Hybrid Catalysts Supported in Polymeric Membranes for Sustainable Chemical Process Applications

V. Esquivel-Peña, J. Bastos-Arrieta, M. Muñoz, N. Munguía Acevedo, A.L. Ocampo, J. de Gyves
Universidad Nacional Autónoma de México (UNAM),
Mexico

Keywords: hybrid catalysts, metal nanoparticles, carbon nanotubes, polymeric membranes

Summary:

The development of catalysts is closely related to the sustainability of a chemical process since their use usually allows to increase the selectivity and reduce the energy of a chemical process. The unique properties that metal nanoparticles (MNPs) exhibit combined with the specific properties of carbon nanomaterials has derived in an enormous attention in many fields such as heterogeneous catalysis [1]. Nowadays, interesting advantages are reported to be obtained with the development of bimetallic nanoparticles where the use of another metal allows to enhance their catalytic activity reducing the cost of the catalyst. An important challenge in heterogeneous catalysis is the recovery of the catalyst from the liquid reaction media to reduce the environmental impact. In this work, firstly, to improve the catalytic activity of the MNP-CNTs, CNTs were functionalized with nitric acid. Then the synthesis and incorporation of copper nanoparticles (NPs)s and copper/platinum bimetallic NPs into multiwall carbon nanotubes (CNT) was carried out using the intermatrix synthesis technique [2] for the charge of the first metal and a procedure known as galvanic replacement [3] for the deposition of a second metal to form bimetallic NPs. TEM characterization demonstrate a homogeneous distribution of the MNPs along the CNTs with the latter (mean particle diameter 4.3 ± 1.3 nm). Once the MNPs-CNTs were obtained, they were incorporated into a polymeric membrane (PM) based on cellulose triacetate. All materials were characterized by FTIR, TGA, XRD and TEM. PMs were characterized by SEM. The metal content was determined also via ICP-OES. The catalysts obtained were tested making use of the 4-nitrophenol reduction to 4-aminophenol as a model reaction. The reduction was carried out with sodium borohydride as the reducing agent. At least 90% of the total amount of 4-nitrophenol was reduced during the first hour. Moreover, the reaction medium was further analyzed by ICP-OES and no evidence of the contamination with the catalyst were found. These results demonstrated the capability to perform a sustainable process with the developed catalyst, reducing the purification cycles of the product, applicable to environmental and fine chemical synthesis processes. Acknowledgements This work was supported by DGAPA-UNAM (project IN116017). V.Esquivel(Exp. Num. 292787), gratefully thanks CONACyT for doctoral and “Beca Mixta” scholarships. Gratitude is also expressed to the technical services of the Universidad Nacional Autónoma de México (R. Iván Puente Lee, Víctor H. Lemus Neri, M. Cecilia Salcedo Luna, USAI-FQ, UNAM), to Servei de Microscopia from Universitat Autònoma de Barcelona, to Dr. Gustavo Lopez Tellez (Centro Conjunto de Investigacion en Quimica Sustentable, CCIQS-UAEMex), for the XPS analysis and Dra. Guillermina Burillo and Alejandra Ortega (ICN-UNAM) for thermal analysis. References [1] P. Serp, M. Corrias, P. Kalck, Appl. Catal., A, 253 (2003) 337-358. [2] J. Bastos-Arrieta, J. Munoz, A. Stenbock-Fermor, M. Munoz, D.N. Muraviev, F. Cespedes, L.A. Tsarkova, M. Baeza, Appl. Surf. Sci., 368 (2016) 417-426. [3] W.J. Plieth, J. Phys. Chem., 86 (1982) 3166-3170. This work was supported by DGAPA-UNAM (project IN116017) and the Swedish Research Council project 2014-1744-114656-30. V. Esquivel (Exp. Num. 292787), gratefully thanks CONACyT for doctoral and “Beca Mixta” scholarships. Gratitude is also expressed to the technical services of the Universidad Nacional Autónoma de México (R. Iván Puente Lee, Víctor H. Lemus Neri, M. Cecilia Salcedo Luna, USAI-FQ, UNAM), to Servei de Microscopia from Universitat Autònoma de Barcelona, to Dr. Gustavo Lopez Tellez (Centro Conjunto de Investigacion en Quimica Sustentable, CCIQS-UAEMex), for the XPS analysis and Dra. Guillermina Burillo and Alejandra Ortega (ICN-UNAM) for thermal analysis.