SÍNTESIS DE SULFUROS NANOESTRUCTURADOS BIMETALICOS DEL TIPO NiMoS x C y , EN PRESENCIA DE AGENTES DIRECTORES DE ESTRUCTURA Y SU ACTIVIDAD EN REACCIONES DE HDS ( NANOSTRUCTURED SULFIDE SYNTHESIS TYPE BIMETALLIC NiMoS x C y IN THE PRENSENCE OF STRUCTURE DIRECTING AGENTS AND THEIR ACTIVITY IN HDS )

Abstract

Con la vista puesta en la reduccion de azufre en diesel, fueron sintetizados catalizadores bimetalicos NiMo novedosos, soportados y en bulk, usando agentes directores de estructura. Dichos materiales fueron modificados durante el protocolo de calcinacion, con el fin de obtener sistemas nanoestructurados. Todos los catalizadores fueron caracterizados usando diversas tecnicas analisis elemental, analisis quimico, microscopia de transmision, microscopia de barrido, isotermas adsorcion-desorcion de N 2 , difraccion de rayos-X, espectroscopia de fotoelectrones, dinamic light scatering y RAMAN. La presencia de CTAB, como agente director de estructura, permitio obtener materiales nanoestructurados, con tamanos de particulas entre 5 y 50 nm. Los materiales producidos son s NiMoS x C y de alta area superficial, que cuando son sujetos a una oxidacion “suave” permite obtener nanoestructuras con un minimo de sinterizacion. La actividad catalitica de todos los sustratos en la reaccion de HDS, fue determinada en un reactor de lecho fijo a tres temperaturas 320, 360 y 400 °C, 40 bar de presion de H 2 , WHSV = 39 h -1 y 3h de reaccion. El alimento para la reaccion de HDS se preparo considerando el “efecto matriz”, de manera que estaba constituido por parafinas (60%), olefinas (30%), hidrocarburos aromaticos (10%) y sulfurados (470 ppm). Estos ultimos constituidos por sulfuros muy refractarios presentes en el diesel tal como DBT (100 ppm) y 4,6-DMDBT (100 ppm).Todos los materiales sintetizados presentaron actividad en la reaccion de HDS (400 °C, 3h), alcanzandose altas conversiones, pero favoreciendo al sustrato menos refractario DBT.

With a view to reducing the sulfur content in diesel fuels, were synthesized bimetallic catalysts novel NiMo catalysts, supported and unsupported, using structure-directing agents. The above mentioned materials were modified during the protocol of calcinations, in order to obtain nanostructured systems. All catalysts were characterized using several techniques CHNS-O, ICP-OES, TEM, SEM, EDX, N 2 adsorption–desorption isotherms (BET), XRD, XPS, DLS and RAMAN. The presences of CTAB, as structure-directing agents, lead to nanostructured materials, with size of particle between 5 y 50 nm. The produced materials are hybrid NiMoS x C y the high surface area, which when they are subject to a “soft” oxydation leads to obtain nanostructured with minimum of sinterization. The catalytic activity of all substrates in HDS`s reaction, was determined in a flow fixed bed reactor at three temperatures 320, 360 y 400 °C, 40 bar of pressures of H 2 , WHSV = 39 h -1 and 3h for reaction time. The feedstock for HDS´s reaction was prepared considering “the matrix effect”, so that is was constituted by paraffin’s (60%), olefins (30%), and aromatic hydrocarbons (10%), and sulfur compounds (470 ppm). These last compounds constituted by very refractory species present in the fuel diesel as DBT (100 ppm) and 4,6-DMDBT (100 ppm). All the synthesized materials presented activity in the HDS reaction of (400 °C, 3h), conversions being reaching high conversions, favoring the least refractory DBT substrates.