The development of materials at CNR-STEMS is mostly devoted to process intensification in the context of sustainability, in particular the low carbon technologies and the emissions control. Materials are designed at nano-scale level suitably tuning the properties through morphological, physico-chemical and functional characterization. The development of the catalyst/sorbent spans from the nano-scale up to process modelling and pilot testing according to an engineered multi-scale approach. The new materials are suitably designed with chemical and physical properties and functionalities tailored for specific applications. Among the main applications there are: Power to Gas, thermochemical cycles (chemical looping combustion/reforming/methanation, H2O/CO2 thermochemical splitting), purification of natural gas and bio-gas, exhaust after-treatment for diesel/gasoline engines, DeNOx, VOC abatement, CO2 capture, Hg/H2S removal, steam/dry/tri-reforming, poisoning tolerance and regeneration of catalysts, upgrading of by-products and wastes. Some examples of research activities focused on energetic and environmental applications at CNR-STEMS will be described along with the available techniques to characterize the materials and suitably address formulation and synthesis to optimize the performance. The first one is the development of Dual Function Materials (DFM) for chemical looping process of CO2 capture and hydrogenation to produce Synthetic Natural Gas (SNG). Catalysts with low Ru loading (< 1 % wt.) dispersed on Al2O3 spheres were promoted with variable amounts of Li (1-5 % wt.). The spontaneous formation of mixed lithium-aluminate phases effectively prevented the formation of highly stable carbonate species, peculiar of other alkali or alkaline-promoted DFMs, which are difficult to hydrogenate [1, 2]. The favourable synergism occurring at the nanoscale level between the Li-aluminate sorbent phase and the catalytic Ru sites enhanced the intrinsic activity of the DFMs that can guarantee high methane productivity and selectivity with low noble metal loadings. In addition to standard characterization techniques, results of in situ techniques (TG-MS, DRIFT), fundamental in the definition of the reaction mechanism, will be discussed. The role of textural and morphological properties of geopolymer based monoliths produced by additive manufacturing method (Direct Ink Writing), with the introduction of up to 60% by weight of pre-synthetized ZSM-5 into the extrusion ink, will be described to highlight the effect of hierarchical porosity in the NH3-SCR of NOx [3]. The catalyst, with a good mechanical resistance provided by the geopolymer, was exchanged with copper which was found preferentially located at the typical exchange sites in the zeolitic structure. These represent the active sites for the SCR reaction, whereas the formation of extra-framework CuO, detected for the pure geopolymer monolith, was minimized in the composite. The significant enhancement of the performance of the geopolymer-zeolite composites with respect to a pure self-sustained ZSM-5 foam monolith [4] appeared to benefit from their hierarchical structure given by the simultaneous presence of a macro/mesoporous (geopolymer) and a microporous (zeolite) phases. In particular, the results of porosimetric and TPD/TPR analyses and the effect on the SCR performance will be described. A special case focusing on the morphological aspects of the catalysts is represented by the issue of the contact between the catalytic CeO2 phase dispersed a SiC diesel particulate filter (DPF) and soot produced by diesel engine which are the two reactants of a solid-solid reaction. The oxidation temperature of soot can be significantly lowered provided that an effective contact between catalyst and soot is established. Nevertheless, solid-solid contact is not a trivial matter and suitable dimensions of catalysts particles and a proper dispersion are fundamental. The use of nanometric CeO2 particles as catalyst, suitably dispersed into the filter, resulted in excellent performance of the catalytic DPF assuring a tight contact with the soot particles without occluding