Copper Catalysts Supported on Barium Deficient Perovskites for CO Oxidation Reaction

Mixed oxides with perovskite-type structure (ABO3) present interesting physico-chemical properties to be used as catalyst for atmospheric pollution control. In this work, a series of CuX/Ba0.7MnO3 catalysts (being x: 0, 4, 8 and 12 wt%) has been synthesized, characterized and tested for CO oxidation reaction. All the catalysts were active for CO oxidation in the two reactant mixtures tested: low CO mixture (0.1% CO and 1% O2 in He) and near stoichiometric mixture (1% CO and 1% O2 in He). Copper-free perovskite is the most active catalyst in the less demanding conditions (0.1% CO and 1% O2), as it presents the highest amount of oxygen vacancies working as active sites. However, at higher CO concentrations (1% CO in near stoichiometric mixture), copper-containing catalysts were more active than the perovskite support because, due to the saturation of the oxygen vacancies of perovskites, CuO seems to participate as active site for CO and O2 activation. Cu4/Ba0.7MnO3 and Cu12/Ba0.7MnO3 are more active than Cu8/Ba0.7MnO3 catalyst, since they present a larger amount of active sites on surface. These two copper-containing catalysts present a high stability and recyclability during the reaction at 300 °C in an ideal near stoichiometric mixture (1% CO and 1% O2).Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by Ministerio de Ciencia,Innovación y Universidades, (Grant No. PID2019-105542RB-I00), María José Illán Gómez, European Regional Development Fund, Generalitat Valenciana, (Grant No. CIPROM/2021-070 project), María José Illán Gómez, Universidad de Alicante

Analyzing the role of copper in the soot oxidation performance of BaMnO3-perovskite-based catalyst obtained by modified sol-gel synthesis

A series of BaMn0.7Cu0.3O3 solids were prepared by a modified sol-gel method in which carbon black (VULCAN XC-72R), and different calcination temperatures (BMC3-CX, where X indicates the calcination temperature) have been used. The fresh and used catalysts were characterized by ICP-OES, XRD, XPS, FESEM, TEM, O2-TPD and H2-TPR. The presence of a carbon black during sol-gel synthesis of BMC3 mixed oxide allows diminishing the calcination temperature needed to achieve the perovskite structure, but it hinders the formation of the BaMnO3 polytype. The use of low calcination temperatures during synthesis reduces the sintering effects, and the mixed oxides present lower particle size, slightly higher BET surface areas and macropores with lower diameter than BMC3. The distribution of copper in BMC3-CX catalysts depends on the calcination temperature and copper insertion into the perovskite structure is promoted as the calcination temperature increases. All BMC3-CX catalysts are active for NO to NO2 and NOx-assisted soot oxidation processes, but only BMC3-C600 and BMC3-C700 show higher catalytic activity than BMC3 reference catalyst. BMC3-C600 presents the best performance as it features a high amount of surface copper and oxygen vacancies that increase during reaction. The comparison between the performance of the two best catalysts of the BM-CX series (BM-C700) and the BMC3-CX series (BMC3-C600) suggests that the unique advantage of using copper in the modified sol-gel synthesis is an additional decrease of 100 °C in the calcination temperature used for the synthesis of the best catalyst, which is 700 °C for BM-CX and 600 °C for BMC3-CX.This research was funded by Spanish Government (PID2019-105542RB-I00) and EU (FEDER Founding)

Modified BaMnO3-Based Catalysts for Gasoline Particle Filters (GPF): A Preliminary Study

Gasoline engines, mainly gasoline direct injection engines (GDI) require, in addition to three-way catalysts (TWC), a new catalytic system to remove the formed soot. Gasoline Particle Filters (GPF) are, among others, a possible solution. BaMnO3 and copper-doped BaMnO3 perovskites seem to be a feasible alternative to current catalysts for GPF. The physical and chemical properties of these two perovskites determining the catalytic performance have been modified using different synthesis routes: (i) sol-gel, (ii) modified sol-gel and iii) hydrothermal. The deep characterization allows concluding that: (i) all samples present a perovskite-like structure (hexagonal), except BMC3 which shows a polytype one (due to the distortion caused by copper insertion in the lattice), and ii) when a low calcination temperature is used during synthesis, the sintering effect decreases and the textural properties, the reducibility and the oxygen mobility are improved. The study of soot oxidation simulating the hardest GDI scenarios reveals that, as for diesel soot removal, the best catalytic performance involves the presence of oxygen vacancies to adsorb and activate oxygen and a labile Mn (IV)/Mn (III) redox pair to dissociate the adsorbed oxygen. The combination of both properties allows the transport of the dissociated oxygen towards the soot.This research was funded by Generalitat Valenciana (CIPROM/2021/70), Spanish Government (PID2019-105542RB-I00) and EU (FEDER Founding)

