Molecular Physics seminar

Effects of gas-­‐phase alkali species on tar reforming catalyst performance in biomass gasification systems: How to achieve an improved understanding at realistic conditions

by Klas Engvall (Department of Chemical Engineering and Technology, KTH)

FD41 ()


Thermochemical conversion of biomass by means of gasification is an attractive solution to replace fossil with renewable and sustainable fuels. In case of gasification of biomass, tar mitigation is one of the greatest technical challenges to overcome before commercialization. Secondary catalytic tar conversion at a high temperature is a feasible way to solve this problem. Today’s available catalytic conversion technologies generally are limited by sensitivity to alkali salts, inducing deposit formation at the surface. This is resolved by introducing an upstream low temperature filtration step, where alkali salts is separated from the product gas. Due to heat penalties, this is not energy efficient. Therefore, considerable efforts are made to develop a catalytic conversion process positioned directly after the gasifier to even out the process temperature profile. To make things more complicated, alkali is also promoting surface carbon gasification, reducing surface carbon formation. Alkali is, hence, added in small quantities to the catalyst material. One way to tackle these effects is to develop more alkali tolerant catalysts capable of storing or using gas phase alkali in the catalytic conversion process. The development of such a catalyst or catalysts requires a thorough understanding of the effect of gas phase alkali in connection with other species such as sulphur. The issues to be addressed are numerous, including selection of relevant chemical reactions and processes to investigate, methodologies, the pressure gap, catalyst materials, etc. The Seminar will present an overview of on-­‐going research activities at Chemical Technology, KTH and partners in research.