Wasteomics ⇒ a workflow to analyze complex reaction environments, waste, and realistic feeds conversions



Problem statement

In most heterogeneous catalytic processes, the reactive environment contains a mixture of reactants, intermediates, and products, and some adsorbed-trapped on the catalytic surface and elsewhere. Thus, most reacting environments in catalysis are complex, involve several phases (multiphase), and comprise unstable species or are challenging to analyze. To make things worse, some of these species have (auto-)catalytic or deactivating nature on the kinetics of the surrounding ones.

A typical practice in catalysis is using model molecules or surrogates to deepen into the mechanistic pathways, microkinetics, spectroscopy, etc. Conversely, analytical techniques keep evolving, becoming more precise but always targeting a specific fraction or type of species. That is to say, there is only one technique that solves all.

We aim to bridge the fundamental research performed in our group and outside using model molecules with a powerful analytical multi-technique approach to analyze the entire reaction media. The -omics fields inspire us to reflect on the collective characterization and quantification of pools of molecules that translate into the structure, function, and dynamics involved. We apply our approach to hydrocarbon transformations and green-sustainable feedstock (i.e., waste plastics, sewage sludge, biomass, algae, and seaweed). We develop multi-technique analytical protocols for the complete chemical molecular-level description of complex mixtures.

Goals

  • Analytical workflow ⇒ multi-analytical technique integration
  • Wasteometrics I ⇒ quantitative- and molecular-level analysis
  • Wasteometrics II ⇒ data mining and processing
  • Wasteomics ⇒ reaction networks and kinetic modeling

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Role of Oxygenates and Effect of Operating Conditions in the Deactivation of a Ni Supported Catalyst During the Steam Reforming of Bio-oil

by Ochoa, Aramburu, Valle, Resasco, Bilbao, Gayubo, Castaño
Green Chem. Year: 2017

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Abstract

This work investigates the correlation of the reaction conditions (temperature and steam-to-carbon ratio (S/C)) and the reaction medium composition with the deactivation behavior of a Ni/La2O3-αAl2O3 catalyst used in steam reforming of bio-oil, aiming at sustainable hydrogen production from lignocellulosic biomass. The reaction was performed in an in-line two-step system consisting of thermal treatment of bio-oil at 500 °C for retaining the thermal pyrolytic lignin and in-line steam reforming of the remaining oxygenates in a fluidized bed catalytic reactor. The reforming step was conducted at 550 and 700 °C and S/C ratios of 1.5 and 6. Fresh and deactivated catalyst samples were characterized using XRD, SEM, TEM, TPO, XPS, Raman and FTIR spectroscopy. The catalyst deactivation was mainly due to the amorphous and encapsulating coke deposition whose formation is attenuated when both the temperature and S/C ratio are increased. Although the highest catalyst stability is attained at 700 °C and/or an S/C ratio of 6, Ni sintering is noticeable under these conditions. The encapsulating coke is highly oxygenated, in contrast with the more aromatic and condensed nature of filamentous coke. Based on the correlation between the composition of the coke and the reaction medium, it was established that bio-oil oxygenates are the precursors of the encapsulating coke, particularly phenols and alcohols, whereas CO and CH4 are the possible precursors of the coke fraction made of filaments whose contribution to catalyst deactivation is hardly significant.

Keywords

REF W2C ANW MKM