T 0472/14 21-03-2017

Reasons for the Decision

Granted patent - Sufficiency of disclosure

1. The objections of lack of sufficiency of disclosure raised by the respondent are directed to granted claims 1 and 2.

2. In order to meet the requirements of sufficient disclosure, an invention has to be disclosed in a manner sufficiently clear and complete for it to be carried out by the skilled person, without undue burden, on the basis of the information provided in the patent specification, if needed in combination with the skilled person's common general knowledge. This means in the present case that the skilled person should be in particular able to carry out the process for preparing a supported chromium-based catalyst according to claims 1 and 2.

2.1 In that respect, the only point in dispute between the parties is whether or not the method of determination of the specific surface area mentioned in granted claims 1 and 2 is sufficiently disclosed.

2.2 The respondent argued that the patent in suit did not disclose any details for the method of determination of the specific surface area specified in claim 1 and, considering that BET methods were not sufficiently accurate and that different standard methods would lead to different results, one did not know the boundaries of the claims, which amounted to a lack of sufficient disclosure.

2.2.1 Although there are no specific details of the determination method of the specific surface area mentioned in claim 1, it is indicated in paragraph 23 of the patent in suit that it is measured "by N2 adsorption using the well-known BET technique". It was not contested by the respondent that the BET technique is a usual method for determining the specific surface area, as confirmed by E2, E3 and E8 (page 34, first sentence of section 2).

2.2.2 The respondent argued that the reproducibility of the BET method according to E2 was so poor that it amounted to a lack of sufficiency.

However, it may be seen from the reproducibility values indicated in the Table on page 5 of E2 that the lowest reproducibility (95% reproducibility interval of 23%) is achieved for the sample with the smallest specific surface area (10.7 m**(2)/g), whereby said value is significantly lower than the one specified in granted claim 1 for the support (250 to 400 m**(2)/g). Those data further show that the reproducibility increases with increasing specific surface area to reach a 95% reproducibility interval of 4.1% for a sample having a specific surface area of 289 m**(2)/g i.e. in the range according to granted claim 1. In the Board's view, the fact that those reproducibility data are disclosed in an accepted international standard method (ASTM) for determining the surface area of catalysts and catalyst carriers shows that such a variability is acceptable by the skilled person working in that technical field. Besides, in the range of specific surface area which is relevant for the subject-matter of granted claim 1, the 95% reproducibility interval is of 4.1%, which in relation to an experimental method is not held to constitute an inacceptable lack of accuracy as argued by the respondent. In particular it cannot be considered that the accuracy of the determination method leads to an ambiguity in terms of specific surface area which is such as to amount to a lack of sufficiency.

2.2.3 The respondent argued that the patent in suit also lacked sufficiency because it failed to disclose any details for the method of determination of the specific surface area specified in claim 1 and E4 showed that different standard methods such as E2 and E3 led to different results.

a) Although E2 and E3 are two different ASTM standards for determining the specific surface area of catalysts and catalyst carriers (see titles), it is explicitly indicated in E3 that the multiple point BET method according to E2 is preferred to the single point determination method of E3 because the latter is based on an approximation of the BET equation. It is also indicated that the method of E3 is to be used when rapid specific surface area determinations are desired (sections 1.1, 1.2 and 11.1 of E3).

That statement is confirmed by the data related to the precision of the methods indicated in section 12.2 of E2 and section 13 of E3, which show that the most accurate method is the one of E2.

Therefore, on the basis of that information, the skilled person desiring to measure accurately the specific surface area of a support by the BET technique specified in paragraph 23 of the patent in suit, would consider E2 and not E3. Also, in view of the above, it is not surprising that it was found in E4 that the methods of E2 (based on a BET method) and E3 (based on an approximation of a BET method) led to somewhat different results. In that respect, it may be seen from the comparison of the data of the three materials studied in E4 that the difference in surface area is of maximum 5.5 % for materials having a surface area of 10.9, 158 and 291 m**(2)/g (according to E2). Therefore, the variability between E2 and E3 is, in the Board's view, not so large that the skilled person would conclude that the methods of E2 and E3 lead to significantly different results.

b) Regarding the sample pretreatment of the materials to be tested, it is correct that it is indicated in E4 (pages 1 and 2: paragraphs starting with "Caution:") that the sample pretreatment is critical and that the indications given therefor in E2 and E3 must be followed.

In that respect it is indicated both in E2 (section 7.8) and E3 (sections 9.6 and 9.7) that the pretreatment should be carried out at 300 °C. Although it may be derived from "Note 3" of E2 (page 3, between sections 7.9 and 7.10) and "Note 2" of E3 (page 3, between sections 9.6 and 9.7) that lower temperatures may be used for materials which decompose at 300°C, the general teaching of E2 and E3 is that the pretreatment is usually carried out at 300°C. In that respect, the indication at section 11.2 of E2 that the pretreatment temperature should be indicated is understood as being relevant when the operator deviates from the usual temperature of 300°C. That conclusion is confirmed by the indication in E4 that a temperature of 300°C was used as taught in E2 and E3 (pages 1 and 2: paragraphs starting with "Caution:").

