Increasing concentrations of carbon dioxide in the atmosphere have stimulated significant global research and development efforts regarding the reduction in emissions from all point and non-point sources. In addition to technologies that do not use carbon feedstocks or which capture and &#x22;permanently&#x22; store carbon dioxide (i.e., sequestration), there is considerable worldwide interest for dissociating waste stream carbon dioxide molecules into their constituent carbon and oxygen atoms (&#x22;CO2 splitting&#x22;) as a final &#x22;end-of-pipe&#x22; treatment option. This document presents a review of on-point issued and applied for patents in the field of carbon dioxide splitting. The findings suggest patents in this area appear to be subject to a higher standard because of the global importance of the carbon dioxide issue. Authorities may be hesitant, on policy grounds, to issue broad-ranging patents for carbon dioxide splitting in order to prevent a worldwide reluctance towards adopting feasible treatment methods because of the high patent licensing costs that may accrue

Sierra Rayne

English

Nature Precedings

  
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Review of the Carbon Dioxide Splitting Patent Literature 
 
Sierra Rayne* 
 
Water Treatment Technology Program, Thompson Rivers University, Box 3010, 900 McGill 
Road, Kamloops, British Columbia, Canada, V2C 5N3 
 
Corresponding author: (e-mail) rayne.sierra@gmail.com or srayne@tru.ca; (phone) +1 (250) 
852-7026. 
 
 
 
Disclaimer: 
This paper is intended for educational purposes only, and cannot and should not be construed in 
any form as offering, or attempting to offer, legal advice or providing guidance in any legal or 
commercial research and development activities. The opinions presented in this paper are not 
legal opinions. Any individual or other entity should not rely on any information or opinions 
presented or implied in this document for legal proceedings of any form, and should instead seek 
and obtain independent legal advice from a qualified professional in the corresponding 
jurisdiction. 
 
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Increasing concentrations of carbon dioxide (CO2) in the atmosphere have stimulated 
significant global research and development efforts regarding the reduction in CO2 emissions 
from all point and non-point sources. In addition to technologies that do not use carbon 
feedstocks or which capture and "permanently" store CO2 (i.e., sequestration), there is 
considerable worldwide interest among the academic, industrial, and government communities 
regarding methods for dissociating waste stream carbon dioxide molecules into their constituent 
carbon and oxygen ("CO2 splitting") atoms as a final "end-of-pipe" treatment option. This 
document presents a review of on-point issued and applied for patents in the field of carbon 
dioxide splitting. 
 
Bockris applied for a US Patent with a priority date of March 22, 2005 entitled “Method and 
Device for Dissociating Carbon Dioxide Molecules.”1 The intent of this invention is to thermal 
catalytically and/or electrochemically split carbon dioxide, and to use electrochemical methods 
to transport oxygen ions across a membrane and create a solid carbon residue inside the reactor. 
While the primary means of splitting CO2 in this application appears to be electrochemical, the 
patent speaks to using elevated temperatures at the membrane interface where CO2 is to be 
adsorbed and subsequently split, and thus also likely appears to contemplate potential thermal 
catalytic processes. 
 
The abstract of this patent reads as follows: 
 
"An apparatus is provided for dissociating carbon and oxygen from carbon dioxide 
molecules. The apparatus includes a thin plate made of a solid permeable ion-conducting 
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membrane having a partial coating of platinum on a first side and ruthenium oxide on a 
second. An electric potential is applied between two surfaces of the membrane and the 
membrane heated by a heating element. Carbon dioxide gas is brought into contact only 
with the negatively charged first side of the membrane. The oxygen atoms are put under 
an electric field, separate from the carbon atoms and enter the membrane, and become 
oxygen ions. The ions are transported across the membrane to the positively charged side, 
where they lose their negative charge and exit the membrane as pure oxygen. The carbon 
does not pass through the membrane and is left behind. The carbon is detached from the 
membrane and collected as powder for use or disposal." 
 
As noted in the patent's Detailed Description (emphasis added), “[t]he present invention … 
overcomes problems with the prior art by efficiently dissociating carbon dioxide molecules 
(CO2) into the environmentally friendly elements of oxygen (O2) and carbon (C). It is well 
known that CO2 is a stable molecule and therefore difficult to dissociate. A thermodynamic 
analysis … of the standard free energy of formation of CO2 from C and O2 shows that the 
formation of CO2 is highly favored and the reverse reaction cannot occur unless forced to do so 
by means of an electrical potential … The present invention utilizes a solid electrolyte, raised to 
a temperature of more than 1000°C, with an applied electric potential.” 
 
Thus, this patent does not address the direct uncatalyzed thermal gas-phase splitting of carbon 
dioxide, but rather considers the coupled thermal and electrochemical splitting of carbon dioxide 
at a solid-gas interface. 
 
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The three broadest claims are claims 1, 11, and 19 (emphases added). 
 
