Patents by Inventor Dawid J. Duvenhage

Dawid J. Duvenhage 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: 10086366
    Abstract: A structurally promoted precipitated catalyst containing crystalline silica, at least one chemical promoter selected from the group consisting of alkali metals, and iron, the structurally promoted precipitated catalyst comprising maghemite and hematite catalytic phases, and exhibiting a main reduction peak temperature, as determined by TPR, in the range of from about 210° C. to about 350° C. A method of producing the structurally promoted precipitated catalyst is also provided.
    Type: Grant
    Filed: December 8, 2016
    Date of Patent: October 2, 2018
    Assignee: RES USA, LLC
    Inventors: Dawid J. Duvenhage, Belma Demirel
  • Publication number: 20170209852
    Abstract: A method for controllably producing a hematite-containing Fischer-Tropsch catalyst by combining an iron nitrate solution with a precipitating agent solution at a precipitating temperature and over a precipitation time to form a precipitate comprising iron phases; holding the precipitate from at a hold temperature for a hold time to provide a hematite containing precipitate; and washing the hematite containing precipitate via contact with a wash solution and filtering, to provide a washed hematite containing catalyst. The method may further comprise promoting the washed hematite containing catalyst with a chemical promoter; spray drying the promoted hematite containing catalyst; and calcining the spray dried hematite containing catalyst to provide a calcined hematite-containing Fischer-Tropsch catalyst.
    Type: Application
    Filed: April 10, 2017
    Publication date: July 27, 2017
    Inventors: Dawid J. Duvenhage, Christine Schmidt, Mark Still, Khalid Azzam, Karl C. Kharas, Sara Hunegnaw, Olga Ionkina, Ray J. Huang, Harold A. Wright
  • Patent number: 9669390
    Abstract: A method for controllably producing a hematite-containing Fischer-Tropsch catalyst by combining an iron nitrate solution with a precipitating agent solution at a precipitating temperature and over a precipitation time to form a precipitate comprising iron phases; holding the precipitate from at a hold temperature for a hold time to provide a hematite containing precipitate; and washing the hematite containing precipitate via contact with a wash solution and filtering, to provide a washed hematite containing catalyst. The method may further comprise promoting the washed hematite containing catalyst with a chemical promoter; spray drying the promoted hematite containing catalyst; and calcining the spray dried hematite containing catalyst to provide a calcined hematite-containing Fischer-Tropsch catalyst.
    Type: Grant
    Filed: February 11, 2014
    Date of Patent: June 6, 2017
    Assignee: RES USA, LLC
    Inventors: Dawid J. Duvenhage, Christine Schmidt, Mark Still, Khalid Azzam, Karl C. Kharas, Sara Hunegnaw, Olga Ionkina, Ray J. Huang, Harold A. Wright
  • Patent number: 9649610
    Abstract: A method of preparing a spray dried catalyst by combining spray dried catalyst particles with wax so the spray dried catalyst particles are coated with wax, yielding wax coated catalyst particles, and shaping the wax coated catalyst to provide shaped wax coated catalyst. A method of activating Fischer-Tropsch catalyst particles containing oxides by contacting the catalyst particles with a reducing gas in an activation vessel to produce an activated catalyst, wherein contacting is performed in the absence of a liquid medium under activation conditions. A system for activating a Fischer-Tropsch catalyst containing an activation reactor configured to introduce an activation gas to a fixed or fluidized bed of the Fischer-Tropsch catalyst in the absence of a liquid medium and at least one separation device configured to separate a gas stream comprising entrained catalyst fines having an average particle size below a desired cutoff size from the activation reactor.
    Type: Grant
    Filed: August 25, 2014
    Date of Patent: May 16, 2017
    Assignee: RES USA, LLC
    Inventors: Harold A. Wright, Belma Demirel, Sergio Mohedas, Bahman Rejai, Ray J. Huang, Deena Ferdous, Jesse W. Taylor, Dawid J. Duvenhage, Sara L. Rolfe
  • Publication number: 20170100708
    Abstract: A structurally promoted precipitated catalyst containing crystalline silica, at least one chemical promoter selected from the group consisting of alkali metals, and iron, the structurally promoted precipitated catalyst comprising maghemite and hematite catalytic phases, and exhibiting a main reduction peak temperature, as determined by TPR, in the range of from about 210° C. to about 350° C. A method of producing the structurally promoted precipitated catalyst is also provided.
