Patents by Inventor Liren Xu

Liren Xu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 10150840
    Abstract: Prepare a carbon molecular sieve membrane from a polyimide (e.g., a 6FDA/BPDA-DAM polyimide) that has a glass transition temperature of at least 400° C. and includes a bridged phenyl compound for separation of hydrogen and ethylene from one another whether present as a pure mixture of hydrogen and ethylene or as components of a cracked gas. Preparation comprises two sequential steps a) and b). In step a), place a membrane fabricated from defect-free fibers of the polyimide in contact with an oxygen-containing atmosphere under conditions of time and temperature sufficient to produce a pre-oxidized and pre-carbonized polymeric membrane that is insoluble in hot (110 C) n-methylpyrolidone and at least substantially free of substructure collapse.
    Type: Grant
    Filed: September 3, 2015
    Date of Patent: December 11, 2018
    Assignee: Dow Global Technologies LLC
    Inventor: Liren Xu
  • Publication number: 20170247512
    Abstract: Prepare a carbon molecular sieve membrane from a polyimide (e.g., a 6FDA/BPDA-DAM polyimide) that has a glass transition temperature of at least 400° C. and includes a bridged phenyl compound for separation of hydrogen and ethylene from one another whether present as a pure mixture of hydrogen and ethylene or as components of a cracked gas. Preparation comprises two sequential steps a) and b). In step a), place a membrane fabricated from defect-free fibers of the polyimide in contact with an oxygen-containing atmosphere under conditions of time and temperature sufficient to produce a pre-oxidized and pre-carbonized polymeric membrane that is insoluble in hot (110 C) n-methylpyrolidone and at least substantially free of substructure collapse.
    Type: Application
    Filed: September 3, 2015
    Publication date: August 31, 2017
    Inventor: Liren Xu
  • Patent number: 9346011
    Abstract: A hollow fiber carbon molecular sieve membrane, a process for preparing the hollow fiber carbon molecular sieve membrane, and a process for effecting separation of an olefin from a gaseous mixture that comprises the olefin in admixture with its corresponding paraffin and optionally one or more gaseous components selected from hydrogen, an olefin other than the olefin and a paraffin other than the corresponding paraffin. The process and membrane may also be used to effect separation of the olefin(s) from remaining feedstream components subsequent to an olefin-paraffin separation.
    Type: Grant
    Filed: April 29, 2013
    Date of Patent: May 24, 2016
    Inventors: William J. Koros, Liren Xu, Mark K. Brayden, Marcos V. Martinez, Brien A. Stears
  • Publication number: 20150053079
    Abstract: A hollow fiber carbon molecular sieve membrane, a process for preparing the hollow fiber carbon molecular sieve membrane, and a process for effecting separation of an olefin from a gaseous mixture that comprises the olefin in admixture with its corresponding paraffin and optionally one or more gaseous components selected from hydrogen, an olefin other than the olefin and a paraffin other than the corresponding paraffin. The process and membrane may also be used to effect separation of the olefin(s) from remaining feedstream components subsequent to an olefin-paraffin separation.
    Type: Application
    Filed: April 29, 2013
    Publication date: February 26, 2015
    Applicants: Dow Global Technologies LLC, Georgia Tech Research Corporation
    Inventors: William J. Koros, Liren Xu, Mark K. Brayden, Marcos V. Martinez, Brien A. Stears
  • Patent number: 8911534
    Abstract: Carbon molecular sieve membranes having desirable selectivity for ethylene/ethane separations are prepared from a 3,3?,4,4?-benzophenonetetracarboxylic acid dianhydride 5(6)-amino-1-(4?-aminophenyl)-1,3,3-trimethylindane 4,4-bismaleimidodiphenyl-methane (BTDA-DAPI) precursor solution that is then formed into films or hollow fibers which are pyrolyzed under vacuum or an inert atmosphere to form carbon molecular sieve membranes. Pyrolysis condition variables, including ramp rate, thermal soak time and temperature, are used to optimize the membrane's separation performance.
    Type: Grant
    Filed: February 28, 2012
    Date of Patent: December 16, 2014
    Assignee: Georgia Tech Research Corporation
    Inventors: William J. Koros, Meha Rungta, Liren Xu
  • Publication number: 20130333562
    Abstract: Carbon molecular sieve membranes having desirable selectivity for ethylene/ethane separations are prepared from a 3,3?,4,4?-benzophenonetetracarboxylic acid dianhydride 5(6)-amino-1-(4?-aminophenyl)-1,3,3-trimethylindane 4,4-bismaleimidodiphenyl-methane (BTDA-DAPI) precursor solution that is then formed into films or hollow fibers which are pyrolyzed under vacuum or an inert atmosphere to form carbon molecular sieve membranes. Pyrolysis condition variables, including ramp rate, thermal soak time and temperature, are used to optimize the membrane's separation performance.
    Type: Application
    Filed: February 28, 2012
    Publication date: December 19, 2013
    Applicant: Georgia Tech Research Corporation
    Inventors: William J. Koros, Meha Rungta, Liren Xu