Evaluation of the Impact of Temperature and Type of Catalyst on the Bio-Oil Quality Obtained by Biomass Catalytic Pyrolysis Process

摘要

The pyrolysis of biomass is a thermal process that converts, at high yield, solid biomass into a liquid product known as bio-oil. One alternative for the production of a bio-oil of better quality and with lower oxygen content is the use of catalysts in the pyrolysis reactor, rather than an inert, a process called catalytic pyrolysis. The objective of this study was to investigate the effects on product yields and the qualities of products of two different catalysts, one acidic, a commercial fluid catalytic cracking (FCC) catalyst, and a basic one containing hydrotalcite. Inert material, a type of silica, was used as reference. The tests were conducted in a pilot plant with a circulating fluidized bed reactor, specially adapted to perform the catalytic pyrolysis tests, at temperatures of 450°C and 550°C. The results showed that the increase in the residence time of the pyrolysis vapors had a significant impact on products yields, when compared with the profile found in the literature for fast pyrolysis. The FCC catalyst presented higher deoxygenation rates by dehydration, while the hydrotalcite showed greater capacity for decarboxylation. Thus, the use of either the FCC catalyst or hydrotalcite are not suitable for intermediate pyrolysis reactors, generating a product with high water content and low content of organic compounds in bio-oil and produce more coke. None of the materials tested produced bio-oils with considerable hydrocarbons yields and presented high amounts of phenolic compounds. In general, silica had the best results in terms of yield and quality of bio-oil.