In my opinion it's a question of style and I'd go along with what the client prefers. The brochure may well be published in several languages, so it may be important to maintain the same style in each.

That said, I don't see anything wrong with using quotation marks in this case.

HTH


Sheila

Please replace the double inverted comma or quotation mark (‘’x‘’) with an single inverted comma (‘x’) as suggested by Kim.

exposition /ɛkspozisjɔ̃/
feminine noun

(de tableaux, photos, d'objets d'art) exhibition;
(d'animaux, de plantes, marchandises) show;
(d'objets à vendre) fair;
(dans un magasin) display;
(de thèse, situation, faits) exposition;
(orientation) aspect;
la terrasse jouit d'une bonne ~ the terrace has a pleasant aspect;
(soumission à un effet) Phot exposure;
l'~ aux radiations/au soleil exposure to radiation/to sunlight.
http://www.wordreference.com/fren/exposition

e.g.: ‘Cathares : anges ou démons’ ? or
‘Cathares: angels or demons’? if translation is required.


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Note added at 3 days6 hrs (2012-05-13 13:42:17 GMT)
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In order to comply with Kim's targets, too (From my experience I know that he always finds a fly in the ointment, e.g. in my proposals), I do add a further proposal:

Exhibition ‘anges ou démons’?

Note: As I received a Disagree to my previous answer with double inverted commas (called Apostroph or Anführungszeichen in German) I modified my proposal accordingly and reposted it. Now the use of single inverted commas is critized (but only for my proposal).