NO + CO reaction over LaCu 0.7 B 0.3 O 3 (B 5 Mn, Fe, Co) and La 0.8 A 0.2 Cu 0.7 Mn 0.3 O 3 (A 5 Rb, Sr, Cs, Ba) perovskite-type catalysts Ali Tarjomannejad 1 • Aligholi Niaei 1 • Marı ´a Jose ´ Illa ´n Go ´mez 2 • Ali Farzi 1 • Dariush Salari 3 • Vicente Albaladejo-Fuentes 2 Received: 17 July 2016 / Accepted: 6 March 2017 Ó Akade ´miai Kiado ´, Budapest, Hungary 2017 Abstract In this paper, catalytic reduction of NO by CO over perovskite-type oxides LaCu 0.7 B 0.3 O 3 (B = Mn, Fe, Co) synthesized by sol–gel method was investigated. LaCu 0.7 Mn 0.3 O 3 showed the highest activity among LaCu 0.7 B 0.3 O 3 perovskite catalysts (88% CO conversion and 93% NO conversion at 350 °C). The effect of alkali and alkaline earth metals (Rb, Sr, Cs and Ba) on the structure and catalytic activity of LaCu 0.7 Mn 0.3 O 3 per- ovskite catalysts was also investigated. The results showed that catalytic activity was improved by partial substitution of La by alkali and alkaline earth metals. The superior activity of La 0.8 Sr 0.2 Cu 0.7 Mn 0.3 O 3 with respect to other catalysts (93% CO conversion and 96% NO con- version at 350 °C) was associated with a higher reducibility at low temperature, more oxygen vacancies and synergistic effect between Cu and Mn. The catalysts were characterized by XRD, BET, H 2 -TPR, XPS and SEM. Keywords NO reduction Á CO Á Sol–gel Á Perovskite Á LaCu 0.7 B 0.3 O 3 Á La 0.8 A 0.2 Cu 0.7 Mn 0.3 O 3 Introduction The emission of nitrogen oxides and carbon monoxide from motor vehicles is an important issue in environmental protection and public health. NO should be selectively converted to N 2 instead of NO 2 or N 2 O, that are toxic or greenhouse gasses [1, 2]. One of the effective ways to reduce NO and CO is catalytic reduction of NO by CO [3, 4]. Precious metals Pt, Pd and Rh supported on alumina and ceria have been considered as the most efficient for the control of exhaust gas [5, 6]. Due to their high cost and low stability, considerable efforts have been paid to the uti- lization of perovskite catalysts [7–9]. Perovskite mixed oxides with ABO 3 formula have high activity for the control of exhaust gas emissions [10]. A is usually an alkali, alkaline earth or lanthanide metal ion [11–13]. One of the advantages of the perovskite structure is the possi- bility of partial substitution of each A and/or B cation by others with the same or different valence (general formula A 1-x A 0 x B 1-y B 0 y O 3-d )[14–16]. Therefore, by an appro- priate selection of A 0 and B 0 cations, a catalyst with a high activity for desired reaction requirements can be achieved. Perovskites with La in A site and a first series transition metals in B site are very active for reduction of NO by CO [17–19]. La can be partially substituted by other ions such as alkali or alkaline earth. If the La 3? ion is partially substituted by cations with lower valence, the perovskite lattice is distorted and structural defections are formed, resulting in an enhancement of lattice oxygen mobility and the catalytic properties of active B cation [20–22]. Sub- stitution at La 3? with Rb 1? , Cs 1? , Sr 2? and Ba 2? ions can allow the formation of structural defects such as anionic vacancies and a change in the oxidation state of the & Ali Farzi a-farzi@tabrizu.ac.ir 1 Catalyst and Reactor Research Group, Department of Chemical and Petroleum Engineering, University of Tabriz, Tabriz, Iran 2 Carbon Materials and Environment Research Group, Department of Inorganic Chemistry, Faculty of Science, Universidad de Alicante, Alicante, Spain 3 Department of Applied Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran 123 J Therm Anal Calorim DOI 10.1007/s10973-017-6264-x