Papers by Iacovos Vasalos
International Journal of Hydrogen Energy, 2006
A concept of sorption-enhanced steam reforming of bio-oil/biogas for electricity and heat generat... more A concept of sorption-enhanced steam reforming of bio-oil/biogas for electricity and heat generation by phosphoric acid fuel cells is investigated. The process is modeled using SIMSCI Pro II process simulator. Sorptive removal of the carbon dioxide from the reaction site results in low CO and CO2 concentrations (1%) in the reformate, as a result it can be used in the phosphoric acid fuel cell without any further fuel cleanup. High hydrogen concentration and calorific value of the reformate enable the operation of the fuel cell at a high-efficiency mode despite of the high carbon/hydrogen ratio of the bio-fuel. Addition of biogas to the reformer enables autothermal operation of the reformer, as well as significantly improves the efficiency of the process. The simulation shows that the overall efficiency of the proposed system is compatible with the efficiency of the system using “classical” steam reforming of the fuel. The process exhibits 6% lower electrical efficiency compared to the system utilizing natural gas, and 4.6% higher efficiency compared to a system using bio-oil as a fuel.
Industrial & Engineering Chemistry Research, 2009
ABSTRACT Hydrogen produced from renewable energy sources can present significant environmental be... more ABSTRACT Hydrogen produced from renewable energy sources can present significant environmental benefits as a means for clean power generation via fuel cells. The aqueous fraction of bio-oil can be used as a source for hydrogen production, if reformed in the presence of active catalytic materials. Recently, we introduced the concept of the spouted bed reactor for this particular process. The aim of the current work is to further investigate the suitability of the novel reactor. The effect of temperature, H2O/C ratio, space velocity, and heat treatment of support was investigated in the presence of Ni/Olivine catalysts. Runs were conducted with ethylene glycol and acetic acid as representative model compounds of the aqueous phase of bio-oil. The organics converted fully toward gases with high selectivity in hydrogen, while the known problem of coking was notably avoided. Ethylene glycol reforming seems to proceed primarily via decomposition followed by reforming of secondary products. Hydrogen yield during acetic acid reforming is higher under equivalent conditions. Tests using the aqueous phase of bio-oil proved more complicated due to the serious thermal instability of the feed. A new injection-cooling system was developed in order to achieve efficient feeding of bio-oil.
Industrial & Engineering Chemistry Research, 1989
Industrial & Engineering Chemistry Research, 2011
The production of synthetic transportation fuels from lignocellulosic biomass feedstocks through ... more The production of synthetic transportation fuels from lignocellulosic biomass feedstocks through a biomass-to-liquid (BTL) process based on Fischer−Tropsch (F−T) synthesis is today of increasingly importance. Depending on the operating conditions of the F−T process, heavy waxy hydrocarbons could be produced (waxes) with almost zero aromatics and sulfur. The purpose of this study is the investigation of a catalytic cracking process for the upgrading of these BTL waxes in order to produce high-quality biofuels. In this work, a F−T Wax with hydrocarbons up to C40 was used, while the fluid catalytic cracking (FCC) experiments were carried out in an FCC pilot-plant unit operating in a full circulation mode with continuous catalyst regeneration. Three different catalysts, cofeeding options, and various operating conditions were investigated in the pilot plant. Our results showed that the F−T Wax is very crackable and conversions in the range of 70−90 wt % (on the feed) can be achieved with all catalysts tested....
