Analysis of nitrogen fixation by a catalyst capable of transforming N2, CO2 and CH4 into amino acids under mild reactions conditions

Abstract

The processes related to the fixation of nitrogen ina catalyst able to produce glycine and alanine from a N2, CO2and CH4gas mixture at mild reaction conditions have been studied by combining experimental and theoretical investigations.Results have allowed to understand the role of different elements of the catalyst, which is constituted by permanently polarized hydroxyapatite (p-HAp), zirconia, and aminotris(methylenephosphonic acid)(ATMP). ATMP attractsN2moleculestowards the surface,maintainingthem close to the zirconiaand p-HAp componentsthatare the most active from a catalytic point of view. On the other hand, the associative mechanismisthermodynamicallyfavouredunder mild reaction conditionswith respect to the dissociative one,whichis limited by the barrier associated to the N–Nbondcleavage. Because this reaction mechanism is similar to that employed in the nitrogen fixation bynitrogenase enzymes, thesefindingsprovide an opportunity to designnew bioinspired catalysts