    Type: Application
    Filed: December 8, 2016
    Publication date: April 13, 2017
    Inventors: Dawid J. Duvenhage, Belma Demirel
  • Patent number: 9550172
    Abstract: A structurally promoted precipitated catalyst containing crystalline silica, at least one chemical promoter selected from the group consisting of alkali metals, and iron, the structurally promoted precipitated catalyst comprising maghemite and hematite catalytic phases, and exhibiting a main reduction peak temperature, as determined by TPR, in the range of from about 210° C. to about 350° C. A method of producing the structurally promoted precipitated catalyst is also provided.
    Type: Grant
    Filed: March 30, 2015
    Date of Patent: January 24, 2017
    Assignee: RES USA, LLC
    Inventors: Dawid J. Duvenhage, Belma Demirel
  • Patent number: 9522372
    Abstract: A method of preparing a spray dried catalyst by combining spray dried catalyst particles with wax so the spray dried catalyst particles are coated with wax, yielding wax coated catalyst particles, and shaping the wax coated catalyst to provide shaped wax coated catalyst. A method of activating Fischer-Tropsch catalyst particles containing oxides by contacting the catalyst particles with a reducing gas in an activation vessel to produce an activated catalyst, wherein contacting is performed in the absence of a liquid medium under activation conditions. A system for activating a Fischer-Tropsch catalyst containing an activation reactor configured to introduce an activation gas to a fixed or fluidized bed of the Fischer-Tropsch catalyst in the absence of a liquid medium and at least one separation device configured to separate a gas stream comprising entrained catalyst fines having an average particle size below a desired cutoff size from the activation reactor.
    Type: Grant
    Filed: July 2, 2013
    Date of Patent: December 20, 2016
    Assignee: RES USA, LLC
    Inventors: Harold A. Wright, Belma Demirel, Sergio Mohedas, Bahman Rejai, Ray J. Huang, Deena Ferdous, Jesse W. Taylor, Dawid J. Duvenhage, Sara L. Rolfe
  • Publication number: 20160001267
    Abstract: A method for controllably producing a hematite-containing Fischer-Tropsch catalyst by combining an iron nitrate solution with a precipitating agent solution at a precipitating temperature and over a precipitation time to form a precipitate comprising iron phases; holding the precipitate from at a hold temperature for a hold time to provide a hematite containing precipitate; and washing the hematite containing precipitate via contact with a wash solution and filtering, to provide a washed hematite containing catalyst. The method may further comprise promoting the washed hematite containing catalyst with a chemical promoter; spray drying the promoted hematite containing catalyst; and calcining the spray dried hematite containing catalyst to provide a calcined hematite-containing Fischer-Tropsch catalyst.
    Type: Application
    Filed: February 11, 2014
    Publication date: January 7, 2016
    Inventors: Dawid J. Duvenhage, Christine Schmidt, Mark Still, Khalid Azzam, Karl C. Kharas, Sara Hunegnaw, Olga Ionkina, Ray J. Huang, Harold A. Wright
  • Publication number: 20150251167
    Abstract: A structurally promoted precipitated catalyst containing crystalline silica, at least one chemical promoter selected from the group consisting of alkali metals, and iron, the structurally promoted precipitated catalyst comprising maghemite and hematite catalytic phases, and exhibiting a main reduction peak temperature, as determined by TPR, in the range of from about 210° C. to about 350° C. A method of producing the structurally promoted precipitated catalyst is also provided.