Exploring the effect of using carbon black in the sol-gel synthesis of BaMnO3 and BaMn0.7Cu0.3O3 perovskite catalysts for CO oxidation

BaMnO3 and copper-doped BaMnO3 perovskites seem to be a feasible alternative to current catalysts for the exhaust treatment. In this work, these formulations have been synthesized by a modified sol-gel method in which carbon black has been added to the conventional sol-gel process in order to improve the physical and chemical properties that modulate the catalytic performance. The samples have been deeply characterized by ICP-OES, XRD, XPS, H2-TPR and O2-TPD. The characterization results point out that the use of carbon black allows decreasing the calcination temperature which minimizes the sintering effects and improves the textural properties, the reducibility, and the oxygen mobility. The study of CO oxidation, using different simulated atmospheres, reveals that all the catalysts were active for CO to CO2 oxidation, but only when oxygen is supplied in excess, an effect of the synthesis method is observed. Additionally, as expected, the presence of copper (inserted or not into the perovskite lattice) benefits the catalytic performance. Otherwise, it seems that the catalytic performance for CO oxidation of BaMnO3-based samples is less affected by the fluctuations of CO and O2 concentrations than the platinum-based catalyst used as reference

BaFe1−xNixO3 Catalysts for NOx-Assisted Diesel Soot Oxidation

In this work, it is analyzed the effect of the partial substitution of Fe by Ni in a BaFeO3 perovskite to be used as the catalyst for NOx-assisted diesel soot oxidation. A series of BaFe1−xNixO3 (x = 0, 0.2, 0.4 and 0.8) catalysts have been synthesized by using the sol–gel method. The catalysts have been characterized by ICP-OES, XRD, XPS, O2-TPD, H2-TPR- and TEM. The catalytic activity for NO to NO2 oxidation and NOx-assisted diesel soot oxidation have been determined by Temperature Programmed Reaction experiments (NOx -TPR and Soot-NOx-TPR, respectively) and by isothermal reaction at 450 °C. Ni seems not to be inserted in the BaFeO3 perovskite and, instead of that, BaNiO3 perovskite and NiO are detected on the surface of the perovskite BaFeO3. XPS data reveal the coexistence of Fe(III) and Fe(IV) on the catalyst’s surface (being Fe(III) the main oxidation state) and the presence of oxygen vacancies. All catalysts are active for NO oxidation to NO2, showing BaFeO3 and BaFe0.6Ni0.4O3 the best catalytic performance. BaFe0.6Ni0.4O3 shows the highest proportion of nickel on surface and it combines the highest activity and stability for NOx-assisted diesel soot oxidation. Also, this catalyst presents the highest initial soot oxidation rate which minimizes the accumulation of unreacted soot during reaction.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This study was funded by the Spanish Government (MINCINN: PID2019-105542RB-I00/AEI/10.13039/501100011033 Project), by the European Union (FEDER Funds), by the Regional Government (Generalitat Valenciana CIPROM/2021-070 project) and by the University of Alicante (Final Master’s Project grant of S. Montilla-Verdú)

BaFe1−xCuxO3 Perovskites as Active Phase for Diesel (DPF) and Gasoline Particle Filters (GPF)

BaFe1−xCuxO3 perovskites (x = 0, 0.1, 0.3 and 0.4) have been synthetized, characterized and tested for soot oxidation in both Diesel and Gasoline Direct Injection (GDI) exhaust conditions. The catalysts have been characterized by BET, ICP-OES, SEM-EDX, XRD, XPS, H2-TPR and O2-TPD and the results indicate the incorporation of copper in the perovskite lattice which leads to: (i) the deformation of the initial hexagonal perovskite structure for the catalyst with the lowest copper content (BFC1), (ii) the modification to cubic from hexagonal structure for the high copper content catalysts (BFC3 and BFC4), (iii) the creation of a minority segregated phase, BaOx-CuOx, in the highest copper content catalyst (BFC4), (iv) the rise in the quantity of oxygen vacancies/defects for the catalysts BFC3 and BFC4, and (v) the reduction in the amount of O2 released in the course of the O2-TPD tests as the copper content increases. The BaFe1−xCuxO3 perovskites catalyze both the NO2-assisted diesel soot oxidation (500 ppm NO, 5% O2) and, to a lesser extent, the soot oxidation under fuel cuts GDI operation conditions (1% O2). BFC0 is the most active catalysts as the activity seems to be mainly related with the amount of O2 evolved during an. O2-TPD, which decreases with copper content

