M.P. Pina

Development and application of perovskite‐based catalytic membrane reactors

The preparation and characterization of catalytic membranes containing La‐based perovskites are reported. The membranes were prepared by in situ crystallization of different perovskites inside a porous α‐alumina matrix. Preponderance of the Knudsen‐diffusion regime during membrane operation was obtained with perovskite loads of 2 wt% and higher. The catalytic membranes obtained were used as combustors of VOCs (toluene and methyl ethyl ketone) contained in air streams, at concentrations between 875 and 3450 ppmV, and space velocities of up to 27200 h-1. The membranes were operated in the flow‐through mode, which resulted in total VOC combustion at moderate temperatures.

Explosives Detection by array of Si μ-cantilevers coated with titanosilicate type nanoporous materials

An array comprising four Si μ-cantilevers coated with nanoporous functionalized ETS-10 crystals sub-micrometric in size has been developed as a multisensing platform for explosives recognition in vapor phase. The detection capabilities of the proposed device have been tested for common taggants [such as 1-methyl-2-nitro-benzene (o-MNT)] and explosives (commercial detonation cord, a plastic tube filled with pentaerythritol tetranitrate (PETN); and C-4, a mixture of cyclotrimethylenetrinitramine (RDX), binders and plastifiers). The general strategy for the detection of explosives in vapor phase is based on the characteristic fingerprint each one produces as a result of the dissimilar chemical interactions between the ETS-10 coated μ-cantilevers and the target molecules emanating from the explosives and swept by ambient air. A portable lock-in amplifier has been implemented to exploit the truly benefits of the array in terms of portability, reduced size, and energy consumption. Such low-power electronic interface is capable of creating the excitation signal as well as obtaining the response values of four resonating μ-cantilevers simultaneously. The resulting sensing platform has successfully been applied for the o-MNT, PETN, and RDX detection at trace level.

Portable lock-in amplifier for microcantilever based sensor array. Application to explosives detection using Co-BEA type zeolites as sensing materials

Recent advances in microcantilever-based sensors have led to a significant increase in sensitivity, making them a competitive solution in highly demanding applications as explosives detection. However, these sensors face severe challenges related to: reliability, sensitivity, reproducibility and throughput; that have yet to be solved for commercial applications. This paper describes our efforts in this direction, particularly on the reproducible detection of nitroaromatic type explosives by means of parallelization combined with: i) nanoporous solids as sensing materials; and, ii) a portable low-power electronic readout interface capable of both excitation and measurement of the multisensing platform. The response of the sensor array, comprising 4 microcantilevers, due to presence of 2-nitrotoluene, a common explosive taggant, has been properly monitored. The obtained results with 4 identical Co-BEA coated Si microcantilevers underline the importance of a proper sensing material degassing on the sensor performance.

Grace: Development of Pd-Zeolite Composite Membranes for Hydrogen Production by Membrane Reactor

This chapter presents the development of Pd-zeolite composite membranes for hydrogen production by membrane reactor. Pd-zeolite composite membranes are prepared over the external surface of macroporous α-alumna tubular supports by secondary growth of zeolite layers followed by Pd modification. Pd nanoparticles filtration and/or impregnation + in situ reduction of an organic Pd precursor are explored as deposition techniques devoted to enhance the H 2 separation performance of the non-defect free A-type zeolite membranes. The Pd deposition aims toward the partial blockage of the non-selective intercrystalline pathways, which may account for a significant fraction of the total permeation flux. The Pd-zeolite composite substrates are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and EDX. The study of the permeation properties of these substrates for single (N 2 ) and binary mixtures (H 2 –CO 2 ) before and after Pd modification reveals some improvements in terms of H 2 separation performance. The impregnation + in situ reduction of palladium acetylacetonate solution (Pd(acac) 2 ) carried out over KA zeolite membranes previously seeded with Pd nanoparticles appears as the most adequate among the tested methods. Separation factors for H 2 -CO 2 binary mixtures up to 145 have been achieved, although further optimization is required to improve the H 2 permeation fluxes (around 10 −8 mol H 2 /m 2 s Pa).