L. García

CO2 as a gasifying agent for gas production from pine sawdust at low temperatures using a Ni/Al coprecipitated catalyst

Catalytic CO2 gasification of pine sawdust has been carried out at a relatively low temperature, 700°C, and at atmospheric pressure. The Ni/Al catalyst used was prepared by coprecipitation and calcined at 750°C for 3 h. The influence of the catalyst weight/biomass flow rate (W/mb) ratio on product distribution and gas composition was analyzed. Using a CO2/biomass ratio of around 1, the increase of the W/mb ratio increases H2 and CO yields while CH4 and C2 yields decrease. Deactivation of the catalyst was also observed under the experimental conditions employed. The influence of the W/mb ratio on the initial gas yields has been also analyzed. For W/mb ratios ≥0.3 h, no significant modifications are observed on the initial yields of different gases, and it is confirmed that under these conditions the initial gas composition is close to that for thermodynamic equilibrium. The influence of the reaction atmosphere on gas yields has also been carried out, analyzing the results obtained in pyrolysis, steam gasification and CO2 gasification.

The effect of lanthanum on Ni–Al catalyst for catalytic steam gasification of pine sawdust

The influence has been studied of the addition of lanthanum to coprecipitated Ni–Al catalysts used in the catalytic steam gasification of biomass. The experimental work was carried out at a relatively low temperature, 700 °C, and at atmospheric pressure. Three Ni–Al–La catalysts were prepared, the Ni content being the same in all cases but with varying amounts of La and Al. The evolution of gas yields over time was analysed and the results obtained with the modified catalysts compared with those corresponding to the Ni–Al catalyst. The addition of lanthanum to the Ni–Al catalyst resulted in an increase in CO, CO2, CH4, C2 and total gas yields, while the H2 yield remained almost unchanged. This demonstrates that when the Ni–Al catalyst includes lanthanum in its formulation, a higher transformation of the carbon contained in the biomass to valuable gases takes place and, consequently, less coke is formed over the catalyst. These effects were also analysed in relation with another reaction, CO2 reforming of CH4, where similar trends were noted.

Catalytic pyrolysis of biomass: influence of the catalyst pretreatment on gas yields

Abstract This experimental study of biomass catalytic pyrolysis at low temperatures (650 and 700°C) was carried out in an installation based on the Waterloo Fast Pyrolysis Process (WFPP) technology, with a Ni/Al coprecipitated catalyst introduced into the reaction bed where the thermochemical decomposition of biomass took place. The influence of the calcination temperature (750–850°C) and the activation conditions (hydrogen flow rate) of the catalyst were analyzed. The calcination temperature significantly influences the properties and performance of the catalyst. For the two reaction temperatures, 650 and 700°C, and with the catalyst calcined at 850°C, higher H 2 and CO yields were obtained with the reduced catalyst (flow rate 3080 cm 3 (STP)/min; WHSV=0.826 h −1 ) than without reduction. However, the catalyst calcined at 750°C without reduction showed a good performance at the reaction temperature of 700°C. Considering the characterization and experimental results, it can be deduced that the catalyst calcined at 750°C is reduced by the reaction atmosphere forming a stable active phase, whereas for the catalyst calcined at 850°C more severe reduction conditions are necessary.

Bioenergy II: Hydrogen Production by Aqueous-Phase Reforming

The present work is focused on the aqueous-phase reforming of ethylene glycol at 500 K. The influence of the system pressure (27 to 36 bar) and the catalyst weight/ethylene glycol flow rate ratio has been studied using a Pt/Al2O3 research catalyst. A comparison of the latter with a Ni/Al coprecipitated catalyst showed a significant influence on hydrogen and alkane selectivities.

Assessment of Coprecipitated Nickel-Alumina Catalysts for Pyrolysis of Biomass

Various catalysts are being developed and tested for the pyrolysis of biomass using the Waterloo Fast Pyrolysis Process (WFPP) technology. The present paper describes pyrolysis tests with wood in a continuous bench scale fluidized bed reactor at 650 °C and at short gas contact times. A crystalline nickel aluminate catalyst of spinel structure prepared by coprecipitation is used.

Black Liquor Pyrolysis and Char Reactivity

Black liquor is the wastewater from the cooking of wood or straw in the production of pulp and paper. Nowadays new processes are being investigated as alternatives to the traditional recovery boiler used for black liquor treatment. One of the processes which appears to be more promising is gasification, for which further research is needed for its full industrial implementation.

Liquid and Gas Biofuels from the Catalytic Re-forming of Pyrolysis Bio-Oil in Supercritical Water: Effects of Operating Conditions on the Process

This work analyses the influence of temperature (310–450 °C), pressure (200–260 bar), catalyst/bio-oil mass ratio (0–0.25 g catalyst/g bio-oil) and reaction time (0–60 min) during the re-forming in sub- and supercritical water of a bio-oil obtained from the fast pyrolysis of pinewood. The original liquid has a 39 wt.% of water and the following elemental composition in dry basis: 54 wt.% C, 3.3 wt.% H, 41.3 wt.% O, 0.8 wt.% N and 0.6 wt.% S. The upgrading experiments were carried out in a batch microbomb reactor employing a co-precipitated Ni–Co/Al–Mg catalyst. Statistical analysis of the re-forming results indicates that the operating conditions and the water regime (sub-/supercritical) have a significant influence on the process. Specifically, the yields to upgraded bio-oil (liquid), gas and solid vary in ranges of 5–90 %, 7–91 % and 3–31 % respectively. The gas phase, having a medium-high lower heating value (2–17 MJ/STP m3), is made up of a mixture of H2 (9–31 vol.%), CO2 (41–84 vol.%), CO (1–22 vol.%) and CH4 (1–45 vol.%). Depending on the operating conditions, the amount of C, H and O (wt.%) in the upgraded bio-oil varies in ranges of 48–74, 4–9 and 13–48 respectively. This represents an increase of up to 42 and 152 % in the proportions of C and H respectively, as well as a decrease of up to 69 % in the proportion of O. The higher heating value (HHV) of the treated bio-oil varies from 20 to 32 MJ/kg, which corresponds to an increase of up to 68 % with respect to the HHV of the original bio-oil.

Pyrolysis Bio-Oil Upgrading to Renewable Liquid Fuels by Catalytic Hydrocracking: Effect of Operating Conditions on the Process

This work analyses the influence of operating conditions during the catalytic hydrocracking of a bio-oil obtained from the fast pyrolysis of pinewood. The original liquid has a 39 wt.% of water and the following elemental composition in dry basis: 54 wt.% C, 3.3 wt.% H, 41.3 wt.% O, 0.8 wt.% N and 0.6 wt.% S.

Hydrogen Production from Catalytic Biomass Pyrolysis

An overview is presented on different catalytic routes for producing hydrogen from biomass via pyrolysis processes. Fundamentals of biomass pyrolysis along with general aspects related to the types of processes and catalysts are discussed. Processes that allow hydrogen production in this field have been divided into single-step and multi-step processes. These processes are reviewed in this chapter, showing the state of the art. In both strategies, a hydrogen-rich product gas is obtained which, conveniently conditioned and purified, may serve for various purposes.