BaTi0.8B0.2O3 (B = Mn, Fe, Co, Cu) LNT Catalysts: Effect of Partial Ti Substitution on NOx Storage Capacity

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.This research was funded by Generalitat Valenciana (PROMETEO/2018/076 and Ph.D. grant ACIF 2017/221), Spanish Government (MINECO Project CTQ2015-64801-R) and EU (FEDER Founding)

BaFe1-xCuxO3 Perovskites as Active Phase for Diesel (DPF) and Gasoline Particle Filters (GPF)

BaFe1-xCuxO3 perovskites (x = 0, 0.1, 0.3 and 0.4) have been synthetized, characterized and tested for soot oxidation in both Diesel and Gasoline Direct Injection (GDI) exhaust conditions. The catalysts have been characterized by BET, ICP-OES, SEM-EDX, XRD, XPS, H2-TPR and O2-TPD and the results indicate the incorporation of copper in the perovskite lattice which leads to: i) the deformation of the initial hexagonal perovskite structure for the catalyst with the lowest copper content (BFC1), ii) the modification to cubic from hexagonal structure for the high copper content catalysts (BFC3 and BFC4), iii) the creation of a minority segregated phase, BaOx-CuOx, in the highest copper content catalyst (BFC4), iv) the rise in the quantity of oxygen vacancies/defects for the catalysts BFC3 and BFC4, and v) the reduction in the amount of O2 released in the course of the O2-TPD tests as the copper content increases. The BaFe1-xCuxO3 perovskites catalyze both the NO2-assisted diesel soot oxidation (500 ppm NO, 5% O2) and, to a lesser extent, the soot oxidation under fuel cuts GDI operation conditions (1% O2). BFC0 is the most active catalysts as the activity seems to be mainly related with the amount of O2 evolved during an. O2-TPD, which decreases with copper content.This research was funded by the Generalitat Valenciana (PROMETEO/2018/076 and Ph.D. Grant ACIF/2017/221 for V.Torregrosa-Rivero), Spanish Government (MINECO Project CTQ2015-64801-R), and EU (FEDER Founding)

Cultivando el emprendimiento en estudiantes de primer curso de Química

En el presente trabajo, desarrollado en el seno de la asignatura operaciones básicas de laboratorio II (OBLII), se ha llevado a cabo la adquisición de competencias emprendedoras por parte de estudiantes de primer curso de la titulación de química mediante un programa de tutorización realizado por estudiantes de postgrado y últimos cursos de la titulación. Con esta actividad se pretende iniciar a los estudiantes de primer curso en actividades que fomenten el espíritu emprendedor a través del trabajo en equipo, la capacidad de comunicación oral y escrita, y la evaluación crítica de su propio trabajo y el de sus compañeros. Para desarrollar esta actividad los estudiantes de primer curso han realizado un trabajo bibliográfico en equipos de cuatro componentes que han sido supervisados por parte de los estudiantes senior. Con el objetivo de provocar la reflexión de los estudiantes de primer curso en las tres competencias fundamentales del proyecto (trabajo en equipo, comunicación y evaluación objetiva), los grupos de trabajo han participado en tres dinámicas de trabajo, dirigidas por los estudiantes senior, basadas en cada una de esas tres competencias emprendedoras. Los resultados de esas dinámicas y la opinión de los estudiantes sobre las mismas se recogen en el presente trabajo

OBLII_2016

En la asignatura OBLII, impartida en el primer curso del Grado en Química, se desarrolla un trabajo bibliográfico en equipo supervisado por un estudiante de postgrado o cursos superiores de la titulación (estudiante-tutor). Hasta el curso 2014/15, el seguimiento de este trabajo y la comunicación entre el equipo de trabajo, profesor y estudiante-tutor se ha realizado mediante reuniones y tutorías presenciales. En el presente curso, se ha empleado la red social Facebook como herramienta de comunicación entre las diferentes figuras implicadas en el citado trabajo colaborativo; y se han llevado a cabo una serie de tutorías no presenciales y debates a través de dicha plataforma. Para llevar a cabo las citadas actividades, se han creado dos tipos de grupos privados en Facebook: un grupo general para todos los estudiantes, estudiantes-tutores y profesores; y otro grupo por cada equipo de trabajo formado por cuatro estudiantes y su estudiante-tutor. Las actividades realizadas a través de esta plataforma han sido utilizadas por los estudiantes-tutores para evaluar la competencia “trabajo en equipo”, recogida en la guía de la asignatura. En el presente trabajo, se muestran los resultados obtenidos en los citados grupos de Facebook, así como la opinión de sus miembros sobre el proyecto