CONICET | Buscador de Institutos y Recursos Humanos

The production of fuels and raw materials for the chemical industry from bio-oils obtained by the pyrolysis of residual lignocellulosic biomass is an attractive option which deserves sounder research. Particularly, co-processing bio-oils together with conventional feedstocks in existing refining processes, that is, taking advantage of present infrastructure, could be feasible, without the need for extra capital costs. The catalytic cracking of hydrocarbons (FCC) and hydrotreating processes are certainly possible acceptors for bio-oils, since their catalysts and process conditions are proper to convert oxygenated compounds in bio-oils into high value products. However, bio-oils could contribute significantly to coke yields, a fact which could be alleviated if the boil-oils are previously upgraded by means, for example, of a thermal process. Anyway, some of the present FCC technologies permit processing residual hydrocarbons feedstocks with a high coke forming potential, without a negative impact on process performance. In order to know about reaction mechanisms and products in the conversion of bio-oils over FCC catalysts, the catalytic cracking of model compounds representing the various chemical types which can be found in bio-oils, of a synthetic bio-oil assembled with those model compounds and of crude and upgraded bio-oil from the pyrolysis of pine sawdust was studied under FCC conditions in a MAT-type reactor. The crude and upgraded bio-oil were also studied in a CREC Riser Simulator reactor. It was observed that phenolic and aromatic ethers as well as some cyclic ketones and furans produce significant amounts of coke (up to 16 %wt.). Starting from all the chemical types it was possible to produce high value hydrocarbons, particularly light olefins and hydrocarbons in the gasoline range. Moreover, the thermal upgrading of actual bio-oil decreased up to 30 % its potential to form coke and improved its processability, thus impacting positively on the co-processing with fossil feedstocks. During co-processing with vacuum gas oil (VGO) under typical FCC conditions in the CREC Riser Simulator reactor, it was observed that for high proportions of oxygenated compounds (up to 20 %), the yield of gasoline decreased and the yield of light olefins increased, but coke yield was lower than that from pure VGO due to the dilution effect from water in the bio-oil. Following more realistic conditions (addition of 5% of bio-oil to the VGO), the distribution of products was not changed significantly.

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