Catalytic fast pyrolysis of biomass: from lab-scale research to industrial applications

In recent years, catalytic fast pyrolysis (CFP) of biomass as a means of producing bio-oil with improved physico-chemical properties, has received a lot of attention. This technique, either by adding catalyst particles to the pyrolysis reactor (in situ) or by ex situ vapour treatment, is meant for removal of the oxygen and cracking of the high molecular weight compounds in the primary pyrolysis vapours. So far, various projects have tried/are trying to push catalytic fast pyrolysis to the pilot scale, or even to the commercial scale, but have met varying levels of success. This work therefore tries to answer various research questions that would improve the future strategies related to this technology. These contain the optimal properties of a catalyst for CFP, the consequences of long-term usage of catalysis, and the presence of biomass originated ash in large scale CFP systems. The objective of this research is to investigate possible beneficial effects on the bio-oil quality, of various catalysts applied inside the pyrolysis reactor or in the vapour-product stream, in relationship with the applied process conditions. The catalysts (in total eight proprietary catalysts) were tested in two dedicated lab-scale reactors (with intakes of 500 g/h and 200 g/h) that allow variation of the catalyst loading and contact times while producing larger samples in continuous operation. The effects of successive catalyst regeneration and the presence of biomass ash in catalytic fast pyrolysis of pine wood were investigated, as well. The results consist of a combined summary of three individual research studies, which were extensively studied in a PhD project: i) Screening metal doped catalysts in situ for continuous catalytic fast pyrolysis of pine wood, ii) Catalytic fast pyrolysis of pine wood: Effect of successive catalyst regeneration, and iii) Effect of biomass ash in catalytic fast pyrolysis of pine wood. Some technical recommendations for an ideal, industrial-scale CFP process and our view regarding the future direction of the topic will be included as well