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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Related Publications

Identification of the coke deposited on an HZSM-5 zeolite catalyst during the sequenced pyrolysis-cracking of HDPE

by Ibanez, Artetxe, Lopez, Elordi, Bilbao, Olazar, Castaño
Appl. Catal. B: Environ. Year: 2014

Abstract

The pyrolysis–cracking of high-density polyethylene (HDPE) has been studied in two sequenced steps: (1) flash pyrolysis in a conical spouted bed reactor, and (2) catalytic cracking of the volatiles (waxes) in a fixed bed reactor containing a HZSM-5 zeolite catalyst, aiming light olefins as final products. The pyrolysis and cracking have been carried out isothermally at 500 °C, with a continuous feed of HDPE (1 g min−1) for up to 5 h (300 g of HDPE fed). We have correlated the catalytic deactivation by coke (carbonaceous deposits), in terms of amount and composition, with the profiles of gas composition along time on stream and space time. The amount and composition of coke in three axial positions of the catalytic bed have been elucidated using thermogravimetric (TG-TPO) and spectroscopic techniques (13C CP-MAS NMR, Raman, FTIR, FTIR-TPO-MS and FTIR-pyridine). Our results show that there are two pathways of coke formation: (i) initiation, during the first hour on stream and particularly in the inlet of the catalytic reactor; and (ii) steady coke formation, after the first hour on stream which is more severe in the last axial position of the catalytic reactor. The initiation step stems from the degradation of the waxes produced in the pyrolysis of HDPE and causes a dropping in the mesopore area of the catalyst. The steady coke formation step is caused by the condensation of light olefins and causes the degradation of the micropore area and the Brønsted acidity of the catalyst.

Keywords

FCC W2C ANW