    Type: Application
    Filed: March 30, 2015
    Publication date: September 10, 2015
    Inventors: Dawid J. DUVENHAGE, Belma Demirel
  • Patent number: 9018128
    Abstract: A catalyst support solution for improving the attrition resistance of a Fischer-Tropsch catalyst, the solution comprising: crystalline silica and at least one chemical promoter selected from alkali metal bases, wherein the support solution has a pH of greater than or equal to about 7. A structurally promoted catalyst comprising: crystalline silica; at least one basic chemical promoter; and iron; wherein the catalyst comprises SiO2:Fe in a ratio of from about 2:100 to about 24:100. A method of producing a structurally promoted precipitated iron catalyst, the method comprising: forming the structural support solution described above; stirring the support solution for a time to dissolve the silica in the solution; adding the support solution to a precipitated iron catalyst slurry to form an attrition resistant catalyst slurry; and drying the attrition resistant catalyst slurry to yield the structurally promoted precipitated iron catalyst.
    Type: Grant
    Filed: September 10, 2008
    Date of Patent: April 28, 2015
    Assignee: Res USA LLC
    Inventors: Dawid J. Duvenhage, Belma Demirel
  • Patent number: 8946114
    Abstract: A method of producing stable ferrous nitrate solution by dissolving iron in nitric acid to form a ferrous nitrate solution and maintaining the solution at a first temperature for a first time period, whereby the Fe(II) content of the ferrous nitrate solution changes by less than about 2% over a second time period. A method of producing stable Fe(II)/Fe(III) nitrate solution comprising ferrous nitrate and ferric nitrate and having a desired ratio of ferrous iron to ferric iron, including obtaining a stable ferrous nitrate solution; dissolving iron in nitric acid to form a ferric nitrate solution; maintaining the ferric nitrate solution at a second temperature for a third time period; and combining amounts of stable ferrous nitrate solution and ferric nitrate solution to produce the stable Fe(II)/Fe(III) nitrate solution. A method of preparing an iron catalyst is also described.
    Type: Grant
    Filed: May 29, 2009
    Date of Patent: February 3, 2015
    Assignee: Res USA, LLC.
    Inventors: Pandurang V. Nikrad, Jesse W. Taylor, Richard A. Bley, Danny M. Dubuisson, Sara L. Rolfe, Belma Demirel, Dawid J. Duvenhage, Harold A. Wright
  • Patent number: 8946108
    Abstract: A structurally promoted, precipitated, Fischer-Tropsch catalyst that exhibits an RCAI-10 of 0-2.8 and/or produces less than 6 wt % fines after 5 hours ASTM Air Jet Attrition testing, due to formation via: preparing a nitrate solution by forming at least one metal slurry and combining the at least one metal slurry with a nitric acid solution; combining the nitrate solution with a basic solution to form a precipitate; structurally promoting the precipitate with at least one source of silicon to form a promoted mixture, wherein promoting comprises combining the precipitate with (a) silicic acid and one or more component selected from the group consisting of non-crystalline silicas, crystalline silicas, and sources of kaolin or (b) a component selected from the group consisting of non-crystalline silicas and sources of kaolin, in the absence of silicic acid; and spray drying the promoted mixture to produce catalyst having a desired particle size.
    Type: Grant
    Filed: June 2, 2014
    Date of Patent: February 3, 2015
    Assignee: RES USA, LLC.
    Inventors: Dawid J. Duvenhage, Belma Demirel
  • Publication number: 20150023842
    Abstract: A method of preparing a spray dried catalyst by combining spray dried catalyst particles with wax so the spray dried catalyst particles are coated with wax, yielding wax coated catalyst particles, and shaping the wax coated catalyst to provide shaped wax coated catalyst. A method of activating Fischer-Tropsch catalyst particles containing oxides by contacting the catalyst particles with a reducing gas in an activation vessel to produce an activated catalyst, wherein contacting is performed in the absence of a liquid medium under activation conditions. A system for activating a Fischer-Tropsch catalyst containing an activation reactor configured to introduce an activation gas to a fixed or fluidized bed of the Fischer-Tropsch catalyst in the absence of a liquid medium and at least one separation device configured to separate a gas stream comprising entrained catalyst fines having an average particle size below a desired cutoff size from the activation reactor.