Claim 1 states as follows: 
 
"1. An apparatus for dissociating carbon dioxide molecules, the apparatus comprising: 
 
an ion-conducting oxygen-permeable membrane having a first surface and a second 
surface opposite the first surface; 
 
a power source for applying a first voltage to the first surface and a second voltage, 
which is greater than the first voltage, to the second surface; and 
 
a chamber, mechanically coupled to the first surface, for containing CO2 gas, such that 
the CO2 gas within the chamber contacts the first surface of the membrane such that O 
atoms from the CO2 gas contacting the first surface exit the second surface of the 
membrane." 
 
Claim 11 states as follows: 
 
"11. An apparatus for dissociating carbon dioxide molecules, the apparatus 
comprising: 
 
membrane means for dissociating CO2 gas into C and O atoms, the membrane means 
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including a first surface for contacting the CO2 gas and a second surface through which 
the O atoms exit; and 
 
a power source for applying a first voltage to the first surface and a second voltage, 
which is greater than the first voltage, to the second surface so as to cause the membrane 
means to transport the O atoms from the first surface to the second surface." 
 
Claim 19 states as follows: 
 
19. A method for dissociating carbon dioxide molecules, the method comprising the 
steps of: 
 
"heating an ion-conducting membrane having a first surface and a second surface 
opposite the first surface; 
 
applying a first voltage to the first surface of the ion-conducting membrane; 
 
applying a second voltage, which is greater than the first voltage, to the second surface 
of the ion-conducting membrane; and 
 
contacting carbon dioxide gas with the first surface of the ion-conducting membrane." 
 
This patent application appears to have received an unfavorable review by the International 
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Searching Authority (ISA) acting on behalf of the World Intellectual Property Organization 
(WIPO), which held that while the content was novel and had industrial applicability, all claims 
lack an inventive step as being obvious over previous US patents. 
 
Claims 1, 11, and 19 by Bockris were held obvious as Joshi 2 teaches the following: (a) an 
ion-conducting oxygen-permeable membrane having a first surface and a second surface 
opposite the first surface; (b) a power source for applying a first voltage to the first surface and a 
second voltage, which is greater than the first voltage, to the second surface; and, (c) a chamber, 
mechanically coupled to the first surface, for containing O2 gas, such that the O2 gas within the 
chamber contacts the first surface of the membrane such that O atoms from the O2 gas contacting 
the first surface exit the second surface of the membrane. Joshi’s patent refers to “[a] leak 
detector employing … an oxygen ion-conducting membrane”, demonstrating the breadth of prior 
patent art considered in the obviousness test for Bockris’ application. 
 
While Joshi does not teach an apparatus for dissociating CO2, or that the chamber contains 
CO2, the search authority held that Gomberg 3 does teach dissociating CO2 gas in a chamber 
(albeit using radiolytic methods), and that it would have been obvious to one of ordinary skill in 
the art to combine the teachings of Joshi with those of Gomberg to provide Bokris’ apparatus for 
dissociating CO2 molecules. The remaining more specific dependent claims of Bokris were 
rejected as obvious using similar reasoning. 
 
Claim 23 of Bokris utilized a method of removing solid carbon deposits from the membrane, 
and the search authority held that while neither Gomberg nor Joshi teach on this subject, that 
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Rankin 4 teaches a method of removing carbon deposits from a surface (a coke oven ascension 
pipe), and that it would have been obvious to combine the teachings of Gomberg, Joshi, and 
Rankin to develop a method for dissociating CO2 molecules, separating the oxygen from the 
reactor using an oxygen selective membrane, and collecting and removing the solid carbon 
product from the reactor interior. 
 
The ISA decision on Bokris appears to have set a high obviousness standard for CO2 splitting 
patent applications. While Bokris’ method proposed thermal catalytic and/or electrochemical 
methods to split carbon dioxide, the authority appears to have held that Gomberg’s use of 
radiolytic CO2 dissociation made alternate means of splitting CO2, as in Bokris, obvious. This 
implies that all non-catalytic and catalytic means (e.g., thermal, electrochemical, radiolytic, etc.) 
of splitting CO2 are obvious by way of Gomberg. Gomberg also appears to only contemplate the 
partial dissociation of CO2 to CO and O2 (e.g., CO2 → CO + ½O2), and thus the search authority 
extended their obviousness argument in Bokris to the complete splitting of CO2 to C and O2. 
 
Similarly, the authority held that prior use of oxygen-selective membranes (such as zirconia) 
for leak detectors made the use of these membranes obvious for selectively removing oxygen 
from a CO2 splitting reactor. Finally, the authority also held that prior use of carbon cleaning 
systems in coke oven ascension pipes made obvious the use of carbon collection systems in a 
CO2 splitting reactor. 
 
It is also of note that the search authority did not need to refer to the prior art in the peer-
reviewed literature for their obviousness decision in Bokris. As is discussed in the companion 
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paper to this review, the peer-reviewed literature sets compelling obviousness issues for CO2 
splitting patent applications due to the extensive work conducted in this field over the past 
several decades. 
 