Therefore, when carrying out a specific surface area determination by BET technique according to either E2 or E3, the skilled person would perform a degassing (pretreatment) at 300 °C. For those reasons it cannot be concluded that it was shown that the sample pretreatment used in E2 and E3 is related to an issue of insufficiency of disclosure, as argued by the respondent.

2.2.4 In view of the above the respondent's objection based on E2 to E4 is not persuasive.

2.2.5 The respondent further argued that the skilled person could contemplate using different BET methods than the one of either E2 or E3 to determine the specific surface area of a support, e.g. E11 or E12 and that it was to be expected that different methods led to different results.

However, there is no evidence on file that any of those other methods than E2/E3, in particular E11 or E12, effectively leads to significantly different results than E2.

In that respect, the respondent's argumentation according to which the method of E11 required a sample pretreatment at only 160°C (as compared to 300°C in e.g. E2) was not contested by the appellant. However, there is, also in that regard, no evidence on file that the method of E11 effectively leads to different results in terms of specific surface area as compared to e.g. E2. There is also no evidence that the ambiguity in the determination method would be so severe that the skilled person would not be in a position to carry out the process according to granted claim 1.

Therefore, that objection, which is not supported by facts, cannot be adhered to.

2.2.6 The respondent's objections addressed in above sections 2.2.2, 2.2.3 and 2.2.5 are all related to the issue whether the skilled person is in a position to determine unambiguously if he is working within or outside the scope of the claims. The question whether or not that issue effectively amounts to a lack of sufficiency or if it is an issue of clarity was the object of many decisions as indicated in Case Law of the Boards of Appeal of the EPO, 8th edition, 2016, II.C.4.5, 5.6.5, 5.6.8 and 7.2, some of which have been relied upon by the parties during the oral proceedings before the Board. As indicated therein, an ambiguity of a parameter in the claims is not enough in itself to deny sufficiency of disclosure and the question whether said ambiguity leads to insufficiency of disclosure is to be decided on a case-by-case basis (see e.g. reference to T 2403/11 and T 608/07 on pages 338 and 359 in the Case Law, supra). Rather, with respect to sufficiency the relevant question is whether the patent in suit provides sufficient information which enables the skilled person when taking into account common general knowledge to reproduce the invention (see e.g. reference to T 466/05 on page 359 in the Case Law, supra).

In the present case, it is concluded in view of the considerations given in above sections 2.2.2 and 2.2.3 that it was not shown that the skilled person would have any difficulty to identify silica-based supports having a suitable specific surface area in order to carry out the process of granted claim 1, whereby said specific surface area is determined according to any suitable BET method known in the art. Therefore the alleged ambiguity relied upon by the respondent was, in the present case, not shown to amount to a lack of sufficiency of disclosure. Rather, that issue could at most be related to a matter of clarity pursuant to Article 84 EPC, which however cannot be addressed at the present stage of the proceedings since the parameter in question is already present in the granted claims (see G 3/14, OJ EPO 2015, A102: catchword).

2.3 The question whether or not "the claimed benefits of the surface area and Cr/Ti loadings can be obtained", which was put forward by the respondent, is at most related to the question whether a technical effect is present over the whole scope of the claims, which in the absence of any effect mentioned in granted claim 1 is at most an issue of inventive step pursuant to Article 56 EPC rather than an issue of sufficiency of disclosure (G 2/03, OJ EPO 2004, 448: section 2.5.2 of the reasons).

2.4 The respondent also argued that it was not clear from the claims whether the "relevant" surface area was that of the catalyst comprising chromium on silica from step a) of claim 1 or that of the silica support per se.

2.4.1 However, it is derivable from the wording of claim 1 itself that for the ratios specified in claim 1 use is made of the specific surface area of the support per se (i.e. without chromium and/or titanium: see wording of granted claim 1 "specific surface area of the support"). That reading of claim 1 is further supported by the patent specification (see e.g. paragraphs 22, 23, 28, 33 and 58). It is further clear from paragraph 58 in combination with column 9 of Table 4 of the patent in suit that the expression "Surface area starting catalyst" indicated in each of Tables 1-4 of the patent in suit is related to the specific surface area of the neat silica support, not the chromium containing support obtained after step a) of claim 1.

2.4.2 The fact that step b) of claim 1 is a dehydrating step is not incompatible with that reading. In particular, there is no reason to consider that the specific surface area measurement should be made in the presence of water. In that respect, it is in particular derivable from paragraph 53 of the patent in suit that the deposition of chromium requires wetness impregnation and thus calls for a subsequent dehydrating step b).

2.4.3 Therefore, that argument is not persuasive.

2.5 The respondent's objection raised against granted claim 2 is based on the same arguments as those identified above in respect of granted claim 1. They are, for the same reasons, not convincing.

3. For those reasons, the respondent's objections pursuant to Article 100(b) EPC are rejected.

4. Remittal

The issues of novelty and inventive step were not addressed in the contested decision. Further considering that the appellant requested remittal to the first instance, which was not objected to by the respondent, it is appropriate to remit the case to the department of first instance for further prosecution (Article 111(1) EPC).