    Type: Application
    Filed: August 25, 2014
    Publication date: January 22, 2015
    Inventors: Harold A. WRIGHT, Belma Demirel, Sergio Mohedas, Bahman Rejai, Ray J. Huang, Deena Ferdous, Jesse W. Taylor, Dawid J. Duvenhage, Sara L. Rolfe
  • Publication number: 20140274666
    Abstract: A structurally promoted, precipitated, Fischer-Tropsch catalyst that exhibits an RCAI-10 of 0-2.8 and/or produces less than 6 wt % fines after 5 hours ASTM Air Jet Attrition testing, due to formation via: preparing a nitrate solution by forming at least one metal slurry and combining the at least one metal slurry with a nitric acid solution; combining the nitrate solution with a basic solution to form a precipitate; structurally promoting the precipitate with at least one source of silicon to form a promoted mixture, wherein promoting comprises combining the precipitate with (a) silicic acid and one or more component selected from the group consisting of non-crystalline silicas, crystalline silicas, and sources of kaolin or (b) a component selected from the group consisting of non-crystalline silicas and sources of kaolin, in the absence of silicic acid; and spray drying the promoted mixture to produce catalyst having a desired particle size.
    Type: Application
    Filed: June 2, 2014
    Publication date: September 18, 2014
    Applicant: RENTECH, INC.
    Inventors: Dawid J. DUVENHAGE, Belma DEMIREL
  • Patent number: 8791041
    Abstract: A method of producing a Fischer-Tropsch catalyst by preparing a nitrate solution, wherein preparing comprises forming at least one metal slurry and combining the at least one metal slurry with a nitric acid solution; combining the nitrate solution with a basic solution to form a precipitate; promoting the precipitate to form a promoted mixture, wherein promoting comprises combining the precipitate with (a) silicic acid and one or more selected from the group consisting of non-crystalline silicas, crystalline silicas, and sources of kaolin or (b) at least one selected from non-crystalline silicas and sources of kaolin, in the absence of silicic acid; and spray drying the promoted mixture to produce catalyst having a desired particle size. Catalyst produced by the disclosed method is also described.
    Type: Grant
    Filed: May 28, 2010
    Date of Patent: July 29, 2014
    Assignee: RENTECH, Inc.
    Inventors: Dawid J. Duvenhage, Belma Demirel
  • Publication number: 20130296448
    Abstract: A method of preparing a spray dried catalyst by combining spray dried catalyst particles with wax so the spray dried catalyst particles are coated with wax, yielding wax coated catalyst particles, and shaping the wax coated catalyst to provide shaped wax coated catalyst. A method of activating Fischer-Tropsch catalyst particles containing oxides by contacting the catalyst particles with a reducing gas in an activation vessel to produce an activated catalyst, wherein contacting is performed in the absence of a liquid medium under activation conditions. A system for activating a Fischer-Tropsch catalyst containing an activation reactor configured to introduce an activation gas to a fixed or fluidized bed of the Fischer-Tropsch catalyst in the absence of a liquid medium and at least one separation device configured to separate a gas stream comprising entrained catalyst fines having an average particle size below a desired cutoff size from the activation reactor.
    Type: Application
    Filed: July 2, 2013
    Publication date: November 7, 2013
    Inventors: Harold A. Wright, Belma Demirel, Sergio Mohedas, Bahman Rejai, Ray J. Huang, Deena Ferdous, Jesse W. Taylor, Dawid J. Duvenhage, Sara L. Rolfe
  • Patent number: 8530366
    Abstract: A method of preparing a spray dried catalyst by combining spray dried catalyst particles with wax so the spray dried catalyst particles are coated with wax, yielding wax coated catalyst particles, and shaping the wax coated catalyst to provide shaped wax coated catalyst. A method of activating Fischer-Tropsch catalyst particles containing oxides by contacting the catalyst particles with a reducing gas in an activation vessel to produce an activated catalyst, wherein contacting is performed in the absence of a liquid medium under activation conditions. A system for activating a Fischer-Tropsch catalyst containing an activation reactor configured to introduce an activation gas to a fixed or fluidized bed of the Fischer-Tropsch catalyst in the absence of a liquid medium and at least one separation device configured to separate a gas stream comprising entrained catalyst fines having an average particle size below a desired cutoff size from the activation reactor.