With the decision in Bokris seeming to hold obvious all means of splitting CO2, the recent 
patent application by the Global Research division of General Electric (Ku et al. 5) appears to be 
the test of whether catalytic means of splitting CO2 will be held obvious based on the decision in 
Bokris. In their patent, Ku et al. disclose “a multifunctional catalyst systems comprising a 
substrate; and a catalyst pair disposed upon the substrate; wherein the catalyst pair comprises a 
first catalyst and a second catalyst; and wherein the first catalyst initiates or facilitates the 
reduction of carbon dioxide to carbon monoxide while the second catalyst initiates or facilitates 
the conversion of carbon monoxide to an organic compound.” Claim 1 is the broadest in this 
application, and is equivalent to the disclosure quoted above. 
 
Ku et al. likely contemplates the splitting of CO2 to CO and O2, but the restriction of the 
second catalyst facilitating the conversion of carbon monoxide to an organic compound suggests 
that the splitting of CO to C and O2 may not be contemplated. Organic compounds are generally 
defined as those containing carbon and hydrogen, and may not include solid carbon phases such 
as graphite and amorphous carbon. Reverse water gas shift and Fischer-Tropsch reactions are 
contemplated in the application, further suggesting that the second catalyst is likely not for the 
splitting of CO to C. 
 
While this may appear to be a “loophole” in the Ku et al. application, several mitigating 
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factors warrant caution in this regard. Obviousness issues, technical difficulties, and previous 
peer-reviewed literature may have played a role in restricting the scope of the claims. The 
obviousness issues in Bokris may have been felt by General Electric to apply to all attempts to 
split CO2 to carbon and oxygen, whether they be thermal, radiolytic, electrochemical, or 
catalyzed, or any combination of these. As well, General Electric may have not been able to 
achieve the complete splitting of CO2 to C and O2 using any studied catalyst systems. However, 
as noted above and based on the broad prior art used, the decision in Bokris also appears to 
contemplate as obvious any attempt to split CO2 to C and O2. The decision in Ku et al. will be 
interesting, as it will determine whether the decision in Bokris did indeed contemplate all forms 
of splitting CO2 as obvious by way of Gomberg. 
 
The pending decision on Ku et al. may also depend not only on the prior art in peer-reviewed 
literature and the decision in Bokris, but also on a Canadian patent by Iwanami et al.6 This patent 
teaches, in its broadest claim, “a catalyst for the reduction of carbon dioxide comprising a 
transition metal on zinc oxide alone or on a composite containing zinc oxide and at least one 
metal oxide of a metal selected from the metals in Group IIIb and Group IVa in the Periodic 
Table.” Although the chemical makeup of the catalyst in Iwanami et al. appears specific, in 
concert with the prior art from the peer-reviewed literature, the pending application by Ku et al., 
and the decision in Bokris, catalytic splitting of CO2 appears to be a difficult area with regard to 
obviousness issues. 
 
Given the usual test standards for obviousness, it could reasonably be construed that patents in 
this area are subject to a higher standard because of the global importance of the carbon dioxide 
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issue. Authorities may be hesitant, on policy grounds, to issue broad-ranging patents for CO2 
splitting in order to prevent a worldwide reluctance towards adopting feasible treatment methods 
because of the high patent licensing costs that may accrue. 
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References 
                                                 
1
  Bockris, B. “Method and Device for Dissociating Carbon Dioxide Molecules.” United 
States Patent Application 2006/0213782 A1. Filed March 22, 2005. 
2
  Joshi, A.V. “Leak Detector.” United States Patent 4674321. Filed December 6, 1985. 
3
  Gomberg, H.J., Lewis, J.G., Powers, J.E. “Radiolytic Dissociative Gas Power Conversion 
Cycles.” United States Patent Re. 31697. Reissued October 9, 1984. 
4
  Rankin, R.C. “ Apparatus for cleaning coke oven ascension pipe.” United States Patent 
4039393. Filed July 21, 1976. 
5
  Ku, A.Y.C., Ruud, J.A., Manoharan, M., Kool, L.B., Martins-Loureiro, S.P., Blohm, 
M.L., Norman, B.G. “Reactor for Carbon Dioxide Capture and Conversion.” United 
States Patent Application 2007/0149392 A1. Filed December 22, 2005. 
6
  Iwanami, H., Yoshizawa, T., Suzuki, T. “Catalyst for Reduction of Carbon Dioxide.” 
Canadian Patent 2126502. Filed June 25, 1993. 
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Apparatus for cleaning coke oven ascension pipe.” United States Patent 4039393.

Catalyst for Reduction of Carbon Dioxide.” Canadian Patent 2126502. Filed

Leak Detector.” United States Patent 4674321. Filed

Method and Device for Dissociating Carbon Dioxide Molecules.” United States Patent Application 2006/0213782 A1. Filed

Radiolytic Dissociative Gas Power Conversion Cycles.” United States Patent Re.

Review of the Carbon Dioxide Splitting Patent Literature

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Review of the Carbon Dioxide Splitting Patent Literature

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