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Bio-oils obtained by pyrolysis of lignocellulose feedstocks must be upgraded to reduce the oxygen content, improving their quality as biofuels. Catalytic hydrotreatment has been proposed to reduce the oxygen content of biofuels and meet the standard requirements. Acetophenone is interesting as a model compound for the study of hydrodeoxygenation of pyrolysis bio-oils, which contain aromatic ketones. In this work, acetophenone gas-phase hydrodeoxygenation over precious metal (Pt, Pd, Ru, and Rh) supported catalysts has been studied in a fixed-bed reactor (space time, W/F = 0.75−1.0 kg cat s mol tot −1 ). The influence of the catalyst active phase and operating conditions (pressure of 0.5−1.5 MPa and temperature of 275− 375 °C) on the catalyst stability and activity and product distribution was studied. For the optimum pressure (1.0 MPa) and 275 and 375 °C, a reaction kinetic model based on the reaction scheme has been proposed and fitted to the experimental data obtained at different space velocities (W/F = 0−1.5 kg cat s mol tot −1 ).

Previous work carried out for the last eight years resulted in the proposal of a complete system of dimensionless groups in order to represent the performance of dierent kinematic Stirling engine con®gurations. When looking for experimental support for the proposed model, some differences between the performances of several prototypes were observed. In this paper an equation is introduced to be applied to all known kinematic engines and to their whole range of performance. The coecients appearing in this equation can be computed from temperature and geometrical dimensionless ratios and from experimental measurements at the maximum indicated power operating point. The meaning of those coecients is interpreted and their usefulness to provide an engine performance overview is shown. The quasi-static simulation and the characteristic Mach number at the maximum indicated power operating point appear to be interesting criteria in order to evaluate the performance of prototypes. NOTATION a, b dimensionless coecients of the friction factor A xx cross-sectional area (m 2 ) C f friction factor L length (m) n s engine speed (r/s) N B Beale number N MA characteristic Mach number n s V 1a3 E a RT C p N p characteristic pressure number p m V 1a3 E a " RT C p N SG N MA N re local instantaneous Reynolds number N RE characteristic Reynolds number p m V 2a3 E n s a "RT C N SG N 2 MA N SG characteristic Stirling number p m a"n s N TCR characteristic regenerator thermal capacity number & r c r T C ap m N W West number N characteristic regenerator thermal diusivity number r aV 1a3 E RT C p p m mean pressure (Pa) P B brake power (W) P ind indicated power (W) r crank radius (m) r hx hydraulic radius (m) R speci®c gas constant (J/kg K) T temperature (K) u local instantaneous¯uid velocity (m/s) V swept volume (m 3 ) V dx dead volume (m 3 ), Y 1 dimensionless coecients of the mechanical losses of the indicated power r regenerator material thermal diusivity (m 2 /s) xx dimensionless cross-sectional area parameter A xx raV E adiabatic coecient 1 , F F F , n angles and other dimensionless parameters of the drive mechanism, normalized by the crank radius dimensionless indicated power P ind ap m V E n s B dimensionless brake power P B ap m V E n s mec dimensionless mechanical losses of the indicated power À B ÁP ind ap m V E n s mec mechanical eciency B a swept volume ratio V C aV E ! dimensionless parameter as de®ned in text ! hx dimensionless hydraulic radius parameter r hx ar heThe MS was

The aim of this work is to study the gas-phase hydrodeoxygenation (HDO) of bio-oil-related platform molecules over precious metal catalysts (Pt and Pd on alumina) at moderate temperature (325 °C) and low pressure (0.5 MPa). Bio-oils consist of a complex mixture of compounds, many of which are aromatic oxygenates, and have been modeled here by four model compounds with different oxygenated functional groups: benzaldehyde (aldehyde), benzyl alcohol (alcohol), phenyl acetate (ester), and anisole (ether). First, the stability and activity of the catalysts in the HDO of the different compounds have been studied in an isothermal fixed-bed reactor. The performance of the Pt catalyst is better than that of the corresponding Pd catalyst (highest activity and selectivity). The compound more refractory to HDO over Pt was benzyl alcohol. Both catalysts suffer from strong deactivation at the beginning of the tests, mainly by the formation of carbonaceous deposits. The deactivation is particularly strong for the HDO of benzyl alcohol over the Pd catalyst. Second, a kinetic study has been carried out varying the space time (0−1 (kg cat s)/mol). Kinetic models, based on reaction networks derived from the product distributions, have been proposed, and the kinetic constant fit to the experimental data by least-squares regression.

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