Shedding certain belongings can frequently follow a marital split. In the case of art collector Charles Saatchi, whose decree nisi in his divorce from food writer Nigella Lawson was granted this week, a clearout will be on a grand scale.

He is planning an auction of 50 of his largest sculptures and installations, including a full-size four-poster with embroidered hangings by Tracey Emin.

According to Philippa Adams, senior director of the Saatchi Gallery in London, the sale on 17 October, which will take place under the auspices of Christie's, has "absolutely nothing to do with the divorce. We have been working on this for a long time. I can categorically state that".

Instead, the auction of artworks will support the Saatchi Gallery's education programme and free access to its exhibitions, she said. Ideally, the works will be bought by public collections. "We think it's really important to open things up and give museums a chance to have a crack at acquiring these works – they need to be enjoyed and shown."

The works for sale – all so large that they will be exhibited in a disused London postal depot instead of Christie's HQ – will coincide with this year's Frieze art fair. They include sculptures by celebrated German artist Isa Genzken, the Belgian artist Berlinde de Bruyckere, Scot Karla Black and Canadian David Altmejd, all of whom have recently represented their countries at the Venice Biennale.

What makes the sale different from any Christie's auction since the 1970s is that no lot will have a reserve price or estimate – an idea that came from Saatchi himself, according to Francis Outred, head of postwar and contemporary art at Christie's.

Normally, if a work fails to realise its reserve price, it is removed from sale. Without a reserve (often the lower figure of the auction house's estimated price range) there could be some bargains for public institutions – and corresponding embarrassment for living artists. In practice, according to art-world expert Louisa Buck, the artists' own dealers will be "poised like cobras" to bid on the works, if necessary purchasing them if they show signs of selling for low prices. "Galleries won't want to see their artists' prices take a nosedive."

She said: "Nothing Saatchi does is without some kind of strategy or agenda. This looks like grandstanding to me, another game he is playing: trying perhaps to keep in the public eye in a more responsible way than he has done recently. It rings with the tenor of the times that they are talking about the proceeds going into access and education.

"If he was really serious about these works going into public collections he would be approaching institutions individually and offering them for a reasonable price, or indeed for no price at all."

Adams said: "It is absolutely not a grandstanding stunt. We have huge care and respect for the artists. [A stunt] would be hugely disrespectful to the artists." They had decided to auction them because "we don't have access to all the museums and galleries who might want to acquire works – and we want it to be an open platform".

The Saatchi collection had always been "fluid" and "never static" with works sold from time to time to allow funds to support up-and-coming artists.

Outred, of Christie's, said the living artists' reputations was of "very real concern" and "we have had a couple of discussions with artists. We will treat this as responsibly as we can." He added: "We want everything to go to a good home."

He conceded that "we can't control who will buy the works" and where they end up; many are likely to be bought overseas. But Christie's would be in close contact with public institutions and offer them "special payment terms"– in monthly instalments rather than in full after 30 days.

Stephen Deuchar, director of the art charity the Art Fund, which helps publicly funded British museums and galleries purchase contemporary art, expressed concern about the stated aims of the auction. He described it as a "market free-for-all", and said "very few museums have acquisition funds readily available" particularly in the economic climate.

"Of course we applaud the principle of free admission to museums and galleries whenever it can be realistically achieved, though selling off a collection to this end is an unusual strategy. Meanwhile I'm not sure exactly how this sale relates to the Saatchi Gallery's collecting policy – are these works simply the ones that are no longer wanted?"