**Craig Aldridge, Verónica Torregrosa-Rivero, Vicente Albaladejo-Fuentes, María-Salvadora Sánchez-Adsuar and María-José Illán-Gómez \***

Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Alicante, Ap. 99, E-03080 Alicante, Spain; craigald@hotmail.co.uk (C.A.); vero.torregrosa@ua.es (V.T.-R.); vicentealbaladejo@gmail.com (V.A.-F.); dori@ua.es (M.-S.S.-A.)

**\*** Correspondence: illan@ua.es; Tel.: +34-965903975

Received: 6 March 2019; Accepted: 16 April 2019; Published: 18 April 2019

**Abstract:** The effect of partial Ti substitution by Mn, Fe, Co, or Cu on the NOx storage capacity (NSC) of a BaTi0.8B0.2O3 lean NOx trap (LNT) catalyst has been analyzed. The BaTi0.8B0.2O3 catalysts were prepared using the Pechini's sol–gel method for aqueous media. The characterization of the catalysts (BET, ICP-OES, XRD and XPS) reveals that: i) the partial substitution of Ti by Mn, Co, or Fe changes the perovskite structure from tetragonal to cubic, whilst Cu distorts the raw tetragonal structure and promotes the segregation of Ba2TiO4 (which is an active phase for NOx storage) as a minority phase and ii) the amount of oxygen vacancies increases after partial Ti substitution, with the BaTi0.8Cu0.2O3 catalyst featuring the largest amount. The BaTi0.8Cu0.2O3 catalyst shows the highest NSC at 400 ◦C, based on NOx storage cyclic tests, which is within the range of highly active noble metal-based catalysts.

**Keywords:** perovskite; NO to NO2 oxidation; NOx storage capacity; LNT catalysts
