• Energy Research

Abstract The use of renewable fuels is expected to grow in the coming years. A possibility to achieve this consists in blending renewable bio-oils with conventional refining streams to further process in existing refineries. A key aspect of bio-oils is the presence of oxygenate molecules in significant amounts. To shed light into the effect of these compounds on Fluid Catalytic Cracking (FCC), guaiacol was chosen as model compound. Data on the transformation of n-heptane in the presence of small quantities of guaiacol over pure HY and HZSM-5 zeolites at 450 °C is presented and compared to gasoil + guaiacol blend tests using an industrial FCC equilibrium catalyst (E-CAT) pure and blended with a commercial ZSM-5 additive. Guaiacol has a negative influence on both n-heptane and gasoil conversions, since it is responsible for an increase of the coke retained on the catalysts. In the presence of n-heptane and with pure zeolites, guaiacol increases the methane yield, in line with its transformation into phenol. With industrial FCC E-CAT, the presence of guaiacol increases gasoline yield and reduces coke yield, however, increases coke on catalyst. Detailed GC analysis of the liquid product shows presence of phenols in the gasoline cut, suggesting the partial conversion of guaiacol (with methane and water formation). HZSM-5 zeolite was more severely deactivated than HY zeolite in the n-heptane transformation, which agrees with the observed reduction of the ZSM-5 additive effect on the transformation of gasoil.

Abstract The present study aims at evaluating the efficiency of the HZSM-5 zeolite dealuminated with citric acid and modified with sulfated lanthanum oxide (SO42−/La2O3) as catalysts for the production of biodiesel via esterification. The effects of the treatments in the structural, textural and acid properties of produced catalysts were monitored by PXRD, adsorption/desorption of N2 and measurements of acidity by FTIR using pyridine and collidine as probe molecules. The catalysts were tested in the reaction of esterification using oleic acid and methanol as reactants. Different molar ratios (1:10, 1:20 and 1:45) and amounts of catalyst (2%, 5% and 10%) were tested and the conversion of oleic acid into methyl oleate analysed. Results show that the dealumination with citric acid and impregnation of SO42−/La2O3 over HZSM-5 produced catalysts more active for the conversion of oleic acid for the production of biodiesel, when compared to the parent HZSM-5 zeolite. The increase of external surface properties (acidity and area) was the main parameter influencing the activity of the catalysts for the considered reaction.

Abstract In this study, the efficiency of citric acid as dealumination agent was evaluated in the case of zeolite HZSM-5 by varying the experimental conditions, namely concentration (0.5, 1.0 and 2.0 mol L−1) and treatment temperature (60 and 80 °C). The effect of the CA treatment on structural, textural and acidity properties of the starting HZSM-5 material was monitored using XRD, N2 sorption and FTIR (pyridine and collidine) measurements. Heptane and methylcyclohexane cracking model reactions were used to evaluate the catalytic behavior of the modified materials, in terms of acid strength and active sites accessibility. The modified catalysts were tested in the esterification reaction, using oleic acid as reagent and different oleic acid/methanol molar ratios. All the results show the beneficial effect of the citric acid treatment on the physicochemical properties of the final materials, with an improvement of the external acidity, a crucial parameter for the reaction considered, i.e. the oleic acid esterification.

The envisaged upgrading of lignocellulosic biomass derived feedstocks (bio-oils) in dedicated units or by coprocessing in existing units of the refinery, to partially replace crude oil in the production of transportation fuels, is a topic that has been receiving much attention from both industry and academia in recent years. Regardless of lignocellulosic biomass origin, these feedstocks are complex mixtures of many oxygenated hydrocarbons. Therefore, their upgrading toward liquid fuels must include oxygen removal. So far, two main routes have been proposed, considering many studies at laboratory scale and others from industry: catalytic hydrotreatment (HDT), mainly hydrodeoxygenation (HDO), and catalytic cracking, technologies that are already present in today’s refineries configuration. HDO has been performed at high hydrogen pressure, using catalysts based on those typically applied in conventional hydrotreating, as well as a new type of supported noble metal and transition metal catalysts. Catalytic cr...