Industrial & Engineering Chemistry Research, 1996
Industrial & Engineering Chemistry Research, 1988
Oil shale retorting involves heating of solid particles and pyrolysis of the organic matter to pr... more Oil shale retorting involves heating of solid particles and pyrolysis of the organic matter to produce hydrocarbon liquid shale oil. During the pyrolysis process, part of the organic material remains in the inorganic matrix as coke residue. Combustion of the coke residue can provide the energy necessary for retorting. In this paper the use of a fluid bed combustor to burn the coke residue is examined. The basis for predicting the performance of the fluid bed combustor is the application of the two-phase theory of fluidization. The carbon burning efficiency was calculated as a function of temperature, pressure, and bubble size. For the same conditions, the carbonate decomposition and
Industrial & Engineering Chemistry Research, 1998
Industrial & Engineering Chemistry Research, 2005
Fuel, 1998
The combustion kinetics of carbon in carbonaceous deposits, or ‘coke’, on fluid catalytic crackin... more The combustion kinetics of carbon in carbonaceous deposits, or ‘coke’, on fluid catalytic cracking (FCC) zeolite catalysts was studied under differential reactor conditions, in an air stream, at atmospheric pressure, and in a temperature range of 550–710°C. Catalysts with and without Pt were first coked and then subsequently regenerated. Although platinum catalyzes the conversion of CO to CO2, experimental findings
Fuel, 1998
A new procedure is proposed for the effective conversion of biomass flash pyrolysis liquids (BFPL... more A new procedure is proposed for the effective conversion of biomass flash pyrolysis liquids (BFPLs) to transportation fuels. First, the hydrotreatment of a BFPL was studied, both in a thermal and in a catalytic mode. The thermal hydrogenation of BFPLs, a modification of the VEBA Combi Cracking process, is a low cost and low severity hydrogenation process without any operational
Energy & Fuels, 2006
ABSTRACT Hydrogen produced from renewable energy sources is of great interest as an alternative t... more ABSTRACT Hydrogen produced from renewable energy sources is of great interest as an alternative to fossil fuels and as a means for power generation via fuel cells. The aqueous fraction of bio-oil can be effectively reformed to hydrogen-rich streams in the presence of active catalytic materials. In this paper, we present the experimental work carried out in a fixed bed reactor for the reforming of bio-oil. The performance of the reactor was studied at various conditions and compared to the values theoretically predicted by thermodynamic equilibrium. The effect of reaction temperature, steam-to-carbon ratio in the feed, and space velocity was investigated in the presence of a commercial nickel catalyst. Runs were conducted with acetic acid, acetone, and ethylene glycol, representative model compounds of bio-oil, and the aqueous phase of a real bio-oil derived from beech wood. The results of the selected model compounds show that all can be effectively reformed with hydrogen yields up to 90% at reaction temperatures higher than 600 °C and steam-to-carbon ratios higher than 3. The reforming of the aqueous fraction of bio-oil proved to be more difficult, with the hydrogen yield fluctuating at about 60%. The most serious problem encountered in these experiments is coking. The formation of carbonaceous deposits in the upper part of the catalyst zone limits the reforming time and necessitates frequent regeneration of the catalyst.
Catalysis Today, 1998
... Activity measurements were conducted at atmospheric pressure in a conventional flow apparatus... more ... Activity measurements were conducted at atmospheric pressure in a conventional flow apparatus using a quartz fixed bed ... Methane and carbon dioxide at equimolar ratio (1/1) and without any diluent were used as feed with a ... [13]suggested that the beneficial effects of adding ...
Catalysis Today, 2006
Aluminosilicate mesostructures (MSU-SBEA) assembled from zeolite Beta (BEA) seeds exhibited relat... more Aluminosilicate mesostructures (MSU-SBEA) assembled from zeolite Beta (BEA) seeds exhibited relatively high hydrothermal stability and were significantly more active in the cracking of gas–oil compared to MCM-41 after severe steaming pretreatment. The MSU-SBEA mesoporous materials with wormhole framework structure and those having morphology of solid nanoparticles with high interparticle mesoporosity were more steam-stable and more active after severe steaming than
Catalysis Today, 2007
Hydrogen produced from renewable energy sources is of great interest as an alternative to fossil ... more Hydrogen produced from renewable energy sources is of great interest as an alternative to fossil fuels and as a means for clean power generation via fuel cells. The aqueous fraction of bio-oil can be effectively reformed to hydrogen rich streams in the presence of active catalytic materials. In this paper we present the experimental work carried out in a novel
Applied Catalysis B: Environmental, 2004
Applied Catalysis B: Environmental, 2009
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Papers by Iacovos Vasalos