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Catalysts are quantum systems that open up dynamical pathways between quantumstates which are otherwise inaccessible under a given set of operationalrestrictions while, at the same time, they do not change their quantum state.We here consider the restrictions imposed by symmetries and conservation laws,where any quantum channel has to be covariant with respect to the unitaryrepresentation of a symmetry group, and present two results. First, for anexact catalyst to be useful, it has to build up correlations to either thesystem of interest or the degrees of freedom dilating the given process tocovariant unitary dynamics. This explains why catalysts in pure states areuseless. Second, if a quantum system ("reference frame") is used to simulate tohigh precision unitary dynamics (which possibly violates the conservation law)on another system via a global, covariant quantum channel, then this channelcan be chosen so that the reference frame is approximately catalytic. In otherwords, a reference frame that simulates unitary dynamics to high precisiondegrades only very little.

Covariant catalysis requires correlations and good quantum reference frames degrade little