T 0105/84 12-03-1987
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A process or generating energy in the form of heat and hydrogen
I. European patent application No. 81 107 580.3, filed on 23 September 1981, claiming the US priority of an earlier application filed on 31 December 1980 and published under number 55330 on 7 July 1982, was refused by a decision of the Examining Division dated 13 December 1983.
II. The decision was based on the grounds that the subject-matter of Claim 1 could not be regarded as inventive with respect to the teaching of US-A-2 623 812 (1).
The application contained five claims, of which Claim 1 reads as follows:
"A process for the generation of energy in the form of heat and hydrogen comprising reacting in an oxidation type of reaction (12) a source of solid state material (10) and any oxygen supplying reagent (11) composed of at least oxygen and hydrogen, in the presence of an agent (13) promoting the oxidation reaction, producing thereby hydrogen gas (16), heat (15), and an oxide (17) of said solid state material as reaction products, characterised in that said agent (13) promotes the oxidation reaction by inhibiting formation of a passivating oxide on said solid state material during said oxidation reaction, and said agent is recovered (14) and recycled in the process, and said oxide reaction product is subjected to a reduction type of reaction (18) so that said solid state material (10) is also recovered and recycled in the process".
It was further specified in the decision that the subject-matter of Claims 2 to 5 could not be regarded as inventive in view of the teaching of (1), SU-A-125549 (3) and DE-C-45824 (4).
III. In the decision it was stated that document (1) describes a process for the generation of energy in the form of heat and hydrogen which comprises reacting in an oxidation type of reaction a source of solid state material and an oxygen supplying reagent composed of at least oxygen and hydrogen in the presence of an agent promoting the oxidation reaction producing thereby hydrogen gas, heat and an oxide of the solid state material as reaction products. Reference was made in particular to magnesium and aluminium as solid state material, to water as oxygen supplying reagent and to combinations of magnesium or aluminium with mercury and iron as agents promoting the oxidation reaction. It was further specified that the utilisation of mixtures of magnesium and iron or heavily oxidized iron promoted the oxidation reaction by inhibiting the formation of passivating oxide.
With regard to this teaching the claimed process differed only by the recovering and recycling of both the agent promoting the oxidation reaction and the oxide reaction product, the latter being subjected to a reduction reaction before being recycled. These features could not be regarded as inventive since it was common practice to recover and recycle a reaction product whenever this was suitable and of any economic value for the process, as suggested on page 2, lines 5 to 11 in the description of the application itself where it is referred to the article "Thermochemical Hydrogen Generation" by R.H WENTORF and R.E. HANNEMAN published in Science Magazine, 26 July 1974, volume 185, pages 311 to 319 (document (5)). Besides, this combination of features did not lead to any unexpected effect, the possible advantage being actually predictable.
IV. On 8 February 1984 the Appellants filed a notice of appeal against the decision to refuse the application and paid the fee for appeal.
On 11 April 1984 the Appellants filed a statement of grounds of appeal, declaring their readiness (point 13), should Claim 1 not be acceptable, to amend it to the preferred embodiments by incorporation of one or more dependent claims and/or technical features considered essential.
V. In a communication the Board first noted that the state of the art according to the preamble of Claim 1 on file, i.e. generation of energy and hydrogen from the reaction between a source of solid state material and water in the presence of an agent promoting the oxidation reaction and inhibiting formation of a passivating oxide on said solid state material, was illustrated not only in document (1), but even more clearly in US-A-3 540 854 (2).
Since the advantages of the closed-cycle processes in terms of cost and efficiency were generally known from document (5), the subject-matter of Claim 1 was nothing more than an obvious combination of teachings for which no inventive step could be acknowledged.
However, the Board regarded the use of gallium or of gallium-indium alloy as agent promoting the oxidation reaction and inhibiting formation of a passivating oxide on the solid state material as an inventive feature and therefore invited the Appellants to file a new Claim 1 which would incorporate this feature.
VI. In their reply, besides arguments dealing with the relevance of document (5), the Appellants filed a new set of claims entirely different from the Board's suggestions and requested oral proceedings, should rejection of these claims be envisaged.
VII. The essence of the arguments submitted in the Statement of Grounds of Appeal, in the reply and during the oral proceedings held on 12 March 1987 can be summarized as follows:
(i) Document (5) does not provide a solution to the problems of thermochemical hydrogen generation, but rather provides the skilled man with points worthy of consideration to assist in his search for a viable process, such as compatibility, availability and cost of materials, reaction kinetics, separation techniques and heat exchanger systems as well as ecological or safety constraints.
(ii) Document (5) should in any case be considered as the starting point for assessing inventive step, not document (2).
(iii) Document (5) makes no mention of use of an agent which promotes the oxidation reaction by inhibiting formation of a passivating oxide on the solid state material during the oxidation reaction; more specifically, document (5) does not teach the use of aluminium, magnesium, gallium or gallium-indium alloy in closed-cycle processes.
(iv) Whatever the compounds involved in the closed-cycle processes envisaged in document (5), practical considerations indicate that the number of reaction steps will be at least three, whereas the process claimed utilises only two steps.
(v) Document (1) describes the mechanism of alloying aluminium or magnesium with mercury as inhibiting formation of a polarizing hydrogen film whereas the mechanism in the present application involves inhibiting formation of a passivating oxide film by dissolving aluminium or magnesium. Because of this difference document (1) is irrelevant to the process claimed.
