Patents by Inventor Stephen C. Stem

Stephen C. Stem 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: 4982048
    Abstract: This invention relates to a process for increasing the octane of a refinery gasoline pool by segregating components of a feed stream to increase the value of select components by isomerization and to prevent isomerization of other components already having a high octane value. The preferred feed stream of this process comprises di-branched paraffins, mono-methyl-branched paraffins and normal paraffins. Two or more different separatory sieves are used prior to isomerization. A first separatory shape-selective molecular sieve has a pore size of 4.5.times.4.5A or smaller to adsorb normal paraffins. A second separatory shape-selective molecular sieve has a pore size of 5.5.times.5.5 to 4.5.times.4.5A but excluding 4.5.times.4.5A. These sieves may be situated in a series flow arrangement. Normal paraffins are adsorbed by the first sieve. Mono-methyl-branched paraffins are adsorbed by the second sieve.
    Type: Grant
    Filed: February 24, 1989
    Date of Patent: January 1, 1991
    Assignee: Shell Oil Company
    Inventors: Stephen C. Stem, Wayne E. Evans
  • Patent number: 4855529
    Abstract: This invention relates to a process for increasing the octane of a refinery gasoline pool by segregating components which are increased in value by isomerization from those which are diminished in octane value by isomerization. The preferred feed stream of this process comprises di-branched paraffins, mono-methyl-branched paraffins and normal paraffins from which mono-methyl-branched and normal paraffins are selectively captured by a shape-selective molecular sieve. The preferred separatory shape-selective molecular sieve has a pore size of 5.5.times.5.5 to 4.5.times.4.5A but excluding 4.5.times.4.5A. Mono-methyl-branched paraffins and normal paraffins are removed from the shape-selective molecular sieve and isomerized in an isomerization zone to form di-methyl branched paraffins. An isomerization zone effluent stream is produced comprising unisomerized normal paraffins, mono-methyl-branched paraffins and di-branched paraffins.
    Type: Grant
    Filed: April 25, 1988
    Date of Patent: August 8, 1989
    Assignee: Shell Oil Company
    Inventors: Stephen C. Stem, Wayne E. Evans
  • Patent number: 4804802
    Abstract: This invention relates to a process for the production of an isomerate gasoline blending component where the octane value of the isomerate is increased relative to prior art processes utilizing single separatory sieves. After respective isomerization of feed streams comprising C.sub.6 or C.sub.6.sup.+ normal paraffins, a multiple separatory sieve is located to selectively adsorb unreacted normal paraffins and mono-methyl-branched paraffins from an isomerate product stream. The preferred first separatory sieve is exemplified by a calcium 5A sieve which can adsorb normal paraffins while allowing mono-methyl-branched paraffins and more higly branched paraffin to pass to a second separatory sieve. The second sieve comprises a shape-selective zeolite having a pore size intermediate 5.5.times.5.5 and 4.5.times.4.
    Type: Grant
    Filed: January 25, 1988
    Date of Patent: February 14, 1989
    Assignee: Shell Oil Company
    Inventors: Wayne E. Evans, Stephen C. Stem
  • Patent number: 4717784
    Abstract: This invention relates to a process for the production of an isomerate gasoline blending component where the octane value of the isomerate is increased relative to the overall cost of the process. After isomerization, the separatory sieve of this invention selectively adsorbs unreacted normal paraffins and mono-methyl-branched paraffins but not di-methyl-branched paraffins. The preferred separatory sieve is ferrierite. This process is an improvement over prior Total Isomerization Processes (using a calcium-5A separatory sieve) to recycle only n-paraffins to the isomerization zone.
    Type: Grant
    Filed: December 10, 1986
    Date of Patent: January 5, 1988
    Assignee: Shell Oil Company
    Inventors: Stephen C. Stem, Wayne E. Evans
  • Patent number: 4622130
    Abstract: This invention discloses an economic series flow dewaxing scheme having a first solvent dewaxing step followed by a catalytic dewaxing step. The use of methylisopropyl ketone as a key component in the solvent dewaxing step produces a solvent dewaxed effluent with an intermediate pour point which may be readily catalytically dewaxed to a pour point suitable for lubricant applications. The catalytic dewaxing unit can also be used to recover lost oil yield from the soft wax product of the solvent dewaxing zone (sometimes referred to as footsoil) and thereby sustain, if not increase, overall lubricating oil yield.
    Type: Grant
    Filed: December 9, 1985
    Date of Patent: November 11, 1986
    Assignee: Shell Oil Company
    Inventor: Stephen C. Stem