pump failures and plugging of solids at the front end of the catalytic bed the plugging appeared to be primarily organic solids produced from partially pyrolyzed biomass these short lived tests verified the high activity 95 4 cod reduction 2 67 lhsv of the ruthenium stabilized nickel catalyst for biomass gasification with the use of a stirred tank preheater the initial pyrolysis of biomass solids was achieved and effective gasification could be demonstrated at the bench scale and in a scaled up engineering demonstration unit in a scaled up reactor the use of either a stirred tank preheater or a tube in tube heat exchanger was sufficient to liquefy the biomass solids prior to entering the catalyst bed however mineral precipitates from the biomass remained as a significant problem leading to plugging at the front end of the catalyst bed deposits composed of magnesium phosphorus and calcium were observed an additional catalyst deactivation problem was also clearly identified by x ray photometric spectrometry analysis showing sulfur highly associated with the metal in the catalyst the results of the tests described above indicate that organic solids which are a source of plugging in the catalyst bed can be liquefied and or eliminated by heating the feedstock unexpectedly heating of the feedstock can also concurrently cause precipitation of inorganic material that might otherwise deactivate the catalyst by plugging and or poisoning the problem.