[en] This thesis is devoted to the optimization of the biomass pyrolysis process for the simultaneous production of bioreducing agents and high value gases. The thesis is part of the existing collaborative research work between the Befesa Steel R&D S.L. Company and the Chemical and Environmental Engineering Department of the Faculty of Engineering of Bilbao. This company was interested in developing the pyrolysis process at large scale to produce biocoke to be used as reducing agent in some of their industrial plants. In order to obtain pyrolysis solids useful as reducing agents in metallurgical processes, a slow pyrolysis process at high temperatures is required. In order to obtain high value gases, it is necessary to perform a second catalytic step for pyrolysis vapors upgrading by cracking and reforming so that tars are eliminated and H2/CO is maximized. Most of the pyrolysis experiments were carried out in an installation (swept with N2) composed of two reactors connected in series: a first non-stirred batch 3.5 L pyrolysis reactor, where 100 g of biomass are pyrolyzed, and a second 0.5 L tubular reactor, where the pyrolysis vapors upgrading takes place. The biomass samples used for this study were selected and provided by Befesa Steel R&D S.L. and consisted in two woody biomass samples: olives residues and eucalyptus. These biomass samples, as well as the pyrolysis solid, liquid and gases products, have been thoroughly characterized by means of the following techniques: proximate and ultimate analyses, constituents analysis, Py-GC/MS-FID characterization, higher heating value determination, GC/MS for the liquids and GC/TCD-FID for the gases. Four main types of studies have been carried out in this thesis work: (1) Study of the appropriate operating conditions for the simultaneous production of biocoke and high quality gases. With this aim, the effect of the heating rate (3-20 °C min-1) and temperature (600-750 °C) of the first pyrolysis reactor, as well as the influence of the temperature and catalysts of the second reactor were studied. (2) A comparative study of the effectiveness of different catalysts for the pyrolysis vapors upgrading (cracking and reforming). The following catalysts were tested: two homemade Ni/Al2O3 catalyst modified with CeO2 and ZrO2, two commercial zeolites (HY and HZSM5) doped with Ni and without doping, and a commercial catalyst (Katalco 57-4Q) also based on Ni and widely used in industry for steam reforming. (3) Evaluation of the suitability of biocokes as reducing agents for metallurgical applications. For this to be possible, surface area and porosity measurements, as well as reactivity tests of the biocokes with CO2, were carried out. The properties of the biocokes were compared with those of commercial reducing agents used in non-ferrous metallurgical processes (metallurgical coke, petroleum coke and anthracite) which were provided by Befesa Zinc Aser S.A. Company. Finally, as a consequence of the differences on the pyrolysis results obtained with different shipments of the olives samples, a comparative study of the influence of the type of biomass on the pyrolysis yields and products was carried out.

[eu] Doktorego Tesi honen helburua biomasa pirolisi prozesuren optimizazioa da, agente bioerreduzitzaileak eta balio erantsi handiko gasak ekoizteko. Tesi hau Befesa Steel R&D S.L. enpresa eta Bilboko Ingeniaritza Goi Eskola Teknikoko Ingeniaritza Kimikoa eta Ingurumenaren Ingeniaritza Sailak ikerketa arloan duten hartu-emanean kokatzen da. Enpresa honen helburuetako bat bere metal ez-burdinazko enpresetan erabiltzeko agente bioerreduzitzaileak (biokokea, sintesi gasa) ekoizteko prozesu bat garatzea da. Biokokeak (biomasa pirolisi-solidoak) metalurgia prozesuetan agente bioerreduzitzaile moduan erabilgarri izan daitezen, tenperatura altuko pirolisi motelak burutu behar dira. Balio erantsi handiko gasak (sintesi gasa) ekoizteko pirolisi-lurrunak balioztatu behar dira mundrunak ezabatuz eta H2 eta CO produkzioa igoz. Hau lortu asmoz, urrats katalitiko bat erabili behar da. Pirolisi esperimentu gehienak elkarren segidako bi erreaktoreez osatutako instalazio batean egin dira: lehenengoa 3.5 L-ko pirolisi-erreaktore bat da, bertan 100 g biomasa pirolizatzen direlarik; bigarrena pirolisi-lurrunak balioztatzen diren 0.5 L-ko hodi-erreaktore bat da. Tesi honetan erabilitako biomasa laginak Befesa Steel R&D S.L. enpresak aukeratutako bi biomasa lignozelulosiko ezberdin izan dira: olibondoen inausketa hondakinak eta eukaliptoak. Biomasa laginak, pirolisi-solidoak, -likidoak eta -gasak honako teknika hauen bidez karakterizatu dira: bat-bateko analisia, analisi elementala, osagaien analisia, Py-GC/MS-FID karakterizazioa, goi bero ahalmenaren determinazioa, GC/MS kromatografia pirolisi-likidoentzat eta GC/TCD-FID kromatografia pirolisi-gasentzat. Lau ildo ezberdin jarraitu dira doktorego tesi hau burutzerakoan: (1) Lehenengoa, biokoke eta balio erantsi handiko gasen ekoizpenerako prozesu baldintza egokienak ezartzea izan da. Horretarako, pirolisi-erreaktoreko berotze-abiadura (3-20 °C min-1) eta tenperaturaren (600-750 °C) efektua, eta hodi-erreaktoreko tenperatura eta katalizatzaileen eragina aztertu dira. (2) Bigarren ildoa, pirolisi-lurrunak balioztatzeko erabili diren katalizatzaileak konparatzean datza: CeO2 eta ZrO2-az moldaturiko bi Ni/Al2O3 katalizatzaile, nikelaz dopaturiko eta dopatu gabeko bi zeolita komertzial (HY eta HZSM5), eta nikelean oinarrituriko katalizatzaile komertziala (Katalco 57-4Q). Azken hau industria mailan ur lurrunaren bidezko erreformatuetan oso erabilia da. (3) Hirugarren ildoan aplikazio metalurgikoetan biokokeak agente erreduzitzaile bezala erabiltzeko duen gaitasuna aztertu da. Horretarako, biokokeen azalera eta porositate neurketak, eta erreaktibotasun-frogak egin dira. Biokokeen propietateak Befesa Zinc Aser S.A. enpresak ez-burdinazko prozesu metalurgikoetan erabiltzen dituen koke komertzialekin (koke metalurgikoa, petrolio-kokea eta antrazita) alderatu dira. (4) Azkenik, jasotako olibondoen lagin desberdinekin lortutako pirolisi emaitzetan aurkitutako ezberdintasunak direla eta, biomasa-motaren eragina aztertu da pirolisi-errendimendu eta produktuetan.