VIII. About two weeks before the oral proceedings the Appellants submitted as an auxiliary request a set of 4 claims, of which Claim 1 was modified during the oral proceedings and reads as follows:
"A process for the generation of energy in the form of heat and hydrogen comprising reacting in an oxidation type of reaction (12) aluminium or magnesium (10) and water (11) without application of significant external heat, in the presence of an agent inhibiting the formation of a passivating oxide producing thereby hydrogen gas (16), heat (15), and oxide (17) of aluminium or magnesium as reaction products, characterised in that gallium or gallium-indium alloy (13) is used as an agent inhibiting formation of a passivating oxide on the aluminium or magnesium during said oxidation reaction, and is recovered (14) and recycled in the process, and said oxide reaction product is subjected to a reduction type of reaction (18) so that aluminium or magnesium (10) is also recovered and recycled in the process."
IX. The Appellants requested that the decision under appeal be set aside and the grant of a European patent on the basis of the documents filed during oral proceedings.
1. The appeal complies with Articles 106 to 108 and Rule 64 EPC and is, therefore, admissible.
2. There are no formal objections to the present wording of Claim 1 since all the amendments are adequately supported by the application as originally filed (see Claims 1 to 4).
The restrictive condition that the process has to be carried out without application of significant external heat is disclosed on page 5, third paragraph, lines 9 and 10.
The features identified by numbers 10 to 18 are represented on Figure 1/1 and further specified on page 5, paragraphs 3 and 5.
3. The application relates to a process for generating energy in the form of heat and hydrogen which is carried out without application of significant external heat and enables the recovery of initial reactants in substantially quantitative amounts.
The closest state of the art is represented by document (2) which describes a reactor for producing steam and hydrogen from the reaction between water and amalgamated metal plates submerged therein (abstract of the disclosure). According to the preferred embodiment aluminium plates are amalgamated with a small amount of mercury; this amalgam tends to prevent the formation of a tightly bonded oxide coating that would normally stop or slow down the oxidation reaction. This highly exothermic reaction leads to the formation of solid particles of aluminium oxide and hydroxide which fall off in the water forming a slurry; means are provided both to remove the slurry from the container and to maintain water at a predetermined level, so that a substantially constant output flow of hydrogen and steam can be achieved (column 1, lines 39 to 56; column 2, lines 70 to 72; column 3, lines 1 to 8).
The major shortcoming of this prior art process is its limited efficiency due to the fact that the reaction products are unused, whether they are eliminated or not.
Besides this merely energetic consideration the process described in document (2) involves the use of mercury which is a particularly undesirable and objectionable element for environmental reasons and is obviously lost.
4. In the light of the closest prior art the technical problem underlying the present application has to be seen in improving the thermal efficiency of systems generating energy in the form of heat and hydrogen from the reaction of aluminium or magnesium with water.
This problem is solved according to the application by the combination of features expressed in the characterizing part of Claim 1 which comprise
(i) using gallium or gallium-indium alloy as an agent inhibiting formation of a passivating oxide,
(ii) recovering and recycling this agent,
(iii) reducing the oxide reaction product to the original metal, recovering and recycling this metal.
In view of the results obtained in the Example of the application the Board is satisfied that this technical problem has been plausibly solved.
5. None of the documents on file discloses a process having all the features of Claim 1, and the subject-matter of the application is thus novel. As the Examining Division has not raised the issue of novelty, it is not necessary to consider the matter in detail.
6. For purposes of inventive step the question to be examined is whether the claimed solution would in the light of the other documents have been obvious to a person skilled in the art attempting to solve the problem defined above on the basis of document (2).
6.1. Document (5) presents a general survey of closed-cycle thermochemical processes for generating hydrogen, emphasizing the increasing interest of such processes with regard to open-cycle processes (page 311, column 3, paragraph 3 to page 312, column 1, paragraph 1). Practical considerations indicate that suitable closed-cycle thermochemical processes require water and heat as input ingredients (page 312, column 1, paragraph 2) and comprise at least three reaction steps (page 313, column 1, paragraph 1). As rightly pointed out by the Appellants, these conditions of heat input and number of steps would not suggest a closed cycle based on the oxidation of aluminium or magnesium.
Cost and efficiency considerations, however, would lead the skilled man to the opposite conclusion. Once the general advantages of closed-cycle processes are known, it seems normal to apply this principle to all reactions which yield hydrogen from readily available material and then try to fit them together in some way so that no by-products are left over (page 313, column 3, paragraph 2). In this regard the regeneration of aluminium from alumina certainly does not involve any inventive step since the production of aluminium itself is based on this reaction.
6.2. The ability of gallium to form alloys or solid solutions with aluminium is well known in the art (Kirk-Othmer Encyclopedia, third edition, Volume 11, pages 605 and 611). However, that gallium alloys inhibit the formation of an aluminium oxide or magnesium oxide is not to be found in the documents of the search report and the Board is not aware of this particular property on which the process presently claimed is based. Gallium cannot thus be regarded as an alternative to mercury as taught in document (2), where this element acts as an inhibitor against formation of a passivating layer on aluminium or magnesium. Even the teaching of document (3) does not suggest the subject-matter of Claim 1. According to this disclosure hydrochloric acid is reacted with aluminium amalgamated with a small amount of gallium which results in an increased reaction speed (paragraphs 2 and 5). This kinetic effect cannot be associated with the inhibition of formation of a passivating oxide on aluminium caused by the presence of gallium as required in the present application, since the mere presence of the acid provides the inhibition of a protective oxide layer on the metal. Consequently the use of gallium or gallium-indium alloy in connection with the recovery and recycling thereof have to be regarded as inventive features.
7. Claims 2 to 4 concern particular embodiments of the subject-matter of Claim 1 and are thus supported by the patentability of this claim.
ORDER
For these reasons, it is decided that:
1. The impugned decision is set aside.
2. The case is remitted to the first instance to grant a patent on the basis of the following documents:
- Claims 1 to 4
- Description and
- Figure as submitted during oral proceedings on 12 March 1987.