User:Rabot

United States Patent 4,424,275

Logistics

• Patent 4,424,275
• Continuous Process for Producing N-Butanol Employing Anaerobic Fermentation
  • Issued: Jan. 3, 1984 (Filed: Aug. 3, 1981)
• Inventor: Sidney Levy

The Invention

From its inception, the fermentation of n-butanol from carbohydrate-containing substrate was hampered by several problems, the largest of which was the maximum n-butanol concentration of 2.5% in the fermentation broth, at which point it became toxic to the butanol-producing bacteria. The aims of this invention were to address these shortcomings in the old batch-reactor processes as well as introduce a continuous process for the production of solvents by anaerobic (oxygen-free) fermentation of substrates that contained sugars. The invention is both a process that allows for the continuous production of solvents and their extraction as well as an apparatus for conducting this process. It allows for the continuous production of n-butanol using various substrates and extraction solvents while achieving higher n-butanol concentrations and reusing the extraction solvents.

I found this patent interesting because butanol has many advantages over ethanol as an alternative, biologically-based fuel source and because I have worked in refining. It will be interesting to explore other inventions, including bacteria cultures and devices, and to see how this technology is being employed in several pilot plants. I found the patent while searching Google Patents: [1]. Google Patents includes the patent overview and documentation: [2]. The drawings are particularly interesting: [3].

Rabot 23:23, 23 January 2011 (EST)

Patentability Case-Study: Tracing Hotchkiss, A&P, and Lyon

Cited Patents

• Patent 2,389,263
• Method of Producing 2:3 Butanol
• Patented Nov. 20, 1945
• Alfred J. Liebmann and George de Becze
  • Assignors to Schenley Distillers Corporation, NY

• Patent 1,875,536
• Continuous Butyl Alcohol Fermentation Process
• Patented Sept. 6, 1932
• Maynard C. Wheeler and Charles D. Goodale
  • Assignors to Commercial Solvents Corporation, IN

Disclosure

Sidney Levy’s 1984 patent (described above) cites the 1932 patent of M. C. Wheeler et al, “Continuous Butyl Alcohol Fermentation Process,” and the 1945 patent of A. J. Liebmann et al, “Method of Producing 2:3-Butanediol.” For the purposes of this analysis, I will assume that the Wheeler patent would not have interfered with the Liebmann patent given the analyses of Hotchkiss and A&P, even if this is not the case. All three patents claim processes for fermentation and extraction of a desired substance from a fermentation brew. In the Liebmann patent, the aim is to produce a “substantially pure 2:3 butylene glycol (Col. 1, lines 2-3) while greatly reducing “the cost of extraction of the butylenes glycol from a fermented beer which contains said glycol” (Col. 1, lines 13-16). The Wheeler patent is much closer to the claims of Levy’s patent. Like Levy, Wheeler et al disclose a “continuous process for the fermentation of carbohydrate-containing mashes by means of butyl alcohol producing bacteria” (lines 1-4). It also treats the producing of n-butyl alcohol and other common products through micro-organisms such as Clostridium acetobutylicum; this is also similar to the Levy patent. Both Wheeler et al and Levy hope to address common shortcomings in old batch-reactor processes while also claiming a continuous process for the production of solvents by fermentation of carbohydrate substrates. Liebmann et al claim a fermentation and extraction, but their patent pertains to a different product with very different properties and produced by an organism that behaves differently. Furthermore, it claims both batch and continuous processes where Levy and Wheeler et al’s patents both pertain to continuous processes exclusively. All three patents claim both a process that allows for the continuous production of solvents and their extraction as well as an apparatus for conducting this process. Both Wheeler et al and Levy allow for the continuous production of n-butanol using various substrates and extraction solvents while achieving higher n-butanol concentrations and reusing the extraction solvents.

For the criterion of non-obviousness, it is important to note the following aspects of each patent. All patents give general descriptions of which fermentation agents and solvents can be employed in the process at each stage, but they also relate specific constraints and examples of each class. The Levy patent describes a continuous process that involves one tubular reactor, consisting of concentric tubes, and an extraction column. Condensers and feed tanks are employed as needed. One of the concentric tubes of the reactor contains a mesh-like membrane that serves as the substrate for the fermenting bacteria. Liebmann et al disclose a method for fermentation and concentration of a butylene-glycol-containing beer, then the recovery, extraction, and precipitation of the butylenes-glycol. The process can be conducted continuously, as semi-batch, or batch. The process primarily involves separating the beer into a solvent phase and a semi-sludge phase. Each is then treated with solvents. The emphasis is upon the extraction portion of the process, not the fermentation. Several examples of both batch and continuous processes are given. The device disclosed by Wheeler et al is closer to Levy’s invention. Both start with a coarse carbohydrate meal that is diluted to 8% in water. It is pressure cooked in steam and then cooled to 37○C. The mash is then inoculated with the fermenting culture at 2% by volume. New mash is added at intervals. The device differs primarily in its lack of a culture mesh and in the use of a series of tanks rather than a large plug-flow tank.