    Type: Grant
    Filed: January 5, 2011
    Date of Patent: September 10, 2013
    Assignee: Rentech, Inc.
    Inventors: Harold A. Wright, Belma Demirel, Sergio Mohedas, Bahman Rejai, Ray Huang, Deena Ferdous, Jesse W. Taylor, Dawid J. Duvenhage, Sara L. Rolfe
  • Patent number: 8138115
    Abstract: A method of producing an iron catalyst for catalyzing the hydrogenation of carbon monoxide is disclosed. The method comprises using a reduced amount of acid for iron dissolution compared to certain previous methods. The resulting acidic iron mixture is heated without boiling to obtain a nitrate solution having a Fe2+:Fe3+ ratio in the range of about 0.01%:99.99% to about 100%:0% (wt:wt). Iron phases are precipitated at a lower temperature compared to certain previous methods. The recovered catalyst precursor is dried and sized to form particles having a size distribution between 10 microns and 100 microns. In embodiments, the Fe2+:Fe3+ ratio in the nitric acid solution may be in the range of from about 3%:97% to about 30%:70% (wt:wt) and the calcined catalyst may comprise a maghemite:hematite ratio of about 1%:99% to about 70%:30%.
    Type: Grant
    Filed: February 26, 2010
    Date of Patent: March 20, 2012
    Assignee: Rentech, Inc.
    Inventors: Belma Demirel, Charles B. Benham, Jesse W. Taylor, Pandurang V. Nikrad, Sara L. Rolfe, Olga P. Ionkina, Dawid J. Duvenhage, Harold A. Wright
  • Publication number: 20110313061
    Abstract: A method of preparing a spray dried catalyst by combining spray dried catalyst particles with wax so the spray dried catalyst particles are coated with wax, yielding wax coated catalyst particles, and shaping the wax coated catalyst to provide shaped wax coated catalyst. A method of activating Fischer-Tropsch catalyst particles containing oxides by contacting the catalyst particles with a reducing gas in an activation vessel to produce an activated catalyst, wherein contacting is performed in the absence of a liquid medium under activation conditions. A system for activating a Fischer-Tropsch catalyst containing an activation reactor configured to introduce an activation gas to a fixed or fluidized bed of the Fischer-Tropsch catalyst in the absence of a liquid medium and at least one separation device configured to separate a gas stream comprising entrained catalyst fines having an average particle size below a desired cutoff size from the activation reactor.
    Type: Application
    Filed: January 5, 2011
    Publication date: December 22, 2011
    Applicant: RENTECH, INC.
    Inventors: Harold A. Wright, Belma Demirel, Sergio Mohedas, Bahman Rejai, Ray Huang, Deena Ferdous, Jesse W. Taylor, Dawid J. Duvenhage, Sara L. Rolfe
  • Patent number: 7968611
    Abstract: A method of producing an iron catalyst for catalyzing the hydrogenation of carbon monoxide is disclosed. The method comprises using a reduced amount of acid for iron dissolution compared to certain previous methods. The resulting acidic iron mixture is heated without boiling to obtain a nitrate solution having a Fe2+:Fe3+ ratio in the range of about 0.01%: 99.99% to about 100%:0% (wt:wt). Iron phases are precipitated at a lower temperature compared to certain previous methods. The recovered catalyst precursor is dried and sized to form particles having a size distribution between 10 microns and 100 microns. In embodiments, the Fe2+:Fe3+ ratio in the nitric acid solution may be in the range of from about 3%:97% to about 30%:70% (wt:wt) and the calcined catalyst may comprise a maghemite:hematite ratio of about 1%:99% to about 70%:30%.
    Type: Grant
    Filed: February 26, 2010
    Date of Patent: June 28, 2011
    Assignee: Rentech, Inc.
    Inventors: Belma Demirel, Charles B. Benham, Jesse W. Taylor, Pandurang V. Nikrad, Sara L. Rolfe, Olga P. Ionkina, Dawid J. Duvenhage, Harold A. Wright