Preface Free

After the publication of a review entitled Carbon Dioxide in Biomass Processing: Contributions to the Green Biorefinery Concept published in Chemical Reviews¹  and the book Ionic Liquids in the Biorefinery Concept,²  there was a need for a book that would reveal the details about the involvement of high-pressure technologies used in biomass processing. One of the first hurdles in this challenge was how to differentiate this book from dozens of other reviews, handbooks and university scripts dealing with the subject of high-pressure extraction of value-added compounds from biological matrixes. The book should not be another work about extraction. That is why this book is not about extraction, at least not about the extraction of volatiles from biomass matrix. The second hurdle was to establish frontiers in terms of the high-pressure processes considered in this book. One may suggest that steam explosion is a high-pressure technology, for example. Also, supercritical water processes of biomass gasification are also high-pressure technologies. Again, this book aims to avoid the description of these technologies as they are an industrial reality, also often obsolete technologies and are broadly presented in numerous books.

Hence there is a question: what does this book offer? This book aims to show the different aspects of high-pressure fluids in biomass processing. It starts with a general introduction to high-pressure technologies with special attention given to processes with water, as it is a fluid always present in biomass. Next, an introduction to the essential properties of high-pressure CO₂ and mixture with water and the benefits from the use of high-pressure fluids in biomass conversion are given. The third chapter tackles one of the most important aspect of biomass processing i.e. biomass pre-treatment. The role of high-pressure water and CO₂–H₂O mixture technologies is presented. This chapter is followed by one that describes a potential use of high-pressure fluids in enzymatic hydrolysis. Next, a series of chapters about the valorization of biomass fractions and the products of hydrolysis of these fractions are presented. The book finishes with perspectives about the development of high-pressure technologies in biomass processing.

The construction of this book allows the reader to dive in the subject of biomass processing with high-pressure fluids starting at a general level and moving on to a more specific and deeper analysis of each of the aspects of biomass processing from a high-pressure fluid perspective.

Additionally, due to the high-quality specialists authoring the chapters in this book, two relevant features have been integrated: (1) engineering aspects of high-pressure technologies and (2) a unique knowledge about complex biomass chemistry.

It is my pleasure to thank all the authors for their commitment and their highly valuable and professional contribution. I also wish to thank Fundação para a Ciência e a Tecnologia (Portugal) for their financial support.

Rafał M. Łukasik

National Laboratory of Energy and

Geology, Lisbon, Portugal