One of the most efficient analysis technique is to reduce an original model into a simpler one such that the reduced model has the same properties than the original one. G. Berthelot defined in this thesis some reductions of Petri nets that are based on local structural conditions and that simplify significantly the net. However, the author focused only on the preservation of classical properties (such that liveness, boundedness, ...) that are not necessarily the most useful in practice. In this paper, we prove that two of these structural reductions (the pre and post transitions agglomerations) preserve also a large set of properties expressed in linear-time temporal logics under simple conditions.