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Deactivation of Ni/La2O3–αAl2O3 catalyst in ethanol steam reforming (ESR) was studied in order to establish the optimal conditions for maximizing H2 production and achieving steady behavior. The ESR reactions were conducted in a fluidized bed reactor under the following operating conditions: 500–650 °C; space-time up to 0.35 gcatalyst h/gEtOH; and steam/ethanol (S/E) molar ratio in the feed, 3–9. The features of the deactivated catalysts and the nature and morphology of the coke deposited were analyzed by temperature-programmed oxidation, X-ray diffraction, scanning electron microscopy, and Raman spectroscopy. Catalyst deactivation was solely caused by coke deposition, especially by encapsulating coke, with acetaldehyde, ethylene, and ethanol being the main precursors, whose concentration was high for lower values of space-time. Conversely, the filamentous coke formed from CH4 and CO (with their highest concentration for intermediate values of space-time) had a much lower impact on deactivation. Owing to the effect of space-time on the extent of reactions leading to the formation of coke precursors, the Ni/La2O3–αAl2O3 catalyst stability was enhanced by increasing space-time. The increase in temperature and S/E ratio was also beneficial since both variables promoted coke gasification. Consequently, a steady H2 yield throughout 200 h reaction was attained at 600 °C, a space-time of 0.35 gcatalyst h/gEtOH, and S/E > 3.

The effect that operating conditions (temperature, steam/carbon molar ratio, and space-velocity) have on the steam reforming of raw bio-oil has been studied in a two-step reaction unit. In the first step (operated at 500 °C), a carbonaceous solid (pyrolytic lignin) deposits by repolymerization of certain bio-oil components, and the remaining volatiles are reformed in the second step (fluidized bed reactor) on a Ni/La2O3–αAl2O3 catalyst. Under suitable reforming conditions (700 °C, S/C = 9, space-velocity = 8000 h–1), the yields of H2 and CO were 95% and 6%, respectively. Catalyst deactivation was very low, whereby the H2 yield decreased by only 2% over 100 min of reaction. By using dolomite as adsorbent in the reforming reactor, CO2 was effectively captured, and the raw bio-oil was reformed at 600 °C without adding water (S/C = 1.1), thus avoiding its vaporization cost. The yields of H2 and CO were 80–82% and 1%, respectively, for a space-velocity (GC1HSV) of 7000 h–1 and catalyst/dolomite ratio of 0.25, although a high yield of CH4 (7%) was obtained due to the cracking capacity of the dolomite. The coke content on the catalyst was high (7.7 wt % in 2 h) because of the limited gasification of coke precursors under the operating conditions (low temperature and low S/C ratio) used in the process with CO2 capture.

The effect of O 2 content in the oxidative steam reforming (OSR) of raw bio-oil has been studied, and the kinetic behavior, particularly deactivation, has been compared between two catalysts (Ni/La 2 O 3 -αAl 2 O 3 and Rh/CeO 2 -ZrO 2 ). The experiments have been carried out in an apparatus with two steps in series: (1) thermal treatment (at 500 °C, for the controlled deposition of pyrolytic lignin) and (2) catalytic in-line reforming in a fluidized bed. The reaction conditions have been as follows: oxygen/carbon ratio (O/C), 0, 0.17, 0.34, and 0.67; 700 °C; steam/carbon ratio (S/C), 6; space time, 0.3 g catalyst h/g bio-oil (for Ni/ La 2 O 3 -αAl 2 O 3 ) and 0.15 g catalyst h/g bio-oil (for Rh/CeO 2 -ZrO 2 ); time on stream, 4 h. The content and morphology of the coke deposited on the catalysts has been determined by temperature-programmed oxidation (TPO), and the deterioration of the metallic properties of the catalysts by temperature-programmed reduction (TPR) and X-ray diffraction (XRD). The results (biooil conversion, product yield and their evolution with time on stream) show that for Rh/CeO 2 -ZrO 2 catalyst the decrease in coke deposition as O/C ratio is increased involves attenuation of catalyst deactivation. Consequently, this catalyst is stable after 24 h operation for high O/C ratios, thus keeping constant the activity for reforming reactions and the WGS reaction, with a high yield of H 2 and low yields of CO, CH 4 , and hydrocarbons. However, for the Ni/La 2 O 3 -αAl 2 O 3 catalyst of lower activity than the Rh/ CeO 2 -ZrO 2 , the decrease in coke content as O/C ratio is increased does not involve a noticeable attenuation in catalyst deactivation, which is due to Ni sintering.

Recent advances in lignocellulosic biomass valorization for producing fuels and commodities (olefins and BTX aromatics) are gathered in this paper, with a focus on the conversion of bio-oil (produced by fast pyrolysis of biomass). The main valorization routes are: (i) conditioning of bio-oil (by esterification, aldol condensation, ketonization, in situ cracking, and mild hydrodeoxygenation) for its use as a fuel or stable raw material for further catalytic processing; (ii) production of fuels by deep hydrodeoxygenation; (iii) ex situ catalytic cracking (in line) of the volatiles produced in biomass pyrolysis, aimed at the selective production of olefins and aromatics; (iv) cracking of raw bio-oil in units designed with specific objectives concerning selectivity; and (v) processing in fluidized bed catalytic cracking (FCC) units. This review deals with the technological evolution of these routes, in terms of catalysts, reaction conditions, reactors, and product yields. A study has been carried out on the current state-of-knowledge of the technological capacity, advantages and disadvantages of the different routes, as well as on the prospects for the implementation of each route within the scope of the Sustainable Refinery. /jctb 2 -C 4 olefins 147 a % Relative area: Percentage of total peak area detected by GC/MS semi-quantitative analysis.

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