the pores thus preserving the mechanical filtration properties of the DPF and activating soot oxidation at temperature close to that of the exhaust gases [5, 6]. Results of the porosimetric and SEM/EDS analysis to define the optimal amount and dispersion of CeO2 will be discussed. Finally, as last case, sorbents based on highly dispersed CuO-ZnO onto activated carbon for H2S removal from biogas at room temperature will be presented [7]. TPD/TPO experiments from partially and completely saturated sorbents allowed the speciation of adsorbed sulfur species, arising from the complexity of the surface reactions which, in turn, strongly depended on the Zn:Cu ratio, on the interactions of metal oxides with activated carbon and on the textural properties of the sorbent [8]. In particular, the additional catalytic role of copper, located into the carbon micropores, in the presence of H2O and O2, determining an increase in H2S capture rate, was analysed through the use of different techniques to investigate the extensive formation of different sulfur species in the exhaust sorbents under conditions close to the real ones [9]. [1] S. Cimino, F. Boccia, L. Lisi, J. CO2 Util. 37 (2020) 195-203. [2] S. Cimino, R. Russo, L. Lisi, Chem. Eng. J. 428 (2022) 131275. [3] E. M. Cepollaro, R. Botti, G. Franchin, L. Lisi, P. Colombo, S. Cimino, Catalysts 11 (2021) 1212. [4] N. Gargiulo, D. Caputo, G. Totarella, L. Lisi, S. Cimino, Catal. Today 304 (2018) 112-118. [5] V. Di Sarli, G.Landi, L. Lisi, A. Saliva, A. DI Benedetto, Appl. Catal. B 197 (2016) 116-124. [6] V. Di Sarli, G.Landi, L. Lisi, A. DI Benedetto, AIChE J. 63 (2017) 3442-3449. [7] M. Balsamo, S. Cimino, G. de Falco, A. Erto, L. Lisi, Chem. Eng. J. 304 (2016) 399-407. [8] G. de Falco, F. Montagnaro, M. Balsamo, A. Erto, F. A. Deorsola, L. Lisi, S. Cimino, Micropor. Mesopor. Mater. 257 (2018) 135-146. [9] S. Cimino, L. Lisi, A. Erto, F. A. Deorsola, G. de Falco, F. Montagnaro, M. Balsamo, Micropor. Mesopor. Mater. 295 (2020) 109949.
Catalysts and sorbents for environmental and energetic applications at CNR-STEMS
L Lisi
2022
Abstract
The development of materials at CNR-STEMS is mostly devoted to process intensification in the context of sustainability, in particular the low carbon technologies and the emissions control. Materials are designed at nano-scale level suitably tuning the properties through morphological, physico-chemical and functional characterization. The development of the catalyst/sorbent spans from the nano-scale up to process modelling and pilot testing according to an engineered multi-scale approach. The new materials are suitably designed with chemical and physical properties and functionalities tailored for specific applications. Among the main applications there are: Power to Gas, thermochemical cycles (chemical looping combustion/reforming/methanation, H2O/CO2 thermochemical splitting), purification of natural gas and bio-gas, exhaust after-treatment for diesel/gasoline engines, DeNOx, VOC abatement, CO2 capture, Hg/H2S removal, steam/dry/tri-reforming, poisoning tolerance and regeneration of catalysts, upgrading of by-products and wastes. Some examples of research activities focused on energetic and environmental applications at CNR-STEMS will be described along with the available techniques to characterize the materials and suitably address formulation and synthesis to optimize the performance. The first one is the development of Dual Function Materials (DFM) for chemical looping process of CO2 capture and hydrogenation to produce Synthetic Natural Gas (SNG). Catalysts with low Ru loading (< 1 % wt.) dispersed on Al2O3 spheres were promoted with variable amounts of Li (1-5 % wt.). The spontaneous formation of mixed lithium-aluminate phases effectively prevented the formation of highly stable carbonate species, peculiar of other alkali or alkaline-promoted DFMs, which are difficult to hydrogenate [1, 2]. The favourable synergism occurring at the nanoscale level between the Li-aluminate sorbent phase and the catalytic Ru sites enhanced the intrinsic activity of the DFMs that can guarantee high methane productivity and selectivity with