Foreign Currency Exchange Rates at PEK

Next month we are flying to Taiyuan with a stop-over at PEK (we land very early in the morning, we don't have the details on the domestic flight yet), since it's supposed to be much cheaper to Exchange EUR to RMB in China instead of my home country (Netherlands) we want to exchange a considerable amount in cash (5-6000 EUR) as soon as we land. Is there an official rate that's being used (i.e. the BoC cash Exchange rates?), or can each branche office use its own rates ?