on the Pt-Co/NaY membrane is C3H8, which accounts for ~80% of the total C2+. Membrane deactivated in ten min due to excessive carbon formation on the catalyst surface — significantly longer than in pulse feed reactor (<one min). B: On a NaY membrane without catalyst under identical conditions. No intensity change at m/e=44 (C3H8) was observed, proving that C3H8 was generated in a single-step, continuous manner on the Pt-Co/NaY membrane. CH4 C3H8 CH4
Nonoxidative In Situ Membrane Regeneration Using H2 to rehydrogenate reactive carbon deposit 1. Minor increases in the intensities of m/e = 30 (C2H6), 44 (C3H8), 58 (C4H10), 72 (C5H12) were observed within the first 10 minutes after introducing CH4 into the feed. 2. In about 120 minutes after introducing CH4, significant increases in conversion rate of m/e = 30 (C2H6), 44 (C3H8), 58 (C4H10), 72 (C5H12). 3. The results suggest that (i) the carbon deposit was in reactive forms; (ii) activation of Co might take longer time than Pt; and (iii) the Pt-Co bimetallic catalyst had higher catalytic activity than single metal (Pt). 4.Deactivation significantly reduced.
Summary for PART III First realization of direct conversion of CH4 into C2+ and H2 by Continuous Operation • The new type of metal-loaded zeolite membrane, e.g. Pt- • Co/NaY membranes, can overcome the two-step limitation • of nonoxidative CH4 conversion into C2+ and H2. • Other metal-loaded microporous membranes, e.g. • microporous silica membranes, microporous pillared clay • membranes, and microporous carbon membranes, etc., may • also be used for such purpose. • A breakthrough in the area of nonoxidative CH4 conversion. • This invention may lead to a completely new technology for • efficient conversion of natural gas into more valuable higher • hydrocarbons and hydrogen.
THANK YOU ! Questions/suggestions ??