low noble metal loadings. In addition to standard characterization techniques, results of in situ techniques (TG-MS, DRIFT), fundamental in the definition of the reaction mechanism, will be discussed. The role of textural and morphological properties of geopolymer based monoliths produced by additive manufacturing method (Direct Ink Writing), with the introduction of up to 60% by weight of pre-synthetized ZSM-5 into the extrusion ink, will be described to highlight the effect of hierarchical porosity in the NH3-SCR of NOx [3]. The catalyst, with a good mechanical resistance provided by the geopolymer, was exchanged with copper which was found preferentially located at the typical exchange sites in the zeolitic structure. These represent the active sites for the SCR reaction, whereas the formation of extra-framework CuO, detected for the pure geopolymer monolith, was minimized in the composite. The significant enhancement of the performance of the geopolymer-zeolite composites with respect to a pure self-sustained ZSM-5 foam monolith [4] appeared to benefit from their hierarchical structure given by the simultaneous presence of a macro/mesoporous (geopolymer) and a microporous (zeolite) phases. In particular, the results of porosimetric and TPD/TPR analyses and the effect on the SCR performance will be described. A special case focusing on the morphological aspects of the catalysts is represented by the issue of the contact between the catalytic CeO2 phase dispersed a SiC diesel particulate filter (DPF) and soot produced by diesel engine which are the two reactants of a solid-solid reaction. The oxidation temperature of soot can be significantly lowered provided that an effective contact between catalyst and soot is established. Nevertheless, solid-solid contact is not a trivial matter and suitable dimensions of catalysts particles and a proper dispersion are fundamental. The use of nanometric CeO2 particles as catalyst, suitably dispersed into the filter, resulted in excellent performance of the catalytic DPF assuring a tight contact with the soot particles without occluding the pores thus preserving the mechanical filtration properties of the DPF and activating soot oxidation at temperature close to that of the exhaust gases [5, 6]. Results of the porosimetric and SEM/EDS analysis to define the optimal amount and dispersion of CeO2 will be discussed. Finally, as last case, sorbents based on highly dispersed CuO-ZnO onto activated carbon for H2S removal from biogas at room temperature will be presented [7]. TPD/TPO experiments from partially and completely saturated sorbents allowed the speciation of adsorbed sulfur species, arising from the complexity of the surface reactions which, in turn, strongly depended on the Zn:Cu ratio, on the interactions of metal oxides with activated carbon and on the textural properties of the sorbent [8]. In particular, the additional catalytic role of copper, located into the carbon micropores, in the presence of H2O and O2, determining an increase in H2S capture rate, was analysed through the use of different techniques to investigate the extensive formation of different sulfur species in the exhaust sorbents under conditions close to the real ones [9]. [1] S. Cimino, F. Boccia, L. Lisi, J. CO2 Util. 37 (2020) 195-203. [2] S. Cimino, R. Russo, L. Lisi, Chem. Eng. J. 428 (2022) 131275. [3] E. M. Cepollaro, R. Botti, G. Franchin, L. Lisi, P. Colombo, S. Cimino, Catalysts 11 (2021) 1212. [4] N. Gargiulo, D. Caputo, G. Totarella, L. Lisi, S. Cimino, Catal. Today 304 (2018) 112-118. [5] V. Di Sarli, G.Landi, L. Lisi, A. Saliva, A. DI Benedetto, Appl. Catal. B 197 (2016) 116-124. [6] V. Di Sarli, G.Landi, L. Lisi, A. DI Benedetto, AIChE J. 63 (2017) 3442-3449. [7] M. Balsamo, S. Cimino, G. de Falco, A. Erto, L. Lisi, Chem. Eng. J. 304 (2016) 399-407. [8] G. de Falco, F. Montagnaro, M. Balsamo, A. Erto, F. A. Deorsola, L. Lisi, S. Cimino, Micropor. Mesopor. Mater. 257 (2018) 135-146. [9] S. Cimino, L. Lisi, A. Erto, F. A. Deorsola, G. de Falco, F. Montagnaro, M. Balsamo, Micropor. Mesopor. Mater. 295 (2020) 109949.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
