Abstract A stable nitrogen‐rich porous polyimine containing pyridine units ( PIPy‐4Mw ) was successfully synthesized under microwave heating via a simple “one‐step” polycondensation in only 30 min without adding any catalyst. This versatile polymer can incorporate different transition metals leading polyiminopyridine‐supported catalysts; in this paper we report the synthesis and catalytic performance of heterogenized complexes of abundant earth metals such as iron(II), cobalt(II) and chromium(III) ( PIPy‐4MwFe , PIPy‐4MwCo and PIPy‐4MwCr ). These supported metal‐polyiminopyridines have been applied as heterogeneous catalysts in the conversion of CO 2 into cyclic carbonates, an interesting reaction to recycle CO 2 , and in another eco‐friendly reaction: the synthesis of additives for diesel fuels by acetalization of furfural. The cobalt and iron complexes have showed high efficiency and were reused without any significant change in their activities.