Ben Gurion University:
Prof. Ezra Bar-Ziv (Head), Prof.Moti Herskowitz
This group is working on generating the non-catalytic conversion of low-grade biomass of any type into a mixture of H2 and CO2 that will serve as a feedstock for liquid fuel production by a catalytic process.
Gasification is conventionally perceived as converting carbonaceous materials into syngas (H2-CO mixture), which is used to produce liquid fuel through the Fischer-Tropsch (FT) process. However, a recent study has found that the FT processes are inefficient (they require too much work in the gasifier and the FT reactor) and suggests that using H2-CO2 mixtures instead of syngas for liquid fuel production requires much less work, making the liquid fuel production more efficient.
Gasification is a two-stage process comprising:
(1) Pyrolysis of the feedstock into pyrolysis gas and char and
(2) Conversion of the latter into a gaseous mixture.
Both stages are endothermic, requiring the heat obtained from partial oxidation of the feedstock. Oxy-gasification is superior to air-driven gasification in that the efficiency is higher; the gas-phase equilibrium occurs instantly due to high temperatures and long residence times in the reactor; and the mixture produced does not contain nitrogen; but its disadvantage is in the necessity to separate oxygen from air. However, recent membrane separation methods for air have made this route particularly attractive for small systems such as those anticipated for biomass conversions. Oxygen produced by water splitting systems can be used as a cheap source of oxygen. At present, there is little information on the coupled fluid-dynamic/chemical-kinetic system required for biomass oxy-gasification to produce H2-CO2 mixtures, and this lack of knowledge will be addressed within the framework of the I-CORE.
The goal is biomass oxy-gasification that will non-catalytically convert low-grade biomass into H2-CO2 mixtures, which will serve as the feedstock for liquid fuel production by a catalytic process.
The specific goals are to investigate:
(1) The kinetics of pyrolysis of various types of biomass and biomass residues after extraction of oils or sugars
(2) The kinetics of oxy-combustion of the biomass
(3) The conversion pyrolysis gas with steam to CO2-H2 mixtures
(1) A kinetic model of the oxy-gasification of biomass into CO2-H2 mixtures
(2) A technology based on a pulverized-fuel, entrained-flow approach for the production of CO2-H2 mixtures
(3) Criteria for up-scaling the technique by a factor of 100, from the present 50–100 kW gasifier, to commercial size.