T 0493/90 10-12-1991

1. The appeal is admissible.

2. The Appellant has requested that the erroneous values 44.25%, 44.25%, 50.44% and 57.92% in the last column of Table 1 (values of K in examples 3 to 6) be replaced by the correct values 79.37%, 79.37%, 101.79% and 137.67% respectively. In the following, the first table of page 6 of the patent is termed Table 1a and the second one Table 1b.

In order for correction under Rule 88 to be allowable, it must be established (i) that an error is present in the document as filed at the EPO and (ii) that the correction is obvious in the sense set out in Rule 88, i.e. "in the sense that it is immediately evident that nothing else would have been intended than what is offered as the correction".

The values of K are derived from calculations based upon the formula K = 100(X-Y)/Y as indicated in the last column of Table 1a. With regard to examples 1 and 2 the values of K mentioned in the last column are in agreement with the values of X and Y stated in the third and fourth columns of Table 1a when the calculation is based on this formula. However, this is not the case for examples 3 to 6. Therefore by solely checking this simple calculation the skilled reader would recognise that an error has occurred in Table 1a. Having noticed this error he would try to find out whether this inconsistency is due to a calculation error or whether the values of X or of Y themselves are not correct. In the Respondent's opinion a third possible cause for this inconsistency could be that the formula itself is wrong and should read K = 100(X-Y)/X since the values of K given in Table 1a for examples 3 to 6. were obtained by dividing the difference 100(X-Y) by X instead of Y.

As the values of X reported in Table 1a are identical to those given in Table 1b (last column) and in Table 2 (page 7, third column), the skilled reader would have no reason to believe that they are wrong. The value of 22.3 for Y is in agreement with the CuCl2 content and catalyst composition stated at page 5 (lines 49 to 59) of the patent and consequently it can also be regarded as correct. Moreover it is expressly indicated in Claim 1 and in the paragraph bridging pages 4 and 5 of the patent that the molar ratio "outer Me/outer Cu", namely X, is at least 40% higher than the molar ratio Y = Sigma [Me]/[Cu]. As this statement is equivalent to (X-Y)/Y > 40% it is immediately derivable therefore that the formula mentioned in Table 1a is also correct. Consequently only one possibility remains as to the erroneous values in Table 1a, namely the values of K in examples 3 to 6. It is also immediately evident in the present case that nothing else would have been intended than what is offered as the correction since calculation of the values of K on the basis of the formula and values of X and Y indicated in Table 1a leads to 79.37% for examples 3 and 4, 101.79% for example 5 and 137.67% for example 6. For the preceding reasons the Board considers that the request for correction under Rule 88 is allowable and therefore the corrected version of the patent is taken as the basis for the decision of the Board.

Main Request

3. There are no objections under Article 123(2) and (3) to the amended claims. Claim 1 is based upon Claim 1 of the application as originally filed and upon features stated in the description thereof, namely at page 7, lines 18 to 19; page 9, lines 9 to 11; page 12, lines 7 to 22, and page 8, lines 19 to 22. The lower limit "at least 79.37%" is supported by the corrected value of K in Table 1. The Board cannot share the Respondent's opinion that only three values of K are disclosed in the original application since it is expressly mentioned at page 7 (lines 20 to 26) thereof that X may vary between 40:1 and 53:1. The corresponding range for K is directly derivable from Table 1 which indicates these upper and lower values as well as the value of Y. The dependent Claims 2 to 4 and the process Claims 5 to 9 are supported by the original Claims 2, 3 5 and 6 to 10. The activation step in air at 180 to 300°C is clearly disclosed in the original description, at page 8, lines 12, 13, 28 and 29. Therefore these claims are also in conformity with the requirements of Article 123(2).

In addition, the amended claims manifestly do not broaden the scope of the granted claims since the range for the molar ratio outer Me/outer Cu has been restricted.

4. The Board has come to the conclusion that of the new documents cited for the first time at the appeal stage only document (8) was relevant in view of its teaching about the cause of stickiness. Therefore, it has decided to introduce (8) into the proceedings pursuant to Article 114(1) EPC.

5. Concerning novelty the Board cannot follow the Respondent's opinion that document (3) already discloses a catalyst having a molar ratio outer Me/outer Cu, as determined by X-Ray Photoemission Spectroscopy (XPS), which is at least 79.37% higher than the mole ratio Y.

