Vinylidene chloride copolymer-based carbon molecular sieve adsorbent compositions and processes therefor

A technology of polyvinylidene chloride and composition, applied in the field of molecular sieve composition, capable of solving undetermined and undisclosed problems

Active Publication Date: 2017-05-31
DOW GLOBAL TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, previous researchers have not established that polyvinylidene chloride copolymer-based CMSs are capable of effectively and/or efficiently separating gas pairs of much smaller molecules, including, in a non-limiting example, C 3 h 8 /C 3 h 6 、C 2 h 6 /C 2 h 4 and/or CH 4 /N 2
[0011] Accordingly, it will be found that the prior art does not recognize carbonized PVDC having an average pore size as specified to be suitable for small molecule separation...

Method used

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  • Vinylidene chloride copolymer-based carbon molecular sieve adsorbent compositions and processes therefor
  • Vinylidene chloride copolymer-based carbon molecular sieve adsorbent compositions and processes therefor
  • Vinylidene chloride copolymer-based carbon molecular sieve adsorbent compositions and processes therefor

Examples

Experimental program
Comparison scheme
Effect test

example 1 to example 17 and comparative example 1 to comparative example 16

[0061] A series of Example (ES) and Comparative Example (CS) samples were prepared from polyvinylidene chloride copolymerized with a monomer selected from methyl acrylate (MA), ethyl acrylate (EA) or butyl acrylate (BA), whereby The monomers mentioned are present in the amounts indicated in Table 2 in each case. In each case, the copolymerization is effected by suspension polymerization. Generally, this involves mixing the selected monomers according to their weight ratio to the polymerization initiator, and then carrying out the polymerization reaction in the aqueous dispersion. The copolymer powder is then dried to remove water and any unreacted monomer. The powder was then sieved and its 30 to 50 US sieve portion selected to ensure consistency for CMS preparation.

[0062] The precursor powder was then pretreated by dehydrochlorination in an oven purged by 2 liters per minute (L / min) of air at a temperature of 130° C. for 24 hrs, followed by 150° C. for 24 hrs.

[0063] ...

example 18

[0076] shown in Table 2 with Four (4) example samples (EX) of effective pore sizes of , designated ES 1 , ES6, ES 8 and ES 13, were used in experiments to compare high-throughput kinetic adsorption in the separation of propylene and propane. To calculate the selectivity, the formula shown in equation (3) is used.

[0077]

[0078] In the equation, "ΔP" represents the pressure drop due to adsorption (from 45 psi (0.31 MPa) starting pressure to equilibrium pressure), which is proportional to the amount of adsorption according to the ideal gas law. The half-adsorption time ("t0.5") represents the time at which 50% of the pressure drop (adsorption) occurs, which corresponds to the rate of diffusion. Selectivity ("α-PD") is specified in the equation below to account for both equilibrium and kinetic selectivity. The results tested for the 4 example samples are shown in Table 3.

[0079] Table 3: CMS samples: C of ES 1, ES 6, ES 8 and ES 13 2 h 4 / C 2 h 6 Kinetic Sorption ...

example 19

[0084] Ethylene / ethane selectivity measurements were performed using the ES 11 in a high-throughput kinetic adsorption. The results of the separation are shown in Table 4. These results show that not only does ethane adsorb to a much smaller extent than ethylene in the CMS of the invention, but it also adsorbs much more slowly by a factor of about 10 due to the pressure drop produced by the adsorption. Thus, two molecules can be separated easily and efficiently using the compositions of the present invention.

[0085] Table 4: CMS Sample: C of ES 11 2 h 4 / C 2 h 6 Kinetic Sorption Summary

[0086]

[0087]

[0088] *1psi=about 0.007MPa

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Abstract

Novel carbon molecular sieve (CMS) compositions comprising carbonized vinylidene chloride copolymer having micropores with an average micropore size ranging from 3.0 to 5.0 angstroms. These materials offer capability in separations of gas mixtures including, for example, propane/propylene; nitrogen/methane; and ethane/ethylene. Such may be prepared by a process wherein vinylidene chloride copolymer beads, melt extruded film or fiber are pretreated to form a precursor that is finally carbonized at high temperature. Preselection or knowledge of precursor crystallinity and attained maximum pyrolysis temperature enables preselection or knowledge of a average micropore size, according to the equation sigma= 6.09 +(0.0275*C) - (0.00233*T), wherein sigma is the average micropore size in Angstroms, C is the crystallinity percentage and T is the attained maximum pyrolysis temperature in degrees Celsius, provided that crystallinity percentage ranges from 25 to 75 and temperature in degrees Celsius ranges from 800 to 1700. The beads, fibers or film may be ground, post-pyrolysis, and combined with a non-coating binder to form extruded pellets, or alternatively the fibers may be woven, either before or after pre-treatment, to form a woven fiber sheet which is thereafter pyrolyzed to form a woven fiber adsorbent.

Description

[0001] Cross References to Related Applications [0002] This application claims a U.S. provisional patent entitled "CARBONIZED VINYLIDENE CHLORIDE COPOLYMER-BASED MOLECULARSIEVE ADSORBENT COMPOSITIONS AND PROCESSES THEREFOR," filed June 30, 2014 Benefit of Application No. 62 / 018,828, which is hereby incorporated by reference in its entirety. technical field [0003] The present invention relates to the field of molecular sieve compositions. More specifically, it relates to carbon molecular sieve compositions based on vinylidene chloride copolymers. Background technique [0004] Over the years, researchers have sought means to separate gas mixtures for use as either starting materials or as products. A material that has attracted much attention as a means of such separations has been carbon molecular sieves (CMS). These CMSs can be prepared from a variety of resins and pyrolyzed at various temperatures and / or under various conditions. Pyrolysis reduces the resin to pure...

Claims

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Application Information

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IPC IPC(8): B01J20/28B01J20/20B01J20/30B01D53/02C01B32/306C01B32/318
CPCB01D53/02B01J20/28038B01J20/3021B01J20/3028B01J20/3078B01J20/2808B01J2220/4812C01P2006/16B01D2253/102B01D2253/116B01D2253/308B01D2253/311B01D2256/10B01D2256/24B01D2256/245B01D2257/102B01D2257/504B01D2257/7022B01D2257/7025Y02C20/20Y02P20/156B01D53/228B01D67/0067B01D69/02B01D71/34B01D2325/023B01D71/021C01B32/00C01B32/306C01B32/382B01J20/20B01J20/28016B01J20/28023B01J20/28069B01J20/3007Y02C20/40Y02P20/151B01D2325/52C01P2006/14
Inventor 刘军强D·E·拜尔E·M·卡尔弗利C·韩
Owner DOW GLOBAL TECH LLC
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