M.J. Lázaro

Behaviour of different industrial waste oils in a pyrolysis process: metals distribution and valuable products

Abstract In the present paper, the results obtained in the pyrolysis of four industrial waste oils (automotive, hydraulic, machine and cutting oil) are shown. The pyrolysis has been carried out at atmospheric pressure and 600°C. The continuous injection of the samples was into the bottom part of the reactor using a pump. Liquid and gases fractions have been analysed, organic products by gas chromatography and metals concentration by Graphite Furnace Atomic Absorption Spectrometry (GFAAS). The gases obtained are mainly formed by methane and light olefins, C 2 – C 4 , and the liquids contain an aromatic fraction of high industrial value. The behaviour of metals was also very different from one oil to another. Lead was the most affected metal in all of them, with a decrease ratio (concentration before and after the pyrolysis) from 165 for machine oil to 32 for the hydraulic oil. Pb, Cr, Cu, Ni, Pb and V were identified and quantified in each fraction. The results show that the automotive and machine waste oils are the better ones concerning the liquid yields. However, the hydraulic and cutting oils show a high conversion to gas products. The relationship between the type of waste oil and the products obtained is discussed.

Synergetic effects in the co-pyrolysis of coal and petroleum residues: influences of coal mineral matter and petroleum residue mass ratio

Abstract The influence of coal and mineral matter nature, and the coal/petroleum residue weight ratio, on the synergetic effects observed when coal and petroleum residues are copyrolysed has been studied. Two coals (Samca, a subbituminous one, Figaredo, a bituminous one, and a demineralised Samca coal) and three-coal/petroleum residue ratio (70/30, 50/50 and 40/60) have been used. Pyrolysis runs were carried out at analytical scale, by pyrolysis-gas chromatography in a pyroprobe 1000 CDS at 900°C and at atmospheric pressure. Synergetic effect on the yield of the main pyrolysis products has been evaluated and discussed with attention focused on valuable feedstock petrochemical products such as light olefines and light aromatic compounds. It is concluded that the intensity of the synergetic effects depends on the coal nature. In the Samca coal with petroleum residue mixtures, the increase in petroleum residue ratio promotes the production of light olefins, disfavouring the production of aromatic compounds. In contrast, for the Figaredo coal, petroleum residue ratio has not a significant influence on the synergetic effects. Coal mineral matter seems to play a negative effect on synergetic effects since an increasing of synergetic effect in light olefins and BTX has been observed after demineralisation of the Samca coal. However, this effect could be attributed to both, the removing of the mineral matter and the changes produced in the porous structure of coal by the acid treatment.

Co-pyrolysis of a mineral waste oil/coal slurry in a continuous-mode fluidized bed reactor

Abstract The main objective of this paper is to study the co-pyrolysis of a Spanish low rank coal and a mineral waste oil (MWO) slurry. The goal is to process the coal, handling it as a slurry by using a waste as the fluid component of the slurry in a continuous-mode preparative scale pyrolysis unit. It has been shown that a MWO/coal slurry can be successfully processed in a pulsed feeding fluidized bed reactor. Liquid and gases fractions have been analysed for organic products and metals. High yields of valuable light olefins such as ethylene and propylene and light aromatics as benzene, toluene, xylene and naphthalene derivatives have been obtained. The results show that both quantity and quality of gases and liquids obtained are significantly improved in relation to those obtained from coal. Special attention has been paid to the fate of metals contained in the MWO/coal slurries and their distribution into the co-pyrolysis products. In particular, the distribution of six metals (Cd, Ni, Pb, Cu, Cr, V) has been studied. The data show that metals under study are totally or partially trapped in the char formed during co-pyrolysis. This way the contents of Pb, Cu, V and Ni in the pyrolysis products leaving the reactor is substantially lower than in the feeding what will facilitate the obtention of valuable products.

Hydrogen production by catalytic decomposition of methane using a Fe-based catalyst in a fluidized bed reactor

Catalytic decomposition of methane using a Fe-based catalyst for hydrogen production has been studied in this work. A Fe/Al2O3 catalyst previously developed by our research group has been tested in a fluidized bed reactor (FBR). A parametric study of the effects of some process variables, including reaction temperature and space velocity, is undertaken. The operating conditions strongly affect the catalyst performance. Methane conversion was increased by increasing the temperature and lowering the space velocity. Using temperatures between 700 and 900 °C and space velocities between 3 and 6 LN/gcat.h), a methane conversion in the range of 25%–40% for the gas exiting the reactor could be obtained during a 6 h run. In addition, carbon was deposited in the form of nanofilaments (chain like nanofibers and multiwall nanotubes) with similar properties to those obtained in a fixed bed reactor.

Low-cost sorbents for demetalisation of waste oils via pyrolysis

Abstract The behaviour of several solid sorbents during the pyrolysis process of industrial waste oils in a bench-scale pyrolysis unit is studied. The concentrations of V, Ni, Pb, Cd, Cu and Cr in the waste oils and in the original sorbents as well as that obtained in the final valuable product liquid fraction are measured. Limestone, commercial active char, Samca char, activated Samca char and sepiolite were the solid sorbents used. 100% of the lead from the waste oils can be retained on limestone. The behaviour of both metals and sorbents and the influence of specific surface area as well as chemical nature of metals and sorbents are discussed. Final liquid fractions resulted in valuable industrial products.

Nitrogen Doped and Functionalized Carbon Materials as Supports for Catalysts in Electro-Oxidation of Methanol

The objective of this work is to study the behavior of Nitrogen-doped carbons as supports of catalysts for the electro-oxidation of methanol. Two carbon materials have been considered: a) carbon xerogels (CXG), highly mesoporous, whose porosity and pore size distribution are easily performed during the synthesis method; b) carbon nanofibers (CNF), which have a high electrical conductivity, good behavior in high temperature conditions and resistance to acid/basic media. Meanwhile, a commercial carbon black (Vulcan XC72R) which is commonly used in manufacturing of electrocatalysts fuel cells was used for comparison. Nitrogen was introduced into the CXG during the synthesis process, what is commonly referred as doping, by including melamine as a reactant. In contrast, N-groups were created over CNF by post-treatment with: ammonia (25%), urea (98%), melamine (99%) and ethylenediamine (99.5%), with a carbon: nitrogen molar ratio 1:0.6. N-containing carbon materials were characterized by elemental analysis, nitrogen adsorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), SEM-EDX and TEM to determinate the amount and forms of nitrogen introduced. Pt-catalysts were prepared by the microemulsion method. The influence of the nitrogen doping and functionalization on the catalytic behavior in the electrochemical oxidation of methanol was evaluated by different physicochemical and electrochemical analysis.

Distribution of the activation energies for the thermal decomposition of organic and pyritic sulphur in coal

The activation energies for the thermal cracking of the organic sulphur of several coals ranking from lignite to subbituminous have been calculated. Likewise, the activation energies for the thermal decomposition of the pyrite associated with different density fractions obtained from a subbituminous coal by sink-float analysis have been determined. The model of multiple, parallel, independent (MPI) first order reaction has been assumed for the thermal cracking. The kinetic equations associated with a Gaussian distribution of the activation energies (DAE) have been used for calculating the average activation energy, E 0 , and the standard distribution, σ. The results obtained show small differences between the parameters calculated for the cracking of the organic sulphur contained in the different coals tested