According to the Respondent, the XPS data reported in his letter of 26 February 1991 were measured on catalyst samples which were prepared as set forth in examples 1, 2 and 3 of document (3) and then handled under air or nitrogen before XPS analysis or exposed to oxychlorination conditions for 24 hours. The corresponding XPS data in Tables I, II and III demonstrate that the distribution of copper on the surface of the catalyst as defined by K = 100(X-Y)/Y depends upon the conditions under which the catalysts were handled before analysis. All the samples exhibit values for K which are smaller than the lower limit 79.37% stated in Claim 1 except for example 1 of Table II. However as admitted by the Respondent during oral proceedings, the diluted catalyst of this example was not subjected to a treatment under oxychlorination conditions like the diluted catalyst of (3), although according to (3), this treatment causes the transport of a portion of the CuCl2 from the surface of the supported catalyst to the particles of the bare support (cf. column 3, lines 20 to 28). Instead of this treatment, nitrogen was passed through the mixture for a short time at room temperature. Under these circumstances and as (3) does not disclose any treatment of the catalyst with nitrogen, the Board must conclude that the catalyst of example 1 of Table II does not represent a catalyst according to the teaching of (3). The Respondent's argument that CuCl2 is hygroscopic and formation of the hydrate should be avoided does not prove that the prior art catalysts were handled under nitrogen since handling under dry air would also prevent this formation. Therefore the claimed catalyst is regarded as novel with respect to those of (3) in that the concentration of copper on the surface of the catalyst particles is reduced to a different extent.

6. It still remains to be examined whether the requirement of inventive step is met by the claimed subject-matter.

6.1. In agreement with the parties, the Board considers document (3) as the closest prior art. This document discloses a catalyst for the synthesis of 1,2-dichloro- ethane (DCE) by means of ethylene oxyhydrochlorination within a fluidised bed. This catalyst consists of cupric chloride supported on a fluidisable alumina support, the amount of CuCl2 corresponding to a copper content of 2 to 10. wt%. The catalyst was prepared by impregnation of the support with a solution of CuCl2 (cf. column 1, line 54 to column 2, line 20). According to (3) the catalyst particles have a tendency to agglomerate during operation of the oxyhydrochlorination process and this "stickiness" impairs the fluidisation characteristics of the bed. In order to decrease or inhibit stickiness bare fluidisable alumina support is added to the supported cupric chloride catalyst. As the oxyhydrochlorination proceeds, a portion of the cupric chloride on the supported catalyst becomes released therefrom and is deposited in situ on the bare support so that stickiness of the CuCl2 containing catalyst particles in the fluid bed is alleviated (cf. column 3, line 52 to column 4, line 7, Abstract). In example II no stickiness was observed in a run of 85 hours carried out in a laboratory reactor of 300 mm diameter with a catalyst bed height of 38 cm, and the bed fluidised excellently throughout. The highest DCE yield with respect to ethylene (termed % Efficiency in Table I of (3)) is 95.2% with a HCl/C2H4 feed ratio of 2.12. If HCl is not in excess over the stoichiometric requirement, i.e. with a HCl/C2H4 ratio less than 2, the highest DEC yield obtained with the diluted catalyst of example II is 94.9%.

6.2. In the Board's view, the problem to be solved with respect to this prior art can be seen in providing a catalyst which in industrial exploitation exhibits excellent fluidisation properties and simultaneously leads to high DCE yields and high HCl conversions.

It is proposed to solve this problem by depleting the copper concentration at the surface of the catalyst with respect to the bulk copper concentration in the catalyst to the extent defined in the characterising part of Claim 1. In view of the fluidisation quality, the DCE yields and the HCl conversions achieved with the catalysts of examples 12, 15, 22 and 24 of the patent under conditions used in industrial exploitation, it appears to the Board that this problem has been plausibly solved by the claimed features.

6.3. During oral proceedings the Appellant has contended that the problem to be solved with respect to (3) was to provide a catalyst with improved fluidisation properties which enables to obtain higher DCE yields in industrial exploitation while maintaining high HCl conversions. However the Respondent has submitted that no improvement was obtained with the claimed catalyst.

