Abstract
This study reports a new fluidizable Ni catalyst supported on La2O3 modified gamma-Al2O3. The 20% Ni/5% La2O3-gamma Al2O3 catalyst is prepared using a specially designed multistep incipient wetness technique and direct reduction of metal nitrate precursors. Steam gasification of glucose (a biomass surrogate), is developed in a CREC Riser Simulator using the new fluidizable catalyst. Experiments are performed at different steam/biomass ratios, temperatures and reaction times. Catalytic gasification runs confirm the high performance of the Ni/La2O3-gamma Al2O3 in terms of reforming activity, and reduced coke formation. Furthermore, observed gasification products (Hz, CO, CO2, and CH4) are in agreement with thermodynamics, with product yields approaching chemical equilibrium as the reaction time is increased. Furthermore, the value of the Ni/La2O3-gamma Al2O3 catalyst is demonstrated while comparing its improved performance with respect to the one of other prepared catalysts: (i) an unpromoted NihiAl(2)O(3) and (ii) a Ni/La2O3-gamma Al2O3 prepared via metal precursor calcination. Prepared catalysts are also characterized using BET surface area analysis, TPR, TPO, Hz-pulse chemisorption, pyridine FTIR, CO2 and NH3 TPD. It is shown that the addition of lanthanum oxides reduces surface area losses, increasing the thermal stability of gamma-Al2O3. La2O3 also improves reducibility and dispersion of the active phase by decreasing nickel-aluminate formation. Pyridine FTIR confirms the absence of Brensted acid sites in gamma-Al2O3, with La2O3 reducing Lewis acidity. Multiple TPO and TPR experiments also show that the prepared catalyst remains stable under repeated oxidation and reduction cycles. As a result, it is proven that the enhanced gasification activity of the Ni/La2O3-gamma Al2O3 fluidizable catalyst of the present study is in line with their various and favorable structural properties (available Ni surface area and basicity/acidity ratio) modifications. (C) 2014 Elsevier B.V. All rights reserved.