Catalytic fast pyrolysis process with impurity removal

A process for treating biomass containing at least 500 ppm alkali and alkaline earth metal components to reduce alkali and alkaline earth metal content to result in a treated biomass comprising steps:

• 1) sizing the biomass to less than or equal to 20 cm size particles, 2) extracting and washing the sized biomass of step 1) in at least one extraction and washing cycle with an extracting and washing fluid comprising acidified water having a pH less than or equal to 2 sufficiently to reduce the content of the alkali and alkaline earth metals by at least 90%, including a mass ratio of extraction and washing fluid to biomass of at least 3, wherein the mass ratio of cellulose to hemicellulose in the washed biomass compared to that found in the untreated biomass has changed by no more than 10%;
• 3) rinsing the washed biomass of step 2) with rinsing fluid comprising water which comprises less than or equal to 5 ppm K or less than or equal to 20 ppm Ca, or both, 4) drying the biomass of step 3) to reduce the water content to less than or equal to 10%, wherein the temperature of step 2) is maintained at a temperature of no more than 90° C. and wherein the washing fluid is an aqueous solution.