6.3.1. The Appellant's comparative tests illustrating the performance of the catalysts of (3) and of the disputed patent (cf. Tables C and D of the Statement of Grounds of Appeal and of the letter dated 5 September 1989) were contested by the Respondent, who, for his part, also performed tests with the catalysts of (3) (cf. Table B, examples 1 to 66 of the letter dated 16 February 1990). However, according to the Respondent's tests, the catalysts of (3) containing 5% copper would exhibit excellent fluidisation properties before dilution with the bare alumina whatever the reactor design. This is not consistent with the stickiness rating of 3.5 or 3.75 given in example II of document (3) (a patent assigned to the Respondent). On the other hand, the Appellant's Tables C and D show that addition of the bare alumina to the supported cupric chloride catalyst would not improve fludisation at all contrary to the teaching of (3) and would lead to DCE yield which are very low in comparison with those stated in Table I for a contact time of about 20. seconds. In view of these discrepancies, the Board doubts that the prior art catalyst has been prepared following the teaching of (3) and, thus, it is not convinced that the alleged improvements have been really achieved.

6.3.2. A direct comparison of the DCE yields indicated in Table 2 of the disputed patent (examples 11 to 16 and 20 to 26) with the data disclosed in Table I of (3) is also meaningless since the catalysts have been tested in reactors of different dimensions and design and under different conditions of pressure and contact time. As shown by the Respondent and not contested by the Appellant, DCE yields can be significantly affected by the reactor design at least at a pressure of 1 At. Furthermore the data of Table I concern a diluted catalyst containing only 2.5% copper and no promoter whereas the data of the opposed patent relate to promoted catalysts having a copper content of 5 wt%. Consequently, although the direct comparison shows an improvement of the DCE yield with respect to the diluted catalysts of (3), it cannot be deduced therefrom whether this improvement is attributable to the claimed solution, i.e. to the depletion of particle surface copper concentration to the claimed extent, or to the difference in the other parameters.

6.3.3. To support their opposite allegations, the parties have also referred to the comparative examples of the disputed patent, in which the performance of the claimed catalyst are compared with those of "prior art" catalysts A and B having no copper depletion on their surface (cf. Table 2 of the patent). As the HCl conversion drops much below 99% with HCl/C2H4 feed ratios higher than the stoichiometric requirements, only the results obtained with HCl/C2H4 ratios less than 2 are taken into consideration. From Table 2 it appears clearly that the fluidisation properties of the claimed catalysts remain excellent when the HCl/C2H4 ratio is raised up to values of 1.936 or 1.945. whereas the fluidisation behaviour of the prior art catalyst A is already bad at a HCl/C2H4 ratio of 1.936. A comparison of example 8 with examples 12 and 15 shows that the improvement of fluidisation quality is accompanied with an increase in the DCE yields (based on crude or on pure DCE) of about 0.9 or 1.2 points with respect to catalyst A. However, the corresponding HCl conversion is decreased by about 0.3 or 0.4 points although it remains over 99%. The tests of these examples were indeed performed at different temperatures and the catalysts according to the disputed patent contains a Mg salt whereas catalyst A is unpromoted. However, as indicated by the Appellant, the DCE yield is only about 0.2 to 0.3 points higher in the presence of MgCl2 and the HCl conversion is similar. Moreover operation at 220°C instead of 225°C seems not to decrease the DCE yield of the claimed catalyst (cf. Table 2bis of the Statement of Grounds).

It results from the preceding that in industrial exploitation a catalyst having its surface copper concentration reduced to the claimed extent has an improved fluidisation behaviour and gives slightly higher DCE yields than a catalyst without any copper depletion at the surface while the HCl conversion remains high. However, in the Board's opinion it cannot be derived therefrom that improvements would also be achieved with respect to a catalyst containing particles whose surface is already depleted of CuCl2 to a certain extent like the diluted catalyst of (3), i.e. with respect to the catalyst of the closest prior art. Accordingly, in the absence of evidence convincingly showing that the claimed catalysts lead to improved fluidisation characteristics and DCE yields with respect to the diluted catalysts of (3), the Board cannot consider that the problem defined by the Appellant has been credibly solved. Therefore the technical problem formulated in point 6.2 above (which has been effectively solved) is taken into consideration for the assessment of inventive step.

