Investigation Of Hydrogen Production By Catalytic Steam Reforming Of Bio-oil

Hydrogen is not only an important material for the chemical industry but also a clean fuel that can be used in fuel cells and internal combustion engines. One of the most promising technologies for hydrogen production is catalytic steam reforming of bio-oils produced by fast pyrolysis of biomass. Whole or part fractions of bio-oil can be converted to hydrogen via catalytic steam reforming followed by a CO shift conversion step. The present study investigated the fast pyrolysis of sawdust and steam reforming of the bio-oil.In this experiment, sawdust was used for producing bio-oil with a fluidized bed reactor in the fast pyrolysis process. The influences of several important parameters were examined such as reaction temperature, N₂ flow rate, sand volume and biomass feed rate. Physical properties of bio-oil from the biomass pyrolysis were analyzed, including density, acidity, moisture content and caloric value and elements of the bio-oil were analyzed, too. Moreover, the main volatile components of bio-oil were detected with GC-MS analysis technique, results of which were beneficial to the futther using of bio-oil. The best bio-oil yield was 65.9%, which was achieved at 500℃, N₂ flow rate 12 L·min^-1, sand volume 900 ml and biomass feed rate 1625 g·h^-1.Methanol and phenol using as model compounds in the steam reforming of bio-oil were carried out. The Ni-Ce/Olivine and Ni-Ce-Mg/Olivine catalysts were prepared by wet impregnation method using Ni-nitrate, Ce-nitrate and Mg-nitrate as the metal precursors, respectively and olivine as support. The steam reforming of model compounds were conducted at the operating conditions specified for each test. Reactor pressure drop, volumetric flow rate and total gas volume exiting the reactor and gas composition (via the GC) were determined. The experiments show that Ni/Olivine doped with CeO₂ catalyst was particularly effective catalytic activity for methanol. The addition of CeO₂ improves the stability of the catalyst and decreases coke formation. The 6%Ni-3%Ce/Olivine catalyst possessed the best catalytic activity at the temperature of 750°C, the water/carbon ratio of 1.5 and the space velocity of 11200 h^-1 . Under this condition, the conversion efficiency of methanol and H₂ production were 85.72% and 55.31% respectly. Steam reforming of model compound phenol was tested, and the Ni-based catalysts doped with CeO₂ and MgO showed good performance, too. Magnesium enhances steam adsorption capability and solid solutions of NiO/MgO stabilize nickel and prevent catalyst sintering, thus limiting coke formation. Commercial catalyst ICI46-1 that was developed for steam reforming of Naphtha was more efficient for hydrogen production from bio-oil than the investigated Ni-based catalysts mainly due to its higher water-gas shift activity.