6.4. As already indicated above, document (3) is concerned with the problem of decreasing the catalyst stickiness which impairs the fluidisation characteristics of the bed. It teaches that the degree of stickiness is dependent on operating conditions such as pressure, temperature of the reaction, quantity and ratios of the gaseous reactants in the fluid bed and also on the catalyst characteristics such as porosity, amount and distribution of the copper on the particle surfaces, ratio of the weight of copper to the surface area of the support (cf. column 2, lines 24 to 45). Furthermore, according to document (8), the catalyst stickiness is caused by high concentrations of the copper salt on the outer surface of the support (cf. page 5, lines 15 to 25; examples 4, 7 and 8). The problem of stickiness is solved in (3) by mixing bare alumina support with the supported cupric chloride catalyst. It is clearly suggested in (3) that by reduction of the cupric chloride concentration on the outside surfaces of the supported catalyst and transfer of the released CuCl2 to the bare support stickiness of the catalyst particles is decreased and consequently the fluidisation characteristics are improved (see column 3, lines 20 to 48, column 7, lines 54 to 67; Claim 1). In view of this teaching the skilled person faced with the problem of providing a catalyst with excellent fluidisation behaviour in industrial exploitation (cf. point 6.2 above) would first of all contemplate solutions based on the same idea, i.e. reduction of the copper chloride concentration at the surface of the catalyst. As the extent of this reduction is not mentioned in (3), he would firstly determine this parameter and would then consider reducing the amount of particle surface copper chloride to different extents, in particular to a greater extent. Doing so, he would arrive by routine experimentation at the claimed solution. In this context the Board notes that the Appellant has neither contended nor proved that the method disclosed in (3) for depleting the catalyst surface of its active component to some extent (or other known general methods) could not lead to the degree of CuCl2 depletion defined in Claim 1.

The fact that not only excellent fluidisation properties but also high DCE yields and high HCl conversions are aimed at, would not deter the skilled person from carrying out experiments to determine the appropriate extent of the reduction of the CuCl2 amount at the catalyst surface since (3) does not contain any information or data suggesting that this reduction would negatively affect the DCE yield or the HCl conversion.

The Appellant's argument that there existed a prejudice against the reduction of copper chloride concentration on the catalyst surface because (3) discloses that CuCl2 is more uniformly distributed throughout the particles (cf. column 3, lines 33 to 39) cannot be followed by the Board. This passage concerns the distribution of CuCl2 on the particles of the bare alumina support added to the supported catalyst, not the distribution of CuCl2 in the diluted catalyst which also contains the supported catalyst particles with a reduced copper concentration at their surface. In this respect the Board observes that the surface atomic concentration of copper defined in Claim 1 results from a statistical measure (XPS-method) which does not permit distinguishing whether the catalyst consists of particles all having a reduced amount of copper at their surface or of a mixture of particles with different copper distributions. Therefore, the fact that the catalyst of (3) consists of such a mixture has no influence upon the preceding finding.

6.5. For the reasons given above, the Board considers that the catalyst as defined in Claim 1 of the main request does not involve an inventive step.

Auxiliary Request

7. Claim 1 differs from Claim 1 of the main request in that the catalyst is additionally defined by the two alternative methods for its preparation. There are no objections under Article 123(2) and (3) to this amended claim.

8. According to the established jurisprudence of the Boards of Appeal a claim defining a product in terms of a process is to be construed as a claim to the product as such. These claims are admissible only if the product as such fulfills the requirements for patentability (see for example T 150/82 OJ EPO 1984, 309). In the present case the catalyst per se is considered not to involve an inventive step for the reasons given above.

Furthermore it does not derive from the patent or from the Appellant's arguments that the operative features additionally recited in Claim 1 (in particular the dry impregnation of the preformed catalyst with a strong acid or the dry impregnation of the carrier with a copper salt solution and an acid) are critical for the obtention of a catalyst with the desired properties as regards fluidisation, DCE yields and HCl conversions in industrial exploitation. The Appellant himself attributed these properties to the claimed reduction of the copper amount at the surface of the catalyst.

The Board further notes that the operative features were considered as lacking inventive step by the Opposition Division (cf. point 32 of the decision under appeal) and that this finding was not contested by the Appellant in the Statement of Grounds or during oral proceedings.

Under these circumstances the Board comes to the conclusion that the subject-matter of Claim 1 according to the auxiliary request also does not meet the requirement of inventive step.

9. The dependent claims and the process claims fall with Claim 1 of each request.